ocfs2/dlm: Take inflight reference count for remotely mastered resources too

The inflight reference count, in the lock resource, is taken to pin the resource
in memory. We take it when a new resource is created and release it after a
lock is attached to it. We do this to prevent the resource from getting purged
prematurely.

Earlier this reference count was being taken for locally mastered resources
only. This patch extends the same functionality for remotely mastered ones.

We are doing this because the same premature purging could occur for remotely
mastered resources if the remote node were to die before completion of the
create lock.

Fix for Oracle bug#12405575.

Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>

1 files changed, 7 insertions, 5 deletions

diff --git a/fs/ocfs2/dlm/dlmthread.c b/fs/ocfs2/dlm/dlmthread.c
index 4eff65e7e59e01..e73c833fc2a1a9 100644
--- a/fs/ocfs2/dlm/dlmthread.c
+++ b/fs/ocfs2/dlm/dlmthread.c
@@ -94,24 +94,26 @@ int __dlm_lockres_unused(struct dlm_lock_resource *res)
 {
 	int bit;
 
+	assert_spin_locked(&res->spinlock);
+
 	if (__dlm_lockres_has_locks(res))
 		return 0;
 
+	/* Locks are in the process of being created */
+	if (res->inflight_locks)
+		return 0;
+
 	if (!list_empty(&res->dirty) || res->state & DLM_LOCK_RES_DIRTY)
 		return 0;
 
 	if (res->state & DLM_LOCK_RES_RECOVERING)
 		return 0;
 
+	/* Another node has this resource with this node as the master */
 	bit = find_next_bit(res->refmap, O2NM_MAX_NODES, 0);
 	if (bit < O2NM_MAX_NODES)
 		return 0;
 
-	/*
-	 * since the bit for dlm->node_num is not set, inflight_locks better
-	 * be zero
-	 */
-	BUG_ON(res->inflight_locks != 0);
 	return 1;
 }