On 05/14/2014 07:39 PM, Eric Sandeen wrote:
> Allow the specification of the filesystem UUID at mkfs time.
>
> Non-unique unique IDs are rejected. This includes attempting
> to re-mkfs with the same UUID; if you really want to do that,
> you can mkfs with a new UUID, then re-mkfs with the one you
> wanted. ;)
>
> (Implemented only for mkfs.btrfs, not btrfs-convert).
>
> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> ---
>
> NB: the prior patch didn't work well if you re-mkfs'd with
> the same UUID; to be honest I didn't get to the bottom of it,
> but the fact that that old UUID was already in an internal
> list of present devices seems to have confused things.
>
> V2: reject non-unique unique IDs.
> V3: test for non-unique unique IDs early in mkfs.
>
> 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, which must not already exist on the system.
> +.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..d67a5ba 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;
> @@ -1368,6 +1374,20 @@ int main(int ac, char **av)
> "The -r option is limited to a single device\n");
> exit(1);
> }
> +
> + if (fs_uuid) {
> + uuid_t dummy_uuid;
> +
> + if (uuid_parse(fs_uuid, dummy_uuid) != 0) {
> + fprintf(stderr, "could not parse UUID: %s\n", fs_uuid);
> + exit(1);
> + }
> + if (!test_uuid_unique(fs_uuid)) {
> + fprintf(stderr, "non-unique UUID: %s\n", fs_uuid);
> + exit(1);
> + }
My test showed that this detect a false positive when the user tries to mkfs two time on the same device with the same uuid.
> + }
> +
> while (dev_cnt-- > 0) {
> file = av[optind++];
> if (is_block_device(file))
> @@ -1514,7 +1534,7 @@ 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..cfac0d4 100644
> --- a/utils.c
> +++ b/utils.c
> @@ -93,12 +93,41 @@ static u64 reference_root_table[] = {
> [6] = BTRFS_CSUM_TREE_OBJECTID,
> };
>
> -int make_btrfs(int fd, const char *device, const char *label,
> +int test_uuid_unique(char *fs_uuid)
> +{
> + int unique = 1;
> + blkid_dev_iterate iter = NULL;
> + blkid_dev dev = NULL;
> + blkid_cache cache = NULL;
> +
> + if (blkid_get_cache(&cache, 0) < 0) {
> + printf("ERROR: lblkid cache get failed\n");
> + return 1;
> + }
> + blkid_probe_all(cache);
> + iter = blkid_dev_iterate_begin(cache);
> + blkid_dev_set_search(iter, "UUID", fs_uuid);
> +
> + while (blkid_dev_next(iter, &dev) == 0) {
This function should skip the check for the devices involved in the mkfs.
> + dev = blkid_verify(cache, dev);
> + if (dev) {
> + unique = 0;
> + break;
> + }
> + }
> +
> + blkid_dev_iterate_end(iter);
> + blkid_put_cache(cache);
> +
> + return unique;
> +}
> +
> +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 +154,20 @@ 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;
> + }
> + if (!test_uuid_unique(fs_uuid)) {
> + fprintf(stderr, "non-unique UUID: %s\n", fs_uuid);
> + ret = -EBUSY;
> + goto out;
> + }
Why a second call to test_uuid_unique(fs_uuid) ?
> + } 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..4a404ae 100644
> --- a/utils.h
> +++ b/utils.h
> @@ -39,8 +39,9 @@
>
> #define BTRFS_UUID_UNPARSED_SIZE 37
>
> +int test_uuid_unique(char *fs_uuid);
> 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);
>
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