Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755881AbbHGHpA (ORCPT ); Fri, 7 Aug 2015 03:45:00 -0400 Received: from mail-io0-f175.google.com ([209.85.223.175]:33315 "EHLO mail-io0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755200AbbHGHo6 (ORCPT ); Fri, 7 Aug 2015 03:44:58 -0400 MIME-Version: 1.0 In-Reply-To: <20150807073330.GB17618@lst.de> References: <1437118027-94602-1-git-send-email-hare@suse.de> <20150807073330.GB17618@lst.de> Date: Fri, 7 Aug 2015 03:44:58 -0400 Message-ID: Subject: Re: [PATCH 0/4] loop: enable different physical blocksizes From: Ming Lei To: Christoph Hellwig Cc: Hannes Reinecke , Jens Axboe , Alexander Graf , Linux Kernel Mailing List Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1549 Lines: 32 On Fri, Aug 7, 2015 at 3:33 AM, Christoph Hellwig wrote: > On Mon, Jul 27, 2015 at 06:40:57AM -0400, Ming Lei wrote: >> On Fri, Jul 17, 2015 at 3:27 AM, Hannes Reinecke wrote: >> > Currently the loop driver just simulates 512-byte blocks. When >> > creating images for virtual machines it might be required to use >> > a different physical blocksize (eg 4k for S/390 DASD). >> >> Looks 'qemu-img create' doesn't have parameter of block size, >> so could you share your use case? And I am just curious why >> 512-byte can't work for this case. > > The use case is to suppot 4k sectors sizes such as DASDs usually provide, > or just to create a 4k block device to check your filesystem of choice > handles 4k sectors just fine. Replace 4k with other sector sizes of > your choice for added benefit. In addition to the DASD use case it's really a > very useful debugging tool. There shouldn't be any problem about looping over DASP which has 4k sector size. Also for debugging purpose, we can easily emulate 4k sector size disk by QEMU/virtio-blk. We can support 4k sector size on loop for debugging purpose too, but the side effect is that some images can't be loop mounted any more after its secror size is become larger, then people might complain that. Thanks, Ming Lei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/