nfsd: Initial implementation of NFSv4 Courteous Server [LWN.net]

From:		Dai Ngo <dai.ngo-AT-oracle.com>
To:		bfields-AT-fieldses.org
Subject:		[PATCH RFC v3 0/2] nfsd: Initial implementation of NFSv4 Courteous Server
Date:		Thu, 16 Sep 2021 14:22:09 -0400
Message-ID:		<20210916182212.81608-1-dai.ngo@oracle.com>
Cc:		chuck.lever-AT-oracle.com, linux-nfs-AT-vger.kernel.org, linux-fsdevel-AT-vger.kernel.org
Archive-link:		Article

Hi Bruce,

This series of patches implement the NFSv4 Courteous Server.

A server which does not immediately expunge the state on lease expiration
is known as a Courteous Server.  A Courteous Server continues to recognize
previously generated state tokens as valid until conflict arises between
the expired state and the requests from another client, or the server
reboots.

The v2 patch includes the following:

. add new callback, lm_expire_lock, to lock_manager_operations to
  allow the lock manager to take appropriate action with conflict lock.

. handle conflicts of NFSv4 locks with NFSv3/NLM and local locks.

. expire courtesy client after 24hr if client has not reconnected.

. do not allow expired client to become courtesy client if there are
  waiters for client's locks.

. modify client_info_show to show courtesy client and seconds from
  last renew.

. fix a problem with NFSv4.1 server where the it keeps returning
  SEQ4_STATUS_CB_PATH_DOWN in the successful SEQUENCE reply, after
  the courtesy client re-connects, causing the client to keep sending
  BCTS requests to server.

The v3 patch includes the following:

. modify posix_test_lock to check and resolve conflict locks
  for handling of NLM TEST and NFSv4 LOCKT requests.

. separate out fix for back channel stuck in SEQ4_STATUS_CB_PATH_DOWN.

. merge with 5.15-rc1