[PATCH v2 0/8] nfsd: reduce the scope of the nfsd_mutex

[Jeff Layton <jlayton@kernel.org>]

This version fixes a couple of minor issues that Sashiko flagged, and
also implements a suggestion by Neil to use guard() with the new
filecache mutex.

Original cover letter follows:

-------------------8<--------------------

Currently much of nfsd's administration is serialized under the global
nfsd_mutex, even though most of the objects managed under it are
segregated by net namespace.

This patchset does a couple of small cleanups and then adds a new
per-net mutex and moves all of the appropriate per-net data structures
to be protected by it instead of the global mutex. The filecache is
given its own mutex, and the global mutex is renamed and left for
managing just the few remaning global objects.

I also had an LLM cook up some selftests so we can hopefully keep all of
this working properly in the future.

Please consider for v7.4.

Thanks,
Jeff

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
Changes in v2:
- Fix potential deadlock in cross-namespace isolation selftest
- Drop binaries from selftest patches
- Use guard() in nfsd_file_cache_init()
- Link to v1: https://lore.kernel.org/r/20260921-nfsd-per-net-mutex-v1-0-4a7287f6504c@kernel.org

---
Jeff Layton (8):
      nfsd: clear NFSD_NET_UP before dropping the generic resource reference
      nfsd: make max_blksize a per-namespace setting
      nfsd: move the control plane to a per-namespace mutex
      nfsd: rename nfsd_mutex to nfsd_global_mutex
      nfsd: give the open file cache its own mutex
      selftests/nfsd: factor the netlink plumbing into a shared header
      selftests/nfsd: add cross-namespace isolation tests
      selftests/nfsd: add a cross-namespace control-plane soak

 fs/nfsd/export.c                                   |  22 +-
 fs/nfsd/filecache.c                                |  26 +-
 fs/nfsd/netns.h                                    |  16 +
 fs/nfsd/nfs4proc.c                                 |   4 +-
 fs/nfsd/nfs4state.c                                |   8 +-
 fs/nfsd/nfsctl.c                                   | 129 ++---
 fs/nfsd/nfsd.h                                     |   4 +-
 fs/nfsd/nfssvc.c                                   | 146 ++++--
 tools/testing/selftests/nfsd/.gitignore            |   2 +
 tools/testing/selftests/nfsd/Makefile              |   2 +
 tools/testing/selftests/nfsd/config                |   6 +
 tools/testing/selftests/nfsd/nfsd_netlink.h        | 319 ++++++++++++
 .../testing/selftests/nfsd/nfsd_netlink_listener.c | 301 +----------
 .../testing/selftests/nfsd/nfsd_netns_isolation.c  | 468 +++++++++++++++++
 tools/testing/selftests/nfsd/nfsd_netns_stress.c   | 572 +++++++++++++++++++++
 tools/testing/selftests/nfsd/settings              |   2 +-
 16 files changed, 1592 insertions(+), 435 deletions(-)
---
base-commit: aeaddc6a3711283c09a9183068897d4fe1fb464f
change-id: 20260918-nfsd-per-net-mutex-8655764940ac

Best regards,
-- 
Jeff Layton <jlayton@kernel.org>