On Mon, Jan 19, 2026 at 06:22:42PM +1100, NeilBrown wrote: > On Mon, 19 Jan 2026, Christoph Hellwig wrote: > > On Mon, Jan 19, 2026 at 10:23:13AM +1100, NeilBrown wrote: > > > > This was Chuck's suggested name. His point was that STABLE means that > > > > the FH's don't change during the lifetime of the file. > > > > > > > > I don't much care about the flag name, so if everyone likes PERSISTENT > > > > better I'll roll with that. > > > > > > I don't like PERSISTENT. > > > I'd rather call a spade a spade. > > > > > > EXPORT_OP_SUPPORTS_NFS_EXPORT > > > or > > > EXPORT_OP_NOT_NFS_COMPATIBLE > > > > > > The issue here is NFS export and indirection doesn't bring any benefits. > > > > No, it absolutely is not. And the whole concept of calling something > > after the initial or main use is a recipe for a mess. > > We are calling it for it's only use. If there was ever another use, we > could change the name if that made sense. It is not a public name, it > is easy to change. > > > > > Pick a name that conveys what the flag is about, and document those > > semantics well. This flag is about the fact that for a given file, > > as long as that file exists in the file system the handle is stable. > > Both stable and persistent are suitable for that, nfs is everything > > but. > > My understanding is that kernfs would not get the flag. > kernfs filehandles do not change as long as the file exist. > But this is not sufficient for the files to be usefully exported. > > I suspect kernfs does re-use filehandles relatively soon after the > file/object has been destroyed. Maybe that is the real problem here: > filehandle reuse, not filehandle stability. > > Jeff: could you please give details (and preserve them in future cover > letters) of which filesystems are known to have problems and what > exactly those problems are? > > > > > Remember nfs also support volatile file handles, and other applications > > might rely on this (I know of quite a few user space applications that > > do, but they are kinda hardwired to xfs anyway). > > The NFS protocol supports volatile file handles. knfsd does not. > So maybe > EXPORT_OP_NOT_NFSD_COMPATIBLE > might be better. or EXPORT_OP_NOT_LINUX_NFSD_COMPATIBLE. > (I prefer opt-out rather than opt-in because nfsd export was the > original purpose of export_operations, but it isn't something > I would fight for)
I prefer one of the variants you proposed here but I don't particularly care. It's not a hill worth dying on. So if Christoph insists on the other name then I say let's just go with it.
