linux-kernel - Re: UBI fastmap updates

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:	Thu, 02 Aug 2012 19:45:30 +0300
From:	Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>
To:	Richard Weinberger <richard@....at>
Cc:	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
	adrian.hunter@...el.com, Heinz.Egger@...utronix.de,
	thomas.wucher@...utronix.de, shmulik.ladkani@...il.com,
	tglx@...utronix.de, tim.bird@...sony.com, Marius.Mazarel@...l.ro,
	nyoushchenko@...sta.com
Subject: Re: UBI fastmap updates

Richard,

On Thu, 2012-08-02 at 18:32 +0200, Richard Weinberger wrote:
> > This should not happen. Fastmap should _reserve_ enough of PEBs for it
> > to operate. It should always find the PEB to write.
> 
> What is the benefit?
> IOW what is wrong with the current approach?

Several reasons. The main is: fastmap will start consuming PEBs reserved
for volumes when the amount of available PEBs is just enough to map all
LEBs. This will break UBI liability.

> Why?
> If everything goes wrong, fastmap makes sure that no fastmap is on
> flash.
> In case of a powercut we fall back to scanning mode.
> R/O mode is overkill IMHO.

So can I interpret this the following way. Not only fastmap give no
guarantees that it exists after an unclean reboot, it does not even give
guarantees that it exists after a clean reboot.

Unless I am confused, the fastmap design is over-simplified.


-- 
Best Regards,
Artem Bityutskiy

Download attachment "signature.asc" of type "application/pgp-signature" (837 bytes)