Re: [PATCH] xfs: update superblock counters correctly for !lazysbcount

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Tue, Apr 27, 2021 at 08:46:25AM -0400, Brian Foster wrote:
> On Tue, Apr 27, 2021 at 09:12:01AM +0800, Gao Xiang wrote:
> > From: Dave Chinner <dchinner@xxxxxxxxxx>
> > 
> > Keep the mount superblock counters up to date for !lazysbcount
> > filesystems so that when we log the superblock they do not need
> > updating in any way because they are already correct.
> > 
> > It's found by what Zorro reported:
> > 1. mkfs.xfs -f -l lazy-count=0 -m crc=0 $dev
> > 2. mount $dev $mnt
> > 3. fsstress -d $mnt -p 100 -n 1000 (maybe need more or less io load)
> > 4. umount $mnt
> > 5. xfs_repair -n $dev
> > and I've seen no problem with this patch.
> > 
> > Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> > Reported-by: Zorro Lang <zlang@xxxxxxxxxx>
> > Reviewed-by: Gao Xiang <hsiangkao@xxxxxxxxxx>
> > Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxx>
> > ---
> 
> Could you provide a bit more detail on the problem in the commit log?
> From the description and code change, it seems like there is some
> problem with doing the percpu aggregation in xfs_log_sb() on
> !lazysbcount filesystems. Therefore this patch reserves that behavior
> for lazysbcount, and instead enables per-transaction updates in the
> !lazysbcount specific cleanup path. Am I following that correctly?

This patch inherited from Dave's patch [1] (and I added reproduable
steps),
https://lore.kernel.org/r/20210422014446.GZ63242@xxxxxxxxxxxxxxxxxxx

More details see my original patch v2:
https://lore.kernel.org/r/20210420110855.2961626-1-hsiangkao@xxxxxxxxxx

Thanks,
Gao Xiang

> 
> Brian
> 
> > 
> > As per discussion earilier [1], use the way Dave suggested instead.
> > Also update the line to
> > 	mp->m_sb.sb_fdblocks += tp->t_fdblocks_delta + tp->t_res_fdblocks_delta;
> > so it can fix the case above.
> > 
> > with XFS debug off, xfstests auto testcases fail on my loop-device-based
> > testbed with this patch and Darrick's [2]:
> > 
> > generic/095 generic/300 generic/600 generic/607 xfs/073 xfs/148 xfs/273
> > xfs/293 xfs/491 xfs/492 xfs/495 xfs/503 xfs/505 xfs/506 xfs/514 xfs/515
> > 
> > MKFS_OPTIONS="-mcrc=0 -llazy-count=0"
> > 
> > and these testcases above still fail without these patches or with
> > XFS debug on, so I've seen no regression due to this patch.
> > 
> > [1] https://lore.kernel.org/r/20210422030102.GA63242@xxxxxxxxxxxxxxxxxxx/
> > [2] https://lore.kernel.org/r/20210425154634.GZ3122264@magnolia/
> > 
> >  fs/xfs/libxfs/xfs_sb.c | 16 +++++++++++++---
> >  fs/xfs/xfs_trans.c     |  3 +++
> >  2 files changed, 16 insertions(+), 3 deletions(-)
> > 
> > diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
> > index 60e6d255e5e2..dfbbcbd448c1 100644
> > --- a/fs/xfs/libxfs/xfs_sb.c
> > +++ b/fs/xfs/libxfs/xfs_sb.c
> > @@ -926,9 +926,19 @@ xfs_log_sb(
> >  	struct xfs_mount	*mp = tp->t_mountp;
> >  	struct xfs_buf		*bp = xfs_trans_getsb(tp);
> >  
> > -	mp->m_sb.sb_icount = percpu_counter_sum(&mp->m_icount);
> > -	mp->m_sb.sb_ifree = percpu_counter_sum(&mp->m_ifree);
> > -	mp->m_sb.sb_fdblocks = percpu_counter_sum(&mp->m_fdblocks);
> > +	/*
> > +	 * Lazy sb counters don't update the in-core superblock so do that now.
> > +	 * If this is at unmount, the counters will be exactly correct, but at
> > +	 * any other time they will only be ballpark correct because of
> > +	 * reservations that have been taken out percpu counters. If we have an
> > +	 * unclean shutdown, this will be corrected by log recovery rebuilding
> > +	 * the counters from the AGF block counts.
> > +	 */
> > +	if (xfs_sb_version_haslazysbcount(&mp->m_sb)) {
> > +		mp->m_sb.sb_icount = percpu_counter_sum(&mp->m_icount);
> > +		mp->m_sb.sb_ifree = percpu_counter_sum(&mp->m_ifree);
> > +		mp->m_sb.sb_fdblocks = percpu_counter_sum(&mp->m_fdblocks);
> > +	}
> >  
> >  	xfs_sb_to_disk(bp->b_addr, &mp->m_sb);
> >  	xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SB_BUF);
> > diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
> > index bcc978011869..1e37aa8eca5a 100644
> > --- a/fs/xfs/xfs_trans.c
> > +++ b/fs/xfs/xfs_trans.c
> > @@ -629,6 +629,9 @@ xfs_trans_unreserve_and_mod_sb(
> >  
> >  	/* apply remaining deltas */
> >  	spin_lock(&mp->m_sb_lock);
> > +	mp->m_sb.sb_fdblocks += tp->t_fdblocks_delta + tp->t_res_fdblocks_delta;
> > +	mp->m_sb.sb_icount += idelta;
> > +	mp->m_sb.sb_ifree += ifreedelta;
> >  	mp->m_sb.sb_frextents += rtxdelta;
> >  	mp->m_sb.sb_dblocks += tp->t_dblocks_delta;
> >  	mp->m_sb.sb_agcount += tp->t_agcount_delta;
> > -- 
> > 2.27.0
> > 
> 




[Index of Archives]     [XFS Filesystem Development (older mail)]     [Linux Filesystem Development]     [Linux Audio Users]     [Yosemite Trails]     [Linux Kernel]     [Linux RAID]     [Linux SCSI]


  Powered by Linux