ext2: adjust block num when retry allocation

Set block num to original *count in a case
of retrying allocation in case num < *count

Link: https://lore.kernel.org/r/20191020232326.84881-1-cgxu519@mykernel.net
Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/ext2/balloc.c

@@ -1404,6 +1404,7 @@ allocated:
 		 * use.  So we may want to selectively mark some of the blocks
 		 * as free
 		 */
+		num = *count;
 		goto retry_alloc;
 	}