mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-17 07:14:59 -04:00
32f54f2bbc
Add a test suite for the UNSHARE_EMPTY_MNTNS and CLONE_EMPTY_MNTNS flags exercising the empty mount namespace functionality through the kselftest harness. The tests cover: - basic functionality: unshare succeeds, exactly one mount exists in the new namespace, root and cwd point to the same mount - flag interactions: UNSHARE_EMPTY_MNTNS works standalone without explicit CLONE_NEWNS, combines correctly with CLONE_NEWUSER and other namespace flags (CLONE_NEWUTS, CLONE_NEWIPC) - edge cases: EPERM without capabilities, works from a user namespace, many source mounts still result in one mount, cwd on a different mount gets reset to root - error paths: invalid flags return EINVAL - regression: plain CLONE_NEWNS still copies the full mount tree, other namespace unshares are unaffected - mount properties: the root mount has the expected statmount properties, is its own parent, and is the only entry returned by listmount - repeated unshare: consecutive UNSHARE_EMPTY_MNTNS calls each produce a new namespace with a distinct mount ID - overmount workflow: verifies the intended usage pattern of creating an empty mount namespace with a nullfs root and then mounting tmpfs over it to build a writable filesystem from scratch Link: https://patch.msgid.link/20260306-work-empty-mntns-consolidated-v1-2-6eb30529bbb0@kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>