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From:   Olga Kornievskaia <olga.kornievskaia@gmail.com>
Date:   Thu, 11 Apr 2019 12:53:39 -0400
Message-ID: <CAN-5tyGrqQLpwdLPsFofUeSCDHY0Spt80YBu0au5m16mi4yPAA@mail.gmail.com>
Subject: Re: [PATCH 1/1] NFSv4.1 fix incorrect return value in copy_file_range
To:     Trond Myklebust <trondmy@hammerspace.com>
Cc:     "anna.schumaker@netapp.com" <anna.schumaker@netapp.com>,
        "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>
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Sender: linux-nfs-owner@vger.kernel.org
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On Thu, Apr 11, 2019 at 12:52 PM Olga Kornievskaia
<olga.kornievskaia@gmail.com> wrote:
>
> On Thu, Apr 11, 2019 at 12:46 PM Trond Myklebust
> <trondmy@hammerspace.com> wrote:
> >
> > On Thu, 2019-04-11 at 12:27 -0400, Olga Kornievskaia wrote:
> > > From: Olga Kornievskaia <kolga@netapp.com>
> > >
> > > When VFS calls copy_file_range on a 4.0 mount (and when in and out
> > > file is the same), we need to return ENOTSUPP instead of EINVAL.
> > > Since no COPY operation is defined in 4.0, then like 3.0, it should
> > > fallback to doing do_splice_direct().
> > >
> > > Otherwise xfstest generic/075,091,112,263 fail.
> > >
> > > Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
> > > ---
> > >  fs/nfs/nfs4file.c | 6 ++++++
> > >  1 file changed, 6 insertions(+)
> > >
> > > diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
> > > index 45b2322..9a222b0 100644
> > > --- a/fs/nfs/nfs4file.c
> > > +++ b/fs/nfs/nfs4file.c
> > > @@ -133,6 +133,12 @@ static ssize_t nfs4_copy_file_range(struct file
> > > *file_in, loff_t pos_in,
> > >                                   struct file *file_out, loff_t
> > > pos_out,
> > >                                   size_t count, unsigned int flags)
> > >  {
> > > +     struct nfs_server *server = NFS_SERVER(file_inode(file_in);
> > > +     struct nfs_client *client = server->nfs_client;
> > > +
> > > +     if (client->cl_minorversion < 1)
> > > +             return -EOPNOTSUPP;
> > > +
> > >       if (file_inode(file_in) == file_inode(file_out))
> > >               return -EINVAL;
> > >       return nfs42_proc_copy(file_in, pos_in, file_out, pos_out,
> > > count);
> >
> > Let's please just move the test for NFS_CAP_COPY from nfs42_proc_copy()
> > into the above function.
>
> But the return order of errors here for different conditions matter.
> For 4.1+ mounts, if in == out, we'd expect EINVAL even if server isn't
> capable. But we can't just put the in == out first because for 4.0, we
> need to always return EOPNOTSUPP.

Urgh, I just realized a problem in my own check. It needs to be < 2 as
there is no COPY in 4.1.

> > BTW: Why do we return -EINVAL in the file_in == file_out case? Is there
> > any reason why we shouldn't just return EOPNOTSUPP there too in order
> > to let splice() fulfil the operation?
>
> Yes: in == out -> EINVAL is a spec requirement.
>
> >
> > --
> > Trond Myklebust
> > Linux NFS client maintainer, Hammerspace
> > trond.myklebust@hammerspace.com
> >
> >