[PATCH 03/13] xfs: rationalise xfs_mount_wq users

[Dave Chinner]

On Tue, Sep 04, 2012 at 10:48:17AM -0500, Mark Tinguely wrote:
> On 08/30/12 07:00, Dave Chinner wrote:
> >-	/*
> >-	 * We shouldn't write/force the log if we are in the mount/unmount
> >-	 * process or on a read only filesystem. The workqueue still needs to be
> >-	 * active in both cases, however, because it is used for inode reclaim
> >-	 * during these times.  Use the MS_ACTIVE flag to avoid doing anything
> >-	 * during mount.  Doing work during unmount is avoided by calling
> >-	 * cancel_delayed_work_sync on this work queue before tearing down
> >-	 * the ail and the log in xfs_log_unmount.
> >-	 */
> >-	if (!(mp->m_super->s_flags&  MS_ACTIVE)&&
> >-	    !(mp->m_flags&  XFS_MOUNT_RDONLY)) {
> >+	if (!(mp->m_flags&  XFS_MOUNT_RDONLY)) {
> >  		/* dgc: errors ignored here */
> >  		if (mp->m_super->s_writers.frozen == SB_UNFROZEN&&
> >  		xfs_log_need_covered(mp))
> >@@ -408,8 +398,7 @@ xfs_sync_worker(
> >  		else
> >  			xfs_log_force(mp, 0);
> >
> >-		/* start pushing all the metadata that is currently
> >-		 * dirty */
> >+		/* start pushing all the metadata that is currently dirty */
> >  		xfs_ail_push_all(mp->m_ail);
> >  	}
> >
> 
> It appears that the removal of the MS_ACTIVE flag is causing the
> "atomic_read(&bp->b_hold)>  0," ASSERT.

I must be being slow today - I don't see why that would cause any
problems. The worker is not started at the end of the mount process
after everything is set up (i.e. just before MS_ACTIVE is removed),
and the worker is stopped before anything is torn down. That should
effectively replicate what the MS_ACTIVE flag is providing in the
old code.

Can you explain in more detail what lead you to this conclusion?

Cheers,

Dave.
-- 
Dave Chinner
david at fromorbit.com