// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2007 Oracle.  All rights reserved.
 */

#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/writeback.h>
#include <linux/sched/mm.h>
#include "messages.h"
#include "misc.h"
#include "ctree.h"
#include "transaction.h"
#include "btrfs_inode.h"
#include "extent_io.h"
#include "disk-io.h"
#include "compression.h"
#include "delalloc-space.h"
#include "qgroup.h"
#include "subpage.h"
#include "file.h"
#include "block-group.h"

static struct kmem_cache *btrfs_ordered_extent_cache;

static u64 entry_end(struct btrfs_ordered_extent *entry)
{
        if (entry->file_offset + entry->num_bytes < entry->file_offset)
                return (u64)-1;
        return entry->file_offset + entry->num_bytes;
}

/* returns NULL if the insertion worked, or it returns the node it did find
 * in the tree
 */
static struct rb_node *tree_insert(struct rb_root *root, u64 file_offset,
                                   struct rb_node *node)
{
        struct rb_node **p = &root->rb_node;
        struct rb_node *parent = NULL;
        struct btrfs_ordered_extent *entry;

        while (*p) {
                parent = *p;
                entry = rb_entry(parent, struct btrfs_ordered_extent, rb_node);

                if (file_offset < entry->file_offset)
                        p = &(*p)->rb_left;
                else if (file_offset >= entry_end(entry))
                        p = &(*p)->rb_right;
                else
                        return parent;
        }

        rb_link_node(node, parent, p);
        rb_insert_color(node, root);
        return NULL;
}

/*
 * look for a given offset in the tree, and if it can't be found return the
 * first lesser offset
 */
static struct rb_node *__tree_search(struct rb_root *root, u64 file_offset,
                                     struct rb_node **prev_ret)
{
        struct rb_node *n = root->rb_node;
        struct rb_node *prev = NULL;
        struct rb_node *test;
        struct btrfs_ordered_extent *entry;
        struct btrfs_ordered_extent *prev_entry = NULL;

        while (n) {
                entry = rb_entry(n, struct btrfs_ordered_extent, rb_node);
                prev = n;
                prev_entry = entry;

                if (file_offset < entry->file_offset)
                        n = n->rb_left;
                else if (file_offset >= entry_end(entry))
                        n = n->rb_right;
                else
                        return n;
        }
        if (!prev_ret)
                return NULL;

        while (prev && file_offset >= entry_end(prev_entry)) {
                test = rb_next(prev);
                if (!test)
                        break;
                prev_entry = rb_entry(test, struct btrfs_ordered_extent,
                                      rb_node);
                if (file_offset < entry_end(prev_entry))
                        break;

                prev = test;
        }
        if (prev)
                prev_entry = rb_entry(prev, struct btrfs_ordered_extent,
                                      rb_node);
        while (prev && file_offset < entry_end(prev_entry)) {
                test = rb_prev(prev);
                if (!test)
                        break;
                prev_entry = rb_entry(test, struct btrfs_ordered_extent,
                                      rb_node);
                prev = test;
        }
        *prev_ret = prev;
        return NULL;
}

static int btrfs_range_overlaps(struct btrfs_ordered_extent *entry, u64 file_offset,
                                u64 len)
{
        if (file_offset + len <= entry->file_offset ||
            entry->file_offset + entry->num_bytes <= file_offset)
                return 0;
        return 1;
}

/*
 * look find the first ordered struct that has this offset, otherwise
 * the first one less than this offset
 */
static inline struct rb_node *ordered_tree_search(struct btrfs_inode *inode,
                                                  u64 file_offset)
{
        struct rb_node *prev = NULL;
        struct rb_node *ret;
        struct btrfs_ordered_extent *entry;

        if (inode->ordered_tree_last) {
                entry = rb_entry(inode->ordered_tree_last, struct btrfs_ordered_extent,
                                 rb_node);
                if (in_range(file_offset, entry->file_offset, entry->num_bytes))
                        return inode->ordered_tree_last;
        }
        ret = __tree_search(&inode->ordered_tree, file_offset, &prev);
        if (!ret)
                ret = prev;
        if (ret)
                inode->ordered_tree_last = ret;
        return ret;
}

static struct btrfs_ordered_extent *alloc_ordered_extent(
                        struct btrfs_inode *inode, u64 file_offset, u64 num_bytes,
                        u64 ram_bytes, u64 disk_bytenr, u64 disk_num_bytes,
                        u64 offset, unsigned long flags, int compress_type)
{
        struct btrfs_ordered_extent *entry;
        int ret;
        u64 qgroup_rsv = 0;
        const bool is_nocow = (flags &
               ((1U << BTRFS_ORDERED_NOCOW) | (1U << BTRFS_ORDERED_PREALLOC)));

        /*
         * For a NOCOW write we can free the qgroup reserve right now. For a COW
         * one we transfer the reserved space from the inode's iotree into the
         * ordered extent by calling btrfs_qgroup_release_data() and tracking
         * the qgroup reserved amount in the ordered extent, so that later after
         * completing the ordered extent, when running the data delayed ref it
         * creates, we free the reserved data with btrfs_qgroup_free_refroot().
         */
        if (is_nocow)
                ret = btrfs_qgroup_free_data(inode, NULL, file_offset, num_bytes, &qgroup_rsv);
        else
                ret = btrfs_qgroup_release_data(inode, file_offset, num_bytes, &qgroup_rsv);

        if (ret < 0)
                return ERR_PTR(ret);

        entry = kmem_cache_zalloc(btrfs_ordered_extent_cache, GFP_NOFS);
        if (!entry) {
                entry = ERR_PTR(-ENOMEM);
                goto out;
        }

        entry->file_offset = file_offset;
        entry->num_bytes = num_bytes;
        entry->ram_bytes = ram_bytes;
        entry->disk_bytenr = disk_bytenr;
        entry->disk_num_bytes = disk_num_bytes;
        entry->offset = offset;
        entry->bytes_left = num_bytes;
        if (WARN_ON_ONCE(!igrab(&inode->vfs_inode))) {
                kmem_cache_free(btrfs_ordered_extent_cache, entry);
                entry = ERR_PTR(-ESTALE);
                goto out;
        }
        entry->inode = inode;
        entry->compress_type = compress_type;
        entry->truncated_len = (u64)-1;
        entry->qgroup_rsv = qgroup_rsv;
        entry->flags = flags;
        refcount_set(&entry->refs, 1);
        init_waitqueue_head(&entry->wait);
        INIT_LIST_HEAD(&entry->list);
        INIT_LIST_HEAD(&entry->log_list);
        INIT_LIST_HEAD(&entry->root_extent_list);
        INIT_LIST_HEAD(&entry->work_list);
        INIT_LIST_HEAD(&entry->bioc_list);
        init_completion(&entry->completion);

        /*
         * We don't need the count_max_extents here, we can assume that all of
         * that work has been done at higher layers, so this is truly the
         * smallest the extent is going to get.
         */
        spin_lock(&inode->lock);
        btrfs_mod_outstanding_extents(inode, 1);
        spin_unlock(&inode->lock);

out:
        if (IS_ERR(entry) && !is_nocow)
                btrfs_qgroup_free_refroot(inode->root->fs_info,
                                          btrfs_root_id(inode->root),
                                          qgroup_rsv, BTRFS_QGROUP_RSV_DATA);

        return entry;
}

static void insert_ordered_extent(struct btrfs_ordered_extent *entry)
{
        struct btrfs_inode *inode = entry->inode;
        struct btrfs_root *root = inode->root;
        struct btrfs_fs_info *fs_info = root->fs_info;
        struct rb_node *node;

        trace_btrfs_ordered_extent_add(inode, entry);

        percpu_counter_add_batch(&fs_info->ordered_bytes, entry->num_bytes,
                                 fs_info->delalloc_batch);

        /* One ref for the tree. */
        refcount_inc(&entry->refs);

        spin_lock(&inode->ordered_tree_lock);
        node = tree_insert(&inode->ordered_tree, entry->file_offset,
                           &entry->rb_node);
        if (unlikely(node))
                btrfs_panic(fs_info, -EEXIST,
                                "inconsistency in ordered tree at offset %llu",
                                entry->file_offset);
        spin_unlock(&inode->ordered_tree_lock);

        spin_lock(&root->ordered_extent_lock);
        list_add_tail(&entry->root_extent_list,
                      &root->ordered_extents);
        root->nr_ordered_extents++;
        if (root->nr_ordered_extents == 1) {
                spin_lock(&fs_info->ordered_root_lock);
                BUG_ON(!list_empty(&root->ordered_root));
                list_add_tail(&root->ordered_root, &fs_info->ordered_roots);
                spin_unlock(&fs_info->ordered_root_lock);
        }
        spin_unlock(&root->ordered_extent_lock);
}

/*
 * Add an ordered extent to the per-inode tree.
 *
 * @inode:           Inode that this extent is for.
 * @file_offset:     Logical offset in file where the extent starts.
 * @num_bytes:       Logical length of extent in file.
 * @ram_bytes:       Full length of unencoded data.
 * @disk_bytenr:     Offset of extent on disk.
 * @disk_num_bytes:  Size of extent on disk.
 * @offset:          Offset into unencoded data where file data starts.
 * @flags:           Flags specifying type of extent (1U << BTRFS_ORDERED_*).
 * @compress_type:   Compression algorithm used for data.
 *
 * Most of these parameters correspond to &struct btrfs_file_extent_item. The
 * tree is given a single reference on the ordered extent that was inserted, and
 * the returned pointer is given a second reference.
 *
 * Return: the new ordered extent or error pointer.
 */
struct btrfs_ordered_extent *btrfs_alloc_ordered_extent(
                        struct btrfs_inode *inode, u64 file_offset,
                        const struct btrfs_file_extent *file_extent, unsigned long flags)
{
        struct btrfs_ordered_extent *entry;

        ASSERT((flags & ~BTRFS_ORDERED_TYPE_FLAGS) == 0);

        /*
         * For regular writes, we just use the members in @file_extent.
         *
         * For NOCOW, we don't really care about the numbers except @start and
         * file_extent->num_bytes, as we won't insert a file extent item at all.
         *
         * For PREALLOC, we do not use ordered extent members, but
         * btrfs_mark_extent_written() handles everything.
         *
         * So here we always pass 0 as offset for NOCOW/PREALLOC ordered extents,
         * or btrfs_split_ordered_extent() cannot handle it correctly.
         */
        if (flags & ((1U << BTRFS_ORDERED_NOCOW) | (1U << BTRFS_ORDERED_PREALLOC)))
                entry = alloc_ordered_extent(inode, file_offset,
                                             file_extent->num_bytes,
                                             file_extent->num_bytes,
                                             file_extent->disk_bytenr + file_extent->offset,
                                             file_extent->num_bytes, 0, flags,
                                             file_extent->compression);
        else
                entry = alloc_ordered_extent(inode, file_offset,
                                             file_extent->num_bytes,
                                             file_extent->ram_bytes,
                                             file_extent->disk_bytenr,
                                             file_extent->disk_num_bytes,
                                             file_extent->offset, flags,
                                             file_extent->compression);
        if (!IS_ERR(entry))
                insert_ordered_extent(entry);
        return entry;
}

/*
 * Add a struct btrfs_ordered_sum into the list of checksums to be inserted
 * when an ordered extent is finished.  If the list covers more than one
 * ordered extent, it is split across multiples.
 */
void btrfs_add_ordered_sum(struct btrfs_ordered_extent *entry,
                           struct btrfs_ordered_sum *sum)
{
        struct btrfs_inode *inode = entry->inode;

        spin_lock(&inode->ordered_tree_lock);
        list_add_tail(&sum->list, &entry->list);
        spin_unlock(&inode->ordered_tree_lock);
}

void btrfs_mark_ordered_extent_error(struct btrfs_ordered_extent *ordered)
{
        if (!test_and_set_bit(BTRFS_ORDERED_IOERR, &ordered->flags))
                mapping_set_error(ordered->inode->vfs_inode.i_mapping, -EIO);
}

static void finish_ordered_fn(struct btrfs_work *work)
{
        struct btrfs_ordered_extent *ordered_extent;

        ordered_extent = container_of(work, struct btrfs_ordered_extent, work);
        btrfs_finish_ordered_io(ordered_extent);
}

static bool can_finish_ordered_extent(struct btrfs_ordered_extent *ordered,
                                      struct folio *folio, u64 file_offset,
                                      u64 len, bool uptodate)
{
        struct btrfs_inode *inode = ordered->inode;
        struct btrfs_fs_info *fs_info = inode->root->fs_info;

        lockdep_assert_held(&inode->ordered_tree_lock);

        if (folio) {
                ASSERT(folio->mapping);
                ASSERT(folio_pos(folio) <= file_offset);
                ASSERT(file_offset + len <= folio_next_pos(folio));

                /*
                 * Ordered flag indicates whether we still have
                 * pending io unfinished for the ordered extent.
                 *
                 * If it's not set, we need to skip to next range.
                 */
                if (!btrfs_folio_test_ordered(fs_info, folio, file_offset, len))
                        return false;
                btrfs_folio_clear_ordered(fs_info, folio, file_offset, len);
        }

        /* Now we're fine to update the accounting. */
        if (WARN_ON_ONCE(len > ordered->bytes_left)) {
                btrfs_crit(fs_info,
"bad ordered extent accounting, root=%llu ino=%llu OE offset=%llu OE len=%llu to_dec=%llu left=%llu",
                           btrfs_root_id(inode->root), btrfs_ino(inode),
                           ordered->file_offset, ordered->num_bytes,
                           len, ordered->bytes_left);
                ordered->bytes_left = 0;
        } else {
                ordered->bytes_left -= len;
        }

        if (!uptodate)
                set_bit(BTRFS_ORDERED_IOERR, &ordered->flags);

        if (ordered->bytes_left)
                return false;

        /*
         * All the IO of the ordered extent is finished, we need to queue
         * the finish_func to be executed.
         */
        set_bit(BTRFS_ORDERED_IO_DONE, &ordered->flags);
        cond_wake_up(&ordered->wait);
        refcount_inc(&ordered->refs);
        trace_btrfs_ordered_extent_mark_finished(inode, ordered);
        return true;
}

static void btrfs_queue_ordered_fn(struct btrfs_ordered_extent *ordered)
{
        struct btrfs_inode *inode = ordered->inode;
        struct btrfs_fs_info *fs_info = inode->root->fs_info;
        struct btrfs_workqueue *wq = btrfs_is_free_space_inode(inode) ?
                fs_info->endio_freespace_worker : fs_info->endio_write_workers;

        btrfs_init_work(&ordered->work, finish_ordered_fn, NULL);
        btrfs_queue_work(wq, &ordered->work);
}

void btrfs_finish_ordered_extent(struct btrfs_ordered_extent *ordered,
                                 struct folio *folio, u64 file_offset, u64 len,
                                 bool uptodate)
{
        struct btrfs_inode *inode = ordered->inode;
        bool ret;

        trace_btrfs_finish_ordered_extent(inode, file_offset, len, uptodate);

        spin_lock(&inode->ordered_tree_lock);
        ret = can_finish_ordered_extent(ordered, folio, file_offset, len,
                                        uptodate);
        spin_unlock(&inode->ordered_tree_lock);

        /*
         * If this is a COW write it means we created new extent maps for the
         * range and they point to unwritten locations if we got an error either
         * before submitting a bio or during IO.
         *
         * We have marked the ordered extent with BTRFS_ORDERED_IOERR, and we
         * are queuing its completion below. During completion, at
         * btrfs_finish_one_ordered(), we will drop the extent maps for the
         * unwritten extents.
         *
         * However because completion runs in a work queue we can end up having
         * a fast fsync running before that. In the case of direct IO, once we
         * unlock the inode the fsync might start, and we queue the completion
         * before unlocking the inode. In the case of buffered IO when writeback
         * finishes (end_bbio_data_write()) we queue the completion, so if the
         * writeback was triggered by a fast fsync, the fsync might start
         * logging before ordered extent completion runs in the work queue.
         *
         * The fast fsync will log file extent items based on the extent maps it
         * finds, so if by the time it collects extent maps the ordered extent
         * completion didn't happen yet, it will log file extent items that
         * point to unwritten extents, resulting in a corruption if a crash
         * happens and the log tree is replayed. Note that a fast fsync does not
         * wait for completion of ordered extents in order to reduce latency.
         *
         * Set a flag in the inode so that the next fast fsync will wait for
         * ordered extents to complete before starting to log.
         */
        if (!uptodate && !test_bit(BTRFS_ORDERED_NOCOW, &ordered->flags))
                set_bit(BTRFS_INODE_COW_WRITE_ERROR, &inode->runtime_flags);

        if (ret)
                btrfs_queue_ordered_fn(ordered);
}

/*
 * Mark all ordered extents io inside the specified range finished.
 *
 * @folio:       The involved folio for the operation.
 *               For uncompressed buffered IO, the folio status also needs to be
 *               updated to indicate whether the pending ordered io is finished.
 *               Can be NULL for direct IO and compressed write.
 *               For these cases, callers are ensured they won't execute the
 *               endio function twice.
 *
 * This function is called for endio, thus the range must have ordered
 * extent(s) covering it.
 */
void btrfs_mark_ordered_io_finished(struct btrfs_inode *inode,
                                    struct folio *folio, u64 file_offset,
                                    u64 num_bytes, bool uptodate)
{
        struct rb_node *node;
        struct btrfs_ordered_extent *entry = NULL;
        u64 cur = file_offset;
        const u64 end = file_offset + num_bytes;

        trace_btrfs_writepage_end_io_hook(inode, file_offset, end - 1, uptodate);

        spin_lock(&inode->ordered_tree_lock);
        while (cur < end) {
                u64 entry_end;
                u64 this_end;
                u64 len;

                node = ordered_tree_search(inode, cur);
                /* No ordered extents at all */
                if (!node)
                        break;

                entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
                entry_end = entry->file_offset + entry->num_bytes;
                /*
                 * |<-- OE --->|  |
                 *                cur
                 * Go to next OE.
                 */
                if (cur >= entry_end) {
                        node = rb_next(node);
                        /* No more ordered extents, exit */
                        if (!node)
                                break;
                        entry = rb_entry(node, struct btrfs_ordered_extent,
                                         rb_node);

                        /* Go to next ordered extent and continue */
                        cur = entry->file_offset;
                        continue;
                }
                /*
                 * |    |<--- OE --->|
                 * cur
                 * Go to the start of OE.
                 */
                if (cur < entry->file_offset) {
                        cur = entry->file_offset;
                        continue;
                }

                /*
                 * Now we are definitely inside one ordered extent.
                 *
                 * |<--- OE --->|
                 *      |
                 *      cur
                 */
                this_end = min(entry_end, end);
                len = this_end - cur;
                ASSERT(len < U32_MAX);

                if (can_finish_ordered_extent(entry, folio, cur, len, uptodate)) {
                        spin_unlock(&inode->ordered_tree_lock);
                        btrfs_queue_ordered_fn(entry);
                        spin_lock(&inode->ordered_tree_lock);
                }
                cur += len;
        }
        spin_unlock(&inode->ordered_tree_lock);
}

/*
 * Finish IO for one ordered extent across a given range.  The range can only
 * contain one ordered extent.
 *
 * @cached:      The cached ordered extent. If not NULL, we can skip the tree
 *               search and use the ordered extent directly.
 *               Will be also used to store the finished ordered extent.
 * @file_offset: File offset for the finished IO
 * @io_size:     Length of the finish IO range
 *
 * Return true if the ordered extent is finished in the range, and update
 * @cached.
 * Return false otherwise.
 *
 * NOTE: The range can NOT cross multiple ordered extents.
 * Thus caller should ensure the range doesn't cross ordered extents.
 */
bool btrfs_dec_test_ordered_pending(struct btrfs_inode *inode,
                                    struct btrfs_ordered_extent **cached,
                                    u64 file_offset, u64 io_size)
{
        struct rb_node *node;
        struct btrfs_ordered_extent *entry = NULL;
        bool finished = false;

        spin_lock(&inode->ordered_tree_lock);
        if (cached && *cached) {
                entry = *cached;
                goto have_entry;
        }

        node = ordered_tree_search(inode, file_offset);
        if (!node)
                goto out;

        entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
have_entry:
        if (!in_range(file_offset, entry->file_offset, entry->num_bytes))
                goto out;

        if (io_size > entry->bytes_left)
                btrfs_crit(inode->root->fs_info,
                           "bad ordered accounting left %llu size %llu",
                       entry->bytes_left, io_size);

        entry->bytes_left -= io_size;

        if (entry->bytes_left == 0) {
                /*
                 * Ensure only one caller can set the flag and finished_ret
                 * accordingly
                 */
                finished = !test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);
                /* test_and_set_bit implies a barrier */
                cond_wake_up_nomb(&entry->wait);
        }
out:
        if (finished && cached && entry) {
                *cached = entry;
                refcount_inc(&entry->refs);
                trace_btrfs_ordered_extent_dec_test_pending(inode, entry);
        }
        spin_unlock(&inode->ordered_tree_lock);
        return finished;
}

/*
 * used to drop a reference on an ordered extent.  This will free
 * the extent if the last reference is dropped
 */
void btrfs_put_ordered_extent(struct btrfs_ordered_extent *entry)
{
        trace_btrfs_ordered_extent_put(entry->inode, entry);

        if (refcount_dec_and_test(&entry->refs)) {
                struct btrfs_ordered_sum *sum;
                struct btrfs_ordered_sum *tmp;

                ASSERT(list_empty(&entry->root_extent_list));
                ASSERT(list_empty(&entry->log_list));
                ASSERT(RB_EMPTY_NODE(&entry->rb_node));
                btrfs_add_delayed_iput(entry->inode);
                list_for_each_entry_safe(sum, tmp, &entry->list, list)
                        kvfree(sum);
                kmem_cache_free(btrfs_ordered_extent_cache, entry);
        }
}

/*
 * remove an ordered extent from the tree.  No references are dropped
 * and waiters are woken up.
 */
void btrfs_remove_ordered_extent(struct btrfs_inode *btrfs_inode,
                                 struct btrfs_ordered_extent *entry)
{
        struct btrfs_root *root = btrfs_inode->root;
        struct btrfs_fs_info *fs_info = root->fs_info;
        struct rb_node *node;
        bool pending;
        bool freespace_inode;

        /*
         * If this is a free space inode the thread has not acquired the ordered
         * extents lockdep map.
         */
        freespace_inode = btrfs_is_free_space_inode(btrfs_inode);

        btrfs_lockdep_acquire(fs_info, btrfs_trans_pending_ordered);
        /* This is paired with alloc_ordered_extent(). */
        spin_lock(&btrfs_inode->lock);
        btrfs_mod_outstanding_extents(btrfs_inode, -1);
        spin_unlock(&btrfs_inode->lock);
        if (root != fs_info->tree_root) {
                u64 release;

                if (test_bit(BTRFS_ORDERED_ENCODED, &entry->flags))
                        release = entry->disk_num_bytes;
                else
                        release = entry->num_bytes;
                btrfs_delalloc_release_metadata(btrfs_inode, release,
                                                test_bit(BTRFS_ORDERED_IOERR,
                                                         &entry->flags));
        }

        percpu_counter_add_batch(&fs_info->ordered_bytes, -entry->num_bytes,
                                 fs_info->delalloc_batch);

        spin_lock(&btrfs_inode->ordered_tree_lock);
        node = &entry->rb_node;
        rb_erase(node, &btrfs_inode->ordered_tree);
        RB_CLEAR_NODE(node);
        if (btrfs_inode->ordered_tree_last == node)
                btrfs_inode->ordered_tree_last = NULL;
        set_bit(BTRFS_ORDERED_COMPLETE, &entry->flags);
        pending = test_and_clear_bit(BTRFS_ORDERED_PENDING, &entry->flags);
        spin_unlock(&btrfs_inode->ordered_tree_lock);

        /*
         * The current running transaction is waiting on us, we need to let it
         * know that we're complete and wake it up.
         */
        if (pending) {
                struct btrfs_transaction *trans;

                /*
                 * The checks for trans are just a formality, it should be set,
                 * but if it isn't we don't want to deref/assert under the spin
                 * lock, so be nice and check if trans is set, but ASSERT() so
                 * if it isn't set a developer will notice.
                 */
                spin_lock(&fs_info->trans_lock);
                trans = fs_info->running_transaction;
                if (trans)
                        refcount_inc(&trans->use_count);
                spin_unlock(&fs_info->trans_lock);

                ASSERT(trans || BTRFS_FS_ERROR(fs_info));
                if (trans) {
                        if (atomic_dec_and_test(&trans->pending_ordered))
                                wake_up(&trans->pending_wait);
                        btrfs_put_transaction(trans);
                }
        }

        btrfs_lockdep_release(fs_info, btrfs_trans_pending_ordered);

        spin_lock(&root->ordered_extent_lock);
        list_del_init(&entry->root_extent_list);
        root->nr_ordered_extents--;

        trace_btrfs_ordered_extent_remove(btrfs_inode, entry);

        if (!root->nr_ordered_extents) {
                spin_lock(&fs_info->ordered_root_lock);
                BUG_ON(list_empty(&root->ordered_root));
                list_del_init(&root->ordered_root);
                spin_unlock(&fs_info->ordered_root_lock);
        }
        spin_unlock(&root->ordered_extent_lock);
        wake_up(&entry->wait);
        if (!freespace_inode)
                btrfs_lockdep_release(fs_info, btrfs_ordered_extent);
}

static void btrfs_run_ordered_extent_work(struct btrfs_work *work)
{
        struct btrfs_ordered_extent *ordered;

        ordered = container_of(work, struct btrfs_ordered_extent, flush_work);
        btrfs_start_ordered_extent(ordered);
        complete(&ordered->completion);
}

/*
 * Wait for all the ordered extents in a root. Use @bg as range or do whole
 * range if it's NULL.
 */
u64 btrfs_wait_ordered_extents(struct btrfs_root *root, u64 nr,
                               const struct btrfs_block_group *bg)
{
        struct btrfs_fs_info *fs_info = root->fs_info;
        LIST_HEAD(splice);
        LIST_HEAD(skipped);
        LIST_HEAD(works);
        struct btrfs_ordered_extent *ordered, *next;
        u64 count = 0;
        u64 range_start, range_len;
        u64 range_end;

        if (bg) {
                range_start = bg->start;
                range_len = bg->length;
        } else {
                range_start = 0;
                range_len = U64_MAX;
        }
        range_end = range_start + range_len;

        mutex_lock(&root->ordered_extent_mutex);
        spin_lock(&root->ordered_extent_lock);
        list_splice_init(&root->ordered_extents, &splice);
        while (!list_empty(&splice) && nr) {
                ordered = list_first_entry(&splice, struct btrfs_ordered_extent,
                                           root_extent_list);

                if (range_end <= ordered->disk_bytenr ||
                    ordered->disk_bytenr + ordered->disk_num_bytes <= range_start) {
                        list_move_tail(&ordered->root_extent_list, &skipped);
                        cond_resched_lock(&root->ordered_extent_lock);
                        continue;
                }

                list_move_tail(&ordered->root_extent_list,
                               &root->ordered_extents);
                refcount_inc(&ordered->refs);
                spin_unlock(&root->ordered_extent_lock);

                btrfs_init_work(&ordered->flush_work,
                                btrfs_run_ordered_extent_work, NULL);
                list_add_tail(&ordered->work_list, &works);
                btrfs_queue_work(fs_info->flush_workers, &ordered->flush_work);

                cond_resched();
                if (nr != U64_MAX)
                        nr--;
                count++;
                spin_lock(&root->ordered_extent_lock);
        }
        list_splice_tail(&skipped, &root->ordered_extents);
        list_splice_tail(&splice, &root->ordered_extents);
        spin_unlock(&root->ordered_extent_lock);

        list_for_each_entry_safe(ordered, next, &works, work_list) {
                list_del_init(&ordered->work_list);
                wait_for_completion(&ordered->completion);
                btrfs_put_ordered_extent(ordered);
                cond_resched();
        }
        mutex_unlock(&root->ordered_extent_mutex);

        return count;
}

/*
 * Wait for @nr ordered extents that intersect the @bg, or the whole range of
 * the filesystem if @bg is NULL.
 */
void btrfs_wait_ordered_roots(struct btrfs_fs_info *fs_info, u64 nr,
                              const struct btrfs_block_group *bg)
{
        struct btrfs_root *root;
        LIST_HEAD(splice);
        u64 done;

        mutex_lock(&fs_info->ordered_operations_mutex);
        spin_lock(&fs_info->ordered_root_lock);
        list_splice_init(&fs_info->ordered_roots, &splice);
        while (!list_empty(&splice) && nr) {
                root = list_first_entry(&splice, struct btrfs_root,
                                        ordered_root);
                root = btrfs_grab_root(root);
                BUG_ON(!root);
                list_move_tail(&root->ordered_root,
                               &fs_info->ordered_roots);
                spin_unlock(&fs_info->ordered_root_lock);

                done = btrfs_wait_ordered_extents(root, nr, bg);
                btrfs_put_root(root);

                if (nr != U64_MAX)
                        nr -= done;

                spin_lock(&fs_info->ordered_root_lock);
        }
        list_splice_tail(&splice, &fs_info->ordered_roots);
        spin_unlock(&fs_info->ordered_root_lock);
        mutex_unlock(&fs_info->ordered_operations_mutex);
}

/*
 * Start IO and wait for a given ordered extent to finish.
 *
 * Wait on page writeback for all the pages in the extent but not in
 * [@nowriteback_start, @nowriteback_start + @nowriteback_len) and the
 * IO completion code to insert metadata into the btree corresponding to the extent.
 */
void btrfs_start_ordered_extent_nowriteback(struct btrfs_ordered_extent *entry,
                                            u64 nowriteback_start, u32 nowriteback_len)
{
        u64 start = entry->file_offset;
        u64 end = start + entry->num_bytes - 1;
        struct btrfs_inode *inode = entry->inode;
        bool freespace_inode;

        trace_btrfs_ordered_extent_start(inode, entry);

        /*
         * If this is a free space inode do not take the ordered extents lockdep
         * map.
         */
        freespace_inode = btrfs_is_free_space_inode(inode);

        /*
         * pages in the range can be dirty, clean or writeback.  We
         * start IO on any dirty ones so the wait doesn't stall waiting
         * for the flusher thread to find them
         */
        if (!test_bit(BTRFS_ORDERED_DIRECT, &entry->flags)) {
                if (!nowriteback_len) {
                        filemap_fdatawrite_range(inode->vfs_inode.i_mapping, start, end);
                } else {
                        if (start < nowriteback_start)
                                filemap_fdatawrite_range(inode->vfs_inode.i_mapping, start,
                                                         nowriteback_start - 1);
                        if (nowriteback_start + nowriteback_len < end)
                                filemap_fdatawrite_range(inode->vfs_inode.i_mapping,
                                                         nowriteback_start + nowriteback_len,
                                                         end);
                }
        }

        if (!freespace_inode)
                btrfs_might_wait_for_event(inode->root->fs_info, btrfs_ordered_extent);
        wait_event(entry->wait, test_bit(BTRFS_ORDERED_COMPLETE, &entry->flags));
}

/*
 * Used to wait on ordered extents across a large range of bytes.
 */
int btrfs_wait_ordered_range(struct btrfs_inode *inode, u64 start, u64 len)
{
        int ret = 0;
        int ret_wb = 0;
        u64 end;
        u64 orig_end;
        struct btrfs_ordered_extent *ordered;

        if (start + len < start) {
                orig_end = OFFSET_MAX;
        } else {
                orig_end = start + len - 1;
                if (orig_end > OFFSET_MAX)
                        orig_end = OFFSET_MAX;
        }

        /* start IO across the range first to instantiate any delalloc
         * extents
         */
        ret = btrfs_fdatawrite_range(inode, start, orig_end);
        if (ret)
                return ret;

        /*
         * If we have a writeback error don't return immediately. Wait first
         * for any ordered extents that haven't completed yet. This is to make
         * sure no one can dirty the same page ranges and call writepages()
         * before the ordered extents complete - to avoid failures (-EEXIST)
         * when adding the new ordered extents to the ordered tree.
         */
        ret_wb = filemap_fdatawait_range(inode->vfs_inode.i_mapping, start, orig_end);

        end = orig_end;
        while (1) {
                ordered = btrfs_lookup_first_ordered_extent(inode, end);
                if (!ordered)
                        break;
                if (ordered->file_offset > orig_end) {
                        btrfs_put_ordered_extent(ordered);
                        break;
                }
                if (ordered->file_offset + ordered->num_bytes <= start) {
                        btrfs_put_ordered_extent(ordered);
                        break;
                }
                btrfs_start_ordered_extent(ordered);
                end = ordered->file_offset;
                /*
                 * If the ordered extent had an error save the error but don't
                 * exit without waiting first for all other ordered extents in
                 * the range to complete.
                 */
                if (test_bit(BTRFS_ORDERED_IOERR, &ordered->flags))
                        ret = -EIO;
                btrfs_put_ordered_extent(ordered);
                if (end == 0 || end == start)
                        break;
                end--;
        }
        return ret_wb ? ret_wb : ret;
}

/*
 * find an ordered extent corresponding to file_offset.  return NULL if
 * nothing is found, otherwise take a reference on the extent and return it
 */
struct btrfs_ordered_extent *btrfs_lookup_ordered_extent(struct btrfs_inode *inode,
                                                         u64 file_offset)
{
        struct rb_node *node;
        struct btrfs_ordered_extent *entry = NULL;

        spin_lock(&inode->ordered_tree_lock);
        node = ordered_tree_search(inode, file_offset);
        if (!node)
                goto out;

        entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
        if (!in_range(file_offset, entry->file_offset, entry->num_bytes))
                entry = NULL;
        if (entry) {
                refcount_inc(&entry->refs);
                trace_btrfs_ordered_extent_lookup(inode, entry);
        }
out:
        spin_unlock(&inode->ordered_tree_lock);
        return entry;
}

/* Since the DIO code tries to lock a wide area we need to look for any ordered
 * extents that exist in the range, rather than just the start of the range.
 */
struct btrfs_ordered_extent *btrfs_lookup_ordered_range(
                struct btrfs_inode *inode, u64 file_offset, u64 len)
{
        struct rb_node *node;
        struct btrfs_ordered_extent *entry = NULL;

        spin_lock(&inode->ordered_tree_lock);
        node = ordered_tree_search(inode, file_offset);
        if (!node) {
                node = ordered_tree_search(inode, file_offset + len);
                if (!node)
                        goto out;
        }

        while (1) {
                entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
                if (btrfs_range_overlaps(entry, file_offset, len))
                        break;

                if (entry->file_offset >= file_offset + len) {
                        entry = NULL;
                        break;
                }
                entry = NULL;
                node = rb_next(node);
                if (!node)
                        break;
        }
out:
        if (entry) {
                refcount_inc(&entry->refs);
                trace_btrfs_ordered_extent_lookup_range(inode, entry);
        }
        spin_unlock(&inode->ordered_tree_lock);
        return entry;
}

/*
 * Adds all ordered extents to the given list. The list ends up sorted by the
 * file_offset of the ordered extents.
 */
void btrfs_get_ordered_extents_for_logging(struct btrfs_inode *inode,
                                           struct list_head *list)
{
        struct rb_node *n;

        btrfs_assert_inode_locked(inode);

        spin_lock(&inode->ordered_tree_lock);
        for (n = rb_first(&inode->ordered_tree); n; n = rb_next(n)) {
                struct btrfs_ordered_extent *ordered;

                ordered = rb_entry(n, struct btrfs_ordered_extent, rb_node);

                if (test_bit(BTRFS_ORDERED_LOGGED, &ordered->flags))
                        continue;

                ASSERT(list_empty(&ordered->log_list));
                list_add_tail(&ordered->log_list, list);
                refcount_inc(&ordered->refs);
                trace_btrfs_ordered_extent_lookup_for_logging(inode, ordered);
        }
        spin_unlock(&inode->ordered_tree_lock);
}

/*
 * lookup and return any extent before 'file_offset'.  NULL is returned
 * if none is found
 */
struct btrfs_ordered_extent *
btrfs_lookup_first_ordered_extent(struct btrfs_inode *inode, u64 file_offset)
{
        struct rb_node *node;
        struct btrfs_ordered_extent *entry = NULL;

        spin_lock(&inode->ordered_tree_lock);
        node = ordered_tree_search(inode, file_offset);
        if (!node)
                goto out;

        entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
        refcount_inc(&entry->refs);
        trace_btrfs_ordered_extent_lookup_first(inode, entry);
out:
        spin_unlock(&inode->ordered_tree_lock);
        return entry;
}

/*
 * Lookup the first ordered extent that overlaps the range
 * [@file_offset, @file_offset + @len).
 *
 * The difference between this and btrfs_lookup_first_ordered_extent() is
 * that this one won't return any ordered extent that does not overlap the range.
 * And the difference against btrfs_lookup_ordered_extent() is, this function
 * ensures the first ordered extent gets returned.
 */
struct btrfs_ordered_extent *btrfs_lookup_first_ordered_range(
                        struct btrfs_inode *inode, u64 file_offset, u64 len)
{
        struct rb_node *node;
        struct rb_node *cur;
        struct rb_node *prev;
        struct rb_node *next;
        struct btrfs_ordered_extent *entry = NULL;

        spin_lock(&inode->ordered_tree_lock);
        node = inode->ordered_tree.rb_node;
        /*
         * Here we don't want to use tree_search() which will use tree->last
         * and screw up the search order.
         * And __tree_search() can't return the adjacent ordered extents
         * either, thus here we do our own search.
         */
        while (node) {
                entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);

                if (file_offset < entry->file_offset) {
                        node = node->rb_left;
                } else if (file_offset >= entry_end(entry)) {
                        node = node->rb_right;
                } else {
                        /*
                         * Direct hit, got an ordered extent that starts at
                         * @file_offset
                         */
                        goto out;
                }
        }
        if (!entry) {
                /* Empty tree */
                goto out;
        }

        cur = &entry->rb_node;
        /* We got an entry around @file_offset, check adjacent entries */
        if (entry->file_offset < file_offset) {
                prev = cur;
                next = rb_next(cur);
        } else {
                prev = rb_prev(cur);
                next = cur;
        }
        if (prev) {
                entry = rb_entry(prev, struct btrfs_ordered_extent, rb_node);
                if (btrfs_range_overlaps(entry, file_offset, len))
                        goto out;
        }
        if (next) {
                entry = rb_entry(next, struct btrfs_ordered_extent, rb_node);
                if (btrfs_range_overlaps(entry, file_offset, len))
                        goto out;
        }
        /* No ordered extent in the range */
        entry = NULL;
out:
        if (entry) {
                refcount_inc(&entry->refs);
                trace_btrfs_ordered_extent_lookup_first_range(inode, entry);
        }

        spin_unlock(&inode->ordered_tree_lock);
        return entry;
}

/*
 * Lock the passed range and ensures all pending ordered extents in it are run
 * to completion.
 *
 * @inode:        Inode whose ordered tree is to be searched
 * @start:        Beginning of range to flush
 * @end:          Last byte of range to lock
 * @cached_state: If passed, will return the extent state responsible for the
 *                locked range. It's the caller's responsibility to free the
 *                cached state.
 *
 * Always return with the given range locked, ensuring after it's called no
 * order extent can be pending.
 */
void btrfs_lock_and_flush_ordered_range(struct btrfs_inode *inode, u64 start,
                                        u64 end,
                                        struct extent_state **cached_state)
{
        struct btrfs_ordered_extent *ordered;
        struct extent_state *cache = NULL;
        struct extent_state **cachedp = &cache;

        if (cached_state)
                cachedp = cached_state;

        while (1) {
                btrfs_lock_extent(&inode->io_tree, start, end, cachedp);
                ordered = btrfs_lookup_ordered_range(inode, start,
                                                     end - start + 1);
                if (!ordered) {
                        /*
                         * If no external cached_state has been passed then
                         * decrement the extra ref taken for cachedp since we
                         * aren't exposing it outside of this function
                         */
                        if (!cached_state)
                                refcount_dec(&cache->refs);
                        break;
                }
                btrfs_unlock_extent(&inode->io_tree, start, end, cachedp);
                btrfs_start_ordered_extent(ordered);
                btrfs_put_ordered_extent(ordered);
        }
}

/*
 * Lock the passed range and ensure all pending ordered extents in it are run
 * to completion in nowait mode.
 *
 * Return true if btrfs_lock_ordered_range does not return any extents,
 * otherwise false.
 */
bool btrfs_try_lock_ordered_range(struct btrfs_inode *inode, u64 start, u64 end,
                                  struct extent_state **cached_state)
{
        struct btrfs_ordered_extent *ordered;

        if (!btrfs_try_lock_extent(&inode->io_tree, start, end, cached_state))
                return false;

        ordered = btrfs_lookup_ordered_range(inode, start, end - start + 1);
        if (!ordered)
                return true;

        btrfs_put_ordered_extent(ordered);
        btrfs_unlock_extent(&inode->io_tree, start, end, cached_state);

        return false;
}

/* Split out a new ordered extent for this first @len bytes of @ordered. */
struct btrfs_ordered_extent *btrfs_split_ordered_extent(
                        struct btrfs_ordered_extent *ordered, u64 len)
{
        struct btrfs_inode *inode = ordered->inode;
        struct btrfs_root *root = inode->root;
        struct btrfs_fs_info *fs_info = root->fs_info;
        u64 file_offset = ordered->file_offset;
        u64 disk_bytenr = ordered->disk_bytenr;
        unsigned long flags = ordered->flags;
        struct btrfs_ordered_sum *sum, *tmpsum;
        struct btrfs_ordered_extent *new;
        struct rb_node *node;
        u64 offset = 0;

        trace_btrfs_ordered_extent_split(inode, ordered);

        ASSERT(!(flags & (1U << BTRFS_ORDERED_COMPRESSED)));

        /*
         * The entire bio must be covered by the ordered extent, but we can't
         * reduce the original extent to a zero length either.
         */
        if (WARN_ON_ONCE(len >= ordered->num_bytes))
                return ERR_PTR(-EINVAL);
        /*
         * If our ordered extent had an error there's no point in continuing.
         * The error may have come from a transaction abort done either by this
         * task or some other concurrent task, and the transaction abort path
         * iterates over all existing ordered extents and sets the flag
         * BTRFS_ORDERED_IOERR on them.
         */
        if (unlikely(flags & (1U << BTRFS_ORDERED_IOERR))) {
                const int fs_error = BTRFS_FS_ERROR(fs_info);

                return fs_error ? ERR_PTR(fs_error) : ERR_PTR(-EIO);
        }
        /* We cannot split partially completed ordered extents. */
        if (ordered->bytes_left) {
                ASSERT(!(flags & ~BTRFS_ORDERED_TYPE_FLAGS));
                if (WARN_ON_ONCE(ordered->bytes_left != ordered->disk_num_bytes))
                        return ERR_PTR(-EINVAL);
        }
        /* We cannot split a compressed ordered extent. */
        if (WARN_ON_ONCE(ordered->disk_num_bytes != ordered->num_bytes))
                return ERR_PTR(-EINVAL);

        new = alloc_ordered_extent(inode, file_offset, len, len, disk_bytenr,
                                   len, 0, flags, ordered->compress_type);
        if (IS_ERR(new))
                return new;

        /* One ref for the tree. */
        refcount_inc(&new->refs);

        /*
         * Take the root's ordered_extent_lock to avoid a race with
         * btrfs_wait_ordered_extents() when updating the disk_bytenr and
         * disk_num_bytes fields of the ordered extent below.
         *
         * There's no concern about a previous caller of
         * btrfs_wait_ordered_extents() getting the trimmed ordered extent
         * before we insert the new one, because even if it gets the ordered
         * extent before it's trimmed and the new one inserted, right before it
         * uses it or during its use, the ordered extent might have been
         * trimmed in the meanwhile, and it missed the new ordered extent.
         * There's no way around this and it's harmless for current use cases,
         * so we take the root's ordered_extent_lock to fix that race during
         * trimming and silence tools like KCSAN.
         */
        spin_lock_irq(&root->ordered_extent_lock);
        spin_lock(&inode->ordered_tree_lock);

        /*
         * We don't have overlapping ordered extents (that would imply double
         * allocation of extents) and we checked above that the split length
         * does not cross the ordered extent's num_bytes field, so there's
         * no need to remove it and re-insert it in the tree.
         */
        ordered->file_offset += len;
        ordered->disk_bytenr += len;
        ordered->num_bytes -= len;
        ordered->disk_num_bytes -= len;
        ordered->ram_bytes -= len;

        if (test_bit(BTRFS_ORDERED_IO_DONE, &ordered->flags)) {
                ASSERT(ordered->bytes_left == 0);
                new->bytes_left = 0;
        } else {
                ordered->bytes_left -= len;
        }

        if (test_bit(BTRFS_ORDERED_TRUNCATED, &ordered->flags)) {
                if (ordered->truncated_len > len) {
                        ordered->truncated_len -= len;
                } else {
                        new->truncated_len = ordered->truncated_len;
                        ordered->truncated_len = 0;
                }
        }

        list_for_each_entry_safe(sum, tmpsum, &ordered->list, list) {
                if (offset == len)
                        break;
                list_move_tail(&sum->list, &new->list);
                offset += sum->len;
        }

        node = tree_insert(&inode->ordered_tree, new->file_offset, &new->rb_node);
        if (unlikely(node))
                btrfs_panic(fs_info, -EEXIST,
                        "inconsistency in ordered tree at offset %llu after split",
                        new->file_offset);
        spin_unlock(&inode->ordered_tree_lock);

        list_add_tail(&new->root_extent_list, &root->ordered_extents);
        root->nr_ordered_extents++;
        spin_unlock_irq(&root->ordered_extent_lock);
        return new;
}

int __init ordered_data_init(void)
{
        btrfs_ordered_extent_cache = KMEM_CACHE(btrfs_ordered_extent, 0);
        if (!btrfs_ordered_extent_cache)
                return -ENOMEM;

        return 0;
}

void __cold ordered_data_exit(void)
{
        kmem_cache_destroy(btrfs_ordered_extent_cache);
}