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Date:   Tue, 10 May 2022 22:24:28 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     "Darrick J. Wong" <djwong@kernel.org>
Cc:     Dan Williams <dan.j.williams@intel.com>,
        Dave Chinner <david@fromorbit.com>,
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Subject: Re: [PATCHSETS] v14 fsdax-rmap + v11 fsdax-reflink
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On Tue, 10 May 2022 19:43:01 -0700 "Darrick J. Wong" <djwong@kernel.org> wrote:

> On Tue, May 10, 2022 at 07:28:53PM -0700, Andrew Morton wrote:
> > On Tue, 10 May 2022 18:55:50 -0700 Dan Williams <dan.j.williams@intel.com> wrote:
> > 
> > > > It'll need to be a stable branch somewhere, but I don't think it
> > > > really matters where al long as it's merged into the xfs for-next
> > > > tree so it gets filesystem test coverage...
> > > 
> > > So how about let the notify_failure() bits go through -mm this cycle,
> > > if Andrew will have it, and then the reflnk work has a clean v5.19-rc1
> > > baseline to build from?
> > 
> > What are we referring to here?  I think a minimal thing would be the
> > memremap.h and memory-failure.c changes from
> > https://lkml.kernel.org/r/20220508143620.1775214-4-ruansy.fnst@fujitsu.com ?
> > 
> > Sure, I can scoot that into 5.19-rc1 if you think that's best.  It
> > would probably be straining things to slip it into 5.19.
> > 
> > The use of EOPNOTSUPP is a bit suspect, btw.  It *sounds* like the
> > right thing, but it's a networking errno.  I suppose livable with if it
> > never escapes the kernel, but if it can get back to userspace then a
> > user would be justified in wondering how the heck a filesystem
> > operation generated a networking errno?
> 
> <shrug> most filesystems return EOPNOTSUPP rather enthusiastically when
> they don't know how to do something...

Can it propagate back to userspace?