Re: [PATCH 04/11] vfs: add missing checks to copy_file_range

Olga Kornievskaia
2018-12-12T20:22:36Z

On Wed, Dec 12, 2018 at 2:43 PM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Wed, Dec 12, 2018 at 01:55:28PM -0500, Olga Kornievskaia wrote:
> > On Wed, Dec 12, 2018 at 6:31 AM Luis Henriques <lhenriques@suse.com> wrote:
> > > I was wondering if, with the above check, it would make sense to also
> > > have an extra patch changing some filesystems (ceph, nfs and cifs) to
> > > simply return -EOPNOTSUPP (instead of -EINVAL) when inode_in ==
> > > inode_out. Something like the diff below (not tested!).
>
> > > +++ b/fs/nfs/nfs4file.c
> > > @@ -136,7 +136,7 @@ static ssize_t nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
> > > ssize_t ret;
> > >
> > > if (file_inode(file_in) == file_inode(file_out))
> > > - return -EINVAL;
> > > + return -EOPNOTSUPP;
> >
> > Please don't change the NFS bits. This is against the NFS
> > specifications. RFC 7862 15.2.3
> >
> > (snippet)
> > SAVED_FH and CURRENT_FH must be different files. If SAVED_FH and
> > CURRENT_FH refer to the same file, the operation MUST fail with
> > NFS4ERR_INVAL.
>
> I don't see how that applies. That refers to a requirement _in the
> protocol_ that determines what the server MUST do if the client sends
> it two FHs which refer to the same file.
>
> What we're talking about here is how a Linux filesystem behaves when
> receiving a copy_file_range() referring to the same file. As long as
> the Linux filesystem doesn't react by sending out one of these invalid
> protocol messages, I don't see the problem.

Ok then this should be changed to call generic_copy_file_range() not
returning the EOPNOTSUPP since there is no longer fallback in vfs to
call the generic_copy_file_range() and in turn responsibility of each
file system.