root/fs/hpfs/file.c
// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/fs/hpfs/file.c
 *
 *  Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz), 1998-1999
 *
 *  file VFS functions
 */

#include "hpfs_fn.h"
#include <linux/mpage.h>
#include <linux/iomap.h>
#include <linux/fiemap.h>

#define BLOCKS(size) (((size) + 511) >> 9)

static int hpfs_file_release(struct inode *inode, struct file *file)
{
        hpfs_lock(inode->i_sb);
        hpfs_write_if_changed(inode);
        hpfs_unlock(inode->i_sb);
        return 0;
}

int hpfs_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)
{
        struct inode *inode = file->f_mapping->host;
        int ret;

        ret = file_write_and_wait_range(file, start, end);
        if (ret)
                return ret;
        return sync_blockdev(inode->i_sb->s_bdev);
}

/*
 * generic_file_read often calls bmap with non-existing sector,
 * so we must ignore such errors.
 */

static secno hpfs_bmap(struct inode *inode, unsigned file_secno, unsigned *n_secs)
{
        struct hpfs_inode_info *hpfs_inode = hpfs_i(inode);
        unsigned n, disk_secno;
        struct fnode *fnode;
        struct buffer_head *bh;
        if (BLOCKS(hpfs_i(inode)->mmu_private) <= file_secno) return 0;
        n = file_secno - hpfs_inode->i_file_sec;
        if (n < hpfs_inode->i_n_secs) {
                *n_secs = hpfs_inode->i_n_secs - n;
                return hpfs_inode->i_disk_sec + n;
        }
        if (!(fnode = hpfs_map_fnode(inode->i_sb, inode->i_ino, &bh))) return 0;
        disk_secno = hpfs_bplus_lookup(inode->i_sb, inode,
                                       GET_BTREE_PTR(&fnode->btree),
                                       file_secno, bh);
        if (disk_secno == -1) return 0;
        if (hpfs_chk_sectors(inode->i_sb, disk_secno, 1, "bmap")) return 0;
        n = file_secno - hpfs_inode->i_file_sec;
        if (n < hpfs_inode->i_n_secs) {
                *n_secs = hpfs_inode->i_n_secs - n;
                return hpfs_inode->i_disk_sec + n;
        }
        *n_secs = 1;
        return disk_secno;
}

void hpfs_truncate(struct inode *i)
{
        if (IS_IMMUTABLE(i)) return /*-EPERM*/;
        hpfs_lock_assert(i->i_sb);

        hpfs_i(i)->i_n_secs = 0;
        i->i_blocks = 1 + ((i->i_size + 511) >> 9);
        hpfs_i(i)->mmu_private = i->i_size;
        hpfs_truncate_btree(i->i_sb, i->i_ino, 1, ((i->i_size + 511) >> 9));
        hpfs_write_inode(i);
        hpfs_i(i)->i_n_secs = 0;
}

static int hpfs_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create)
{
        int r;
        secno s;
        unsigned n_secs;
        hpfs_lock(inode->i_sb);
        s = hpfs_bmap(inode, iblock, &n_secs);
        if (s) {
                if (bh_result->b_size >> 9 < n_secs)
                        n_secs = bh_result->b_size >> 9;
                n_secs = hpfs_search_hotfix_map_for_range(inode->i_sb, s, n_secs);
                if (unlikely(!n_secs)) {
                        s = hpfs_search_hotfix_map(inode->i_sb, s);
                        n_secs = 1;
                }
                map_bh(bh_result, inode->i_sb, s);
                bh_result->b_size = n_secs << 9;
                goto ret_0;
        }
        if (!create) goto ret_0;
        if (iblock<<9 != hpfs_i(inode)->mmu_private) {
                BUG();
                r = -EIO;
                goto ret_r;
        }
        if ((s = hpfs_add_sector_to_btree(inode->i_sb, inode->i_ino, 1, inode->i_blocks - 1)) == -1) {
                hpfs_truncate_btree(inode->i_sb, inode->i_ino, 1, inode->i_blocks - 1);
                r = -ENOSPC;
                goto ret_r;
        }
        inode->i_blocks++;
        hpfs_i(inode)->mmu_private += 512;
        set_buffer_new(bh_result);
        map_bh(bh_result, inode->i_sb, hpfs_search_hotfix_map(inode->i_sb, s));
        ret_0:
        r = 0;
        ret_r:
        hpfs_unlock(inode->i_sb);
        return r;
}

static int hpfs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
                unsigned flags, struct iomap *iomap, struct iomap *srcmap)
{
        struct super_block *sb = inode->i_sb;
        unsigned int blkbits = inode->i_blkbits;
        unsigned int n_secs;
        secno s;

        if (WARN_ON_ONCE(flags & (IOMAP_WRITE | IOMAP_ZERO)))
                return -EINVAL;

        iomap->bdev = inode->i_sb->s_bdev;
        iomap->offset = offset;

        hpfs_lock(sb);
        s = hpfs_bmap(inode, offset >> blkbits, &n_secs);
        if (s) {
                n_secs = hpfs_search_hotfix_map_for_range(sb, s,
                                min_t(loff_t, n_secs, length));
                if (unlikely(!n_secs)) {
                        s = hpfs_search_hotfix_map(sb, s);
                        n_secs = 1;
                }
                iomap->type = IOMAP_MAPPED;
                iomap->flags = IOMAP_F_MERGED;
                iomap->addr = (u64)s << blkbits;
                iomap->length = (u64)n_secs << blkbits;
        } else {
                iomap->type = IOMAP_HOLE;
                iomap->addr = IOMAP_NULL_ADDR;
                iomap->length = 1 << blkbits;
        }

        hpfs_unlock(sb);
        return 0;
}

static const struct iomap_ops hpfs_iomap_ops = {
        .iomap_begin            = hpfs_iomap_begin,
};

static int hpfs_read_folio(struct file *file, struct folio *folio)
{
        return mpage_read_folio(folio, hpfs_get_block);
}

static void hpfs_readahead(struct readahead_control *rac)
{
        mpage_readahead(rac, hpfs_get_block);
}

static int hpfs_writepages(struct address_space *mapping,
                           struct writeback_control *wbc)
{
        return mpage_writepages(mapping, wbc, hpfs_get_block);
}

static void hpfs_write_failed(struct address_space *mapping, loff_t to)
{
        struct inode *inode = mapping->host;

        hpfs_lock(inode->i_sb);

        if (to > inode->i_size) {
                truncate_pagecache(inode, inode->i_size);
                hpfs_truncate(inode);
        }

        hpfs_unlock(inode->i_sb);
}

static int hpfs_write_begin(const struct kiocb *iocb,
                            struct address_space *mapping,
                            loff_t pos, unsigned len,
                            struct folio **foliop, void **fsdata)
{
        int ret;

        ret = cont_write_begin(iocb, mapping, pos, len, foliop, fsdata,
                                hpfs_get_block,
                                &hpfs_i(mapping->host)->mmu_private);
        if (unlikely(ret))
                hpfs_write_failed(mapping, pos + len);

        return ret;
}

static int hpfs_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 err;
        err = generic_write_end(iocb, mapping, pos, len, copied, folio, fsdata);
        if (err < len)
                hpfs_write_failed(mapping, pos + len);
        if (!(err < 0)) {
                /* make sure we write it on close, if not earlier */
                hpfs_lock(inode->i_sb);
                hpfs_i(inode)->i_dirty = 1;
                hpfs_unlock(inode->i_sb);
        }
        return err;
}

static sector_t _hpfs_bmap(struct address_space *mapping, sector_t block)
{
        return generic_block_bmap(mapping, block, hpfs_get_block);
}

static int hpfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, u64 start, u64 len)
{
        int ret;

        inode_lock(inode);
        len = min_t(u64, len, i_size_read(inode));
        ret = iomap_fiemap(inode, fieinfo, start, len, &hpfs_iomap_ops);
        inode_unlock(inode);

        return ret;
}

const struct address_space_operations hpfs_aops = {
        .dirty_folio    = block_dirty_folio,
        .invalidate_folio = block_invalidate_folio,
        .read_folio = hpfs_read_folio,
        .readahead = hpfs_readahead,
        .writepages = hpfs_writepages,
        .write_begin = hpfs_write_begin,
        .write_end = hpfs_write_end,
        .bmap = _hpfs_bmap,
        .migrate_folio = buffer_migrate_folio,
};

const struct file_operations hpfs_file_ops =
{
        .llseek         = generic_file_llseek,
        .read_iter      = generic_file_read_iter,
        .write_iter     = generic_file_write_iter,
        .mmap_prepare   = generic_file_mmap_prepare,
        .release        = hpfs_file_release,
        .fsync          = hpfs_file_fsync,
        .splice_read    = filemap_splice_read,
        .unlocked_ioctl = hpfs_ioctl,
        .compat_ioctl   = compat_ptr_ioctl,
};

const struct inode_operations hpfs_file_iops =
{
        .setattr        = hpfs_setattr,
        .fiemap         = hpfs_fiemap,
};