From: David Teigland <teigland@redhat.com>
Date: Thu, 5 Jun 2008 14:10:37 -0500
Subject: [dlm] reject normal unlock when lock waits on lookup
Message-id: 20080605191037.GJ18635@redhat.com
O-Subject: [RHEL5.3 PATCH 10/18] dlm: reject normal unlock when lock is waiting for lookup
Bugzilla: 450132
RH-Acked-by: Bob Peterson <rpeterso@redhat.com>

bz 450132  dlm: fixes for recovery of user lockspace

Fix bugs when userland apps using the dlm join/leave the lockspace,
causing recovery.

brew build including this patch
http://brewweb.devel.redhat.com/brew/taskinfo?taskID=1344633

upstream commit:

>From 42dc1601a9a31e8da767a4a9c37bad844b3698ab Mon Sep 17 00:00:00 2001
>From: David Teigland <teigland@redhat.com>
>Date: Wed, 9 Jan 2008 10:30:45 -0600
>Subject: [PATCH] dlm: reject normal unlock when lock is waiting for lookup

Non-forced unlocks should be rejected if the lock is waiting on the
rsb_lookup list for another lock to establish the master node.

Signed-off-by: David Teigland <teigland@redhat.com>

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index 40605a2..d515a49 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -2111,17 +2111,18 @@ static int validate_unlock_args(struct dlm_lkb *lkb, struct dlm_args *args)
 	/* an lkb may be waiting for an rsb lookup to complete where the
 	   lookup was initiated by another lock */
 
-	if (args->flags & (DLM_LKF_CANCEL | DLM_LKF_FORCEUNLOCK)) {
-		if (!list_empty(&lkb->lkb_rsb_lookup)) {
+	if (!list_empty(&lkb->lkb_rsb_lookup)) {
+		if (args->flags & (DLM_LKF_CANCEL | DLM_LKF_FORCEUNLOCK)) {
 			log_debug(ls, "unlock on rsb_lookup %x", lkb->lkb_id);
 			list_del_init(&lkb->lkb_rsb_lookup);
 			queue_cast(lkb->lkb_resource, lkb,
 				   args->flags & DLM_LKF_CANCEL ?
 				   -DLM_ECANCEL : -DLM_EUNLOCK);
 			unhold_lkb(lkb); /* undoes create_lkb() */
-			rv = -EBUSY;
-			goto out;
 		}
+		/* caller changes -EBUSY to 0 for CANCEL and FORCEUNLOCK */
+		rv = -EBUSY;
+		goto out;
 	}
 
 	/* cancel not allowed with another cancel/unlock in progress */