This is great, thanks: On Mon, Nov 30, 2020 at 04:24:50PM -0500, trondmy@xxxxxxxxxx wrote: > From: Jeff Layton <jeff.layton@xxxxxxxxxxxxxxx> > > With NFSv3 nfsd will always attempt to send along WCC data to the > client. This generally involves saving off the in-core inode information > prior to doing the operation on the given filehandle, and then issuing a > vfs_getattr to it after the op. > > Some filesystems (particularly clustered or networked ones) have an > expensive ->getattr inode operation. Atomicitiy is also often difficult > or impossible to guarantee on such filesystems. For those, we're best > off not trying to provide WCC information to the client at all, and to > simply allow it to poll for that information as needed with a GETATTR > RPC. > > This patch adds a new flags field to struct export_operations, and > defines a new EXPORT_OP_NOWCC flag that filesystems can use to indicate > that nfsd should not attempt to provide WCC info in NFSv3 replies. It > also adds a blurb about the new flags field and flag to the exporting > documentation. In the v4 case I think it should also turn off the "atomic" flag in the change_info4 structure that's returned by some operations. (Out of curiosity: have you seen this cause actual bugs?) --b.
