mnt: Move the clear of MNT_LOCKED from copy_tree to it's callers.

mnt: Move the clear of MNT_LOCKED from copy_tree to it's callers.

commit 8486a7882b5ba906992fd78bbfcefaae7fe285cc upstream.

Clear MNT_LOCKED in the callers of copy_tree except copy_mnt_ns, and
collect_mounts.  In copy_mnt_ns it is necessary to create an exact
copy of a mount tree, so not clearing MNT_LOCKED is important.
Similarly collect_mounts is used to take a snapshot of the mount tree
for audit logging purposes and auditing using a faithful copy of the
tree is important.

This becomes particularly significant when we start setting MNT_LOCKED
on rootfs to prevent it from being unmounted.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>