dm array: fix bug in growing array

Entries would be lost if the old tail block was partially filled.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # 3.9+

drivers/md/persistent-data/dm-array.c

@@ -509,15 +509,18 @@ static int grow_add_tail_block(struct resize *resize)
 static int grow_needs_more_blocks(struct resize *resize)
 {
 	int r;
+	unsigned old_nr_blocks = resize->old_nr_full_blocks;
 
 	if (resize->old_nr_entries_in_last_block > 0) {
+		old_nr_blocks++;
+
 		r = grow_extend_tail_block(resize, resize->max_entries);
 		if (r)
 			return r;
 	}
 
 	r = insert_full_ablocks(resize->info, resize->size_of_block,
-				resize->old_nr_full_blocks,
+				old_nr_blocks,
 				resize->new_nr_full_blocks,
 				resize->max_entries, resize->value,
 				&resize->root);