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 21:30:06 -0400 Message-ID: References: <1275399637.21962.11.camel@mulgrave.site> <20100601134951.GM8980@think> <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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "Martin K. Petersen" , Chris Mason , 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: <20100602134121.GD6152@laptop> (Nick Piggin's message of "Wed, 2 Jun 2010 23:41:21 +1000") Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org >>>>> "Nick" == Nick Piggin writes: Nick, >> Filesystems will inevitably have to be integrity-aware for that to >> work. And it will be their job to keep the data pages stable during >> DMA. Nick> Closing the while it is dirty, while it is being written back Nick> window still leaves a pretty big window. Also, how do you handle Nick> mmap writes? Write protect and checksum the destination page Nick> after every store? Or leave some window between when the pagecache Nick> is dirtied and when it is written back? So I don't know whether Nick> it's worth putting a lot of effort into this case. I'm mostly interested in the cases where the filesystem acts as a conduit for integrity metadata from user space. I agree the corruption windows inside the kernel are only of moderate interest. No filesystems have added support for explicitly protecting a bio because the block layer's function to do so automatically is just a few function calls away. -- Martin K. Petersen Oracle Linux Engineering