[PATCH] device-mapper: Trigger an event when a table is deleted

If anything is waiting on a device's table when the device is removed, we
must first wake it up so it will release its reference.  Otherwise the
table's reference count will not drop to zero and the table will not get
removed.
Signed-Off-By: NAlasdair G Kergon <agk@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

drivers/md/dm-ioctl.c

@@ -230,11 +230,20 @@ static int dm_hash_insert(const char *name, const char *uuid, struct mapped_devi
 
 static void __hash_remove(struct hash_cell *hc)
 {
+	struct dm_table *table;
+
 	/* remove from the dev hash */
 	list_del(&hc->uuid_list);
 	list_del(&hc->name_list);
 	unregister_with_devfs(hc);
 	dm_set_mdptr(hc->md, NULL);
+
+	table = dm_get_table(hc->md);
+	if (table) {
+		dm_table_event(table);
+		dm_table_put(table);
+	}
+
 	dm_put(hc->md);
 	if (hc->new_map)
 		dm_table_put(hc->new_map);