dm: bind new table before destroying old

Commit Message

Alasdair G Kergon Nov. 11, 2009, 1:16 a.m. UTC

None

Patch

Index: linux-2.6.32-rc6/drivers/md/dm-table.c
===================================================================
--- linux-2.6.32-rc6.orig/drivers/md/dm-table.c
+++ linux-2.6.32-rc6/drivers/md/dm-table.c
@@ -237,6 +237,9 @@  void dm_table_destroy(struct dm_table *t
 {
 	unsigned int i;
 
+	if (!t)
+		return;
+
 	while (atomic_read(&t->holders))
 		msleep(1);
 	smp_mb();
Index: linux-2.6.32-rc6/drivers/md/dm.c
===================================================================
--- linux-2.6.32-rc6.orig/drivers/md/dm.c
+++ linux-2.6.32-rc6/drivers/md/dm.c
@@ -2070,7 +2070,10 @@  static int __bind(struct mapped_device *
 	return 0;
 }
 
-static void __unbind(struct mapped_device *md)
+/*
+ * Returns unbound table for the caller to free.
+ */
+struct dm_table *__unbind(struct mapped_device *md)
 {
 	struct dm_table *map = md->map;
 	unsigned long flags;
@@ -2082,7 +2085,8 @@  static void __unbind(struct mapped_devic
 	write_lock_irqsave(&md->map_lock, flags);
 	md->map = NULL;
 	write_unlock_irqrestore(&md->map_lock, flags);
-	dm_table_destroy(map);
+
+	return map;
 }
 
 /*
@@ -2175,7 +2179,7 @@  void dm_put(struct mapped_device *md)
 		}
 		dm_sysfs_exit(md);
 		dm_table_put(map);
-		__unbind(md);
+		dm_table_destroy(__unbind(md));
 		free_dev(md);
 	}
 }
@@ -2381,8 +2385,9 @@  int dm_swap_table(struct mapped_device *
 		goto out;
 	}
 
-	__unbind(md);
+	map = __unbind(md);
 	r = __bind(md, table, &limits);
+	dm_table_destroy(map);
 
 out:
 	mutex_unlock(&md->suspend_lock);