On Tue, Jul 13, 2021 at 01:13:22PM +0200, Christian Brauner wrote:

From: Christian Brauner <redacted>

Various filesystems use the lookup_one_len_unlocked() helper to lookup a single
path component relative to a well-known starting point. Allow such filesystems
to support idmapped mounts by enabling lookup_one_len_unlocked() to take the
idmap into account when calling inode_permission().

Ditto.  The same applies to the rest of primitives you modify - if you need
a new variant, *add* *that* *variant*.