linux-ext4 - Re: [PATCH, RFC] mke2fs: get device topology values from blkid

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]

Message-ID: <yq1ab0s6ny7.fsf@sermon.lab.mkp.net>
Date:	Fri, 18 Sep 2009 15:40:48 -0400
From:	"Martin K. Petersen" <martin.petersen@...cle.com>
To:	Eric Sandeen <sandeen@...hat.com>
Cc:	"Martin K. Petersen" <martin.petersen@...cle.com>,
	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH, RFC] mke2fs: get device topology values from blkid

>>>>> "Eric" == Eric Sandeen <sandeen@...hat.com> writes:

>> Also, are you guys affected by the
>> previously-acked-sectors-are-now-gone problems with 512-byte
>> logical/4KB physical drives?

Eric> previously-acked-sectors-are-now-gone?  I guess I haven't been
Eric> keeping up.  What do you mean by this?

We already discussed this on irc.  But in case anybody else are
wondering...

On a disk with 4KB physical blocks emulating 512-byte logical blocks the
drive firmware must resort to read-modify-write cycles and that opens up
a new error scenario:

4KB physical block: |                       0                       |
512b logical block: |  0  |  1  |  2  |  3  |  4  |  5  |  6  |  7  |
                                                                 ^ ERROR

In this case we have successfully written LBA 0 - 6.  However, when the
drive attempts to write LBA 7 it gets an I/O error and the previous 7
logical blocks (that have previously been acknowledged as written) are
lost.  IOW, the drive write atomicity is at the physical block level and
not the logical ditto.

See http://oss.oracle.com/~mkp/docs/ls09-topology.pdf page 19 for
prettier graphics.

-- 
Martin K. Petersen	Oracle Linux Engineering
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html