dm: verify suspend_locking assumptions at runtime

Ensure that the assumptions about the caller holding suspend_lock
are checked at runtime if lockdep is enabled.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-table.c

@@ -1680,6 +1680,8 @@ static void suspend_targets(struct dm_table *t, enum suspend_mode mode)
 	int i = t->num_targets;
 	struct dm_target *ti = t->targets;
 
+	lockdep_assert_held(&t->md->suspend_lock);
+
 	while (i--) {
 		switch (mode) {
 		case PRESUSPEND:
@@ -1727,6 +1729,8 @@ int dm_table_resume_targets(struct dm_table *t)
 {
 	int i, r = 0;
 
+	lockdep_assert_held(&t->md->suspend_lock);
+
 	for (i = 0; i < t->num_targets; i++) {
 		struct dm_target *ti = t->targets + i;
 

drivers/md/dm.c

@@ -1698,6 +1698,8 @@ static void event_callback(void *context)
  */
 static void __set_size(struct mapped_device *md, sector_t size)
 {
+	lockdep_assert_held(&md->suspend_lock);
+
 	set_capacity(md->disk, size);
 
 	i_size_write(md->bdev->bd_inode, (loff_t)size << SECTOR_SHIFT);
@@ -2147,8 +2149,6 @@ static void unlock_fs(struct mapped_device *md)
  * If __dm_suspend returns 0, the device is completely quiescent
  * now. There is no request-processing activity. All new requests
  * are being added to md->deferred list.
- *
- * Caller must hold md->suspend_lock
  */
 static int __dm_suspend(struct mapped_device *md, struct dm_table *map,
 			unsigned suspend_flags, long task_state,
@@ -2364,6 +2364,8 @@ static void __dm_internal_suspend(struct mapped_device *md, unsigned suspend_fla
 {
 	struct dm_table *map = NULL;
 
+	lockdep_assert_held(&md->suspend_lock);
+
 	if (md->internal_suspend_count++)
 		return; /* nested internal suspend */