From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753481Ab1GNDUq (ORCPT ); Wed, 13 Jul 2011 23:20:46 -0400 Received: from mail-iy0-f174.google.com ([209.85.210.174]:44278 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753295Ab1GNDUo (ORCPT ); Wed, 13 Jul 2011 23:20:44 -0400 Message-ID: <4E1E6052.6030002@vflare.org> Date: Wed, 13 Jul 2011 20:19:46 -0700 From: Nitin Gupta User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:5.0) Gecko/20110624 Thunderbird/5.0 MIME-Version: 1.0 To: Jerome Marchand CC: Greg Kroah-Hartman , Linux Kernel List , Robert Jennings , Jeff Moyer Subject: Re: [PATCH 3/4] Staging: zram: allow partial page operations References: <1307712529-9757-1-git-send-email-jmarchan@redhat.com> <1307712529-9757-2-git-send-email-jmarchan@redhat.com> <1307712529-9757-3-git-send-email-jmarchan@redhat.com> <4DF2493F.8040507@vflare.org> <4E0D97C5.5040005@redhat.com> In-Reply-To: <4E0D97C5.5040005@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/01/2011 02:47 AM, Jerome Marchand wrote: > On 06/10/2011 06:41 PM, Nitin Gupta wrote: >> On 06/10/2011 06:28 AM, Jerome Marchand wrote: >>> Commit 7b19b8d45b216ff3186f066b31937bdbde066f08 (zram: Prevent overflow >>> in logical block size) introduced ZRAM_LOGICAL_BLOCK_SIZE constant to >>> prevent overflow of logical block size on 64k page kernel. >>> However, the current implementation of zram only allow operation on block >>> of the same size as a page. That makes theorically legit 4k requests fail >>> on 64k page kernel. >>> >>> This patch makes zram allow operation on partial pages. Basically, it >>> means we still do operations on full pages internally, but only copy the >>> relevent segments from/to the user memory. >>> >> >> Couldn't we just change struct queue_limits.logical_block_size type to >> unsigned int or something so it could hold value of 64K? Then we could >> avoid making all these changes to handle partial page requests. > > I've finally done some tests. At least FAT filesystems are unable to cope > with 64k logical blocks. Probably some other fs are affected too. I we want > to support them, zram need to handle operation on partial pages. > Sorry for late reply. If this is the case, we surely need partial page operations. I also looked into these patches and they look good (though I've have not tested them). Thanks, Nitin