dlm: change rsbtbl rwlock to spinlock

The rwlock is almost always used in write mode, so there's no reason
to not use a spinlock instead.
Signed-off-by: David Teigland <teigland@redhat.com>

fs/dlm/debug_fs.c

@@ -416,7 +416,7 @@ static void *table_seq_start(struct seq_file *seq, loff_t *pos)
 	if (seq->op == &format3_seq_ops)
 		ri->format = 3;
 
-	read_lock(&ls->ls_rsbtbl[bucket].lock);
+	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) {
@@ -424,12 +424,12 @@ static void *table_seq_start(struct seq_file *seq, loff_t *pos)
 				dlm_hold_rsb(r);
 				ri->rsb = r;
 				ri->bucket = bucket;
-				read_unlock(&ls->ls_rsbtbl[bucket].lock);
+				spin_unlock(&ls->ls_rsbtbl[bucket].lock);
 				return ri;
 			}
 		}
 	}
-	read_unlock(&ls->ls_rsbtbl[bucket].lock);
+	spin_unlock(&ls->ls_rsbtbl[bucket].lock);
 
 	/*
 	 * move to the first rsb in the next non-empty bucket
@@ -447,18 +447,18 @@ static void *table_seq_start(struct seq_file *seq, loff_t *pos)
 			return NULL;
 		}
 
-		read_lock(&ls->ls_rsbtbl[bucket].lock);
+		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);
 			dlm_hold_rsb(r);
 			ri->rsb = r;
 			ri->bucket = bucket;
-			read_unlock(&ls->ls_rsbtbl[bucket].lock);
+			spin_unlock(&ls->ls_rsbtbl[bucket].lock);
 			*pos = n;
 			return ri;
 		}
-		read_unlock(&ls->ls_rsbtbl[bucket].lock);
+		spin_unlock(&ls->ls_rsbtbl[bucket].lock);
 	}
 }
 
@@ -477,7 +477,7 @@ static void *table_seq_next(struct seq_file *seq, void *iter_ptr, loff_t *pos)
 	 * move to the next rsb in the same bucket
 	 */
 
-	read_lock(&ls->ls_rsbtbl[bucket].lock);
+	spin_lock(&ls->ls_rsbtbl[bucket].lock);
 	rp = ri->rsb;
 	next = rp->res_hashchain.next;
 
@@ -485,12 +485,12 @@ static void *table_seq_next(struct seq_file *seq, void *iter_ptr, loff_t *pos)
 		r = list_entry(next, struct dlm_rsb, res_hashchain);
 		dlm_hold_rsb(r);
 		ri->rsb = r;
-		read_unlock(&ls->ls_rsbtbl[bucket].lock);
+		spin_unlock(&ls->ls_rsbtbl[bucket].lock);
 		dlm_put_rsb(rp);
 		++*pos;
 		return ri;
 	}
-	read_unlock(&ls->ls_rsbtbl[bucket].lock);
+	spin_unlock(&ls->ls_rsbtbl[bucket].lock);
 	dlm_put_rsb(rp);
 
 	/*
@@ -509,18 +509,18 @@ static void *table_seq_next(struct seq_file *seq, void *iter_ptr, loff_t *pos)
 			return NULL;
 		}
 
-		read_lock(&ls->ls_rsbtbl[bucket].lock);
+		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);
 			dlm_hold_rsb(r);
 			ri->rsb = r;
 			ri->bucket = bucket;
-			read_unlock(&ls->ls_rsbtbl[bucket].lock);
+			spin_unlock(&ls->ls_rsbtbl[bucket].lock);
 			*pos = n;
 			return ri;
 		}
-		read_unlock(&ls->ls_rsbtbl[bucket].lock);
+		spin_unlock(&ls->ls_rsbtbl[bucket].lock);
 	}
 }
 

fs/dlm/dlm_internal.h

@@ -105,7 +105,7 @@ struct dlm_dirtable {
 struct dlm_rsbtable {
 	struct list_head	list;
 	struct list_head	toss;
-	rwlock_t		lock;
+	spinlock_t		lock;
 };
 
 struct dlm_lkbtable {

fs/dlm/lock.c

@@ -412,9 +412,9 @@ static int search_rsb(struct dlm_ls *ls, char *name, int len, int b,
 		      unsigned int flags, struct dlm_rsb **r_ret)
 {
 	int error;
-	write_lock(&ls->ls_rsbtbl[b].lock);
+	spin_lock(&ls->ls_rsbtbl[b].lock);
 	error = _search_rsb(ls, name, len, b, flags, r_ret);
-	write_unlock(&ls->ls_rsbtbl[b].lock);
+	spin_unlock(&ls->ls_rsbtbl[b].lock);
 	return error;
 }
 
@@ -478,16 +478,16 @@ static int find_rsb(struct dlm_ls *ls, char *name, int namelen,
 		r->res_nodeid = nodeid;
 	}
 
-	write_lock(&ls->ls_rsbtbl[bucket].lock);
+	spin_lock(&ls->ls_rsbtbl[bucket].lock);
 	error = _search_rsb(ls, name, namelen, bucket, 0, &tmp);
 	if (!error) {
-		write_unlock(&ls->ls_rsbtbl[bucket].lock);
+		spin_unlock(&ls->ls_rsbtbl[bucket].lock);
 		dlm_free_rsb(r);
 		r = tmp;
 		goto out;
 	}
 	list_add(&r->res_hashchain, &ls->ls_rsbtbl[bucket].list);
-	write_unlock(&ls->ls_rsbtbl[bucket].lock);
+	spin_unlock(&ls->ls_rsbtbl[bucket].lock);
 	error = 0;
  out:
 	*r_ret = r;
@@ -530,9 +530,9 @@ static void put_rsb(struct dlm_rsb *r)
 	struct dlm_ls *ls = r->res_ls;
 	uint32_t bucket = r->res_bucket;
 
-	write_lock(&ls->ls_rsbtbl[bucket].lock);
+	spin_lock(&ls->ls_rsbtbl[bucket].lock);
 	kref_put(&r->res_ref, toss_rsb);
-	write_unlock(&ls->ls_rsbtbl[bucket].lock);
+	spin_unlock(&ls->ls_rsbtbl[bucket].lock);
 }
 
 void dlm_put_rsb(struct dlm_rsb *r)
@@ -967,7 +967,7 @@ static int shrink_bucket(struct dlm_ls *ls, int b)
 
 	for (;;) {
 		found = 0;
-		write_lock(&ls->ls_rsbtbl[b].lock);
+		spin_lock(&ls->ls_rsbtbl[b].lock);
 		list_for_each_entry_reverse(r, &ls->ls_rsbtbl[b].toss,
 					    res_hashchain) {
 			if (!time_after_eq(jiffies, r->res_toss_time +
@@ -978,20 +978,20 @@ static int shrink_bucket(struct dlm_ls *ls, int b)
 		}
 
 		if (!found) {
-			write_unlock(&ls->ls_rsbtbl[b].lock);
+			spin_unlock(&ls->ls_rsbtbl[b].lock);
 			break;
 		}
 
 		if (kref_put(&r->res_ref, kill_rsb)) {
 			list_del(&r->res_hashchain);
-			write_unlock(&ls->ls_rsbtbl[b].lock);
+			spin_unlock(&ls->ls_rsbtbl[b].lock);
 
 			if (is_master(r))
 				dir_remove(r);
 			dlm_free_rsb(r);
 			count++;
 		} else {
-			write_unlock(&ls->ls_rsbtbl[b].lock);
+			spin_unlock(&ls->ls_rsbtbl[b].lock);
 			log_error(ls, "tossed rsb in use %s", r->res_name);
 		}
 	}
@@ -4224,7 +4224,7 @@ static struct dlm_rsb *find_purged_rsb(struct dlm_ls *ls, int bucket)
 {
 	struct dlm_rsb *r, *r_ret = NULL;
 
-	read_lock(&ls->ls_rsbtbl[bucket].lock);
+	spin_lock(&ls->ls_rsbtbl[bucket].lock);
 	list_for_each_entry(r, &ls->ls_rsbtbl[bucket].list, res_hashchain) {
 		if (!rsb_flag(r, RSB_LOCKS_PURGED))
 			continue;
@@ -4233,7 +4233,7 @@ static struct dlm_rsb *find_purged_rsb(struct dlm_ls *ls, int bucket)
 		r_ret = r;
 		break;
 	}
-	read_unlock(&ls->ls_rsbtbl[bucket].lock);
+	spin_unlock(&ls->ls_rsbtbl[bucket].lock);
 	return r_ret;
 }
 

fs/dlm/lockspace.c

@@ -464,7 +464,7 @@ static int new_lockspace(char *name, int namelen, void **lockspace,
 	for (i = 0; i < size; i++) {
 		INIT_LIST_HEAD(&ls->ls_rsbtbl[i].list);
 		INIT_LIST_HEAD(&ls->ls_rsbtbl[i].toss);
-		rwlock_init(&ls->ls_rsbtbl[i].lock);
+		spin_lock_init(&ls->ls_rsbtbl[i].lock);
 	}
 
 	size = dlm_config.ci_lkbtbl_size;

fs/dlm/recover.c

@@ -726,7 +726,7 @@ int dlm_create_root_list(struct dlm_ls *ls)
 	}
 
 	for (i = 0; i < ls->ls_rsbtbl_size; i++) {
-		read_lock(&ls->ls_rsbtbl[i].lock);
+		spin_lock(&ls->ls_rsbtbl[i].lock);
 		list_for_each_entry(r, &ls->ls_rsbtbl[i].list, res_hashchain) {
 			list_add(&r->res_root_list, &ls->ls_root_list);
 			dlm_hold_rsb(r);
@@ -737,7 +737,7 @@ int dlm_create_root_list(struct dlm_ls *ls)
 		   but no other recovery steps should do anything with them. */
 
 		if (dlm_no_directory(ls)) {
-			read_unlock(&ls->ls_rsbtbl[i].lock);
+			spin_unlock(&ls->ls_rsbtbl[i].lock);
 			continue;
 		}
 
@@ -745,7 +745,7 @@ int dlm_create_root_list(struct dlm_ls *ls)
 			list_add(&r->res_root_list, &ls->ls_root_list);
 			dlm_hold_rsb(r);
 		}
-		read_unlock(&ls->ls_rsbtbl[i].lock);
+		spin_unlock(&ls->ls_rsbtbl[i].lock);
 	}
  out:
 	up_write(&ls->ls_root_sem);
@@ -775,7 +775,7 @@ void dlm_clear_toss_list(struct dlm_ls *ls)
 	int i;
 
 	for (i = 0; i < ls->ls_rsbtbl_size; i++) {
-		write_lock(&ls->ls_rsbtbl[i].lock);
+		spin_lock(&ls->ls_rsbtbl[i].lock);
 		list_for_each_entry_safe(r, safe, &ls->ls_rsbtbl[i].toss,
 					 res_hashchain) {
 			if (dlm_no_directory(ls) || !is_master(r)) {
@@ -783,7 +783,7 @@ void dlm_clear_toss_list(struct dlm_ls *ls)
 				dlm_free_rsb(r);
 			}
 		}
-		write_unlock(&ls->ls_rsbtbl[i].lock);
+		spin_unlock(&ls->ls_rsbtbl[i].lock);
 	}
 }