Re: [PATCH V2] mkfs.btrfs: allow UUID specification at mkfs time

[Eric Sandeen <sandeen@redhat.com>]

On 5/14/14, 11:01 AM, David Sterba wrote:
> Thanks for adding the uuid uniqueness check, that was my major
> objection for previous patch iterations,
> 
> http://www.spinics.net/lists/linux-btrfs/msg30572.html

Ah, thanks, I didn't know about that history, I'm sorry.

I'm not sure if my duplicate-check is over the top, you had suggested

	blkid_probe_lookup_value()

before, maybe that's simpler.  I'm not a blkid expert... but it seems to work.

> we can now use it for convert as well (to generate or copy the uuid).

woo ;)

-Eric

> On Wed, May 14, 2014 at 10:35:05AM -0500, Eric Sandeen wrote:
>> @@ -125,7 +154,19 @@ 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;
> 
> I think the uuid validity check comes too late, IMHO it should be done
> after the while/getopt block outside of make_btrfs. At this point eg.
> the discard or device zeroing is already done.
> 
> I would not mind to keep the check here as well as a last sanity check,
> though the number of mkfs_btrfs callers is 1 and the function is not
> exported to the library.
> 
>> +		}
>> +		if (!test_uuid_unique(fs_uuid)) {
>> +			fprintf(stderr, "non-unique UUID: %s\n", fs_uuid);
>> +			ret = -EBUSY;
>> +			goto out;
>> +		}
>> +	} else
>> +		uuid_generate(super.fsid);
>>  	uuid_generate(super.dev_item.uuid);
>>  	uuid_generate(chunk_tree_uuid);