From: Dave Chinner <david@fromorbit.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>, xfs@oss.sgi.com
Subject: Re: block allocations for the refcount btree
Date: Sat, 13 Feb 2016 13:33:10 +1100 [thread overview]
Message-ID: <20160213023310.GC14668@dastard> (raw)
In-Reply-To: <20160212191046.GA28421@infradead.org>
On Fri, Feb 12, 2016 at 11:10:46AM -0800, Christoph Hellwig wrote:
> On Thu, Feb 11, 2016 at 08:40:58AM +1100, Dave Chinner wrote:
> > I run into that from time to time (maybe once a month) on a vanilla
> > kernel.
> >
> > IIRC, the problem is the delayed allocation extent split runs out of
> > it's reserved block count if you split it enough times. The case
> > I've seen is that the indlen calculated in xfs_bmap_worst_indlen()
> > ends up too small for a subsequent allocation after we've called
> > xfs_bmap_del_extent() to delete the middle of a delalloc extent too
> > many times.
> >
> > Brian had some patches that attempted to solve it - we may have
> > simply dropped the ball on this (again).
> >
> > http://oss.sgi.com/archives/xfs/2014-09/msg00337.html
>
> I'm pretty sure that is a separate issue. With the refcount btree we may
> allocate an extent (or rather just a single block) in xfs_alloc_ag_vextent
> as called from xfs_refcountbt_alloc_block. The reservation helps us to
> ensure this block is always available, but we still need to account for
> that in xfs_trans_reserve(), which we currently don't do for itruncate
> transactions.
Ok, so we may have two different issues with a similar failure
symptom. As it is, I don't think this is a show stopper - we're
expecting to find these sorts of issues as we go along (hence the
experimental tag on the feature) and I think, at this point, getting
review and an initial merge done is more important...
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2016-02-13 2:33 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-10 9:30 block allocations for the refcount btree Christoph Hellwig
2016-02-10 9:50 ` Darrick J. Wong
2016-02-10 19:07 ` Christoph Hellwig
2016-02-10 21:40 ` Dave Chinner
2016-02-11 14:09 ` Brian Foster
2016-02-11 20:21 ` Dave Chinner
2016-02-12 19:10 ` Christoph Hellwig
2016-02-13 2:33 ` Dave Chinner [this message]
2016-02-13 4:44 ` Darrick J. Wong
2016-02-13 8:02 ` Christoph Hellwig
2016-02-13 7:48 ` Christoph Hellwig
2016-02-14 0:21 ` Dave Chinner
2016-03-01 18:18 ` Darrick J. Wong
2016-03-01 20:40 ` Christoph Hellwig
2016-03-02 5:24 ` Darrick J. Wong
2016-03-02 9:59 ` Christoph Hellwig
2016-03-02 16:41 ` Darrick J. Wong
2016-03-02 16:57 ` Christoph Hellwig
2016-03-02 21:21 ` Darrick J. Wong
2016-03-03 14:05 ` Christoph Hellwig
2016-03-04 1:36 ` Darrick J. Wong
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