From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Fri, 19 Sep 2008 08:01:49 -0700 (PDT) Received: from cuda.sgi.com (cuda2.sgi.com [192.48.168.29]) by oss.sgi.com (8.12.11.20060308/8.12.11/SuSE Linux 0.7) with ESMTP id m8JF1jp4032672 for ; Fri, 19 Sep 2008 08:01:45 -0700 Received: from slurp.thebarn.com (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 5B65A45CE7E for ; Fri, 19 Sep 2008 08:03:17 -0700 (PDT) Received: from slurp.thebarn.com (cattelan-host202.dsl.visi.com [208.42.117.202]) by cuda.sgi.com with ESMTP id pnyZGqbBxEJ4gijC for ; Fri, 19 Sep 2008 08:03:17 -0700 (PDT) Message-ID: <48D3BF30.60508@thebarn.com> Date: Fri, 19 Sep 2008 08:03:12 -0700 From: Russell Cattelan MIME-Version: 1.0 Subject: Re: REVIEW: Fix for incore extent corruption. References: <48D19A83.4040608@thebarn.com> <48D1CD46.4010104@sgi.com> <48D1DCD5.7040502@thebarn.com> <48D218AE.9090400@sgi.com> <48D2C97A.1070703@thebarn.com> <63352.131.252.241.230.1221776406.squirrel@sandeen.net> <48D2F795.3080104@sgi.com> <48D31B9A.1080803@sgi.com> In-Reply-To: <48D31B9A.1080803@sgi.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: lachlan@sgi.com Cc: Eric Sandeen , xfs@oss.sgi.com Lachlan McIlroy wrote: > Here's a patch to remove xfs_iext_irec_compact_full() like Russell > did in his original patch - are you guys happy with this? > > I'm putting it through it's paces now and so far it looks good. I guess looking at my original patch it would have made sense to drop the call to xfs_iext_irec_irec_compact_pages/full in xfs_iext_indirect_to_direct or do what you did and keep the if else logic. So ya this look good. > > --- a/fs/xfs/xfs_inode.c 2008-09-19 13:08:08.000000000 +1000 > +++ b/fs/xfs/xfs_inode.c 2008-09-19 13:16:34.000000000 +1000 > @@ -4157,7 +4166,7 @@ xfs_iext_indirect_to_direct( > ASSERT(nextents <= XFS_LINEAR_EXTS); > size = nextents * sizeof(xfs_bmbt_rec_t); > > - xfs_iext_irec_compact_full(ifp); > + xfs_iext_irec_compact_pages(ifp); > ASSERT(ifp->if_real_bytes == XFS_IEXT_BUFSZ); > > ep = ifp->if_u1.if_ext_irec->er_extbuf; > @@ -4510,8 +4519,6 @@ xfs_iext_irec_compact( > xfs_iext_direct_to_inline(ifp, nextents); > } else if (nextents <= XFS_LINEAR_EXTS) { > xfs_iext_indirect_to_direct(ifp); > - } else if (nextents < (nlists * XFS_LINEAR_EXTS) >> 3) { > - xfs_iext_irec_compact_full(ifp); > } else if (nextents < (nlists * XFS_LINEAR_EXTS) >> 1) { > xfs_iext_irec_compact_pages(ifp); > } > @@ -4555,91 +4562,6 @@ xfs_iext_irec_compact_pages( > } > > /* > - * Fully compact the extent records managed by the indirection array. > - */ > -void > -xfs_iext_irec_compact_full( > - xfs_ifork_t *ifp) /* inode fork pointer */ > -{ > - xfs_bmbt_rec_host_t *ep, *ep_next; /* extent record pointers */ > - xfs_ext_irec_t *erp, *erp_next; /* extent irec pointers */ > - int erp_idx = 0; /* extent irec index */ > - int ext_avail; /* empty entries in ex list */ > - int ext_diff; /* number of exts to add */ > - int nlists; /* number of irec's (ex lists) */ > - > - ASSERT(ifp->if_flags & XFS_IFEXTIREC); > - > - nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ; > - erp = ifp->if_u1.if_ext_irec; > - ep = &erp->er_extbuf[erp->er_extcount]; > - erp_next = erp + 1; > - ep_next = erp_next->er_extbuf; > - > - while (erp_idx < nlists - 1) { > - /* > - * Check how many extent records are available in this irec. > - * If there is none skip the whole exercise. > - */ > - ext_avail = XFS_LINEAR_EXTS - erp->er_extcount; > - if (ext_avail) { > - > - /* > - * Copy over as many as possible extent records into > - * the previous page. > - */ > - ext_diff = MIN(ext_avail, erp_next->er_extcount); > - memcpy(ep, ep_next, ext_diff * sizeof(xfs_bmbt_rec_t)); > - erp->er_extcount += ext_diff; > - erp_next->er_extcount -= ext_diff; > - > - /* > - * If the next irec is empty now we can simply > - * remove it. > - */ > - if (erp_next->er_extcount == 0) { > - /* > - * Free page before removing extent record > - * so er_extoffs don't get modified in > - * xfs_iext_irec_remove. > - */ > - kmem_free(erp_next->er_extbuf); > - erp_next->er_extbuf = NULL; > - xfs_iext_irec_remove(ifp, erp_idx + 1); > - erp = &ifp->if_u1.if_ext_irec[erp_idx]; > - nlists = ifp->if_real_bytes / XFS_IEXT_BUFSZ; > - > - /* > - * If the next irec is not empty move up the content > - * that has not been copied to the previous page to > - * the beggining of this one. > - */ > - } else { > - memmove(erp_next->er_extbuf, &ep_next[ext_diff], > - erp_next->er_extcount * > - sizeof(xfs_bmbt_rec_t)); > - ep_next = erp_next->er_extbuf; > - memset(&ep_next[erp_next->er_extcount], 0, > - (XFS_LINEAR_EXTS - > - erp_next->er_extcount) * > - sizeof(xfs_bmbt_rec_t)); > - } > - } > - > - if (erp->er_extcount == XFS_LINEAR_EXTS) { > - erp_idx++; > - if (erp_idx < nlists) > - erp = &ifp->if_u1.if_ext_irec[erp_idx]; > - else > - break; > - } > - ep = &erp->er_extbuf[erp->er_extcount]; > - erp_next = erp + 1; > - ep_next = erp_next->er_extbuf; > - } > -} > - > -/* > * This is called to update the er_extoff field in the indirection > * array when extents have been added or removed from one of the > * extent lists. erp_idx contains the irec index to begin updating > > > Lachlan McIlroy wrote: >> Eric Sandeen wrote: >>> Russell Cattelan wrote: >>>> Lachlan McIlroy wrote: >>>>> Russell, this fixes xfs_iext_irec_compact_full(). If we don't move >>>>> all the records from the next page into the current page then we need >>>>> to update the er_extoff of the modified page as we move the remaining >>>>> extents up. Would you mind giving it a go? >>>>> >>>>> --- a/fs/xfs/xfs_inode.c 2008-09-18 18:48:46.000000000 +1000 >>>>> +++ b/fs/xfs/xfs_inode.c 2008-09-18 18:57:18.000000000 +1000 >>>>> @@ -4623,6 +4623,7 @@ xfs_iext_irec_compact_full( >>>>> (XFS_LINEAR_EXTS - >>>>> erp_next->er_extcount) * >>>>> sizeof(xfs_bmbt_rec_t)); >>>>> + erp_next->er_extoff += ext_diff; >>>>> } >>>>> } >>>>> >>>> Cool I'll give it some run through when I done traveling. >>>> >>>> I still think compact_full should simply be eliminated since >>>> it really doesn't help, and it's obviously confusing code. >>>> Or we should make sure it works and get rid of compact_pages >>>> since compact_full behaves just like compact_pages when not >>>> doing partial moves. >>> >>> I'd agree with that, at least as far as reevaluating this packing >>> stuff - >>> given the seriousness of the bug when you do hit it, and how rarely >>> it's >>> ever hit, apparently this chunk of code is almost never run .... >>> >> >> I agree too. If any code is difficult to reach it's also difficult >> to test. >> We've had numerous reports of extent corruption that could be >> explained by >> this bug but we have not been able to reproduce the symptoms let >> alone devise >> a reliable test case. >> >> What real benefit does compact_full have over compact_pages? >> Are there corner cases where compact_pages is not good enough? >> >> >> >> >