ocfs2/dlm: move lock to the tail of grant queue while doing in-place convert

From: xuejiufei <[email protected]>
Subject: ocfs2/dlm: move lock to the tail of grant queue while doing in-place convert

We have found a bug when two nodes doing umount one after another.

1) Node 1 migrate a lockres that has 3 locks in grant queue such as N2(PR)<->N3(NL)<->N4(PR) to N2. After migration, lvb of the lock N3(NL) and N4(PR) are empty on node 2 because migration target do not copy lvb to these two lock.

2) Node 3 want to convert to PR, it can be granted in __dlmconvert_master(), and the order of these locks is unchanged. The lvb of the lock N3(PR) on node 2 is copyed from lockres in function dlm_update_lvb() while the lvb of lock N4(PR) is still empty.

3) Node 2 want to leave domain, it will migrate this lockres to node 3. Then node 2 will trigger the BUG in dlm_prepare_lvb_for_migration() when adding the lock N4(PR) to mres with the following message because the lvb of mres is already copied from lock N3(PR), but the lvb of lock N4(PR) is empty.

"Mismatched lvb in lock cookie=%u:%llu, name=%.*s, node=%u"

[akpm at linux-foundation.org: tweak comment]

Signed-off-by xuejiufei <[email protected]>

Cc Mark Fasheh <[email protected]>

Cc Joel Becker <[email protected]>

Cc Junxiao Bi <[email protected]>

Cc Joseph Qi <[email protected]>

Signed-off-by Andrew Morton <[email protected]>

---

 fs/ocfs2/dlm/dlmconvert.c |    6 ++++++
 1 file changed, 6 insertions(+)

diff -puN fs/ocfs2/dlm/dlmconvert.c~ocfs2-dlm-move-lock-to-the-tail-of-grant-queue-while-doing-in-place-convert fs/ocfs2/dlm/dlmconvert.c

fs/ocfs2/dlm/dlmconvert.c renamed from fs/ocfs2/dlm/dlmconvert.c~ocfs2-dlm-move-lock-to-the-tail-of-grant-queue-while-doing-in-place-convert +6 -0

@@ -212,6 +212,12 @@ grant:
 	if (lock->lksb->flags & DLM_LKSB_PUT_LVB)
 		memcpy(res->lvb, lock->lksb->lvb, DLM_LVB_LEN);
 
+	/*
+	 * Move the lock to the tail because it may be the only lock which has
+	 * an invalid lvb.
+	 */
+	list_move_tail(&lock->list, &res->granted);
+
 	status = DLM_NORMAL;
 	*call_ast = 1;
 	goto unlock_exit;

_

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