[PATCH 03/11] xfs: fix efi/efd error handling to avoid fs shutdown hangs

[Dave Chinner]

On Fri, Aug 07, 2015 at 08:09:34AM -0400, Brian Foster wrote:
> On Fri, Aug 07, 2015 at 10:41:00AM +1000, Dave Chinner wrote:
> > On Thu, Aug 06, 2015 at 01:44:24PM -0400, Brian Foster wrote:
> > > diff --git a/fs/xfs/xfs_extfree_item.c b/fs/xfs/xfs_extfree_item.c
> > > index 42c9b05..aceb54f 100644
> > > --- a/fs/xfs/xfs_extfree_item.c
> > > +++ b/fs/xfs/xfs_extfree_item.c
> > > @@ -61,9 +61,15 @@ __xfs_efi_release(
> > >  
> > >  	if (atomic_dec_and_test(&efip->efi_refcount)) {
> > >  		spin_lock(&ailp->xa_lock);
> > > -		/* xfs_trans_ail_delete() drops the AIL lock. */
> > > -		xfs_trans_ail_delete(ailp, &efip->efi_item,
> > > -				     SHUTDOWN_LOG_IO_ERROR);
> > > +		/*
> > > +		 * We don't know whether the EFI made it to the AIL. Remove it
> > > +		 * if so. Note that xfs_trans_ail_delete() drops the AIL lock.
> > > +		 */
> > > +		if (efip->efi_item.li_flags & XFS_LI_IN_AIL)
> > > +			xfs_trans_ail_delete(ailp, &efip->efi_item,
> > > +					     SHUTDOWN_LOG_IO_ERROR);
> > > +		else
> > > +			spin_unlock(&ailp->xa_lock);
> > >  		xfs_efi_item_free(efip);
> > >  	}
> > 
> > We now have a lot of this pattern:
> > 
> > 	spin_lock(&ailp->xa_lock);
> > 	if (lip->li_flags & XFS_LI_IN_AIL)
> > 		xfs_trans_ail_delete(ailp, lip, shutdown_reason);
> > 	else
> > 		spin_unlock(&ailp->xa_lock);
> > 
> > occurring in the code. Can you look into adding a helper function
> > for this, say xfs_trans_ail_remove()? (separate patch, of course!)
> > 
> 
> There was only one other instance of this with regard to the EFI that is
> ultimately replaced with an xfs_efi_release() call. I'll look into
> whether there's enough instances of this for other items to justify a
> helper.

A quick look shows at least another 4 outside the EFI code:

xfs_buf_item_unlock
xfs_qm_dqflush_done
xfs_qm_dqflush
xfs_iflush_abort

That's enough for a helper, I think.

Cheers,

Dave.
-- 
Dave Chinner
david at fromorbit.com