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btrfs: fix iomap_begin length for nocow writes

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can_nocow_extent can reduce the len passed in, which needs to be
propagated to btrfs_dio_iomap_begin so that iomap does not submit
more data then is mapped.

This problems exists since the btrfs_get_blocks_direct helper was added
in commit c5794e5178 ("btrfs: Factor out write portion of
btrfs_get_blocks_direct"), but the ordered_extent splitting added in
commit b73a6fd1b1 ("btrfs: split partial dio bios before submit")
added a WARN_ON that made a syzkaller test fail.

Reported-by: syzbot+ee90502d5c8fd1d0dd93@syzkaller.appspotmail.com
Fixes: c5794e5178 ("btrfs: Factor out write portion of btrfs_get_blocks_direct")
CC: stable@vger.kernel.org # 6.1+
Tested-by: syzbot+ee90502d5c8fd1d0dd93@syzkaller.appspotmail.com
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Christoph Hellwig 2023-06-08 11:10:25 +02:00 committed by David Sterba
parent 79b8ee702c
commit 7833b86595
1 changed files with 12 additions and 6 deletions
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18
fs/btrfs/inode.c
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@ -7264,7 +7264,7 @@ static struct extent_map *create_io_em(struct btrfs_inode *inode, u64 start,
static int btrfs_get_blocks_direct_write(struct extent_map **map,
struct inode *inode,
struct btrfs_dio_data *dio_data,
u64 start, u64 len,
u64 start, u64 *lenp,
unsigned int iomap_flags)
{
const bool nowait = (iomap_flags & IOMAP_NOWAIT);
@ -7275,6 +7275,7 @@ static int btrfs_get_blocks_direct_write(struct extent_map **map,
struct btrfs_block_group *bg;
bool can_nocow = false;
bool space_reserved = false;
u64 len = *lenp;
u64 prev_len;
int ret = 0;
@ -7345,15 +7346,19 @@ static int btrfs_get_blocks_direct_write(struct extent_map **map,
free_extent_map(em);
*map = NULL;
if (nowait)
return -EAGAIN;
if (nowait) {
ret = -EAGAIN;
goto out;
}
/*
* If we could not allocate data space before locking the file
* range and we can't do a NOCOW write, then we have to fail.
*/
if (!dio_data->data_space_reserved)
return -ENOSPC;
if (!dio_data->data_space_reserved) {
ret = -ENOSPC;
goto out;
}
/*
* We have to COW and we have already reserved data space before,
@ -7394,6 +7399,7 @@ out:
btrfs_delalloc_release_extents(BTRFS_I(inode), len);
btrfs_delalloc_release_metadata(BTRFS_I(inode), len, true);
}
*lenp = len;
return ret;
}
@ -7570,7 +7576,7 @@ static int btrfs_dio_iomap_begin(struct inode *inode, loff_t start,
if (write) {
ret = btrfs_get_blocks_direct_write(&em, inode, dio_data,
start, len, flags);
start, &len, flags);
if (ret < 0)
goto unlock_err;
unlock_extents = true;