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

David Sterba
2019-05-28T17:18:32Z

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.