NFSD: Clean up nfsd4_encode_replay()

Replace open-coded encoding logic with the use of conventional XDR
utility functions. Add a tracepoint to make replays observable in
field troubleshooting situations.

The WARN_ON is removed. A stack trace is of little use, as there is
only one call site for nfsd4_encode_replay(), and a buffer length
shortage here is unlikely.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 9e8f230..fac938f 100644 (file)
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -5732,27 +5732,24 @@ release:
        rqstp->rq_next_page = xdr->page_ptr + 1;
 }
 
-/* 
- * Encode the reply stored in the stateowner reply cache 
- * 
- * XDR note: do not encode rp->rp_buflen: the buffer contains the
- * previously sent already encoded operation.
+/**
+ * nfsd4_encode_replay - encode a result stored in the stateowner reply cache
+ * @xdr: send buffer's XDR stream
+ * @op: operation being replayed
+ *
+ * @op->replay->rp_buf contains the previously-sent already-encoded result.
  */
-void
-nfsd4_encode_replay(struct xdr_stream *xdr, struct nfsd4_op *op)
+void nfsd4_encode_replay(struct xdr_stream *xdr, struct nfsd4_op *op)
 {
-       __be32 *p;
        struct nfs4_replay *rp = op->replay;
 
-       p = xdr_reserve_space(xdr, 8 + rp->rp_buflen);
-       if (!p) {
-               WARN_ON_ONCE(1);
-               return;
-       }
-       *p++ = cpu_to_be32(op->opnum);
-       *p++ = rp->rp_status;  /* already xdr'ed */
+       trace_nfsd_stateowner_replay(op->opnum, rp);
 
-       p = xdr_encode_opaque_fixed(p, rp->rp_buf, rp->rp_buflen);
+       if (xdr_stream_encode_u32(xdr, op->opnum) != XDR_UNIT)
+               return;
+       if (xdr_stream_encode_be32(xdr, rp->rp_status) != XDR_UNIT)
+               return;
+       xdr_stream_encode_opaque_fixed(xdr, rp->rp_buf, rp->rp_buflen);
 }
 
 void nfsd4_release_compoundargs(struct svc_rqst *rqstp)

diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
index d8e5626..e545e92 100644 (file)
--- a/fs/nfsd/trace.h
+++ b/fs/nfsd/trace.h
@@ -696,6 +696,24 @@ DEFINE_EVENT(nfsd_stid_class, nfsd_stid_##name,                    \
 
 DEFINE_STID_EVENT(revoke);
 
+TRACE_EVENT(nfsd_stateowner_replay,
+       TP_PROTO(
+               u32 opnum,
+               const struct nfs4_replay *rp
+       ),
+       TP_ARGS(opnum, rp),
+       TP_STRUCT__entry(
+               __field(unsigned long, status)
+               __field(u32, opnum)
+       ),
+       TP_fast_assign(
+               __entry->status = be32_to_cpu(rp->rp_status);
+               __entry->opnum = opnum;
+       ),
+       TP_printk("opnum=%u status=%lu",
+               __entry->opnum, __entry->status)
+);
+
 TRACE_EVENT_CONDITION(nfsd_seq4_status,
        TP_PROTO(
                const struct svc_rqst *rqstp,