[PATCH] Fix handling of error code in NFSv4 replies

As nfsv4 does some reply encoding while processing
requests, the code which tries to put the overall status
at the head of the reply fails.

With this patch, we take the address for the overall
status very early so NFSv4's encoding wont confuse us.

fs/nfsd/nfs4proc.c

@@ -568,9 +568,9 @@ nfsd4_proc_compound(struct svc_rqst *rqstp,
 
 	resp->xbuf = &rqstp->rq_res;
 	resp->p = rqstp->rq_res.head[0].iov_base + rqstp->rq_res.head[0].iov_len;
-	resp->tagp = resp->p + 1; /* skip over status */
-	/* reserve space for: status, taglen, tag, and opcnt */
-	resp->p += 3 + XDR_QUADLEN(args->taglen);
+	resp->tagp = resp->p;
+	/* reserve space for: taglen, tag, and opcnt */
+	resp->p += 2 + XDR_QUADLEN(args->taglen);
 	resp->end = rqstp->rq_res.head[0].iov_base + PAGE_SIZE;
 	resp->taglen = args->taglen;
 	resp->tag = args->tag;

fs/nfsd/nfssvc.c

@@ -264,6 +264,7 @@ nfsd_dispatch(struct svc_rqst *rqstp, u32 *statp)
 	struct svc_procedure	*proc;
 	kxdrproc_t		xdr;
 	u32			nfserr;
+	u32			*nfserrp;
 
 	dprintk("nfsd_dispatch: vers %d proc %d\n",
 				rqstp->rq_vers, rqstp->rq_proc);
@@ -290,6 +291,13 @@ nfsd_dispatch(struct svc_rqst *rqstp, u32 *statp)
 		return 1;
 	}
 
+	/* need to grab the location to store the status, as
+	 * nfsv4 does some encoding while processing 
+	 */
+	nfserrp = rqstp->rq_res.head[0].iov_base
+		+ rqstp->rq_res.head[0].iov_len;
+	rqstp->rq_res.head[0].iov_len += sizeof(u32);
+
 	/* Now call the procedure handler, and encode NFS status. */
 	nfserr = proc->pc_func(rqstp, rqstp->rq_argp, rqstp->rq_resp);
 	if (nfserr == nfserr_dropit) {
@@ -299,14 +307,14 @@ nfsd_dispatch(struct svc_rqst *rqstp, u32 *statp)
 	}
 
 	if (rqstp->rq_proc != 0)
-		svc_putu32(&rqstp->rq_res.head[0], nfserr);
+		*nfserrp++ = nfserr;
 
 	/* Encode result.
 	 * For NFSv2, additional info is never returned in case of an error.
 	 */
 	if (!(nfserr && rqstp->rq_vers == 2)) {
 		xdr = proc->pc_encode;
-		if (xdr && !xdr(rqstp, (u32*)(rqstp->rq_res.head[0].iov_base+rqstp->rq_res.head[0].iov_len),
+		if (xdr && !xdr(rqstp, nfserrp,
 				rqstp->rq_resp)) {
 			/* Failed to encode result. Release cache entry */
 			dprintk("nfsd: failed to encode result!\n");