dm: add dm_deleting_md function

Add dm_deleting_md to check whether or not a given mapped
device is currently being deleted.
Signed-off-by: Mike Anderson <andmike@linux.vnet.ibm.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

drivers/md/dm.c

@@ -329,6 +329,11 @@ static void __exit dm_exit(void)
 /*
  * Block device functions
  */
+int dm_deleting_md(struct mapped_device *md)
+{
+	return test_bit(DMF_DELETING, &md->flags);
+}
+
 static int dm_blk_open(struct block_device *bdev, fmode_t mode)
 {
 	struct mapped_device *md;
@@ -340,7 +345,7 @@ static int dm_blk_open(struct block_device *bdev, fmode_t mode)
 		goto out;
 
 	if (test_bit(DMF_FREEING, &md->flags) ||
-	    test_bit(DMF_DELETING, &md->flags)) {
+	    dm_deleting_md(md)) {
 		md = NULL;
 		goto out;
 	}
@@ -2659,7 +2664,7 @@ struct mapped_device *dm_get_from_kobject(struct kobject *kobj)
 		return NULL;
 
 	if (test_bit(DMF_FREEING, &md->flags) ||
-	    test_bit(DMF_DELETING, &md->flags))
+	    dm_deleting_md(md))
 		return NULL;
 
 	dm_get(md);

drivers/md/dm.h

@@ -88,6 +88,11 @@ int dm_target_iterate(void (*iter_func)(struct target_type *tt,
 
 int dm_split_args(int *argc, char ***argvp, char *input);
 
+/*
+ * Is this mapped_device being deleted?
+ */
+int dm_deleting_md(struct mapped_device *md);
+
 /*
  * The device-mapper can be driven through one of two interfaces;
  * ioctl or filesystem, depending which patch you have applied.