Re: [PATCH v2] selftests/mount_setattr: fix idmap_mount_tree_invalid failed to run

[Christian Brauner]

On Mon, Oct 28, 2024 at 04:41:32PM +0800, zhouyuhang wrote:
> From: zhouyuhang <zhouyuhang@xxxxxxxxxx>
> 
> Test case idmap_mount_tree_invalid failed to run on the newer kernel
> with the following output:
> 
>  #  RUN           mount_setattr_idmapped.idmap_mount_tree_invalid ...
>  # mount_setattr_test.c:1428:idmap_mount_tree_invalid:Expected sys_mount_setattr(open_tree_fd, "", AT_EMPTY_PATH, &attr,  sizeof(attr)) (0) ! = 0 (0)
>  # idmap_mount_tree_invalid: Test terminated by assertion
> 
> This is because tmpfs is mounted at "/mnt/A", and tmpfs already
> contains the flag FS_ALLOW_IDMAP after the commit 7a80e5b8c6fa ("shmem:
> support idmapped mounts for tmpfs"). So calling sys_mount_setattr here
> returns 0 instead of -EINVAL as expected.
> 
> Ramfs does not support idmap mounts, so we can use it here to test invalid mounts,
> which allows the test case to pass with the following output:
> 
>  # Starting 1 tests from 1 test cases.
>  #  RUN           mount_setattr_idmapped.idmap_mount_tree_invalid ...
>  #            OK  mount_setattr_idmapped.idmap_mount_tree_invalid
>  ok 1 mount_setattr_idmapped.idmap_mount_tree_invalid
>  # PASSED: 1 / 1 tests passed.
> 
> Signed-off-by: zhouyuhang <zhouyuhang@xxxxxxxxxx>
> ---

Reviewed-by: Christian Brauner <brauner@xxxxxxxxxx>