[3.16.y-ckt stable] Patch "ocfs2/dlm: fix BUG in dlm_move_lockres_to_recovery_list" has been added to the 3.16.y-ckt tree

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    ocfs2/dlm: fix BUG in dlm_move_lockres_to_recovery_list

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt27.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

---8<------------------------------------------------------------

>From 45258c744da52d2ef15800388aadc36c6963cf08 Mon Sep 17 00:00:00 2001
From: Joseph Qi <joseph.qi at huawei.com>
Date: Fri, 25 Mar 2016 14:21:29 -0700
Subject: ocfs2/dlm: fix BUG in dlm_move_lockres_to_recovery_list

commit be12b299a83fc807bbaccd2bcb8ec50cbb0cb55c upstream.

When master handles convert request, it queues ast first and then
returns status.  This may happen that the ast is sent before the request
status because the above two messages are sent by two threads.  And
right after the ast is sent, if master down, it may trigger BUG in
dlm_move_lockres_to_recovery_list in the requested node because ast
handler moves it to grant list without clear lock->convert_pending.  So
remove BUG_ON statement and check if the ast is processed in
dlmconvert_remote.

Signed-off-by: Joseph Qi <joseph.qi at huawei.com>
Reported-by: Yiwen Jiang <jiangyiwen at huawei.com>
Cc: Junxiao Bi <junxiao.bi at oracle.com>
Cc: Mark Fasheh <mfasheh at suse.de>
Cc: Joel Becker <jlbec at evilplan.org>
Cc: Tariq Saeed <tariq.x.saeed at oracle.com>
Cc: Junxiao Bi <junxiao.bi at oracle.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 fs/ocfs2/dlm/dlmconvert.c  | 13 +++++++++++++
 fs/ocfs2/dlm/dlmrecovery.c |  1 -
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/fs/ocfs2/dlm/dlmconvert.c b/fs/ocfs2/dlm/dlmconvert.c
index 84de55ed865a..f90931335c6b 100644
--- a/fs/ocfs2/dlm/dlmconvert.c
+++ b/fs/ocfs2/dlm/dlmconvert.c
@@ -288,6 +288,19 @@ enum dlm_status dlmconvert_remote(struct dlm_ctxt *dlm,
 		status = DLM_DENIED;
 		goto bail;
 	}
+
+	if (lock->ml.type == type && lock->ml.convert_type == LKM_IVMODE) {
+		mlog(0, "last convert request returned DLM_RECOVERING, but "
+		     "owner has already queued and sent ast to me. res %.*s, "
+		     "(cookie=%u:%llu, type=%d, conv=%d)\n",
+		     res->lockname.len, res->lockname.name,
+		     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+		     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
+		     lock->ml.type, lock->ml.convert_type);
+		status = DLM_NORMAL;
+		goto bail;
+	}
+
 	res->state |= DLM_LOCK_RES_IN_PROGRESS;
 	/* move lock to local convert queue */
 	/* do not alter lock refcount.  switching lists. */
diff --git a/fs/ocfs2/dlm/dlmrecovery.c b/fs/ocfs2/dlm/dlmrecovery.c
index 539b577740c7..44f93043b2e9 100644
--- a/fs/ocfs2/dlm/dlmrecovery.c
+++ b/fs/ocfs2/dlm/dlmrecovery.c
@@ -2053,7 +2053,6 @@ void dlm_move_lockres_to_recovery_list(struct dlm_ctxt *dlm,
 			dlm_lock_get(lock);
 			if (lock->convert_pending) {
 				/* move converting lock back to granted */
-				BUG_ON(i != DLM_CONVERTING_LIST);
 				mlog(0, "node died with convert pending "
 				     "on %.*s. move back to granted list.\n",
 				     res->lockname.len, res->lockname.name);