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, 5 insertions, 0 deletions

diff --git a/fs/nfsd/xdr.h b/fs/nfsd/xdr.h
index 17221931815f..0ff336b0b25f 100644
--- a/fs/nfsd/xdr.h
+++ b/fs/nfsd/xdr.h
@@ -82,6 +82,10 @@ struct nfsd_readdirargs {
 	__be32 *		buffer;
 };
 
+struct nfsd_stat {
+	__be32			status;
+};
+
 struct nfsd_attrstat {
 	__be32			status;
 	struct svc_fh		fh;
@@ -153,6 +157,7 @@ int nfssvc_decode_linkargs(struct svc_rqst *, __be32 *);
 int nfssvc_decode_symlinkargs(struct svc_rqst *, __be32 *);
 int nfssvc_decode_readdirargs(struct svc_rqst *, __be32 *);
 int nfssvc_encode_void(struct svc_rqst *, __be32 *);
+int nfssvc_encode_stat(struct svc_rqst *, __be32 *);
 int nfssvc_encode_attrstat(struct svc_rqst *, __be32 *);
 int nfssvc_encode_diropres(struct svc_rqst *, __be32 *);
 int nfssvc_encode_readlinkres(struct svc_rqst *, __be32 *);