Re: [PATCH] mkfs.btrfs: allow UUID specification at mkfs time

[Wang Shilong <wangsl.fnst@cn.fujitsu.com>]

On 05/14/2014 09:18 AM, Eric Sandeen wrote:
> Allow the specification of the filesystem UUID at mkfs time.
>
> (Implemented only for mkfs.btrfs, not btrfs-convert).
Just out of curiosity, this option is used for what kind of use case?
I notice Ext4 also has this option.:-)

>
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> ---
>
> diff --git a/btrfs-convert.c b/btrfs-convert.c
> index a8b2c51..d62d4f8 100644
> --- a/btrfs-convert.c
> +++ b/btrfs-convert.c
> @@ -2240,7 +2240,7 @@ static int do_convert(const char *devname, int datacsum, int packing,
>   		goto fail;
>   	}
>   	ret = make_btrfs(fd, devname, ext2_fs->super->s_volume_name,
> -			 blocks, total_bytes, blocksize, blocksize,
> +			 NULL, blocks, total_bytes, blocksize, blocksize,
>   			 blocksize, blocksize, 0);
>   	if (ret) {
>   		fprintf(stderr, "unable to create initial ctree: %s\n",
> diff --git a/man/mkfs.btrfs.8.in b/man/mkfs.btrfs.8.in
> index bef509d..4450d03 100644
> --- a/man/mkfs.btrfs.8.in
> +++ b/man/mkfs.btrfs.8.in
> @@ -16,6 +16,7 @@ mkfs.btrfs \- create a btrfs filesystem
>   [ \fB\-r\fP\fI rootdir\fP ]
>   [ \fB\-K\fP ]
>   [ \fB\-O\fP\fI feature1,feature2,...\fP ]
> +[ \fB\-U\fP\fI uuid\fP ]
>   [ \fB\-h\fP ]
>   [ \fB\-V\fP ]
>   \fI device\fP [ \fIdevice ...\fP ]
> @@ -90,6 +91,9 @@ To see all run
>   
>   \fBmkfs.btrfs -O list-all\fR
>   .TP
> +\fB\-U\fR, \fB\-\-uuid \fR
> +Create the filesystem with the specified UUID.
> +.TP
>   \fB\-V\fR, \fB\-\-version\fR
>   Print the \fBmkfs.btrfs\fP version and exit.
>   .SH UNIT
> diff --git a/mkfs.c b/mkfs.c
> index dbd83f5..eccb08f 100644
> --- a/mkfs.c
> +++ b/mkfs.c
> @@ -288,6 +288,7 @@ static void print_usage(void)
>   	fprintf(stderr, "\t -r --rootdir the source directory\n");
>   	fprintf(stderr, "\t -K --nodiscard do not perform whole device TRIM\n");
>   	fprintf(stderr, "\t -O --features comma separated list of filesystem features\n");
> +	fprintf(stderr, "\t -U --uuid specify the filesystem UUID\n");
>   	fprintf(stderr, "\t -V --version print the mkfs.btrfs version and exit\n");
>   	fprintf(stderr, "%s\n", BTRFS_BUILD_VERSION);
>   	exit(1);
> @@ -351,6 +352,7 @@ static struct option long_options[] = {
>   	{ "rootdir", 1, NULL, 'r' },
>   	{ "nodiscard", 0, NULL, 'K' },
>   	{ "features", 0, NULL, 'O' },
> +	{ "uuid", 0, NULL, 'U' },
>   	{ NULL, 0, NULL, 0}
>   };
>   
> @@ -1273,11 +1275,12 @@ int main(int ac, char **av)
>   	int dev_cnt = 0;
>   	int saved_optind;
>   	char estr[100];
> +	char *fs_uuid = NULL;
>   	u64 features = DEFAULT_MKFS_FEATURES;
>   
>   	while(1) {
>   		int c;
> -		c = getopt_long(ac, av, "A:b:fl:n:s:m:d:L:O:r:VMK",
> +		c = getopt_long(ac, av, "A:b:fl:n:s:m:d:L:O:r:U:VMK",
>   				long_options, &option_index);
>   		if (c < 0)
>   			break;
> @@ -1346,6 +1349,9 @@ int main(int ac, char **av)
>   				source_dir = optarg;
>   				source_dir_set = 1;
>   				break;
> +			case 'U':
> +				fs_uuid = optarg;
> +				break;
>   			case 'K':
>   				discard = 0;
>   				break;
> @@ -1514,7 +1520,7 @@ int main(int ac, char **av)
>   
>   	process_fs_features(features);
>   
> -	ret = make_btrfs(fd, file, label, blocks, dev_block_count,
> +	ret = make_btrfs(fd, file, label, fs_uuid, blocks, dev_block_count,
>   			 nodesize, leafsize,
>   			 sectorsize, stripesize, features);
>   	if (ret) {
> diff --git a/utils.c b/utils.c
> index 3e9c527..3f46e8f 100644
> --- a/utils.c
> +++ b/utils.c
> @@ -93,12 +93,12 @@ static u64 reference_root_table[] = {
>   	[6] =	BTRFS_CSUM_TREE_OBJECTID,
>   };
>   
> -int make_btrfs(int fd, const char *device, const char *label,
> +int make_btrfs(int fd, const char *device, const char *label, char *fs_uuid,
>   	       u64 blocks[7], u64 num_bytes, u32 nodesize,
>   	       u32 leafsize, u32 sectorsize, u32 stripesize, u64 features)
>   {
>   	struct btrfs_super_block super;
> -	struct extent_buffer *buf;
> +	struct extent_buffer *buf = NULL;
>   	struct btrfs_root_item root_item;
>   	struct btrfs_disk_key disk_key;
>   	struct btrfs_extent_item *extent_item;
> @@ -125,7 +125,14 @@ int make_btrfs(int fd, const char *device, const char *label,
>   	memset(&super, 0, sizeof(super));
>   
>   	num_bytes = (num_bytes / sectorsize) * sectorsize;
> -	uuid_generate(super.fsid);
> +	if (fs_uuid) {
> +		if (uuid_parse(fs_uuid, super.fsid) != 0) {
> +			fprintf(stderr, "could not parse UUID: %s\n", fs_uuid);
> +			ret = -EINVAL;
> +			goto out;
> +		}
> +	} else
> +		uuid_generate(super.fsid);
>   	uuid_generate(super.dev_item.uuid);
>   	uuid_generate(chunk_tree_uuid);
>   
> diff --git a/utils.h b/utils.h
> index 3c62066..054cbb6 100644
> --- a/utils.h
> +++ b/utils.h
> @@ -40,7 +40,7 @@
>   #define BTRFS_UUID_UNPARSED_SIZE	37
>   
>   int make_btrfs(int fd, const char *device, const char *label,
> -	       u64 blocks[6], u64 num_bytes, u32 nodesize,
> +	       char *fs_uuid, u64 blocks[6], u64 num_bytes, u32 nodesize,
>   	       u32 leafsize, u32 sectorsize, u32 stripesize, u64 features);
>   int btrfs_make_root_dir(struct btrfs_trans_handle *trans,
>   			struct btrfs_root *root, u64 objectid);
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> .
>