Re: [PATCH 2/3] Btrfs: fix wrong ctime and mtime of a directory after log replay

[David Sterba <dsterba@suse.cz>]

On Wed, May 15, 2019 at 04:02:47PM +0100, fdmanana@kernel.org wrote:
> From: Filipe Manana <fdmanana@suse.com>
> 
> When replaying a log that contains a new file or directory name that needs
> to be added to its parent directory, we end up updating the mtime and the
> ctime of the parent directory to the current time after we have set their
> values to the correct ones (set at fsync time), efectivelly losing them.
> 
> Sample reproducer:
> 
>   $ mkfs.btrfs -f /dev/sdb
>   $ mount /dev/sdb /mnt
> 
>   $ mkdir /mnt/dir
>   $ touch /mnt/dir/file
> 
>   # fsync of the directory is optional, not needed
>   $ xfs_io -c fsync /mnt/dir
>   $ xfs_io -c fsync /mnt/dir/file
> 
>   $ stat -c %Y /mnt/dir
>   1557856079
> 
>   <power failure>
> 
>   $ sleep 3
>   $ mount /dev/sdb /mnt
>   $ stat -c %Y /mnt/dir
>   1557856082
> 
>     --> should have been 1557856079, the mtime is updated to the current
>         time when replaying the log
> 
> Fix this by not updating the mtime and ctime to the current time at
> btrfs_add_link() when we are replaying a log tree.
> 
> This could be triggered by my recent fsync fuzz tester for fstests, for
> which an fstests patch exists titled "fstests: generic, fsync fuzz tester
> with fsstress".
> 
> Fixes: e02119d5a7b43 ("Btrfs: Add a write ahead tree log to optimize synchronous operations")
> Signed-off-by: Filipe Manana <fdmanana@suse.com>

Added to 5.2-rc queue, thanks.