diff --git a/fs/block_dev.c b/fs/block_dev.c
index 470c10ceb0fb3a33dc8f28e7e8b2d3535042075b..10d8a0aa871a096eb3d8577b01d285aa9c1fa433 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -931,8 +931,16 @@ static int do_open(struct block_device *bdev, struct file *file, int for_part)
 	struct gendisk *disk;
 	int ret;
 	int part;
+	int perm = 0;
 
-	ret = devcgroup_inode_permission(bdev->bd_inode, file->f_mode);
+	if (file->f_mode & FMODE_READ)
+		perm |= MAY_READ;
+	if (file->f_mode & FMODE_WRITE)
+		perm |= MAY_WRITE;
+	/*
+	 * hooks: /n/, see "layering violations".
+	 */
+	ret = devcgroup_inode_permission(bdev->bd_inode, perm);
 	if (ret != 0)
 		return ret;