NFS: Add fs_context support.

Add filesystem context support to NFS, parsing the options in advance and
attaching the information to struct nfs_fs_context.  The highlights are:

 (*) Merge nfs_mount_info and nfs_clone_mount into nfs_fs_context.  This
     structure represents NFS's superblock config.

 (*) Make use of the VFS's parsing support to split comma-separated lists

 (*) Pin the NFS protocol module in the nfs_fs_context.

 (*) Attach supplementary error information to fs_context.  This has the
     downside that these strings must be static and can't be formatted.

 (*) Remove the auxiliary file_system_type structs since the information
     necessary can be conveyed in the nfs_fs_context struct instead.

 (*) Root mounts are made by duplicating the config for the requested mount
     so as to have the same parameters.  Submounts pick up their parameters
     from the parent superblock.

[AV -- retrans is u32, not string]
[SM -- Renamed cfg to ctx in a few functions in an earlier patch]
[SM -- Moved fs_context mount option parsing to an earlier patch]
[SM -- Moved fs_context error logging to a later patch]
[SM -- Fixed printks in nfs4_try_get_tree() and nfs4_get_referral_tree()]
[SM -- Added is_remount_fc() helper]
[SM -- Deferred some refactoring to a later patch]
[SM -- Fixed referral mounts, which were broken in the original patch]
[SM -- Fixed leak of nfs_fattr when fs_context is freed]
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/fs_context.c

@@ -3,6 +3,7 @@
  * linux/fs/nfs/fs_context.c
  *
  * Copyright (C) 1992 Rick Sladkey
+ * Conversion to new mount api Copyright (C) David Howells
  *
  * NFS mount handling.
  *
@@ -467,21 +468,31 @@ static int nfs_parse_version_string(struct nfs_fs_context *ctx,
 /*
  * Parse a single mount parameter.
  */
-static int nfs_fs_context_parse_param(struct nfs_fs_context *ctx,
+static int nfs_fs_context_parse_param(struct fs_context *fc,
 				      struct fs_parameter *param)
 {
 	struct fs_parse_result result;
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
 	unsigned short protofamily, mountfamily;
 	unsigned int len;
 	int ret, opt;
 
 	dfprintk(MOUNT, "NFS:   parsing nfs mount option '%s'\n", param->key);
 
-	opt = fs_parse(NULL, &nfs_fs_parameters, param, &result);
+	opt = fs_parse(fc, &nfs_fs_parameters, param, &result);
 	if (opt < 0)
 		return ctx->sloppy ? 1 : opt;
 
 	switch (opt) {
+	case Opt_source:
+		if (fc->source) {
+			dfprintk(MOUNT, "NFS: Multiple sources not supported\n");
+			return -EINVAL;
+		}
+		fc->source = param->string;
+		param->string = NULL;
+		break;
+
 		/*
 		 * boolean options:  foo/nofoo
 		 */
@@ -807,112 +818,6 @@ static int nfs_fs_context_parse_param(struct nfs_fs_context *ctx,
 	return -ERANGE;
 }
 
-/* cribbed from generic_parse_monolithic and vfs_parse_fs_string */
-static int nfs_fs_context_parse_option(struct nfs_fs_context *ctx, char *p)
-{
-	int ret;
-	char *key = p, *value;
-	size_t v_size = 0;
-	struct fs_parameter param;
-
-	memset(&param, 0, sizeof(param));
-	value = strchr(key, '=');
-	if (value && value != key) {
-		*value++ = 0;
-		v_size = strlen(value);
-	}
-	param.key = key;
-	param.type = fs_value_is_flag;
-	param.size = v_size;
-	if (v_size > 0) {
-		param.type = fs_value_is_string;
-		param.string = kmemdup_nul(value, v_size, GFP_KERNEL);
-		if (!param.string)
-			return -ENOMEM;
-	}
-	ret = nfs_fs_context_parse_param(ctx, &param);
-	kfree(param.string);
-	return ret;
-}
-
-/*
- * Error-check and convert a string of mount options from user space into
- * a data structure.  The whole mount string is processed; bad options are
- * skipped as they are encountered.  If there were no errors, return 1;
- * otherwise return 0 (zero).
- */
-int nfs_parse_mount_options(char *raw, struct nfs_fs_context *ctx)
-{
-	char *p;
-	int rc, sloppy = 0, invalid_option = 0;
-
-	if (!raw) {
-		dfprintk(MOUNT, "NFS: mount options string was NULL.\n");
-		return 1;
-	}
-	dfprintk(MOUNT, "NFS: nfs mount opts='%s'\n", raw);
-
-	rc = security_sb_eat_lsm_opts(raw, &ctx->lsm_opts);
-	if (rc)
-		goto out_security_failure;
-
-	while ((p = strsep(&raw, ",")) != NULL) {
-		if (!*p)
-			continue;
-		if (nfs_fs_context_parse_option(ctx, p) < 0)
-			invalid_option = true;
-	}
-
-	if (!sloppy && invalid_option)
-		return 0;
-
-	if (ctx->minorversion && ctx->version != 4)
-		goto out_minorversion_mismatch;
-
-	if (ctx->options & NFS_OPTION_MIGRATION &&
-	    (ctx->version != 4 || ctx->minorversion != 0))
-		goto out_migration_misuse;
-
-	/*
-	 * verify that any proto=/mountproto= options match the address
-	 * families in the addr=/mountaddr= options.
-	 */
-	if (ctx->protofamily != AF_UNSPEC &&
-	    ctx->protofamily != ctx->nfs_server.address.sa_family)
-		goto out_proto_mismatch;
-
-	if (ctx->mountfamily != AF_UNSPEC) {
-		if (ctx->mount_server.addrlen) {
-			if (ctx->mountfamily != ctx->mount_server.address.sa_family)
-				goto out_mountproto_mismatch;
-		} else {
-			if (ctx->mountfamily != ctx->nfs_server.address.sa_family)
-				goto out_mountproto_mismatch;
-		}
-	}
-
-	return 1;
-
-out_minorversion_mismatch:
-	printk(KERN_INFO "NFS: mount option vers=%u does not support "
-			 "minorversion=%u\n", ctx->version, ctx->minorversion);
-	return 0;
-out_mountproto_mismatch:
-	printk(KERN_INFO "NFS: mount server address does not match mountproto= "
-			 "option\n");
-	return 0;
-out_proto_mismatch:
-	printk(KERN_INFO "NFS: server address does not match proto= option\n");
-	return 0;
-out_migration_misuse:
-	printk(KERN_INFO
-		"NFS: 'migration' not supported for this NFS version\n");
-	return -EINVAL;
-out_security_failure:
-	printk(KERN_INFO "NFS: security options invalid: %d\n", rc);
-	return 0;
-}
-
 /*
  * Split "dev_name" into "hostname:export_path".
  *
@@ -990,6 +895,11 @@ static int nfs_parse_devname(struct nfs_fs_context *ctx,
 	return -ENAMETOOLONG;
 }
 
+static inline bool is_remount_fc(struct fs_context *fc)
+{
+	return fc->root != NULL;
+}
+
 /*
  * Parse monolithic NFS2/NFS3 mount data
  * - fills in the mount root filehandle
@@ -1006,12 +916,11 @@ static int nfs_parse_devname(struct nfs_fs_context *ctx,
  * + breaking back: trying proto=udp after proto=tcp, v2 after v3,
  *   mountproto=tcp after mountproto=udp, and so on
  */
-static int nfs23_validate_mount_data(void *options,
-				     struct nfs_fs_context *ctx,
-				     struct nfs_fh *mntfh,
-				     const char *dev_name)
+static int nfs23_parse_monolithic(struct fs_context *fc,
+				  struct nfs_mount_data *data)
 {
-	struct nfs_mount_data *data = (struct nfs_mount_data *)options;
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
+	struct nfs_fh *mntfh = ctx->mount_info.mntfh;
 	struct sockaddr *sap = (struct sockaddr *)&ctx->nfs_server.address;
 	int extra_flags = NFS_MOUNT_LEGACY_INTERFACE;
 
@@ -1083,6 +992,9 @@ static int nfs23_validate_mount_data(void *options,
 			ctx->nfs_server.protocol = XPRT_TRANSPORT_UDP;
 		/* N.B. caller will free nfs_server.hostname in all cases */
 		ctx->nfs_server.hostname = kstrdup(data->hostname, GFP_KERNEL);
+		if (!ctx->nfs_server.hostname)
+			goto out_nomem;
+
 		ctx->namlen		= data->namlen;
 		ctx->bsize		= data->bsize;
 
@@ -1090,8 +1002,6 @@ static int nfs23_validate_mount_data(void *options,
 			ctx->selected_flavor = data->pseudoflavor;
 		else
 			ctx->selected_flavor = RPC_AUTH_UNIX;
-		if (!ctx->nfs_server.hostname)
-			goto out_nomem;
 
 		if (!(data->flags & NFS_MOUNT_NONLM))
 			ctx->flags &= ~(NFS_MOUNT_LOCAL_FLOCK|
@@ -1109,12 +1019,13 @@ static int nfs23_validate_mount_data(void *options,
 		 */
 		if (data->context[0]){
 #ifdef CONFIG_SECURITY_SELINUX
-			int rc;
+			int ret;
+
 			data->context[NFS_MAX_CONTEXT_LEN] = '\0';
-			rc = security_add_mnt_opt("context", data->context,
-					strlen(data->context), ctx->lsm_opts);
-			if (rc)
-				return rc;
+			ret = vfs_parse_fs_string(fc, "context",
+						  data->context, strlen(data->context));
+			if (ret < 0)
+				return ret;
 #else
 			return -EINVAL;
 #endif
@@ -1122,12 +1033,20 @@ static int nfs23_validate_mount_data(void *options,
 
 		break;
 	default:
-		return NFS_TEXT_DATA;
+		goto generic;
 	}
 
+	ctx->skip_reconfig_option_check = true;
 	return 0;
 
+generic:
+	return generic_parse_monolithic(fc, data);
+
 out_no_data:
+	if (is_remount_fc(fc)) {
+		ctx->skip_reconfig_option_check = true;
+		return 0;
+	}
 	dfprintk(MOUNT, "NFS: mount program didn't pass any mount data\n");
 	return -EINVAL;
 
@@ -1163,12 +1082,11 @@ static void nfs4_validate_mount_flags(struct nfs_fs_context *ctx)
 /*
  * Validate NFSv4 mount options
  */
-static int nfs4_validate_mount_data(void *options,
-				    struct nfs_fs_context *ctx,
-				    const char *dev_name)
+static int nfs4_parse_monolithic(struct fs_context *fc,
+				 struct nfs4_mount_data *data)
 {
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
 	struct sockaddr *sap = (struct sockaddr *)&ctx->nfs_server.address;
-	struct nfs4_mount_data *data = (struct nfs4_mount_data *)options;
 	char *c;
 
 	if (data == NULL)
@@ -1218,7 +1136,7 @@ static int nfs4_validate_mount_data(void *options,
 		ctx->client_address = c;
 
 		/*
-		 * Translate to nfs_fs_context, which nfs4_fill_super
+		 * Translate to nfs_fs_context, which nfs_fill_super
 		 * can deal with.
 		 */
 
@@ -1238,12 +1156,20 @@ static int nfs4_validate_mount_data(void *options,
 
 		break;
 	default:
-		return NFS_TEXT_DATA;
+		goto generic;
 	}
 
+	ctx->skip_reconfig_option_check = true;
 	return 0;
 
+generic:
+	return generic_parse_monolithic(fc, data);
+
 out_no_data:
+	if (is_remount_fc(fc)) {
+		ctx->skip_reconfig_option_check = true;
+		return 0;
+	}
 	dfprintk(MOUNT, "NFS4: mount program didn't pass any mount data\n");
 	return -EINVAL;
 
@@ -1260,39 +1186,66 @@ static int nfs4_validate_mount_data(void *options,
 	dfprintk(MOUNT, "NFSv4: Unsupported transport protocol udp\n");
 	return -EINVAL;
 }
+#endif
 
-int nfs_validate_mount_data(struct file_system_type *fs_type,
-			    void *options,
-			    struct nfs_fs_context *ctx,
-			    struct nfs_fh *mntfh,
-			    const char *dev_name)
-{
-	if (fs_type == &nfs_fs_type)
-		return nfs23_validate_mount_data(options, ctx, mntfh, dev_name);
-	return nfs4_validate_mount_data(options, ctx, dev_name);
-}
-#else
-int nfs_validate_mount_data(struct file_system_type *fs_type,
-			    void *options,
-			    struct nfs_fs_context *ctx,
-			    struct nfs_fh *mntfh,
-			    const char *dev_name)
+/*
+ * Parse a monolithic block of data from sys_mount().
+ */
+static int nfs_fs_context_parse_monolithic(struct fs_context *fc,
+					   void *data)
 {
-	return nfs23_validate_mount_data(options, ctx, mntfh, dev_name);
-}
+	if (fc->fs_type == &nfs_fs_type)
+		return nfs23_parse_monolithic(fc, data);
+
+#if IS_ENABLED(CONFIG_NFS_V4)
+	if (fc->fs_type == &nfs4_fs_type)
+		return nfs4_parse_monolithic(fc, data);
 #endif
 
-int nfs_validate_text_mount_data(void *options,
-				 struct nfs_fs_context *ctx,
-				 const char *dev_name)
+	dfprintk(MOUNT, "NFS: Unsupported monolithic data version\n");
+	return -EINVAL;
+}
+
+/*
+ * Validate the preparsed information in the config.
+ */
+static int nfs_fs_context_validate(struct fs_context *fc)
 {
-	int port = 0;
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
+	struct nfs_subversion *nfs_mod;
+	struct sockaddr *sap = (struct sockaddr *)&ctx->nfs_server.address;
 	int max_namelen = PAGE_SIZE;
 	int max_pathlen = NFS_MAXPATHLEN;
-	struct sockaddr *sap = (struct sockaddr *)&ctx->nfs_server.address;
+	int port = 0;
+	int ret;
 
-	if (nfs_parse_mount_options((char *)options, ctx) == 0)
-		return -EINVAL;
+	if (!fc->source)
+		goto out_no_device_name;
+
+	/* Check for sanity first. */
+	if (ctx->minorversion && ctx->version != 4)
+		goto out_minorversion_mismatch;
+
+	if (ctx->options & NFS_OPTION_MIGRATION &&
+	    (ctx->version != 4 || ctx->minorversion != 0))
+		goto out_migration_misuse;
+
+	/* Verify that any proto=/mountproto= options match the address
+	 * families in the addr=/mountaddr= options.
+	 */
+	if (ctx->protofamily != AF_UNSPEC &&
+	    ctx->protofamily != ctx->nfs_server.address.sa_family)
+		goto out_proto_mismatch;
+
+	if (ctx->mountfamily != AF_UNSPEC) {
+		if (ctx->mount_server.addrlen) {
+			if (ctx->mountfamily != ctx->mount_server.address.sa_family)
+				goto out_mountproto_mismatch;
+		} else {
+			if (ctx->mountfamily != ctx->nfs_server.address.sa_family)
+				goto out_mountproto_mismatch;
+		}
+	}
 
 	if (!nfs_verify_server_address(sap))
 		goto out_no_address;
@@ -1320,8 +1273,24 @@ int nfs_validate_text_mount_data(void *options,
 
 	nfs_set_port(sap, &ctx->nfs_server.port, port);
 
-	return nfs_parse_devname(ctx, dev_name, max_namelen, max_pathlen);
+	ret = nfs_parse_devname(ctx, fc->source, max_namelen, max_pathlen);
+	if (ret < 0)
+		return ret;
+
+	/* Load the NFS protocol module if we haven't done so yet */
+	if (!ctx->mount_info.nfs_mod) {
+		nfs_mod = get_nfs_version(ctx->version);
+		if (IS_ERR(nfs_mod)) {
+			ret = PTR_ERR(nfs_mod);
+			goto out_version_unavailable;
+		}
+		ctx->mount_info.nfs_mod = nfs_mod;
+	}
+	return 0;
 
+out_no_device_name:
+	dfprintk(MOUNT, "NFS: Device name not specified\n");
+	return -EINVAL;
 #if !IS_ENABLED(CONFIG_NFS_V4)
 out_v4_not_compiled:
 	dfprintk(MOUNT, "NFS: NFSv4 is not compiled into kernel\n");
@@ -1331,8 +1300,201 @@ int nfs_validate_text_mount_data(void *options,
 	dfprintk(MOUNT, "NFSv4: Unsupported transport protocol udp\n");
 	return -EINVAL;
 #endif /* !CONFIG_NFS_V4 */
-
 out_no_address:
 	dfprintk(MOUNT, "NFS: mount program didn't pass remote address\n");
 	return -EINVAL;
+out_mountproto_mismatch:
+	dfprintk(MOUNT, "NFS: Mount server address does not match mountproto= option\n");
+	return -EINVAL;
+out_proto_mismatch:
+	dfprintk(MOUNT, "NFS: Server address does not match proto= option\n");
+	return -EINVAL;
+out_minorversion_mismatch:
+	dfprintk(MOUNT, "NFS: Mount option vers=%u does not support minorversion=%u\n",
+			  ctx->version, ctx->minorversion);
+	return -EINVAL;
+out_migration_misuse:
+	dfprintk(MOUNT, "NFS: 'Migration' not supported for this NFS version\n");
+	return -EINVAL;
+out_version_unavailable:
+	dfprintk(MOUNT, "NFS: Version unavailable\n");
+	return ret;
+}
+
+/*
+ * Create an NFS superblock by the appropriate method.
+ */
+static int nfs_get_tree(struct fs_context *fc)
+{
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
+	int err = nfs_fs_context_validate(fc);
+
+	if (err)
+		return err;
+	if (!ctx->internal)
+		return ctx->mount_info.nfs_mod->rpc_ops->try_get_tree(fc);
+	else
+		return nfs_get_tree_common(fc);
 }
+
+/*
+ * Handle duplication of a configuration.  The caller copied *src into *sc, but
+ * it can't deal with resource pointers in the filesystem context, so we have
+ * to do that.  We need to clear pointers, copy data or get extra refs as
+ * appropriate.
+ */
+static int nfs_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc)
+{
+	struct nfs_fs_context *src = nfs_fc2context(src_fc), *ctx;
+
+	ctx = kmemdup(src, sizeof(struct nfs_fs_context), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+
+	ctx->mount_info.mntfh = nfs_alloc_fhandle();
+	if (!ctx->mount_info.mntfh) {
+		kfree(ctx);
+		return -ENOMEM;
+	}
+	nfs_copy_fh(ctx->mount_info.mntfh, src->mount_info.mntfh);
+
+	__module_get(ctx->mount_info.nfs_mod->owner);
+	ctx->client_address		= NULL;
+	ctx->mount_server.hostname	= NULL;
+	ctx->nfs_server.export_path	= NULL;
+	ctx->nfs_server.hostname	= NULL;
+	ctx->fscache_uniq		= NULL;
+	ctx->clone_data.addr		= NULL;
+	ctx->clone_data.fattr		= NULL;
+	fc->fs_private = ctx;
+	return 0;
+}
+
+static void nfs_fs_context_free(struct fs_context *fc)
+{
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
+
+	if (ctx) {
+		if (ctx->mount_info.server)
+			nfs_free_server(ctx->mount_info.server);
+		if (ctx->mount_info.nfs_mod)
+			put_nfs_version(ctx->mount_info.nfs_mod);
+		kfree(ctx->client_address);
+		kfree(ctx->mount_server.hostname);
+		kfree(ctx->nfs_server.export_path);
+		kfree(ctx->nfs_server.hostname);
+		kfree(ctx->fscache_uniq);
+		nfs_free_fhandle(ctx->mount_info.mntfh);
+		kfree(ctx->clone_data.addr);
+		nfs_free_fattr(ctx->clone_data.fattr);
+		kfree(ctx);
+	}
+}
+
+static const struct fs_context_operations nfs_fs_context_ops = {
+	.free			= nfs_fs_context_free,
+	.dup			= nfs_fs_context_dup,
+	.parse_param		= nfs_fs_context_parse_param,
+	.parse_monolithic	= nfs_fs_context_parse_monolithic,
+	.get_tree		= nfs_get_tree,
+	.reconfigure		= nfs_reconfigure,
+};
+
+/*
+ * Prepare superblock configuration.  We use the namespaces attached to the
+ * context.  This may be the current process's namespaces, or it may be a
+ * container's namespaces.
+ */
+static int nfs_init_fs_context(struct fs_context *fc)
+{
+	struct nfs_fs_context *ctx;
+
+	ctx = kzalloc(sizeof(struct nfs_fs_context), GFP_KERNEL);
+	if (unlikely(!ctx))
+		return -ENOMEM;
+
+	ctx->mount_info.ctx = ctx;
+	ctx->mount_info.mntfh = nfs_alloc_fhandle();
+	if (unlikely(!ctx->mount_info.mntfh)) {
+		kfree(ctx);
+		return -ENOMEM;
+	}
+
+	ctx->protofamily	= AF_UNSPEC;
+	ctx->mountfamily	= AF_UNSPEC;
+	ctx->mount_server.port	= NFS_UNSPEC_PORT;
+
+	if (fc->root) {
+		/* reconfigure, start with the current config */
+		struct nfs_server *nfss = fc->root->d_sb->s_fs_info;
+		struct net *net = nfss->nfs_client->cl_net;
+
+		ctx->flags		= nfss->flags;
+		ctx->rsize		= nfss->rsize;
+		ctx->wsize		= nfss->wsize;
+		ctx->retrans		= nfss->client->cl_timeout->to_retries;
+		ctx->selected_flavor	= nfss->client->cl_auth->au_flavor;
+		ctx->acregmin		= nfss->acregmin / HZ;
+		ctx->acregmax		= nfss->acregmax / HZ;
+		ctx->acdirmin		= nfss->acdirmin / HZ;
+		ctx->acdirmax		= nfss->acdirmax / HZ;
+		ctx->timeo		= 10U * nfss->client->cl_timeout->to_initval / HZ;
+		ctx->nfs_server.port	= nfss->port;
+		ctx->nfs_server.addrlen	= nfss->nfs_client->cl_addrlen;
+		ctx->version		= nfss->nfs_client->rpc_ops->version;
+		ctx->minorversion	= nfss->nfs_client->cl_minorversion;
+
+		memcpy(&ctx->nfs_server.address, &nfss->nfs_client->cl_addr,
+			ctx->nfs_server.addrlen);
+
+		if (fc->net_ns != net) {
+			put_net(fc->net_ns);
+			fc->net_ns = get_net(net);
+		}
+
+		ctx->mount_info.nfs_mod = nfss->nfs_client->cl_nfs_mod;
+		__module_get(ctx->mount_info.nfs_mod->owner);
+	} else {
+		/* defaults */
+		ctx->timeo		= NFS_UNSPEC_TIMEO;
+		ctx->retrans		= NFS_UNSPEC_RETRANS;
+		ctx->acregmin		= NFS_DEF_ACREGMIN;
+		ctx->acregmax		= NFS_DEF_ACREGMAX;
+		ctx->acdirmin		= NFS_DEF_ACDIRMIN;
+		ctx->acdirmax		= NFS_DEF_ACDIRMAX;
+		ctx->nfs_server.port	= NFS_UNSPEC_PORT;
+		ctx->nfs_server.protocol = XPRT_TRANSPORT_TCP;
+		ctx->selected_flavor	= RPC_AUTH_MAXFLAVOR;
+		ctx->minorversion	= 0;
+		ctx->need_mount		= true;
+	}
+	ctx->net = fc->net_ns;
+	fc->fs_private = ctx;
+	fc->ops = &nfs_fs_context_ops;
+	return 0;
+}
+
+struct file_system_type nfs_fs_type = {
+	.owner			= THIS_MODULE,
+	.name			= "nfs",
+	.init_fs_context	= nfs_init_fs_context,
+	.parameters		= &nfs_fs_parameters,
+	.kill_sb		= nfs_kill_super,
+	.fs_flags		= FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
+};
+MODULE_ALIAS_FS("nfs");
+EXPORT_SYMBOL_GPL(nfs_fs_type);
+
+#if IS_ENABLED(CONFIG_NFS_V4)
+struct file_system_type nfs4_fs_type = {
+	.owner			= THIS_MODULE,
+	.name			= "nfs4",
+	.init_fs_context	= nfs_init_fs_context,
+	.parameters		= &nfs_fs_parameters,
+	.kill_sb		= nfs_kill_super,
+	.fs_flags		= FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
+};
+MODULE_ALIAS_FS("nfs4");
+MODULE_ALIAS("nfs4");
+EXPORT_SYMBOL_GPL(nfs4_fs_type);
+#endif /* CONFIG_NFS_V4 */

fs/nfs/internal.h

@@ -4,7 +4,7 @@
  */
 
 #include "nfs4_fs.h"
-#include <linux/mount.h>
+#include <linux/fs_context.h>
 #include <linux/security.h>
 #include <linux/crc32.h>
 #include <linux/sunrpc/addr.h>
@@ -16,6 +16,7 @@
 extern const struct export_operations nfs_export_ops;
 
 struct nfs_string;
+struct nfs_pageio_descriptor;
 
 static inline void nfs_attr_check_mountpoint(struct super_block *parent, struct nfs_fattr *fattr)
 {
@@ -34,12 +35,13 @@ static inline int nfs_attr_use_mounted_on_fileid(struct nfs_fattr *fattr)
 
 struct nfs_clone_mount {
 	const struct super_block *sb;
-	const struct dentry *dentry;
+	struct dentry *dentry;
 	char *hostname;
 	char *mnt_path;
 	struct sockaddr *addr;
 	size_t addrlen;
 	rpc_authflavor_t authflavor;
+	struct nfs_fattr *fattr;
 };
 
 /*
@@ -78,10 +80,23 @@ struct nfs_client_initdata {
 	const struct cred *cred;
 };
 
+struct nfs_mount_info {
+	unsigned int inherited_bsize;
+	struct nfs_fs_context *ctx;
+	struct nfs_clone_mount *cloned;
+	struct nfs_server *server;
+	struct nfs_fh *mntfh;
+	struct nfs_subversion *nfs_mod;
+};
+
 /*
  * In-kernel mount arguments
  */
 struct nfs_fs_context {
+	bool			internal;
+	bool			skip_reconfig_option_check;
+	bool			need_mount;
+	bool			sloppy;
 	unsigned int		flags;		/* NFS{,4}_MOUNT_* flags */
 	unsigned int		rsize, wsize;
 	unsigned int		timeo, retrans;
@@ -98,8 +113,6 @@ struct nfs_fs_context {
 	char			*fscache_uniq;
 	unsigned short		protofamily;
 	unsigned short		mountfamily;
-	bool			need_mount;
-	bool			sloppy;
 
 	struct {
 		union {
@@ -124,14 +137,23 @@ struct nfs_fs_context {
 		int			port;
 		unsigned short		protocol;
 		unsigned short		nconnect;
+		unsigned short		export_path_len;
 	} nfs_server;
 
 	void			*lsm_opts;
 	struct net		*net;
 
 	char			buf[32];	/* Parse buffer */
+
+	struct nfs_mount_info	mount_info;
+	struct nfs_clone_mount	clone_data;
 };
 
+static inline struct nfs_fs_context *nfs_fc2context(const struct fs_context *fc)
+{
+	return fc->fs_private;
+}
+
 /* mount_clnt.c */
 struct nfs_mount_request {
 	struct sockaddr		*sap;
@@ -147,15 +169,6 @@ struct nfs_mount_request {
 	struct net		*net;
 };
 
-struct nfs_mount_info {
-	unsigned int inherited_bsize;
-	struct nfs_fs_context *ctx;
-	struct nfs_clone_mount *cloned;
-	struct nfs_server *server;
-	struct nfs_fh *mntfh;
-	struct nfs_subversion *nfs_mod;
-};
-
 extern int nfs_mount(struct nfs_mount_request *info);
 extern void nfs_umount(const struct nfs_mount_request *info);
 
@@ -235,22 +248,8 @@ static inline void nfs_fs_proc_exit(void)
 extern const struct svc_version nfs4_callback_version1;
 extern const struct svc_version nfs4_callback_version4;
 
-struct nfs_pageio_descriptor;
-
-/* mount.c */
-#define NFS_TEXT_DATA		1
-
-extern struct nfs_fs_context *nfs_alloc_parsed_mount_data(void);
-extern void nfs_free_parsed_mount_data(struct nfs_fs_context *ctx);
-extern int nfs_parse_mount_options(char *raw, struct nfs_fs_context *ctx);
-extern int nfs_validate_mount_data(struct file_system_type *fs_type,
-				   void *options,
-				   struct nfs_fs_context *ctx,
-				   struct nfs_fh *mntfh,
-				   const char *dev_name);
-extern int nfs_validate_text_mount_data(void *options,
-					struct nfs_fs_context *ctx,
-					const char *dev_name);
+/* fs_context.c */
+extern struct file_system_type nfs_fs_type;
 
 /* pagelist.c */
 extern int __init nfs_init_nfspagecache(void);
@@ -411,14 +410,9 @@ extern int nfs_wait_atomic_killable(atomic_t *p, unsigned int mode);
 
 /* super.c */
 extern const struct super_operations nfs_sops;
-extern struct file_system_type nfs_fs_type;
-extern struct file_system_type nfs_prepared_fs_type;
-#if IS_ENABLED(CONFIG_NFS_V4)
-extern struct file_system_type nfs4_referral_fs_type;
-#endif
 bool nfs_auth_info_match(const struct nfs_auth_info *, rpc_authflavor_t);
-struct dentry *nfs_try_mount(int, const char *, struct nfs_mount_info *);
-struct dentry *nfs_fs_mount(struct file_system_type *, int, const char *, void *);
+int nfs_try_get_tree(struct fs_context *);
+int nfs_get_tree_common(struct fs_context *);
 void nfs_kill_super(struct super_block *);
 
 extern struct rpc_stat nfs_rpcstat;
@@ -446,10 +440,8 @@ static inline bool nfs_file_io_is_buffered(struct nfs_inode *nfsi)
 extern char *nfs_path(char **p, struct dentry *dentry,
 		      char *buffer, ssize_t buflen, unsigned flags);
 extern struct vfsmount *nfs_d_automount(struct path *path);
-struct vfsmount *nfs_submount(struct nfs_server *, struct dentry *,
-			      struct nfs_fh *, struct nfs_fattr *);
-struct vfsmount *nfs_do_submount(struct dentry *, struct nfs_fh *,
-				 struct nfs_fattr *, rpc_authflavor_t);
+int nfs_submount(struct fs_context *, struct nfs_server *);
+int nfs_do_submount(struct fs_context *);
 
 /* getroot.c */
 extern struct dentry *nfs_get_root(struct super_block *, struct nfs_fh *,
@@ -476,7 +468,7 @@ int  nfs_show_options(struct seq_file *, struct dentry *);
 int  nfs_show_devname(struct seq_file *, struct dentry *);
 int  nfs_show_path(struct seq_file *, struct dentry *);
 int  nfs_show_stats(struct seq_file *, struct dentry *);
-int nfs_remount(struct super_block *sb, int *flags, char *raw_data);
+int  nfs_reconfigure(struct fs_context *);
 
 /* write.c */
 extern void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,

fs/nfs/namespace.c

@@ -140,34 +140,65 @@ EXPORT_SYMBOL_GPL(nfs_path);
  */
 struct vfsmount *nfs_d_automount(struct path *path)
 {
-	struct vfsmount *mnt;
+	struct nfs_fs_context *ctx;
+	struct fs_context *fc;
+	struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 	struct nfs_server *server = NFS_SERVER(d_inode(path->dentry));
-	struct nfs_fh *fh = NULL;
-	struct nfs_fattr *fattr = NULL;
+	struct nfs_client *client = server->nfs_client;
+	int ret;
 
 	if (IS_ROOT(path->dentry))
 		return ERR_PTR(-ESTALE);
 
-	mnt = ERR_PTR(-ENOMEM);
-	fh = nfs_alloc_fhandle();
-	fattr = nfs_alloc_fattr();
-	if (fh == NULL || fattr == NULL)
-		goto out;
+	/* Open a new filesystem context, transferring parameters from the
+	 * parent superblock, including the network namespace.
+	 */
+	fc = fs_context_for_submount(&nfs_fs_type, path->dentry);
+	if (IS_ERR(fc))
+		return ERR_CAST(fc);
 
-	mnt = server->nfs_client->rpc_ops->submount(server, path->dentry, fh, fattr);
+	ctx = nfs_fc2context(fc);
+	ctx->clone_data.dentry	= path->dentry;
+	ctx->clone_data.sb	= path->dentry->d_sb;
+	ctx->clone_data.fattr	= nfs_alloc_fattr();
+	if (!ctx->clone_data.fattr)
+		goto out_fc;
+
+	if (fc->net_ns != client->cl_net) {
+		put_net(fc->net_ns);
+		fc->net_ns = get_net(client->cl_net);
+	}
+
+	/* for submounts we want the same server; referrals will reassign */
+	memcpy(&ctx->nfs_server.address, &client->cl_addr, client->cl_addrlen);
+	ctx->nfs_server.addrlen	= client->cl_addrlen;
+	ctx->nfs_server.port	= server->port;
+
+	ctx->version		= client->rpc_ops->version;
+	ctx->minorversion	= client->cl_minorversion;
+	ctx->mount_info.nfs_mod	= client->cl_nfs_mod;
+	__module_get(ctx->mount_info.nfs_mod->owner);
+
+	ret = client->rpc_ops->submount(fc, server);
+	if (ret < 0) {
+		mnt = ERR_PTR(ret);
+		goto out_fc;
+	}
+
+	up_write(&fc->root->d_sb->s_umount);
+	mnt = vfs_create_mount(fc);
 	if (IS_ERR(mnt))
-		goto out;
+		goto out_fc;
 
 	if (nfs_mountpoint_expiry_timeout < 0)
-		goto out;
+		goto out_fc;
 
 	mntget(mnt); /* prevent immediate expiration */
 	mnt_set_expiry(mnt, &nfs_automount_list);
 	schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
 
-out:
-	nfs_free_fattr(fattr);
-	nfs_free_fhandle(fh);
+out_fc:
+	put_fs_context(fc);
 	return mnt;
 }
 
@@ -222,61 +253,62 @@ void nfs_release_automount_timer(void)
  * @authflavor: security flavor to use when performing the mount
  *
  */
-struct vfsmount *nfs_do_submount(struct dentry *dentry, struct nfs_fh *fh,
-				 struct nfs_fattr *fattr, rpc_authflavor_t authflavor)
+int nfs_do_submount(struct fs_context *fc)
 {
-	struct super_block *sb = dentry->d_sb;
-	struct nfs_clone_mount mountdata = {
-		.sb = sb,
-		.dentry = dentry,
-		.authflavor = authflavor,
-	};
-	struct nfs_mount_info mount_info = {
-		.inherited_bsize = sb->s_blocksize_bits,
-		.cloned = &mountdata,
-		.mntfh = fh,
-		.nfs_mod = NFS_SB(sb)->nfs_client->cl_nfs_mod,
-	};
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
+	struct dentry *dentry = ctx->clone_data.dentry;
 	struct nfs_server *server;
-	struct vfsmount *mnt;
-	char *page = (char *) __get_free_page(GFP_USER);
-	char *devname;
+	char *buffer, *p;
+	int ret;
 
-	if (page == NULL)
-		return ERR_PTR(-ENOMEM);
+	/* create a new volume representation */
+	server = ctx->mount_info.nfs_mod->rpc_ops->clone_server(NFS_SB(ctx->clone_data.sb),
+						     ctx->mount_info.mntfh,
+						     ctx->clone_data.fattr,
+						     ctx->selected_flavor);
 
-	server = mount_info.nfs_mod->rpc_ops->clone_server(NFS_SB(sb), fh,
-							   fattr, authflavor);
 	if (IS_ERR(server))
-		return ERR_CAST(server);
+		return PTR_ERR(server);
 
-	mount_info.server = server;
+	ctx->mount_info.server = server;
 
-	devname = nfs_devname(dentry, page, PAGE_SIZE);
-	if (IS_ERR(devname))
-		mnt = ERR_CAST(devname);
-	else
-		mnt = vfs_submount(dentry, &nfs_prepared_fs_type, devname, &mount_info);
+	buffer = kmalloc(4096, GFP_USER);
+	if (!buffer)
+		return -ENOMEM;
 
-	if (mount_info.server)
-		nfs_free_server(mount_info.server);
-	free_page((unsigned long)page);
-	return mnt;
+	ctx->internal		= true;
+	ctx->mount_info.inherited_bsize = ctx->clone_data.sb->s_blocksize_bits;
+
+	p = nfs_devname(dentry, buffer, 4096);
+	if (IS_ERR(p)) {
+		dprintk("NFS: Couldn't determine submount pathname\n");
+		ret = PTR_ERR(p);
+	} else {
+		ret = vfs_parse_fs_string(fc, "source", p, buffer + 4096 - p);
+		if (!ret)
+			ret = vfs_get_tree(fc);
+	}
+	kfree(buffer);
+	return ret;
 }
 EXPORT_SYMBOL_GPL(nfs_do_submount);
 
-struct vfsmount *nfs_submount(struct nfs_server *server, struct dentry *dentry,
-			      struct nfs_fh *fh, struct nfs_fattr *fattr)
+int nfs_submount(struct fs_context *fc, struct nfs_server *server)
 {
-	int err;
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
+	struct dentry *dentry = ctx->clone_data.dentry;
 	struct dentry *parent = dget_parent(dentry);
+	int err;
 
 	/* Look it up again to get its attributes */
-	err = server->nfs_client->rpc_ops->lookup(d_inode(parent), &dentry->d_name, fh, fattr, NULL);
+	err = server->nfs_client->rpc_ops->lookup(d_inode(parent), &dentry->d_name,
+						  ctx->mount_info.mntfh, ctx->clone_data.fattr,
+						  NULL);
 	dput(parent);
 	if (err != 0)
-		return ERR_PTR(err);
+		return err;
 
-	return nfs_do_submount(dentry, fh, fattr, server->client->cl_auth->au_flavor);
+	ctx->selected_flavor = server->client->cl_auth->au_flavor;
+	return nfs_do_submount(fc);
 }
 EXPORT_SYMBOL_GPL(nfs_submount);

fs/nfs/nfs3proc.c

@@ -990,7 +990,7 @@ const struct nfs_rpc_ops nfs_v3_clientops = {
 	.nlmclnt_ops	= &nlmclnt_fl_close_lock_ops,
 	.getroot	= nfs3_proc_get_root,
 	.submount	= nfs_submount,
-	.try_mount	= nfs_try_mount,
+	.try_get_tree	= nfs_try_get_tree,
 	.getattr	= nfs3_proc_getattr,
 	.setattr	= nfs3_proc_setattr,
 	.lookup		= nfs3_proc_lookup,

fs/nfs/nfs4_fs.h

@@ -268,14 +268,13 @@ extern const struct dentry_operations nfs4_dentry_operations;
 int nfs_atomic_open(struct inode *, struct dentry *, struct file *,
 		    unsigned, umode_t);
 
-/* super.c */
+/* fs_context.c */
 extern struct file_system_type nfs4_fs_type;
 
 /* nfs4namespace.c */
 struct rpc_clnt *nfs4_negotiate_security(struct rpc_clnt *, struct inode *,
 					 const struct qstr *);
-struct vfsmount *nfs4_submount(struct nfs_server *, struct dentry *,
-			       struct nfs_fh *, struct nfs_fattr *);
+int nfs4_submount(struct fs_context *, struct nfs_server *);
 int nfs4_replace_transport(struct nfs_server *server,
 				const struct nfs4_fs_locations *locations);
 
@@ -526,7 +525,6 @@ extern const nfs4_stateid invalid_stateid;
 /* nfs4super.c */
 struct nfs_mount_info;
 extern struct nfs_subversion nfs_v4;
-struct dentry *nfs4_try_mount(int, const char *, struct nfs_mount_info *);
 extern bool nfs4_disable_idmapping;
 extern unsigned short max_session_slots;
 extern unsigned short max_session_cb_slots;
@@ -536,6 +534,9 @@ extern bool recover_lost_locks;
 #define NFS4_CLIENT_ID_UNIQ_LEN		(64)
 extern char nfs4_client_id_uniquifier[NFS4_CLIENT_ID_UNIQ_LEN];
 
+extern int nfs4_try_get_tree(struct fs_context *);
+extern int nfs4_get_referral_tree(struct fs_context *);
+
 /* nfs4sysctl.c */
 #ifdef CONFIG_SYSCTL
 int nfs4_register_sysctl(void);

fs/nfs/nfs4file.c

@@ -7,6 +7,7 @@
 #include <linux/fs.h>
 #include <linux/file.h>
 #include <linux/falloc.h>
+#include <linux/mount.h>
 #include <linux/nfs_fs.h>
 #include "delegation.h"
 #include "internal.h"

fs/nfs/nfs4namespace.c

@@ -8,6 +8,7 @@
  * NFSv4 namespace
  */
 
+#include <linux/module.h>
 #include <linux/dcache.h>
 #include <linux/mount.h>
 #include <linux/namei.h>
@@ -21,37 +22,64 @@
 #include <linux/inet.h>
 #include "internal.h"
 #include "nfs4_fs.h"
+#include "nfs.h"
 #include "dns_resolve.h"
 
 #define NFSDBG_FACILITY		NFSDBG_VFS
 
+/*
+ * Work out the length that an NFSv4 path would render to as a standard posix
+ * path, with a leading slash but no terminating slash.
+ */
+static ssize_t nfs4_pathname_len(const struct nfs4_pathname *pathname)
+{
+	ssize_t len = 0;
+	int i;
+
+	for (i = 0; i < pathname->ncomponents; i++) {
+		const struct nfs4_string *component = &pathname->components[i];
+
+		if (component->len > NAME_MAX)
+			goto too_long;
+		len += 1 + component->len; /* Adding "/foo" */
+		if (len > PATH_MAX)
+			goto too_long;
+	}
+	return len;
+
+too_long:
+	return -ENAMETOOLONG;
+}
+
 /*
  * Convert the NFSv4 pathname components into a standard posix path.
- *
- * Note that the resulting string will be placed at the end of the buffer
  */
-static inline char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
-					 char *buffer, ssize_t buflen)
+static char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
+				  unsigned short *_len)
 {
-	char *end = buffer + buflen;
-	int n;
+	ssize_t len;
+	char *buf, *p;
+	int i;
+
+	len = nfs4_pathname_len(pathname);
+	if (len < 0)
+		return ERR_PTR(len);
+	*_len = len;
+
+	p = buf = kmalloc(len + 1, GFP_KERNEL);
+	if (!buf)
+		return ERR_PTR(-ENOMEM);
+
+	for (i = 0; i < pathname->ncomponents; i++) {
+		const struct nfs4_string *component = &pathname->components[i];
 
-	*--end = '\0';
-	buflen--;
-
-	n = pathname->ncomponents;
-	while (--n >= 0) {
-		const struct nfs4_string *component = &pathname->components[n];
-		buflen -= component->len + 1;
-		if (buflen < 0)
-			goto Elong;
-		end -= component->len;
-		memcpy(end, component->data, component->len);
-		*--end = '/';
+		*p++ = '/';
+		memcpy(p, component->data, component->len);
+		p += component->len;
 	}
-	return end;
-Elong:
-	return ERR_PTR(-ENAMETOOLONG);
+
+	*p = 0;
+	return buf;
 }
 
 /*
@@ -100,21 +128,32 @@ static char *nfs4_path(struct dentry *dentry, char *buffer, ssize_t buflen)
  */
 static int nfs4_validate_fspath(struct dentry *dentry,
 				const struct nfs4_fs_locations *locations,
-				char *page, char *page2)
+				struct nfs_fs_context *ctx)
 {
 	const char *path, *fs_path;
+	char *buf;
+	unsigned short len;
+	int n;
 
-	path = nfs4_path(dentry, page, PAGE_SIZE);
-	if (IS_ERR(path))
+	buf = kmalloc(4096, GFP_KERNEL);
+	path = nfs4_path(dentry, buf, 4096);
+	if (IS_ERR(path)) {
+		kfree(buf);
 		return PTR_ERR(path);
+	}
 
-	fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
-	if (IS_ERR(fs_path))
+	fs_path = nfs4_pathname_string(&locations->fs_path, &len);
+	if (IS_ERR(fs_path)) {
+		kfree(buf);
 		return PTR_ERR(fs_path);
+	}
 
-	if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
+	n = strncmp(path, fs_path, len);
+	kfree(buf);
+	kfree(fs_path);
+	if (n != 0) {
 		dprintk("%s: path %s does not begin with fsroot %s\n",
-			__func__, path, fs_path);
+			__func__, path, ctx->nfs_server.export_path);
 		return -ENOENT;
 	}
 
@@ -236,55 +275,83 @@ nfs4_negotiate_security(struct rpc_clnt *clnt, struct inode *inode,
 	return new;
 }
 
-static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
-				     char *page, char *page2,
-				     const struct nfs4_fs_location *location)
+static int try_location(struct fs_context *fc,
+			const struct nfs4_fs_location *location)
 {
 	const size_t addr_bufsize = sizeof(struct sockaddr_storage);
-	struct net *net = rpc_net_ns(NFS_SB(mountdata->sb)->client);
-	struct vfsmount *mnt = ERR_PTR(-ENOENT);
-	char *mnt_path;
-	unsigned int maxbuflen;
-	unsigned int s;
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
+	unsigned int len, s;
+	char *export_path, *source, *p;
+	int ret = -ENOENT;
+
+	/* Allocate a buffer big enough to hold any of the hostnames plus a
+	 * terminating char and also a buffer big enough to hold the hostname
+	 * plus a colon plus the path.
+	 */
+	len = 0;
+	for (s = 0; s < location->nservers; s++) {
+		const struct nfs4_string *buf = &location->servers[s];
+		if (buf->len > len)
+			len = buf->len;
+	}
 
-	mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
-	if (IS_ERR(mnt_path))
-		return ERR_CAST(mnt_path);
-	mountdata->mnt_path = mnt_path;
-	maxbuflen = mnt_path - 1 - page2;
+	kfree(ctx->nfs_server.hostname);
+	ctx->nfs_server.hostname = kmalloc(len + 1, GFP_KERNEL);
+	if (!ctx->nfs_server.hostname)
+		return -ENOMEM;
 
-	mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
-	if (mountdata->addr == NULL)
-		return ERR_PTR(-ENOMEM);
+	export_path = nfs4_pathname_string(&location->rootpath,
+					   &ctx->nfs_server.export_path_len);
+	if (IS_ERR(export_path))
+		return PTR_ERR(export_path);
 
+	ctx->nfs_server.export_path = export_path;
+
+	source = kmalloc(len + 1 + ctx->nfs_server.export_path_len + 1,
+			 GFP_KERNEL);
+	if (!source)
+		return -ENOMEM;
+
+	kfree(fc->source);
+	fc->source = source;
+
+	ctx->clone_data.addr = kmalloc(addr_bufsize, GFP_KERNEL);
+	if (ctx->clone_data.addr == NULL)
+		return -ENOMEM;
 	for (s = 0; s < location->nservers; s++) {
 		const struct nfs4_string *buf = &location->servers[s];
 
-		if (buf->len <= 0 || buf->len >= maxbuflen)
-			continue;
-
 		if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
 			continue;
 
-		mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
-				mountdata->addr, addr_bufsize, net);
-		if (mountdata->addrlen == 0)
+		ctx->clone_data.addrlen =
+			nfs_parse_server_name(buf->data, buf->len,
+					      ctx->clone_data.addr,
+					      addr_bufsize,
+					      fc->net_ns);
+		if (ctx->clone_data.addrlen == 0)
 			continue;
 
-		memcpy(page2, buf->data, buf->len);
-		page2[buf->len] = '\0';
-		mountdata->hostname = page2;
+		rpc_set_port(ctx->clone_data.addr, NFS_PORT);
 
-		snprintf(page, PAGE_SIZE, "%s:%s",
-				mountdata->hostname,
-				mountdata->mnt_path);
+		memcpy(ctx->nfs_server.hostname, buf->data, buf->len);
+		ctx->nfs_server.hostname[buf->len] = '\0';
+		ctx->clone_data.hostname = ctx->nfs_server.hostname;
 
-		mnt = vfs_submount(mountdata->dentry, &nfs4_referral_fs_type, page, mountdata);
-		if (!IS_ERR(mnt))
-			break;
+		p = source;
+		memcpy(p, buf->data, buf->len);
+		p += buf->len;
+		*p++ = ':';
+		memcpy(p, ctx->nfs_server.export_path, ctx->nfs_server.export_path_len);
+		p += ctx->nfs_server.export_path_len;
+		*p = 0;
+
+		ret = nfs4_get_referral_tree(fc);
+		if (ret == 0)
+			return 0;
 	}
-	kfree(mountdata->addr);
-	return mnt;
+
+	return ret;
 }
 
 /**
@@ -293,38 +360,23 @@ static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
  * @locations: array of NFSv4 server location information
  *
  */
-static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
-					    const struct nfs4_fs_locations *locations)
+static int nfs_follow_referral(struct fs_context *fc,
+			       const struct nfs4_fs_locations *locations)
 {
-	struct vfsmount *mnt = ERR_PTR(-ENOENT);
-	struct nfs_clone_mount mountdata = {
-		.sb = dentry->d_sb,
-		.dentry = dentry,
-		.authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
-	};
-	char *page = NULL, *page2 = NULL;
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
 	int loc, error;
 
 	if (locations == NULL || locations->nlocations <= 0)
-		goto out;
-
-	dprintk("%s: referral at %pd2\n", __func__, dentry);
-
-	page = (char *) __get_free_page(GFP_USER);
-	if (!page)
-		goto out;
+		return -ENOENT;
 
-	page2 = (char *) __get_free_page(GFP_USER);
-	if (!page2)
-		goto out;
+	dprintk("%s: referral at %pd2\n", __func__, ctx->clone_data.dentry);
 
 	/* Ensure fs path is a prefix of current dentry path */
-	error = nfs4_validate_fspath(dentry, locations, page, page2);
-	if (error < 0) {
-		mnt = ERR_PTR(error);
-		goto out;
-	}
+	error = nfs4_validate_fspath(ctx->clone_data.dentry, locations, ctx);
+	if (error < 0)
+		return error;
 
+	error = -ENOENT;
 	for (loc = 0; loc < locations->nlocations; loc++) {
 		const struct nfs4_fs_location *location = &locations->locations[loc];
 
@@ -332,15 +384,12 @@ static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
 		    location->rootpath.ncomponents == 0)
 			continue;
 
-		mnt = try_location(&mountdata, page, page2, location);
-		if (!IS_ERR(mnt))
-			break;
+		error = try_location(fc, location);
+		if (error == 0)
+			return 0;
 	}
 
-out:
-	free_page((unsigned long) page);
-	free_page((unsigned long) page2);
-	return mnt;
+	return error;
 }
 
 /*
@@ -348,71 +397,73 @@ static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
  * @dentry - dentry of referral
  *
  */
-static struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry)
+static int nfs_do_refmount(struct fs_context *fc, struct rpc_clnt *client)
 {
-	struct vfsmount *mnt = ERR_PTR(-ENOMEM);
-	struct dentry *parent;
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
+	struct dentry *dentry, *parent;
 	struct nfs4_fs_locations *fs_locations = NULL;
 	struct page *page;
-	int err;
+	int err = -ENOMEM;
 
 	/* BUG_ON(IS_ROOT(dentry)); */
 	page = alloc_page(GFP_KERNEL);
-	if (page == NULL)
-		return mnt;
+	if (!page)
+		return -ENOMEM;
 
 	fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
-	if (fs_locations == NULL)
+	if (!fs_locations)
 		goto out_free;
 
 	/* Get locations */
-	mnt = ERR_PTR(-ENOENT);
-
+	dentry = ctx->clone_data.dentry;
 	parent = dget_parent(dentry);
 	dprintk("%s: getting locations for %pd2\n",
 		__func__, dentry);
 
 	err = nfs4_proc_fs_locations(client, d_inode(parent), &dentry->d_name, fs_locations, page);
 	dput(parent);
-	if (err != 0 ||
-	    fs_locations->nlocations <= 0 ||
+	if (err != 0)
+		goto out_free_2;
+
+	err = -ENOENT;
+	if (fs_locations->nlocations <= 0 ||
 	    fs_locations->fs_path.ncomponents <= 0)
-		goto out_free;
+		goto out_free_2;
 
-	mnt = nfs_follow_referral(dentry, fs_locations);
+	err = nfs_follow_referral(fc, fs_locations);
+out_free_2:
+	kfree(fs_locations);
 out_free:
 	__free_page(page);
-	kfree(fs_locations);
-	return mnt;
+	return err;
 }
 
-struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry,
-			       struct nfs_fh *fh, struct nfs_fattr *fattr)
+int nfs4_submount(struct fs_context *fc, struct nfs_server *server)
 {
-	rpc_authflavor_t flavor = server->client->cl_auth->au_flavor;
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
+	struct dentry *dentry = ctx->clone_data.dentry;
 	struct dentry *parent = dget_parent(dentry);
 	struct inode *dir = d_inode(parent);
 	const struct qstr *name = &dentry->d_name;
 	struct rpc_clnt *client;
-	struct vfsmount *mnt;
+	int ret;
 
 	/* Look it up again to get its attributes and sec flavor */
-	client = nfs4_proc_lookup_mountpoint(dir, name, fh, fattr);
+	client = nfs4_proc_lookup_mountpoint(dir, name, ctx->mount_info.mntfh,
+					     ctx->clone_data.fattr);
 	dput(parent);
 	if (IS_ERR(client))
-		return ERR_CAST(client);
+		return PTR_ERR(client);
 
-	if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
-		mnt = nfs_do_refmount(client, dentry);
-		goto out;
+	ctx->selected_flavor = client->cl_auth->au_flavor;
+	if (ctx->clone_data.fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
+		ret = nfs_do_refmount(fc, client);
+	} else {
+		ret = nfs_do_submount(fc);
 	}
 
-	if (client->cl_auth->au_flavor != flavor)
-		flavor = client->cl_auth->au_flavor;
-	mnt = nfs_do_submount(dentry, fh, fattr, flavor);
-out:
 	rpc_shutdown_client(client);
-	return mnt;
+	return ret;
 }
 
 /*

fs/nfs/nfs4proc.c

@@ -10001,7 +10001,7 @@ const struct nfs_rpc_ops nfs_v4_clientops = {
 	.file_ops	= &nfs4_file_operations,
 	.getroot	= nfs4_proc_get_root,
 	.submount	= nfs4_submount,
-	.try_mount	= nfs4_try_mount,
+	.try_get_tree	= nfs4_try_get_tree,
 	.getattr	= nfs4_proc_getattr,
 	.setattr	= nfs4_proc_setattr,
 	.lookup		= nfs4_proc_lookup,

fs/nfs/nfs4super.c

@@ -4,6 +4,7 @@
  */
 #include <linux/init.h>
 #include <linux/module.h>
+#include <linux/mount.h>
 #include <linux/nfs4_mount.h>
 #include <linux/nfs_fs.h>
 #include "delegation.h"
@@ -18,16 +19,6 @@
 
 static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc);
 static void nfs4_evict_inode(struct inode *inode);
-static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
-	int flags, const char *dev_name, void *raw_data);
-
-struct file_system_type nfs4_referral_fs_type = {
-	.owner		= THIS_MODULE,
-	.name		= "nfs4",
-	.mount		= nfs4_referral_mount,
-	.kill_sb	= nfs_kill_super,
-	.fs_flags	= FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
-};
 
 static const struct super_operations nfs4_sops = {
 	.alloc_inode	= nfs_alloc_inode,
@@ -41,7 +32,6 @@ static const struct super_operations nfs4_sops = {
 	.show_devname	= nfs_show_devname,
 	.show_path	= nfs_show_path,
 	.show_stats	= nfs_show_stats,
-	.remount_fs	= nfs_remount,
 };
 
 struct nfs_subversion nfs_v4 = {
@@ -147,102 +137,121 @@ static void nfs_referral_loop_unprotect(void)
 	kfree(p);
 }
 
-static struct dentry *do_nfs4_mount(struct nfs_server *server, int flags,
-				    struct nfs_mount_info *info,
-				    const char *hostname,
-				    const char *export_path)
+static int do_nfs4_mount(struct nfs_server *server,
+			 struct fs_context *fc,
+			 const char *hostname,
+			 const char *export_path)
 {
+	struct nfs_fs_context *root_ctx;
+	struct fs_context *root_fc;
 	struct vfsmount *root_mnt;
 	struct dentry *dentry;
-	char *root_devname;
-	int err;
 	size_t len;
+	int ret;
+
+	struct fs_parameter param = {
+		.key	= "source",
+		.type	= fs_value_is_string,
+		.dirfd	= -1,
+	};
 
 	if (IS_ERR(server))
-		return ERR_CAST(server);
+		return PTR_ERR(server);
 
-	len = strlen(hostname) + 5;
-	root_devname = kmalloc(len, GFP_KERNEL);
-	if (root_devname == NULL) {
+	root_fc = vfs_dup_fs_context(fc);
+	if (IS_ERR(root_fc)) {
 		nfs_free_server(server);
-		return ERR_PTR(-ENOMEM);
+		return PTR_ERR(root_fc);
+	}
+	kfree(root_fc->source);
+	root_fc->source = NULL;
+
+	root_ctx = nfs_fc2context(root_fc);
+	root_ctx->internal = true;
+	root_ctx->mount_info.server = server;
+	/* We leave export_path unset as it's not used to find the root. */
+
+	len = strlen(hostname) + 5;
+	param.string = kmalloc(len, GFP_KERNEL);
+	if (param.string == NULL) {
+		put_fs_context(root_fc);
+		return -ENOMEM;
 	}
 
 	/* Does hostname needs to be enclosed in brackets? */
 	if (strchr(hostname, ':'))
-		snprintf(root_devname, len, "[%s]:/", hostname);
+		param.size = snprintf(param.string, len, "[%s]:/", hostname);
 	else
-		snprintf(root_devname, len, "%s:/", hostname);
-	info->server = server;
-	root_mnt = vfs_kern_mount(&nfs_prepared_fs_type, flags, root_devname, info);
-	if (info->server)
-		nfs_free_server(info->server);
-	info->server = NULL;
-	kfree(root_devname);
+		param.size = snprintf(param.string, len, "%s:/", hostname);
+	ret = vfs_parse_fs_param(root_fc, &param);
+	kfree(param.string);
+	if (ret < 0) {
+		put_fs_context(root_fc);
+		return ret;
+	}
+	root_mnt = fc_mount(root_fc);
+	put_fs_context(root_fc);
 
 	if (IS_ERR(root_mnt))
-		return ERR_CAST(root_mnt);
+		return PTR_ERR(root_mnt);
 
-	err = nfs_referral_loop_protect();
-	if (err) {
+	ret = nfs_referral_loop_protect();
+	if (ret) {
 		mntput(root_mnt);
-		return ERR_PTR(err);
+		return ret;
 	}
 
 	dentry = mount_subtree(root_mnt, export_path);
 	nfs_referral_loop_unprotect();
 
-	return dentry;
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
+
+	fc->root = dentry;
+	return 0;
 }
 
-struct dentry *nfs4_try_mount(int flags, const char *dev_name,
-			      struct nfs_mount_info *mount_info)
+int nfs4_try_get_tree(struct fs_context *fc)
 {
-	struct nfs_fs_context *ctx = mount_info->ctx;
-	struct dentry *res;
-
-	dfprintk(MOUNT, "--> nfs4_try_mount()\n");
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
+	int err;
 
-	res = do_nfs4_mount(nfs4_create_server(mount_info),
-			    flags, mount_info,
-			    ctx->nfs_server.hostname,
-			    ctx->nfs_server.export_path);
+	dfprintk(MOUNT, "--> nfs4_try_get_tree()\n");
 
-	dfprintk(MOUNT, "<-- nfs4_try_mount() = %d%s\n",
-		 PTR_ERR_OR_ZERO(res),
-		 IS_ERR(res) ? " [error]" : "");
-	return res;
+	/* We create a mount for the server's root, walk to the requested
+	 * location and then create another mount for that.
+	 */
+	err= do_nfs4_mount(nfs4_create_server(&ctx->mount_info),
+			   fc, ctx->nfs_server.hostname,
+			   ctx->nfs_server.export_path);
+	if (err) {
+		dfprintk(MOUNT, "<-- nfs4_try_get_tree() = %d [error]\n", err);
+	} else {
+		dfprintk(MOUNT, "<-- nfs4_try_get_tree() = 0\n");
+	}
+	return err;
 }
 
 /*
  * Create an NFS4 server record on referral traversal
  */
-static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
-		int flags, const char *dev_name, void *raw_data)
+int nfs4_get_referral_tree(struct fs_context *fc)
 {
-	struct nfs_clone_mount *data = raw_data;
-	struct nfs_mount_info mount_info = {
-		.cloned = data,
-		.nfs_mod = &nfs_v4,
-	};
-	struct dentry *res;
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
+	int err;
 
 	dprintk("--> nfs4_referral_mount()\n");
 
-	mount_info.mntfh = nfs_alloc_fhandle();
-	if (!mount_info.mntfh)
-		return ERR_PTR(-ENOMEM);
-
-	res = do_nfs4_mount(nfs4_create_referral_server(mount_info.cloned,
-							mount_info.mntfh),
-			    flags, &mount_info, data->hostname, data->mnt_path);
-
-	dprintk("<-- nfs4_referral_mount() = %d%s\n",
-		PTR_ERR_OR_ZERO(res),
-		IS_ERR(res) ? " [error]" : "");
-
-	nfs_free_fhandle(mount_info.mntfh);
-	return res;
+	/* create a new volume representation */
+	err = do_nfs4_mount(nfs4_create_referral_server(&ctx->clone_data, ctx->mount_info.mntfh),
+			    fc, ctx->nfs_server.hostname,
+			    ctx->nfs_server.export_path);
+	if (err) {
+		dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = %d [error]\n", err);
+	} else {
+		dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = 0\n");
+	}
+	return err;
 }
 
 

fs/nfs/proc.c

@@ -710,7 +710,7 @@ const struct nfs_rpc_ops nfs_v2_clientops = {
 	.file_ops	= &nfs_file_operations,
 	.getroot	= nfs_proc_get_root,
 	.submount	= nfs_submount,
-	.try_mount	= nfs_try_mount,
+	.try_get_tree	= nfs_try_get_tree,
 	.getattr	= nfs_proc_getattr,
 	.setattr	= nfs_proc_setattr,
 	.lookup		= nfs_proc_lookup,

fs/nfs/super.c

@@ -70,28 +70,6 @@
 
 #define NFSDBG_FACILITY		NFSDBG_VFS
 
-static struct dentry *nfs_prepared_mount(struct file_system_type *fs_type,
-		int flags, const char *dev_name, void *raw_data);
-
-struct file_system_type nfs_fs_type = {
-	.owner		= THIS_MODULE,
-	.name		= "nfs",
-	.mount		= nfs_fs_mount,
-	.kill_sb	= nfs_kill_super,
-	.fs_flags	= FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
-};
-MODULE_ALIAS_FS("nfs");
-EXPORT_SYMBOL_GPL(nfs_fs_type);
-
-struct file_system_type nfs_prepared_fs_type = {
-	.owner		= THIS_MODULE,
-	.name		= "nfs",
-	.mount		= nfs_prepared_mount,
-	.kill_sb	= nfs_kill_super,
-	.fs_flags	= FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
-};
-EXPORT_SYMBOL_GPL(nfs_prepared_fs_type);
-
 const struct super_operations nfs_sops = {
 	.alloc_inode	= nfs_alloc_inode,
 	.free_inode	= nfs_free_inode,
@@ -104,22 +82,10 @@ const struct super_operations nfs_sops = {
 	.show_devname	= nfs_show_devname,
 	.show_path	= nfs_show_path,
 	.show_stats	= nfs_show_stats,
-	.remount_fs	= nfs_remount,
 };
 EXPORT_SYMBOL_GPL(nfs_sops);
 
 #if IS_ENABLED(CONFIG_NFS_V4)
-struct file_system_type nfs4_fs_type = {
-	.owner		= THIS_MODULE,
-	.name		= "nfs4",
-	.mount		= nfs_fs_mount,
-	.kill_sb	= nfs_kill_super,
-	.fs_flags	= FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
-};
-MODULE_ALIAS_FS("nfs4");
-MODULE_ALIAS("nfs4");
-EXPORT_SYMBOL_GPL(nfs4_fs_type);
-
 static int __init register_nfs4_fs(void)
 {
 	return register_filesystem(&nfs4_fs_type);
@@ -911,20 +877,19 @@ static struct nfs_server *nfs_try_mount_request(struct nfs_mount_info *mount_inf
 	return nfs_mod->rpc_ops->create_server(mount_info);
 }
 
-static struct dentry *nfs_fs_mount_common(int, const char *, struct nfs_mount_info *);
-
-struct dentry *nfs_try_mount(int flags, const char *dev_name,
-			     struct nfs_mount_info *mount_info)
+int nfs_try_get_tree(struct fs_context *fc)
 {
-	struct nfs_subversion *nfs_mod = mount_info->nfs_mod;
-	if (mount_info->ctx->need_mount)
-		mount_info->server = nfs_try_mount_request(mount_info);
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
+
+	if (ctx->need_mount)
+		ctx->mount_info.server = nfs_try_mount_request(&ctx->mount_info);
 	else
-		mount_info->server = nfs_mod->rpc_ops->create_server(mount_info);
+		ctx->mount_info.server = ctx->mount_info.nfs_mod->rpc_ops->create_server(&ctx->mount_info);
 
-	return nfs_fs_mount_common(flags, dev_name, mount_info);
+	return nfs_get_tree_common(fc);
 }
-EXPORT_SYMBOL_GPL(nfs_try_mount);
+EXPORT_SYMBOL_GPL(nfs_try_get_tree);
+
 
 #define NFS_REMOUNT_CMP_FLAGMASK ~(NFS_MOUNT_INTR \
 		| NFS_MOUNT_SECURE \
@@ -965,15 +930,11 @@ nfs_compare_remount_data(struct nfs_server *nfss,
 	return 0;
 }
 
-int
-nfs_remount(struct super_block *sb, int *flags, char *raw_data)
+int nfs_reconfigure(struct fs_context *fc)
 {
-	int error;
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
+	struct super_block *sb = fc->root->d_sb;
 	struct nfs_server *nfss = sb->s_fs_info;
-	struct nfs_fs_context *ctx;
-	struct nfs_mount_data *options = (struct nfs_mount_data *)raw_data;
-	struct nfs4_mount_data *options4 = (struct nfs4_mount_data *)raw_data;
-	u32 nfsvers = nfss->nfs_client->rpc_ops->version;
 
 	sync_filesystem(sb);
 
@@ -983,57 +944,24 @@ nfs_remount(struct super_block *sb, int *flags, char *raw_data)
 	 * ones were explicitly specified. Fall back to legacy behavior and
 	 * just return success.
 	 */
-	if ((nfsvers == 4 && (!options4 || options4->version == 1)) ||
-	    (nfsvers <= 3 && (!options || (options->version >= 1 &&
-					   options->version <= 6))))
+	if (ctx->skip_reconfig_option_check)
 		return 0;
 
-	ctx = nfs_alloc_parsed_mount_data();
-	if (ctx == NULL)
-		return -ENOMEM;
-
-	/* fill out struct with values from existing mount */
-	ctx->flags = nfss->flags;
-	ctx->rsize = nfss->rsize;
-	ctx->wsize = nfss->wsize;
-	ctx->retrans = nfss->client->cl_timeout->to_retries;
-	ctx->selected_flavor = nfss->client->cl_auth->au_flavor;
-	ctx->acregmin = nfss->acregmin / HZ;
-	ctx->acregmax = nfss->acregmax / HZ;
-	ctx->acdirmin = nfss->acdirmin / HZ;
-	ctx->acdirmax = nfss->acdirmax / HZ;
-	ctx->timeo = 10U * nfss->client->cl_timeout->to_initval / HZ;
-	ctx->nfs_server.port = nfss->port;
-	ctx->nfs_server.addrlen = nfss->nfs_client->cl_addrlen;
-	ctx->version = nfsvers;
-	ctx->minorversion = nfss->nfs_client->cl_minorversion;
-	ctx->net = current->nsproxy->net_ns;
-	memcpy(&ctx->nfs_server.address, &nfss->nfs_client->cl_addr,
-		ctx->nfs_server.addrlen);
-
-	/* overwrite those values with any that were specified */
-	error = -EINVAL;
-	if (!nfs_parse_mount_options((char *)options, ctx))
-		goto out;
-
 	/*
 	 * noac is a special case. It implies -o sync, but that's not
-	 * necessarily reflected in the mtab options. do_remount_sb
+	 * necessarily reflected in the mtab options. reconfigure_super
 	 * will clear SB_SYNCHRONOUS if -o sync wasn't specified in the
 	 * remount options, so we have to explicitly reset it.
 	 */
-	if (ctx->flags & NFS_MOUNT_NOAC)
-		*flags |= SB_SYNCHRONOUS;
+	if (ctx->flags & NFS_MOUNT_NOAC) {
+		fc->sb_flags |= SB_SYNCHRONOUS;
+		fc->sb_flags_mask |= SB_SYNCHRONOUS;
+	}
 
 	/* compare new mount options with old ones */
-	error = nfs_compare_remount_data(nfss, ctx);
-	if (!error)
-		error = security_sb_remount(sb, ctx->lsm_opts);
-out:
-	nfs_free_parsed_mount_data(ctx);
-	return error;
+	return nfs_compare_remount_data(nfss, ctx);
 }
-EXPORT_SYMBOL_GPL(nfs_remount);
+EXPORT_SYMBOL_GPL(nfs_reconfigure);
 
 /*
  * Finish setting up an NFS superblock
@@ -1112,19 +1040,11 @@ static int nfs_compare_mount_options(const struct super_block *s, const struct n
 	return 0;
 }
 
-struct nfs_sb_mountdata {
-	struct nfs_server *server;
-	int mntflags;
-};
-
-static int nfs_set_super(struct super_block *s, void *data)
+static int nfs_set_super(struct super_block *s, struct fs_context *fc)
 {
-	struct nfs_sb_mountdata *sb_mntdata = data;
-	struct nfs_server *server = sb_mntdata->server;
+	struct nfs_server *server = fc->s_fs_info;
 	int ret;
 
-	s->s_flags = sb_mntdata->mntflags;
-	s->s_fs_info = server;
 	s->s_d_op = server->nfs_client->rpc_ops->dentry_ops;
 	ret = set_anon_super(s, server);
 	if (ret == 0)
@@ -1189,11 +1109,9 @@ static int nfs_compare_userns(const struct nfs_server *old,
 	return 1;
 }
 
-static int nfs_compare_super(struct super_block *sb, void *data)
+static int nfs_compare_super(struct super_block *sb, struct fs_context *fc)
 {
-	struct nfs_sb_mountdata *sb_mntdata = data;
-	struct nfs_server *server = sb_mntdata->server, *old = NFS_SB(sb);
-	int mntflags = sb_mntdata->mntflags;
+	struct nfs_server *server = fc->s_fs_info, *old = NFS_SB(sb);
 
 	if (!nfs_compare_super_address(old, server))
 		return 0;
@@ -1204,13 +1122,12 @@ static int nfs_compare_super(struct super_block *sb, void *data)
 		return 0;
 	if (!nfs_compare_userns(old, server))
 		return 0;
-	return nfs_compare_mount_options(sb, server, mntflags);
+	return nfs_compare_mount_options(sb, server, fc->sb_flags);
 }
 
 #ifdef CONFIG_NFS_FSCACHE
 static void nfs_get_cache_cookie(struct super_block *sb,
-				 struct nfs_fs_context *ctx,
-				 struct nfs_clone_mount *cloned)
+				 struct nfs_fs_context *ctx)
 {
 	struct nfs_server *nfss = NFS_SB(sb);
 	char *uniq = NULL;
@@ -1219,30 +1136,32 @@ static void nfs_get_cache_cookie(struct super_block *sb,
 	nfss->fscache_key = NULL;
 	nfss->fscache = NULL;
 
-	if (ctx) {
-		if (!(ctx->options & NFS_OPTION_FSCACHE))
-			return;
-		if (ctx->fscache_uniq) {
-			uniq = ctx->fscache_uniq;
-			ulen = strlen(ctx->fscache_uniq);
-		}
-	} else if (cloned) {
-		struct nfs_server *mnt_s = NFS_SB(cloned->sb);
+	if (!ctx)
+		return;
+
+	if (ctx->clone_data.sb) {
+		struct nfs_server *mnt_s = NFS_SB(ctx->clone_data.sb);
 		if (!(mnt_s->options & NFS_OPTION_FSCACHE))
 			return;
 		if (mnt_s->fscache_key) {
 			uniq = mnt_s->fscache_key->key.uniquifier;
 			ulen = mnt_s->fscache_key->key.uniq_len;
 		}
-	} else
+	} else {
+		if (!(ctx->options & NFS_OPTION_FSCACHE))
+			return;
+		if (ctx->fscache_uniq) {
+			uniq = ctx->fscache_uniq;
+			ulen = strlen(ctx->fscache_uniq);
+		}
 		return;
+	}
 
 	nfs_fscache_get_super_cookie(sb, uniq, ulen);
 }
 #else
 static void nfs_get_cache_cookie(struct super_block *sb,
-				 struct nfs_fs_context *parsed,
-				 struct nfs_clone_mount *cloned)
+				 struct nfs_fs_context *ctx)
 {
 }
 #endif
@@ -1254,40 +1173,41 @@ static void nfs_set_readahead(struct backing_dev_info *bdi,
 	bdi->io_pages = iomax_pages;
 }
 
-static struct dentry *nfs_fs_mount_common(int flags, const char *dev_name,
-				   struct nfs_mount_info *mount_info)
+int nfs_get_tree_common(struct fs_context *fc)
 {
+	struct nfs_fs_context *ctx = nfs_fc2context(fc);
 	struct super_block *s;
 	struct dentry *mntroot = ERR_PTR(-ENOMEM);
-	int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
-	struct nfs_server *server = mount_info->server;
+	int (*compare_super)(struct super_block *, struct fs_context *) = nfs_compare_super;
+	struct nfs_server *server = ctx->mount_info.server;
 	unsigned long kflags = 0, kflags_out = 0;
-	struct nfs_sb_mountdata sb_mntdata = {
-		.mntflags = flags,
-		.server = server,
-	};
 	int error;
 
-	mount_info->server = NULL;
+	ctx->mount_info.server = NULL;
 	if (IS_ERR(server))
-		return ERR_CAST(server);
+		return PTR_ERR(server);
 
 	if (server->flags & NFS_MOUNT_UNSHARED)
 		compare_super = NULL;
 
 	/* -o noac implies -o sync */
 	if (server->flags & NFS_MOUNT_NOAC)
-		sb_mntdata.mntflags |= SB_SYNCHRONOUS;
+		fc->sb_flags |= SB_SYNCHRONOUS;
+
+	if (ctx->clone_data.sb)
+		if (ctx->clone_data.sb->s_flags & SB_SYNCHRONOUS)
+			fc->sb_flags |= SB_SYNCHRONOUS;
 
-	if (mount_info->cloned != NULL && mount_info->cloned->sb != NULL)
-		if (mount_info->cloned->sb->s_flags & SB_SYNCHRONOUS)
-			sb_mntdata.mntflags |= SB_SYNCHRONOUS;
+	if (server->caps & NFS_CAP_SECURITY_LABEL)
+		fc->lsm_flags |= SECURITY_LSM_NATIVE_LABELS;
 
 	/* Get a superblock - note that we may end up sharing one that already exists */
-	s = sget(mount_info->nfs_mod->nfs_fs, compare_super, nfs_set_super,
-		 flags, &sb_mntdata);
+	fc->s_fs_info = server;
+	s = sget_fc(fc, compare_super, nfs_set_super);
+	fc->s_fs_info = NULL;
 	if (IS_ERR(s)) {
-		mntroot = ERR_CAST(s);
+		error = PTR_ERR(s);
+		dfprintk(MOUNT, "NFS: Couldn't get superblock\n");
 		goto out_err_nosb;
 	}
 
@@ -1297,44 +1217,43 @@ static struct dentry *nfs_fs_mount_common(int flags, const char *dev_name,
 	} else {
 		error = super_setup_bdi_name(s, "%u:%u", MAJOR(server->s_dev),
 					     MINOR(server->s_dev));
-		if (error) {
-			mntroot = ERR_PTR(error);
+		if (error)
 			goto error_splat_super;
-		}
 		nfs_set_readahead(s->s_bdi, server->rpages);
 		server->super = s;
 	}
 
 	if (!s->s_root) {
-		unsigned bsize = mount_info->inherited_bsize;
+		unsigned bsize = ctx->mount_info.inherited_bsize;
 		/* initial superblock/root creation */
-		nfs_fill_super(s, mount_info);
+		nfs_fill_super(s, &ctx->mount_info);
 		if (bsize) {
 			s->s_blocksize_bits = bsize;
 			s->s_blocksize = 1U << bsize;
 		}
-		nfs_get_cache_cookie(s, mount_info->ctx, mount_info->cloned);
-		if (!(server->flags & NFS_MOUNT_UNSHARED))
-			s->s_iflags |= SB_I_MULTIROOT;
+		nfs_get_cache_cookie(s, ctx);
 	}
 
-	mntroot = nfs_get_root(s, mount_info->mntfh, dev_name);
-	if (IS_ERR(mntroot))
+	mntroot = nfs_get_root(s, ctx->mount_info.mntfh, fc->source);
+	if (IS_ERR(mntroot)) {
+		error = PTR_ERR(mntroot);
+		dfprintk(MOUNT, "NFS: Couldn't get root dentry\n");
 		goto error_splat_super;
-
+	}
+	fc->root = mntroot;
 
 	if (NFS_SB(s)->caps & NFS_CAP_SECURITY_LABEL)
 		kflags |= SECURITY_LSM_NATIVE_LABELS;
-	if (mount_info->cloned) {
-		if (d_inode(mntroot)->i_fop != &nfs_dir_operations) {
+	if (ctx->clone_data.sb) {
+		if (d_inode(fc->root)->i_fop != &nfs_dir_operations) {
 			error = -ESTALE;
 			goto error_splat_root;
 		}
 		/* clone any lsm security options from the parent to the new sb */
-		error = security_sb_clone_mnt_opts(mount_info->cloned->sb, s, kflags,
+		error = security_sb_clone_mnt_opts(ctx->clone_data.sb, s, kflags,
 				&kflags_out);
 	} else {
-		error = security_sb_set_mnt_opts(s, mount_info->ctx->lsm_opts,
+		error = security_sb_set_mnt_opts(s, fc->security,
 							kflags, &kflags_out);
 	}
 	if (error)
@@ -1342,67 +1261,25 @@ static struct dentry *nfs_fs_mount_common(int flags, const char *dev_name,
 	if (NFS_SB(s)->caps & NFS_CAP_SECURITY_LABEL &&
 		!(kflags_out & SECURITY_LSM_NATIVE_LABELS))
 		NFS_SB(s)->caps &= ~NFS_CAP_SECURITY_LABEL;
-	if (error)
-		goto error_splat_root;
 
 	s->s_flags |= SB_ACTIVE;
+	error = 0;
 
 out:
-	return mntroot;
+	return error;
 
 out_err_nosb:
 	nfs_free_server(server);
 	goto out;
 
 error_splat_root:
-	dput(mntroot);
-	mntroot = ERR_PTR(error);
+	dput(fc->root);
+	fc->root = NULL;
 error_splat_super:
 	deactivate_locked_super(s);
 	goto out;
 }
 
-struct dentry *nfs_fs_mount(struct file_system_type *fs_type,
-	int flags, const char *dev_name, void *raw_data)
-{
-	struct nfs_mount_info mount_info = {
-	};
-	struct dentry *mntroot = ERR_PTR(-ENOMEM);
-	struct nfs_subversion *nfs_mod;
-	int error;
-
-	mount_info.ctx = nfs_alloc_parsed_mount_data();
-	mount_info.mntfh = nfs_alloc_fhandle();
-	if (mount_info.ctx == NULL || mount_info.mntfh == NULL)
-		goto out;
-
-	/* Validate the mount data */
-	error = nfs_validate_mount_data(fs_type, raw_data, mount_info.ctx, mount_info.mntfh, dev_name);
-	if (error == NFS_TEXT_DATA)
-		error = nfs_validate_text_mount_data(raw_data,
-						     mount_info.ctx, dev_name);
-	if (error < 0) {
-		mntroot = ERR_PTR(error);
-		goto out;
-	}
-
-	nfs_mod = get_nfs_version(mount_info.ctx->version);
-	if (IS_ERR(nfs_mod)) {
-		mntroot = ERR_CAST(nfs_mod);
-		goto out;
-	}
-	mount_info.nfs_mod = nfs_mod;
-
-	mntroot = nfs_mod->rpc_ops->try_mount(flags, dev_name, &mount_info);
-
-	put_nfs_version(nfs_mod);
-out:
-	nfs_free_parsed_mount_data(mount_info.ctx);
-	nfs_free_fhandle(mount_info.mntfh);
-	return mntroot;
-}
-EXPORT_SYMBOL_GPL(nfs_fs_mount);
-
 /*
  * Destroy an NFS2/3 superblock
  */
@@ -1420,17 +1297,6 @@ void nfs_kill_super(struct super_block *s)
 }
 EXPORT_SYMBOL_GPL(nfs_kill_super);
 
-/*
- * Internal use only: mount_info is already set up by caller.
- * Used for mountpoint crossings and for nfs4 root.
- */
-static struct dentry *
-nfs_prepared_mount(struct file_system_type *fs_type, int flags,
-		   const char *dev_name, void *raw_data)
-{
-	return nfs_fs_mount_common(flags, dev_name, raw_data);
-}
-
 #if IS_ENABLED(CONFIG_NFS_V4)
 
 /*

include/linux/nfs_xdr.h

@@ -1639,6 +1639,7 @@ struct nfs_subversion;
 struct nfs_mount_info;
 struct nfs_client_initdata;
 struct nfs_pageio_descriptor;
+struct fs_context;
 
 /*
  * RPC procedure vector for NFSv2/NFSv3 demuxing
@@ -1653,9 +1654,8 @@ struct nfs_rpc_ops {
 
 	int	(*getroot) (struct nfs_server *, struct nfs_fh *,
 			    struct nfs_fsinfo *);
-	struct vfsmount *(*submount) (struct nfs_server *, struct dentry *,
-				      struct nfs_fh *, struct nfs_fattr *);
-	struct dentry *(*try_mount) (int, const char *, struct nfs_mount_info *);
+	int	(*submount) (struct fs_context *, struct nfs_server *);
+	int	(*try_get_tree) (struct fs_context *);
 	int	(*getattr) (struct nfs_server *, struct nfs_fh *,
 			    struct nfs_fattr *, struct nfs4_label *,
 			    struct inode *);