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From: Ben Myers <bpm@sgi.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Nathan Scott <nathans@debian.org>, xfs@oss.sgi.com
Subject: Re: [PATCH] xfs_quota: remove calls to XFS_QSYNC
Date: Tue, 31 Jan 2012 10:26:17 -0600	[thread overview]
Message-ID: <20120131162617.GF7762@sgi.com> (raw)
In-Reply-To: <CAAp5ZgNKsY-OrWyDNU70KUKYCZUX_EvzngAvBsBTgrgkK6KyMA@mail.gmail.com>

On Tue, Jan 31, 2012 at 06:57:04AM +1100, Nathan Scott wrote:
> On 30 January 2012 22:50, Christoph Hellwig <hch@infradead.org> wrote:
> > ...
> > Nathan, I've cced you in case you still remember anything about this,
> > although it's fairly unlikely after 6.5 years.  Also if anyone at SGI
> > can find anything about the above commits in BugWorks additional feedback
> > would be welcome.
> 
> I can't recall - but usually there was greater detail in the bugworks entry,
> I think thats your best source now.
> 
> Patch looks OK to me FWIW, assuming nothing comes of the bugworks
> archeology exercise.

I'm not a ptools expert so I had to ask around.  This turned out to be

PV942815 - XFS quota reporting interacts badly with delalloc

"We get a constant trickle of confused people who've found that the used
space reported by repquota/quota does not get immediately updated after
creating new files / extending existing ones.  The problem is a result
of buffered IO in XFS doing delayed allocation - if we have not done an
allocation, the quota accounting has not been updated, so we end up with
effectively stale data being reported.

This affects CXFS too, of course.  After discussion a few weeks back on
the XFS conf. call, it was decided to not change CXFS (too expensive to
do a flush on all nodes) but that we can make some simple XFS changes to
make this less of a problem - i.e. flushing delalloc data just before we
extract quota information." -Nathan


Patch looks good to me.

Reviewed-by: Ben Myers <bpm@sgi.com>

-Ben

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  reply	other threads:[~2012-01-31 16:26 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-30 11:50 [PATCH] xfs_quota: remove calls to XFS_QSYNC Christoph Hellwig
2012-01-30 19:57 ` Nathan Scott
2012-01-31 16:26   ` Ben Myers [this message]
2012-01-31 21:01     ` Dave Chinner
2012-02-01 10:24       ` Christoph Hellwig

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