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Date:   Fri, 15 Nov 2019 08:53:50 +1100
From:   Dave Chinner <david@fromorbit.com>
To:     Brian Foster <bfoster@redhat.com>
Cc:     linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 26/28] xfs: use xfs_ail_push_all in xfs_reclaim_inodes
Message-ID: <20191114215350.GI4614@dread.disaster.area>
References: <20191031234618.15403-1-david@fromorbit.com>
 <20191031234618.15403-27-david@fromorbit.com>
 <20191106172215.GD37080@bfoster>
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On Wed, Nov 06, 2019 at 12:22:15PM -0500, Brian Foster wrote:
> On Fri, Nov 01, 2019 at 10:46:16AM +1100, Dave Chinner wrote:
> > From: Dave Chinner <dchinner@redhat.com>
> > 
> > If we are reclaiming all inodes, it is likely we need to flush the
> > entire AIL to do that. We have mechanisms to do that without needing
> > to push to a specific LSN.
> > 
> > Convert xfs_relaim_all_inodes() to use xfs_ail_push_all variant so
> > we can get rid of the hacky xfs_ail_push_sync() scaffolding we used
> > to support the intermediate stages of the non-blocking reclaim
> > changeset.
> > 
> > Signed-off-by: Dave Chinner <dchinner@redhat.com>
> > ---
> >  fs/xfs/xfs_icache.c     | 17 +++++++++++------
> >  fs/xfs/xfs_trans_ail.c  | 32 --------------------------------
> >  fs/xfs/xfs_trans_priv.h |  2 --
> >  3 files changed, 11 insertions(+), 40 deletions(-)
> > 
> > diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
> > index 71a729e29260..11bf4768d491 100644
> > --- a/fs/xfs/xfs_icache.c
> > +++ b/fs/xfs/xfs_icache.c
> ...
> > @@ -1066,13 +1074,10 @@ xfs_reclaim_all_inodes(
> >  				      xfs_inode_reclaim_isolate, &ra, to_free);
> >  		xfs_dispose_inodes(&ra.freeable);
> >  
> > -		if (freed == 0) {
> > +		if (freed == 0)
> >  			xfs_log_force(mp, XFS_LOG_SYNC);
> > -			xfs_ail_push_all(mp->m_ail);
> > -		} else if (ra.lowest_lsn != NULLCOMMITLSN) {
> > -			xfs_ail_push_sync(mp->m_ail, ra.lowest_lsn);
> > -		}
> > -		cond_resched();
> > +		else if (ra.dirty_skipped)
> > +			congestion_wait(BLK_RW_ASYNC, HZ/10);
> 
> Why not use xfs_ail_push_all_sync() in this function and skip the direct
> stall? This is only used in the unmount and quiesce paths so the big
> hammer approach seems reasonable.

Ok, that's a good simplification :)

-Dave.
-- 
Dave Chinner
david@fromorbit.com