Re: [PATCH 0/3] NFS: Disable READ_PLUS by default

From: Olga Kornievskaia <aglo@umich.edu>
To: Trond Myklebust <trondmy@hammerspace.com>
Cc: "tigran.mkrtchyan@desy.de" <tigran.mkrtchyan@desy.de>,
	"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
	"Anna.Schumaker@netapp.com" <Anna.Schumaker@netapp.com>,
	"schumaker.anna@gmail.com" <schumaker.anna@gmail.com>
Subject: Re: [PATCH 0/3] NFS: Disable READ_PLUS by default
Date: Wed, 9 Dec 2020 12:40:09 -0500	[thread overview]
Message-ID: <CAN-5tyFgtD5iR4NciDg=DHg5aAwAZju89KzEYsUi9X6NwBQacQ@mail.gmail.com> (raw)
In-Reply-To: <b61c9e480cd2cc516d64d1f3e0376a748dbb3be9.camel@hammerspace.com>

On Wed, Dec 9, 2020 at 12:32 PM Trond Myklebust <trondmy@hammerspace.com> wrote:
>
> On Wed, 2020-12-09 at 12:22 -0500, Olga Kornievskaia wrote:
> > On Wed, Dec 9, 2020 at 12:12 PM Trond Myklebust <
> > trondmy@hammerspace.com> wrote:
> > >
> > > On Wed, 2020-12-09 at 12:07 -0500, Olga Kornievskaia wrote:
> > > > On Wed, Dec 9, 2020 at 11:59 AM Trond Myklebust
> > > > <trondmy@hammerspace.com> wrote:
> > > > >
> > > > > On Fri, 2020-12-04 at 15:00 -0500, Olga Kornievskaia wrote:
> > > > > > I object to putting the disable patch in, I think we need to
> > > > > > fix
> > > > > > the
> > > > > > problem.
> > > > >
> > > > > I can't see the problem is fixable in 5.10. There are way too
> > > > > many
> > > > > changes required, and we're in the middle of the week of the
> > > > > last -
> > > > > rc
> > > > > for 5.10. Furthermore, there are no regressions introduced by
> > > > > just
> > > > > disabling the functionality, because READ_PLUS has only just
> > > > > been
> > > > > merged in this release cycle.
> > > > >
> > > > > I therefore strongly suggest we just send [PATCH 1/3] NFS:
> > > > > Disable
> > > > > READ_PLUS by default and then fix the rest in 5.11.
> > > >
> > > > Sure, but shouldn't there be more ifdefs inside of the xdr code
> > > > to
> > > > turn it off completely?
> > >
> > > AFAICT, those functions are not called by anything else, so as long
> > > as
> > > the READ_PLUS client functionality is disabled, they should be
> > > harmless.
> >
> > Is it benign that in the normal read path sunrpc will be calling a
> > new
> > function of xdr_realign_pages()? Non readplus code didn't have it.
> > >
>
> Looking at commit 06216ecbd9368 (
> https://git.linux-nfs.org/?p=trondmy/linux-nfs.git;a=commitdiff;h=06216ecbd9368
> ) it is not actually changing the Linux-5.9 code, but is just
> performing a trivial refactoring of that code into a new function. I'm
> OK with that.
>
> The rest of the READ code looks unchanged to me.

Thank you for checking.

> --
> Trond Myklebust
> Linux NFS client maintainer, Hammerspace
> trond.myklebust@hammerspace.com
>
>