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selftests: seventh test for mounting detached mounts onto detached mounts

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Add a test to verify that detached mounts behave correctly.

Link: https://lore.kernel.org/r/20250221-brauner-open_tree-v1-16-dbcfcb98c676@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner
2025-02-21 14:13:15 +01:00
parent 0e6eef95df
commit 7bece690a9
1 changed files with 36 additions and 0 deletions
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36
tools/testing/selftests/mount_setattr/mount_setattr_test.c
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@@ -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