nfsd: don't use the deferral service, return NFS4ERR_DELAY

On an NFSv4.1 server cache miss that causes an upcall, NFS4ERR_DELAY will be
returned. It is up to the NFSv4.1 client to resend only the operations that
have not been processed.

Initialize rq_usedeferral to 1 in svc_process(). It sill be turned off in
nfsd4_proc_compound() only when NFSv4.1 Sessions are used.

Note: this isn't an adequate solution on its own. It's acceptable as a way
to get some minimal 4.1 up and working, but we're going to have to find a
way to avoid returning DELAY in all common cases before 4.1 can really be
considered ready.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[nfsd41: reverse rq_nodeferral negative logic]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[sunrpc: initialize rq_usedeferral]
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

4 files changed, 12 insertions, 1 deletions

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 249dad987a16..ded469ff08b3 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -854,6 +854,8 @@ nfsd4_proc_compound(struct svc_rqst *rqstp,
         resp->cstate.replay_owner = NULL;
         fh_init(&resp->cstate.current_fh, NFS4_FHSIZE);
         fh_init(&resp->cstate.save_fh, NFS4_FHSIZE);
+        /* Use the deferral mechanism only for NFSv4.0 compounds */
+        rqstp->rq_usedeferral = (args->minorversion == 0);
 
         /*
          * According to RFC3010, this takes precedence over all other errors.
@@ -933,12 +935,18 @@ encode_op:
 
                 nfsd4_increment_op_stats(op->opnum);
         }
+        if (!rqstp->rq_usedeferral && status == nfserr_dropit) {
+                dprintk("%s Dropit - send NFS4ERR_DELAY\n", __func__);
+                status = nfserr_jukebox;
+        }
 
         fh_put(&resp->cstate.current_fh);
         fh_put(&resp->cstate.save_fh);
         BUG_ON(resp->cstate.replay_owner);
 out:
         nfsd4_release_compoundargs(args);
+        /* Reset deferral mechanism for RPC deferrals */
+        rqstp->rq_usedeferral = 1;
         dprintk("nfsv4 compound returned %d\n", ntohl(status));
         return status;
 }
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 9f9f699dd469..815dd589d4db 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -230,6 +230,7 @@ struct svc_rqst {
         struct svc_cred         rq_cred;        /* auth info */
         void *                  rq_xprt_ctxt;   /* transport specific context ptr */
         struct svc_deferred_req*rq_deferred;    /* deferred request we are replaying */
+        int                     rq_usedeferral; /* use deferral */
 
         size_t                  rq_xprt_hlen;   /* xprt header len */
         struct xdr_buf          rq_arg;
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index fff09a2d8960..45984cbe1bfa 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -1023,6 +1023,8 @@ svc_process(struct svc_rqst *rqstp)
         rqstp->rq_res.tail[0].iov_len = 0;
         /* Will be turned off only in gss privacy case: */
         rqstp->rq_splice_ok = 1;
+        /* Will be turned off only when NFSv4 Sessions are used */
+        rqstp->rq_usedeferral = 1;
 
         /* Setup reply header */
         rqstp->rq_xprt->xpt_ops->xpo_prep_reply_hdr(rqstp);
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 1e66f2491460..600d0918e3ae 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -974,7 +974,7 @@ static struct cache_deferred_req *svc_defer(struct cache_req *req)
         struct svc_rqst *rqstp = container_of(req, struct svc_rqst, rq_chandle);
         struct svc_deferred_req *dr;
 
-        if (rqstp->rq_arg.page_len)
+        if (rqstp->rq_arg.page_len || !rqstp->rq_usedeferral)
                 return NULL; /* if more than a page, give up FIXME */
         if (rqstp->rq_deferred) {
                 dr = rqstp->rq_deferred;