Re: [PATCH 2/2] xfs: don't dirty snapshot logs for unlinked inode recovery

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Wed, Mar 07, 2018 at 05:33:48PM -0600, Eric Sandeen wrote:
> Now that unlinked inode recovery is done outside of
> log recovery, there is no need to dirty the log on
> snapshots just to handle unlinked inodes.  This means
> that readonly snapshots can be mounted without requiring
> -o ro,norecovery to avoid the log replay that can't happen
> on a readonly block device.
> 
> (unlinked inodes will just hang out in the agi buckets until
> the next writable mount)

FWIW I put these two in a test kernel to see what would happen and
generic/311 failures popped up.  It looked like the _check_scratch_fs
found incorrect block counts on the snapshot(?)

--D

> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> ---
> 
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 93588ea..5669525 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -1419,9 +1419,10 @@ struct proc_xfs_info {
>  
>  /*
>   * Second stage of a freeze. The data is already frozen so we only
> - * need to take care of the metadata. Once that's done sync the superblock
> - * to the log to dirty it in case of a crash while frozen. This ensures that we
> - * will recover the unlinked inode lists on the next mount.
> + * need to take care of the metadata.
> + * Any unlinked inode lists will remain at this point, and be recovered
> + * on the next writable mount if we crash while frozen, or create
> + * a snapshot from the frozen filesystem.
>   */
>  STATIC int
>  xfs_fs_freeze(
> @@ -1431,7 +1432,7 @@ struct proc_xfs_info {
>  
>  	xfs_save_resvblks(mp);
>  	xfs_quiesce_attr(mp);
> -	return xfs_sync_sb(mp, true);
> +	return 0;
>  }
>  
>  STATIC int
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html