Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753520AbZIRPw0 (ORCPT ); Fri, 18 Sep 2009 11:52:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752965AbZIRPwZ (ORCPT ); Fri, 18 Sep 2009 11:52:25 -0400 Received: from mx1.redhat.com ([209.132.183.28]:65108 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751585AbZIRPwZ (ORCPT ); Fri, 18 Sep 2009 11:52:25 -0400 Date: Fri, 18 Sep 2009 11:52:17 -0400 From: Mike Snitzer To: "Jun'ichi Nomura" Cc: Jens Axboe , Alasdair G Kergon , "Martin K. Petersen" , David Strand , device-mapper development , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] dm: Set safe default max_sectors for targets with no underlying device Message-ID: <20090918155217.GA28926@redhat.com> References: <4AB3A4CC.4010708@ce.jp.nec.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4AB3A4CC.4010708@ce.jp.nec.com> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2633 Lines: 68 On Fri, Sep 18 2009 at 11:18am -0400, Jun'ichi Nomura wrote: > This is a preparation for the next patch, which changes > blk_set_default_limits() to set 0 for max_sectors/max_hw_sectors. > With the next patch, for dm targets like 'zero', where there's no > underlying device, those values remain 0 and the dm device becomes > unusable. > > So check the max_sectors and set to SAFE_MAX_SECTORS if 0. > > Check this thread for further background: > https://www.redhat.com/archives/dm-devel/2009-September/msg00176.html > > > Signed-off-by: Kiyoshi Ueda > Signed-off-by: Jun'ichi Nomura > Cc: David Strand > Cc: Mike Snitzer > Cc: Alasdair G Kergon > Cc: Martin K. Petersen > Cc: Jens Axboe > --- > drivers/md/dm-table.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > Index: linux-2.6.31.work/drivers/md/dm-table.c > =================================================================== > --- linux-2.6.31.work.orig/drivers/md/dm-table.c > +++ linux-2.6.31.work/drivers/md/dm-table.c > @@ -707,6 +707,17 @@ static int validate_hardware_logical_blo > device_logical_block_size_sects - next_target_start : 0; > } > > + /* > + * blk_set_default_limits() sets max_sectors/max_hw_sectors to 0. > + * When all targets have no underlying device, they are > + * left unchanged from the default values and cause problems. > + * Use SAFE_MAX_SECTORS for such cases. > + */ > + if (limits->max_hw_sectors == 0) > + limits->max_hw_sectors = SAFE_MAX_SECTORS; > + if (limits->max_sectors == 0) > + limits->max_sectors = SAFE_MAX_SECTORS; > + > if (remaining) { > DMWARN("%s: table line %u (start sect %llu len %llu) " > "not aligned to h/w logical block size %u", The blk_set_default_limits() that matters, as referenced in your comment block, is actually in dm_calculate_queue_limits(). It would be better to put these checks in dm_calculate_queue_limits() just before the call to validate_hardware_logical_block_alignment(). Either way works because the checks are effectively at the end of dm_calculate_queue_limits() -- which is where they need to be. But I think you're polluting validate_hardware_logical_block_alignment() with unrelated checks. Thanks, Mike -- 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/