Add support for filesystem labels via mkfs.btrfs -L

ctree.h

@@ -235,6 +235,7 @@ struct btrfs_header {
  * room to translate 14 chunks with 3 stripes each.
  */
 #define BTRFS_SYSTEM_CHUNK_ARRAY_SIZE 2048
+#define BTRFS_LABEL_SIZE 256
 
 /*
  * the super block basically lists the main trees of the FS
@@ -264,6 +265,7 @@ struct btrfs_super_block {
 	u8 root_level;
 	u8 chunk_root_level;
 	struct btrfs_dev_item dev_item;
+	char label[BTRFS_LABEL_SIZE];
 	u8 sys_chunk_array[BTRFS_SYSTEM_CHUNK_ARRAY_SIZE];
 } __attribute__ ((__packed__));
 

mkfs.c

@@ -260,12 +260,32 @@ static u64 parse_profile(char *s)
 	return 0;
 }
 
+static char *parse_label(char *input)
+{
+	int i;
+	int len = strlen(input);
+
+	if (len > BTRFS_LABEL_SIZE) {
+		fprintf(stderr, "Label %s is too long (max %d)\n", input,
+			BTRFS_LABEL_SIZE);
+		exit(1);
+	}
+	for (i = 0; i < len; i++) {
+		if (input[i] == '/' || input[i] == '\\') {
+			fprintf(stderr, "invalid label %s\n", input);
+			exit(1);
+		}
+	}
+	return strdup(input);
+}
+
 static struct option long_options[] = {
 	{ "byte-count", 1, NULL, 'b' },
 	{ "leafsize", 1, NULL, 'l' },
+	{ "label", 1, NULL, 'L'},
+	{ "metadata", 1, NULL, 'm' },
 	{ "nodesize", 1, NULL, 'n' },
 	{ "sectorsize", 1, NULL, 's' },
-	{ "metadata", 1, NULL, 'm' },
 	{ "data", 1, NULL, 'd' },
 	{ 0, 0, 0, 0}
 };
@@ -273,27 +293,28 @@ static struct option long_options[] = {
 int main(int ac, char **av)
 {
 	char *file;
+	struct btrfs_root *root;
+	struct btrfs_trans_handle *trans;
+	char *label = NULL;
 	u64 block_count = 0;
 	u64 dev_block_count = 0;
-	int fd;
+	u64 blocks[6];
-	int first_fd;
+	u64 metadata_profile = BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_DUP;
-	int ret;
+	u64 data_profile = BTRFS_BLOCK_GROUP_RAID0;
-	int i;
 	u32 leafsize = getpagesize();
 	u32 sectorsize = 4096;
 	u32 nodesize = leafsize;
 	u32 stripesize = 4096;
-	u64 blocks[6];
 	int zero_end = 1;
 	int option_index = 0;
-	struct btrfs_root *root;
+	int fd;
-	struct btrfs_trans_handle *trans;
+	int first_fd;
-	u64 metadata_profile = BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_DUP;
+	int ret;
-	u64 data_profile = BTRFS_BLOCK_GROUP_RAID0;
+	int i;
 
 	while(1) {
 		int c;
-		c = getopt_long(ac, av, "b:l:n:s:m:d:", long_options,
+		c = getopt_long(ac, av, "b:l:n:s:m:d:L:", long_options,
 				&option_index);
 		if (c < 0)
 			break;
@@ -301,12 +322,15 @@ int main(int ac, char **av)
 			case 'd':
 				data_profile = parse_profile(optarg);
 				break;
-			case 'm':
-				metadata_profile = parse_profile(optarg);
 				break;
 			case 'l':
 				leafsize = parse_size(optarg);
 				break;
+			case 'L':
+				label = parse_label(optarg);
+				break;
+			case 'm':
+				metadata_profile = parse_profile(optarg);
 			case 'n':
 				nodesize = parse_size(optarg);
 				break;
@@ -358,7 +382,8 @@ int main(int ac, char **av)
 	for (i = 0; i < 6; i++)
 		blocks[i] = BTRFS_SUPER_INFO_OFFSET + leafsize * i;
 
-	ret = make_btrfs(fd, file, blocks, block_count, nodesize, leafsize,
+	ret = make_btrfs(fd, file, label, blocks, block_count,
+			 nodesize, leafsize,
 			 sectorsize, stripesize);
 	if (ret) {
 		fprintf(stderr, "error during mkfs %d\n", ret);
@@ -369,10 +394,12 @@ int main(int ac, char **av)
 		fprintf(stderr, "failed to setup the root directory\n");
 		exit(1);
 	}
-	printf("fs created on %s nodesize %u leafsize %u sectorsize %u bytes %llu\n",
+	printf("fs created label %s on %s\n\tnodesize %u leafsize %u "
-	       file, nodesize, leafsize, sectorsize,
+	       "sectorsize %u bytes %llu\n",
+	       label, file, nodesize, leafsize, sectorsize,
 	       (unsigned long long)block_count);
 
+	free(label);
 	root = open_ctree(file, 0);
 	trans = btrfs_start_transaction(root, 1);
 
@@ -403,13 +430,12 @@ int main(int ac, char **av)
 			fprintf(stderr, "unable to open %s\n", file);
 			exit(1);
 		}
-		fprintf(stderr, "adding device %s\n", file);
 		ret = btrfs_prepare_device(fd, file, zero_end,
 					   &dev_block_count);
 
 		BUG_ON(ret);
 
-		ret = btrfs_add_to_fsid(trans, root, fd, dev_block_count,
+		ret = btrfs_add_to_fsid(trans, root, fd, file, dev_block_count,
 					sectorsize, sectorsize, sectorsize);
 		BUG_ON(ret);
 		btrfs_register_one_device(file);

utils.c

@@ -54,7 +54,7 @@ static u64 reference_root_table[6] = {
 	[5] =	BTRFS_FS_TREE_OBJECTID,
 };
 
-int make_btrfs(int fd, char *device_name,
+int make_btrfs(int fd, char *device_name, char *label,
 	       u64 blocks[6], u64 num_bytes, u32 nodesize,
 	       u32 leafsize, u32 sectorsize, u32 stripesize)
 {
@@ -84,10 +84,11 @@ int make_btrfs(int fd, char *device_name,
 	first_free = BTRFS_SUPER_INFO_OFFSET + sectorsize * 2 - 1;
 	first_free &= ~((u64)sectorsize - 1);
 
+	memset(&super, 0, sizeof(super));
+
 	num_bytes = (num_bytes / sectorsize) * sectorsize;
 	uuid_generate(super.fsid);
 	uuid_generate(super.dev_item.uuid);
-
 	uuid_generate(chunk_tree_uuid);
 
 	btrfs_set_super_bytenr(&super, blocks[0]);
@@ -98,14 +99,12 @@ int make_btrfs(int fd, char *device_name,
 	btrfs_set_super_chunk_root(&super, blocks[3]);
 	btrfs_set_super_total_bytes(&super, num_bytes);
 	btrfs_set_super_bytes_used(&super, first_free + 5 * leafsize);
-	btrfs_set_super_root_dir(&super, 0);
 	btrfs_set_super_sectorsize(&super, sectorsize);
 	btrfs_set_super_leafsize(&super, leafsize);
 	btrfs_set_super_nodesize(&super, nodesize);
 	btrfs_set_super_stripesize(&super, stripesize);
-	btrfs_set_super_root_level(&super, 0);
+	if (label)
-	btrfs_set_super_chunk_root_level(&super, 0);
+		strcpy(super.label, label);
-	btrfs_set_super_sys_array_size(&super, 0);
 
 	buf = malloc(sizeof(*buf) + max(sectorsize, leafsize));
 
@@ -429,8 +428,9 @@ static int zero_dev_end(int fd, u64 dev_size)
 }
 
 int btrfs_add_to_fsid(struct btrfs_trans_handle *trans,
-		      struct btrfs_root *root, int fd, u64 block_count,
+		      struct btrfs_root *root, int fd, char *path,
-		      u32 io_width, u32 io_align, u32 sectorsize)
+		      u64 block_count, u32 io_width, u32 io_align,
+		      u32 sectorsize)
 {
 	struct btrfs_super_block *disk_super;
 	struct btrfs_super_block *super = &root->fs_info->super_copy;
@@ -478,7 +478,9 @@ int btrfs_add_to_fsid(struct btrfs_trans_handle *trans,
 
 	memcpy(disk_super, super, sizeof(*disk_super));
 
-	printf("adding device id %llu\n", (unsigned long long)device->devid);
+	printf("adding device %s id %llu\n", path,
+	       (unsigned long long)device->devid);
+
 	btrfs_set_stack_device_id(dev_item, device->devid);
 	btrfs_set_stack_device_type(dev_item, device->type);
 	btrfs_set_stack_device_io_align(dev_item, device->io_align);

utils.h

@@ -21,7 +21,7 @@
 
 #define BTRFS_MKFS_SYSTEM_GROUP_SIZE (4 * 1024 * 1024)
 
-int make_btrfs(int fd, char *device_name,
+int make_btrfs(int fd, char *device_name, char *label,
 	       u64 blocks[6], u64 num_bytes, u32 nodesize,
 	       u32 leafsize, u32 sectorsize, u32 stripesize);
 int btrfs_make_root_dir(struct btrfs_trans_handle *trans,
@@ -29,8 +29,9 @@ int btrfs_make_root_dir(struct btrfs_trans_handle *trans,
 int btrfs_prepare_device(int fd, char *file, int zero_end,
 			 u64 *block_count_ret);
 int btrfs_add_to_fsid(struct btrfs_trans_handle *trans,
-		      struct btrfs_root *root, int fd, u64 block_count,
+		      struct btrfs_root *root, int fd, char *path,
-		      u32 io_width, u32 io_align, u32 sectorsize);
+		      u64 block_count, u32 io_width, u32 io_align,
+		      u32 sectorsize);
 int btrfs_scan_for_fsid(struct btrfs_fs_devices *fs_devices, u64 total_devs,
 			int run_ioctls);
 int btrfs_register_one_device(char *fname);

volumes.c

@@ -128,7 +128,6 @@ static int device_list_add(const char *path,
 	}
 	if (fs_devices->lowest_devid > devid) {
 		fs_devices->lowest_devid = devid;
-		printk("lowest devid now %llu\n", (unsigned long long)devid);
 	}
 	*fs_devices_ret = fs_devices;
 	return 0;
@@ -184,6 +183,7 @@ int btrfs_scan_one_device(int fd, const char *path,
 	char *buf;
 	int ret;
 	u64 devid;
+	char uuidbuf[37];
 
 	buf = malloc(4096);
 	if (!buf) {
@@ -203,7 +203,14 @@ int btrfs_scan_one_device(int fd, const char *path,
 	}
 	devid = le64_to_cpu(disk_super->dev_item.devid);
 	*total_devs = btrfs_super_num_devices(disk_super);
-	printk("found device %llu on %s\n", (unsigned long long)devid, path);
+	uuid_unparse(disk_super->fsid, uuidbuf);
+
+	printf("device ");
+	if (disk_super->label[0])
+		printf("label %s ", disk_super->label);
+	else
+		printf("fsuuid %s ", uuidbuf);
+	printf("devid %llu %s\n", (unsigned long long)devid, path);
 	ret = device_list_add(path, disk_super, devid, fs_devices_ret);
 
 error_brelse: