linux-kernel - Re: [PATCH] block: correctly fallback for zeroout

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>] [day] [month] [year] [list]

Date:	Thu, 02 Jun 2016 22:56:05 -0400
From:	"Martin K. Petersen" <martin.petersen@...cle.com>
To:	Sitsofe Wheeler <sitsofe@...oo.com>
Cc:	Shaohua Li <shli@...com>, linux-block@...r.kernel.org,
	linux-kernel@...r.kernel.org, snitzer@...hat.com, axboe@...com,
	martin.petersen@...cle.com, Kernel-team@...com
Subject: Re: [PATCH] block: correctly fallback for zeroout

>>>>> "Sitsofe" == Sitsofe Wheeler <sitsofe@...oo.com> writes:

Sitsofe> The original SCSI WRITE SAME has overloaded semantics - not
Sitsofe> only does it mean "write this data multiple times" but it can
Sitsofe> also be used to mean "discard this range" too. If the kernel's
Sitsofe> command was modelled on the SCSI original perhaps this
Sitsofe> conflation clouded things?

REQ_WRITE_SAME in the context of the kernel explicitly means "write
payload to this block range".

A REQ_DISCARD command may be serviced using WRITE SAME(16) with the
UNMAP bit set in the SCSI disk driver but that's entirely orthogonal.

-- 
Martin K. Petersen	Oracle Linux Engineering