On Wed, Jun 28, 2023 at 07:36:15PM -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.
I'm wondering if this fix should precede 2/5 to prevent breakage
during a bisect. Jeff, what do you think?
> Signed-off-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
> ---
> fs/nfsd/nfs4proc.c | 16 ++++++++++++++--
> fs/nfsd/nfs4xdr.c | 9 +++++++++
> fs/nfsd/xdr4.h | 2 ++
> 3 files changed, 25 insertions(+), 2 deletions(-)
>
> 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 = nfs4_preprocess_stateid_op(rqstp, cstate, &cstate->current_fh,
> &read->rd_stateid, RD_STATE,
> - &read->rd_nf, NULL);
> -
> + &read->rd_nf, &read->rd_wd_stid);
> + /*
> + * 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 != NFS4_DELEG_STID ||
> + delegstateid(read->rd_wd_stid)->dl_type !=
> + NFS4_OPEN_DELEGATE_WRITE)) {
> + nfs4_put_stid(read->rd_wd_stid);
> + read->rd_wd_stid = NULL;
> + }
> read->rd_rqstp = rqstp;
> read->rd_fhp = &cstate->current_fh;
> return status;
> @@ -953,6 +963,8 @@ nfsd4_read(struct svc_rqst *rqstp, struct nfsd4_compound_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 b35855c8beb6..833634cdc761 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -4125,6 +4125,7 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, __be32 nfserr,
> struct file *file;
> int starting_len = xdr->buf->len;
> __be32 *p;
> + fmode_t o_fmode = 0;
>
> if (nfserr)
> return nfserr;
> @@ -4144,10 +4145,18 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, __be32 nfserr,
> maxcount = min_t(unsigned long, read->rd_length,
> (xdr->buf->buflen - xdr->buf->len));
>
> + if (read->rd_wd_stid) {
> + /* allow READ using write delegation stateid */
> + o_fmode = file->f_mode;
> + file->f_mode |= FMODE_READ;
> + }
> if (file->f_op->splice_read && splice_ok)
> nfserr = nfsd4_encode_splice_read(resp, read, file, maxcount);
> else
> nfserr = nfsd4_encode_readv(resp, read, file, maxcount);
> + if (o_fmode)
> + file->f_mode = 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 */
> };
>
> struct nfsd4_readdir {
> --
> 2.39.3
>
