linux-kernel - Re: [PATCH] UBIFS: fill f

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 01 Sep 2008 14:16:50 +0300
From:	Artem Bityutskiy <dedekind@...radead.org>
To:	David Woodhouse <dwmw2@...radead.org>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	Adrian Hunter <ext-adrian.hunter@...ia.com>
Subject: Re: [PATCH] UBIFS: fill f_fsid

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.

-- 
Best regards,
Artem Bityutskiy (Битюцкий Артём)

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/