Add a test to verify that detached mounts behave correctly.
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
---
.../selftests/mount_setattr/mount_setattr_test.c | 36 ++++++++++++++++++++++
1 file changed, 36 insertions(+)
diff --git a/tools/testing/selftests/mount_setattr/mount_setattr_test.c b/tools/testing/selftests/mount_setattr/mount_setattr_test.c
index d2bf8b77df3f..1e0508cb5c2d 100644
--- a/tools/testing/selftests/mount_setattr/mount_setattr_test.c
+++ b/tools/testing/selftests/mount_setattr/mount_setattr_test.c
@@ -2061,4 +2061,40 @@ TEST_F(mount_setattr, two_detached_mounts_referring_to_same_anonymous_mount_name
ASSERT_NE(move_mount(fd_tree1, "", -EBADF, "/tmp/target1", MOVE_MOUNT_F_EMPTY_PATH), 0);
}
+TEST_F(mount_setattr, two_detached_subtrees_of_same_anonymous_mount_namespace)
+{
+ int fd_tree1 = -EBADF, fd_tree2 = -EBADF;
+
+ /*
+ * Copy the following mount tree:
+ *
+ * |-/mnt/A testing tmpfs
+ * `-/mnt/A/AA testing tmpfs
+ * `-/mnt/A/AA/B testing tmpfs
+ * `-/mnt/A/AA/B/BB testing tmpfs
+ */
+ fd_tree1 = sys_open_tree(-EBADF, "/mnt/A",
+ AT_NO_AUTOMOUNT | AT_SYMLINK_NOFOLLOW |
+ AT_RECURSIVE | OPEN_TREE_CLOEXEC |
+ OPEN_TREE_CLONE);
+ ASSERT_GE(fd_tree1, 0);
+
+ /*
+ * Create an O_PATH file descriptors with a separate struct file that
+ * refers to a subtree of the same detached mount tree as @fd_tree1
+ */
+ fd_tree2 = sys_open_tree(fd_tree1, "AA",
+ AT_NO_AUTOMOUNT | AT_SYMLINK_NOFOLLOW |
+ AT_EMPTY_PATH | OPEN_TREE_CLOEXEC);
+ ASSERT_GE(fd_tree2, 0);
+
+ /*
+ * This must fail as it is only possible to attach the root of a
+ * detached mount tree.
+ */
+ ASSERT_NE(move_mount(fd_tree2, "", -EBADF, "/tmp/target1", MOVE_MOUNT_F_EMPTY_PATH), 0);
+
+ ASSERT_EQ(move_mount(fd_tree1, "", -EBADF, "/tmp/target1", MOVE_MOUNT_F_EMPTY_PATH), 0);
+}
+
TEST_HARNESS_MAIN
--
2.47.2
