[PATCH] dm: rwlock_t -> rw_semaphore (fluff)

Use a rw_semaphore in dm_target.c rather than a rwlock_t, just to keep
in line with dm.c

drivers/md/dm-target.c

@@ -19,7 +19,7 @@ struct tt_internal {
 };
 
 static LIST_HEAD(_targets);
-static rwlock_t _lock = RW_LOCK_UNLOCKED;
+static DECLARE_RWSEM(_lock);
 
 #define DM_MOD_NAME_SIZE 32
 
@@ -42,7 +42,7 @@ static struct tt_internal *get_target_type(const char *name)
 {
 	struct tt_internal *ti;
 
-	read_lock(&_lock);
+	down_read(&_lock);
 
 	ti = __find_target_type(name);
 	if (ti) {
@@ -52,7 +52,7 @@ static struct tt_internal *get_target_type(const char *name)
 			ti->use++;
 	}
 
-	read_unlock(&_lock);
+	up_read(&_lock);
 	return ti;
 }
 
@@ -86,13 +86,13 @@ void dm_put_target_type(struct target_type *t)
 {
 	struct tt_internal *ti = (struct tt_internal *) t;
 
-	read_lock(&_lock);
+	down_read(&_lock);
 	if (--ti->use == 0)
 		module_put(ti->tt.module);
 
 	if (ti->use < 0)
 		BUG();
-	read_unlock(&_lock);
+	up_read(&_lock);
 
 	return;
 }
@@ -117,13 +117,13 @@ int dm_register_target(struct target_type *t)
 	if (!ti)
 		return -ENOMEM;
 
-	write_lock(&_lock);
+	down_write(&_lock);
 	if (__find_target_type(t->name))
 		rv = -EEXIST;
 	else
 		list_add(&ti->list, &_targets);
 
-	write_unlock(&_lock);
+	up_write(&_lock);
 	return rv;
 }
 
@@ -131,21 +131,21 @@ int dm_unregister_target(struct target_type *t)
 {
 	struct tt_internal *ti;
 
-	write_lock(&_lock);
+	down_write(&_lock);
 	if (!(ti = __find_target_type(t->name))) {
-		write_unlock(&_lock);
+		up_write(&_lock);
 		return -EINVAL;
 	}
 
 	if (ti->use) {
-		write_unlock(&_lock);
+		up_write(&_lock);
 		return -ETXTBSY;
 	}
 
 	list_del(&ti->list);
 	kfree(ti);
 
-	write_unlock(&_lock);
+	up_write(&_lock);
 	return 0;
 }