Re: [PATCH] Btrfs: fix wrong dentries after fsync of file that got its parent replaced

[David Sterba <dsterba@suse.cz>]

On Tue, Oct 09, 2018 at 03:05:29PM +0100, fdmanana@kernel.org wrote:
> From: Filipe Manana <fdmanana@suse.com>
> 
> In a scenario like the following:
> 
>   mkdir /mnt/A               # inode 258
>   mkdir /mnt/B               # inode 259
>   touch /mnt/B/bar           # inode 260
> 
>   sync
> 
>   mv /mnt/B/bar /mnt/A/bar
>   mv -T /mnt/A /mnt/B
>   fsync /mnt/B/bar
> 
>   <power fail>
> 
> After replaying the log we end up with file bar having 2 hard links, both
> with the name 'bar' and one in the directory with inode number 258 and the
> other in the directory with inode number 259. Also, we end up with the
> directory inode 259 still existing and with the directory inode 258 still
> named as 'A', instead of 'B'. In this scenario, file 'bar' should only
> have one hard link, located at directory inode 258, the directory inode
> 259 should not exist anymore and the name for directory inode 258 should
> be 'B'.
> 
> This incorrect behaviour happens because when attempting to log the old
> parents of an inode, we skip any parents that no longer exist. Fix this
> by forcing a full commit if an old parent no longer exists.
> 
> A test case for fstests follows soon.
> 
> Signed-off-by: Filipe Manana <fdmanana@suse.com>

Thanks, queued for 4.20 with CC: stable 4.4+ .