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=-16.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 CB868C47094 for ; Mon, 7 Jun 2021 22:25:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B3F6A61245 for ; Mon, 7 Jun 2021 22:25:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230375AbhFGW1f (ORCPT ); Mon, 7 Jun 2021 18:27:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:53986 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230183AbhFGW1f (ORCPT ); Mon, 7 Jun 2021 18:27:35 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id BD77F61040; Mon, 7 Jun 2021 22:25:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1623104743; bh=1dux238x4nCpTc/Ks1zNtPWbwcksk/ApfN3YPgywvcA=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=EeEl5S9CQNl2tHfDDLF0POXQb4X5g5kXhjDwd8Fag6k/PvZYZN3cMeWeAp5hLO3Pq zc7AhAjGzrMg9NmOkHSNtE2eRY6iehR7QwG5J1lAvFT4o5vIZzW+vneiV0ivXx9Ovs UbbsvlYB1OFBAVEexL2o565r4msAlv8JKMx89e9o6rnuRTabVkM/mnmPMaeiO4JUVd bQ3P8s2MqXgTylh7ml9mozqoE13+EOCs2G/HSqTfZT9zLVFN6rgSPc1CYPqn2wjsn0 M31wWqYJxzQBewHnu5z6H2YpzGJS9pt6Z0cnG66u6JqqBxAqX7CjfzGrUQ1EKI5vg1 mvtUe/CEM25wQ== Subject: [PATCH 9/9] xfs: avoid buffer deadlocks when walking fs inodes From: "Darrick J. Wong" To: djwong@kernel.org Cc: Dave Chinner , Christoph Hellwig , linux-xfs@vger.kernel.org, david@fromorbit.com, hch@infradead.org Date: Mon, 07 Jun 2021 15:25:43 -0700 Message-ID: <162310474347.3465262.15673658432859700796.stgit@locust> In-Reply-To: <162310469340.3465262.504398465311182657.stgit@locust> References: <162310469340.3465262.504398465311182657.stgit@locust> User-Agent: StGit/0.19 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org From: Darrick J. Wong When we're servicing an INUMBERS or BULKSTAT request or running quotacheck, grab an empty transaction so that we can use its inherent recursive buffer locking abilities to detect inode btree cycles without hitting ABBA buffer deadlocks. This patch requires the deferred inode inactivation patchset because xfs_irele cannot directly call xfs_inactive when the iwalk itself has an (empty) transaction. Found by fuzzing an inode btree pointer to introduce a cycle into the tree (xfs/365). Signed-off-by: Darrick J. Wong Reviewed-by: Dave Chinner Reviewed-by: Christoph Hellwig --- fs/xfs/xfs_itable.c | 42 +++++++++++++++++++++++++++++++++++++----- fs/xfs/xfs_iwalk.c | 33 ++++++++++++++++++++++++++++----- 2 files changed, 65 insertions(+), 10 deletions(-) diff --git a/fs/xfs/xfs_itable.c b/fs/xfs/xfs_itable.c index f331975a16de..84c17a9f9869 100644 --- a/fs/xfs/xfs_itable.c +++ b/fs/xfs/xfs_itable.c @@ -19,6 +19,7 @@ #include "xfs_error.h" #include "xfs_icache.h" #include "xfs_health.h" +#include "xfs_trans.h" /* * Bulk Stat @@ -163,6 +164,7 @@ xfs_bulkstat_one( .formatter = formatter, .breq = breq, }; + struct xfs_trans *tp; int error; if (breq->mnt_userns != &init_user_ns) { @@ -178,9 +180,18 @@ xfs_bulkstat_one( if (!bc.buf) return -ENOMEM; - error = xfs_bulkstat_one_int(breq->mp, breq->mnt_userns, NULL, - breq->startino, &bc); + /* + * Grab an empty transaction so that we can use its recursive buffer + * locking abilities to detect cycles in the inobt without deadlocking. + */ + error = xfs_trans_alloc_empty(breq->mp, &tp); + if (error) + goto out; + error = xfs_bulkstat_one_int(breq->mp, breq->mnt_userns, tp, + breq->startino, &bc); + xfs_trans_cancel(tp); +out: kmem_free(bc.buf); /* @@ -244,6 +255,7 @@ xfs_bulkstat( .formatter = formatter, .breq = breq, }; + struct xfs_trans *tp; int error; if (breq->mnt_userns != &init_user_ns) { @@ -259,9 +271,18 @@ xfs_bulkstat( if (!bc.buf) return -ENOMEM; - error = xfs_iwalk(breq->mp, NULL, breq->startino, breq->flags, + /* + * Grab an empty transaction so that we can use its recursive buffer + * locking abilities to detect cycles in the inobt without deadlocking. + */ + error = xfs_trans_alloc_empty(breq->mp, &tp); + if (error) + goto out; + + error = xfs_iwalk(breq->mp, tp, breq->startino, breq->flags, xfs_bulkstat_iwalk, breq->icount, &bc); - + xfs_trans_cancel(tp); +out: kmem_free(bc.buf); /* @@ -374,13 +395,24 @@ xfs_inumbers( .formatter = formatter, .breq = breq, }; + struct xfs_trans *tp; int error = 0; if (xfs_bulkstat_already_done(breq->mp, breq->startino)) return 0; - error = xfs_inobt_walk(breq->mp, NULL, breq->startino, breq->flags, + /* + * Grab an empty transaction so that we can use its recursive buffer + * locking abilities to detect cycles in the inobt without deadlocking. + */ + error = xfs_trans_alloc_empty(breq->mp, &tp); + if (error) + goto out; + + error = xfs_inobt_walk(breq->mp, tp, breq->startino, breq->flags, xfs_inumbers_walk, breq->icount, &ic); + xfs_trans_cancel(tp); +out: /* * We found some inode groups, so clear the error status and return diff --git a/fs/xfs/xfs_iwalk.c b/fs/xfs/xfs_iwalk.c index 917d51eefee3..7558486f4937 100644 --- a/fs/xfs/xfs_iwalk.c +++ b/fs/xfs/xfs_iwalk.c @@ -83,6 +83,9 @@ struct xfs_iwalk_ag { /* Skip empty inobt records? */ unsigned int skip_empty:1; + + /* Drop the (hopefully empty) transaction when calling iwalk_fn. */ + unsigned int drop_trans:1; }; /* @@ -352,7 +355,6 @@ xfs_iwalk_run_callbacks( int *has_more) { struct xfs_mount *mp = iwag->mp; - struct xfs_trans *tp = iwag->tp; struct xfs_inobt_rec_incore *irec; xfs_agino_t next_agino; int error; @@ -362,10 +364,15 @@ xfs_iwalk_run_callbacks( ASSERT(iwag->nr_recs > 0); /* Delete cursor but remember the last record we cached... */ - xfs_iwalk_del_inobt(tp, curpp, agi_bpp, 0); + xfs_iwalk_del_inobt(iwag->tp, curpp, agi_bpp, 0); irec = &iwag->recs[iwag->nr_recs - 1]; ASSERT(next_agino >= irec->ir_startino + XFS_INODES_PER_CHUNK); + if (iwag->drop_trans) { + xfs_trans_cancel(iwag->tp); + iwag->tp = NULL; + } + error = xfs_iwalk_ag_recs(iwag); if (error) return error; @@ -376,8 +383,15 @@ xfs_iwalk_run_callbacks( if (!has_more) return 0; + if (iwag->drop_trans) { + error = xfs_trans_alloc_empty(mp, &iwag->tp); + if (error) + return error; + } + /* ...and recreate the cursor just past where we left off. */ - error = xfs_inobt_cur(mp, tp, iwag->pag, XFS_BTNUM_INO, curpp, agi_bpp); + error = xfs_inobt_cur(mp, iwag->tp, iwag->pag, XFS_BTNUM_INO, curpp, + agi_bpp); if (error) return error; @@ -390,7 +404,6 @@ xfs_iwalk_ag( struct xfs_iwalk_ag *iwag) { struct xfs_mount *mp = iwag->mp; - struct xfs_trans *tp = iwag->tp; struct xfs_perag *pag = iwag->pag; struct xfs_buf *agi_bp = NULL; struct xfs_btree_cur *cur = NULL; @@ -469,7 +482,7 @@ xfs_iwalk_ag( error = xfs_iwalk_run_callbacks(iwag, &cur, &agi_bp, &has_more); out: - xfs_iwalk_del_inobt(tp, &cur, &agi_bp, error); + xfs_iwalk_del_inobt(iwag->tp, &cur, &agi_bp, error); return error; } @@ -599,8 +612,18 @@ xfs_iwalk_ag_work( error = xfs_iwalk_alloc(iwag); if (error) goto out; + /* + * Grab an empty transaction so that we can use its recursive buffer + * locking abilities to detect cycles in the inobt without deadlocking. + */ + error = xfs_trans_alloc_empty(mp, &iwag->tp); + if (error) + goto out; + iwag->drop_trans = 1; error = xfs_iwalk_ag(iwag); + if (iwag->tp) + xfs_trans_cancel(iwag->tp); xfs_iwalk_free(iwag); out: xfs_perag_put(iwag->pag);