dlm: convert rsb list to rb_tree

Change the linked lists to rb_tree's in the rsb
hash table to speed up searches.  Slow rsb searches
were having a large impact on gfs2 performance due
to the large number of dlm locks gfs2 uses.

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

fs/dlm/debug_fs.c

@@ -393,6 +393,7 @@ static const struct seq_operations format3_seq_ops;
 
 static void *table_seq_start(struct seq_file *seq, loff_t *pos)
 {
+	struct rb_node *node;
 	struct dlm_ls *ls = seq->private;
 	struct rsbtbl_iter *ri;
 	struct dlm_rsb *r;
@@ -418,9 +419,10 @@ static void *table_seq_start(struct seq_file *seq, loff_t *pos)
 		ri->format = 3;
 
 	spin_lock(&ls->ls_rsbtbl[bucket].lock);
-	if (!list_empty(&ls->ls_rsbtbl[bucket].list)) {
-		list_for_each_entry(r, &ls->ls_rsbtbl[bucket].list,
-				    res_hashchain) {
+	if (!RB_EMPTY_ROOT(&ls->ls_rsbtbl[bucket].keep)) {
+		for (node = rb_first(&ls->ls_rsbtbl[bucket].keep); node;
+		     node = rb_next(node)) {
+			r = rb_entry(node, struct dlm_rsb, res_hashnode);
 			if (!entry--) {
 				dlm_hold_rsb(r);
 				ri->rsb = r;
@@ -449,9 +451,9 @@ static void *table_seq_start(struct seq_file *seq, loff_t *pos)
 		}
 
 		spin_lock(&ls->ls_rsbtbl[bucket].lock);
-		if (!list_empty(&ls->ls_rsbtbl[bucket].list)) {
-			r = list_first_entry(&ls->ls_rsbtbl[bucket].list,
-					     struct dlm_rsb, res_hashchain);
+		if (!RB_EMPTY_ROOT(&ls->ls_rsbtbl[bucket].keep)) {
+			node = rb_first(&ls->ls_rsbtbl[bucket].keep);
+			r = rb_entry(node, struct dlm_rsb, res_hashnode);
 			dlm_hold_rsb(r);
 			ri->rsb = r;
 			ri->bucket = bucket;
@@ -467,7 +469,7 @@ static void *table_seq_next(struct seq_file *seq, void *iter_ptr, loff_t *pos)
 {
 	struct dlm_ls *ls = seq->private;
 	struct rsbtbl_iter *ri = iter_ptr;
-	struct list_head *next;
+	struct rb_node *next;
 	struct dlm_rsb *r, *rp;
 	loff_t n = *pos;
 	unsigned bucket;
@@ -480,10 +482,10 @@ static void *table_seq_next(struct seq_file *seq, void *iter_ptr, loff_t *pos)
 
 	spin_lock(&ls->ls_rsbtbl[bucket].lock);
 	rp = ri->rsb;
-	next = rp->res_hashchain.next;
+	next = rb_next(&rp->res_hashnode);
 
-	if (next != &ls->ls_rsbtbl[bucket].list) {
-		r = list_entry(next, struct dlm_rsb, res_hashchain);
+	if (next) {
+		r = rb_entry(next, struct dlm_rsb, res_hashnode);
 		dlm_hold_rsb(r);
 		ri->rsb = r;
 		spin_unlock(&ls->ls_rsbtbl[bucket].lock);
@@ -511,9 +513,9 @@ static void *table_seq_next(struct seq_file *seq, void *iter_ptr, loff_t *pos)
 		}
 
 		spin_lock(&ls->ls_rsbtbl[bucket].lock);
-		if (!list_empty(&ls->ls_rsbtbl[bucket].list)) {
-			r = list_first_entry(&ls->ls_rsbtbl[bucket].list,
-					     struct dlm_rsb, res_hashchain);
+		if (!RB_EMPTY_ROOT(&ls->ls_rsbtbl[bucket].keep)) {
+			next = rb_first(&ls->ls_rsbtbl[bucket].keep);
+			r = rb_entry(next, struct dlm_rsb, res_hashnode);
 			dlm_hold_rsb(r);
 			ri->rsb = r;
 			ri->bucket = bucket;