From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay3.corp.sgi.com [198.149.34.15]) by oss.sgi.com (Postfix) with ESMTP id DE5C17CA2 for ; Fri, 12 Feb 2016 20:33:18 -0600 (CST) Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by relay3.corp.sgi.com (Postfix) with ESMTP id 6E194AC002 for ; Fri, 12 Feb 2016 18:33:18 -0800 (PST) Received: from ipmail06.adl2.internode.on.net (ipmail06.adl2.internode.on.net [150.101.137.129]) by cuda.sgi.com with ESMTP id bDCuJJkyXw1kIOC4 for ; Fri, 12 Feb 2016 18:33:12 -0800 (PST) Date: Sat, 13 Feb 2016 13:33:10 +1100 From: Dave Chinner Subject: Re: block allocations for the refcount btree Message-ID: <20160213023310.GC14668@dastard> References: <20160210093011.GA19147@infradead.org> <20160210095010.GC23904@birch.djwong.org> <20160210190738.GA13051@infradead.org> <20160210214058.GN14668@dastard> <20160212191046.GA28421@infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20160212191046.GA28421@infradead.org> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Christoph Hellwig Cc: "Darrick J. Wong" , xfs@oss.sgi.com 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 _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs