From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martin K. Petersen" Subject: Re: Wrong DIF guard tag on ext2 write Date: Thu, 03 Jun 2010 21:46:02 -0400 Message-ID: References: <20100601162929.GC32708@parisc-linux.org> <20100601164750.GQ8980@think> <1275411293.21962.387.camel@mulgrave.site> <20100601180905.GR8980@think> <20100601184649.GE9453@laptop> <20100601193528.GV8980@think> <20100602032030.GF9453@laptop> <20100602134121.GD6152@laptop> <20100603154634.GC8980@think> <20100603162718.GR6822@laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Chris Mason , "Martin K. Petersen" , James Bottomley , Matthew Wilcox , Christof Schmitt , Boaz Harrosh , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org To: Nick Piggin Return-path: In-Reply-To: <20100603162718.GR6822@laptop> (Nick Piggin's message of "Fri, 4 Jun 2010 02:27:18 +1000") Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org >>>>> "Nick" == Nick Piggin writes: Nick> Also I don't think we can deal with memory errors and scribbles Nick> just by crcing dirty data. The calculations generating the data Nick> could get corrupted. Yep, the goal is to make the window as small as possible. Nick> Data can be corrupted on its way back from the device to Nick> userspace. We also get a CRC back from the storage. So the (integrity-aware) application is also able to check on read. Nick> Obviously this feature is being pushed by databases and such that Nick> really want to pass checksums all the way from userspace. Block Nick> retrying is _not_ needed or wanted here of course. Nope. The integrity error is bubbled all the way up to the database and we can decide to retry, recreate or error out depending on what we find when we do validation checks on the data buffer and the integrity metadata. -- Martin K. Petersen Oracle Linux Engineering