On Sat, Apr 4, 2020 at 9:21 PM <fdmanana@xxxxxxxxxx> wrote:
>
> From: Filipe Manana <fdmanana@xxxxxxxx>
>
> When not using the NO_HOLES feature we were not marking the destination's
> file range as written after cloning an inline extent into it. This can
> lead to a data loss if the current destination file size is smaller than
> the source file's size.
>
> Example:
>
> $ mkfs.btrfs -f -O ^no-holes /dev/sdc
> $ mount /mnt/sdc /mnt
>
> $ echo "hello world" > /mnt/foo
> $ cp --reflink=always /mnt/foo /mnt/bar
> $ rm -f /mnt/foo
> $ umount /mnt
>
> $ mount /mnt/sdc /mnt
> $ cat /mnt/bar
> $
> $ stat -c %s /mnt/bar
> 0
>
> # -> the file is empty, since we deleted foo, the data lost is forever
>
> Fix that by calling btrfs_inode_set_file_extent_range() after cloning an
> inline extent.
>
> A test case for fstests will follow soon.
>
> Fixes: 9ddc959e802bf ("btrfs: use the file extent tree infrastructure")
> Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
Reported-by: Johannes Hirte <johannes.hirte@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/linux-btrfs/20200404193846.GA432065@latitude/
Tested-by: Johannes Hirte <johannes.hirte@xxxxxxxxxxxxx>
> ---
> fs/btrfs/reflink.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/fs/btrfs/reflink.c b/fs/btrfs/reflink.c
> index d1973141d3bb..040009d1cc31 100644
> --- a/fs/btrfs/reflink.c
> +++ b/fs/btrfs/reflink.c
> @@ -264,6 +264,7 @@ static int clone_copy_inline_extent(struct inode *dst,
> size);
> inode_add_bytes(dst, datal);
> set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &BTRFS_I(dst)->runtime_flags);
> + ret = btrfs_inode_set_file_extent_range(BTRFS_I(dst), 0, aligned_end);
> out:
> if (!ret && !trans) {
> /*
> --
> 2.11.0
>
