dlm: fix slow rsb search in dir recovery

The function used to find an rsb during directory
recovery was searching the single linear list of
rsb's.  This wasted a lot of time compared to
using the standard hash table to find the rsb.
Signed-off-by: David Teigland <teigland@redhat.com>

fs/dlm/dir.c

@@ -351,11 +351,28 @@ int dlm_dir_lookup(struct dlm_ls *ls, int nodeid, char *name, int namelen,
 static struct dlm_rsb *find_rsb_root(struct dlm_ls *ls, char *name, int len)
 {
 	struct dlm_rsb *r;
+	uint32_t hash, bucket;
+	int rv;
+
+	hash = jhash(name, len, 0);
+	bucket = hash & (ls->ls_rsbtbl_size - 1);
+
+	spin_lock(&ls->ls_rsbtbl[bucket].lock);
+	rv = dlm_search_rsb_tree(&ls->ls_rsbtbl[bucket].keep, name, len, 0, &r);
+	if (rv)
+		rv = dlm_search_rsb_tree(&ls->ls_rsbtbl[bucket].toss,
+					 name, len, 0, &r);
+	spin_unlock(&ls->ls_rsbtbl[bucket].lock);
+
+	if (!rv)
+		return r;
 
 	down_read(&ls->ls_root_sem);
 	list_for_each_entry(r, &ls->ls_root_list, res_root_list) {
 		if (len == r->res_length && !memcmp(name, r->res_name, len)) {
 			up_read(&ls->ls_root_sem);
+			log_error(ls, "find_rsb_root revert to root_list %s",
+				  r->res_name);
 			return r;
 		}
 	}

fs/dlm/lock.c

@@ -411,8 +411,8 @@ static int rsb_cmp(struct dlm_rsb *r, const char *name, int nlen)
 	return memcmp(r->res_name, maxname, DLM_RESNAME_MAXLEN);
 }
 
-static int search_rsb_tree(struct rb_root *tree, char *name, int len,
-			   unsigned int flags, struct dlm_rsb **r_ret)
+int dlm_search_rsb_tree(struct rb_root *tree, char *name, int len,
+			unsigned int flags, struct dlm_rsb **r_ret)
 {
 	struct rb_node *node = tree->rb_node;
 	struct dlm_rsb *r;
@@ -474,12 +474,12 @@ static int _search_rsb(struct dlm_ls *ls, char *name, int len, int b,
 	struct dlm_rsb *r;
 	int error;
 
-	error = search_rsb_tree(&ls->ls_rsbtbl[b].keep, name, len, flags, &r);
+	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].keep, name, len, flags, &r);
 	if (!error) {
 		kref_get(&r->res_ref);
 		goto out;
 	}
-	error = search_rsb_tree(&ls->ls_rsbtbl[b].toss, name, len, flags, &r);
+	error = dlm_search_rsb_tree(&ls->ls_rsbtbl[b].toss, name, len, flags, &r);
 	if (error)
 		goto out;
 

fs/dlm/lock.h

@@ -28,6 +28,9 @@ void dlm_scan_waiters(struct dlm_ls *ls);
 void dlm_scan_timeout(struct dlm_ls *ls);
 void dlm_adjust_timeouts(struct dlm_ls *ls);
 
+int dlm_search_rsb_tree(struct rb_root *tree, char *name, int len,
+			unsigned int flags, struct dlm_rsb **r_ret);
+
 int dlm_purge_locks(struct dlm_ls *ls);
 void dlm_purge_mstcpy_locks(struct dlm_rsb *r);
 void dlm_grant_after_purge(struct dlm_ls *ls);