From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Lord Subject: Re: [PATCH 1/4] block: Allow devices to indicate whether discarded blocks are zeroed Date: Sat, 21 Nov 2009 21:43:15 -0500 Message-ID: <4B08A543.909@rtr.ca> References: <1258771524-26673-1-git-send-email-martin.petersen@oracle.com> <1258771524-26673-2-git-send-email-martin.petersen@oracle.com> <20091121101356.GA21716@infradead.org> <20091121195802.GC8502@parisc-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from rtr.ca ([76.10.145.34]:50112 "EHLO mail.rtr.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751174AbZKVCnM (ORCPT ); Sat, 21 Nov 2009 21:43:12 -0500 In-Reply-To: <20091121195802.GC8502@parisc-linux.org> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Matthew Wilcox Cc: Christoph Hellwig , "Martin K. Petersen" , jens.axboe@oracle.com, james.bottomley@hansenpartnership.com, willy@wil.cx, jgarzik@pobox.com, sandeen@redhat.com, rwheeler@redhat.com, linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org Matthew Wilcox wrote: > On Sat, Nov 21, 2009 at 05:13:56AM -0500, Christoph Hellwig wrote: >> On Fri, Nov 20, 2009 at 09:45:21PM -0500, Martin K. Petersen wrote: >>> The discard ioctl is used by mkfs utilities to clear a block device >>> prior to putting metadata down. However, not all devices return zeroed >>> blocks after a discard. Some drives return stale data, potentially >>> containing old superblocks. It is therefore important to know whether >>> discarded blocks are properly zeroed. >> At least for mkfs.xfs we make sure to still zero the important areas >> after the TRIM ioctl anyway. > > Could you change that to zero _before_ the TRIM? .. Hopefully not for the drives that *don't* guarantee zeros after TRIM. Eg. most existing ones, including all of the Indilinx chipset drives. Cheers