On Mon, 2008-09-01 at 14:16 +0300, Artem Bityutskiy wrote: > On Mon, 2008-09-01 at 10:43 +0100, David Woodhouse wrote: > > > UBIFS stores 16-bit UUID in the superblock, and it is a good > > > idea to return part of it in 'f_fsid' filed of kstatfs structure. > > > > I think you mean a 16-byte UUID, not 16-bit? > > Oh, right. > > > > > > + memcpy(&buf->f_fsid, c->uuid, sizeof(__kernel_fsid_t)); > > > > For btrfs I xor the first 64 bits with the second 64 bits, and put > > _that_ into f_fsid. You're just putting the first 64 bits in and > > ignoring the second 64 bits. Neither is really _better_ than the other; > > you just alter the circumstances in which you get collisions. But I > > suppose we might as well be consistent about how we do it? > > Well, xor-ing should not make the random UUID more random, but for > consistency purposes sure, I may use xor as well. > > > Alternatively, there's space in the struct statfs to export a couple > > more uint32_ts, and thus the _whole_ of the uuid. Perhaps we should do > > that? > > You mean f_spare? I do not think any application would use it so I doubt > it is good idea to use it. Well, it wouldn't be called f_spare any more, and applications would know that it contains the rest of the UUID if it's non-zero. I'd fix nfsd to fix it immediately (like as I just fixed nfsd to use the first 64 bits of f_fsid when it's non-zero). -- David Woodhouse Open Source Technology Centre David.Woodhouse@xxxxxxxxx Intel Corporation -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
