On Thu, 2019-04-11 at 13:16 -0400, Olga Kornievskaia wrote:
> On Thu, Apr 11, 2019 at 1:06 PM Trond Myklebust <
> trondmy@xxxxxxxxxxxxxxx> wrote:
> > On Thu, 2019-04-11 at 12:52 -0400, Olga Kornievskaia wrote:
> > > On Thu, Apr 11, 2019 at 12:46 PM Trond Myklebust
> > > <trondmy@xxxxxxxxxxxxxxx> wrote:
> > > > On Thu, 2019-04-11 at 12:27 -0400, Olga Kornievskaia wrote:
> > > > > From: Olga Kornievskaia <kolga@xxxxxxxxxx>
> > > > >
> > > > > 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@xxxxxxxxxx>
> > > > > ---
> > > > > 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.
> > >
> > > > 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.
> > >
> >
> > Returning NFS4ERR_INVAL when the files are identical is a
> > requirement
> > for the NFSv4.2 server.
> >
> > On the other hand, the requirement for the Linux file copy
> > operation is
> > that it should succeed in this situation. So as far as I can tell,
> > we
> > will continue to fail xfstests until we work around the discrepancy
> > with the protocol requirement here. The simplest way to do so would
> > appear to be to return EOPNOTSUPP.
>
> Ok so you are arguing that those xfstest's for copy_file_range() on
> the same file shouldn't fail for any of the NFS version regardless of
> the NFSv4.2 req for not doing a copy on the same file. Let me send
> out
> another version that addresses both then. I will change the "in ==
> out" to return EOPNOTSUPP which will allow the fallback for 4.2+ and
> check for the server capability before that.
Right. The point on the client should be to fulfil the requirements of
the copy_file_range() spec, so that applications can code to that spec
without needing to know any details of how the NFS client tries to
implement it. When there is a functionality gap with the NFS spec for
COPY (such as is the case here) then we should fall back to emulation
of the copy_file_range() spec.
...and again, I'd like to avoid any tests of cl_minorversion in the NFS
code. We can and should always replace that with tests for server
functionality, which is what the NFS_CAP_* flags are for. This is
particularly true now that we're expected to code to the more flexible
minor versioning scheme as described in RFC8178.
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@xxxxxxxxxxxxxxx
