From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8BBEDC433E1 for ; Tue, 16 Jun 2020 16:11:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6D8022151B for ; Tue, 16 Jun 2020 16:11:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="l/1nRAHn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731710AbgFPQLz (ORCPT ); Tue, 16 Jun 2020 12:11:55 -0400 Received: from aserp2120.oracle.com ([141.146.126.78]:36444 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731078AbgFPQLx (ORCPT ); Tue, 16 Jun 2020 12:11:53 -0400 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 05GG6rwL055757; Tue, 16 Jun 2020 16:11:47 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2020-01-29; bh=DIar1eQK2lzW0vIIjUygda1NQ7JNW/wFtpkqTwO3ZYw=; b=l/1nRAHnkUriGr9iTjumnkHPv2ako+k9tY3NcInb9B6492LmAqN0Dyd0avh0ChKDHi0s 1idWWTV1yBnpLY5oyFQHji9ScGJrcmOTJNaLA5CSO16eQUOfA0aReP5q68Hrceh+z5bJ cw5VHedS53BK1u0nyJEG5n0ogB8TrdTQDHXQnQNkWjgytS9lVeUJKTaUXLUOYyOeA8zx 4dkt3jdKKoRlf6uFaqJw4ksCYzxez3qNQ8Bh8V4rSNlnvauyNTImbMEyJ4hqsiWn6TJq rrWPx1726nzpq3P0q8TCTi9BDKcx4rSclDxav15K0HS/DrHgBZrJk4WetcE+rrg9w13m /Q== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by aserp2120.oracle.com with ESMTP id 31p6e7yrym-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 16 Jun 2020 16:11:46 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 05GG9DUH082636; Tue, 16 Jun 2020 16:11:46 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserp3020.oracle.com with ESMTP id 31p6dh1719-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 16 Jun 2020 16:11:46 +0000 Received: from abhmp0014.oracle.com (abhmp0014.oracle.com [141.146.116.20]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 05GGBj4p004898; Tue, 16 Jun 2020 16:11:45 GMT Received: from localhost (/67.169.218.210) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 16 Jun 2020 09:11:44 -0700 Date: Tue, 16 Jun 2020 09:11:43 -0700 From: "Darrick J. Wong" To: Gao Xiang Cc: linux-xfs@vger.kernel.org, Dave Chinner , Eric Sandeen Subject: Re: [RFC PATCH v3] xfs_repair: fix rebuilding btree block less than minrecs Message-ID: <20200616161143.GM11245@magnolia> References: <20200610035842.22785-1-hsiangkao@redhat.com> <20200610052624.7425-1-hsiangkao@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200610052624.7425-1-hsiangkao@redhat.com> X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9654 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=5 adultscore=0 bulkscore=0 phishscore=0 malwarescore=0 spamscore=0 mlxlogscore=999 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006160114 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9654 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 spamscore=0 impostorscore=0 bulkscore=0 clxscore=1015 malwarescore=0 suspectscore=5 mlxscore=0 phishscore=0 mlxlogscore=999 lowpriorityscore=0 cotscore=-2147483648 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006160114 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Wed, Jun 10, 2020 at 01:26:24PM +0800, Gao Xiang wrote: > In production, we found that sometimes xfs_repair phase 5 > rebuilds freespace node block with pointers less than minrecs > and if we trigger xfs_repair again it would report such > the following message: > > bad btree nrecs (39, min=40, max=80) in btbno block 0/7882 > > The background is that xfs_repair starts to rebuild AGFL > after the freespace btree is settled in phase 5 so we may > need to leave necessary room in advance for each btree > leaves in order to avoid freespace btree split and then > result in AGFL rebuild fails. The old mathematics uses > ceil(num_extents / maxrecs) to decide the number of node > blocks. That would be fine without leaving extra space > since minrecs = maxrecs / 2 but if some slack was decreased > from maxrecs, the result would be larger than what is > expected and cause num_recs_pb less than minrecs, i.e: > > num_extents = 79, adj_maxrecs = 80 - 2 (slack) = 78 > > so we'd get > > num_blocks = ceil(79 / 78) = 2, > num_recs_pb = 79 / 2 = 39, which is less than > minrecs = 80 / 2 = 40 > > OTOH, btree bulk loading code behaves in a different way. > As in xfs_btree_bload_level_geometry it wrote > > num_blocks = floor(num_extents / maxrecs) > > which will never go below minrecs. And when it goes above > maxrecs, just increment num_blocks and recalculate so we > can get the reasonable results. > > Later, btree bulk loader will replace the current repair code. > But we may still want to look for a backportable solution > for stable versions. Hence, keep the same logic to avoid > the freespace as well as rmap btree minrecs underflow for now. > > Cc: "Darrick J. Wong" > Cc: Dave Chinner > Cc: Eric Sandeen > Fixes: 9851fd79bfb1 ("repair: AGFL rebuild fails if btree split required") > Signed-off-by: Gao Xiang > --- > changes since v2: > still some minor styling fix (ASSERT, args).. > > changes since v1: > - fix indentation, typedefs, etc code styling problem > pointed out by Darrick; > > - adapt init_rmapbt_cursor to the new algorithm since > it's similar pointed out by Darrick; thus the function > name remains the origin compute_level_geometry... > and hence, adjust the subject a bit as well. > > repair/phase5.c | 152 ++++++++++++++++++++---------------------------- > 1 file changed, 63 insertions(+), 89 deletions(-) > > diff --git a/repair/phase5.c b/repair/phase5.c > index abae8a08..d30d32b2 100644 > --- a/repair/phase5.c > +++ b/repair/phase5.c > @@ -348,11 +348,32 @@ finish_cursor(bt_status_t *curs) > * failure at runtime. Hence leave a couple of records slack space in > * each block to allow immediate modification of the tree without > * requiring splits to be done. > - * > - * XXX(hch): any reason we don't just look at mp->m_alloc_mxr? > */ > -#define XR_ALLOC_BLOCK_MAXRECS(mp, level) \ > - (libxfs_allocbt_maxrecs((mp), (mp)->m_sb.sb_blocksize, (level) == 0) - 2) > +static void > +compute_level_geometry( > + struct xfs_mount *mp, > + struct bt_stat_level *lptr, > + uint64_t nr_this_level, Probably didn't need a u64 here, but that's probably just my kernel-coloured glasses. :) > + int slack, > + bool leaf) > +{ > + unsigned int maxrecs = mp->m_alloc_mxr[!leaf]; > + unsigned int desired_npb; > + > + desired_npb = max(mp->m_alloc_mnr[!leaf], maxrecs - slack); > + lptr->num_recs_tot = nr_this_level; > + lptr->num_blocks = max(1ULL, nr_this_level / desired_npb); > + > + lptr->num_recs_pb = nr_this_level / lptr->num_blocks; > + lptr->modulo = nr_this_level % lptr->num_blocks; > + if (lptr->num_recs_pb > maxrecs || > + (lptr->num_recs_pb == maxrecs && lptr->modulo)) { > + lptr->num_blocks++; > + > + lptr->num_recs_pb = nr_this_level / lptr->num_blocks; > + lptr->modulo = nr_this_level % lptr->num_blocks; > + } Seems to be more or less the same solution that I (half unknowingly) coded into the btree bulkload geometry calculator, so: Reviewed-by: Darrick J. Wong (Still working on adapting the new phase5 code to try to fill the AGFL as part of rebuilding the free space btrees, fwiw.) --D > +} > > /* > * this calculates a freespace cursor for an ag. > @@ -370,6 +391,7 @@ calculate_freespace_cursor(xfs_mount_t *mp, xfs_agnumber_t agno, > int i; > int extents_used; > int extra_blocks; > + uint64_t old_blocks; > bt_stat_level_t *lptr; > bt_stat_level_t *p_lptr; > extent_tree_node_t *ext_ptr; > @@ -388,10 +410,7 @@ calculate_freespace_cursor(xfs_mount_t *mp, xfs_agnumber_t agno, > * of the tree and set up the cursor for the leaf level > * (note that the same code is duplicated further down) > */ > - lptr->num_blocks = howmany(num_extents, XR_ALLOC_BLOCK_MAXRECS(mp, 0)); > - lptr->num_recs_pb = num_extents / lptr->num_blocks; > - lptr->modulo = num_extents % lptr->num_blocks; > - lptr->num_recs_tot = num_extents; > + compute_level_geometry(mp, lptr, num_extents, 2, true); > level = 1; > > #ifdef XR_BLD_FREE_TRACE > @@ -405,30 +424,23 @@ calculate_freespace_cursor(xfs_mount_t *mp, xfs_agnumber_t agno, > * if we need more levels, set them up. # of records > * per level is the # of blocks in the level below it > */ > - if (lptr->num_blocks > 1) { > - for (; btree_curs->level[level - 1].num_blocks > 1 > - && level < XFS_BTREE_MAXLEVELS; > - level++) { > - lptr = &btree_curs->level[level]; > - p_lptr = &btree_curs->level[level - 1]; > - lptr->num_blocks = howmany(p_lptr->num_blocks, > - XR_ALLOC_BLOCK_MAXRECS(mp, level)); > - lptr->modulo = p_lptr->num_blocks > - % lptr->num_blocks; > - lptr->num_recs_pb = p_lptr->num_blocks > - / lptr->num_blocks; > - lptr->num_recs_tot = p_lptr->num_blocks; > + while (lptr->num_blocks > 1) { > + p_lptr = lptr; > + lptr = &btree_curs->level[level]; > + > + compute_level_geometry(mp, lptr, > + p_lptr->num_blocks, 0, false); > #ifdef XR_BLD_FREE_TRACE > - fprintf(stderr, "%s %d %d %d %d %d\n", __func__, > - level, > - lptr->num_blocks, > - lptr->num_recs_pb, > - lptr->modulo, > - lptr->num_recs_tot); > + fprintf(stderr, "%s %d %d %d %d %d\n", __func__, > + level, > + lptr->num_blocks, > + lptr->num_recs_pb, > + lptr->modulo, > + lptr->num_recs_tot); > #endif > - } > + level++; > } > - > + ASSERT(level < XFS_BTREE_MAXLEVELS); > ASSERT(lptr->num_blocks == 1); > btree_curs->num_levels = level; > > @@ -496,8 +508,11 @@ calculate_freespace_cursor(xfs_mount_t *mp, xfs_agnumber_t agno, > * see if the number of leaf blocks will change as a result > * of the number of extents changing > */ > - if (howmany(num_extents, XR_ALLOC_BLOCK_MAXRECS(mp, 0)) > - != btree_curs->level[0].num_blocks) { > + old_blocks = btree_curs->level[0].num_blocks; > + compute_level_geometry(mp, &btree_curs->level[0], num_extents, 2, true); > + extra_blocks = 0; > + > + if (old_blocks != btree_curs->level[0].num_blocks) { > /* > * yes -- recalculate the cursor. If the number of > * excess (overallocated) blocks is < xfs_agfl_size/2, we're ok. > @@ -553,31 +568,19 @@ calculate_freespace_cursor(xfs_mount_t *mp, xfs_agnumber_t agno, > } > > lptr = &btree_curs->level[0]; > - lptr->num_blocks = howmany(num_extents, > - XR_ALLOC_BLOCK_MAXRECS(mp, 0)); > - lptr->num_recs_pb = num_extents / lptr->num_blocks; > - lptr->modulo = num_extents % lptr->num_blocks; > - lptr->num_recs_tot = num_extents; > level = 1; > > /* > * if we need more levels, set them up > */ > - if (lptr->num_blocks > 1) { > - for (level = 1; btree_curs->level[level-1].num_blocks > - > 1 && level < XFS_BTREE_MAXLEVELS; > - level++) { > - lptr = &btree_curs->level[level]; > - p_lptr = &btree_curs->level[level-1]; > - lptr->num_blocks = howmany(p_lptr->num_blocks, > - XR_ALLOC_BLOCK_MAXRECS(mp, level)); > - lptr->modulo = p_lptr->num_blocks > - % lptr->num_blocks; > - lptr->num_recs_pb = p_lptr->num_blocks > - / lptr->num_blocks; > - lptr->num_recs_tot = p_lptr->num_blocks; > - } > + while (lptr->num_blocks > 1) { > + p_lptr = lptr; > + lptr = &btree_curs->level[level++]; > + > + compute_level_geometry(mp, lptr, > + p_lptr->num_blocks, 0, false); > } > + ASSERT(level < XFS_BTREE_MAXLEVELS); > ASSERT(lptr->num_blocks == 1); > btree_curs->num_levels = level; > > @@ -591,22 +594,6 @@ calculate_freespace_cursor(xfs_mount_t *mp, xfs_agnumber_t agno, > > ASSERT(blocks_allocated_total >= blocks_needed); > extra_blocks = blocks_allocated_total - blocks_needed; > - } else { > - if (extents_used > 0) { > - /* > - * reset the leaf level geometry to account > - * for consumed extents. we can leave the > - * rest of the cursor alone since the number > - * of leaf blocks hasn't changed. > - */ > - lptr = &btree_curs->level[0]; > - > - lptr->num_recs_pb = num_extents / lptr->num_blocks; > - lptr->modulo = num_extents % lptr->num_blocks; > - lptr->num_recs_tot = num_extents; > - } > - > - extra_blocks = 0; > } > > btree_curs->num_tot_blocks = blocks_allocated_pt; > @@ -1376,7 +1363,6 @@ init_rmapbt_cursor( > struct bt_stat_level *lptr; > struct bt_stat_level *p_lptr; > xfs_extlen_t blocks_allocated; > - int maxrecs; > > if (!xfs_sb_version_hasrmapbt(&mp->m_sb)) { > memset(btree_curs, 0, sizeof(struct bt_status)); > @@ -1412,32 +1398,20 @@ init_rmapbt_cursor( > * Leave enough slack in the rmapbt that we can insert the > * metadata AG entries without too many splits. > */ > - maxrecs = mp->m_rmap_mxr[0]; > - if (num_recs > maxrecs) > - maxrecs -= 10; > - blocks_allocated = lptr->num_blocks = howmany(num_recs, maxrecs); > - > - lptr->modulo = num_recs % lptr->num_blocks; > - lptr->num_recs_pb = num_recs / lptr->num_blocks; > - lptr->num_recs_tot = num_recs; > + compute_level_geometry(mp, lptr, num_recs, > + num_recs > mp->m_rmap_mxr[0] ? 10 : 0, true); > + blocks_allocated = lptr->num_blocks; > level = 1; > > - if (lptr->num_blocks > 1) { > - for (; btree_curs->level[level-1].num_blocks > 1 > - && level < XFS_BTREE_MAXLEVELS; > - level++) { > - lptr = &btree_curs->level[level]; > - p_lptr = &btree_curs->level[level - 1]; > - lptr->num_blocks = howmany(p_lptr->num_blocks, > - mp->m_rmap_mxr[1]); > - lptr->modulo = p_lptr->num_blocks % lptr->num_blocks; > - lptr->num_recs_pb = p_lptr->num_blocks > - / lptr->num_blocks; > - lptr->num_recs_tot = p_lptr->num_blocks; > + while (lptr->num_blocks > 1) { > + p_lptr = lptr; > + lptr = &btree_curs->level[level++]; > > - blocks_allocated += lptr->num_blocks; > - } > + compute_level_geometry(mp, lptr, > + p_lptr->num_blocks, 0, false); > + blocks_allocated += lptr->num_blocks; > } > + ASSERT(level < XFS_BTREE_MAXLEVELS); > ASSERT(lptr->num_blocks == 1); > btree_curs->num_levels = level; > > -- > 2.18.1 >