On Tue, 2026-01-20 at 09:12 -0500, Jeff Layton wrote:

On Tue, 2026-01-20 at 08:20 -0500, Jeff Layton wrote:

quoted

On Mon, 2026-01-19 at 23:44 -0800, Christoph Hellwig wrote:

quoted

On Mon, Jan 19, 2026 at 11:26:18AM -0500, Jeff Layton wrote:

quoted

+  EXPORT_OP_NOLOCKS - Disable file locking on this filesystem. Some
+    filesystems cannot properly support file locking as implemented by
+    nfsd. A case in point is reexport of NFS itself, which can't be done
+    safely without coordinating the grace period handling. Other clustered
+    and networked filesystems can be problematic here as well.

I'm not sure this is very useful.  It really needs to document what
locking semantics nfs expects, because otherwise no reader will know
if they set this or not.

Fair point. I'll see if I can draft something better. Suggestions
welcome.

How about this?

+  EXPORT_OP_NOLOCKS - Disable file locking on this filesystem. Filesystems
+    that want to support locking over NFS must support POSIX file locking
+    semantics and must handle lock recovery requests from clients after a
+    reboot. Most local disk, RAM, or pseudo-filesystems use the generic POSIX
+    locking support in the kernel and naturally provide this capability. Network
+    or clustered filesystems usually need special handling to do this properly.

Even better, I think?

+
+  EXPORT_OP_NOLOCKS - Disable file locking on this filesystem. Filesystems
+    that want to support locking over NFS must support POSIX file locking
+    semantics. When the server reboots, the clients will issue requests to
+    recover their locks, which nfsd will issue to the filesystem as new lock
+    requests. Those must succeed in order for lock recovery to work. Most
+    local disk, RAM, or pseudo-filesystems use the generic POSIX locking
+    support in the kernel and naturally provide this capability. Network or
+    clustered filesystems usually need special handling to do this properly.
+    Set this flag on filesystems that can't guarantee the proper semantics
+    (e.g. reexported NFS).

-- 
Jeff Layton [off-list ref]


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