// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/fs/ext4/inode.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/inode.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  64-bit file support on 64-bit platforms by Jakub Jelinek
 *      (jj@sunsite.ms.mff.cuni.cz)
 *
 *  Assorted race fixes, rewrite of ext4_get_block() by Al Viro, 2000
 */

#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/time.h>
#include <linux/highuid.h>
#include <linux/pagemap.h>
#include <linux/dax.h>
#include <linux/quotaops.h>
#include <linux/string.h>
#include <linux/buffer_head.h>
#include <linux/writeback.h>
#include <linux/pagevec.h>
#include <linux/mpage.h>
#include <linux/rmap.h>
#include <linux/namei.h>
#include <linux/uio.h>
#include <linux/bio.h>
#include <linux/workqueue.h>
#include <linux/kernel.h>
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/bitops.h>
#include <linux/iomap.h>
#include <linux/iversion.h>

#include "ext4_jbd2.h"
#include "xattr.h"
#include "acl.h"
#include "truncate.h"

#include <kunit/static_stub.h>

#include <trace/events/ext4.h>

static void ext4_journalled_zero_new_buffers(handle_t *handle,
                                            struct inode *inode,
                                            struct folio *folio,
                                            unsigned from, unsigned to);

static __u32 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw,
                              struct ext4_inode_info *ei)
{
        __u32 csum;
        __u16 dummy_csum = 0;
        int offset = offsetof(struct ext4_inode, i_checksum_lo);
        unsigned int csum_size = sizeof(dummy_csum);

        csum = ext4_chksum(ei->i_csum_seed, (__u8 *)raw, offset);
        csum = ext4_chksum(csum, (__u8 *)&dummy_csum, csum_size);
        offset += csum_size;
        csum = ext4_chksum(csum, (__u8 *)raw + offset,
                           EXT4_GOOD_OLD_INODE_SIZE - offset);

        if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
                offset = offsetof(struct ext4_inode, i_checksum_hi);
                csum = ext4_chksum(csum, (__u8 *)raw + EXT4_GOOD_OLD_INODE_SIZE,
                                   offset - EXT4_GOOD_OLD_INODE_SIZE);
                if (EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi)) {
                        csum = ext4_chksum(csum, (__u8 *)&dummy_csum,
                                           csum_size);
                        offset += csum_size;
                }
                csum = ext4_chksum(csum, (__u8 *)raw + offset,
                                   EXT4_INODE_SIZE(inode->i_sb) - offset);
        }

        return csum;
}

static int ext4_inode_csum_verify(struct inode *inode, struct ext4_inode *raw,
                                  struct ext4_inode_info *ei)
{
        __u32 provided, calculated;

        if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
            cpu_to_le32(EXT4_OS_LINUX) ||
            !ext4_has_feature_metadata_csum(inode->i_sb))
                return 1;

        provided = le16_to_cpu(raw->i_checksum_lo);
        calculated = ext4_inode_csum(inode, raw, ei);
        if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
            EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
                provided |= ((__u32)le16_to_cpu(raw->i_checksum_hi)) << 16;
        else
                calculated &= 0xFFFF;

        return provided == calculated;
}

void ext4_inode_csum_set(struct inode *inode, struct ext4_inode *raw,
                         struct ext4_inode_info *ei)
{
        __u32 csum;

        if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
            cpu_to_le32(EXT4_OS_LINUX) ||
            !ext4_has_feature_metadata_csum(inode->i_sb))
                return;

        csum = ext4_inode_csum(inode, raw, ei);
        raw->i_checksum_lo = cpu_to_le16(csum & 0xFFFF);
        if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
            EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
                raw->i_checksum_hi = cpu_to_le16(csum >> 16);
}

static inline int ext4_begin_ordered_truncate(struct inode *inode,
                                              loff_t new_size)
{
        struct jbd2_inode *jinode = READ_ONCE(EXT4_I(inode)->jinode);

        trace_ext4_begin_ordered_truncate(inode, new_size);
        /*
         * If jinode is zero, then we never opened the file for
         * writing, so there's no need to call
         * jbd2_journal_begin_ordered_truncate() since there's no
         * outstanding writes we need to flush.
         */
        if (!jinode)
                return 0;
        return jbd2_journal_begin_ordered_truncate(EXT4_JOURNAL(inode),
                                                   jinode,
                                                   new_size);
}

/*
 * Test whether an inode is a fast symlink.
 * A fast symlink has its symlink data stored in ext4_inode_info->i_data.
 */
int ext4_inode_is_fast_symlink(struct inode *inode)
{
        if (!ext4_has_feature_ea_inode(inode->i_sb)) {
                int ea_blocks = EXT4_I(inode)->i_file_acl ?
                                EXT4_CLUSTER_SIZE(inode->i_sb) >> 9 : 0;

                if (ext4_has_inline_data(inode))
                        return 0;

                return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
        }
        return S_ISLNK(inode->i_mode) && inode->i_size &&
               (inode->i_size < EXT4_N_BLOCKS * 4);
}

/*
 * Called at the last iput() if i_nlink is zero.
 */
void ext4_evict_inode(struct inode *inode)
{
        handle_t *handle;
        int err;
        /*
         * Credits for final inode cleanup and freeing:
         * sb + inode (ext4_orphan_del()), block bitmap, group descriptor
         * (xattr block freeing), bitmap, group descriptor (inode freeing)
         */
        int extra_credits = 6;
        struct ext4_xattr_inode_array *ea_inode_array = NULL;
        bool freeze_protected = false;

        trace_ext4_evict_inode(inode);

        dax_break_layout_final(inode);

        if (EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL)
                ext4_evict_ea_inode(inode);
        if (inode->i_nlink) {
                /*
                 * If there's dirty page will lead to data loss, user
                 * could see stale data.
                 */
                if (unlikely(!ext4_emergency_state(inode->i_sb) &&
                    mapping_tagged(&inode->i_data, PAGECACHE_TAG_DIRTY)))
                        ext4_warning_inode(inode, "data will be lost");

                truncate_inode_pages_final(&inode->i_data);

                goto no_delete;
        }

        if (is_bad_inode(inode))
                goto no_delete;
        dquot_initialize(inode);

        if (ext4_should_order_data(inode))
                ext4_begin_ordered_truncate(inode, 0);
        truncate_inode_pages_final(&inode->i_data);

        /*
         * For inodes with journalled data, transaction commit could have
         * dirtied the inode. And for inodes with dioread_nolock, unwritten
         * extents converting worker could merge extents and also have dirtied
         * the inode. Flush worker is ignoring it because of I_FREEING flag but
         * we still need to remove the inode from the writeback lists.
         */
        inode_io_list_del(inode);

        /*
         * Protect us against freezing - iput() caller didn't have to have any
         * protection against it. When we are in a running transaction though,
         * we are already protected against freezing and we cannot grab further
         * protection due to lock ordering constraints.
         */
        if (!ext4_journal_current_handle()) {
                sb_start_intwrite(inode->i_sb);
                freeze_protected = true;
        }

        if (!IS_NOQUOTA(inode))
                extra_credits += EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb);

        /*
         * Block bitmap, group descriptor, and inode are accounted in both
         * ext4_blocks_for_truncate() and extra_credits. So subtract 3.
         */
        handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE,
                         ext4_blocks_for_truncate(inode) + extra_credits - 3);
        if (IS_ERR(handle)) {
                ext4_std_error(inode->i_sb, PTR_ERR(handle));
                /*
                 * If we're going to skip the normal cleanup, we still need to
                 * make sure that the in-core orphan linked list is properly
                 * cleaned up.
                 */
                ext4_orphan_del(NULL, inode);
                if (freeze_protected)
                        sb_end_intwrite(inode->i_sb);
                goto no_delete;
        }

        if (IS_SYNC(inode))
                ext4_handle_sync(handle);

        /*
         * Set inode->i_size to 0 before calling ext4_truncate(). We need
         * special handling of symlinks here because i_size is used to
         * determine whether ext4_inode_info->i_data contains symlink data or
         * block mappings. Setting i_size to 0 will remove its fast symlink
         * status. Erase i_data so that it becomes a valid empty block map.
         */
        if (ext4_inode_is_fast_symlink(inode))
                memset(EXT4_I(inode)->i_data, 0, sizeof(EXT4_I(inode)->i_data));
        inode->i_size = 0;
        err = ext4_mark_inode_dirty(handle, inode);
        if (err) {
                ext4_warning(inode->i_sb,
                             "couldn't mark inode dirty (err %d)", err);
                goto stop_handle;
        }
        if (inode->i_blocks) {
                err = ext4_truncate(inode);
                if (err) {
                        ext4_error_err(inode->i_sb, -err,
                                       "couldn't truncate inode %lu (err %d)",
                                       inode->i_ino, err);
                        goto stop_handle;
                }
        }

        /* Remove xattr references. */
        err = ext4_xattr_delete_inode(handle, inode, &ea_inode_array,
                                      extra_credits);
        if (err) {
                ext4_warning(inode->i_sb, "xattr delete (err %d)", err);
stop_handle:
                ext4_journal_stop(handle);
                ext4_orphan_del(NULL, inode);
                if (freeze_protected)
                        sb_end_intwrite(inode->i_sb);
                ext4_xattr_inode_array_free(ea_inode_array);
                goto no_delete;
        }

        /*
         * Kill off the orphan record which ext4_truncate created.
         * AKPM: I think this can be inside the above `if'.
         * Note that ext4_orphan_del() has to be able to cope with the
         * deletion of a non-existent orphan - this is because we don't
         * know if ext4_truncate() actually created an orphan record.
         * (Well, we could do this if we need to, but heck - it works)
         */
        ext4_orphan_del(handle, inode);
        EXT4_I(inode)->i_dtime  = (__u32)ktime_get_real_seconds();

        /*
         * One subtle ordering requirement: if anything has gone wrong
         * (transaction abort, IO errors, whatever), then we can still
         * do these next steps (the fs will already have been marked as
         * having errors), but we can't free the inode if the mark_dirty
         * fails.
         */
        if (ext4_mark_inode_dirty(handle, inode))
                /* If that failed, just do the required in-core inode clear. */
                ext4_clear_inode(inode);
        else
                ext4_free_inode(handle, inode);
        ext4_journal_stop(handle);
        if (freeze_protected)
                sb_end_intwrite(inode->i_sb);
        ext4_xattr_inode_array_free(ea_inode_array);
        return;
no_delete:
        /*
         * Check out some where else accidentally dirty the evicting inode,
         * which may probably cause inode use-after-free issues later.
         */
        WARN_ON_ONCE(!list_empty_careful(&inode->i_io_list));

        if (!list_empty(&EXT4_I(inode)->i_fc_list))
                ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_NOMEM, NULL);
        ext4_clear_inode(inode);        /* We must guarantee clearing of inode... */
}

#ifdef CONFIG_QUOTA
qsize_t *ext4_get_reserved_space(struct inode *inode)
{
        return &EXT4_I(inode)->i_reserved_quota;
}
#endif

/*
 * Called with i_data_sem down, which is important since we can call
 * ext4_discard_preallocations() from here.
 */
void ext4_da_update_reserve_space(struct inode *inode,
                                        int used, int quota_claim)
{
        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
        struct ext4_inode_info *ei = EXT4_I(inode);

        spin_lock(&ei->i_block_reservation_lock);
        trace_ext4_da_update_reserve_space(inode, used, quota_claim);
        if (unlikely(used > ei->i_reserved_data_blocks)) {
                ext4_warning(inode->i_sb, "%s: ino %lu, used %d "
                         "with only %d reserved data blocks",
                         __func__, inode->i_ino, used,
                         ei->i_reserved_data_blocks);
                WARN_ON(1);
                used = ei->i_reserved_data_blocks;
        }

        /* Update per-inode reservations */
        ei->i_reserved_data_blocks -= used;
        percpu_counter_sub(&sbi->s_dirtyclusters_counter, used);

        spin_unlock(&ei->i_block_reservation_lock);

        /* Update quota subsystem for data blocks */
        if (quota_claim)
                dquot_claim_block(inode, EXT4_C2B(sbi, used));
        else {
                /*
                 * We did fallocate with an offset that is already delayed
                 * allocated. So on delayed allocated writeback we should
                 * not re-claim the quota for fallocated blocks.
                 */
                dquot_release_reservation_block(inode, EXT4_C2B(sbi, used));
        }

        /*
         * If we have done all the pending block allocations and if
         * there aren't any writers on the inode, we can discard the
         * inode's preallocations.
         */
        if ((ei->i_reserved_data_blocks == 0) &&
            !inode_is_open_for_write(inode))
                ext4_discard_preallocations(inode);
}

static int __check_block_validity(struct inode *inode, const char *func,
                                unsigned int line,
                                struct ext4_map_blocks *map)
{
        journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;

        if (journal && inode == journal->j_inode)
                return 0;

        if (!ext4_inode_block_valid(inode, map->m_pblk, map->m_len)) {
                ext4_error_inode(inode, func, line, map->m_pblk,
                                 "lblock %lu mapped to illegal pblock %llu "
                                 "(length %d)", (unsigned long) map->m_lblk,
                                 map->m_pblk, map->m_len);
                return -EFSCORRUPTED;
        }
        return 0;
}

int ext4_issue_zeroout(struct inode *inode, ext4_lblk_t lblk, ext4_fsblk_t pblk,
                       ext4_lblk_t len)
{
        int ret;

        KUNIT_STATIC_STUB_REDIRECT(ext4_issue_zeroout, inode, lblk, pblk, len);

        if (IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode))
                return fscrypt_zeroout_range(inode, lblk, pblk, len);

        ret = sb_issue_zeroout(inode->i_sb, pblk, len, GFP_NOFS);
        if (ret > 0)
                ret = 0;

        return ret;
}

/*
 * For generic regular files, when updating the extent tree, Ext4 should
 * hold the i_rwsem and invalidate_lock exclusively. This ensures
 * exclusion against concurrent page faults, as well as reads and writes.
 */
#ifdef CONFIG_EXT4_DEBUG
void ext4_check_map_extents_env(struct inode *inode)
{
        if (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
                return;

        if (!S_ISREG(inode->i_mode) ||
            IS_NOQUOTA(inode) || IS_VERITY(inode) ||
            is_special_ino(inode->i_sb, inode->i_ino) ||
            (inode_state_read_once(inode) & (I_FREEING | I_WILL_FREE | I_NEW)) ||
            ext4_test_inode_flag(inode, EXT4_INODE_EA_INODE) ||
            ext4_verity_in_progress(inode))
                return;

        WARN_ON_ONCE(!inode_is_locked(inode) &&
                     !rwsem_is_locked(&inode->i_mapping->invalidate_lock));
}
#else
void ext4_check_map_extents_env(struct inode *inode) {}
#endif

#define check_block_validity(inode, map)        \
        __check_block_validity((inode), __func__, __LINE__, (map))

#ifdef ES_AGGRESSIVE_TEST
static void ext4_map_blocks_es_recheck(handle_t *handle,
                                       struct inode *inode,
                                       struct ext4_map_blocks *es_map,
                                       struct ext4_map_blocks *map,
                                       int flags)
{
        int retval;

        map->m_flags = 0;
        /*
         * There is a race window that the result is not the same.
         * e.g. xfstests #223 when dioread_nolock enables.  The reason
         * is that we lookup a block mapping in extent status tree with
         * out taking i_data_sem.  So at the time the unwritten extent
         * could be converted.
         */
        down_read(&EXT4_I(inode)->i_data_sem);
        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
                retval = ext4_ext_map_blocks(handle, inode, map, 0);
        } else {
                retval = ext4_ind_map_blocks(handle, inode, map, 0);
        }
        up_read((&EXT4_I(inode)->i_data_sem));

        /*
         * We don't check m_len because extent will be collpased in status
         * tree.  So the m_len might not equal.
         */
        if (es_map->m_lblk != map->m_lblk ||
            es_map->m_flags != map->m_flags ||
            es_map->m_pblk != map->m_pblk) {
                printk("ES cache assertion failed for inode: %lu "
                       "es_cached ex [%d/%d/%llu/%x] != "
                       "found ex [%d/%d/%llu/%x] retval %d flags %x\n",
                       inode->i_ino, es_map->m_lblk, es_map->m_len,
                       es_map->m_pblk, es_map->m_flags, map->m_lblk,
                       map->m_len, map->m_pblk, map->m_flags,
                       retval, flags);
        }
}
#endif /* ES_AGGRESSIVE_TEST */

static int ext4_map_query_blocks_next_in_leaf(handle_t *handle,
                        struct inode *inode, struct ext4_map_blocks *map,
                        unsigned int orig_mlen)
{
        struct ext4_map_blocks map2;
        unsigned int status, status2;
        int retval;

        status = map->m_flags & EXT4_MAP_UNWRITTEN ?
                EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;

        WARN_ON_ONCE(!(map->m_flags & EXT4_MAP_QUERY_LAST_IN_LEAF));
        WARN_ON_ONCE(orig_mlen <= map->m_len);

        /* Prepare map2 for lookup in next leaf block */
        map2.m_lblk = map->m_lblk + map->m_len;
        map2.m_len = orig_mlen - map->m_len;
        map2.m_flags = 0;
        retval = ext4_ext_map_blocks(handle, inode, &map2, 0);

        if (retval <= 0) {
                ext4_es_cache_extent(inode, map->m_lblk, map->m_len,
                                     map->m_pblk, status);
                return map->m_len;
        }

        if (unlikely(retval != map2.m_len)) {
                ext4_warning(inode->i_sb,
                             "ES len assertion failed for inode "
                             "%lu: retval %d != map->m_len %d",
                             inode->i_ino, retval, map2.m_len);
                WARN_ON(1);
        }

        status2 = map2.m_flags & EXT4_MAP_UNWRITTEN ?
                EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;

        /*
         * If map2 is contiguous with map, then let's insert it as a single
         * extent in es cache and return the combined length of both the maps.
         */
        if (map->m_pblk + map->m_len == map2.m_pblk &&
                        status == status2) {
                ext4_es_cache_extent(inode, map->m_lblk,
                                     map->m_len + map2.m_len, map->m_pblk,
                                     status);
                map->m_len += map2.m_len;
        } else {
                ext4_es_cache_extent(inode, map->m_lblk, map->m_len,
                                     map->m_pblk, status);
        }

        return map->m_len;
}

int ext4_map_query_blocks(handle_t *handle, struct inode *inode,
                          struct ext4_map_blocks *map, int flags)
{
        unsigned int status;
        int retval;
        unsigned int orig_mlen = map->m_len;

        flags &= EXT4_EX_QUERY_FILTER;
        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
                retval = ext4_ext_map_blocks(handle, inode, map, flags);
        else
                retval = ext4_ind_map_blocks(handle, inode, map, flags);
        if (retval < 0)
                return retval;

        /* A hole? */
        if (retval == 0)
                goto out;

        if (unlikely(retval != map->m_len)) {
                ext4_warning(inode->i_sb,
                             "ES len assertion failed for inode "
                             "%lu: retval %d != map->m_len %d",
                             inode->i_ino, retval, map->m_len);
                WARN_ON(1);
        }

        /*
         * No need to query next in leaf:
         * - if returned extent is not last in leaf or
         * - if the last in leaf is the full requested range
         */
        if (!(map->m_flags & EXT4_MAP_QUERY_LAST_IN_LEAF) ||
                        map->m_len == orig_mlen) {
                status = map->m_flags & EXT4_MAP_UNWRITTEN ?
                                EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
                ext4_es_cache_extent(inode, map->m_lblk, map->m_len,
                                     map->m_pblk, status);
        } else {
                retval = ext4_map_query_blocks_next_in_leaf(handle, inode, map,
                                                            orig_mlen);
        }
out:
        map->m_seq = READ_ONCE(EXT4_I(inode)->i_es_seq);
        return retval;
}

int ext4_map_create_blocks(handle_t *handle, struct inode *inode,
                           struct ext4_map_blocks *map, int flags)
{
        unsigned int status;
        int err, retval = 0;

        /*
         * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE
         * indicates that the blocks and quotas has already been
         * checked when the data was copied into the page cache.
         */
        if (map->m_flags & EXT4_MAP_DELAYED)
                flags |= EXT4_GET_BLOCKS_DELALLOC_RESERVE;

        /*
         * Here we clear m_flags because after allocating an new extent,
         * it will be set again.
         */
        map->m_flags &= ~EXT4_MAP_FLAGS;

        /*
         * We need to check for EXT4 here because migrate could have
         * changed the inode type in between.
         */
        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
                retval = ext4_ext_map_blocks(handle, inode, map, flags);
        } else {
                retval = ext4_ind_map_blocks(handle, inode, map, flags);

                /*
                 * We allocated new blocks which will result in i_data's
                 * format changing. Force the migrate to fail by clearing
                 * migrate flags.
                 */
                if (retval > 0 && map->m_flags & EXT4_MAP_NEW)
                        ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
        }
        if (retval <= 0)
                return retval;

        if (unlikely(retval != map->m_len)) {
                ext4_warning(inode->i_sb,
                             "ES len assertion failed for inode %lu: "
                             "retval %d != map->m_len %d",
                             inode->i_ino, retval, map->m_len);
                WARN_ON(1);
        }

        /*
         * We have to zeroout blocks before inserting them into extent
         * status tree. Otherwise someone could look them up there and
         * use them before they are really zeroed. We also have to
         * unmap metadata before zeroing as otherwise writeback can
         * overwrite zeros with stale data from block device.
         */
        if (flags & EXT4_GET_BLOCKS_ZERO &&
            map->m_flags & EXT4_MAP_MAPPED && map->m_flags & EXT4_MAP_NEW) {
                err = ext4_issue_zeroout(inode, map->m_lblk, map->m_pblk,
                                         map->m_len);
                if (err)
                        return err;
        }

        status = map->m_flags & EXT4_MAP_UNWRITTEN ?
                        EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
        ext4_es_insert_extent(inode, map->m_lblk, map->m_len, map->m_pblk,
                              status, flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE);
        map->m_seq = READ_ONCE(EXT4_I(inode)->i_es_seq);

        return retval;
}

/*
 * The ext4_map_blocks() function tries to look up the requested blocks,
 * and returns if the blocks are already mapped.
 *
 * Otherwise it takes the write lock of the i_data_sem and allocate blocks
 * and store the allocated blocks in the result buffer head and mark it
 * mapped.
 *
 * If file type is extents based, it will call ext4_ext_map_blocks(),
 * Otherwise, call with ext4_ind_map_blocks() to handle indirect mapping
 * based files
 *
 * On success, it returns the number of blocks being mapped or allocated.
 * If flags doesn't contain EXT4_GET_BLOCKS_CREATE the blocks are
 * pre-allocated and unwritten, the resulting @map is marked as unwritten.
 * If the flags contain EXT4_GET_BLOCKS_CREATE, it will mark @map as mapped.
 *
 * It returns 0 if plain look up failed (blocks have not been allocated), in
 * that case, @map is returned as unmapped but we still do fill map->m_len to
 * indicate the length of a hole starting at map->m_lblk.
 *
 * It returns the error in case of allocation failure.
 */
int ext4_map_blocks(handle_t *handle, struct inode *inode,
                    struct ext4_map_blocks *map, int flags)
{
        struct extent_status es;
        int retval;
        int ret = 0;
        unsigned int orig_mlen = map->m_len;
#ifdef ES_AGGRESSIVE_TEST
        struct ext4_map_blocks orig_map;

        memcpy(&orig_map, map, sizeof(*map));
#endif

        map->m_flags = 0;
        ext_debug(inode, "flag 0x%x, max_blocks %u, logical block %lu\n",
                  flags, map->m_len, (unsigned long) map->m_lblk);

        /*
         * ext4_map_blocks returns an int, and m_len is an unsigned int
         */
        if (unlikely(map->m_len > INT_MAX))
                map->m_len = INT_MAX;

        /* We can handle the block number less than EXT_MAX_BLOCKS */
        if (unlikely(map->m_lblk >= EXT_MAX_BLOCKS))
                return -EFSCORRUPTED;

        /*
         * Callers from the context of data submission are the only exceptions
         * for regular files that do not hold the i_rwsem or invalidate_lock.
         * However, caching unrelated ranges is not permitted.
         */
        if (flags & EXT4_GET_BLOCKS_IO_SUBMIT)
                WARN_ON_ONCE(!(flags & EXT4_EX_NOCACHE));
        else
                ext4_check_map_extents_env(inode);

        /* Lookup extent status tree firstly */
        if (ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es, &map->m_seq)) {
                if (ext4_es_is_written(&es) || ext4_es_is_unwritten(&es)) {
                        map->m_pblk = ext4_es_pblock(&es) +
                                        map->m_lblk - es.es_lblk;
                        map->m_flags |= ext4_es_is_written(&es) ?
                                        EXT4_MAP_MAPPED : EXT4_MAP_UNWRITTEN;
                        retval = es.es_len - (map->m_lblk - es.es_lblk);
                        if (retval > map->m_len)
                                retval = map->m_len;
                        map->m_len = retval;
                } else if (ext4_es_is_delayed(&es) || ext4_es_is_hole(&es)) {
                        map->m_pblk = 0;
                        map->m_flags |= ext4_es_is_delayed(&es) ?
                                        EXT4_MAP_DELAYED : 0;
                        retval = es.es_len - (map->m_lblk - es.es_lblk);
                        if (retval > map->m_len)
                                retval = map->m_len;
                        map->m_len = retval;
                        retval = 0;
                } else {
                        BUG();
                }

                if (flags & EXT4_GET_BLOCKS_CACHED_NOWAIT)
                        return retval;
#ifdef ES_AGGRESSIVE_TEST
                ext4_map_blocks_es_recheck(handle, inode, map,
                                           &orig_map, flags);
#endif
                if (!(flags & EXT4_GET_BLOCKS_QUERY_LAST_IN_LEAF) ||
                                orig_mlen == map->m_len)
                        goto found;

                map->m_len = orig_mlen;
        }
        /*
         * In the query cache no-wait mode, nothing we can do more if we
         * cannot find extent in the cache.
         */
        if (flags & EXT4_GET_BLOCKS_CACHED_NOWAIT)
                return 0;

        /*
         * Try to see if we can get the block without requesting a new
         * file system block.
         */
        down_read(&EXT4_I(inode)->i_data_sem);
        retval = ext4_map_query_blocks(handle, inode, map, flags);
        up_read((&EXT4_I(inode)->i_data_sem));

found:
        if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
                ret = check_block_validity(inode, map);
                if (ret != 0)
                        return ret;
        }

        /* If it is only a block(s) look up */
        if ((flags & EXT4_GET_BLOCKS_CREATE) == 0)
                return retval;

        /*
         * Returns if the blocks have already allocated
         *
         * Note that if blocks have been preallocated
         * ext4_ext_map_blocks() returns with buffer head unmapped
         */
        if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED)
                /*
                 * If we need to convert extent to unwritten
                 * we continue and do the actual work in
                 * ext4_ext_map_blocks()
                 */
                if (!(flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN))
                        return retval;


        ext4_fc_track_inode(handle, inode);
        /*
         * New blocks allocate and/or writing to unwritten extent
         * will possibly result in updating i_data, so we take
         * the write lock of i_data_sem, and call get_block()
         * with create == 1 flag.
         */
        down_write(&EXT4_I(inode)->i_data_sem);
        retval = ext4_map_create_blocks(handle, inode, map, flags);
        up_write((&EXT4_I(inode)->i_data_sem));

        if (retval < 0)
                ext_debug(inode, "failed with err %d\n", retval);
        if (retval <= 0)
                return retval;

        if (map->m_flags & EXT4_MAP_MAPPED) {
                ret = check_block_validity(inode, map);
                if (ret != 0)
                        return ret;

                /*
                 * Inodes with freshly allocated blocks where contents will be
                 * visible after transaction commit must be on transaction's
                 * ordered data list.
                 */
                if (map->m_flags & EXT4_MAP_NEW &&
                    !(map->m_flags & EXT4_MAP_UNWRITTEN) &&
                    !(flags & EXT4_GET_BLOCKS_ZERO) &&
                    !ext4_is_quota_file(inode) &&
                    ext4_should_order_data(inode)) {
                        loff_t start_byte = EXT4_LBLK_TO_B(inode, map->m_lblk);
                        loff_t length = EXT4_LBLK_TO_B(inode, map->m_len);

                        if (flags & EXT4_GET_BLOCKS_IO_SUBMIT)
                                ret = ext4_jbd2_inode_add_wait(handle, inode,
                                                start_byte, length);
                        else
                                ret = ext4_jbd2_inode_add_write(handle, inode,
                                                start_byte, length);
                        if (ret)
                                return ret;
                }
        }
        ext4_fc_track_range(handle, inode, map->m_lblk, map->m_lblk +
                            map->m_len - 1);
        return retval;
}

/*
 * Update EXT4_MAP_FLAGS in bh->b_state. For buffer heads attached to pages
 * we have to be careful as someone else may be manipulating b_state as well.
 */
static void ext4_update_bh_state(struct buffer_head *bh, unsigned long flags)
{
        unsigned long old_state;
        unsigned long new_state;

        flags &= EXT4_MAP_FLAGS;

        /* Dummy buffer_head? Set non-atomically. */
        if (!bh->b_folio) {
                bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | flags;
                return;
        }
        /*
         * Someone else may be modifying b_state. Be careful! This is ugly but
         * once we get rid of using bh as a container for mapping information
         * to pass to / from get_block functions, this can go away.
         */
        old_state = READ_ONCE(bh->b_state);
        do {
                new_state = (old_state & ~EXT4_MAP_FLAGS) | flags;
        } while (unlikely(!try_cmpxchg(&bh->b_state, &old_state, new_state)));
}

/*
 * Make sure that the current journal transaction has enough credits to map
 * one extent. Return -EAGAIN if it cannot extend the current running
 * transaction.
 */
static inline int ext4_journal_ensure_extent_credits(handle_t *handle,
                                                     struct inode *inode)
{
        int credits;
        int ret;

        /* Called from ext4_da_write_begin() which has no handle started? */
        if (!handle)
                return 0;

        credits = ext4_chunk_trans_blocks(inode, 1);
        ret = __ext4_journal_ensure_credits(handle, credits, credits, 0);
        return ret <= 0 ? ret : -EAGAIN;
}

static int _ext4_get_block(struct inode *inode, sector_t iblock,
                           struct buffer_head *bh, int flags)
{
        struct ext4_map_blocks map;
        int ret = 0;

        if (ext4_has_inline_data(inode))
                return -ERANGE;

        map.m_lblk = iblock;
        map.m_len = bh->b_size >> inode->i_blkbits;

        ret = ext4_map_blocks(ext4_journal_current_handle(), inode, &map,
                              flags);
        if (ret > 0) {
                map_bh(bh, inode->i_sb, map.m_pblk);
                ext4_update_bh_state(bh, map.m_flags);
                bh->b_size = inode->i_sb->s_blocksize * map.m_len;
                ret = 0;
        } else if (ret == 0) {
                /* hole case, need to fill in bh->b_size */
                bh->b_size = inode->i_sb->s_blocksize * map.m_len;
        }
        return ret;
}

int ext4_get_block(struct inode *inode, sector_t iblock,
                   struct buffer_head *bh, int create)
{
        return _ext4_get_block(inode, iblock, bh,
                               create ? EXT4_GET_BLOCKS_CREATE : 0);
}

/*
 * Get block function used when preparing for buffered write if we require
 * creating an unwritten extent if blocks haven't been allocated.  The extent
 * will be converted to written after the IO is complete.
 */
int ext4_get_block_unwritten(struct inode *inode, sector_t iblock,
                             struct buffer_head *bh_result, int create)
{
        int ret = 0;

        ext4_debug("ext4_get_block_unwritten: inode %lu, create flag %d\n",
                   inode->i_ino, create);
        ret = _ext4_get_block(inode, iblock, bh_result,
                               EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT);

        /*
         * If the buffer is marked unwritten, mark it as new to make sure it is
         * zeroed out correctly in case of partial writes. Otherwise, there is
         * a chance of stale data getting exposed.
         */
        if (ret == 0 && buffer_unwritten(bh_result))
                set_buffer_new(bh_result);

        return ret;
}

/* Maximum number of blocks we map for direct IO at once. */
#define DIO_MAX_BLOCKS 4096

/*
 * `handle' can be NULL if create is zero
 */
struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
                                ext4_lblk_t block, int map_flags)
{
        struct ext4_map_blocks map;
        struct buffer_head *bh;
        int create = map_flags & EXT4_GET_BLOCKS_CREATE;
        bool nowait = map_flags & EXT4_GET_BLOCKS_CACHED_NOWAIT;
        int err;

        ASSERT((EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
                    || handle != NULL || create == 0);
        ASSERT(create == 0 || !nowait);

        map.m_lblk = block;
        map.m_len = 1;
        err = ext4_map_blocks(handle, inode, &map, map_flags);

        if (err == 0)
                return create ? ERR_PTR(-ENOSPC) : NULL;
        if (err < 0)
                return ERR_PTR(err);

        if (nowait)
                return sb_find_get_block(inode->i_sb, map.m_pblk);

        /*
         * Since bh could introduce extra ref count such as referred by
         * journal_head etc. Try to avoid using __GFP_MOVABLE here
         * as it may fail the migration when journal_head remains.
         */
        bh = getblk_unmovable(inode->i_sb->s_bdev, map.m_pblk,
                                inode->i_sb->s_blocksize);

        if (unlikely(!bh))
                return ERR_PTR(-ENOMEM);
        if (map.m_flags & EXT4_MAP_NEW) {
                ASSERT(create != 0);
                ASSERT((EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
                            || (handle != NULL));

                /*
                 * Now that we do not always journal data, we should
                 * keep in mind whether this should always journal the
                 * new buffer as metadata.  For now, regular file
                 * writes use ext4_get_block instead, so it's not a
                 * problem.
                 */
                lock_buffer(bh);
                BUFFER_TRACE(bh, "call get_create_access");
                err = ext4_journal_get_create_access(handle, inode->i_sb, bh,
                                                     EXT4_JTR_NONE);
                if (unlikely(err)) {
                        unlock_buffer(bh);
                        goto errout;
                }
                if (!buffer_uptodate(bh)) {
                        memset(bh->b_data, 0, inode->i_sb->s_blocksize);
                        set_buffer_uptodate(bh);
                }
                unlock_buffer(bh);
                BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
                err = ext4_handle_dirty_metadata(handle, inode, bh);
                if (unlikely(err))
                        goto errout;
        } else
                BUFFER_TRACE(bh, "not a new buffer");
        return bh;
errout:
        brelse(bh);
        return ERR_PTR(err);
}

struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
                               ext4_lblk_t block, int map_flags)
{
        struct buffer_head *bh;
        int ret;

        bh = ext4_getblk(handle, inode, block, map_flags);
        if (IS_ERR(bh))
                return bh;
        if (!bh || ext4_buffer_uptodate(bh))
                return bh;

        ret = ext4_read_bh_lock(bh, REQ_META | REQ_PRIO, true);
        if (ret) {
                put_bh(bh);
                return ERR_PTR(ret);
        }
        return bh;
}

/* Read a contiguous batch of blocks. */
int ext4_bread_batch(struct inode *inode, ext4_lblk_t block, int bh_count,
                     bool wait, struct buffer_head **bhs)
{
        int i, err;

        for (i = 0; i < bh_count; i++) {
                bhs[i] = ext4_getblk(NULL, inode, block + i, 0 /* map_flags */);
                if (IS_ERR(bhs[i])) {
                        err = PTR_ERR(bhs[i]);
                        bh_count = i;
                        goto out_brelse;
                }
        }

        for (i = 0; i < bh_count; i++)
                /* Note that NULL bhs[i] is valid because of holes. */
                if (bhs[i] && !ext4_buffer_uptodate(bhs[i]))
                        ext4_read_bh_lock(bhs[i], REQ_META | REQ_PRIO, false);

        if (!wait)
                return 0;

        for (i = 0; i < bh_count; i++)
                if (bhs[i])
                        wait_on_buffer(bhs[i]);

        for (i = 0; i < bh_count; i++) {
                if (bhs[i] && !buffer_uptodate(bhs[i])) {
                        err = -EIO;
                        goto out_brelse;
                }
        }
        return 0;

out_brelse:
        for (i = 0; i < bh_count; i++) {
                brelse(bhs[i]);
                bhs[i] = NULL;
        }
        return err;
}

int ext4_walk_page_buffers(handle_t *handle, struct inode *inode,
                           struct buffer_head *head,
                           unsigned from,
                           unsigned to,
                           int *partial,
                           int (*fn)(handle_t *handle, struct inode *inode,
                                     struct buffer_head *bh))
{
        struct buffer_head *bh;
        unsigned block_start, block_end;
        unsigned blocksize = head->b_size;
        int err, ret = 0;
        struct buffer_head *next;

        for (bh = head, block_start = 0;
             ret == 0 && (bh != head || !block_start);
             block_start = block_end, bh = next) {
                next = bh->b_this_page;
                block_end = block_start + blocksize;
                if (block_end <= from || block_start >= to) {
                        if (partial && !buffer_uptodate(bh))
                                *partial = 1;
                        continue;
                }
                err = (*fn)(handle, inode, bh);
                if (!ret)
                        ret = err;
        }
        return ret;
}

/*
 * Helper for handling dirtying of journalled data. We also mark the folio as
 * dirty so that writeback code knows about this page (and inode) contains
 * dirty data. ext4_writepages() then commits appropriate transaction to
 * make data stable.
 */
static int ext4_dirty_journalled_data(handle_t *handle, struct buffer_head *bh)
{
        struct folio *folio = bh->b_folio;
        struct inode *inode = folio->mapping->host;

        /* only regular files have a_ops */
        if (S_ISREG(inode->i_mode))
                folio_mark_dirty(folio);
        return ext4_handle_dirty_metadata(handle, NULL, bh);
}

int do_journal_get_write_access(handle_t *handle, struct inode *inode,
                                struct buffer_head *bh)
{
        if (!buffer_mapped(bh) || buffer_freed(bh))
                return 0;
        BUFFER_TRACE(bh, "get write access");
        return ext4_journal_get_write_access(handle, inode->i_sb, bh,
                                            EXT4_JTR_NONE);
}

int ext4_block_write_begin(handle_t *handle, struct folio *folio,
                           loff_t pos, unsigned len,
                           get_block_t *get_block)
{
        unsigned int from = offset_in_folio(folio, pos);
        unsigned to = from + len;
        struct inode *inode = folio->mapping->host;
        unsigned block_start, block_end;
        sector_t block;
        int err = 0;
        unsigned int blocksize = i_blocksize(inode);
        struct buffer_head *bh, *head, *wait[2];
        int nr_wait = 0;
        int i;
        bool should_journal_data = ext4_should_journal_data(inode);

        BUG_ON(!folio_test_locked(folio));
        BUG_ON(to > folio_size(folio));
        BUG_ON(from > to);
        WARN_ON_ONCE(blocksize > folio_size(folio));

        head = folio_buffers(folio);
        if (!head)
                head = create_empty_buffers(folio, blocksize, 0);
        block = EXT4_PG_TO_LBLK(inode, folio->index);

        for (bh = head, block_start = 0; bh != head || !block_start;
            block++, block_start = block_end, bh = bh->b_this_page) {
                block_end = block_start + blocksize;
                if (block_end <= from || block_start >= to) {
                        if (folio_test_uptodate(folio)) {
                                set_buffer_uptodate(bh);
                        }
                        continue;
                }
                if (WARN_ON_ONCE(buffer_new(bh)))
                        clear_buffer_new(bh);
                if (!buffer_mapped(bh)) {
                        WARN_ON(bh->b_size != blocksize);
                        err = ext4_journal_ensure_extent_credits(handle, inode);
                        if (!err)
                                err = get_block(inode, block, bh, 1);
                        if (err)
                                break;
                        if (buffer_new(bh)) {
                                /*
                                 * We may be zeroing partial buffers or all new
                                 * buffers in case of failure. Prepare JBD2 for
                                 * that.
                                 */
                                if (should_journal_data)
                                        do_journal_get_write_access(handle,
                                                                    inode, bh);
                                if (folio_test_uptodate(folio)) {
                                        /*
                                         * Unlike __block_write_begin() we leave
                                         * dirtying of new uptodate buffers to
                                         * ->write_end() time or
                                         * folio_zero_new_buffers().
                                         */
                                        set_buffer_uptodate(bh);
                                        continue;
                                }
                                if (block_end > to || block_start < from)
                                        folio_zero_segments(folio, to,
                                                            block_end,
                                                            block_start, from);
                                continue;
                        }
                }
                if (folio_test_uptodate(folio)) {
                        set_buffer_uptodate(bh);
                        continue;
                }
                if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
                    !buffer_unwritten(bh) &&
                    (block_start < from || block_end > to)) {
                        ext4_read_bh_lock(bh, 0, false);
                        wait[nr_wait++] = bh;
                }
        }
        /*
         * If we issued read requests, let them complete.
         */
        for (i = 0; i < nr_wait; i++) {
                wait_on_buffer(wait[i]);
                if (!buffer_uptodate(wait[i]))
                        err = -EIO;
        }
        if (unlikely(err)) {
                if (should_journal_data)
                        ext4_journalled_zero_new_buffers(handle, inode, folio,
                                                         from, to);
                else
                        folio_zero_new_buffers(folio, from, to);
        } else if (fscrypt_inode_uses_fs_layer_crypto(inode)) {
                for (i = 0; i < nr_wait; i++) {
                        int err2;

                        err2 = fscrypt_decrypt_pagecache_blocks(folio,
                                                blocksize, bh_offset(wait[i]));
                        if (err2) {
                                clear_buffer_uptodate(wait[i]);
                                err = err2;
                        }
                }
        }

        return err;
}

/*
 * To preserve ordering, it is essential that the hole instantiation and
 * the data write be encapsulated in a single transaction.  We cannot
 * close off a transaction and start a new one between the ext4_get_block()
 * and the ext4_write_end().  So doing the jbd2_journal_start at the start of
 * ext4_write_begin() is the right place.
 */
static int ext4_write_begin(const struct kiocb *iocb,
                            struct address_space *mapping,
                            loff_t pos, unsigned len,
                            struct folio **foliop, void **fsdata)
{
        struct inode *inode = mapping->host;
        int ret, needed_blocks;
        handle_t *handle;
        int retries = 0;
        struct folio *folio;
        pgoff_t index;
        unsigned from, to;

        ret = ext4_emergency_state(inode->i_sb);
        if (unlikely(ret))
                return ret;

        trace_ext4_write_begin(inode, pos, len);
        /*
         * Reserve one block more for addition to orphan list in case
         * we allocate blocks but write fails for some reason
         */
        needed_blocks = ext4_chunk_trans_extent(inode,
                        ext4_journal_blocks_per_folio(inode)) + 1;
        index = pos >> PAGE_SHIFT;

        if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
                ret = ext4_try_to_write_inline_data(mapping, inode, pos, len,
                                                    foliop);
                if (ret < 0)
                        return ret;
                if (ret == 1)
                        return 0;
        }

        /*
         * write_begin_get_folio() can take a long time if the
         * system is thrashing due to memory pressure, or if the folio
         * is being written back.  So grab it first before we start
         * the transaction handle.  This also allows us to allocate
         * the folio (if needed) without using GFP_NOFS.
         */
retry_grab:
        folio = write_begin_get_folio(iocb, mapping, index, len);
        if (IS_ERR(folio))
                return PTR_ERR(folio);

        if (len > folio_next_pos(folio) - pos)
                len = folio_next_pos(folio) - pos;

        from = offset_in_folio(folio, pos);
        to = from + len;

        /*
         * The same as page allocation, we prealloc buffer heads before
         * starting the handle.
         */
        if (!folio_buffers(folio))
                create_empty_buffers(folio, inode->i_sb->s_blocksize, 0);

        folio_unlock(folio);

retry_journal:
        handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, needed_blocks);
        if (IS_ERR(handle)) {
                folio_put(folio);
                return PTR_ERR(handle);
        }

        folio_lock(folio);
        if (folio->mapping != mapping) {
                /* The folio got truncated from under us */
                folio_unlock(folio);
                folio_put(folio);
                ext4_journal_stop(handle);
                goto retry_grab;
        }
        /* In case writeback began while the folio was unlocked */
        folio_wait_stable(folio);

        if (ext4_should_dioread_nolock(inode))
                ret = ext4_block_write_begin(handle, folio, pos, len,
                                             ext4_get_block_unwritten);
        else
                ret = ext4_block_write_begin(handle, folio, pos, len,
                                             ext4_get_block);
        if (!ret && ext4_should_journal_data(inode)) {
                ret = ext4_walk_page_buffers(handle, inode,
                                             folio_buffers(folio), from, to,
                                             NULL, do_journal_get_write_access);
        }

        if (ret) {
                bool extended = (pos + len > inode->i_size) &&
                                !ext4_verity_in_progress(inode);

                folio_unlock(folio);
                /*
                 * ext4_block_write_begin may have instantiated a few blocks
                 * outside i_size.  Trim these off again. Don't need
                 * i_size_read because we hold i_rwsem.
                 *
                 * Add inode to orphan list in case we crash before
                 * truncate finishes
                 */
                if (extended && ext4_can_truncate(inode))
                        ext4_orphan_add(handle, inode);

                ext4_journal_stop(handle);
                if (extended) {
                        ext4_truncate_failed_write(inode);
                        /*
                         * If truncate failed early the inode might
                         * still be on the orphan list; we need to
                         * make sure the inode is removed from the
                         * orphan list in that case.
                         */
                        if (inode->i_nlink)
                                ext4_orphan_del(NULL, inode);
                }

                if (ret == -EAGAIN ||
                    (ret == -ENOSPC &&
                     ext4_should_retry_alloc(inode->i_sb, &retries)))
                        goto retry_journal;
                folio_put(folio);
                return ret;
        }
        *foliop = folio;
        return ret;
}

/* For write_end() in data=journal mode */
static int write_end_fn(handle_t *handle, struct inode *inode,
                        struct buffer_head *bh)
{
        int ret;
        if (!buffer_mapped(bh) || buffer_freed(bh))
                return 0;
        set_buffer_uptodate(bh);
        ret = ext4_dirty_journalled_data(handle, bh);
        clear_buffer_meta(bh);
        clear_buffer_prio(bh);
        clear_buffer_new(bh);
        return ret;
}

/*
 * We need to pick up the new inode size which generic_commit_write gave us
 * `iocb` can be NULL - eg, when called from page_symlink().
 *
 * ext4 never places buffers on inode->i_mapping->i_private_list.  metadata
 * buffers are managed internally.
 */
static int ext4_write_end(const struct kiocb *iocb,
                          struct address_space *mapping,
                          loff_t pos, unsigned len, unsigned copied,
                          struct folio *folio, void *fsdata)
{
        handle_t *handle = ext4_journal_current_handle();
        struct inode *inode = mapping->host;
        loff_t old_size = inode->i_size;
        int ret = 0, ret2;
        int i_size_changed = 0;
        bool verity = ext4_verity_in_progress(inode);

        trace_ext4_write_end(inode, pos, len, copied);

        if (ext4_has_inline_data(inode) &&
            ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA))
                return ext4_write_inline_data_end(inode, pos, len, copied,
                                                  folio);

        copied = block_write_end(pos, len, copied, folio);
        /*
         * it's important to update i_size while still holding folio lock:
         * page writeout could otherwise come in and zero beyond i_size.
         *
         * If FS_IOC_ENABLE_VERITY is running on this inode, then Merkle tree
         * blocks are being written past EOF, so skip the i_size update.
         */
        if (!verity)
                i_size_changed = ext4_update_inode_size(inode, pos + copied);
        folio_unlock(folio);
        folio_put(folio);

        if (old_size < pos && !verity) {
                pagecache_isize_extended(inode, old_size, pos);
                ext4_zero_partial_blocks(handle, inode, old_size, pos - old_size);
        }
        /*
         * Don't mark the inode dirty under folio lock. First, it unnecessarily
         * makes the holding time of folio lock longer. Second, it forces lock
         * ordering of folio lock and transaction start for journaling
         * filesystems.
         */
        if (i_size_changed)
                ret = ext4_mark_inode_dirty(handle, inode);

        if (pos + len > inode->i_size && !verity && ext4_can_truncate(inode))
                /* if we have allocated more blocks and copied
                 * less. We will have blocks allocated outside
                 * inode->i_size. So truncate them
                 */
                ext4_orphan_add(handle, inode);

        ret2 = ext4_journal_stop(handle);
        if (!ret)
                ret = ret2;

        if (pos + len > inode->i_size && !verity) {
                ext4_truncate_failed_write(inode);
                /*
                 * If truncate failed early the inode might still be
                 * on the orphan list; we need to make sure the inode
                 * is removed from the orphan list in that case.
                 */
                if (inode->i_nlink)
                        ext4_orphan_del(NULL, inode);
        }

        return ret ? ret : copied;
}

/*
 * This is a private version of folio_zero_new_buffers() which doesn't
 * set the buffer to be dirty, since in data=journalled mode we need
 * to call ext4_dirty_journalled_data() instead.
 */
static void ext4_journalled_zero_new_buffers(handle_t *handle,
                                            struct inode *inode,
                                            struct folio *folio,
                                            unsigned from, unsigned to)
{
        unsigned int block_start = 0, block_end;
        struct buffer_head *head, *bh;

        bh = head = folio_buffers(folio);
        do {
                block_end = block_start + bh->b_size;
                if (buffer_new(bh)) {
                        if (block_end > from && block_start < to) {
                                if (!folio_test_uptodate(folio)) {
                                        unsigned start, size;

                                        start = max(from, block_start);
                                        size = min(to, block_end) - start;

                                        folio_zero_range(folio, start, size);
                                }
                                clear_buffer_new(bh);
                                write_end_fn(handle, inode, bh);
                        }
                }
                block_start = block_end;
                bh = bh->b_this_page;
        } while (bh != head);
}

static int ext4_journalled_write_end(const struct kiocb *iocb,
                                     struct address_space *mapping,
                                     loff_t pos, unsigned len, unsigned copied,
                                     struct folio *folio, void *fsdata)
{
        handle_t *handle = ext4_journal_current_handle();
        struct inode *inode = mapping->host;
        loff_t old_size = inode->i_size;
        int ret = 0, ret2;
        int partial = 0;
        unsigned from, to;
        int size_changed = 0;
        bool verity = ext4_verity_in_progress(inode);

        trace_ext4_journalled_write_end(inode, pos, len, copied);
        from = pos & (PAGE_SIZE - 1);
        to = from + len;

        BUG_ON(!ext4_handle_valid(handle));

        if (ext4_has_inline_data(inode))
                return ext4_write_inline_data_end(inode, pos, len, copied,
                                                  folio);

        if (unlikely(copied < len) && !folio_test_uptodate(folio)) {
                copied = 0;
                ext4_journalled_zero_new_buffers(handle, inode, folio,
                                                 from, to);
        } else {
                if (unlikely(copied < len))
                        ext4_journalled_zero_new_buffers(handle, inode, folio,
                                                         from + copied, to);
                ret = ext4_walk_page_buffers(handle, inode,
                                             folio_buffers(folio),
                                             from, from + copied, &partial,
                                             write_end_fn);
                if (!partial)
                        folio_mark_uptodate(folio);
        }
        if (!verity)
                size_changed = ext4_update_inode_size(inode, pos + copied);
        EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
        folio_unlock(folio);
        folio_put(folio);

        if (old_size < pos && !verity) {
                pagecache_isize_extended(inode, old_size, pos);
                ext4_zero_partial_blocks(handle, inode, old_size, pos - old_size);
        }

        if (size_changed) {
                ret2 = ext4_mark_inode_dirty(handle, inode);
                if (!ret)
                        ret = ret2;
        }

        if (pos + len > inode->i_size && !verity && ext4_can_truncate(inode))
                /* if we have allocated more blocks and copied
                 * less. We will have blocks allocated outside
                 * inode->i_size. So truncate them
                 */
                ext4_orphan_add(handle, inode);

        ret2 = ext4_journal_stop(handle);
        if (!ret)
                ret = ret2;
        if (pos + len > inode->i_size && !verity) {
                ext4_truncate_failed_write(inode);
                /*
                 * If truncate failed early the inode might still be
                 * on the orphan list; we need to make sure the inode
                 * is removed from the orphan list in that case.
                 */
                if (inode->i_nlink)
                        ext4_orphan_del(NULL, inode);
        }

        return ret ? ret : copied;
}

/*
 * Reserve space for 'nr_resv' clusters
 */
static int ext4_da_reserve_space(struct inode *inode, int nr_resv)
{
        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
        struct ext4_inode_info *ei = EXT4_I(inode);
        int ret;

        /*
         * We will charge metadata quota at writeout time; this saves
         * us from metadata over-estimation, though we may go over by
         * a small amount in the end.  Here we just reserve for data.
         */
        ret = dquot_reserve_block(inode, EXT4_C2B(sbi, nr_resv));
        if (ret)
                return ret;

        spin_lock(&ei->i_block_reservation_lock);
        if (ext4_claim_free_clusters(sbi, nr_resv, 0)) {
                spin_unlock(&ei->i_block_reservation_lock);
                dquot_release_reservation_block(inode, EXT4_C2B(sbi, nr_resv));
                return -ENOSPC;
        }
        ei->i_reserved_data_blocks += nr_resv;
        trace_ext4_da_reserve_space(inode, nr_resv);
        spin_unlock(&ei->i_block_reservation_lock);

        return 0;       /* success */
}

void ext4_da_release_space(struct inode *inode, int to_free)
{
        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
        struct ext4_inode_info *ei = EXT4_I(inode);

        if (!to_free)
                return;         /* Nothing to release, exit */

        spin_lock(&EXT4_I(inode)->i_block_reservation_lock);

        trace_ext4_da_release_space(inode, to_free);
        if (unlikely(to_free > ei->i_reserved_data_blocks)) {
                /*
                 * if there aren't enough reserved blocks, then the
                 * counter is messed up somewhere.  Since this
                 * function is called from invalidate page, it's
                 * harmless to return without any action.
                 */
                ext4_warning(inode->i_sb, "ext4_da_release_space: "
                         "ino %lu, to_free %d with only %d reserved "
                         "data blocks", inode->i_ino, to_free,
                         ei->i_reserved_data_blocks);
                WARN_ON(1);
                to_free = ei->i_reserved_data_blocks;
        }
        ei->i_reserved_data_blocks -= to_free;

        /* update fs dirty data blocks counter */
        percpu_counter_sub(&sbi->s_dirtyclusters_counter, to_free);

        spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);

        dquot_release_reservation_block(inode, EXT4_C2B(sbi, to_free));
}

/*
 * Delayed allocation stuff
 */

struct mpage_da_data {
        /* These are input fields for ext4_do_writepages() */
        struct inode *inode;
        struct writeback_control *wbc;
        unsigned int can_map:1; /* Can writepages call map blocks? */

        /* These are internal state of ext4_do_writepages() */
        loff_t start_pos;       /* The start pos to write */
        loff_t next_pos;        /* Current pos to examine */
        loff_t end_pos;         /* Last pos to examine */

        /*
         * Extent to map - this can be after start_pos because that can be
         * fully mapped. We somewhat abuse m_flags to store whether the extent
         * is delalloc or unwritten.
         */
        struct ext4_map_blocks map;
        struct ext4_io_submit io_submit;        /* IO submission data */
        unsigned int do_map:1;
        unsigned int scanned_until_end:1;
        unsigned int journalled_more_data:1;
};

static void mpage_release_unused_pages(struct mpage_da_data *mpd,
                                       bool invalidate)
{
        unsigned nr, i;
        pgoff_t index, end;
        struct folio_batch fbatch;
        struct inode *inode = mpd->inode;
        struct address_space *mapping = inode->i_mapping;

        /* This is necessary when next_pos == 0. */
        if (mpd->start_pos >= mpd->next_pos)
                return;

        mpd->scanned_until_end = 0;
        if (invalidate) {
                ext4_lblk_t start, last;
                start = EXT4_B_TO_LBLK(inode, mpd->start_pos);
                last = mpd->next_pos >> inode->i_blkbits;

                /*
                 * avoid racing with extent status tree scans made by
                 * ext4_insert_delayed_block()
                 */
                down_write(&EXT4_I(inode)->i_data_sem);
                ext4_es_remove_extent(inode, start, last - start);
                up_write(&EXT4_I(inode)->i_data_sem);
        }

        folio_batch_init(&fbatch);
        index = mpd->start_pos >> PAGE_SHIFT;
        end = mpd->next_pos >> PAGE_SHIFT;
        while (index < end) {
                nr = filemap_get_folios(mapping, &index, end - 1, &fbatch);
                if (nr == 0)
                        break;
                for (i = 0; i < nr; i++) {
                        struct folio *folio = fbatch.folios[i];

                        if (folio_pos(folio) < mpd->start_pos)
                                continue;
                        if (folio_next_index(folio) > end)
                                continue;
                        BUG_ON(!folio_test_locked(folio));
                        BUG_ON(folio_test_writeback(folio));
                        if (invalidate) {
                                if (folio_mapped(folio))
                                        folio_clear_dirty_for_io(folio);
                                block_invalidate_folio(folio, 0,
                                                folio_size(folio));
                                folio_clear_uptodate(folio);
                        }
                        folio_unlock(folio);
                }
                folio_batch_release(&fbatch);
        }
}

static void ext4_print_free_blocks(struct inode *inode)
{
        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
        struct super_block *sb = inode->i_sb;
        struct ext4_inode_info *ei = EXT4_I(inode);

        ext4_msg(sb, KERN_CRIT, "Total free blocks count %lld",
               EXT4_C2B(EXT4_SB(inode->i_sb),
                        ext4_count_free_clusters(sb)));
        ext4_msg(sb, KERN_CRIT, "Free/Dirty block details");
        ext4_msg(sb, KERN_CRIT, "free_blocks=%lld",
               (long long) EXT4_C2B(EXT4_SB(sb),
                percpu_counter_sum(&sbi->s_freeclusters_counter)));
        ext4_msg(sb, KERN_CRIT, "dirty_blocks=%lld",
               (long long) EXT4_C2B(EXT4_SB(sb),
                percpu_counter_sum(&sbi->s_dirtyclusters_counter)));
        ext4_msg(sb, KERN_CRIT, "Block reservation details");
        ext4_msg(sb, KERN_CRIT, "i_reserved_data_blocks=%u",
                 ei->i_reserved_data_blocks);
        return;
}

/*
 * Check whether the cluster containing lblk has been allocated or has
 * delalloc reservation.
 *
 * Returns 0 if the cluster doesn't have either, 1 if it has delalloc
 * reservation, 2 if it's already been allocated, negative error code on
 * failure.
 */
static int ext4_clu_alloc_state(struct inode *inode, ext4_lblk_t lblk)
{
        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
        int ret;

        /* Has delalloc reservation? */
        if (ext4_es_scan_clu(inode, &ext4_es_is_delayed, lblk))
                return 1;

        /* Already been allocated? */
        if (ext4_es_scan_clu(inode, &ext4_es_is_mapped, lblk))
                return 2;
        ret = ext4_clu_mapped(inode, EXT4_B2C(sbi, lblk));
        if (ret < 0)
                return ret;
        if (ret > 0)
                return 2;

        return 0;
}

/*
 * ext4_insert_delayed_blocks - adds a multiple delayed blocks to the extents
 *                              status tree, incrementing the reserved
 *                              cluster/block count or making pending
 *                              reservations where needed
 *
 * @inode - file containing the newly added block
 * @lblk - start logical block to be added
 * @len - length of blocks to be added
 *
 * Returns 0 on success, negative error code on failure.
 */
static int ext4_insert_delayed_blocks(struct inode *inode, ext4_lblk_t lblk,
                                      ext4_lblk_t len)
{
        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
        int ret;
        bool lclu_allocated = false;
        bool end_allocated = false;
        ext4_lblk_t resv_clu;
        ext4_lblk_t end = lblk + len - 1;

        /*
         * If the cluster containing lblk or end is shared with a delayed,
         * written, or unwritten extent in a bigalloc file system, it's
         * already been accounted for and does not need to be reserved.
         * A pending reservation must be made for the cluster if it's
         * shared with a written or unwritten extent and doesn't already
         * have one.  Written and unwritten extents can be purged from the
         * extents status tree if the system is under memory pressure, so
         * it's necessary to examine the extent tree if a search of the
         * extents status tree doesn't get a match.
         */
        if (sbi->s_cluster_ratio == 1) {
                ret = ext4_da_reserve_space(inode, len);
                if (ret != 0)   /* ENOSPC */
                        return ret;
        } else {   /* bigalloc */
                resv_clu = EXT4_B2C(sbi, end) - EXT4_B2C(sbi, lblk) + 1;

                ret = ext4_clu_alloc_state(inode, lblk);
                if (ret < 0)
                        return ret;
                if (ret > 0) {
                        resv_clu--;
                        lclu_allocated = (ret == 2);
                }

                if (EXT4_B2C(sbi, lblk) != EXT4_B2C(sbi, end)) {
                        ret = ext4_clu_alloc_state(inode, end);
                        if (ret < 0)
                                return ret;
                        if (ret > 0) {
                                resv_clu--;
                                end_allocated = (ret == 2);
                        }
                }

                if (resv_clu) {
                        ret = ext4_da_reserve_space(inode, resv_clu);
                        if (ret != 0)   /* ENOSPC */
                                return ret;
                }
        }

        ext4_es_insert_delayed_extent(inode, lblk, len, lclu_allocated,
                                      end_allocated);
        return 0;
}

/*
 * Looks up the requested blocks and sets the delalloc extent map.
 * First try to look up for the extent entry that contains the requested
 * blocks in the extent status tree without i_data_sem, then try to look
 * up for the ondisk extent mapping with i_data_sem in read mode,
 * finally hold i_data_sem in write mode, looks up again and add a
 * delalloc extent entry if it still couldn't find any extent. Pass out
 * the mapped extent through @map and return 0 on success.
 */
static int ext4_da_map_blocks(struct inode *inode, struct ext4_map_blocks *map)
{
        struct extent_status es;
        int retval;
#ifdef ES_AGGRESSIVE_TEST
        struct ext4_map_blocks orig_map;

        memcpy(&orig_map, map, sizeof(*map));
#endif

        map->m_flags = 0;
        ext_debug(inode, "max_blocks %u, logical block %lu\n", map->m_len,
                  (unsigned long) map->m_lblk);

        ext4_check_map_extents_env(inode);

        /* Lookup extent status tree firstly */
        if (ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es, NULL)) {
                map->m_len = min_t(unsigned int, map->m_len,
                                   es.es_len - (map->m_lblk - es.es_lblk));

                if (ext4_es_is_hole(&es))
                        goto add_delayed;

found:
                /*
                 * Delayed extent could be allocated by fallocate.
                 * So we need to check it.
                 */
                if (ext4_es_is_delayed(&es)) {
                        map->m_flags |= EXT4_MAP_DELAYED;
                        return 0;
                }

                map->m_pblk = ext4_es_pblock(&es) + map->m_lblk - es.es_lblk;
                if (ext4_es_is_written(&es))
                        map->m_flags |= EXT4_MAP_MAPPED;
                else if (ext4_es_is_unwritten(&es))
                        map->m_flags |= EXT4_MAP_UNWRITTEN;
                else
                        BUG();

#ifdef ES_AGGRESSIVE_TEST
                ext4_map_blocks_es_recheck(NULL, inode, map, &orig_map, 0);
#endif
                return 0;
        }

        /*
         * Try to see if we can get the block without requesting a new
         * file system block.
         */
        down_read(&EXT4_I(inode)->i_data_sem);
        if (ext4_has_inline_data(inode))
                retval = 0;
        else
                retval = ext4_map_query_blocks(NULL, inode, map, 0);
        up_read(&EXT4_I(inode)->i_data_sem);
        if (retval)
                return retval < 0 ? retval : 0;

add_delayed:
        down_write(&EXT4_I(inode)->i_data_sem);
        /*
         * Page fault path (ext4_page_mkwrite does not take i_rwsem)
         * and fallocate path (no folio lock) can race. Make sure we
         * lookup the extent status tree here again while i_data_sem
         * is held in write mode, before inserting a new da entry in
         * the extent status tree.
         */
        if (ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es, NULL)) {
                map->m_len = min_t(unsigned int, map->m_len,
                                   es.es_len - (map->m_lblk - es.es_lblk));

                if (!ext4_es_is_hole(&es)) {
                        up_write(&EXT4_I(inode)->i_data_sem);
                        goto found;
                }
        } else if (!ext4_has_inline_data(inode)) {
                retval = ext4_map_query_blocks(NULL, inode, map, 0);
                if (retval) {
                        up_write(&EXT4_I(inode)->i_data_sem);
                        return retval < 0 ? retval : 0;
                }
        }

        map->m_flags |= EXT4_MAP_DELAYED;
        retval = ext4_insert_delayed_blocks(inode, map->m_lblk, map->m_len);
        if (!retval)
                map->m_seq = READ_ONCE(EXT4_I(inode)->i_es_seq);
        up_write(&EXT4_I(inode)->i_data_sem);

        return retval;
}

/*
 * This is a special get_block_t callback which is used by
 * ext4_da_write_begin().  It will either return mapped block or
 * reserve space for a single block.
 *
 * For delayed buffer_head we have BH_Mapped, BH_New, BH_Delay set.
 * We also have b_blocknr = -1 and b_bdev initialized properly
 *
 * For unwritten buffer_head we have BH_Mapped, BH_New, BH_Unwritten set.
 * We also have b_blocknr = physicalblock mapping unwritten extent and b_bdev
 * initialized properly.
 */
int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
                           struct buffer_head *bh, int create)
{
        struct ext4_map_blocks map;
        sector_t invalid_block = ~((sector_t) 0xffff);
        int ret = 0;

        BUG_ON(create == 0);
        BUG_ON(bh->b_size != inode->i_sb->s_blocksize);

        if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es))
                invalid_block = ~0;

        map.m_lblk = iblock;
        map.m_len = 1;

        /*
         * first, we need to know whether the block is allocated already
         * preallocated blocks are unmapped but should treated
         * the same as allocated blocks.
         */
        ret = ext4_da_map_blocks(inode, &map);
        if (ret < 0)
                return ret;

        if (map.m_flags & EXT4_MAP_DELAYED) {
                map_bh(bh, inode->i_sb, invalid_block);
                set_buffer_new(bh);
                set_buffer_delay(bh);
                return 0;
        }

        map_bh(bh, inode->i_sb, map.m_pblk);
        ext4_update_bh_state(bh, map.m_flags);

        if (buffer_unwritten(bh)) {
                /* A delayed write to unwritten bh should be marked
                 * new and mapped.  Mapped ensures that we don't do
                 * get_block multiple times when we write to the same
                 * offset and new ensures that we do proper zero out
                 * for partial write.
                 */
                set_buffer_new(bh);
                set_buffer_mapped(bh);
        }
        return 0;
}

static void mpage_folio_done(struct mpage_da_data *mpd, struct folio *folio)
{
        mpd->start_pos += folio_size(folio);
        mpd->wbc->nr_to_write -= folio_nr_pages(folio);
        folio_unlock(folio);
}

static int mpage_submit_folio(struct mpage_da_data *mpd, struct folio *folio)
{
        size_t len;
        loff_t size;
        int err;

        WARN_ON_ONCE(folio_pos(folio) != mpd->start_pos);
        folio_clear_dirty_for_io(folio);
        /*
         * We have to be very careful here!  Nothing protects writeback path
         * against i_size changes and the page can be writeably mapped into
         * page tables. So an application can be growing i_size and writing
         * data through mmap while writeback runs. folio_clear_dirty_for_io()
         * write-protects our page in page tables and the page cannot get
         * written to again until we release folio lock. So only after
         * folio_clear_dirty_for_io() we are safe to sample i_size for
         * ext4_bio_write_folio() to zero-out tail of the written page. We rely
         * on the barrier provided by folio_test_clear_dirty() in
         * folio_clear_dirty_for_io() to make sure i_size is really sampled only
         * after page tables are updated.
         */
        size = i_size_read(mpd->inode);
        len = folio_size(folio);
        if (folio_pos(folio) + len > size &&
            !ext4_verity_in_progress(mpd->inode))
                len = size & (len - 1);
        err = ext4_bio_write_folio(&mpd->io_submit, folio, len);

        return err;
}

#define BH_FLAGS (BIT(BH_Unwritten) | BIT(BH_Delay))

/*
 * mballoc gives us at most this number of blocks...
 * XXX: That seems to be only a limitation of ext4_mb_normalize_request().
 * The rest of mballoc seems to handle chunks up to full group size.
 */
#define MAX_WRITEPAGES_EXTENT_LEN 2048

/*
 * mpage_add_bh_to_extent - try to add bh to extent of blocks to map
 *
 * @mpd - extent of blocks
 * @lblk - logical number of the block in the file
 * @bh - buffer head we want to add to the extent
 *
 * The function is used to collect contig. blocks in the same state. If the
 * buffer doesn't require mapping for writeback and we haven't started the
 * extent of buffers to map yet, the function returns 'true' immediately - the
 * caller can write the buffer right away. Otherwise the function returns true
 * if the block has been added to the extent, false if the block couldn't be
 * added.
 */
static bool mpage_add_bh_to_extent(struct mpage_da_data *mpd, ext4_lblk_t lblk,
                                   struct buffer_head *bh)
{
        struct ext4_map_blocks *map = &mpd->map;

        /* Buffer that doesn't need mapping for writeback? */
        if (!buffer_dirty(bh) || !buffer_mapped(bh) ||
            (!buffer_delay(bh) && !buffer_unwritten(bh))) {
                /* So far no extent to map => we write the buffer right away */
                if (map->m_len == 0)
                        return true;
                return false;
        }

        /* First block in the extent? */
        if (map->m_len == 0) {
                /* We cannot map unless handle is started... */
                if (!mpd->do_map)
                        return false;
                map->m_lblk = lblk;
                map->m_len = 1;
                map->m_flags = bh->b_state & BH_FLAGS;
                return true;
        }

        /* Don't go larger than mballoc is willing to allocate */
        if (map->m_len >= MAX_WRITEPAGES_EXTENT_LEN)
                return false;

        /* Can we merge the block to our big extent? */
        if (lblk == map->m_lblk + map->m_len &&
            (bh->b_state & BH_FLAGS) == map->m_flags) {
                map->m_len++;
                return true;
        }
        return false;
}

/*
 * mpage_process_page_bufs - submit page buffers for IO or add them to extent
 *
 * @mpd - extent of blocks for mapping
 * @head - the first buffer in the page
 * @bh - buffer we should start processing from
 * @lblk - logical number of the block in the file corresponding to @bh
 *
 * Walk through page buffers from @bh upto @head (exclusive) and either submit
 * the page for IO if all buffers in this page were mapped and there's no
 * accumulated extent of buffers to map or add buffers in the page to the
 * extent of buffers to map. The function returns 1 if the caller can continue
 * by processing the next page, 0 if it should stop adding buffers to the
 * extent to map because we cannot extend it anymore. It can also return value
 * < 0 in case of error during IO submission.
 */
static int mpage_process_page_bufs(struct mpage_da_data *mpd,
                                   struct buffer_head *head,
                                   struct buffer_head *bh,
                                   ext4_lblk_t lblk)
{
        struct inode *inode = mpd->inode;
        int err;
        ext4_lblk_t blocks = (i_size_read(inode) + i_blocksize(inode) - 1)
                                                        >> inode->i_blkbits;

        if (ext4_verity_in_progress(inode))
                blocks = EXT_MAX_BLOCKS;

        do {
                BUG_ON(buffer_locked(bh));

                if (lblk >= blocks || !mpage_add_bh_to_extent(mpd, lblk, bh)) {
                        /* Found extent to map? */
                        if (mpd->map.m_len)
                                return 0;
                        /* Buffer needs mapping and handle is not started? */
                        if (!mpd->do_map)
                                return 0;
                        /* Everything mapped so far and we hit EOF */
                        break;
                }
        } while (lblk++, (bh = bh->b_this_page) != head);
        /* So far everything mapped? Submit the page for IO. */
        if (mpd->map.m_len == 0) {
                err = mpage_submit_folio(mpd, head->b_folio);
                if (err < 0)
                        return err;
                mpage_folio_done(mpd, head->b_folio);
        }
        if (lblk >= blocks) {
                mpd->scanned_until_end = 1;
                return 0;
        }
        return 1;
}

/*
 * mpage_process_folio - update folio buffers corresponding to changed extent
 *                       and may submit fully mapped page for IO
 * @mpd: description of extent to map, on return next extent to map
 * @folio: Contains these buffers.
 * @m_lblk: logical block mapping.
 * @m_pblk: corresponding physical mapping.
 * @map_bh: determines on return whether this page requires any further
 *                mapping or not.
 *
 * Scan given folio buffers corresponding to changed extent and update buffer
 * state according to new extent state.
 * We map delalloc buffers to their physical location, clear unwritten bits.
 * If the given folio is not fully mapped, we update @mpd to the next extent in
 * the given folio that needs mapping & return @map_bh as true.
 */
static int mpage_process_folio(struct mpage_da_data *mpd, struct folio *folio,
                              ext4_lblk_t *m_lblk, ext4_fsblk_t *m_pblk,
                              bool *map_bh)
{
        struct buffer_head *head, *bh;
        ext4_io_end_t *io_end = mpd->io_submit.io_end;
        ext4_lblk_t lblk = *m_lblk;
        ext4_fsblk_t pblock = *m_pblk;
        int err = 0;
        ssize_t io_end_size = 0;
        struct ext4_io_end_vec *io_end_vec = ext4_last_io_end_vec(io_end);

        bh = head = folio_buffers(folio);
        do {
                if (lblk < mpd->map.m_lblk)
                        continue;
                if (lblk >= mpd->map.m_lblk + mpd->map.m_len) {
                        /*
                         * Buffer after end of mapped extent.
                         * Find next buffer in the folio to map.
                         */
                        mpd->map.m_len = 0;
                        mpd->map.m_flags = 0;
                        io_end_vec->size += io_end_size;

                        err = mpage_process_page_bufs(mpd, head, bh, lblk);
                        if (err > 0)
                                err = 0;
                        if (!err && mpd->map.m_len && mpd->map.m_lblk > lblk) {
                                io_end_vec = ext4_alloc_io_end_vec(io_end);
                                if (IS_ERR(io_end_vec)) {
                                        err = PTR_ERR(io_end_vec);
                                        goto out;
                                }
                                io_end_vec->offset = EXT4_LBLK_TO_B(mpd->inode,
                                                                mpd->map.m_lblk);
                        }
                        *map_bh = true;
                        goto out;
                }
                if (buffer_delay(bh)) {
                        clear_buffer_delay(bh);
                        bh->b_blocknr = pblock++;
                }
                clear_buffer_unwritten(bh);
                io_end_size += i_blocksize(mpd->inode);
        } while (lblk++, (bh = bh->b_this_page) != head);

        io_end_vec->size += io_end_size;
        *map_bh = false;
out:
        *m_lblk = lblk;
        *m_pblk = pblock;
        return err;
}

/*
 * mpage_map_buffers - update buffers corresponding to changed extent and
 *                     submit fully mapped pages for IO
 *
 * @mpd - description of extent to map, on return next extent to map
 *
 * Scan buffers corresponding to changed extent (we expect corresponding pages
 * to be already locked) and update buffer state according to new extent state.
 * We map delalloc buffers to their physical location, clear unwritten bits,
 * and mark buffers as uninit when we perform writes to unwritten extents
 * and do extent conversion after IO is finished. If the last page is not fully
 * mapped, we update @map to the next extent in the last page that needs
 * mapping. Otherwise we submit the page for IO.
 */
static int mpage_map_and_submit_buffers(struct mpage_da_data *mpd)
{
        struct folio_batch fbatch;
        unsigned nr, i;
        struct inode *inode = mpd->inode;
        pgoff_t start, end;
        ext4_lblk_t lblk;
        ext4_fsblk_t pblock;
        int err;
        bool map_bh = false;

        start = EXT4_LBLK_TO_PG(inode, mpd->map.m_lblk);
        end = EXT4_LBLK_TO_PG(inode, mpd->map.m_lblk + mpd->map.m_len - 1);
        pblock = mpd->map.m_pblk;

        folio_batch_init(&fbatch);
        while (start <= end) {
                nr = filemap_get_folios(inode->i_mapping, &start, end, &fbatch);
                if (nr == 0)
                        break;
                for (i = 0; i < nr; i++) {
                        struct folio *folio = fbatch.folios[i];

                        lblk = EXT4_PG_TO_LBLK(inode, folio->index);
                        err = mpage_process_folio(mpd, folio, &lblk, &pblock,
                                                 &map_bh);
                        /*
                         * If map_bh is true, means page may require further bh
                         * mapping, or maybe the page was submitted for IO.
                         * So we return to call further extent mapping.
                         */
                        if (err < 0 || map_bh)
                                goto out;
                        /* Page fully mapped - let IO run! */
                        err = mpage_submit_folio(mpd, folio);
                        if (err < 0)
                                goto out;
                        mpage_folio_done(mpd, folio);
                }
                folio_batch_release(&fbatch);
        }
        /* Extent fully mapped and matches with page boundary. We are done. */
        mpd->map.m_len = 0;
        mpd->map.m_flags = 0;
        return 0;
out:
        folio_batch_release(&fbatch);
        return err;
}

static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd)
{
        struct inode *inode = mpd->inode;
        struct ext4_map_blocks *map = &mpd->map;
        int get_blocks_flags;
        int err, dioread_nolock;

        /* Make sure transaction has enough credits for this extent */
        err = ext4_journal_ensure_extent_credits(handle, inode);
        if (err < 0)
                return err;

        trace_ext4_da_write_pages_extent(inode, map);
        /*
         * Call ext4_map_blocks() to allocate any delayed allocation blocks, or
         * to convert an unwritten extent to be initialized (in the case
         * where we have written into one or more preallocated blocks).  It is
         * possible that we're going to need more metadata blocks than
         * previously reserved. However we must not fail because we're in
         * writeback and there is nothing we can do about it so it might result
         * in data loss.  So use reserved blocks to allocate metadata if
         * possible. In addition, do not cache any unrelated extents, as it
         * only holds the folio lock but does not hold the i_rwsem or
         * invalidate_lock, which could corrupt the extent status tree.
         */
        get_blocks_flags = EXT4_GET_BLOCKS_CREATE |
                           EXT4_GET_BLOCKS_METADATA_NOFAIL |
                           EXT4_GET_BLOCKS_IO_SUBMIT |
                           EXT4_EX_NOCACHE;

        dioread_nolock = ext4_should_dioread_nolock(inode);
        if (dioread_nolock)
                get_blocks_flags |= EXT4_GET_BLOCKS_UNWRIT_EXT;

        err = ext4_map_blocks(handle, inode, map, get_blocks_flags);
        if (err < 0)
                return err;
        if (dioread_nolock && (map->m_flags & EXT4_MAP_UNWRITTEN)) {
                if (!mpd->io_submit.io_end->handle &&
                    ext4_handle_valid(handle)) {
                        mpd->io_submit.io_end->handle = handle->h_rsv_handle;
                        handle->h_rsv_handle = NULL;
                }
                ext4_set_io_unwritten_flag(mpd->io_submit.io_end);
        }

        BUG_ON(map->m_len == 0);
        return 0;
}

/*
 * This is used to submit mapped buffers in a single folio that is not fully
 * mapped for various reasons, such as insufficient space or journal credits.
 */
static int mpage_submit_partial_folio(struct mpage_da_data *mpd)
{
        struct inode *inode = mpd->inode;
        struct folio *folio;
        loff_t pos;
        int ret;

        folio = filemap_get_folio(inode->i_mapping,
                                  mpd->start_pos >> PAGE_SHIFT);
        if (IS_ERR(folio))
                return PTR_ERR(folio);
        /*
         * The mapped position should be within the current processing folio
         * but must not be the folio start position.
         */
        pos = ((loff_t)mpd->map.m_lblk) << inode->i_blkbits;
        if (WARN_ON_ONCE((folio_pos(folio) == pos) ||
                         !folio_contains(folio, pos >> PAGE_SHIFT)))
                return -EINVAL;

        ret = mpage_submit_folio(mpd, folio);
        if (ret)
                goto out;
        /*
         * Update start_pos to prevent this folio from being released in
         * mpage_release_unused_pages(), it will be reset to the aligned folio
         * pos when this folio is written again in the next round. Additionally,
         * do not update wbc->nr_to_write here, as it will be updated once the
         * entire folio has finished processing.
         */
        mpd->start_pos = pos;
out:
        folio_unlock(folio);
        folio_put(folio);
        return ret;
}

/*
 * mpage_map_and_submit_extent - map extent starting at mpd->lblk of length
 *                               mpd->len and submit pages underlying it for IO
 *
 * @handle - handle for journal operations
 * @mpd - extent to map
 * @give_up_on_write - we set this to true iff there is a fatal error and there
 *                     is no hope of writing the data. The caller should discard
 *                     dirty pages to avoid infinite loops.
 *
 * The function maps extent starting at mpd->lblk of length mpd->len. If it is
 * delayed, blocks are allocated, if it is unwritten, we may need to convert
 * them to initialized or split the described range from larger unwritten
 * extent. Note that we need not map all the described range since allocation
 * can return less blocks or the range is covered by more unwritten extents. We
 * cannot map more because we are limited by reserved transaction credits. On
 * the other hand we always make sure that the last touched page is fully
 * mapped so that it can be written out (and thus forward progress is
 * guaranteed). After mapping we submit all mapped pages for IO.
 */
static int mpage_map_and_submit_extent(handle_t *handle,
                                       struct mpage_da_data *mpd,
                                       bool *give_up_on_write)
{
        struct inode *inode = mpd->inode;
        struct ext4_map_blocks *map = &mpd->map;
        int err;
        loff_t disksize;
        int progress = 0;
        ext4_io_end_t *io_end = mpd->io_submit.io_end;
        struct ext4_io_end_vec *io_end_vec;

        io_end_vec = ext4_alloc_io_end_vec(io_end);
        if (IS_ERR(io_end_vec))
                return PTR_ERR(io_end_vec);
        io_end_vec->offset = EXT4_LBLK_TO_B(inode, map->m_lblk);
        do {
                err = mpage_map_one_extent(handle, mpd);
                if (err < 0) {
                        struct super_block *sb = inode->i_sb;

                        if (ext4_emergency_state(sb))
                                goto invalidate_dirty_pages;
                        /*
                         * Let the uper layers retry transient errors.
                         * In the case of ENOSPC, if ext4_count_free_blocks()
                         * is non-zero, a commit should free up blocks.
                         */
                        if ((err == -ENOMEM) || (err == -EAGAIN) ||
                            (err == -ENOSPC && ext4_count_free_clusters(sb))) {
                                /*
                                 * We may have already allocated extents for
                                 * some bhs inside the folio, issue the
                                 * corresponding data to prevent stale data.
                                 */
                                if (progress) {
                                        if (mpage_submit_partial_folio(mpd))
                                                goto invalidate_dirty_pages;
                                        goto update_disksize;
                                }
                                return err;
                        }
                        ext4_msg(sb, KERN_CRIT,
                                 "Delayed block allocation failed for "
                                 "inode %lu at logical offset %llu with"
                                 " max blocks %u with error %d",
                                 inode->i_ino,
                                 (unsigned long long)map->m_lblk,
                                 (unsigned)map->m_len, -err);
                        ext4_msg(sb, KERN_CRIT,
                                 "This should not happen!! Data will "
                                 "be lost\n");
                        if (err == -ENOSPC)
                                ext4_print_free_blocks(inode);
                invalidate_dirty_pages:
                        *give_up_on_write = true;
                        return err;
                }
                progress = 1;
                /*
                 * Update buffer state, submit mapped pages, and get us new
                 * extent to map
                 */
                err = mpage_map_and_submit_buffers(mpd);
                if (err < 0)
                        goto update_disksize;
        } while (map->m_len);

update_disksize:
        /*
         * Update on-disk size after IO is submitted.  Races with
         * truncate are avoided by checking i_size under i_data_sem.
         */
        disksize = mpd->start_pos;
        if (disksize > READ_ONCE(EXT4_I(inode)->i_disksize)) {
                int err2;
                loff_t i_size;

                down_write(&EXT4_I(inode)->i_data_sem);
                i_size = i_size_read(inode);
                if (disksize > i_size)
                        disksize = i_size;
                if (disksize > EXT4_I(inode)->i_disksize)
                        EXT4_I(inode)->i_disksize = disksize;
                up_write(&EXT4_I(inode)->i_data_sem);
                err2 = ext4_mark_inode_dirty(handle, inode);
                if (err2) {
                        ext4_error_err(inode->i_sb, -err2,
                                       "Failed to mark inode %lu dirty",
                                       inode->i_ino);
                }
                if (!err)
                        err = err2;
        }
        return err;
}

static int ext4_journal_folio_buffers(handle_t *handle, struct folio *folio,
                                     size_t len)
{
        struct buffer_head *page_bufs = folio_buffers(folio);
        struct inode *inode = folio->mapping->host;
        int ret, err;

        ret = ext4_walk_page_buffers(handle, inode, page_bufs, 0, len,
                                     NULL, do_journal_get_write_access);
        err = ext4_walk_page_buffers(handle, inode, page_bufs, 0, len,
                                     NULL, write_end_fn);
        if (ret == 0)
                ret = err;
        err = ext4_jbd2_inode_add_write(handle, inode, folio_pos(folio), len);
        if (ret == 0)
                ret = err;
        EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;

        return ret;
}

static int mpage_journal_page_buffers(handle_t *handle,
                                      struct mpage_da_data *mpd,
                                      struct folio *folio)
{
        struct inode *inode = mpd->inode;
        loff_t size = i_size_read(inode);
        size_t len = folio_size(folio);

        folio_clear_checked(folio);
        mpd->wbc->nr_to_write -= folio_nr_pages(folio);

        if (folio_pos(folio) + len > size &&
            !ext4_verity_in_progress(inode))
                len = size & (len - 1);

        return ext4_journal_folio_buffers(handle, folio, len);
}

/*
 * mpage_prepare_extent_to_map - find & lock contiguous range of dirty pages
 *                               needing mapping, submit mapped pages
 *
 * @mpd - where to look for pages
 *
 * Walk dirty pages in the mapping. If they are fully mapped, submit them for
 * IO immediately. If we cannot map blocks, we submit just already mapped
 * buffers in the page for IO and keep page dirty. When we can map blocks and
 * we find a page which isn't mapped we start accumulating extent of buffers
 * underlying these pages that needs mapping (formed by either delayed or
 * unwritten buffers). We also lock the pages containing these buffers. The
 * extent found is returned in @mpd structure (starting at mpd->lblk with
 * length mpd->len blocks).
 *
 * Note that this function can attach bios to one io_end structure which are
 * neither logically nor physically contiguous. Although it may seem as an
 * unnecessary complication, it is actually inevitable in blocksize < pagesize
 * case as we need to track IO to all buffers underlying a page in one io_end.
 */
static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd)
{
        struct address_space *mapping = mpd->inode->i_mapping;
        struct folio_batch fbatch;
        unsigned int nr_folios;
        pgoff_t index = mpd->start_pos >> PAGE_SHIFT;
        pgoff_t end = mpd->end_pos >> PAGE_SHIFT;
        xa_mark_t tag;
        int i, err = 0;
        ext4_lblk_t lblk;
        struct buffer_head *head;
        handle_t *handle = NULL;
        int bpp = ext4_journal_blocks_per_folio(mpd->inode);

        tag = wbc_to_tag(mpd->wbc);

        mpd->map.m_len = 0;
        mpd->next_pos = mpd->start_pos;
        if (ext4_should_journal_data(mpd->inode)) {
                handle = ext4_journal_start(mpd->inode, EXT4_HT_WRITE_PAGE,
                                            bpp);
                if (IS_ERR(handle))
                        return PTR_ERR(handle);
        }
        folio_batch_init(&fbatch);
        while (index <= end) {
                nr_folios = filemap_get_folios_tag(mapping, &index, end,
                                tag, &fbatch);
                if (nr_folios == 0)
                        break;

                for (i = 0; i < nr_folios; i++) {
                        struct folio *folio = fbatch.folios[i];

                        /*
                         * Accumulated enough dirty pages? This doesn't apply
                         * to WB_SYNC_ALL mode. For integrity sync we have to
                         * keep going because someone may be concurrently
                         * dirtying pages, and we might have synced a lot of
                         * newly appeared dirty pages, but have not synced all
                         * of the old dirty pages.
                         */
                        if (mpd->wbc->sync_mode == WB_SYNC_NONE &&
                            mpd->wbc->nr_to_write <=
                            EXT4_LBLK_TO_PG(mpd->inode, mpd->map.m_len))
                                goto out;

                        /* If we can't merge this page, we are done. */
                        if (mpd->map.m_len > 0 &&
                            mpd->next_pos != folio_pos(folio))
                                goto out;

                        if (handle) {
                                err = ext4_journal_ensure_credits(handle, bpp,
                                                                  0);
                                if (err < 0)
                                        goto out;
                        }

                        folio_lock(folio);
                        /*
                         * If the page is no longer dirty, or its mapping no
                         * longer corresponds to inode we are writing (which
                         * means it has been truncated or invalidated), or the
                         * page is already under writeback and we are not doing
                         * a data integrity writeback, skip the page
                         */
                        if (!folio_test_dirty(folio) ||
                            (folio_test_writeback(folio) &&
                             (mpd->wbc->sync_mode == WB_SYNC_NONE)) ||
                            unlikely(folio->mapping != mapping)) {
                                folio_unlock(folio);
                                continue;
                        }

                        folio_wait_writeback(folio);
                        BUG_ON(folio_test_writeback(folio));

                        /*
                         * Should never happen but for buggy code in
                         * other subsystems that call
                         * set_page_dirty() without properly warning
                         * the file system first.  See [1] for more
                         * information.
                         *
                         * [1] https://lore.kernel.org/linux-mm/20180103100430.GE4911@quack2.suse.cz
                         */
                        if (!folio_buffers(folio)) {
                                ext4_warning_inode(mpd->inode, "page %lu does not have buffers attached", folio->index);
                                folio_clear_dirty(folio);
                                folio_unlock(folio);
                                continue;
                        }

                        if (mpd->map.m_len == 0)
                                mpd->start_pos = folio_pos(folio);
                        mpd->next_pos = folio_next_pos(folio);
                        /*
                         * Writeout when we cannot modify metadata is simple.
                         * Just submit the page. For data=journal mode we
                         * first handle writeout of the page for checkpoint and
                         * only after that handle delayed page dirtying. This
                         * makes sure current data is checkpointed to the final
                         * location before possibly journalling it again which
                         * is desirable when the page is frequently dirtied
                         * through a pin.
                         */
                        if (!mpd->can_map) {
                                err = mpage_submit_folio(mpd, folio);
                                if (err < 0)
                                        goto out;
                                /* Pending dirtying of journalled data? */
                                if (folio_test_checked(folio)) {
                                        err = mpage_journal_page_buffers(handle,
                                                mpd, folio);
                                        if (err < 0)
                                                goto out;
                                        mpd->journalled_more_data = 1;
                                }
                                mpage_folio_done(mpd, folio);
                        } else {
                                /* Add all dirty buffers to mpd */
                                lblk = EXT4_PG_TO_LBLK(mpd->inode, folio->index);
                                head = folio_buffers(folio);
                                err = mpage_process_page_bufs(mpd, head, head,
                                                lblk);
                                if (err <= 0)
                                        goto out;
                                err = 0;
                        }
                }
                folio_batch_release(&fbatch);
                cond_resched();
        }
        mpd->scanned_until_end = 1;
        if (handle)
                ext4_journal_stop(handle);
        return 0;
out:
        folio_batch_release(&fbatch);
        if (handle)
                ext4_journal_stop(handle);
        return err;
}

static int ext4_do_writepages(struct mpage_da_data *mpd)
{
        struct writeback_control *wbc = mpd->wbc;
        pgoff_t writeback_index = 0;
        long nr_to_write = wbc->nr_to_write;
        int range_whole = 0;
        int cycled = 1;
        handle_t *handle = NULL;
        struct inode *inode = mpd->inode;
        struct address_space *mapping = inode->i_mapping;
        int needed_blocks, rsv_blocks = 0, ret = 0;
        struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
        struct blk_plug plug;
        bool give_up_on_write = false;

        trace_ext4_writepages(inode, wbc);

        /*
         * No pages to write? This is mainly a kludge to avoid starting
         * a transaction for special inodes like journal inode on last iput()
         * because that could violate lock ordering on umount
         */
        if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
                goto out_writepages;

        /*
         * If the filesystem has aborted, it is read-only, so return
         * right away instead of dumping stack traces later on that
         * will obscure the real source of the problem.  We test
         * fs shutdown state instead of sb->s_flag's SB_RDONLY because
         * the latter could be true if the filesystem is mounted
         * read-only, and in that case, ext4_writepages should
         * *never* be called, so if that ever happens, we would want
         * the stack trace.
         */
        ret = ext4_emergency_state(mapping->host->i_sb);
        if (unlikely(ret))
                goto out_writepages;

        /*
         * If we have inline data and arrive here, it means that
         * we will soon create the block for the 1st page, so
         * we'd better clear the inline data here.
         */
        if (ext4_has_inline_data(inode)) {
                /* Just inode will be modified... */
                handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
                if (IS_ERR(handle)) {
                        ret = PTR_ERR(handle);
                        goto out_writepages;
                }
                BUG_ON(ext4_test_inode_state(inode,
                                EXT4_STATE_MAY_INLINE_DATA));
                ext4_destroy_inline_data(handle, inode);
                ext4_journal_stop(handle);
        }

        /*
         * data=journal mode does not do delalloc so we just need to writeout /
         * journal already mapped buffers. On the other hand we need to commit
         * transaction to make data stable. We expect all the data to be
         * already in the journal (the only exception are DMA pinned pages
         * dirtied behind our back) so we commit transaction here and run the
         * writeback loop to checkpoint them. The checkpointing is not actually
         * necessary to make data persistent *but* quite a few places (extent
         * shifting operations, fsverity, ...) depend on being able to drop
         * pagecache pages after calling filemap_write_and_wait() and for that
         * checkpointing needs to happen.
         */
        if (ext4_should_journal_data(inode)) {
                mpd->can_map = 0;
                if (wbc->sync_mode == WB_SYNC_ALL)
                        ext4_fc_commit(sbi->s_journal,
                                       EXT4_I(inode)->i_datasync_tid);
        }
        mpd->journalled_more_data = 0;

        if (ext4_should_dioread_nolock(inode)) {
                int bpf = ext4_journal_blocks_per_folio(inode);
                /*
                 * We may need to convert up to one extent per block in
                 * the folio and we may dirty the inode.
                 */
                rsv_blocks = 1 + ext4_ext_index_trans_blocks(inode, bpf);
        }

        if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
                range_whole = 1;

        if (wbc->range_cyclic) {
                writeback_index = mapping->writeback_index;
                if (writeback_index)
                        cycled = 0;
                mpd->start_pos = writeback_index << PAGE_SHIFT;
                mpd->end_pos = LLONG_MAX;
        } else {
                mpd->start_pos = wbc->range_start;
                mpd->end_pos = wbc->range_end;
        }

        ext4_io_submit_init(&mpd->io_submit, wbc);
retry:
        if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
                tag_pages_for_writeback(mapping, mpd->start_pos >> PAGE_SHIFT,
                                        mpd->end_pos >> PAGE_SHIFT);
        blk_start_plug(&plug);

        /*
         * First writeback pages that don't need mapping - we can avoid
         * starting a transaction unnecessarily and also avoid being blocked
         * in the block layer on device congestion while having transaction
         * started.
         */
        mpd->do_map = 0;
        mpd->scanned_until_end = 0;
        mpd->io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
        if (!mpd->io_submit.io_end) {
                ret = -ENOMEM;
                goto unplug;
        }
        ret = mpage_prepare_extent_to_map(mpd);
        /* Unlock pages we didn't use */
        mpage_release_unused_pages(mpd, false);
        /* Submit prepared bio */
        ext4_io_submit(&mpd->io_submit);
        ext4_put_io_end_defer(mpd->io_submit.io_end);
        mpd->io_submit.io_end = NULL;
        if (ret < 0)
                goto unplug;

        while (!mpd->scanned_until_end && wbc->nr_to_write > 0) {
                /* For each extent of pages we use new io_end */
                mpd->io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
                if (!mpd->io_submit.io_end) {
                        ret = -ENOMEM;
                        break;
                }

                WARN_ON_ONCE(!mpd->can_map);
                /*
                 * We have two constraints: We find one extent to map and we
                 * must always write out whole page (makes a difference when
                 * blocksize < pagesize) so that we don't block on IO when we
                 * try to write out the rest of the page. Journalled mode is
                 * not supported by delalloc.
                 */
                BUG_ON(ext4_should_journal_data(inode));
                /*
                 * Calculate the number of credits needed to reserve for one
                 * extent of up to MAX_WRITEPAGES_EXTENT_LEN blocks. It will
                 * attempt to extend the transaction or start a new iteration
                 * if the reserved credits are insufficient.
                 */
                needed_blocks = ext4_chunk_trans_blocks(inode,
                                                MAX_WRITEPAGES_EXTENT_LEN);
                /* start a new transaction */
                handle = ext4_journal_start_with_reserve(inode,
                                EXT4_HT_WRITE_PAGE, needed_blocks, rsv_blocks);
                if (IS_ERR(handle)) {
                        ret = PTR_ERR(handle);
                        ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
                               "%ld pages, ino %lu; err %d", __func__,
                                wbc->nr_to_write, inode->i_ino, ret);
                        /* Release allocated io_end */
                        ext4_put_io_end(mpd->io_submit.io_end);
                        mpd->io_submit.io_end = NULL;
                        break;
                }
                mpd->do_map = 1;

                trace_ext4_da_write_folios_start(inode, mpd->start_pos,
                                mpd->next_pos, wbc);
                ret = mpage_prepare_extent_to_map(mpd);
                if (!ret && mpd->map.m_len)
                        ret = mpage_map_and_submit_extent(handle, mpd,
                                        &give_up_on_write);
                /*
                 * Caution: If the handle is synchronous,
                 * ext4_journal_stop() can wait for transaction commit
                 * to finish which may depend on writeback of pages to
                 * complete or on page lock to be released.  In that
                 * case, we have to wait until after we have
                 * submitted all the IO, released page locks we hold,
                 * and dropped io_end reference (for extent conversion
                 * to be able to complete) before stopping the handle.
                 */
                if (!ext4_handle_valid(handle) || handle->h_sync == 0) {
                        ext4_journal_stop(handle);
                        handle = NULL;
                        mpd->do_map = 0;
                }
                /* Unlock pages we didn't use */
                mpage_release_unused_pages(mpd, give_up_on_write);
                /* Submit prepared bio */
                ext4_io_submit(&mpd->io_submit);

                /*
                 * Drop our io_end reference we got from init. We have
                 * to be careful and use deferred io_end finishing if
                 * we are still holding the transaction as we can
                 * release the last reference to io_end which may end
                 * up doing unwritten extent conversion.
                 */
                if (handle) {
                        ext4_put_io_end_defer(mpd->io_submit.io_end);
                        ext4_journal_stop(handle);
                } else
                        ext4_put_io_end(mpd->io_submit.io_end);
                mpd->io_submit.io_end = NULL;
                trace_ext4_da_write_folios_end(inode, mpd->start_pos,
                                mpd->next_pos, wbc, ret);

                if (ret == -ENOSPC && sbi->s_journal) {
                        /*
                         * Commit the transaction which would
                         * free blocks released in the transaction
                         * and try again
                         */
                        jbd2_journal_force_commit_nested(sbi->s_journal);
                        ret = 0;
                        continue;
                }
                if (ret == -EAGAIN)
                        ret = 0;
                /* Fatal error - ENOMEM, EIO... */
                if (ret)
                        break;
        }
unplug:
        blk_finish_plug(&plug);
        if (!ret && !cycled && wbc->nr_to_write > 0) {
                cycled = 1;
                mpd->end_pos = (writeback_index << PAGE_SHIFT) - 1;
                mpd->start_pos = 0;
                goto retry;
        }

        /* Update index */
        if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
                /*
                 * Set the writeback_index so that range_cyclic
                 * mode will write it back later
                 */
                mapping->writeback_index = mpd->start_pos >> PAGE_SHIFT;

out_writepages:
        trace_ext4_writepages_result(inode, wbc, ret,
                                     nr_to_write - wbc->nr_to_write);
        return ret;
}

static int ext4_writepages(struct address_space *mapping,
                           struct writeback_control *wbc)
{
        struct super_block *sb = mapping->host->i_sb;
        struct mpage_da_data mpd = {
                .inode = mapping->host,
                .wbc = wbc,
                .can_map = 1,
        };
        int ret;
        int alloc_ctx;

        ret = ext4_emergency_state(sb);
        if (unlikely(ret))
                return ret;

        alloc_ctx = ext4_writepages_down_read(sb);
        ret = ext4_do_writepages(&mpd);
        /*
         * For data=journal writeback we could have come across pages marked
         * for delayed dirtying (PageChecked) which were just added to the
         * running transaction. Try once more to get them to stable storage.
         */
        if (!ret && mpd.journalled_more_data)
                ret = ext4_do_writepages(&mpd);
        ext4_writepages_up_read(sb, alloc_ctx);

        return ret;
}

int ext4_normal_submit_inode_data_buffers(struct jbd2_inode *jinode)
{
        struct writeback_control wbc = {
                .sync_mode = WB_SYNC_ALL,
                .nr_to_write = LONG_MAX,
                .range_start = jinode->i_dirty_start,
                .range_end = jinode->i_dirty_end,
        };
        struct mpage_da_data mpd = {
                .inode = jinode->i_vfs_inode,
                .wbc = &wbc,
                .can_map = 0,
        };
        return ext4_do_writepages(&mpd);
}

static int ext4_dax_writepages(struct address_space *mapping,
                               struct writeback_control *wbc)
{
        int ret;
        long nr_to_write = wbc->nr_to_write;
        struct inode *inode = mapping->host;
        int alloc_ctx;

        ret = ext4_emergency_state(inode->i_sb);
        if (unlikely(ret))
                return ret;

        alloc_ctx = ext4_writepages_down_read(inode->i_sb);
        trace_ext4_writepages(inode, wbc);

        ret = dax_writeback_mapping_range(mapping,
                                          EXT4_SB(inode->i_sb)->s_daxdev, wbc);
        trace_ext4_writepages_result(inode, wbc, ret,
                                     nr_to_write - wbc->nr_to_write);
        ext4_writepages_up_read(inode->i_sb, alloc_ctx);
        return ret;
}

static int ext4_nonda_switch(struct super_block *sb)
{
        s64 free_clusters, dirty_clusters;
        struct ext4_sb_info *sbi = EXT4_SB(sb);

        /*
         * switch to non delalloc mode if we are running low
         * on free block. The free block accounting via percpu
         * counters can get slightly wrong with percpu_counter_batch getting
         * accumulated on each CPU without updating global counters
         * Delalloc need an accurate free block accounting. So switch
         * to non delalloc when we are near to error range.
         */
        free_clusters =
                percpu_counter_read_positive(&sbi->s_freeclusters_counter);
        dirty_clusters =
                percpu_counter_read_positive(&sbi->s_dirtyclusters_counter);
        /*
         * Start pushing delalloc when 1/2 of free blocks are dirty.
         */
        if (dirty_clusters && (free_clusters < 2 * dirty_clusters))
                try_to_writeback_inodes_sb(sb, WB_REASON_FS_FREE_SPACE);

        if (2 * free_clusters < 3 * dirty_clusters ||
            free_clusters < (dirty_clusters + EXT4_FREECLUSTERS_WATERMARK)) {
                /*
                 * free block count is less than 150% of dirty blocks
                 * or free blocks is less than watermark
                 */
                return 1;
        }
        return 0;
}

static int ext4_da_write_begin(const struct kiocb *iocb,
                               struct address_space *mapping,
                               loff_t pos, unsigned len,
                               struct folio **foliop, void **fsdata)
{
        int ret, retries = 0;
        struct folio *folio;
        pgoff_t index;
        struct inode *inode = mapping->host;

        ret = ext4_emergency_state(inode->i_sb);
        if (unlikely(ret))
                return ret;

        index = pos >> PAGE_SHIFT;

        if (ext4_nonda_switch(inode->i_sb) || ext4_verity_in_progress(inode)) {
                *fsdata = (void *)FALL_BACK_TO_NONDELALLOC;
                return ext4_write_begin(iocb, mapping, pos,
                                        len, foliop, fsdata);
        }
        *fsdata = (void *)0;
        trace_ext4_da_write_begin(inode, pos, len);

        if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
                ret = ext4_generic_write_inline_data(mapping, inode, pos, len,
                                                     foliop, fsdata, true);
                if (ret < 0)
                        return ret;
                if (ret == 1)
                        return 0;
        }

retry:
        folio = write_begin_get_folio(iocb, mapping, index, len);
        if (IS_ERR(folio))
                return PTR_ERR(folio);

        if (len > folio_next_pos(folio) - pos)
                len = folio_next_pos(folio) - pos;

        ret = ext4_block_write_begin(NULL, folio, pos, len,
                                     ext4_da_get_block_prep);
        if (ret < 0) {
                folio_unlock(folio);
                folio_put(folio);
                /*
                 * ext4_block_write_begin may have instantiated a few blocks
                 * outside i_size.  Trim these off again. Don't need
                 * i_size_read because we hold inode lock.
                 */
                if (pos + len > inode->i_size)
                        ext4_truncate_failed_write(inode);

                if (ret == -ENOSPC &&
                    ext4_should_retry_alloc(inode->i_sb, &retries))
                        goto retry;
                return ret;
        }

        *foliop = folio;
        return ret;
}

/*
 * Check if we should update i_disksize
 * when write to the end of file but not require block allocation
 */
static int ext4_da_should_update_i_disksize(struct folio *folio,
                                            unsigned long offset)
{
        struct buffer_head *bh;
        struct inode *inode = folio->mapping->host;
        unsigned int idx;
        int i;

        bh = folio_buffers(folio);
        idx = offset >> inode->i_blkbits;

        for (i = 0; i < idx; i++)
                bh = bh->b_this_page;

        if (!buffer_mapped(bh) || (buffer_delay(bh)) || buffer_unwritten(bh))
                return 0;
        return 1;
}

static int ext4_da_do_write_end(struct address_space *mapping,
                        loff_t pos, unsigned len, unsigned copied,
                        struct folio *folio)
{
        struct inode *inode = mapping->host;
        loff_t old_size = inode->i_size;
        bool disksize_changed = false;
        loff_t new_i_size, zero_len = 0;
        handle_t *handle;

        if (unlikely(!folio_buffers(folio))) {
                folio_unlock(folio);
                folio_put(folio);
                return -EIO;
        }
        /*
         * block_write_end() will mark the inode as dirty with I_DIRTY_PAGES
         * flag, which all that's needed to trigger page writeback.
         */
        copied = block_write_end(pos, len, copied, folio);
        new_i_size = pos + copied;

        /*
         * It's important to update i_size while still holding folio lock,
         * because folio writeout could otherwise come in and zero beyond
         * i_size.
         *
         * Since we are holding inode lock, we are sure i_disksize <=
         * i_size. We also know that if i_disksize < i_size, there are
         * delalloc writes pending in the range up to i_size. If the end of
         * the current write is <= i_size, there's no need to touch
         * i_disksize since writeback will push i_disksize up to i_size
         * eventually. If the end of the current write is > i_size and
         * inside an allocated block which ext4_da_should_update_i_disksize()
         * checked, we need to update i_disksize here as certain
         * ext4_writepages() paths not allocating blocks and update i_disksize.
         */
        if (new_i_size > inode->i_size) {
                unsigned long end;

                i_size_write(inode, new_i_size);
                end = offset_in_folio(folio, new_i_size - 1);
                if (copied && ext4_da_should_update_i_disksize(folio, end)) {
                        ext4_update_i_disksize(inode, new_i_size);
                        disksize_changed = true;
                }
        }

        folio_unlock(folio);
        folio_put(folio);

        if (pos > old_size) {
                pagecache_isize_extended(inode, old_size, pos);
                zero_len = pos - old_size;
        }

        if (!disksize_changed && !zero_len)
                return copied;

        handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
        if (IS_ERR(handle))
                return PTR_ERR(handle);
        if (zero_len)
                ext4_zero_partial_blocks(handle, inode, old_size, zero_len);
        ext4_mark_inode_dirty(handle, inode);
        ext4_journal_stop(handle);

        return copied;
}

static int ext4_da_write_end(const struct kiocb *iocb,
                             struct address_space *mapping,
                             loff_t pos, unsigned len, unsigned copied,
                             struct folio *folio, void *fsdata)
{
        struct inode *inode = mapping->host;
        int write_mode = (int)(unsigned long)fsdata;

        if (write_mode == FALL_BACK_TO_NONDELALLOC)
                return ext4_write_end(iocb, mapping, pos,
                                      len, copied, folio, fsdata);

        trace_ext4_da_write_end(inode, pos, len, copied);

        if (write_mode != CONVERT_INLINE_DATA &&
            ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) &&
            ext4_has_inline_data(inode))
                return ext4_write_inline_data_end(inode, pos, len, copied,
                                                  folio);

        if (unlikely(copied < len) && !folio_test_uptodate(folio))
                copied = 0;

        return ext4_da_do_write_end(mapping, pos, len, copied, folio);
}

/*
 * Force all delayed allocation blocks to be allocated for a given inode.
 */
int ext4_alloc_da_blocks(struct inode *inode)
{
        trace_ext4_alloc_da_blocks(inode);

        if (!EXT4_I(inode)->i_reserved_data_blocks)
                return 0;

        /*
         * We do something simple for now.  The filemap_flush() will
         * also start triggering a write of the data blocks, which is
         * not strictly speaking necessary.  However, to do otherwise
         * would require replicating code paths in:
         *
         * ext4_writepages() ->
         *    write_cache_pages() ---> (via passed in callback function)
         *        __mpage_da_writepage() -->
         *           mpage_add_bh_to_extent()
         *           mpage_da_map_blocks()
         *
         * The problem is that write_cache_pages(), located in
         * mm/page-writeback.c, marks pages clean in preparation for
         * doing I/O, which is not desirable if we're not planning on
         * doing I/O at all.
         *
         * We could call write_cache_pages(), and then redirty all of
         * the pages by calling redirty_page_for_writepage() but that
         * would be ugly in the extreme.  So instead we would need to
         * replicate parts of the code in the above functions,
         * simplifying them because we wouldn't actually intend to
         * write out the pages, but rather only collect contiguous
         * logical block extents, call the multi-block allocator, and
         * then update the buffer heads with the block allocations.
         *
         * For now, though, we'll cheat by calling filemap_flush(),
         * which will map the blocks, and start the I/O, but not
         * actually wait for the I/O to complete.
         */
        return filemap_flush(inode->i_mapping);
}

/*
 * bmap() is special.  It gets used by applications such as lilo and by
 * the swapper to find the on-disk block of a specific piece of data.
 *
 * Naturally, this is dangerous if the block concerned is still in the
 * journal.  If somebody makes a swapfile on an ext4 data-journaling
 * filesystem and enables swap, then they may get a nasty shock when the
 * data getting swapped to that swapfile suddenly gets overwritten by
 * the original zero's written out previously to the journal and
 * awaiting writeback in the kernel's buffer cache.
 *
 * So, if we see any bmap calls here on a modified, data-journaled file,
 * take extra steps to flush any blocks which might be in the cache.
 */
static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
{
        struct inode *inode = mapping->host;
        sector_t ret = 0;

        inode_lock_shared(inode);
        /*
         * We can get here for an inline file via the FIBMAP ioctl
         */
        if (ext4_has_inline_data(inode))
                goto out;

        if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
            (test_opt(inode->i_sb, DELALLOC) ||
             ext4_should_journal_data(inode))) {
                /*
                 * With delalloc or journalled data we want to sync the file so
                 * that we can make sure we allocate blocks for file and data
                 * is in place for the user to see it
                 */
                filemap_write_and_wait(mapping);
        }

        ret = iomap_bmap(mapping, block, &ext4_iomap_ops);

out:
        inode_unlock_shared(inode);
        return ret;
}

static void ext4_invalidate_folio(struct folio *folio, size_t offset,
                                size_t length)
{
        trace_ext4_invalidate_folio(folio, offset, length);

        /* No journalling happens on data buffers when this function is used */
        WARN_ON(folio_buffers(folio) && buffer_jbd(folio_buffers(folio)));

        block_invalidate_folio(folio, offset, length);
}

static int __ext4_journalled_invalidate_folio(struct folio *folio,
                                            size_t offset, size_t length)
{
        journal_t *journal = EXT4_JOURNAL(folio->mapping->host);

        trace_ext4_journalled_invalidate_folio(folio, offset, length);

        /*
         * If it's a full truncate we just forget about the pending dirtying
         */
        if (offset == 0 && length == folio_size(folio))
                folio_clear_checked(folio);

        return jbd2_journal_invalidate_folio(journal, folio, offset, length);
}

/* Wrapper for aops... */
static void ext4_journalled_invalidate_folio(struct folio *folio,
                                           size_t offset,
                                           size_t length)
{
        WARN_ON(__ext4_journalled_invalidate_folio(folio, offset, length) < 0);
}

static bool ext4_release_folio(struct folio *folio, gfp_t wait)
{
        struct inode *inode = folio->mapping->host;
        journal_t *journal = EXT4_JOURNAL(inode);

        trace_ext4_release_folio(inode, folio);

        /* Page has dirty journalled data -> cannot release */
        if (folio_test_checked(folio))
                return false;
        if (journal)
                return jbd2_journal_try_to_free_buffers(journal, folio);
        else
                return try_to_free_buffers(folio);
}

static bool ext4_inode_datasync_dirty(struct inode *inode)
{
        journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;

        if (journal) {
                if (jbd2_transaction_committed(journal,
                        EXT4_I(inode)->i_datasync_tid))
                        return false;
                if (test_opt2(inode->i_sb, JOURNAL_FAST_COMMIT))
                        return !list_empty(&EXT4_I(inode)->i_fc_list);
                return true;
        }

        /* Any metadata buffers to write? */
        if (!list_empty(&inode->i_mapping->i_private_list))
                return true;
        return inode_state_read_once(inode) & I_DIRTY_DATASYNC;
}

static void ext4_set_iomap(struct inode *inode, struct iomap *iomap,
                           struct ext4_map_blocks *map, loff_t offset,
                           loff_t length, unsigned int flags)
{
        u8 blkbits = inode->i_blkbits;

        /*
         * Writes that span EOF might trigger an I/O size update on completion,
         * so consider them to be dirty for the purpose of O_DSYNC, even if
         * there is no other metadata changes being made or are pending.
         */
        iomap->flags = 0;
        if (ext4_inode_datasync_dirty(inode) ||
            offset + length > i_size_read(inode))
                iomap->flags |= IOMAP_F_DIRTY;

        if (map->m_flags & EXT4_MAP_NEW)
                iomap->flags |= IOMAP_F_NEW;

        /* HW-offload atomics are always used */
        if (flags & IOMAP_ATOMIC)
                iomap->flags |= IOMAP_F_ATOMIC_BIO;

        if (flags & IOMAP_DAX)
                iomap->dax_dev = EXT4_SB(inode->i_sb)->s_daxdev;
        else
                iomap->bdev = inode->i_sb->s_bdev;
        iomap->offset = EXT4_LBLK_TO_B(inode, map->m_lblk);
        iomap->length = EXT4_LBLK_TO_B(inode, map->m_len);

        if ((map->m_flags & EXT4_MAP_MAPPED) &&
            !ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
                iomap->flags |= IOMAP_F_MERGED;

        /*
         * Flags passed to ext4_map_blocks() for direct I/O writes can result
         * in m_flags having both EXT4_MAP_MAPPED and EXT4_MAP_UNWRITTEN bits
         * set. In order for any allocated unwritten extents to be converted
         * into written extents correctly within the ->end_io() handler, we
         * need to ensure that the iomap->type is set appropriately. Hence, the
         * reason why we need to check whether the EXT4_MAP_UNWRITTEN bit has
         * been set first.
         */
        if (map->m_flags & EXT4_MAP_UNWRITTEN) {
                iomap->type = IOMAP_UNWRITTEN;
                iomap->addr = (u64) map->m_pblk << blkbits;
                if (flags & IOMAP_DAX)
                        iomap->addr += EXT4_SB(inode->i_sb)->s_dax_part_off;
        } else if (map->m_flags & EXT4_MAP_MAPPED) {
                iomap->type = IOMAP_MAPPED;
                iomap->addr = (u64) map->m_pblk << blkbits;
                if (flags & IOMAP_DAX)
                        iomap->addr += EXT4_SB(inode->i_sb)->s_dax_part_off;
        } else if (map->m_flags & EXT4_MAP_DELAYED) {
                iomap->type = IOMAP_DELALLOC;
                iomap->addr = IOMAP_NULL_ADDR;
        } else {
                iomap->type = IOMAP_HOLE;
                iomap->addr = IOMAP_NULL_ADDR;
        }
}

static int ext4_map_blocks_atomic_write_slow(handle_t *handle,
                        struct inode *inode, struct ext4_map_blocks *map)
{
        ext4_lblk_t m_lblk = map->m_lblk;
        unsigned int m_len = map->m_len;
        unsigned int mapped_len = 0, m_flags = 0;
        ext4_fsblk_t next_pblk = 0;
        bool check_next_pblk = false;
        int ret = 0;

        WARN_ON_ONCE(!ext4_has_feature_bigalloc(inode->i_sb));

        /*
         * This is a slow path in case of mixed mapping. We use
         * EXT4_GET_BLOCKS_CREATE_ZERO flag here to make sure we get a single
         * contiguous mapped mapping. This will ensure any unwritten or hole
         * regions within the requested range is zeroed out and we return
         * a single contiguous mapped extent.
         */
        m_flags = EXT4_GET_BLOCKS_CREATE_ZERO;

        do {
                ret = ext4_map_blocks(handle, inode, map, m_flags);
                if (ret < 0 && ret != -ENOSPC)
                        goto out_err;
                /*
                 * This should never happen, but let's return an error code to
                 * avoid an infinite loop in here.
                 */
                if (ret == 0) {
                        ret = -EFSCORRUPTED;
                        ext4_warning_inode(inode,
                                "ext4_map_blocks() couldn't allocate blocks m_flags: 0x%x, ret:%d",
                                m_flags, ret);
                        goto out_err;
                }
                /*
                 * With bigalloc we should never get ENOSPC nor discontiguous
                 * physical extents.
                 */
                if ((check_next_pblk && next_pblk != map->m_pblk) ||
                                ret == -ENOSPC) {
                        ext4_warning_inode(inode,
                                "Non-contiguous allocation detected: expected %llu, got %llu, "
                                "or ext4_map_blocks() returned out of space ret: %d",
                                next_pblk, map->m_pblk, ret);
                        ret = -EFSCORRUPTED;
                        goto out_err;
                }
                next_pblk = map->m_pblk + map->m_len;
                check_next_pblk = true;

                mapped_len += map->m_len;
                map->m_lblk += map->m_len;
                map->m_len = m_len - mapped_len;
        } while (mapped_len < m_len);

        /*
         * We might have done some work in above loop, so we need to query the
         * start of the physical extent, based on the origin m_lblk and m_len.
         * Let's also ensure we were able to allocate the required range for
         * mixed mapping case.
         */
        map->m_lblk = m_lblk;
        map->m_len = m_len;
        map->m_flags = 0;

        ret = ext4_map_blocks(handle, inode, map,
                              EXT4_GET_BLOCKS_QUERY_LAST_IN_LEAF);
        if (ret != m_len) {
                ext4_warning_inode(inode,
                        "allocation failed for atomic write request m_lblk:%u, m_len:%u, ret:%d\n",
                        m_lblk, m_len, ret);
                ret = -EINVAL;
        }
        return ret;

out_err:
        /* reset map before returning an error */
        map->m_lblk = m_lblk;
        map->m_len = m_len;
        map->m_flags = 0;
        return ret;
}

/*
 * ext4_map_blocks_atomic: Helper routine to ensure the entire requested
 * range in @map [lblk, lblk + len) is one single contiguous extent with no
 * mixed mappings.
 *
 * We first use m_flags passed to us by our caller (ext4_iomap_alloc()).
 * We only call EXT4_GET_BLOCKS_ZERO in the slow path, when the underlying
 * physical extent for the requested range does not have a single contiguous
 * mapping type i.e. (Hole, Mapped, or Unwritten) throughout.
 * In that case we will loop over the requested range to allocate and zero out
 * the unwritten / holes in between, to get a single mapped extent from
 * [m_lblk, m_lblk +  m_len). Note that this is only possible because we know
 * this can be called only with bigalloc enabled filesystem where the underlying
 * cluster is already allocated. This avoids allocating discontiguous extents
 * in the slow path due to multiple calls to ext4_map_blocks().
 * The slow path is mostly non-performance critical path, so it should be ok to
 * loop using ext4_map_blocks() with appropriate flags to allocate & zero the
 * underlying short holes/unwritten extents within the requested range.
 */
static int ext4_map_blocks_atomic_write(handle_t *handle, struct inode *inode,
                                struct ext4_map_blocks *map, int m_flags,
                                bool *force_commit)
{
        ext4_lblk_t m_lblk = map->m_lblk;
        unsigned int m_len = map->m_len;
        int ret = 0;

        WARN_ON_ONCE(m_len > 1 && !ext4_has_feature_bigalloc(inode->i_sb));

        ret = ext4_map_blocks(handle, inode, map, m_flags);
        if (ret < 0 || ret == m_len)
                goto out;
        /*
         * This is a mixed mapping case where we were not able to allocate
         * a single contiguous extent. In that case let's reset requested
         * mapping and call the slow path.
         */
        map->m_lblk = m_lblk;
        map->m_len = m_len;
        map->m_flags = 0;

        /*
         * slow path means we have mixed mapping, that means we will need
         * to force txn commit.
         */
        *force_commit = true;
        return ext4_map_blocks_atomic_write_slow(handle, inode, map);
out:
        return ret;
}

static int ext4_iomap_alloc(struct inode *inode, struct ext4_map_blocks *map,
                            unsigned int flags)
{
        handle_t *handle;
        int ret, dio_credits, m_flags = 0, retries = 0;
        bool force_commit = false;

        /*
         * Trim the mapping request to the maximum value that we can map at
         * once for direct I/O.
         */
        if (map->m_len > DIO_MAX_BLOCKS)
                map->m_len = DIO_MAX_BLOCKS;

        /*
         * journal credits estimation for atomic writes. We call
         * ext4_map_blocks(), to find if there could be a mixed mapping. If yes,
         * then let's assume the no. of pextents required can be m_len i.e.
         * every alternate block can be unwritten and hole.
         */
        if (flags & IOMAP_ATOMIC) {
                unsigned int orig_mlen = map->m_len;

                ret = ext4_map_blocks(NULL, inode, map, 0);
                if (ret < 0)
                        return ret;
                if (map->m_len < orig_mlen) {
                        map->m_len = orig_mlen;
                        dio_credits = ext4_meta_trans_blocks(inode, orig_mlen,
                                                             map->m_len);
                } else {
                        dio_credits = ext4_chunk_trans_blocks(inode,
                                                              map->m_len);
                }
        } else {
                dio_credits = ext4_chunk_trans_blocks(inode, map->m_len);
        }

retry:
        /*
         * Either we allocate blocks and then don't get an unwritten extent, so
         * in that case we have reserved enough credits. Or, the blocks are
         * already allocated and unwritten. In that case, the extent conversion
         * fits into the credits as well.
         */
        handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, dio_credits);
        if (IS_ERR(handle))
                return PTR_ERR(handle);

        /*
         * DAX and direct I/O are the only two operations that are currently
         * supported with IOMAP_WRITE.
         */
        WARN_ON(!(flags & (IOMAP_DAX | IOMAP_DIRECT)));
        if (flags & IOMAP_DAX)
                m_flags = EXT4_GET_BLOCKS_CREATE_ZERO;
        /*
         * We use i_size instead of i_disksize here because delalloc writeback
         * can complete at any point during the I/O and subsequently push the
         * i_disksize out to i_size. This could be beyond where direct I/O is
         * happening and thus expose allocated blocks to direct I/O reads.
         */
        else if (EXT4_LBLK_TO_B(inode, map->m_lblk) >= i_size_read(inode))
                m_flags = EXT4_GET_BLOCKS_CREATE;
        else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
                m_flags = EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT;

        if (flags & IOMAP_ATOMIC)
                ret = ext4_map_blocks_atomic_write(handle, inode, map, m_flags,
                                                   &force_commit);
        else
                ret = ext4_map_blocks(handle, inode, map, m_flags);

        /*
         * We cannot fill holes in indirect tree based inodes as that could
         * expose stale data in the case of a crash. Use the magic error code
         * to fallback to buffered I/O.
         */
        if (!m_flags && !ret)
                ret = -ENOTBLK;

        ext4_journal_stop(handle);
        if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
                goto retry;

        /*
         * Force commit the current transaction if the allocation spans a mixed
         * mapping range. This ensures any pending metadata updates (like
         * unwritten to written extents conversion) in this range are in
         * consistent state with the file data blocks, before performing the
         * actual write I/O. If the commit fails, the whole I/O must be aborted
         * to prevent any possible torn writes.
         */
        if (ret > 0 && force_commit) {
                int ret2;

                ret2 = ext4_force_commit(inode->i_sb);
                if (ret2)
                        return ret2;
        }

        return ret;
}


static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
                unsigned flags, struct iomap *iomap, struct iomap *srcmap)
{
        int ret;
        struct ext4_map_blocks map;
        u8 blkbits = inode->i_blkbits;
        unsigned int orig_mlen;

        if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
                return -EINVAL;

        if (WARN_ON_ONCE(ext4_has_inline_data(inode)))
                return -ERANGE;

        /*
         * Calculate the first and last logical blocks respectively.
         */
        map.m_lblk = offset >> blkbits;
        map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits,
                          EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
        orig_mlen = map.m_len;

        if (flags & IOMAP_WRITE) {
                /*
                 * We check here if the blocks are already allocated, then we
                 * don't need to start a journal txn and we can directly return
                 * the mapping information. This could boost performance
                 * especially in multi-threaded overwrite requests.
                 */
                if (offset + length <= i_size_read(inode)) {
                        ret = ext4_map_blocks(NULL, inode, &map, 0);
                        /*
                         * For DAX we convert extents to initialized ones before
                         * copying the data, otherwise we do it after I/O so
                         * there's no need to call into ext4_iomap_alloc().
                         */
                        if ((map.m_flags & EXT4_MAP_MAPPED) ||
                            (!(flags & IOMAP_DAX) &&
                             (map.m_flags & EXT4_MAP_UNWRITTEN))) {
                                /*
                                 * For atomic writes the entire requested
                                 * length should be mapped.
                                 */
                                if (ret == orig_mlen ||
                                    (!(flags & IOMAP_ATOMIC) && ret > 0))
                                        goto out;
                        }
                        map.m_len = orig_mlen;
                }
                ret = ext4_iomap_alloc(inode, &map, flags);
        } else {
                ret = ext4_map_blocks(NULL, inode, &map, 0);
        }

        if (ret < 0)
                return ret;
out:
        /*
         * When inline encryption is enabled, sometimes I/O to an encrypted file
         * has to be broken up to guarantee DUN contiguity.  Handle this by
         * limiting the length of the mapping returned.
         */
        map.m_len = fscrypt_limit_io_blocks(inode, map.m_lblk, map.m_len);

        /*
         * Before returning to iomap, let's ensure the allocated mapping
         * covers the entire requested length for atomic writes.
         */
        if (flags & IOMAP_ATOMIC) {
                if (map.m_len < (length >> blkbits)) {
                        WARN_ON_ONCE(1);
                        return -EINVAL;
                }
        }
        ext4_set_iomap(inode, iomap, &map, offset, length, flags);

        return 0;
}

const struct iomap_ops ext4_iomap_ops = {
        .iomap_begin            = ext4_iomap_begin,
};

static int ext4_iomap_begin_report(struct inode *inode, loff_t offset,
                                   loff_t length, unsigned int flags,
                                   struct iomap *iomap, struct iomap *srcmap)
{
        int ret;
        struct ext4_map_blocks map;
        u8 blkbits = inode->i_blkbits;

        if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
                return -EINVAL;

        if (ext4_has_inline_data(inode)) {
                ret = ext4_inline_data_iomap(inode, iomap);
                if (ret != -EAGAIN) {
                        if (ret == 0 && offset >= iomap->length)
                                ret = -ENOENT;
                        return ret;
                }
        }

        /*
         * Calculate the first and last logical block respectively.
         */
        map.m_lblk = offset >> blkbits;
        map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits,
                          EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;

        /*
         * Fiemap callers may call for offset beyond s_bitmap_maxbytes.
         * So handle it here itself instead of querying ext4_map_blocks().
         * Since ext4_map_blocks() will warn about it and will return
         * -EIO error.
         */
        if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
                struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);

                if (offset >= sbi->s_bitmap_maxbytes) {
                        map.m_flags = 0;
                        goto set_iomap;
                }
        }

        ret = ext4_map_blocks(NULL, inode, &map, 0);
        if (ret < 0)
                return ret;
set_iomap:
        ext4_set_iomap(inode, iomap, &map, offset, length, flags);

        return 0;
}

const struct iomap_ops ext4_iomap_report_ops = {
        .iomap_begin = ext4_iomap_begin_report,
};

/*
 * For data=journal mode, folio should be marked dirty only when it was
 * writeably mapped. When that happens, it was already attached to the
 * transaction and marked as jbddirty (we take care of this in
 * ext4_page_mkwrite()). On transaction commit, we writeprotect page mappings
 * so we should have nothing to do here, except for the case when someone
 * had the page pinned and dirtied the page through this pin (e.g. by doing
 * direct IO to it). In that case we'd need to attach buffers here to the
 * transaction but we cannot due to lock ordering.  We cannot just dirty the
 * folio and leave attached buffers clean, because the buffers' dirty state is
 * "definitive".  We cannot just set the buffers dirty or jbddirty because all
 * the journalling code will explode.  So what we do is to mark the folio
 * "pending dirty" and next time ext4_writepages() is called, attach buffers
 * to the transaction appropriately.
 */
static bool ext4_journalled_dirty_folio(struct address_space *mapping,
                struct folio *folio)
{
        WARN_ON_ONCE(!folio_buffers(folio));
        if (folio_maybe_dma_pinned(folio))
                folio_set_checked(folio);
        return filemap_dirty_folio(mapping, folio);
}

static bool ext4_dirty_folio(struct address_space *mapping, struct folio *folio)
{
        WARN_ON_ONCE(!folio_test_locked(folio) && !folio_test_dirty(folio));
        WARN_ON_ONCE(!folio_buffers(folio));
        return block_dirty_folio(mapping, folio);
}

static int ext4_iomap_swap_activate(struct swap_info_struct *sis,
                                    struct file *file, sector_t *span)
{
        return iomap_swapfile_activate(sis, file, span,
                                       &ext4_iomap_report_ops);
}

static const struct address_space_operations ext4_aops = {
        .read_folio             = ext4_read_folio,
        .readahead              = ext4_readahead,
        .writepages             = ext4_writepages,
        .write_begin            = ext4_write_begin,
        .write_end              = ext4_write_end,
        .dirty_folio            = ext4_dirty_folio,
        .bmap                   = ext4_bmap,
        .invalidate_folio       = ext4_invalidate_folio,
        .release_folio          = ext4_release_folio,
        .migrate_folio          = buffer_migrate_folio,
        .is_partially_uptodate  = block_is_partially_uptodate,
        .error_remove_folio     = generic_error_remove_folio,
        .swap_activate          = ext4_iomap_swap_activate,
};

static const struct address_space_operations ext4_journalled_aops = {
        .read_folio             = ext4_read_folio,
        .readahead              = ext4_readahead,
        .writepages             = ext4_writepages,
        .write_begin            = ext4_write_begin,
        .write_end              = ext4_journalled_write_end,
        .dirty_folio            = ext4_journalled_dirty_folio,
        .bmap                   = ext4_bmap,
        .invalidate_folio       = ext4_journalled_invalidate_folio,
        .release_folio          = ext4_release_folio,
        .migrate_folio          = buffer_migrate_folio_norefs,
        .is_partially_uptodate  = block_is_partially_uptodate,
        .error_remove_folio     = generic_error_remove_folio,
        .swap_activate          = ext4_iomap_swap_activate,
};

static const struct address_space_operations ext4_da_aops = {
        .read_folio             = ext4_read_folio,
        .readahead              = ext4_readahead,
        .writepages             = ext4_writepages,
        .write_begin            = ext4_da_write_begin,
        .write_end              = ext4_da_write_end,
        .dirty_folio            = ext4_dirty_folio,
        .bmap                   = ext4_bmap,
        .invalidate_folio       = ext4_invalidate_folio,
        .release_folio          = ext4_release_folio,
        .migrate_folio          = buffer_migrate_folio,
        .is_partially_uptodate  = block_is_partially_uptodate,
        .error_remove_folio     = generic_error_remove_folio,
        .swap_activate          = ext4_iomap_swap_activate,
};

static const struct address_space_operations ext4_dax_aops = {
        .writepages             = ext4_dax_writepages,
        .dirty_folio            = noop_dirty_folio,
        .bmap                   = ext4_bmap,
        .swap_activate          = ext4_iomap_swap_activate,
};

void ext4_set_aops(struct inode *inode)
{
        switch (ext4_inode_journal_mode(inode)) {
        case EXT4_INODE_ORDERED_DATA_MODE:
        case EXT4_INODE_WRITEBACK_DATA_MODE:
                break;
        case EXT4_INODE_JOURNAL_DATA_MODE:
                inode->i_mapping->a_ops = &ext4_journalled_aops;
                return;
        default:
                BUG();
        }
        if (IS_DAX(inode))
                inode->i_mapping->a_ops = &ext4_dax_aops;
        else if (test_opt(inode->i_sb, DELALLOC))
                inode->i_mapping->a_ops = &ext4_da_aops;
        else
                inode->i_mapping->a_ops = &ext4_aops;
}

/*
 * Here we can't skip an unwritten buffer even though it usually reads zero
 * because it might have data in pagecache (eg, if called from ext4_zero_range,
 * ext4_punch_hole, etc) which needs to be properly zeroed out. Otherwise a
 * racing writeback can come later and flush the stale pagecache to disk.
 */
static int __ext4_block_zero_page_range(handle_t *handle,
                struct address_space *mapping, loff_t from, loff_t length)
{
        unsigned int offset, blocksize, pos;
        ext4_lblk_t iblock;
        struct inode *inode = mapping->host;
        struct buffer_head *bh;
        struct folio *folio;
        int err = 0;

        folio = __filemap_get_folio(mapping, from >> PAGE_SHIFT,
                                    FGP_LOCK | FGP_ACCESSED | FGP_CREAT,
                                    mapping_gfp_constraint(mapping, ~__GFP_FS));
        if (IS_ERR(folio))
                return PTR_ERR(folio);

        blocksize = inode->i_sb->s_blocksize;

        iblock = EXT4_PG_TO_LBLK(inode, folio->index);

        bh = folio_buffers(folio);
        if (!bh)
                bh = create_empty_buffers(folio, blocksize, 0);

        /* Find the buffer that contains "offset" */
        offset = offset_in_folio(folio, from);
        pos = blocksize;
        while (offset >= pos) {
                bh = bh->b_this_page;
                iblock++;
                pos += blocksize;
        }
        if (buffer_freed(bh)) {
                BUFFER_TRACE(bh, "freed: skip");
                goto unlock;
        }
        if (!buffer_mapped(bh)) {
                BUFFER_TRACE(bh, "unmapped");
                ext4_get_block(inode, iblock, bh, 0);
                /* unmapped? It's a hole - nothing to do */
                if (!buffer_mapped(bh)) {
                        BUFFER_TRACE(bh, "still unmapped");
                        goto unlock;
                }
        }

        /* Ok, it's mapped. Make sure it's up-to-date */
        if (folio_test_uptodate(folio))
                set_buffer_uptodate(bh);

        if (!buffer_uptodate(bh)) {
                err = ext4_read_bh_lock(bh, 0, true);
                if (err)
                        goto unlock;
                if (fscrypt_inode_uses_fs_layer_crypto(inode)) {
                        /* We expect the key to be set. */
                        BUG_ON(!fscrypt_has_encryption_key(inode));
                        err = fscrypt_decrypt_pagecache_blocks(folio,
                                                               blocksize,
                                                               bh_offset(bh));
                        if (err) {
                                clear_buffer_uptodate(bh);
                                goto unlock;
                        }
                }
        }
        if (ext4_should_journal_data(inode)) {
                BUFFER_TRACE(bh, "get write access");
                err = ext4_journal_get_write_access(handle, inode->i_sb, bh,
                                                    EXT4_JTR_NONE);
                if (err)
                        goto unlock;
        }
        folio_zero_range(folio, offset, length);
        BUFFER_TRACE(bh, "zeroed end of block");

        if (ext4_should_journal_data(inode)) {
                err = ext4_dirty_journalled_data(handle, bh);
        } else {
                mark_buffer_dirty(bh);
                /*
                 * Only the written block requires ordered data to prevent
                 * exposing stale data.
                 */
                if (!buffer_unwritten(bh) && !buffer_delay(bh) &&
                    ext4_should_order_data(inode))
                        err = ext4_jbd2_inode_add_write(handle, inode, from,
                                        length);
        }

unlock:
        folio_unlock(folio);
        folio_put(folio);
        return err;
}

/*
 * ext4_block_zero_page_range() zeros out a mapping of length 'length'
 * starting from file offset 'from'.  The range to be zero'd must
 * be contained with in one block.  If the specified range exceeds
 * the end of the block it will be shortened to end of the block
 * that corresponds to 'from'
 */
static int ext4_block_zero_page_range(handle_t *handle,
                struct address_space *mapping, loff_t from, loff_t length)
{
        struct inode *inode = mapping->host;
        unsigned blocksize = inode->i_sb->s_blocksize;
        unsigned int max = blocksize - (from & (blocksize - 1));

        /*
         * correct length if it does not fall between
         * 'from' and the end of the block
         */
        if (length > max || length < 0)
                length = max;

        if (IS_DAX(inode)) {
                return dax_zero_range(inode, from, length, NULL,
                                      &ext4_iomap_ops);
        }
        return __ext4_block_zero_page_range(handle, mapping, from, length);
}

/*
 * ext4_block_truncate_page() zeroes out a mapping from file offset `from'
 * up to the end of the block which corresponds to `from'.
 * This required during truncate. We need to physically zero the tail end
 * of that block so it doesn't yield old data if the file is later grown.
 */
static int ext4_block_truncate_page(handle_t *handle,
                struct address_space *mapping, loff_t from)
{
        unsigned length;
        unsigned blocksize;
        struct inode *inode = mapping->host;

        /* If we are processing an encrypted inode during orphan list handling */
        if (IS_ENCRYPTED(inode) && !fscrypt_has_encryption_key(inode))
                return 0;

        blocksize = i_blocksize(inode);
        length = blocksize - (from & (blocksize - 1));

        return ext4_block_zero_page_range(handle, mapping, from, length);
}

int ext4_zero_partial_blocks(handle_t *handle, struct inode *inode,
                             loff_t lstart, loff_t length)
{
        struct super_block *sb = inode->i_sb;
        struct address_space *mapping = inode->i_mapping;
        unsigned partial_start, partial_end;
        ext4_fsblk_t start, end;
        loff_t byte_end = (lstart + length - 1);
        int err = 0;

        partial_start = lstart & (sb->s_blocksize - 1);
        partial_end = byte_end & (sb->s_blocksize - 1);

        start = lstart >> sb->s_blocksize_bits;
        end = byte_end >> sb->s_blocksize_bits;

        /* Handle partial zero within the single block */
        if (start == end &&
            (partial_start || (partial_end != sb->s_blocksize - 1))) {
                err = ext4_block_zero_page_range(handle, mapping,
                                                 lstart, length);
                return err;
        }
        /* Handle partial zero out on the start of the range */
        if (partial_start) {
                err = ext4_block_zero_page_range(handle, mapping,
                                                 lstart, sb->s_blocksize);
                if (err)
                        return err;
        }
        /* Handle partial zero out on the end of the range */
        if (partial_end != sb->s_blocksize - 1)
                err = ext4_block_zero_page_range(handle, mapping,
                                                 byte_end - partial_end,
                                                 partial_end + 1);
        return err;
}

int ext4_can_truncate(struct inode *inode)
{
        if (S_ISREG(inode->i_mode))
                return 1;
        if (S_ISDIR(inode->i_mode))
                return 1;
        if (S_ISLNK(inode->i_mode))
                return !ext4_inode_is_fast_symlink(inode);
        return 0;
}

/*
 * We have to make sure i_disksize gets properly updated before we truncate
 * page cache due to hole punching or zero range. Otherwise i_disksize update
 * can get lost as it may have been postponed to submission of writeback but
 * that will never happen if we remove the folio containing i_size from the
 * page cache. Also if we punch hole within i_size but above i_disksize,
 * following ext4_page_mkwrite() may mistakenly allocate written blocks over
 * the hole and thus introduce allocated blocks beyond i_disksize which is
 * not allowed (e2fsck would complain in case of crash).
 */
int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset,
                                      loff_t len)
{
        handle_t *handle;
        int ret;

        loff_t size = i_size_read(inode);

        WARN_ON(!inode_is_locked(inode));
        if (offset > size)
                return 0;

        if (offset + len < size)
                size = offset + len;
        if (EXT4_I(inode)->i_disksize >= size)
                return 0;

        handle = ext4_journal_start(inode, EXT4_HT_MISC, 1);
        if (IS_ERR(handle))
                return PTR_ERR(handle);
        ext4_update_i_disksize(inode, size);
        ret = ext4_mark_inode_dirty(handle, inode);
        ext4_journal_stop(handle);

        return ret;
}

static inline void ext4_truncate_folio(struct inode *inode,
                                       loff_t start, loff_t end)
{
        unsigned long blocksize = i_blocksize(inode);
        struct folio *folio;

        /* Nothing to be done if no complete block needs to be truncated. */
        if (round_up(start, blocksize) >= round_down(end, blocksize))
                return;

        folio = filemap_lock_folio(inode->i_mapping, start >> PAGE_SHIFT);
        if (IS_ERR(folio))
                return;

        if (folio_mkclean(folio))
                folio_mark_dirty(folio);
        folio_unlock(folio);
        folio_put(folio);
}

int ext4_truncate_page_cache_block_range(struct inode *inode,
                                         loff_t start, loff_t end)
{
        unsigned long blocksize = i_blocksize(inode);
        int ret;

        /*
         * For journalled data we need to write (and checkpoint) pages
         * before discarding page cache to avoid inconsitent data on disk
         * in case of crash before freeing or unwritten converting trans
         * is committed.
         */
        if (ext4_should_journal_data(inode)) {
                ret = filemap_write_and_wait_range(inode->i_mapping, start,
                                                   end - 1);
                if (ret)
                        return ret;
                goto truncate_pagecache;
        }

        /*
         * If the block size is less than the page size, the file's mapped
         * blocks within one page could be freed or converted to unwritten.
         * So it's necessary to remove writable userspace mappings, and then
         * ext4_page_mkwrite() can be called during subsequent write access
         * to these partial folios.
         */
        if (!IS_ALIGNED(start | end, PAGE_SIZE) &&
            blocksize < PAGE_SIZE && start < inode->i_size) {
                loff_t page_boundary = round_up(start, PAGE_SIZE);

                ext4_truncate_folio(inode, start, min(page_boundary, end));
                if (end > page_boundary)
                        ext4_truncate_folio(inode,
                                            round_down(end, PAGE_SIZE), end);
        }

truncate_pagecache:
        truncate_pagecache_range(inode, start, end - 1);
        return 0;
}

static void ext4_wait_dax_page(struct inode *inode)
{
        filemap_invalidate_unlock(inode->i_mapping);
        schedule();
        filemap_invalidate_lock(inode->i_mapping);
}

int ext4_break_layouts(struct inode *inode)
{
        if (WARN_ON_ONCE(!rwsem_is_locked(&inode->i_mapping->invalidate_lock)))
                return -EINVAL;

        return dax_break_layout_inode(inode, ext4_wait_dax_page);
}

/*
 * ext4_punch_hole: punches a hole in a file by releasing the blocks
 * associated with the given offset and length
 *
 * @inode:  File inode
 * @offset: The offset where the hole will begin
 * @len:    The length of the hole
 *
 * Returns: 0 on success or negative on failure
 */

int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
{
        struct inode *inode = file_inode(file);
        struct super_block *sb = inode->i_sb;
        ext4_lblk_t start_lblk, end_lblk;
        loff_t max_end = sb->s_maxbytes;
        loff_t end = offset + length;
        handle_t *handle;
        unsigned int credits;
        int ret;

        trace_ext4_punch_hole(inode, offset, length, 0);
        WARN_ON_ONCE(!inode_is_locked(inode));

        /*
         * For indirect-block based inodes, make sure that the hole within
         * one block before last range.
         */
        if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
                max_end = EXT4_SB(sb)->s_bitmap_maxbytes - sb->s_blocksize;

        /* No need to punch hole beyond i_size */
        if (offset >= inode->i_size || offset >= max_end)
                return 0;

        /*
         * If the hole extends beyond i_size, set the hole to end after
         * the block that contains i_size to save pointless tail block zeroing.
         */
        if (end >= inode->i_size)
                end = round_up(inode->i_size, sb->s_blocksize);
        if (end > max_end)
                end = max_end;
        length = end - offset;

        /*
         * Attach jinode to inode for jbd2 if we do any zeroing of partial
         * block.
         */
        if (!IS_ALIGNED(offset | end, sb->s_blocksize)) {
                ret = ext4_inode_attach_jinode(inode);
                if (ret < 0)
                        return ret;
        }


        ret = ext4_update_disksize_before_punch(inode, offset, length);
        if (ret)
                return ret;

        /* Now release the pages and zero block aligned part of pages*/
        ret = ext4_truncate_page_cache_block_range(inode, offset, end);
        if (ret)
                return ret;

        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
                credits = ext4_chunk_trans_extent(inode, 2);
        else
                credits = ext4_blocks_for_truncate(inode);
        handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
        if (IS_ERR(handle)) {
                ret = PTR_ERR(handle);
                ext4_std_error(sb, ret);
                return ret;
        }

        ret = ext4_zero_partial_blocks(handle, inode, offset, length);
        if (ret)
                goto out_handle;

        /* If there are blocks to remove, do it */
        start_lblk = EXT4_B_TO_LBLK(inode, offset);
        end_lblk = end >> inode->i_blkbits;

        if (end_lblk > start_lblk) {
                ext4_lblk_t hole_len = end_lblk - start_lblk;

                ext4_fc_track_inode(handle, inode);
                ext4_check_map_extents_env(inode);
                down_write(&EXT4_I(inode)->i_data_sem);
                ext4_discard_preallocations(inode);

                ext4_es_remove_extent(inode, start_lblk, hole_len);

                if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
                        ret = ext4_ext_remove_space(inode, start_lblk,
                                                    end_lblk - 1);
                else
                        ret = ext4_ind_remove_space(handle, inode, start_lblk,
                                                    end_lblk);
                if (ret) {
                        up_write(&EXT4_I(inode)->i_data_sem);
                        goto out_handle;
                }

                ext4_es_insert_extent(inode, start_lblk, hole_len, ~0,
                                      EXTENT_STATUS_HOLE, 0);
                up_write(&EXT4_I(inode)->i_data_sem);
        }
        ext4_fc_track_range(handle, inode, start_lblk, end_lblk);

        ret = ext4_mark_inode_dirty(handle, inode);
        if (unlikely(ret))
                goto out_handle;

        ext4_update_inode_fsync_trans(handle, inode, 1);
        if (IS_SYNC(inode))
                ext4_handle_sync(handle);
out_handle:
        ext4_journal_stop(handle);
        return ret;
}

int ext4_inode_attach_jinode(struct inode *inode)
{
        struct ext4_inode_info *ei = EXT4_I(inode);
        struct jbd2_inode *jinode;

        if (ei->jinode || !EXT4_SB(inode->i_sb)->s_journal)
                return 0;

        jinode = jbd2_alloc_inode(GFP_KERNEL);
        spin_lock(&inode->i_lock);
        if (!ei->jinode) {
                if (!jinode) {
                        spin_unlock(&inode->i_lock);
                        return -ENOMEM;
                }
                jbd2_journal_init_jbd_inode(jinode, inode);
                /*
                 * Publish ->jinode only after it is fully initialized so that
                 * readers never observe a partially initialized jbd2_inode.
                 */
                smp_wmb();
                WRITE_ONCE(ei->jinode, jinode);
                jinode = NULL;
        }
        spin_unlock(&inode->i_lock);
        if (unlikely(jinode != NULL))
                jbd2_free_inode(jinode);
        return 0;
}

/*
 * ext4_truncate()
 *
 * We block out ext4_get_block() block instantiations across the entire
 * transaction, and VFS/VM ensures that ext4_truncate() cannot run
 * simultaneously on behalf of the same inode.
 *
 * As we work through the truncate and commit bits of it to the journal there
 * is one core, guiding principle: the file's tree must always be consistent on
 * disk.  We must be able to restart the truncate after a crash.
 *
 * The file's tree may be transiently inconsistent in memory (although it
 * probably isn't), but whenever we close off and commit a journal transaction,
 * the contents of (the filesystem + the journal) must be consistent and
 * restartable.  It's pretty simple, really: bottom up, right to left (although
 * left-to-right works OK too).
 *
 * Note that at recovery time, journal replay occurs *before* the restart of
 * truncate against the orphan inode list.
 *
 * The committed inode has the new, desired i_size (which is the same as
 * i_disksize in this case).  After a crash, ext4_orphan_cleanup() will see
 * that this inode's truncate did not complete and it will again call
 * ext4_truncate() to have another go.  So there will be instantiated blocks
 * to the right of the truncation point in a crashed ext4 filesystem.  But
 * that's fine - as long as they are linked from the inode, the post-crash
 * ext4_truncate() run will find them and release them.
 */
int ext4_truncate(struct inode *inode)
{
        struct ext4_inode_info *ei = EXT4_I(inode);
        unsigned int credits;
        int err = 0, err2;
        handle_t *handle;
        struct address_space *mapping = inode->i_mapping;

        /*
         * There is a possibility that we're either freeing the inode
         * or it's a completely new inode. In those cases we might not
         * have i_rwsem locked because it's not necessary.
         */
        if (!(inode_state_read_once(inode) & (I_NEW | I_FREEING)))
                WARN_ON(!inode_is_locked(inode));
        trace_ext4_truncate_enter(inode);

        if (!ext4_can_truncate(inode))
                goto out_trace;

        if (inode->i_size == 0 && !test_opt(inode->i_sb, NO_AUTO_DA_ALLOC))
                ext4_set_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);

        if (ext4_has_inline_data(inode)) {
                int has_inline = 1;

                err = ext4_inline_data_truncate(inode, &has_inline);
                if (err || has_inline)
                        goto out_trace;
        }

        /* If we zero-out tail of the page, we have to create jinode for jbd2 */
        if (inode->i_size & (inode->i_sb->s_blocksize - 1)) {
                err = ext4_inode_attach_jinode(inode);
                if (err)
                        goto out_trace;
        }

        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
                credits = ext4_chunk_trans_extent(inode, 1);
        else
                credits = ext4_blocks_for_truncate(inode);

        handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
        if (IS_ERR(handle)) {
                err = PTR_ERR(handle);
                goto out_trace;
        }

        if (inode->i_size & (inode->i_sb->s_blocksize - 1))
                ext4_block_truncate_page(handle, mapping, inode->i_size);

        /*
         * We add the inode to the orphan list, so that if this
         * truncate spans multiple transactions, and we crash, we will
         * resume the truncate when the filesystem recovers.  It also
         * marks the inode dirty, to catch the new size.
         *
         * Implication: the file must always be in a sane, consistent
         * truncatable state while each transaction commits.
         */
        err = ext4_orphan_add(handle, inode);
        if (err)
                goto out_stop;

        ext4_fc_track_inode(handle, inode);
        ext4_check_map_extents_env(inode);

        down_write(&EXT4_I(inode)->i_data_sem);
        ext4_discard_preallocations(inode);

        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
                err = ext4_ext_truncate(handle, inode);
        else
                ext4_ind_truncate(handle, inode);

        up_write(&ei->i_data_sem);
        if (err)
                goto out_stop;

        if (IS_SYNC(inode))
                ext4_handle_sync(handle);

out_stop:
        /*
         * If this was a simple ftruncate() and the file will remain alive,
         * then we need to clear up the orphan record which we created above.
         * However, if this was a real unlink then we were called by
         * ext4_evict_inode(), and we allow that function to clean up the
         * orphan info for us.
         */
        if (inode->i_nlink)
                ext4_orphan_del(handle, inode);

        inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
        err2 = ext4_mark_inode_dirty(handle, inode);
        if (unlikely(err2 && !err))
                err = err2;
        ext4_journal_stop(handle);

out_trace:
        trace_ext4_truncate_exit(inode);
        return err;
}

static inline u64 ext4_inode_peek_iversion(const struct inode *inode)
{
        if (unlikely(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL))
                return inode_peek_iversion_raw(inode);
        else
                return inode_peek_iversion(inode);
}

static int ext4_inode_blocks_set(struct ext4_inode *raw_inode,
                                 struct ext4_inode_info *ei)
{
        struct inode *inode = &(ei->vfs_inode);
        u64 i_blocks = READ_ONCE(inode->i_blocks);
        struct super_block *sb = inode->i_sb;

        if (i_blocks <= ~0U) {
                /*
                 * i_blocks can be represented in a 32 bit variable
                 * as multiple of 512 bytes
                 */
                raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
                raw_inode->i_blocks_high = 0;
                ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
                return 0;
        }

        /*
         * This should never happen since sb->s_maxbytes should not have
         * allowed this, sb->s_maxbytes was set according to the huge_file
         * feature in ext4_fill_super().
         */
        if (!ext4_has_feature_huge_file(sb))
                return -EFSCORRUPTED;

        if (i_blocks <= 0xffffffffffffULL) {
                /*
                 * i_blocks can be represented in a 48 bit variable
                 * as multiple of 512 bytes
                 */
                raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
                raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
                ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
        } else {
                ext4_set_inode_flag(inode, EXT4_INODE_HUGE_FILE);
                /* i_block is stored in file system block size */
                i_blocks = i_blocks >> (inode->i_blkbits - 9);
                raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
                raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
        }
        return 0;
}

static int ext4_fill_raw_inode(struct inode *inode, struct ext4_inode *raw_inode)
{
        struct ext4_inode_info *ei = EXT4_I(inode);
        uid_t i_uid;
        gid_t i_gid;
        projid_t i_projid;
        int block;
        int err;

        err = ext4_inode_blocks_set(raw_inode, ei);

        raw_inode->i_mode = cpu_to_le16(inode->i_mode);
        i_uid = i_uid_read(inode);
        i_gid = i_gid_read(inode);
        i_projid = from_kprojid(&init_user_ns, ei->i_projid);
        if (!(test_opt(inode->i_sb, NO_UID32))) {
                raw_inode->i_uid_low = cpu_to_le16(low_16_bits(i_uid));
                raw_inode->i_gid_low = cpu_to_le16(low_16_bits(i_gid));
                /*
                 * Fix up interoperability with old kernels. Otherwise,
                 * old inodes get re-used with the upper 16 bits of the
                 * uid/gid intact.
                 */
                if (ei->i_dtime && !ext4_inode_orphan_tracked(inode)) {
                        raw_inode->i_uid_high = 0;
                        raw_inode->i_gid_high = 0;
                } else {
                        raw_inode->i_uid_high =
                                cpu_to_le16(high_16_bits(i_uid));
                        raw_inode->i_gid_high =
                                cpu_to_le16(high_16_bits(i_gid));
                }
        } else {
                raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(i_uid));
                raw_inode->i_gid_low = cpu_to_le16(fs_high2lowgid(i_gid));
                raw_inode->i_uid_high = 0;
                raw_inode->i_gid_high = 0;
        }
        raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);

        EXT4_INODE_SET_CTIME(inode, raw_inode);
        EXT4_INODE_SET_MTIME(inode, raw_inode);
        EXT4_INODE_SET_ATIME(inode, raw_inode);
        EXT4_EINODE_SET_XTIME(i_crtime, ei, raw_inode);

        raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
        raw_inode->i_flags = cpu_to_le32(ei->i_flags & 0xFFFFFFFF);
        if (likely(!test_opt2(inode->i_sb, HURD_COMPAT)))
                raw_inode->i_file_acl_high =
                        cpu_to_le16(ei->i_file_acl >> 32);
        raw_inode->i_file_acl_lo = cpu_to_le32(ei->i_file_acl);
        ext4_isize_set(raw_inode, ei->i_disksize);

        raw_inode->i_generation = cpu_to_le32(inode->i_generation);
        if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
                if (old_valid_dev(inode->i_rdev)) {
                        raw_inode->i_block[0] =
                                cpu_to_le32(old_encode_dev(inode->i_rdev));
                        raw_inode->i_block[1] = 0;
                } else {
                        raw_inode->i_block[0] = 0;
                        raw_inode->i_block[1] =
                                cpu_to_le32(new_encode_dev(inode->i_rdev));
                        raw_inode->i_block[2] = 0;
                }
        } else if (!ext4_has_inline_data(inode)) {
                for (block = 0; block < EXT4_N_BLOCKS; block++)
                        raw_inode->i_block[block] = ei->i_data[block];
        }

        if (likely(!test_opt2(inode->i_sb, HURD_COMPAT))) {
                u64 ivers = ext4_inode_peek_iversion(inode);

                raw_inode->i_disk_version = cpu_to_le32(ivers);
                if (ei->i_extra_isize) {
                        if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
                                raw_inode->i_version_hi =
                                        cpu_to_le32(ivers >> 32);
                        raw_inode->i_extra_isize =
                                cpu_to_le16(ei->i_extra_isize);
                }
        }

        if (i_projid != EXT4_DEF_PROJID &&
            !ext4_has_feature_project(inode->i_sb))
                err = err ?: -EFSCORRUPTED;

        if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
            EXT4_FITS_IN_INODE(raw_inode, ei, i_projid))
                raw_inode->i_projid = cpu_to_le32(i_projid);

        ext4_inode_csum_set(inode, raw_inode, ei);
        return err;
}

/*
 * ext4_get_inode_loc returns with an extra refcount against the inode's
 * underlying buffer_head on success. If we pass 'inode' and it does not
 * have in-inode xattr, we have all inode data in memory that is needed
 * to recreate the on-disk version of this inode.
 */
static int __ext4_get_inode_loc(struct super_block *sb, unsigned long ino,
                                struct inode *inode, struct ext4_iloc *iloc,
                                ext4_fsblk_t *ret_block)
{
        struct ext4_group_desc  *gdp;
        struct buffer_head      *bh;
        ext4_fsblk_t            block;
        struct blk_plug         plug;
        int                     inodes_per_block, inode_offset;

        iloc->bh = NULL;
        if (ino < EXT4_ROOT_INO ||
            ino > le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count))
                return -EFSCORRUPTED;

        iloc->block_group = (ino - 1) / EXT4_INODES_PER_GROUP(sb);
        gdp = ext4_get_group_desc(sb, iloc->block_group, NULL);
        if (!gdp)
                return -EIO;

        /*
         * Figure out the offset within the block group inode table
         */
        inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
        inode_offset = ((ino - 1) %
                        EXT4_INODES_PER_GROUP(sb));
        iloc->offset = (inode_offset % inodes_per_block) * EXT4_INODE_SIZE(sb);

        block = ext4_inode_table(sb, gdp);
        if ((block <= le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) ||
            (block >= ext4_blocks_count(EXT4_SB(sb)->s_es))) {
                ext4_error(sb, "Invalid inode table block %llu in "
                           "block_group %u", block, iloc->block_group);
                return -EFSCORRUPTED;
        }
        block += (inode_offset / inodes_per_block);

        bh = sb_getblk(sb, block);
        if (unlikely(!bh))
                return -ENOMEM;
        if (ext4_buffer_uptodate(bh))
                goto has_buffer;

        lock_buffer(bh);
        if (ext4_buffer_uptodate(bh)) {
                /* Someone brought it uptodate while we waited */
                unlock_buffer(bh);
                goto has_buffer;
        }

        /*
         * If we have all information of the inode in memory and this
         * is the only valid inode in the block, we need not read the
         * block.
         */
        if (inode && !ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
                struct buffer_head *bitmap_bh;
                int i, start;

                start = inode_offset & ~(inodes_per_block - 1);

                /* Is the inode bitmap in cache? */
                bitmap_bh = sb_getblk(sb, ext4_inode_bitmap(sb, gdp));
                if (unlikely(!bitmap_bh))
                        goto make_io;

                /*
                 * If the inode bitmap isn't in cache then the
                 * optimisation may end up performing two reads instead
                 * of one, so skip it.
                 */
                if (!buffer_uptodate(bitmap_bh)) {
                        brelse(bitmap_bh);
                        goto make_io;
                }
                for (i = start; i < start + inodes_per_block; i++) {
                        if (i == inode_offset)
                                continue;
                        if (ext4_test_bit(i, bitmap_bh->b_data))
                                break;
                }
                brelse(bitmap_bh);
                if (i == start + inodes_per_block) {
                        struct ext4_inode *raw_inode =
                                (struct ext4_inode *) (bh->b_data + iloc->offset);

                        /* all other inodes are free, so skip I/O */
                        memset(bh->b_data, 0, bh->b_size);
                        if (!ext4_test_inode_state(inode, EXT4_STATE_NEW))
                                ext4_fill_raw_inode(inode, raw_inode);
                        set_buffer_uptodate(bh);
                        unlock_buffer(bh);
                        goto has_buffer;
                }
        }

make_io:
        /*
         * If we need to do any I/O, try to pre-readahead extra
         * blocks from the inode table.
         */
        blk_start_plug(&plug);
        if (EXT4_SB(sb)->s_inode_readahead_blks) {
                ext4_fsblk_t b, end, table;
                unsigned num;
                __u32 ra_blks = EXT4_SB(sb)->s_inode_readahead_blks;

                table = ext4_inode_table(sb, gdp);
                /* s_inode_readahead_blks is always a power of 2 */
                b = block & ~((ext4_fsblk_t) ra_blks - 1);
                if (table > b)
                        b = table;
                end = b + ra_blks;
                num = EXT4_INODES_PER_GROUP(sb);
                if (ext4_has_group_desc_csum(sb))
                        num -= ext4_itable_unused_count(sb, gdp);
                table += num / inodes_per_block;
                if (end > table)
                        end = table;
                while (b <= end)
                        ext4_sb_breadahead_unmovable(sb, b++);
        }

        /*
         * There are other valid inodes in the buffer, this inode
         * has in-inode xattrs, or we don't have this inode in memory.
         * Read the block from disk.
         */
        trace_ext4_load_inode(sb, ino);
        ext4_read_bh_nowait(bh, REQ_META | REQ_PRIO, NULL,
                            ext4_simulate_fail(sb, EXT4_SIM_INODE_EIO));
        blk_finish_plug(&plug);
        wait_on_buffer(bh);
        if (!buffer_uptodate(bh)) {
                if (ret_block)
                        *ret_block = block;
                brelse(bh);
                return -EIO;
        }
has_buffer:
        iloc->bh = bh;
        return 0;
}

static int __ext4_get_inode_loc_noinmem(struct inode *inode,
                                        struct ext4_iloc *iloc)
{
        ext4_fsblk_t err_blk = 0;
        int ret;

        ret = __ext4_get_inode_loc(inode->i_sb, inode->i_ino, NULL, iloc,
                                        &err_blk);

        if (ret == -EIO)
                ext4_error_inode_block(inode, err_blk, EIO,
                                        "unable to read itable block");

        return ret;
}

int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
{
        ext4_fsblk_t err_blk = 0;
        int ret;

        ret = __ext4_get_inode_loc(inode->i_sb, inode->i_ino, inode, iloc,
                                        &err_blk);

        if (ret == -EIO)
                ext4_error_inode_block(inode, err_blk, EIO,
                                        "unable to read itable block");

        return ret;
}


int ext4_get_fc_inode_loc(struct super_block *sb, unsigned long ino,
                          struct ext4_iloc *iloc)
{
        return __ext4_get_inode_loc(sb, ino, NULL, iloc, NULL);
}

static bool ext4_should_enable_dax(struct inode *inode)
{
        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);

        if (test_opt2(inode->i_sb, DAX_NEVER))
                return false;
        if (!S_ISREG(inode->i_mode))
                return false;
        if (ext4_should_journal_data(inode))
                return false;
        if (ext4_has_inline_data(inode))
                return false;
        if (ext4_test_inode_flag(inode, EXT4_INODE_ENCRYPT))
                return false;
        if (ext4_test_inode_flag(inode, EXT4_INODE_VERITY))
                return false;
        if (!test_bit(EXT4_FLAGS_BDEV_IS_DAX, &sbi->s_ext4_flags))
                return false;
        if (test_opt(inode->i_sb, DAX_ALWAYS))
                return true;

        return ext4_test_inode_flag(inode, EXT4_INODE_DAX);
}

void ext4_set_inode_flags(struct inode *inode, bool init)
{
        unsigned int flags = EXT4_I(inode)->i_flags;
        unsigned int new_fl = 0;

        WARN_ON_ONCE(IS_DAX(inode) && init);

        if (flags & EXT4_SYNC_FL)
                new_fl |= S_SYNC;
        if (flags & EXT4_APPEND_FL)
                new_fl |= S_APPEND;
        if (flags & EXT4_IMMUTABLE_FL)
                new_fl |= S_IMMUTABLE;
        if (flags & EXT4_NOATIME_FL)
                new_fl |= S_NOATIME;
        if (flags & EXT4_DIRSYNC_FL)
                new_fl |= S_DIRSYNC;

        /* Because of the way inode_set_flags() works we must preserve S_DAX
         * here if already set. */
        new_fl |= (inode->i_flags & S_DAX);
        if (init && ext4_should_enable_dax(inode))
                new_fl |= S_DAX;

        if (flags & EXT4_ENCRYPT_FL)
                new_fl |= S_ENCRYPTED;
        if (flags & EXT4_CASEFOLD_FL)
                new_fl |= S_CASEFOLD;
        if (flags & EXT4_VERITY_FL)
                new_fl |= S_VERITY;
        inode_set_flags(inode, new_fl,
                        S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|S_DAX|
                        S_ENCRYPTED|S_CASEFOLD|S_VERITY);
}

static blkcnt_t ext4_inode_blocks(struct ext4_inode *raw_inode,
                                  struct ext4_inode_info *ei)
{
        blkcnt_t i_blocks ;
        struct inode *inode = &(ei->vfs_inode);
        struct super_block *sb = inode->i_sb;

        if (ext4_has_feature_huge_file(sb)) {
                /* we are using combined 48 bit field */
                i_blocks = ((u64)le16_to_cpu(raw_inode->i_blocks_high)) << 32 |
                                        le32_to_cpu(raw_inode->i_blocks_lo);
                if (ext4_test_inode_flag(inode, EXT4_INODE_HUGE_FILE)) {
                        /* i_blocks represent file system block size */
                        return i_blocks  << (inode->i_blkbits - 9);
                } else {
                        return i_blocks;
                }
        } else {
                return le32_to_cpu(raw_inode->i_blocks_lo);
        }
}

static inline int ext4_iget_extra_inode(struct inode *inode,
                                         struct ext4_inode *raw_inode,
                                         struct ext4_inode_info *ei)
{
        __le32 *magic = (void *)raw_inode +
                        EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize;

        if (EXT4_INODE_HAS_XATTR_SPACE(inode)  &&
            *magic == cpu_to_le32(EXT4_XATTR_MAGIC)) {
                int err;

                err = xattr_check_inode(inode, IHDR(inode, raw_inode),
                                        ITAIL(inode, raw_inode));
                if (err)
                        return err;

                ext4_set_inode_state(inode, EXT4_STATE_XATTR);
                err = ext4_find_inline_data_nolock(inode);
                if (!err && ext4_has_inline_data(inode))
                        ext4_set_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
                return err;
        } else
                EXT4_I(inode)->i_inline_off = 0;
        return 0;
}

int ext4_get_projid(struct inode *inode, kprojid_t *projid)
{
        if (!ext4_has_feature_project(inode->i_sb))
                return -EOPNOTSUPP;
        *projid = EXT4_I(inode)->i_projid;
        return 0;
}

/*
 * ext4 has self-managed i_version for ea inodes, it stores the lower 32bit of
 * refcount in i_version, so use raw values if inode has EXT4_EA_INODE_FL flag
 * set.
 */
static inline void ext4_inode_set_iversion_queried(struct inode *inode, u64 val)
{
        if (unlikely(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL))
                inode_set_iversion_raw(inode, val);
        else
                inode_set_iversion_queried(inode, val);
}

static int check_igot_inode(struct inode *inode, ext4_iget_flags flags,
                            const char *function, unsigned int line)
{
        const char *err_str;

        if (flags & EXT4_IGET_EA_INODE) {
                if (!(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL)) {
                        err_str = "missing EA_INODE flag";
                        goto error;
                }
                if (ext4_test_inode_state(inode, EXT4_STATE_XATTR) ||
                    EXT4_I(inode)->i_file_acl) {
                        err_str = "ea_inode with extended attributes";
                        goto error;
                }
        } else {
                if ((EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL)) {
                        /*
                         * open_by_handle_at() could provide an old inode number
                         * that has since been reused for an ea_inode; this does
                         * not indicate filesystem corruption
                         */
                        if (flags & EXT4_IGET_HANDLE)
                                return -ESTALE;
                        err_str = "unexpected EA_INODE flag";
                        goto error;
                }
        }
        if (is_bad_inode(inode) && !(flags & EXT4_IGET_BAD)) {
                err_str = "unexpected bad inode w/o EXT4_IGET_BAD";
                goto error;
        }
        return 0;

error:
        ext4_error_inode(inode, function, line, 0, "%s", err_str);
        return -EFSCORRUPTED;
}

void ext4_set_inode_mapping_order(struct inode *inode)
{
        struct super_block *sb = inode->i_sb;
        u16 min_order, max_order;

        max_order = EXT4_SB(sb)->s_max_folio_order;
        if (!max_order)
                return;

        min_order = EXT4_SB(sb)->s_min_folio_order;
        if (!min_order && !S_ISREG(inode->i_mode))
                return;

        if (ext4_test_inode_flag(inode, EXT4_INODE_JOURNAL_DATA))
                max_order = min_order;

        mapping_set_folio_order_range(inode->i_mapping, min_order, max_order);
}

struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
                          ext4_iget_flags flags, const char *function,
                          unsigned int line)
{
        struct ext4_iloc iloc;
        struct ext4_inode *raw_inode;
        struct ext4_inode_info *ei;
        struct ext4_super_block *es = EXT4_SB(sb)->s_es;
        struct inode *inode;
        journal_t *journal = EXT4_SB(sb)->s_journal;
        long ret;
        loff_t size;
        int block;
        uid_t i_uid;
        gid_t i_gid;
        projid_t i_projid;

        if ((!(flags & EXT4_IGET_SPECIAL) && is_special_ino(sb, ino)) ||
            (ino < EXT4_ROOT_INO) ||
            (ino > le32_to_cpu(es->s_inodes_count))) {
                if (flags & EXT4_IGET_HANDLE)
                        return ERR_PTR(-ESTALE);
                __ext4_error(sb, function, line, false, EFSCORRUPTED, 0,
                             "inode #%lu: comm %s: iget: illegal inode #",
                             ino, current->comm);
                return ERR_PTR(-EFSCORRUPTED);
        }

        inode = iget_locked(sb, ino);
        if (!inode)
                return ERR_PTR(-ENOMEM);
        if (!(inode_state_read_once(inode) & I_NEW)) {
                ret = check_igot_inode(inode, flags, function, line);
                if (ret) {
                        iput(inode);
                        return ERR_PTR(ret);
                }
                return inode;
        }

        ei = EXT4_I(inode);
        iloc.bh = NULL;

        ret = __ext4_get_inode_loc_noinmem(inode, &iloc);
        if (ret < 0)
                goto bad_inode;
        raw_inode = ext4_raw_inode(&iloc);

        if ((flags & EXT4_IGET_HANDLE) &&
            (raw_inode->i_links_count == 0) && (raw_inode->i_mode == 0)) {
                ret = -ESTALE;
                goto bad_inode;
        }

        if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
                ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
                if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
                        EXT4_INODE_SIZE(inode->i_sb) ||
                    (ei->i_extra_isize & 3)) {
                        ext4_error_inode(inode, function, line, 0,
                                         "iget: bad extra_isize %u "
                                         "(inode size %u)",
                                         ei->i_extra_isize,
                                         EXT4_INODE_SIZE(inode->i_sb));
                        ret = -EFSCORRUPTED;
                        goto bad_inode;
                }
        } else
                ei->i_extra_isize = 0;

        /* Precompute checksum seed for inode metadata */
        if (ext4_has_feature_metadata_csum(sb)) {
                struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
                __u32 csum;
                __le32 inum = cpu_to_le32(inode->i_ino);
                __le32 gen = raw_inode->i_generation;
                csum = ext4_chksum(sbi->s_csum_seed, (__u8 *)&inum,
                                   sizeof(inum));
                ei->i_csum_seed = ext4_chksum(csum, (__u8 *)&gen, sizeof(gen));
        }

        if ((!ext4_inode_csum_verify(inode, raw_inode, ei) ||
            ext4_simulate_fail(sb, EXT4_SIM_INODE_CRC)) &&
             (!(EXT4_SB(sb)->s_mount_state & EXT4_FC_REPLAY))) {
                ext4_error_inode_err(inode, function, line, 0,
                                EFSBADCRC, "iget: checksum invalid");
                ret = -EFSBADCRC;
                goto bad_inode;
        }

        inode->i_mode = le16_to_cpu(raw_inode->i_mode);
        i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
        i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
        if (ext4_has_feature_project(sb) &&
            EXT4_INODE_SIZE(sb) > EXT4_GOOD_OLD_INODE_SIZE &&
            EXT4_FITS_IN_INODE(raw_inode, ei, i_projid))
                i_projid = (projid_t)le32_to_cpu(raw_inode->i_projid);
        else
                i_projid = EXT4_DEF_PROJID;

        if (!(test_opt(inode->i_sb, NO_UID32))) {
                i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
                i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
        }
        i_uid_write(inode, i_uid);
        i_gid_write(inode, i_gid);
        ei->i_projid = make_kprojid(&init_user_ns, i_projid);
        set_nlink(inode, le16_to_cpu(raw_inode->i_links_count));

        ei->i_inline_off = 0;
        ei->i_dir_start_lookup = 0;
        ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
        /* We now have enough fields to check if the inode was active or not.
         * This is needed because nfsd might try to access dead inodes
         * the test is that same one that e2fsck uses
         * NeilBrown 1999oct15
         */
        if (inode->i_nlink == 0) {
                if ((inode->i_mode == 0 || flags & EXT4_IGET_SPECIAL ||
                     !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) &&
                    ino != EXT4_BOOT_LOADER_INO) {
                        /* this inode is deleted or unallocated */
                        if (flags & EXT4_IGET_SPECIAL) {
                                ext4_error_inode(inode, function, line, 0,
                                                 "iget: special inode unallocated");
                                ret = -EFSCORRUPTED;
                        } else
                                ret = -ESTALE;
                        goto bad_inode;
                }
                /* The only unlinked inodes we let through here have
                 * valid i_mode and are being read by the orphan
                 * recovery code: that's fine, we're about to complete
                 * the process of deleting those.
                 * OR it is the EXT4_BOOT_LOADER_INO which is
                 * not initialized on a new filesystem. */
        }
        ei->i_flags = le32_to_cpu(raw_inode->i_flags);
        ext4_set_inode_flags(inode, true);
        /* Detect invalid flag combination - can't have both inline data and extents */
        if (ext4_test_inode_flag(inode, EXT4_INODE_INLINE_DATA) &&
            ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
                ext4_error_inode(inode, function, line, 0,
                        "inode has both inline data and extents flags");
                ret = -EFSCORRUPTED;
                goto bad_inode;
        }
        inode->i_blocks = ext4_inode_blocks(raw_inode, ei);
        ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl_lo);
        if (ext4_has_feature_64bit(sb))
                ei->i_file_acl |=
                        ((__u64)le16_to_cpu(raw_inode->i_file_acl_high)) << 32;
        inode->i_size = ext4_isize(sb, raw_inode);
        size = i_size_read(inode);
        if (size < 0 || size > ext4_get_maxbytes(inode)) {
                ext4_error_inode(inode, function, line, 0,
                                 "iget: bad i_size value: %lld", size);
                ret = -EFSCORRUPTED;
                goto bad_inode;
        }
        /*
         * If dir_index is not enabled but there's dir with INDEX flag set,
         * we'd normally treat htree data as empty space. But with metadata
         * checksumming that corrupts checksums so forbid that.
         */
        if (!ext4_has_feature_dir_index(sb) &&
            ext4_has_feature_metadata_csum(sb) &&
            ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) {
                ext4_error_inode(inode, function, line, 0,
                         "iget: Dir with htree data on filesystem without dir_index feature.");
                ret = -EFSCORRUPTED;
                goto bad_inode;
        }
        ei->i_disksize = inode->i_size;
#ifdef CONFIG_QUOTA
        ei->i_reserved_quota = 0;
#endif
        inode->i_generation = le32_to_cpu(raw_inode->i_generation);
        ei->i_block_group = iloc.block_group;
        ei->i_last_alloc_group = ~0;
        /*
         * NOTE! The in-memory inode i_data array is in little-endian order
         * even on big-endian machines: we do NOT byteswap the block numbers!
         */
        for (block = 0; block < EXT4_N_BLOCKS; block++)
                ei->i_data[block] = raw_inode->i_block[block];
        INIT_LIST_HEAD(&ei->i_orphan);
        ext4_fc_init_inode(&ei->vfs_inode);

        /*
         * Set transaction id's of transactions that have to be committed
         * to finish f[data]sync. We set them to currently running transaction
         * as we cannot be sure that the inode or some of its metadata isn't
         * part of the transaction - the inode could have been reclaimed and
         * now it is reread from disk.
         */
        if (journal) {
                transaction_t *transaction;
                tid_t tid;

                read_lock(&journal->j_state_lock);
                if (journal->j_running_transaction)
                        transaction = journal->j_running_transaction;
                else
                        transaction = journal->j_committing_transaction;
                if (transaction)
                        tid = transaction->t_tid;
                else
                        tid = journal->j_commit_sequence;
                read_unlock(&journal->j_state_lock);
                ei->i_sync_tid = tid;
                ei->i_datasync_tid = tid;
        }

        if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
                if (ei->i_extra_isize == 0) {
                        /* The extra space is currently unused. Use it. */
                        BUILD_BUG_ON(sizeof(struct ext4_inode) & 3);
                        ei->i_extra_isize = sizeof(struct ext4_inode) -
                                            EXT4_GOOD_OLD_INODE_SIZE;
                } else {
                        ret = ext4_iget_extra_inode(inode, raw_inode, ei);
                        if (ret)
                                goto bad_inode;
                }
        }

        EXT4_INODE_GET_CTIME(inode, raw_inode);
        EXT4_INODE_GET_ATIME(inode, raw_inode);
        EXT4_INODE_GET_MTIME(inode, raw_inode);
        EXT4_EINODE_GET_XTIME(i_crtime, ei, raw_inode);

        if (likely(!test_opt2(inode->i_sb, HURD_COMPAT))) {
                u64 ivers = le32_to_cpu(raw_inode->i_disk_version);

                if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
                        if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
                                ivers |=
                    (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
                }
                ext4_inode_set_iversion_queried(inode, ivers);
        }

        ret = 0;
        if (ei->i_file_acl &&
            !ext4_inode_block_valid(inode, ei->i_file_acl, 1)) {
                ext4_error_inode(inode, function, line, 0,
                                 "iget: bad extended attribute block %llu",
                                 ei->i_file_acl);
                ret = -EFSCORRUPTED;
                goto bad_inode;
        } else if (!ext4_has_inline_data(inode)) {
                /* validate the block references in the inode */
                if (!(EXT4_SB(sb)->s_mount_state & EXT4_FC_REPLAY) &&
                        (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
                        (S_ISLNK(inode->i_mode) &&
                        !ext4_inode_is_fast_symlink(inode)))) {
                        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
                                ret = ext4_ext_check_inode(inode);
                        else
                                ret = ext4_ind_check_inode(inode);
                }
        }
        if (ret)
                goto bad_inode;

        if (S_ISREG(inode->i_mode)) {
                inode->i_op = &ext4_file_inode_operations;
                inode->i_fop = &ext4_file_operations;
                ext4_set_aops(inode);
        } else if (S_ISDIR(inode->i_mode)) {
                inode->i_op = &ext4_dir_inode_operations;
                inode->i_fop = &ext4_dir_operations;
        } else if (S_ISLNK(inode->i_mode)) {
                /* VFS does not allow setting these so must be corruption */
                if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) {
                        ext4_error_inode(inode, function, line, 0,
                                         "iget: immutable or append flags "
                                         "not allowed on symlinks");
                        ret = -EFSCORRUPTED;
                        goto bad_inode;
                }
                if (IS_ENCRYPTED(inode)) {
                        inode->i_op = &ext4_encrypted_symlink_inode_operations;
                } else if (ext4_inode_is_fast_symlink(inode)) {
                        inode->i_op = &ext4_fast_symlink_inode_operations;

                        /*
                         * Orphan cleanup can see inodes with i_size == 0
                         * and i_data uninitialized. Skip size checks in
                         * that case. This is safe because the first thing
                         * ext4_evict_inode() does for fast symlinks is
                         * clearing of i_data and i_size.
                         */
                        if ((EXT4_SB(sb)->s_mount_state & EXT4_ORPHAN_FS)) {
                                if (inode->i_nlink != 0) {
                                        ext4_error_inode(inode, function, line, 0,
                                                "invalid orphan symlink nlink %d",
                                                inode->i_nlink);
                                        ret = -EFSCORRUPTED;
                                        goto bad_inode;
                                }
                        } else {
                                if (inode->i_size == 0 ||
                                    inode->i_size >= sizeof(ei->i_data) ||
                                    strnlen((char *)ei->i_data, inode->i_size + 1) !=
                                                inode->i_size) {
                                        ext4_error_inode(inode, function, line, 0,
                                                "invalid fast symlink length %llu",
                                                (unsigned long long)inode->i_size);
                                        ret = -EFSCORRUPTED;
                                        goto bad_inode;
                                }
                                inode_set_cached_link(inode, (char *)ei->i_data,
                                                      inode->i_size);
                        }
                } else {
                        inode->i_op = &ext4_symlink_inode_operations;
                }
        } else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
              S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
                inode->i_op = &ext4_special_inode_operations;
                if (raw_inode->i_block[0])
                        init_special_inode(inode, inode->i_mode,
                           old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
                else
                        init_special_inode(inode, inode->i_mode,
                           new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
        } else if (ino == EXT4_BOOT_LOADER_INO) {
                make_bad_inode(inode);
        } else {
                ret = -EFSCORRUPTED;
                ext4_error_inode(inode, function, line, 0,
                                 "iget: bogus i_mode (%o)", inode->i_mode);
                goto bad_inode;
        }
        if (IS_CASEFOLDED(inode) && !ext4_has_feature_casefold(inode->i_sb)) {
                ext4_error_inode(inode, function, line, 0,
                                 "casefold flag without casefold feature");
                ret = -EFSCORRUPTED;
                goto bad_inode;
        }

        ext4_set_inode_mapping_order(inode);

        ret = check_igot_inode(inode, flags, function, line);
        /*
         * -ESTALE here means there is nothing inherently wrong with the inode,
         * it's just not an inode we can return for an fhandle lookup.
         */
        if (ret == -ESTALE) {
                brelse(iloc.bh);
                unlock_new_inode(inode);
                iput(inode);
                return ERR_PTR(-ESTALE);
        }
        if (ret)
                goto bad_inode;
        brelse(iloc.bh);
        /* Initialize the "no ACL's" state for the simple cases */
        if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR) && !ei->i_file_acl)
                cache_no_acl(inode);
        unlock_new_inode(inode);
        return inode;

bad_inode:
        brelse(iloc.bh);
        iget_failed(inode);
        return ERR_PTR(ret);
}

static void __ext4_update_other_inode_time(struct super_block *sb,
                                           unsigned long orig_ino,
                                           unsigned long ino,
                                           struct ext4_inode *raw_inode)
{
        struct inode *inode;

        inode = find_inode_by_ino_rcu(sb, ino);
        if (!inode)
                return;

        if (!inode_is_dirtytime_only(inode))
                return;

        spin_lock(&inode->i_lock);
        if (inode_is_dirtytime_only(inode)) {
                struct ext4_inode_info  *ei = EXT4_I(inode);

                inode_state_clear(inode, I_DIRTY_TIME);
                spin_unlock(&inode->i_lock);

                spin_lock(&ei->i_raw_lock);
                EXT4_INODE_SET_CTIME(inode, raw_inode);
                EXT4_INODE_SET_MTIME(inode, raw_inode);
                EXT4_INODE_SET_ATIME(inode, raw_inode);
                ext4_inode_csum_set(inode, raw_inode, ei);
                spin_unlock(&ei->i_raw_lock);
                trace_ext4_other_inode_update_time(inode, orig_ino);
                return;
        }
        spin_unlock(&inode->i_lock);
}

/*
 * Opportunistically update the other time fields for other inodes in
 * the same inode table block.
 */
static void ext4_update_other_inodes_time(struct super_block *sb,
                                          unsigned long orig_ino, char *buf)
{
        unsigned long ino;
        int i, inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
        int inode_size = EXT4_INODE_SIZE(sb);

        /*
         * Calculate the first inode in the inode table block.  Inode
         * numbers are one-based.  That is, the first inode in a block
         * (assuming 4k blocks and 256 byte inodes) is (n*16 + 1).
         */
        ino = ((orig_ino - 1) & ~(inodes_per_block - 1)) + 1;
        rcu_read_lock();
        for (i = 0; i < inodes_per_block; i++, ino++, buf += inode_size) {
                if (ino == orig_ino)
                        continue;
                __ext4_update_other_inode_time(sb, orig_ino, ino,
                                               (struct ext4_inode *)buf);
        }
        rcu_read_unlock();
}

/*
 * Post the struct inode info into an on-disk inode location in the
 * buffer-cache.  This gobbles the caller's reference to the
 * buffer_head in the inode location struct.
 *
 * The caller must have write access to iloc->bh.
 */
static int ext4_do_update_inode(handle_t *handle,
                                struct inode *inode,
                                struct ext4_iloc *iloc)
{
        struct ext4_inode *raw_inode = ext4_raw_inode(iloc);
        struct ext4_inode_info *ei = EXT4_I(inode);
        struct buffer_head *bh = iloc->bh;
        struct super_block *sb = inode->i_sb;
        int err;
        int need_datasync = 0, set_large_file = 0;

        spin_lock(&ei->i_raw_lock);

        /*
         * For fields not tracked in the in-memory inode, initialise them
         * to zero for new inodes.
         */
        if (ext4_test_inode_state(inode, EXT4_STATE_NEW))
                memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);

        if (READ_ONCE(ei->i_disksize) != ext4_isize(inode->i_sb, raw_inode))
                need_datasync = 1;
        if (ei->i_disksize > 0x7fffffffULL) {
                if (!ext4_has_feature_large_file(sb) ||
                    EXT4_SB(sb)->s_es->s_rev_level == cpu_to_le32(EXT4_GOOD_OLD_REV))
                        set_large_file = 1;
        }

        err = ext4_fill_raw_inode(inode, raw_inode);
        spin_unlock(&ei->i_raw_lock);
        if (err) {
                EXT4_ERROR_INODE(inode, "corrupted inode contents");
                goto out_brelse;
        }

        if (inode->i_sb->s_flags & SB_LAZYTIME)
                ext4_update_other_inodes_time(inode->i_sb, inode->i_ino,
                                              bh->b_data);

        BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
        err = ext4_handle_dirty_metadata(handle, NULL, bh);
        if (err)
                goto out_error;
        ext4_clear_inode_state(inode, EXT4_STATE_NEW);
        if (set_large_file) {
                BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get write access");
                err = ext4_journal_get_write_access(handle, sb,
                                                    EXT4_SB(sb)->s_sbh,
                                                    EXT4_JTR_NONE);
                if (err)
                        goto out_error;
                lock_buffer(EXT4_SB(sb)->s_sbh);
                ext4_set_feature_large_file(sb);
                ext4_superblock_csum_set(sb);
                unlock_buffer(EXT4_SB(sb)->s_sbh);
                ext4_handle_sync(handle);
                err = ext4_handle_dirty_metadata(handle, NULL,
                                                 EXT4_SB(sb)->s_sbh);
        }
        ext4_update_inode_fsync_trans(handle, inode, need_datasync);
out_error:
        ext4_std_error(inode->i_sb, err);
out_brelse:
        brelse(bh);
        return err;
}

/*
 * ext4_write_inode()
 *
 * We are called from a few places:
 *
 * - Within generic_file_aio_write() -> generic_write_sync() for O_SYNC files.
 *   Here, there will be no transaction running. We wait for any running
 *   transaction to commit.
 *
 * - Within flush work (sys_sync(), kupdate and such).
 *   We wait on commit, if told to.
 *
 * - Within iput_final() -> write_inode_now()
 *   We wait on commit, if told to.
 *
 * In all cases it is actually safe for us to return without doing anything,
 * because the inode has been copied into a raw inode buffer in
 * ext4_mark_inode_dirty().  This is a correctness thing for WB_SYNC_ALL
 * writeback.
 *
 * Note that we are absolutely dependent upon all inode dirtiers doing the
 * right thing: they *must* call mark_inode_dirty() after dirtying info in
 * which we are interested.
 *
 * It would be a bug for them to not do this.  The code:
 *
 *      mark_inode_dirty(inode)
 *      stuff();
 *      inode->i_size = expr;
 *
 * is in error because write_inode() could occur while `stuff()' is running,
 * and the new i_size will be lost.  Plus the inode will no longer be on the
 * superblock's dirty inode list.
 */
int ext4_write_inode(struct inode *inode, struct writeback_control *wbc)
{
        int err;

        if (WARN_ON_ONCE(current->flags & PF_MEMALLOC))
                return 0;

        err = ext4_emergency_state(inode->i_sb);
        if (unlikely(err))
                return err;

        if (EXT4_SB(inode->i_sb)->s_journal) {
                if (ext4_journal_current_handle()) {
                        ext4_debug("called recursively, non-PF_MEMALLOC!\n");
                        dump_stack();
                        return -EIO;
                }

                /*
                 * No need to force transaction in WB_SYNC_NONE mode. Also
                 * ext4_sync_fs() will force the commit after everything is
                 * written.
                 */
                if (wbc->sync_mode != WB_SYNC_ALL || wbc->for_sync)
                        return 0;

                err = ext4_fc_commit(EXT4_SB(inode->i_sb)->s_journal,
                                                EXT4_I(inode)->i_sync_tid);
        } else {
                struct ext4_iloc iloc;

                err = __ext4_get_inode_loc_noinmem(inode, &iloc);
                if (err)
                        return err;
                /*
                 * sync(2) will flush the whole buffer cache. No need to do
                 * it here separately for each inode.
                 */
                if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync)
                        sync_dirty_buffer(iloc.bh);
                if (buffer_req(iloc.bh) && !buffer_uptodate(iloc.bh)) {
                        ext4_error_inode_block(inode, iloc.bh->b_blocknr, EIO,
                                               "IO error syncing inode");
                        err = -EIO;
                }
                brelse(iloc.bh);
        }
        return err;
}

/*
 * In data=journal mode ext4_journalled_invalidate_folio() may fail to invalidate
 * buffers that are attached to a folio straddling i_size and are undergoing
 * commit. In that case we have to wait for commit to finish and try again.
 */
static void ext4_wait_for_tail_page_commit(struct inode *inode)
{
        unsigned offset;
        journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
        tid_t commit_tid;
        int ret;
        bool has_transaction;

        offset = inode->i_size & (PAGE_SIZE - 1);
        /*
         * If the folio is fully truncated, we don't need to wait for any commit
         * (and we even should not as __ext4_journalled_invalidate_folio() may
         * strip all buffers from the folio but keep the folio dirty which can then
         * confuse e.g. concurrent ext4_writepages() seeing dirty folio without
         * buffers). Also we don't need to wait for any commit if all buffers in
         * the folio remain valid. This is most beneficial for the common case of
         * blocksize == PAGESIZE.
         */
        if (!offset || offset > (PAGE_SIZE - i_blocksize(inode)))
                return;
        while (1) {
                struct folio *folio = filemap_lock_folio(inode->i_mapping,
                                      inode->i_size >> PAGE_SHIFT);
                if (IS_ERR(folio))
                        return;
                ret = __ext4_journalled_invalidate_folio(folio, offset,
                                                folio_size(folio) - offset);
                folio_unlock(folio);
                folio_put(folio);
                if (ret != -EBUSY)
                        return;
                has_transaction = false;
                read_lock(&journal->j_state_lock);
                if (journal->j_committing_transaction) {
                        commit_tid = journal->j_committing_transaction->t_tid;
                        has_transaction = true;
                }
                read_unlock(&journal->j_state_lock);
                if (has_transaction)
                        jbd2_log_wait_commit(journal, commit_tid);
        }
}

/*
 * ext4_setattr()
 *
 * Called from notify_change.
 *
 * We want to trap VFS attempts to truncate the file as soon as
 * possible.  In particular, we want to make sure that when the VFS
 * shrinks i_size, we put the inode on the orphan list and modify
 * i_disksize immediately, so that during the subsequent flushing of
 * dirty pages and freeing of disk blocks, we can guarantee that any
 * commit will leave the blocks being flushed in an unused state on
 * disk.  (On recovery, the inode will get truncated and the blocks will
 * be freed, so we have a strong guarantee that no future commit will
 * leave these blocks visible to the user.)
 *
 * Another thing we have to assure is that if we are in ordered mode
 * and inode is still attached to the committing transaction, we must
 * we start writeout of all the dirty pages which are being truncated.
 * This way we are sure that all the data written in the previous
 * transaction are already on disk (truncate waits for pages under
 * writeback).
 *
 * Called with inode->i_rwsem down.
 */
int ext4_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
                 struct iattr *attr)
{
        struct inode *inode = d_inode(dentry);
        int error, rc = 0;
        int orphan = 0;
        const unsigned int ia_valid = attr->ia_valid;
        bool inc_ivers = true;

        error = ext4_emergency_state(inode->i_sb);
        if (unlikely(error))
                return error;

        if (unlikely(IS_IMMUTABLE(inode)))
                return -EPERM;

        if (unlikely(IS_APPEND(inode) &&
                     (ia_valid & (ATTR_MODE | ATTR_UID |
                                  ATTR_GID | ATTR_TIMES_SET))))
                return -EPERM;

        error = setattr_prepare(idmap, dentry, attr);
        if (error)
                return error;

        error = fscrypt_prepare_setattr(dentry, attr);
        if (error)
                return error;

        if (is_quota_modification(idmap, inode, attr)) {
                error = dquot_initialize(inode);
                if (error)
                        return error;
        }

        if (i_uid_needs_update(idmap, attr, inode) ||
            i_gid_needs_update(idmap, attr, inode)) {
                handle_t *handle;

                /* (user+group)*(old+new) structure, inode write (sb,
                 * inode block, ? - but truncate inode update has it) */
                handle = ext4_journal_start(inode, EXT4_HT_QUOTA,
                        (EXT4_MAXQUOTAS_INIT_BLOCKS(inode->i_sb) +
                         EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb)) + 3);
                if (IS_ERR(handle)) {
                        error = PTR_ERR(handle);
                        goto err_out;
                }

                /* dquot_transfer() calls back ext4_get_inode_usage() which
                 * counts xattr inode references.
                 */
                down_read(&EXT4_I(inode)->xattr_sem);
                error = dquot_transfer(idmap, inode, attr);
                up_read(&EXT4_I(inode)->xattr_sem);

                if (error) {
                        ext4_journal_stop(handle);
                        return error;
                }
                /* Update corresponding info in inode so that everything is in
                 * one transaction */
                i_uid_update(idmap, attr, inode);
                i_gid_update(idmap, attr, inode);
                error = ext4_mark_inode_dirty(handle, inode);
                ext4_journal_stop(handle);
                if (unlikely(error)) {
                        return error;
                }
        }

        if (attr->ia_valid & ATTR_SIZE) {
                handle_t *handle;
                loff_t oldsize = inode->i_size;
                loff_t old_disksize;
                int shrink = (attr->ia_size < inode->i_size);

                if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
                        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);

                        if (attr->ia_size > sbi->s_bitmap_maxbytes) {
                                return -EFBIG;
                        }
                }
                if (!S_ISREG(inode->i_mode)) {
                        return -EINVAL;
                }

                if (attr->ia_size == inode->i_size)
                        inc_ivers = false;

                /*
                 * If file has inline data but new size exceeds inline capacity,
                 * convert to extent-based storage first to prevent inconsistent
                 * state (inline flag set but size exceeds inline capacity).
                 */
                if (ext4_has_inline_data(inode) &&
                    attr->ia_size > EXT4_I(inode)->i_inline_size) {
                        error = ext4_convert_inline_data(inode);
                        if (error)
                                goto err_out;
                }

                if (shrink) {
                        if (ext4_should_order_data(inode)) {
                                error = ext4_begin_ordered_truncate(inode,
                                                            attr->ia_size);
                                if (error)
                                        goto err_out;
                        }
                        /*
                         * Blocks are going to be removed from the inode. Wait
                         * for dio in flight.
                         */
                        inode_dio_wait(inode);
                }

                filemap_invalidate_lock(inode->i_mapping);

                rc = ext4_break_layouts(inode);
                if (rc) {
                        filemap_invalidate_unlock(inode->i_mapping);
                        goto err_out;
                }

                if (attr->ia_size != inode->i_size) {
                        /* attach jbd2 jinode for EOF folio tail zeroing */
                        if (attr->ia_size & (inode->i_sb->s_blocksize - 1) ||
                            oldsize & (inode->i_sb->s_blocksize - 1)) {
                                error = ext4_inode_attach_jinode(inode);
                                if (error)
                                        goto out_mmap_sem;
                        }

                        handle = ext4_journal_start(inode, EXT4_HT_INODE, 3);
                        if (IS_ERR(handle)) {
                                error = PTR_ERR(handle);
                                goto out_mmap_sem;
                        }
                        if (ext4_handle_valid(handle) && shrink) {
                                error = ext4_orphan_add(handle, inode);
                                orphan = 1;
                        }
                        /*
                         * Update c/mtime and tail zero the EOF folio on
                         * truncate up. ext4_truncate() handles the shrink case
                         * below.
                         */
                        if (!shrink) {
                                inode_set_mtime_to_ts(inode,
                                                      inode_set_ctime_current(inode));
                                if (oldsize & (inode->i_sb->s_blocksize - 1))
                                        ext4_block_truncate_page(handle,
                                                        inode->i_mapping, oldsize);
                        }

                        if (shrink)
                                ext4_fc_track_range(handle, inode,
                                        (attr->ia_size > 0 ? attr->ia_size - 1 : 0) >>
                                        inode->i_sb->s_blocksize_bits,
                                        EXT_MAX_BLOCKS - 1);
                        else
                                ext4_fc_track_range(
                                        handle, inode,
                                        (oldsize > 0 ? oldsize - 1 : oldsize) >>
                                        inode->i_sb->s_blocksize_bits,
                                        (attr->ia_size > 0 ? attr->ia_size - 1 : 0) >>
                                        inode->i_sb->s_blocksize_bits);

                        down_write(&EXT4_I(inode)->i_data_sem);
                        old_disksize = EXT4_I(inode)->i_disksize;
                        EXT4_I(inode)->i_disksize = attr->ia_size;

                        /*
                         * We have to update i_size under i_data_sem together
                         * with i_disksize to avoid races with writeback code
                         * running ext4_wb_update_i_disksize().
                         */
                        if (!error)
                                i_size_write(inode, attr->ia_size);
                        else
                                EXT4_I(inode)->i_disksize = old_disksize;
                        up_write(&EXT4_I(inode)->i_data_sem);
                        rc = ext4_mark_inode_dirty(handle, inode);
                        if (!error)
                                error = rc;
                        ext4_journal_stop(handle);
                        if (error)
                                goto out_mmap_sem;
                        if (!shrink) {
                                pagecache_isize_extended(inode, oldsize,
                                                         inode->i_size);
                        } else if (ext4_should_journal_data(inode)) {
                                ext4_wait_for_tail_page_commit(inode);
                        }
                }

                /*
                 * Truncate pagecache after we've waited for commit
                 * in data=journal mode to make pages freeable.
                 */
                truncate_pagecache(inode, inode->i_size);
                /*
                 * Call ext4_truncate() even if i_size didn't change to
                 * truncate possible preallocated blocks.
                 */
                if (attr->ia_size <= oldsize) {
                        rc = ext4_truncate(inode);
                        if (rc)
                                error = rc;
                }
out_mmap_sem:
                filemap_invalidate_unlock(inode->i_mapping);
        }

        if (!error) {
                if (inc_ivers)
                        inode_inc_iversion(inode);
                setattr_copy(idmap, inode, attr);
                mark_inode_dirty(inode);
        }

        /*
         * If the call to ext4_truncate failed to get a transaction handle at
         * all, we need to clean up the in-core orphan list manually.
         */
        if (orphan && inode->i_nlink)
                ext4_orphan_del(NULL, inode);

        if (!error && (ia_valid & ATTR_MODE))
                rc = posix_acl_chmod(idmap, dentry, inode->i_mode);

err_out:
        if  (error)
                ext4_std_error(inode->i_sb, error);
        if (!error)
                error = rc;
        return error;
}

u32 ext4_dio_alignment(struct inode *inode)
{
        if (fsverity_active(inode))
                return 0;
        if (ext4_should_journal_data(inode))
                return 0;
        if (ext4_has_inline_data(inode))
                return 0;
        if (IS_ENCRYPTED(inode)) {
                if (!fscrypt_dio_supported(inode))
                        return 0;
                return i_blocksize(inode);
        }
        return 1; /* use the iomap defaults */
}

int ext4_getattr(struct mnt_idmap *idmap, const struct path *path,
                 struct kstat *stat, u32 request_mask, unsigned int query_flags)
{
        struct inode *inode = d_inode(path->dentry);
        struct ext4_inode *raw_inode;
        struct ext4_inode_info *ei = EXT4_I(inode);
        unsigned int flags;

        if ((request_mask & STATX_BTIME) &&
            EXT4_FITS_IN_INODE(raw_inode, ei, i_crtime)) {
                stat->result_mask |= STATX_BTIME;
                stat->btime.tv_sec = ei->i_crtime.tv_sec;
                stat->btime.tv_nsec = ei->i_crtime.tv_nsec;
        }

        /*
         * Return the DIO alignment restrictions if requested.  We only return
         * this information when requested, since on encrypted files it might
         * take a fair bit of work to get if the file wasn't opened recently.
         */
        if ((request_mask & STATX_DIOALIGN) && S_ISREG(inode->i_mode)) {
                u32 dio_align = ext4_dio_alignment(inode);

                stat->result_mask |= STATX_DIOALIGN;
                if (dio_align == 1) {
                        struct block_device *bdev = inode->i_sb->s_bdev;

                        /* iomap defaults */
                        stat->dio_mem_align = bdev_dma_alignment(bdev) + 1;
                        stat->dio_offset_align = bdev_logical_block_size(bdev);
                } else {
                        stat->dio_mem_align = dio_align;
                        stat->dio_offset_align = dio_align;
                }
        }

        if ((request_mask & STATX_WRITE_ATOMIC) && S_ISREG(inode->i_mode)) {
                struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
                unsigned int awu_min = 0, awu_max = 0;

                if (ext4_inode_can_atomic_write(inode)) {
                        awu_min = sbi->s_awu_min;
                        awu_max = sbi->s_awu_max;
                }

                generic_fill_statx_atomic_writes(stat, awu_min, awu_max, 0);
        }

        flags = ei->i_flags & EXT4_FL_USER_VISIBLE;
        if (flags & EXT4_APPEND_FL)
                stat->attributes |= STATX_ATTR_APPEND;
        if (flags & EXT4_COMPR_FL)
                stat->attributes |= STATX_ATTR_COMPRESSED;
        if (flags & EXT4_ENCRYPT_FL)
                stat->attributes |= STATX_ATTR_ENCRYPTED;
        if (flags & EXT4_IMMUTABLE_FL)
                stat->attributes |= STATX_ATTR_IMMUTABLE;
        if (flags & EXT4_NODUMP_FL)
                stat->attributes |= STATX_ATTR_NODUMP;
        if (flags & EXT4_VERITY_FL)
                stat->attributes |= STATX_ATTR_VERITY;

        stat->attributes_mask |= (STATX_ATTR_APPEND |
                                  STATX_ATTR_COMPRESSED |
                                  STATX_ATTR_ENCRYPTED |
                                  STATX_ATTR_IMMUTABLE |
                                  STATX_ATTR_NODUMP |
                                  STATX_ATTR_VERITY);

        generic_fillattr(idmap, request_mask, inode, stat);
        return 0;
}

int ext4_file_getattr(struct mnt_idmap *idmap,
                      const struct path *path, struct kstat *stat,
                      u32 request_mask, unsigned int query_flags)
{
        struct inode *inode = d_inode(path->dentry);
        u64 delalloc_blocks;

        ext4_getattr(idmap, path, stat, request_mask, query_flags);

        /*
         * If there is inline data in the inode, the inode will normally not
         * have data blocks allocated (it may have an external xattr block).
         * Report at least one sector for such files, so tools like tar, rsync,
         * others don't incorrectly think the file is completely sparse.
         */
        if (unlikely(ext4_has_inline_data(inode)))
                stat->blocks += (stat->size + 511) >> 9;

        /*
         * We can't update i_blocks if the block allocation is delayed
         * otherwise in the case of system crash before the real block
         * allocation is done, we will have i_blocks inconsistent with
         * on-disk file blocks.
         * We always keep i_blocks updated together with real
         * allocation. But to not confuse with user, stat
         * will return the blocks that include the delayed allocation
         * blocks for this file.
         */
        delalloc_blocks = EXT4_C2B(EXT4_SB(inode->i_sb),
                                   EXT4_I(inode)->i_reserved_data_blocks);
        stat->blocks += delalloc_blocks << (inode->i_sb->s_blocksize_bits - 9);
        return 0;
}

static int ext4_index_trans_blocks(struct inode *inode, int lblocks,
                                   int pextents)
{
        if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
                return ext4_ind_trans_blocks(inode, lblocks);
        return ext4_ext_index_trans_blocks(inode, pextents);
}

/*
 * Account for index blocks, block groups bitmaps and block group
 * descriptor blocks if modify datablocks and index blocks
 * worse case, the indexs blocks spread over different block groups
 *
 * If datablocks are discontiguous, they are possible to spread over
 * different block groups too. If they are contiguous, with flexbg,
 * they could still across block group boundary.
 *
 * Also account for superblock, inode, quota and xattr blocks
 */
int ext4_meta_trans_blocks(struct inode *inode, int lblocks, int pextents)
{
        ext4_group_t groups, ngroups = ext4_get_groups_count(inode->i_sb);
        int gdpblocks;
        int idxblocks;
        int ret;

        /*
         * How many index and leaf blocks need to touch to map @lblocks
         * logical blocks to @pextents physical extents?
         */
        idxblocks = ext4_index_trans_blocks(inode, lblocks, pextents);

        /*
         * Now let's see how many group bitmaps and group descriptors need
         * to account
         */
        groups = idxblocks + pextents;
        gdpblocks = groups;
        if (groups > ngroups)
                groups = ngroups;
        if (groups > EXT4_SB(inode->i_sb)->s_gdb_count)
                gdpblocks = EXT4_SB(inode->i_sb)->s_gdb_count;

        /* bitmaps and block group descriptor blocks */
        ret = idxblocks + groups + gdpblocks;

        /* Blocks for super block, inode, quota and xattr blocks */
        ret += EXT4_META_TRANS_BLOCKS(inode->i_sb);

        return ret;
}

/*
 * Calculate the journal credits for modifying the number of blocks
 * in a single extent within one transaction. 'nrblocks' is used only
 * for non-extent inodes. For extent type inodes, 'nrblocks' can be
 * zero if the exact number of blocks is unknown.
 */
int ext4_chunk_trans_extent(struct inode *inode, int nrblocks)
{
        int ret;

        ret = ext4_meta_trans_blocks(inode, nrblocks, 1);
        /* Account for data blocks for journalled mode */
        if (ext4_should_journal_data(inode))
                ret += nrblocks;
        return ret;
}

/*
 * Calculate the journal credits for a chunk of data modification.
 *
 * This is called from DIO, fallocate or whoever calling
 * ext4_map_blocks() to map/allocate a chunk of contiguous disk blocks.
 *
 * journal buffers for data blocks are not included here, as DIO
 * and fallocate do no need to journal data buffers.
 */
int ext4_chunk_trans_blocks(struct inode *inode, int nrblocks)
{
        return ext4_meta_trans_blocks(inode, nrblocks, 1);
}

/*
 * The caller must have previously called ext4_reserve_inode_write().
 * Give this, we know that the caller already has write access to iloc->bh.
 */
int ext4_mark_iloc_dirty(handle_t *handle,
                         struct inode *inode, struct ext4_iloc *iloc)
{
        int err = 0;

        err = ext4_emergency_state(inode->i_sb);
        if (unlikely(err)) {
                put_bh(iloc->bh);
                return err;
        }
        ext4_fc_track_inode(handle, inode);

        /* the do_update_inode consumes one bh->b_count */
        get_bh(iloc->bh);

        /* ext4_do_update_inode() does jbd2_journal_dirty_metadata */
        err = ext4_do_update_inode(handle, inode, iloc);
        put_bh(iloc->bh);
        return err;
}

/*
 * On success, We end up with an outstanding reference count against
 * iloc->bh.  This _must_ be cleaned up later.
 */

int
ext4_reserve_inode_write(handle_t *handle, struct inode *inode,
                         struct ext4_iloc *iloc)
{
        int err;

        err = ext4_emergency_state(inode->i_sb);
        if (unlikely(err))
                return err;

        err = ext4_get_inode_loc(inode, iloc);
        if (!err) {
                BUFFER_TRACE(iloc->bh, "get_write_access");
                err = ext4_journal_get_write_access(handle, inode->i_sb,
                                                    iloc->bh, EXT4_JTR_NONE);
                if (err) {
                        brelse(iloc->bh);
                        iloc->bh = NULL;
                }
                ext4_fc_track_inode(handle, inode);
        }
        ext4_std_error(inode->i_sb, err);
        return err;
}

static int __ext4_expand_extra_isize(struct inode *inode,
                                     unsigned int new_extra_isize,
                                     struct ext4_iloc *iloc,
                                     handle_t *handle, int *no_expand)
{
        struct ext4_inode *raw_inode;
        struct ext4_xattr_ibody_header *header;
        unsigned int inode_size = EXT4_INODE_SIZE(inode->i_sb);
        struct ext4_inode_info *ei = EXT4_I(inode);
        int error;

        /* this was checked at iget time, but double check for good measure */
        if ((EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize > inode_size) ||
            (ei->i_extra_isize & 3)) {
                EXT4_ERROR_INODE(inode, "bad extra_isize %u (inode size %u)",
                                 ei->i_extra_isize,
                                 EXT4_INODE_SIZE(inode->i_sb));
                return -EFSCORRUPTED;
        }
        if ((new_extra_isize < ei->i_extra_isize) ||
            (new_extra_isize < 4) ||
            (new_extra_isize > inode_size - EXT4_GOOD_OLD_INODE_SIZE))
                return -EINVAL; /* Should never happen */

        raw_inode = ext4_raw_inode(iloc);

        header = IHDR(inode, raw_inode);

        /* No extended attributes present */
        if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR) ||
            header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)) {
                memset((void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE +
                       EXT4_I(inode)->i_extra_isize, 0,
                       new_extra_isize - EXT4_I(inode)->i_extra_isize);
                EXT4_I(inode)->i_extra_isize = new_extra_isize;
                return 0;
        }

        /*
         * We may need to allocate external xattr block so we need quotas
         * initialized. Here we can be called with various locks held so we
         * cannot affort to initialize quotas ourselves. So just bail.
         */
        if (dquot_initialize_needed(inode))
                return -EAGAIN;

        /* try to expand with EAs present */
        error = ext4_expand_extra_isize_ea(inode, new_extra_isize,
                                           raw_inode, handle);
        if (error) {
                /*
                 * Inode size expansion failed; don't try again
                 */
                *no_expand = 1;
        }

        return error;
}

/*
 * Expand an inode by new_extra_isize bytes.
 * Returns 0 on success or negative error number on failure.
 */
static int ext4_try_to_expand_extra_isize(struct inode *inode,
                                          unsigned int new_extra_isize,
                                          struct ext4_iloc iloc,
                                          handle_t *handle)
{
        int no_expand;
        int error;

        if (ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND))
                return -EOVERFLOW;

        /*
         * In nojournal mode, we can immediately attempt to expand
         * the inode.  When journaled, we first need to obtain extra
         * buffer credits since we may write into the EA block
         * with this same handle. If journal_extend fails, then it will
         * only result in a minor loss of functionality for that inode.
         * If this is felt to be critical, then e2fsck should be run to
         * force a large enough s_min_extra_isize.
         */
        if (ext4_journal_extend(handle,
                                EXT4_DATA_TRANS_BLOCKS(inode->i_sb), 0) != 0)
                return -ENOSPC;

        if (ext4_write_trylock_xattr(inode, &no_expand) == 0)
                return -EBUSY;

        error = __ext4_expand_extra_isize(inode, new_extra_isize, &iloc,
                                          handle, &no_expand);
        ext4_write_unlock_xattr(inode, &no_expand);

        return error;
}

int ext4_expand_extra_isize(struct inode *inode,
                            unsigned int new_extra_isize,
                            struct ext4_iloc *iloc)
{
        handle_t *handle;
        int no_expand;
        int error, rc;

        if (ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND)) {
                brelse(iloc->bh);
                return -EOVERFLOW;
        }

        handle = ext4_journal_start(inode, EXT4_HT_INODE,
                                    EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
        if (IS_ERR(handle)) {
                error = PTR_ERR(handle);
                brelse(iloc->bh);
                return error;
        }

        ext4_write_lock_xattr(inode, &no_expand);

        BUFFER_TRACE(iloc->bh, "get_write_access");
        error = ext4_journal_get_write_access(handle, inode->i_sb, iloc->bh,
                                              EXT4_JTR_NONE);
        if (error) {
                brelse(iloc->bh);
                goto out_unlock;
        }

        error = __ext4_expand_extra_isize(inode, new_extra_isize, iloc,
                                          handle, &no_expand);

        rc = ext4_mark_iloc_dirty(handle, inode, iloc);
        if (!error)
                error = rc;

out_unlock:
        ext4_write_unlock_xattr(inode, &no_expand);
        ext4_journal_stop(handle);
        return error;
}

/*
 * What we do here is to mark the in-core inode as clean with respect to inode
 * dirtiness (it may still be data-dirty).
 * This means that the in-core inode may be reaped by prune_icache
 * without having to perform any I/O.  This is a very good thing,
 * because *any* task may call prune_icache - even ones which
 * have a transaction open against a different journal.
 *
 * Is this cheating?  Not really.  Sure, we haven't written the
 * inode out, but prune_icache isn't a user-visible syncing function.
 * Whenever the user wants stuff synced (sys_sync, sys_msync, sys_fsync)
 * we start and wait on commits.
 */
int __ext4_mark_inode_dirty(handle_t *handle, struct inode *inode,
                                const char *func, unsigned int line)
{
        struct ext4_iloc iloc;
        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
        int err;

        might_sleep();
        trace_ext4_mark_inode_dirty(inode, _RET_IP_);
        err = ext4_reserve_inode_write(handle, inode, &iloc);
        if (err)
                goto out;

        if (EXT4_I(inode)->i_extra_isize < sbi->s_want_extra_isize)
                ext4_try_to_expand_extra_isize(inode, sbi->s_want_extra_isize,
                                               iloc, handle);

        err = ext4_mark_iloc_dirty(handle, inode, &iloc);
out:
        if (unlikely(err))
                ext4_error_inode_err(inode, func, line, 0, err,
                                        "mark_inode_dirty error");
        return err;
}

/*
 * ext4_dirty_inode() is called from __mark_inode_dirty()
 *
 * We're really interested in the case where a file is being extended.
 * i_size has been changed by generic_commit_write() and we thus need
 * to include the updated inode in the current transaction.
 *
 * Also, dquot_alloc_block() will always dirty the inode when blocks
 * are allocated to the file.
 *
 * If the inode is marked synchronous, we don't honour that here - doing
 * so would cause a commit on atime updates, which we don't bother doing.
 * We handle synchronous inodes at the highest possible level.
 */
void ext4_dirty_inode(struct inode *inode, int flags)
{
        handle_t *handle;

        handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
        if (IS_ERR(handle))
                return;
        ext4_mark_inode_dirty(handle, inode);
        ext4_journal_stop(handle);
}

int ext4_change_inode_journal_flag(struct inode *inode, int val)
{
        journal_t *journal;
        handle_t *handle;
        int err;
        int alloc_ctx;

        /*
         * We have to be very careful here: changing a data block's
         * journaling status dynamically is dangerous.  If we write a
         * data block to the journal, change the status and then delete
         * that block, we risk forgetting to revoke the old log record
         * from the journal and so a subsequent replay can corrupt data.
         * So, first we make sure that the journal is empty and that
         * nobody is changing anything.
         */

        journal = EXT4_JOURNAL(inode);
        if (!journal)
                return 0;
        if (is_journal_aborted(journal))
                return -EROFS;

        /* Wait for all existing dio workers */
        inode_dio_wait(inode);

        /*
         * Before flushing the journal and switching inode's aops, we have
         * to flush all dirty data the inode has. There can be outstanding
         * delayed allocations, there can be unwritten extents created by
         * fallocate or buffered writes in dioread_nolock mode covered by
         * dirty data which can be converted only after flushing the dirty
         * data (and journalled aops don't know how to handle these cases).
         */
        filemap_invalidate_lock(inode->i_mapping);
        err = filemap_write_and_wait(inode->i_mapping);
        if (err < 0) {
                filemap_invalidate_unlock(inode->i_mapping);
                return err;
        }
        /* Before switch the inode journalling mode evict all the page cache. */
        truncate_pagecache(inode, 0);

        alloc_ctx = ext4_writepages_down_write(inode->i_sb);
        jbd2_journal_lock_updates(journal);

        /*
         * OK, there are no updates running now, and all cached data is
         * synced to disk.  We are now in a completely consistent state
         * which doesn't have anything in the journal, and we know that
         * no filesystem updates are running, so it is safe to modify
         * the inode's in-core data-journaling state flag now.
         */

        if (val)
                ext4_set_inode_flag(inode, EXT4_INODE_JOURNAL_DATA);
        else {
                err = jbd2_journal_flush(journal, 0);
                if (err < 0) {
                        jbd2_journal_unlock_updates(journal);
                        ext4_writepages_up_write(inode->i_sb, alloc_ctx);
                        filemap_invalidate_unlock(inode->i_mapping);
                        return err;
                }
                ext4_clear_inode_flag(inode, EXT4_INODE_JOURNAL_DATA);
        }
        ext4_set_aops(inode);
        ext4_set_inode_mapping_order(inode);

        jbd2_journal_unlock_updates(journal);
        ext4_writepages_up_write(inode->i_sb, alloc_ctx);
        filemap_invalidate_unlock(inode->i_mapping);

        /* Finally we can mark the inode as dirty. */

        handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
        if (IS_ERR(handle))
                return PTR_ERR(handle);

        ext4_fc_mark_ineligible(inode->i_sb,
                EXT4_FC_REASON_JOURNAL_FLAG_CHANGE, handle);
        err = ext4_mark_inode_dirty(handle, inode);
        ext4_handle_sync(handle);
        ext4_journal_stop(handle);
        ext4_std_error(inode->i_sb, err);

        return err;
}

static int ext4_bh_unmapped(handle_t *handle, struct inode *inode,
                            struct buffer_head *bh)
{
        return !buffer_mapped(bh);
}

static int ext4_block_page_mkwrite(struct inode *inode, struct folio *folio,
                                   get_block_t get_block)
{
        handle_t *handle;
        loff_t size;
        unsigned long len;
        int credits;
        int ret;

        credits = ext4_chunk_trans_extent(inode,
                        ext4_journal_blocks_per_folio(inode));
        handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, credits);
        if (IS_ERR(handle))
                return PTR_ERR(handle);

        folio_lock(folio);
        size = i_size_read(inode);
        /* Page got truncated from under us? */
        if (folio->mapping != inode->i_mapping || folio_pos(folio) > size) {
                ret = -EFAULT;
                goto out_error;
        }

        len = folio_size(folio);
        if (folio_pos(folio) + len > size)
                len = size - folio_pos(folio);

        ret = ext4_block_write_begin(handle, folio, 0, len, get_block);
        if (ret)
                goto out_error;

        if (!ext4_should_journal_data(inode)) {
                block_commit_write(folio, 0, len);
                folio_mark_dirty(folio);
        } else {
                ret = ext4_journal_folio_buffers(handle, folio, len);
                if (ret)
                        goto out_error;
        }
        ext4_journal_stop(handle);
        folio_wait_stable(folio);
        return ret;

out_error:
        folio_unlock(folio);
        ext4_journal_stop(handle);
        return ret;
}

vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf)
{
        struct vm_area_struct *vma = vmf->vma;
        struct folio *folio = page_folio(vmf->page);
        loff_t size;
        unsigned long len;
        int err;
        vm_fault_t ret;
        struct file *file = vma->vm_file;
        struct inode *inode = file_inode(file);
        struct address_space *mapping = inode->i_mapping;
        get_block_t *get_block = ext4_get_block;
        int retries = 0;

        if (unlikely(IS_IMMUTABLE(inode)))
                return VM_FAULT_SIGBUS;

        sb_start_pagefault(inode->i_sb);
        file_update_time(vma->vm_file);

        filemap_invalidate_lock_shared(mapping);

        err = ext4_convert_inline_data(inode);
        if (err)
                goto out_ret;

        /*
         * On data journalling we skip straight to the transaction handle:
         * there's no delalloc; page truncated will be checked later; the
         * early return w/ all buffers mapped (calculates size/len) can't
         * be used; and there's no dioread_nolock, so only ext4_get_block.
         */
        if (ext4_should_journal_data(inode))
                goto retry_alloc;

        /* Delalloc case is easy... */
        if (test_opt(inode->i_sb, DELALLOC) &&
            !ext4_nonda_switch(inode->i_sb)) {
                do {
                        err = block_page_mkwrite(vma, vmf,
                                                   ext4_da_get_block_prep);
                } while (err == -ENOSPC &&
                       ext4_should_retry_alloc(inode->i_sb, &retries));
                goto out_ret;
        }

        folio_lock(folio);
        size = i_size_read(inode);
        /* Page got truncated from under us? */
        if (folio->mapping != mapping || folio_pos(folio) > size) {
                folio_unlock(folio);
                ret = VM_FAULT_NOPAGE;
                goto out;
        }

        len = folio_size(folio);
        if (folio_pos(folio) + len > size)
                len = size - folio_pos(folio);
        /*
         * Return if we have all the buffers mapped. This avoids the need to do
         * journal_start/journal_stop which can block and take a long time
         *
         * This cannot be done for data journalling, as we have to add the
         * inode to the transaction's list to writeprotect pages on commit.
         */
        if (folio_buffers(folio)) {
                if (!ext4_walk_page_buffers(NULL, inode, folio_buffers(folio),
                                            0, len, NULL,
                                            ext4_bh_unmapped)) {
                        /* Wait so that we don't change page under IO */
                        folio_wait_stable(folio);
                        ret = VM_FAULT_LOCKED;
                        goto out;
                }
        }
        folio_unlock(folio);
        /* OK, we need to fill the hole... */
        if (ext4_should_dioread_nolock(inode))
                get_block = ext4_get_block_unwritten;
retry_alloc:
        /* Start journal and allocate blocks */
        err = ext4_block_page_mkwrite(inode, folio, get_block);
        if (err == -EAGAIN ||
            (err == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)))
                goto retry_alloc;
out_ret:
        ret = vmf_fs_error(err);
out:
        filemap_invalidate_unlock_shared(mapping);
        sb_end_pagefault(inode->i_sb);
        return ret;
}