diff mbox series

[v2,05/18] xfsprogs: Fix double unlock in defer capture code

Message ID 20220520190031.2198236-6-allison.henderson@oracle.com (mailing list archive)
State New, archived
Headers show
Series xfsprogs: Port larp, enable injects and log print for attri/d | expand

Commit Message

Allison Henderson May 20, 2022, 7 p.m. UTC 
Source kernel commit: 7b3ec2b20e44f579c022ad62243aa18c04c6addc

The new deferred attr patch set uncovered a double unlock in the
recent port of the defer ops capture and continue code.  During log
recovery, we're allowed to hold buffers to a transaction that's being
used to replay an intent item.  When we capture the resources as part
of scheduling a continuation of an intent chain, we call xfs_buf_hold
to retain our reference to the buffer beyond the transaction commit,
but we do /not/ call xfs_trans_bhold to maintain the buffer lock.
This means that xfs_defer_ops_continue needs to relock the buffers
before xfs_defer_restore_resources joins then tothe new transaction.

Additionally, the buffers should not be passed back via the dres
structure since they need to remain locked unlike the inodes.  So
simply set dr_bufs to zero after populating the dres structure.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Chandan Babu R <chandan.babu@oracle.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
---
 libxfs/xfs_defer.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/libxfs/xfs_defer.c b/libxfs/xfs_defer.c
index d654a7d9af82..3a2576c14ee9 100644
--- a/libxfs/xfs_defer.c
+++ b/libxfs/xfs_defer.c
@@ -776,17 +776,25 @@  xfs_defer_ops_continue(
 	struct xfs_trans		*tp,
 	struct xfs_defer_resources	*dres)
 {
+	unsigned int			i;
+
 	ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
 	ASSERT(!(tp->t_flags & XFS_TRANS_DIRTY));
 
-	/* Lock and join the captured inode to the new transaction. */
+	/* Lock the captured resources to the new transaction. */
 	if (dfc->dfc_held.dr_inos == 2)
 		xfs_lock_two_inodes(dfc->dfc_held.dr_ip[0], XFS_ILOCK_EXCL,
 				    dfc->dfc_held.dr_ip[1], XFS_ILOCK_EXCL);
 	else if (dfc->dfc_held.dr_inos == 1)
 		xfs_ilock(dfc->dfc_held.dr_ip[0], XFS_ILOCK_EXCL);
+
+	for (i = 0; i < dfc->dfc_held.dr_bufs; i++)
+		pthread_mutex_lock(&dfc->dfc_held.dr_bp[i]->b_lock);
+
+	/* Join the captured resources to the new transaction. */
 	xfs_defer_restore_resources(tp, &dfc->dfc_held);
 	memcpy(dres, &dfc->dfc_held, sizeof(struct xfs_defer_resources));
+	dres->dr_bufs = 0;
 
 	/* Move captured dfops chain and state to the transaction. */
 	list_splice_init(&dfc->dfc_dfops, &tp->t_dfops);