Merge tag 'nfsd-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux

Pull nfsd updates from Chuck Lever:
 "Neil Brown contributed more scalability improvements to NFSD's open
  file cache, and Jeff Layton contributed a menagerie of repairs to
  NFSD's NFSv4 callback / backchannel implementation.

  Mike Snitzer contributed a change to NFS re-export support that
  disables support for file locking on a re-exported NFSv4 mount. This
  is because NFSv4 state recovery is currently difficult if not
  impossible for re-exported NFS mounts. The change aims to prevent data
  integrity exposures after the re-export server crashes.

  Work continues on the evolving NFSD netlink administrative API.

  Many thanks to the contributors, reviewers, testers, and bug reporters
  who participated during the v6.15 development cycle"

* tag 'nfsd-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux: (45 commits)
  NFSD: Add a Kconfig setting to enable delegated timestamps
  sysctl: Fixes nsm_local_state bounds
  nfsd: use a long for the count in nfsd4_state_shrinker_count()
  nfsd: remove obsolete comment from nfs4_alloc_stid
  nfsd: remove unneeded forward declaration of nfsd4_mark_cb_fault()
  nfsd: reorganize struct nfs4_delegation for better packing
  nfsd: handle errors from rpc_call_async()
  nfsd: move cb_need_restart flag into cb_flags
  nfsd: replace CB_GETATTR_BUSY with NFSD4_CALLBACK_RUNNING
  nfsd: eliminate cl_ra_cblist and NFSD4_CLIENT_CB_RECALL_ANY
  nfsd: prevent callback tasks running concurrently
  nfsd: disallow file locking and delegations for NFSv4 reexport
  nfsd: filecache: drop the list_lru lock during lock gc scans
  nfsd: filecache: don't repeatedly add/remove files on the lru list
  nfsd: filecache: introduce NFSD_FILE_RECENT
  nfsd: filecache: use list_lru_walk_node() in nfsd_file_gc()
  nfsd: filecache: use nfsd_file_dispose_list() in nfsd_file_close_inode_sync()
  NFSD: Re-organize nfsd_file_gc_worker()
  nfsd: filecache: remove race handling.
  fs: nfs: acl: Avoid -Wflex-array-member-not-at-end warning
  ...

2 files changed, 52 insertions, 3 deletions

diff --git a/Documentation/filesystems/nfs/reexport.rst b/Documentation/filesystems/nfs/reexport.rst
index ff9ae4a46530..044be965d75e 100644
--- a/Documentation/filesystems/nfs/reexport.rst
+++ b/Documentation/filesystems/nfs/reexport.rst
@@ -26,9 +26,13 @@ Reboot recovery
 ---------------
 
 The NFS protocol's normal reboot recovery mechanisms don't work for the
-case when the reexport server reboots.  Clients will lose any locks
-they held before the reboot, and further IO will result in errors.
-Closing and reopening files should clear the errors.
+case when the reexport server reboots because the source server has not
+rebooted, and so it is not in grace.  Since the source server is not in
+grace, it cannot offer any guarantees that the file won't have been
+changed between the locks getting lost and any attempt to recover them.
+The same applies to delegations and any associated locks.  Clients are
+not allowed to get file locks or delegations from a reexport server, any
+attempts will fail with operation not supported.
 
 Filehandle limits
 -----------------
diff --git a/Documentation/netlink/specs/lockd.yaml b/Documentation/netlink/specs/lockd.yaml
new file mode 100644
index 000000000000..bbd4da5fe54b
--- /dev/null
+++ b/Documentation/netlink/specs/lockd.yaml
@@ -0,0 +1,45 @@
+# SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
+
+name: lockd
+protocol: genetlink
+uapi-header: linux/lockd_netlink.h
+
+doc: lockd configuration over generic netlink
+
+attribute-sets:
+  -
+    name: server
+    attributes:
+      -
+        name: gracetime
+        type: u32
+      -
+        name: tcp-port
+        type: u16
+      -
+        name: udp-port
+        type: u16
+
+operations:
+  list:
+    -
+      name: server-set
+      doc: set the lockd server parameters
+      attribute-set: server
+      flags: [ admin-perm ]
+      do:
+        request:
+          attributes:
+            - gracetime
+            - tcp-port
+            - udp-port
+    -
+      name: server-get
+      doc: get the lockd server parameters
+      attribute-set: server
+      do:
+        reply:
+          attributes:
+            - gracetime
+            - tcp-port
+            - udp-port