Re: [PATCH v2 01/31] Documentation: document EXPORT_OP_NOLOCKS
Jeff Layton <[email protected]>
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On Tue, 2026-01-20 at 08:20 -0500, Jeff Layton wrote: > On Mon, 2026-01-19 at 23:44 -0800, Christoph Hellwig wrote: > > On Mon, Jan 19, 2026 at 11:26:18AM -0500, Jeff Layton wrote: > > > + 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. -- Jeff Layton <[email protected]>