[PATCH v4 0/2] NFSD: memory shrinker for NFSv4 clients

[Dai Ngo <dai.ngo@oracle.com>]

This patch series implements the memory shrinker for NFSv4 clients
to react to system low memory condition.

The memory shrinker's count callback is used to trigger the laundromat.
The actual work of destroying the expired clients is done by the
laundromat itself. We can not destroying the expired clients on the
memory shrinler's scan callback context to avoid possible deadlock.

By destroying the expired clients, all states associated with these
clients are also released.

v2:
. fix kernel test robot errors in nfsd.h when CONFIG_NFSD_V4 not defined.

v3:
. add mod_delayed_work in nfsd_courtesy_client_scan to kick start
  the laundromat.

v4:
. replace the use of xchg() with vanilla '=' in patch 1.

---

Dai Ngo (2):
      NFSD: keep track of the number of courtesy clients in the system
      NFSD: add shrinker to reap courtesy clients on low memory condition

 fs/nfsd/netns.h     |  5 ++++
 fs/nfsd/nfs4state.c | 65 ++++++++++++++++++++++++++++++++++++++++++++----
 fs/nfsd/nfsctl.c    |  6 +++--
 fs/nfsd/nfsd.h      |  9 +++++--
 4 files changed, 76 insertions(+), 9 deletions(-)