ext4: add test for ext4 uuid get/set ioctls during fsstress.

Adds a utility to get/set uuid through ext4 ioctl. Executes the ioctls
while running fsstress. These ioctls are used by tune2fs to safely change
the uuid without racing other filesystem modifications.

Reviewed-by: Zorro Lang <zlang@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Jeremy Bongio <bongiojp@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Zorro Lang <zlang@kernel.org>

2 files changed, 108 insertions, 2 deletions

diff --git a/src/Makefile b/src/Makefile
index 7eeb08ef..665edcf9 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -31,14 +31,15 @@ LINUX_TARGETS = xfsctl bstat t_mtab getdevicesize preallo_rw_pattern_reader \
 	dio-invalidate-cache stat_test t_encrypted_d_revalidate \
 	attr_replace_test swapon mkswap t_attr_corruption t_open_tmpfiles \
 	fscrypt-crypt-util bulkstat_null_ocount splice-test chprojid_fail \
-	detached_mounts_propagation ext4_resize t_readdir_3 splice2pipe
+	detached_mounts_propagation ext4_resize t_readdir_3 splice2pipe \
+	uuid_ioctl
 
 EXTRA_EXECS = dmerror fill2attr fill2fs fill2fs_check scaleread.sh \
 	      btrfs_crc32c_forged_name.py
 
 SUBDIRS = log-writes perf
 
-LLDLIBS = $(LIBHANDLE) $(LIBACL) -lpthread -lrt
+LLDLIBS = $(LIBHANDLE) $(LIBACL) -lpthread -lrt -luuid
 
 ifeq ($(HAVE_XLOG_ASSIGN_LSN), true)
 LINUX_TARGETS += loggen
diff --git a/src/uuid_ioctl.c b/src/uuid_ioctl.c
new file mode 100644
index 00000000..89a9b5d8
--- /dev/null
+++ b/src/uuid_ioctl.c
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2022 Google, Inc. All Rights Reserved.
+ *
+ * Test program which uses the raw ext4 set_fsuuid ioctl directly.
+ * SYNOPSIS:
+ *   $0 COMMAND MOUNT_POINT [UUID]
+ *
+ * COMMAND must be either "get" or "set".
+ * The UUID must be a 16 octet sequence represented as 32 hexadecimal digits in
+ * canonical textual representation, e.g. output from `uuidgen`.
+ *
+ */
+
+#include <stdio.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <uuid/uuid.h>
+#include <linux/fs.h>
+
+struct fsuuid {
+	__u32   fsu_len;
+	__u32   fsu_flags;
+	__u8    fsu_uuid[];
+};
+
+#ifndef EXT4_IOC_GETFSUUID
+#define EXT4_IOC_GETFSUUID      _IOR('f', 44, struct fsuuid)
+#endif
+
+#ifndef EXT4_IOC_SETFSUUID
+#define EXT4_IOC_SETFSUUID      _IOW('f', 44, struct fsuuid)
+#endif
+
+int main(int argc, char **argv)
+{
+	int error, fd;
+	struct fsuuid *fsuuid = NULL;
+
+	if (argc < 3) {
+		fprintf(stderr, "Invalid arguments\n");
+		return 1;
+	}
+
+	fd = open(argv[2], O_RDONLY);
+	if (!fd) {
+		perror(argv[2]);
+		return 1;
+	}
+
+	fsuuid = malloc(sizeof(*fsuuid) + sizeof(uuid_t));
+	if (!fsuuid) {
+		perror("malloc");
+		return 1;
+	}
+	fsuuid->fsu_len = sizeof(uuid_t);
+	fsuuid->fsu_flags = 0;
+
+	if (strcmp(argv[1], "get") == 0) {
+		uuid_t uuid;
+		char uuid_str[37];
+
+		if (ioctl(fd, EXT4_IOC_GETFSUUID, fsuuid)) {
+			fprintf(stderr, "%s while trying to get fs uuid\n",
+				strerror(errno));
+			return 1;
+		}
+
+		memcpy(&uuid, fsuuid->fsu_uuid, sizeof(uuid));
+		uuid_unparse(uuid, uuid_str);
+		printf("%s\n", uuid_str);
+	} else if (strcmp(argv[1], "set") == 0) {
+		uuid_t uuid;
+
+		if (argc != 4) {
+			fprintf(stderr, "UUID argument missing.\n");
+			return 1;
+		}
+
+		error = uuid_parse(argv[3], uuid);
+		if (error < 0) {
+			fprintf(stderr, "Invalid UUID. The UUID should be in "
+				"canonical format. Example: "
+				"8c628557-6987-42b2-ba16-b7cc79ddfb43\n");
+			return 1;
+		}
+
+		memcpy(&fsuuid->fsu_uuid, uuid, sizeof(uuid));
+		if (ioctl(fd, EXT4_IOC_SETFSUUID, fsuuid)) {
+			fprintf(stderr, "%s while trying to set fs uuid\n",
+				strerror(errno));
+			return 1;
+		}
+	} else {
+		fprintf(stderr, "Invalid command\n");
+		return 1;
+	}
+
+	return 0;
+}