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From: "Darrick J. Wong" <djwong@kernel.org>
To: djwong@kernel.org
Cc: linux-xfs@vger.kernel.org, hch@lst.de, dchinner@redhat.com,
	christian.brauner@ubuntu.com
Subject: [PATCH 2/3] xfs: avoid buffer deadlocks in inumbers/bulkstat
Date: Tue, 02 Mar 2021 14:28:28 -0800
Message-ID: <161472410813.3421449.1691962515820573818.stgit@magnolia> (raw)
In-Reply-To: <161472409643.3421449.2100229515469727212.stgit@magnolia>

From: Darrick J. Wong <djwong@kernel.org>

When we're servicing an INUMBERS or BULKSTAT request, grab an empty
transaction so that we don't hit an ABBA buffer deadlock if the inode
btree contains a cycle.

Found by fuzzing an inode btree pointer to introduce a cycle into the
tree (xfs/365).

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/xfs_itable.c |   46 ++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 42 insertions(+), 4 deletions(-)


diff --git a/fs/xfs/xfs_itable.c b/fs/xfs/xfs_itable.c
index ca310a125d1e..2339a1874efa 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
@@ -166,6 +167,7 @@ xfs_bulkstat_one(
 		.formatter	= formatter,
 		.breq		= breq,
 	};
+	struct xfs_trans	*tp;
 	int			error;
 
 	ASSERT(breq->icount == 1);
@@ -175,9 +177,20 @@ xfs_bulkstat_one(
 	if (!bc.buf)
 		return -ENOMEM;
 
+	/*
+	 * Grab freeze protection and allocate an empty transaction so that
+	 * we avoid deadlocking if the inobt is corrupt.
+	 */
+	sb_start_write(breq->mp->m_super);
+	error = xfs_trans_alloc_empty(breq->mp, &tp);
+	if (error)
+		goto out;
+
 	error = xfs_bulkstat_one_int(breq->mp, breq->mnt_userns, NULL,
 				     breq->startino, &bc);
-
+	xfs_trans_cancel(tp);
+out:
+	sb_end_write(breq->mp->m_super);
 	kmem_free(bc.buf);
 
 	/*
@@ -241,6 +254,7 @@ xfs_bulkstat(
 		.formatter	= formatter,
 		.breq		= breq,
 	};
+	struct xfs_trans	*tp;
 	int			error;
 
 	if (breq->mnt_userns != &init_user_ns) {
@@ -256,9 +270,20 @@ xfs_bulkstat(
 	if (!bc.buf)
 		return -ENOMEM;
 
-	error = xfs_iwalk(breq->mp, NULL, breq->startino, breq->flags,
+	/*
+	 * Grab freeze protection and allocate an empty transaction so that
+	 * we avoid deadlocking if the inobt is corrupt.
+	 */
+	sb_start_write(breq->mp->m_super);
+	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:
+	sb_end_write(breq->mp->m_super);
 	kmem_free(bc.buf);
 
 	/*
@@ -371,13 +396,26 @@ 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 freeze protection and allocate an empty transaction so that
+	 * we avoid deadlocking if the inobt is corrupt.
+	 */
+	sb_start_write(breq->mp->m_super);
+	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:
+	sb_end_write(breq->mp->m_super);
 
 	/*
 	 * We found some inode groups, so clear the error status and return


  parent reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-02 22:28 [PATCHSET 0/3] xfs: small fixes for 5.12 Darrick J. Wong
2021-03-02 22:28 ` [PATCH 1/3] xfs: fix quota accounting when a mount is idmapped Darrick J. Wong
2021-03-03  6:43   ` Christoph Hellwig
2021-03-03 14:44   ` Christian Brauner
2021-03-03 18:33     ` Darrick J. Wong
2021-03-03 19:09       ` Christian Brauner
2021-03-02 22:28 ` Darrick J. Wong [this message]
2021-03-03  6:45   ` [PATCH 2/3] xfs: avoid buffer deadlocks in inumbers/bulkstat Christoph Hellwig
2021-03-03 18:57     ` Darrick J. Wong
2021-03-02 22:28 ` [PATCH 3/3] xfs: force log and push AIL to clear pinned inodes when aborting mount Darrick J. Wong
2021-03-03  6:48   ` Christoph Hellwig
2021-03-03 19:02     ` Darrick J. Wong
2021-03-02 23:07 ` [PATCHSET 0/3] xfs: small fixes for 5.12 Christian Brauner

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