NFSD: Hoist status code encoding into XDR encoder functions

The original intent was presumably to reduce code duplication. The
trade-off was:

- No support for an NFSD proc function returning a non-success
  RPC accept_stat value.
- No support for void NFS replies to non-NULL procedures.
- Everyone pays for the deduplication with a few extra conditional
  branches in a hot path.

In addition, nfsd_dispatch() leaves *statp uninitialized in the
success path, unlike svc_generic_dispatch().

Address all of these problems by moving the logic for encoding
the NFS status code into the NFS XDR encoders themselves. Then
update the NFS .pc_func methods to return an RPC accept_stat
value.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 19 insertions, 4 deletions

diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
index 952e71c95d4e..8a288c8fcd57 100644
--- a/fs/nfsd/nfsxdr.c
+++ b/fs/nfsd/nfsxdr.c
@@ -430,14 +430,24 @@ nfssvc_encode_void(struct svc_rqst *rqstp, __be32 *p)
 }
 
 int
+nfssvc_encode_stat(struct svc_rqst *rqstp, __be32 *p)
+{
+	struct nfsd_stat *resp = rqstp->rq_resp;
+
+	*p++ = resp->status;
+	return xdr_ressize_check(rqstp, p);
+}
+
+int
 nfssvc_encode_attrstat(struct svc_rqst *rqstp, __be32 *p)
 {
 	struct nfsd_attrstat *resp = rqstp->rq_resp;
 
+	*p++ = resp->status;
 	if (resp->status != nfs_ok)
-		return xdr_ressize_check(rqstp, p);
-
+		goto out;
 	p = encode_fattr(rqstp, p, &resp->fh, &resp->stat);
+out:
 	return xdr_ressize_check(rqstp, p);
 }
 
@@ -446,11 +456,12 @@ nfssvc_encode_diropres(struct svc_rqst *rqstp, __be32 *p)
 {
 	struct nfsd_diropres *resp = rqstp->rq_resp;
 
+	*p++ = resp->status;
 	if (resp->status != nfs_ok)
-		return xdr_ressize_check(rqstp, p);
-
+		goto out;
 	p = encode_fh(p, &resp->fh);
 	p = encode_fattr(rqstp, p, &resp->fh, &resp->stat);
+out:
 	return xdr_ressize_check(rqstp, p);
 }
 
@@ -459,6 +470,7 @@ nfssvc_encode_readlinkres(struct svc_rqst *rqstp, __be32 *p)
 {
 	struct nfsd_readlinkres *resp = rqstp->rq_resp;
 
+	*p++ = resp->status;
 	if (resp->status != nfs_ok)
 		return xdr_ressize_check(rqstp, p);
 
@@ -479,6 +491,7 @@ nfssvc_encode_readres(struct svc_rqst *rqstp, __be32 *p)
 {
 	struct nfsd_readres *resp = rqstp->rq_resp;
 
+	*p++ = resp->status;
 	if (resp->status != nfs_ok)
 		return xdr_ressize_check(rqstp, p);
 
@@ -502,6 +515,7 @@ nfssvc_encode_readdirres(struct svc_rqst *rqstp, __be32 *p)
 {
 	struct nfsd_readdirres *resp = rqstp->rq_resp;
 
+	*p++ = resp->status;
 	if (resp->status != nfs_ok)
 		return xdr_ressize_check(rqstp, p);
 
@@ -520,6 +534,7 @@ nfssvc_encode_statfsres(struct svc_rqst *rqstp, __be32 *p)
 	struct nfsd_statfsres *resp = rqstp->rq_resp;
 	struct kstatfs	*stat = &resp->stats;
 
+	*p++ = resp->status;
 	if (resp->status != nfs_ok)
 		return xdr_ressize_check(rqstp, p);