[PATCH v8 16/18] nfsd: implement server support for NFS_LOCALIO_PROGRAM

[Mike Snitzer <snitzer@kernel.org>]

LOCALIOPROC_GETUUID encodes the server's uuid_t in terms of the fixed
UUID_SIZE (16). The fixed size opaque encode and decode XDR methods
are used instead of the less efficient variable sized methods.

Aside from a bit of code in nfssvc.c, all the knowledge of the LOCALIO
RPC protocol is in fs/nfsd/localio.c which implements just a single
version (1) that is used independently of what NFS version is used.

Signed-off-by: Mike Snitzer <snitzer@kernel.org>
[neilb: factored out and simplified single localio protocol]
Co-developed-by: NeilBrown <neil@brown.name>
Signed-off-by: NeilBrown <neil@brown.name>
---
 fs/nfsd/localio.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++
 fs/nfsd/nfssvc.c  | 29 ++++++++++++++++++-
 2 files changed, 102 insertions(+), 1 deletion(-)

diff --git a/fs/nfsd/localio.c b/fs/nfsd/localio.c
index 819589ae2008..e5d4c665ff07 100644
--- a/fs/nfsd/localio.c
+++ b/fs/nfsd/localio.c
@@ -11,12 +11,15 @@
 #include <linux/sunrpc/svcauth_gss.h>
 #include <linux/sunrpc/clnt.h>
 #include <linux/nfs.h>
+#include <linux/nfs_fs.h>
+#include <linux/nfs_xdr.h>
 #include <linux/string.h>
 
 #include "nfsd.h"
 #include "vfs.h"
 #include "netns.h"
 #include "filecache.h"
+#include "cache.h"
 
 #define NFSDDBG_FACILITY		NFSDDBG_FH
 
@@ -253,3 +256,74 @@ EXPORT_SYMBOL_GPL(nfsd_open_local_fh);
 
 /* Compile time type checking, not used by anything */
 static nfs_to_nfsd_open_t __maybe_unused nfsd_open_local_fh_typecheck = nfsd_open_local_fh;
+
+/*
+ * GETUUID XDR encode functions
+ */
+
+static __be32 localio_proc_null(struct svc_rqst *rqstp)
+{
+	return rpc_success;
+}
+
+struct localio_getuuidres {
+	uuid_t			uuid;
+};
+
+static __be32 localio_proc_getuuid(struct svc_rqst *rqstp)
+{
+	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
+	struct localio_getuuidres *resp = rqstp->rq_resp;
+
+	uuid_copy(&resp->uuid, &nn->nfsd_uuid.uuid);
+
+	return rpc_success;
+}
+
+static bool localio_encode_getuuidres(struct svc_rqst *rqstp,
+				      struct xdr_stream *xdr)
+{
+	struct localio_getuuidres *resp = rqstp->rq_resp;
+	u8 uuid[UUID_SIZE];
+
+	export_uuid(uuid, &resp->uuid);
+	encode_opaque_fixed(xdr, uuid, UUID_SIZE);
+
+	return true;
+}
+
+static const struct svc_procedure localio_procedures1[] = {
+	[LOCALIOPROC_NULL] = {
+		.pc_func = localio_proc_null,
+		.pc_decode = nfssvc_decode_voidarg,
+		.pc_encode = nfssvc_encode_voidres,
+		.pc_argsize = sizeof(struct nfsd_voidargs),
+		.pc_ressize = sizeof(struct nfsd_voidres),
+		.pc_cachetype = RC_NOCACHE,
+		.pc_xdrressize = 0,
+		.pc_name = "NULL",
+	},
+	[LOCALIOPROC_GETUUID] = {
+		.pc_func = localio_proc_getuuid,
+		.pc_decode = nfssvc_decode_voidarg,
+		.pc_encode = localio_encode_getuuidres,
+		.pc_argsize = sizeof(struct nfsd_voidargs),
+		.pc_ressize = sizeof(struct localio_getuuidres),
+		.pc_cachetype = RC_NOCACHE,
+		.pc_xdrressize = XDR_QUADLEN(UUID_SIZE),
+		.pc_name = "GETUUID",
+	},
+};
+
+#define LOCALIO_NR_PROCEDURES ARRAY_SIZE(localio_procedures1)
+static DEFINE_PER_CPU_ALIGNED(unsigned long,
+			      localio_count[LOCALIO_NR_PROCEDURES]);
+const struct svc_version localio_version1 = {
+	.vs_vers	= 1,
+	.vs_nproc	= LOCALIO_NR_PROCEDURES,
+	.vs_proc	= localio_procedures1,
+	.vs_dispatch	= nfsd_dispatch,
+	.vs_count	= localio_count,
+	.vs_xdrsize	= XDR_QUADLEN(UUID_SIZE),
+	.vs_hidden	= true,
+};
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index be5acb7a4057..abcbb05fca31 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -81,6 +81,26 @@ DEFINE_SPINLOCK(nfsd_drc_lock);
 unsigned long	nfsd_drc_max_mem;
 unsigned long	nfsd_drc_mem_used;
 
+#if IS_ENABLED(CONFIG_NFSD_LOCALIO)
+extern const struct svc_version localio_version1;
+static const struct svc_version *localio_versions[] = {
+	[1] = &localio_version1,
+};
+
+#define NFSD_LOCALIO_NRVERS		ARRAY_SIZE(localio_versions)
+
+static struct svc_program	nfsd_localio_program = {
+	.pg_prog		= NFS_LOCALIO_PROGRAM,
+	.pg_nvers		= NFSD_LOCALIO_NRVERS,
+	.pg_vers		= localio_versions,
+	.pg_name		= "nfslocalio",
+	.pg_class		= "nfsd",
+	.pg_authenticate	= &svc_set_client,
+	.pg_init_request	= svc_generic_init_request,
+	.pg_rpcbind_set		= svc_generic_rpcbind_set,
+};
+#endif /* CONFIG_NFSD_LOCALIO */
+
 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
 static const struct svc_version *nfsd_acl_version[] = {
 # if defined(CONFIG_NFSD_V2_ACL)
@@ -95,6 +115,9 @@ static const struct svc_version *nfsd_acl_version[] = {
 #define NFSD_ACL_NRVERS		ARRAY_SIZE(nfsd_acl_version)
 
 static struct svc_program	nfsd_acl_program = {
+#if IS_ENABLED(CONFIG_NFSD_LOCALIO)
+	.pg_next		= &nfsd_localio_program,
+#endif /* CONFIG_NFSD_LOCALIO */
 	.pg_prog		= NFS_ACL_PROGRAM,
 	.pg_nvers		= NFSD_ACL_NRVERS,
 	.pg_vers		= nfsd_acl_version,
@@ -123,6 +146,10 @@ static const struct svc_version *nfsd_version[] = {
 struct svc_program		nfsd_program = {
 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
 	.pg_next		= &nfsd_acl_program,
+#else
+#if IS_ENABLED(CONFIG_NFSD_LOCALIO)
+	.pg_next		= &nfsd_localio_program,
+#endif /* CONFIG_NFSD_LOCALIO */
 #endif
 	.pg_prog		= NFS_PROGRAM,		/* program number */
 	.pg_nvers		= NFSD_NRVERS,		/* nr of entries in nfsd_version */
@@ -1014,7 +1041,7 @@ nfsd(void *vrqstp)
 }
 
 /**
- * nfsd_dispatch - Process an NFS or NFSACL Request
+ * nfsd_dispatch - Process an NFS or NFSACL or LOCALIO Request
  * @rqstp: incoming request
  *
  * This RPC dispatcher integrates the NFS server's duplicate reply cache.
-- 
2.44.0