nfsd: add data structures for handling CB_NOTIFY

Add the data structures, allocation helpers, and callback operations
needed for directory delegation CB_NOTIFY support:

- struct nfsd_notify_event: carries fsnotify events for CB_NOTIFY
- struct nfsd4_cb_notify: per-delegation state for notification handling
- Union dl_cb_fattr with dl_cb_notify in nfs4_delegation since a
  delegation is either a regular file delegation or a directory
  delegation, never both

Refactor alloc_init_deleg() into a common __alloc_init_deleg() base
with a pluggable sc_free callback, and add alloc_init_dir_deleg() which
allocates the page array and notify4 buffer needed for CB_NOTIFY
encoding.

Add skeleton nfsd4_cb_notify_ops with done/release handlers that will
be filled in when the notification path is wired up.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260616-dir-deleg-v7-9-6cbc7eac0ade@kernel.org
Signed-off-by: Chuck Lever <cel@kernel.org>

0 files changed, 0 insertions, 0 deletions