NFS: Add a way to disable NFS v4.0 via KConfig

I introduce NFS4_MIN_MINOR_VERSION as a parallel to
NFS4_MAX_MINOR_VERSION to check if NFS v4.0 has been compiled in and
return an appropriate error if not.

Signed-off-by: Anna Schumaker <[e-mail]>

fs/nfs/Kconfig

···
 	help
 	  This option enables swapon to work on files located on NFS mounts.
 
+config NFS_V4_0
+	bool "NFS client support for NFSv4.0"
+	depends on NFS_V4
+	help
+	  This option enables support for minor version 0 of the NFSv4 protocol
+	  (RFC 3530) in the kernel's NFS client.
+
+	  If unsure, say N.
+
 config NFS_V4_1
 	bool "NFS client support for NFSv4.1"
 	depends on NFS_V4

fs/nfs/Makefile

···
 nfsv4-y := nfs4proc.o nfs4xdr.o nfs4state.o nfs4renewd.o nfs4super.o nfs4file.o \
 	  delegation.o nfs4idmap.o callback.o callback_xdr.o callback_proc.o \
 	  nfs4namespace.o nfs4getroot.o nfs4client.o nfs4session.o \
-	  dns_resolve.o nfs4trace.o nfs40proc.o nfs40client.o
+	  dns_resolve.o nfs4trace.o
 nfsv4-$(CONFIG_NFS_USE_LEGACY_DNS) += cache_lib.o
 nfsv4-$(CONFIG_SYSCTL)	+= nfs4sysctl.o
+nfsv4-$(CONFIG_NFS_V4_0)	+= nfs40client.o nfs40proc.o
 nfsv4-$(CONFIG_NFS_V4_1)	+= pnfs.o pnfs_dev.o pnfs_nfs.o
 nfsv4-$(CONFIG_NFS_V4_2)	+= nfs42proc.o nfs42xattr.o
 

fs/nfs/fs_context.c

···
 		ctx->mount_server.version = result.uint_32;
 		break;
 	case Opt_minorversion:
-		if (result.uint_32 > NFS4_MAX_MINOR_VERSION)
+		if (result.uint_32 < NFS4_MIN_MINOR_VERSION ||
+		    result.uint_32 > NFS4_MAX_MINOR_VERSION)
 			goto out_of_bounds;
 		ctx->minorversion = result.uint_32;
 		break;

fs/nfs/nfs4_fs.h

···
 #ifndef __LINUX_FS_NFS_NFS4_FS_H
 #define __LINUX_FS_NFS_NFS4_FS_H
 
+#if defined(CONFIG_NFS_V4_0)
+#define NFS4_MIN_MINOR_VERSION 0
+#else
+#define NFS4_MIN_MINOR_VERSION 1
+#endif
+
 #if defined(CONFIG_NFS_V4_2)
 #define NFS4_MAX_MINOR_VERSION 2
 #elif defined(CONFIG_NFS_V4_1)

fs/nfs/nfs4client.c

···
 	if (err)
 		goto error;
 
-	if (cl_init->minorversion > NFS4_MAX_MINOR_VERSION) {
+	if (cl_init->minorversion < NFS4_MIN_MINOR_VERSION ||
+	    cl_init->minorversion > NFS4_MAX_MINOR_VERSION) {
 		err = -EINVAL;
 		goto error;
 	}

fs/nfs/nfs4proc.c

···
 #endif
 
 const struct nfs4_minor_version_ops *nfs_v4_minor_ops[] = {
+#if defined(CONFIG_NFS_V4_0)
 	[0] = &nfs_v4_0_minor_ops,
+#endif /* CONFIG_NFS_V4_0 */
 #if defined(CONFIG_NFS_V4_1)
 	[1] = &nfs_v4_1_minor_ops,
 #endif

fs/nfs/nfs4state.c

···
 	switch (error) {
 	case 0:
 		break;
+#if IS_ENABLED(CONFIG_NFS_V4_0)
 	case -NFS4ERR_CB_PATH_DOWN:
 		nfs40_handle_cb_pathdown(clp);
 		break;
+#endif /* CONFIG_NFS_V4_0 */
 	case -NFS4ERR_NO_GRACE:
 		nfs4_state_end_reclaim_reboot(clp);
 		break;

fs/nfs/nfs4xdr.c

···
 	xdr_encode_hyper(p, nfs4_lock_length(args->fl));
 }
 
+#if defined(CONFIG_NFS_V4_0)
 static void encode_release_lockowner(struct xdr_stream *xdr, const struct nfs_lowner *lowner, struct compound_hdr *hdr)
 {
 	encode_op_hdr(xdr, OP_RELEASE_LOCKOWNER, decode_release_lockowner_maxsz, hdr);
 	encode_lockowner(xdr, lowner);
 }
+#endif /* CONFIG_NFS_V4_0 */
 
 static void encode_lookup(struct xdr_stream *xdr, const struct qstr *name, struct compound_hdr *hdr)
 {
···
 	encode_nops(&hdr);
 }
 
+#if defined(CONFIG_NFS_V4_0)
 static void nfs4_xdr_enc_release_lockowner(struct rpc_rqst *req,
 					   struct xdr_stream *xdr,
 					   const void *data)
···
 	encode_release_lockowner(xdr, &args->lock_owner, &hdr);
 	encode_nops(&hdr);
 }
+#endif /* CONFIG_NFS_V4_0 */
 
 /*
  * Encode a READLINK request
···
 /*
  * a RENEW request
  */
+#if defined(CONFIG_NFS_V4_0)
 static void nfs4_xdr_enc_renew(struct rpc_rqst *req, struct xdr_stream *xdr,
 			       const void *data)
 
···
 	encode_renew(xdr, clp->cl_clientid, &hdr);
 	encode_nops(&hdr);
 }
+#endif /* CONFIG_NFS_V4_0 */
 
 /*
  * a SETCLIENTID request
···
 	return status;
 }
 
+#if defined(CONFIG_NFS_V4_0)
 static int decode_release_lockowner(struct xdr_stream *xdr)
 {
 	return decode_op_hdr(xdr, OP_RELEASE_LOCKOWNER);
 }
+#endif /* CONFIG_NFS_V4_0 */
 
 static int decode_lookup(struct xdr_stream *xdr)
 {
···
 	return status;
 }
 
+#if defined(CONFIG_NFS_V4_0)
 static int nfs4_xdr_dec_release_lockowner(struct rpc_rqst *rqstp,
 					  struct xdr_stream *xdr, void *dummy)
 {
···
 		status = decode_release_lockowner(xdr);
 	return status;
 }
+#endif /* CONFIG_NFS_V4_0 */
 
 /*
  * Decode READLINK response
···
 /*
  * Decode RENEW response
  */
+#if defined(CONFIG_NFS_V4_0)
 static int nfs4_xdr_dec_renew(struct rpc_rqst *rqstp, struct xdr_stream *xdr,
 			      void *__unused)
 {
···
 		status = decode_renew(xdr);
 	return status;
 }
+#endif /* CONFIG_NFS_V4_0 */
 
 /*
  * Decode SETCLIENTID response
···
 	.p_name = #proc,	\
 }
 
+#if defined(CONFIG_NFS_V4_0)
+#define PROC40(proc, argtype, restype)				\
+	PROC(proc, argtype, restype)
+#else
+#define PROC40(proc, argtype, restype)				\
+	STUB(proc)
+#endif /* CONFIG_NFS_V4_0 */
+
 #if defined(CONFIG_NFS_V4_1)
 #define PROC41(proc, argtype, restype)				\
 	PROC(proc, argtype, restype)
···
 	PROC(CLOSE,		enc_close,		dec_close),
 	PROC(SETATTR,		enc_setattr,		dec_setattr),
 	PROC(FSINFO,		enc_fsinfo,		dec_fsinfo),
-	PROC(RENEW,		enc_renew,		dec_renew),
+	PROC40(RENEW,		enc_renew,		dec_renew),
 	PROC(SETCLIENTID,	enc_setclientid,	dec_setclientid),
 	PROC(SETCLIENTID_CONFIRM, enc_setclientid_confirm, dec_setclientid_confirm),
 	PROC(LOCK,		enc_lock,		dec_lock),
···
 	PROC(GETACL,		enc_getacl,		dec_getacl),
 	PROC(SETACL,		enc_setacl,		dec_setacl),
 	PROC(FS_LOCATIONS,	enc_fs_locations,	dec_fs_locations),
-	PROC(RELEASE_LOCKOWNER,	enc_release_lockowner,	dec_release_lockowner),
+	PROC40(RELEASE_LOCKOWNER,	enc_release_lockowner,	dec_release_lockowner),
 	PROC(SECINFO,		enc_secinfo,		dec_secinfo),
 	PROC(FSID_PRESENT,	enc_fsid_present,	dec_fsid_present),
 	PROC41(EXCHANGE_ID,	enc_exchange_id,	dec_exchange_id),