Re: [PATCH v2 7/5] xfs: on failed mount, force-reclaim inodes after unmounting quota controls

[Dave Chinner <david@fromorbit.com>]

On Thu, Nov 09, 2017 at 03:57:48PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> When mounting fails, we must force-reclaim inodes (and disable delayed
> reclaim) /after/ the realtime and quota control have let go of the
> realtime and quota inodes.  Without this, we corrupt the timer list and
> cause other weird problems.
> 
> Found by xfs/376 fuzzing u3.bmbt[0].lastoff on an rmap filesystem to
> force a bogus post-eof extent reclaim that causes the fs to go down.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
> v2: try again with longer comment
> ---
>  fs/xfs/xfs_mount.c |   15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> index e9727d0..c879b51 100644
> --- a/fs/xfs/xfs_mount.c
> +++ b/fs/xfs/xfs_mount.c
> @@ -1022,10 +1022,21 @@ xfs_mountfs(
>  	xfs_rtunmount_inodes(mp);
>   out_rele_rip:
>  	IRELE(rip);
> -	cancel_delayed_work_sync(&mp->m_reclaim_work);
> -	xfs_reclaim_inodes(mp, SYNC_WAIT);
>  	/* Clean out dquots that might be in memory after quotacheck. */
>  	xfs_qm_unmount(mp);
> +	/*
> +	 * Cancel all delayed reclaim work and reclaim the inodes directly.
> +	 * We have to do this /after/ rtunmount and qm_unmount because those
> +	 * two will have scheduled delayed reclaim for the rt/quota inodes.
> +	 *
> +	 * This is slightly different from the unmountfs call sequence
> +	 * because we could be tearing down a partially set up mount.  In
> +	 * particular, if log_mount_finish fails we bail out without calling
> +	 * qm_unmount_quotas and therefore rely on qm_unmount to release the
> +	 * quota inodes.
> +	 */
> +	cancel_delayed_work_sync(&mp->m_reclaim_work);
> +	xfs_reclaim_inodes(mp, SYNC_WAIT);

Yup, that's better - I know what is going on now and I don't have to
remember the details. Double win! :P

Reviewed-by: Dave Chinner <dchinner@redhat.com>


-- 
Dave Chinner
david@fromorbit.com