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Subject: Re: [PATCH v7 2/4] NFSD: allow client to use write delegation
 stateid for READ
From:   Jeff Layton <jlayton@kernel.org>
To:     dai.ngo@oracle.com, chuck.lever@oracle.com
Cc:     linux-nfs@vger.kernel.org
Date:   Fri, 11 Aug 2023 15:06:22 -0400
In-Reply-To: <83cd1107-2efe-f16c-2015-3da15aec12a5@oracle.com>
References: <1688089960-24568-1-git-send-email-dai.ngo@oracle.com>
         <1688089960-24568-3-git-send-email-dai.ngo@oracle.com>
         <6756f84c4ff92845298ce4d7e3c4f0fb20671d3d.camel@kernel.org>
         <83cd1107-2efe-f16c-2015-3da15aec12a5@oracle.com>
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Yep. Reverting that patch seemed to fix the problem. Chuck, mind just
dropping this patch from nfsd-next?

Thanks,
Jeff


On Fri, 2023-08-11 at 10:47 -0700, dai.ngo@oracle.com wrote:
> Hi Jeff,
>=20
> I have not looked at this carefully, but since now we only grant
> write delegation for OPEN with both read and write access then
> perhaps this patch is no longer needed?
>=20
> -Dai
>=20
> On 8/11/23 10:22 AM, Jeff Layton wrote:
> > On Thu, 2023-06-29 at 18:52 -0700, Dai Ngo wrote:
> > > Allow NFSv4 client to use write delegation stateid for READ operation=
.
> > > Per RFC 8881 section 9.1.2. Use of the Stateid and Locking.
> > >=20
> > > Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> > > ---
> > >   fs/nfsd/nfs4proc.c | 16 ++++++++++++++--
> > >   fs/nfsd/nfs4xdr.c  |  9 +++++++++
> > >   fs/nfsd/xdr4.h     |  2 ++
> > >   3 files changed, 25 insertions(+), 2 deletions(-)
> > >=20
> > > diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> > > index 5ae670807449..3fa66cb38780 100644
> > > --- a/fs/nfsd/nfs4proc.c
> > > +++ b/fs/nfsd/nfs4proc.c
> > > @@ -942,8 +942,18 @@ nfsd4_read(struct svc_rqst *rqstp, struct nfsd4_=
compound_state *cstate,
> > >   	/* check stateid */
> > >   	status =3D nfs4_preprocess_stateid_op(rqstp, cstate, &cstate->curr=
ent_fh,
> > >   					&read->rd_stateid, RD_STATE,
> > > -					&read->rd_nf, NULL);
> > > -
> > > +					&read->rd_nf, &read->rd_wd_stid);
> > I think this patch is causing breakage with pynfs. WRT3 sends a READ
> > operation with the zero-stateid. On earlier kernels, this works, but a
> > linux-next kernel=A0rejects this with BAD_STATEID.
> >=20
> > nfs4_preprocess_stateid_op seems to assume that if cstid is set, then
> > it's a copy operation and anonymous stateids aren't allowed. Maybe that
> > test should be something besides checking cstid =3D=3D NULL?
> >=20
> > > +	/*
> > > +	 * rd_wd_stid is needed for nfsd4_encode_read to allow write
> > > +	 * delegation stateid used for read. Its refcount is decremented
> > > +	 * by nfsd4_read_release when read is done.
> > > +	 */
> > > +	if (!status && (read->rd_wd_stid->sc_type !=3D NFS4_DELEG_STID ||
> > > +			delegstateid(read->rd_wd_stid)->dl_type !=3D
> > > +			NFS4_OPEN_DELEGATE_WRITE)) {
> > > +		nfs4_put_stid(read->rd_wd_stid);
> > > +		read->rd_wd_stid =3D NULL;
> > > +	}
> > >   	read->rd_rqstp =3D rqstp;
> > >   	read->rd_fhp =3D &cstate->current_fh;
> > >   	return status;
> > > @@ -953,6 +963,8 @@ nfsd4_read(struct svc_rqst *rqstp, struct nfsd4_c=
ompound_state *cstate,
> > >   static void
> > >   nfsd4_read_release(union nfsd4_op_u *u)
> > >   {
> > > +	if (u->read.rd_wd_stid)
> > > +		nfs4_put_stid(u->read.rd_wd_stid);
> > >   	if (u->read.rd_nf)
> > >   		nfsd_file_put(u->read.rd_nf);
> > >   	trace_nfsd_read_done(u->read.rd_rqstp, u->read.rd_fhp,
> > > diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> > > index 76db2fe29624..e0640b31d041 100644
> > > --- a/fs/nfsd/nfs4xdr.c
> > > +++ b/fs/nfsd/nfs4xdr.c
> > > @@ -4120,6 +4120,7 @@ nfsd4_encode_read(struct nfsd4_compoundres *res=
p, __be32 nfserr,
> > >   	struct file *file;
> > >   	int starting_len =3D xdr->buf->len;
> > >   	__be32 *p;
> > > +	fmode_t o_fmode =3D 0;
> > >  =20
> > >   	if (nfserr)
> > >   		return nfserr;
> > > @@ -4139,10 +4140,18 @@ nfsd4_encode_read(struct nfsd4_compoundres *r=
esp, __be32 nfserr,
> > >   	maxcount =3D min_t(unsigned long, read->rd_length,
> > >   			 (xdr->buf->buflen - xdr->buf->len));
> > >  =20
> > > +	if (read->rd_wd_stid) {
> > > +		/* allow READ using write delegation stateid */
> > > +		o_fmode =3D file->f_mode;
> > > +		file->f_mode |=3D FMODE_READ;
> > > +	}
> > >   	if (file->f_op->splice_read && splice_ok)
> > >   		nfserr =3D nfsd4_encode_splice_read(resp, read, file, maxcount);
> > >   	else
> > >   		nfserr =3D nfsd4_encode_readv(resp, read, file, maxcount);
> > > +	if (o_fmode)
> > > +		file->f_mode =3D o_fmode;
> > > +
> > >   	if (nfserr) {
> > >   		xdr_truncate_encode(xdr, starting_len);
> > >   		return nfserr;
> > > diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h
> > > index 510978e602da..3ccc40f9274a 100644
> > > --- a/fs/nfsd/xdr4.h
> > > +++ b/fs/nfsd/xdr4.h
> > > @@ -307,6 +307,8 @@ struct nfsd4_read {
> > >   	struct svc_rqst		*rd_rqstp;          /* response */
> > >   	struct svc_fh		*rd_fhp;            /* response */
> > >   	u32			rd_eof;             /* response */
> > > +
> > > +	struct nfs4_stid	*rd_wd_stid;		/* internal */
> > >   };
> > >  =20
> > >   struct nfsd4_readdir {

--=20
Jeff Layton <jlayton@kernel.org>