NFS: Fix the setting of capabilities when automounting a new filesystem

Capabilities cannot be inherited when we cross into a new filesystem.
They need to be reset to the minimal defaults, and then probed for
again.

Fixes: 54ceac4 ("NFS: Share NFS superblocks per-protocol per-server per-FSID")
Cc: [email protected]
Reviewed-by: Benjamin Coddington <[email protected]>
Signed-off-by: Trond Myklebust <[email protected]>

Author: Trond Myklebust

fs/nfs/client.c

@@ -682,6 +682,44 @@ struct nfs_client *nfs_init_client(struct nfs_client *clp,
 }
 EXPORT_SYMBOL_GPL(nfs_init_client);
 
+static void nfs4_server_set_init_caps(struct nfs_server *server)
+{
+#if IS_ENABLED(CONFIG_NFS_V4)
+	/* Set the basic capabilities */
+	server->caps = server->nfs_client->cl_mvops->init_caps;
+	if (server->flags & NFS_MOUNT_NORDIRPLUS)
+		server->caps &= ~NFS_CAP_READDIRPLUS;
+	if (server->nfs_client->cl_proto == XPRT_TRANSPORT_RDMA)
+		server->caps &= ~NFS_CAP_READ_PLUS;
+
+	/*
+	 * Don't use NFS uid/gid mapping if we're using AUTH_SYS or lower
+	 * authentication.
+	 */
+	if (nfs4_disable_idmapping &&
+	    server->client->cl_auth->au_flavor == RPC_AUTH_UNIX)
+		server->caps |= NFS_CAP_UIDGID_NOMAP;
+#endif
+}
+
+void nfs_server_set_init_caps(struct nfs_server *server)
+{
+	switch (server->nfs_client->rpc_ops->version) {
+	case 2:
+		server->caps = NFS_CAP_HARDLINKS | NFS_CAP_SYMLINKS;
+		break;
+	case 3:
+		server->caps = NFS_CAP_HARDLINKS | NFS_CAP_SYMLINKS;
+		if (!(server->flags & NFS_MOUNT_NORDIRPLUS))
+			server->caps |= NFS_CAP_READDIRPLUS;
+		break;
+	default:
+		nfs4_server_set_init_caps(server);
+		break;
+	}
+}
+EXPORT_SYMBOL_GPL(nfs_server_set_init_caps);
+
 /*
  * Create a version 2 or 3 client
  */
@@ -726,7 +764,6 @@ static int nfs_init_server(struct nfs_server *server,
 	/* Initialise the client representation from the mount data */
 	server->flags = ctx->flags;
 	server->options = ctx->options;
-	server->caps |= NFS_CAP_HARDLINKS | NFS_CAP_SYMLINKS;
 
 	switch (clp->rpc_ops->version) {
 	case 2:
@@ -762,6 +799,8 @@ static int nfs_init_server(struct nfs_server *server,
 	if (error < 0)
 		goto error;
 
+	nfs_server_set_init_caps(server);
+
 	/* Preserve the values of mount_server-related mount options */
 	if (ctx->mount_server.addrlen) {
 		memcpy(&server->mountd_address, &ctx->mount_server.address,
@@ -934,7 +973,6 @@ void nfs_server_copy_userdata(struct nfs_server *target, struct nfs_server *sour
 	target->acregmax = source->acregmax;
 	target->acdirmin = source->acdirmin;
 	target->acdirmax = source->acdirmax;
-	target->caps = source->caps;
 	target->options = source->options;
 	target->auth_info = source->auth_info;
 	target->port = source->port;
@@ -1169,6 +1207,8 @@ struct nfs_server *nfs_clone_server(struct nfs_server *source,
 	if (error < 0)
 		goto out_free_server;
 
+	nfs_server_set_init_caps(server);
+
 	/* probe the filesystem info for this server filesystem */
 	error = nfs_probe_server(server, fh);
 	if (error < 0)

fs/nfs/internal.h

@@ -231,7 +231,7 @@ extern struct nfs_client *
 nfs4_find_client_sessionid(struct net *, const struct sockaddr *,
 				struct nfs4_sessionid *, u32);
 extern struct nfs_server *nfs_create_server(struct fs_context *);
-extern void nfs4_server_set_init_caps(struct nfs_server *);
+extern void nfs_server_set_init_caps(struct nfs_server *);
 extern struct nfs_server *nfs4_create_server(struct fs_context *);
 extern struct nfs_server *nfs4_create_referral_server(struct fs_context *);
 extern int nfs4_update_server(struct nfs_server *server, const char *hostname,

fs/nfs/nfs4client.c

@@ -1074,24 +1074,6 @@ static void nfs4_session_limit_xasize(struct nfs_server *server)
 #endif
 }
 
-void nfs4_server_set_init_caps(struct nfs_server *server)
-{
-	/* Set the basic capabilities */
-	server->caps |= server->nfs_client->cl_mvops->init_caps;
-	if (server->flags & NFS_MOUNT_NORDIRPLUS)
-			server->caps &= ~NFS_CAP_READDIRPLUS;
-	if (server->nfs_client->cl_proto == XPRT_TRANSPORT_RDMA)
-		server->caps &= ~NFS_CAP_READ_PLUS;
-
-	/*
-	 * Don't use NFS uid/gid mapping if we're using AUTH_SYS or lower
-	 * authentication.
-	 */
-	if (nfs4_disable_idmapping &&
-			server->client->cl_auth->au_flavor == RPC_AUTH_UNIX)
-		server->caps |= NFS_CAP_UIDGID_NOMAP;
-}
-
 static int nfs4_server_common_setup(struct nfs_server *server,
 		struct nfs_fh *mntfh, bool auth_probe)
 {
@@ -1110,7 +1092,7 @@ static int nfs4_server_common_setup(struct nfs_server *server,
 	if (error < 0)
 		return error;
 
-	nfs4_server_set_init_caps(server);
+	nfs_server_set_init_caps(server);
 
 	/* Probe the root fh to retrieve its FSID and filehandle */
 	error = nfs4_get_rootfh(server, mntfh, auth_probe);

fs/nfs/nfs4proc.c

@@ -4092,7 +4092,7 @@ int nfs4_server_capabilities(struct nfs_server *server, struct nfs_fh *fhandle)
 	};
 	int err;
 
-	nfs4_server_set_init_caps(server);
+	nfs_server_set_init_caps(server);
 	do {
 		err = nfs4_handle_exception(server,
 				_nfs4_server_capabilities(server, fhandle),