On Tue, 16 Nov 2021, Matthew Wilcox wrote: > On Tue, Nov 16, 2021 at 01:44:04PM +1100, NeilBrown wrote: > > swap-over-NFS currently has a variety of problems. > > > > Due to a newish test in generic_write_checks(), all writes to swap > > currently fail. > > And by "currently", you mean "for over two years" (August 2019). That's about the time scale for "enterprise" releases... Actually, the earliest patches that impacted swap-over-NFS was more like 4 years ago. I didn't bother tracking Fixes: tags for everything that was a fix, as I didn't think it would really help and might encourage people to backport little bits of the series which I wouldn't recommend. > Does swap-over-NFS (or any other network filesystem) actually have any > users, and should we fix it or rip it out? > > We have at least one user (why else would I be working on this?). I think we have more, though they are presumably still on an earlier release. I'd prefer "fix it" over "rip it out". I don't think any other network filesystem supports swap, but it is not trivial to grep for.. There must be a 'swap_activate' method, and it must return 0. There must also be a direct_IO that works. The only other network filesystem with swap_activate is cifs. It returns 0, but direct_IO returns -EINVAL. NeilBrown
