On Thu, Feb 11, 2016 at 08:40:58AM +1100, Dave Chinner wrote: > On Wed, Feb 10, 2016 at 11:07:38AM -0800, Christoph Hellwig wrote: > > On Wed, Feb 10, 2016 at 01:50:10AM -0800, Darrick J. Wong wrote: > > > That's odd... I'd have thought that the AG reservation would always be able > > > to handle a refcount btree expansion, since it calculates how many blocks > > > are needed to handle the worst case of 1 record per extent. There's also > > > a bug where we undercount the number of blocks already used, so it should > > > have an extra big reservation. > > > > > > OTOH I've seen occasional ENOSPCs in generic/186 and generic/168 too, so I > > > guess something's going wrong. Maybe the xfs_ag_resv* tracepoints can help? > > > > I'm not seeing an ENOSPC, I run into: > > > > [ 640.924891] XFS: Assertion failed: tp->t_blk_res_used <= tp->t_blk_res, file: fs/xfs/xfs_trans.c, line: 315 > > I run into that from time to time (maybe once a month) on a vanilla > kernel. > Any idea which test reproduces? I see that generic/033 resulted from the discussion below on the rfc. I don't currently reproduce with that test, however. The test mentions it uses fzero because zero range doesn't do writeback (comments ftw :) and thus allows splitting of delalloc extents, but it looks like that might no longer be the case in the kernel (since zero range was simplified to reuse punch/alloc). > 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 recall working on this, but not quite where it left off. If I dig back to my old tree from before the oss.sgi.com->vger switchover, I have a v1 branch for this work that was posted here: http://oss.sgi.com/archives/xfs/2014-10/msg00294.html It looks like we just never got it reviewed and I since lost track of it. I can resurrect it if warranted. I would like to nail down a current reproducer though... Brian > Cheers, > > Dave. > -- > Dave Chinner > david@xxxxxxxxxxxxx > > _______________________________________________ > xfs mailing list > xfs@xxxxxxxxxxx > http://oss.sgi.com/mailman/listinfo/xfs _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
