linux-kernel - Re: [RFC] Heads up on sys

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 for Android: free password hash cracker in your pocket

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

Message-ID: <20070305114945.GB454@lazybastard.org>
Date:	Mon, 5 Mar 2007 12:49:45 +0100
From:	Jörn Engel <joern@...ybastard.org>
To:	Anton Altaparmakov <aia21@....ac.uk>
Cc:	Ulrich Drepper <drepper@...hat.com>, Arnd Bergmann <arnd@...db.de>,
	Christoph Hellwig <hch@...radead.org>,
	Dave Kleikamp <shaggy@...ux.vnet.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Amit K. Arora" <aarora@...ux.vnet.ibm.com>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-ext4@...r.kernel.org, suparna@...ibm.com, cmm@...ibm.com,
	alex@...sterfs.com, suzuki@...ibm.com
Subject: Re: [RFC] Heads up on sys_fallocate()

On Mon, 5 March 2007 00:32:14 +0000, Anton Altaparmakov wrote:
> 
> I don't know how your compression algorithm works [...]

LogFS is designed for flash media, so it does not have to worry much
about reducing disk seeks.  It is log-structured, which simplifies
compression further.

When writing a block, it basically compresses it and appends it to the
log.  Writes only have to be byte-aligned, so no space is lost for
padding.

The bad news for posix_fallocate() is that even if libc is smart enough
to write random data, mmap() can still cause problems.  If the VM
decides to write a given page twice, the second write compresses better
and the medium has filled up between the two writes, the users will have
fun.

Jörn

-- 
Joern's library part 9:
http://www.scl.ameslab.gov/Publications/Gus/TwelveWays.html
-
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/