dlm: Change rwlock which is only used in write mode to a spinlock

The ls_dirtbl[].lock was an rwlock, but since it was only used in write
mode a spinlock will suffice.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
diff --git a/fs/dlm/dir.c b/fs/dlm/dir.c
index 92969f8..858fba1 100644
--- a/fs/dlm/dir.c
+++ b/fs/dlm/dir.c
@@ -156,7 +156,7 @@
 
 	bucket = dir_hash(ls, name, namelen);
 
-	write_lock(&ls->ls_dirtbl[bucket].lock);
+	spin_lock(&ls->ls_dirtbl[bucket].lock);
 
 	de = search_bucket(ls, name, namelen, bucket);
 
@@ -173,7 +173,7 @@
 	list_del(&de->list);
 	kfree(de);
  out:
-	write_unlock(&ls->ls_dirtbl[bucket].lock);
+	spin_unlock(&ls->ls_dirtbl[bucket].lock);
 }
 
 void dlm_dir_clear(struct dlm_ls *ls)
@@ -185,14 +185,14 @@
 	DLM_ASSERT(list_empty(&ls->ls_recover_list), );
 
 	for (i = 0; i < ls->ls_dirtbl_size; i++) {
-		write_lock(&ls->ls_dirtbl[i].lock);
+		spin_lock(&ls->ls_dirtbl[i].lock);
 		head = &ls->ls_dirtbl[i].list;
 		while (!list_empty(head)) {
 			de = list_entry(head->next, struct dlm_direntry, list);
 			list_del(&de->list);
 			put_free_de(ls, de);
 		}
-		write_unlock(&ls->ls_dirtbl[i].lock);
+		spin_unlock(&ls->ls_dirtbl[i].lock);
 	}
 }
 
@@ -307,17 +307,17 @@
 
 	bucket = dir_hash(ls, name, namelen);
 
-	write_lock(&ls->ls_dirtbl[bucket].lock);
+	spin_lock(&ls->ls_dirtbl[bucket].lock);
 	de = search_bucket(ls, name, namelen, bucket);
 	if (de) {
 		*r_nodeid = de->master_nodeid;
-		write_unlock(&ls->ls_dirtbl[bucket].lock);
+		spin_unlock(&ls->ls_dirtbl[bucket].lock);
 		if (*r_nodeid == nodeid)
 			return -EEXIST;
 		return 0;
 	}
 
-	write_unlock(&ls->ls_dirtbl[bucket].lock);
+	spin_unlock(&ls->ls_dirtbl[bucket].lock);
 
 	if (namelen > DLM_RESNAME_MAXLEN)
 		return -EINVAL;
@@ -330,7 +330,7 @@
 	de->length = namelen;
 	memcpy(de->name, name, namelen);
 
-	write_lock(&ls->ls_dirtbl[bucket].lock);
+	spin_lock(&ls->ls_dirtbl[bucket].lock);
 	tmp = search_bucket(ls, name, namelen, bucket);
 	if (tmp) {
 		kfree(de);
@@ -339,7 +339,7 @@
 		list_add_tail(&de->list, &ls->ls_dirtbl[bucket].list);
 	}
 	*r_nodeid = de->master_nodeid;
-	write_unlock(&ls->ls_dirtbl[bucket].lock);
+	spin_unlock(&ls->ls_dirtbl[bucket].lock);
 	return 0;
 }