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| author | Zhao Lei <zhaolei@cn.fujitsu.com> | 2016-01-06 18:24:43 +0800 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2016-02-18 13:18:06 +0100 |
| commit | 4da2e26a2a32b174878744bd0f07db180c875f26 (patch) | |
| tree | 6418afad08a321846e0b39ed430507cde3e83cc5 /fs | |
| parent | 388f7b1d6e8ca06762e2454d28d6c3c55ad0fe95 (diff) | |
| download | linux-4da2e26a2a32b174878744bd0f07db180c875f26.tar.gz linux-4da2e26a2a32b174878744bd0f07db180c875f26.tar.bz2 linux-4da2e26a2a32b174878744bd0f07db180c875f26.zip | |
btrfs: Continue write in case of can_not_nocow
btrfs failed in xfstests btrfs/080 with -o nodatacow.
Can be reproduced by following script:
DEV=/dev/vdg
MNT=/mnt/tmp
umount $DEV &>/dev/null
mkfs.btrfs -f $DEV
mount -o nodatacow $DEV $MNT
dd if=/dev/zero of=$MNT/test bs=1 count=2048 &
btrfs subvolume snapshot -r $MNT $MNT/test_snap &
wait
--
We can see dd failed on NO_SPACE.
Reason:
__btrfs_buffered_write should run cow write when no_cow impossible,
and current code is designed with above logic.
But check_can_nocow() have 2 type of return value(0 and <0) on
can_not_no_cow, and current code only continue write on first case,
the second case happened in doing subvolume.
Fix:
Continue write when check_can_nocow() return 0 and <0.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/btrfs/file.c | 37 |
1 files changed, 17 insertions, 20 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 098bb8f690c9..cadfebaaf8c4 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1525,27 +1525,24 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file, reserve_bytes = num_pages << PAGE_CACHE_SHIFT; - if (BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW | - BTRFS_INODE_PREALLOC)) { - ret = check_can_nocow(inode, pos, &write_bytes); - if (ret < 0) - break; - if (ret > 0) { - /* - * For nodata cow case, no need to reserve - * data space. - */ - only_release_metadata = true; - /* - * our prealloc extent may be smaller than - * write_bytes, so scale down. - */ - num_pages = DIV_ROUND_UP(write_bytes + offset, - PAGE_CACHE_SIZE); - reserve_bytes = num_pages << PAGE_CACHE_SHIFT; - goto reserve_metadata; - } + if ((BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW | + BTRFS_INODE_PREALLOC)) && + check_can_nocow(inode, pos, &write_bytes) > 0) { + /* + * For nodata cow case, no need to reserve + * data space. + */ + only_release_metadata = true; + /* + * our prealloc extent may be smaller than + * write_bytes, so scale down. + */ + num_pages = DIV_ROUND_UP(write_bytes + offset, + PAGE_CACHE_SIZE); + reserve_bytes = num_pages << PAGE_CACHE_SHIFT; + goto reserve_metadata; } + ret = btrfs_check_data_free_space(inode, pos, write_bytes); if (ret < 0) break; |