selftests: sixth test for mounting detached mounts onto detached mounts

Add a test to verify that detached mounts behave correctly.

Link: https://lore.kernel.org/r/20250221-brauner-open_tree-v1-15-dbcfcb98c676@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2025-02-21 14:13:14 +01:00
parent d346ae7a64
commit 0e6eef95df
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@ -2017,4 +2017,48 @@ TEST_F(mount_setattr, mount_detached1_onto_detached2_then_close_detached1_then_m
EXPECT_EQ(close(fd_tree2), 0);
}
TEST_F(mount_setattr, two_detached_mounts_referring_to_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 the same detached mount tree as @fd_tree1
*/
fd_tree2 = sys_open_tree(fd_tree1, "",
AT_NO_AUTOMOUNT | AT_SYMLINK_NOFOLLOW |
AT_EMPTY_PATH | OPEN_TREE_CLOEXEC);
ASSERT_GE(fd_tree2, 0);
/*
* Copy the following mount tree:
*
* |-/tmp/target1 testing tmpfs
* `-/tmp/target1/AA testing tmpfs
* `-/tmp/target1/AA/B testing tmpfs
* `-/tmp/target1/AA/B/BB testing tmpfs
*/
ASSERT_EQ(move_mount(fd_tree2, "", -EBADF, "/tmp/target1", MOVE_MOUNT_F_EMPTY_PATH), 0);
/*
* This must fail as this would mean adding the same mount tree
* into the same mount tree.
*/
ASSERT_NE(move_mount(fd_tree1, "", -EBADF, "/tmp/target1", MOVE_MOUNT_F_EMPTY_PATH), 0);
}
TEST_HARNESS_MAIN