On Fri, May 11, 2018 at 04:42:42PM +0100, fdmanana@xxxxxxxxxx wrote:
> From: Filipe Manana <fdmanana@xxxxxxxx>
>
> If a file has xattrs, we fsync it, to ensure we clear the flags
> BTRFS_INODE_NEEDS_FULL_SYNC and BTRFS_INODE_COPY_EVERYTHING from its
> inode, the current transaction commits and then we fsync it (without
> either of those bits being set in its inode), we end up not logging
> all its xattrs. This results in deleting all xattrs when replying the
> log after a power failure.
>
> Trivial reproducer
>
> $ mkfs.btrfs -f /dev/sdb
> $ mount /dev/sdb /mnt
>
> $ touch /mnt/foobar
> $ setfattr -n user.xa -v qwerty /mnt/foobar
> $ xfs_io -c "fsync" /mnt/foobar
>
> $ sync
>
> $ xfs_io -c "pwrite -S 0xab 0 64K" /mnt/foobar
> $ xfs_io -c "fsync" /mnt/foobar
> <power failure>
>
> $ mount /dev/sdb /mnt
> $ getfattr --absolute-names --dump /mnt/foobar
> <empty output>
> $
>
> So fix this by making sure all xattrs are logged if we log a file's inode
> item and neither the flags BTRFS_INODE_NEEDS_FULL_SYNC nor
> BTRFS_INODE_COPY_EVERYTHING were set in the inode.
>
> Fixes: 36283bf777d9 ("Btrfs: fix fsync xattr loss in the fast fsync path")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
Added to next, thanks, and I'll probably add that to 4.17-rc too.
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