From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cantor2.suse.de ([195.135.220.15]:44639 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752157AbbGUITL (ORCPT ); Tue, 21 Jul 2015 04:19:11 -0400 Message-ID: <55AE007C.9030807@suse.de> Date: Tue, 21 Jul 2015 10:19:08 +0200 From: Hannes Reinecke MIME-Version: 1.0 To: device-mapper development , Jens Axboe CC: "Martin K. Petersen" , linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, Liu Bo , linux-btrfs@vger.kernel.org Subject: Re: [dm-devel] [PATCH] block: add a bi_error field to struct bio References: <1437398977-8492-1-git-send-email-hch@lst.de> <1437398977-8492-2-git-send-email-hch@lst.de> In-Reply-To: <1437398977-8492-2-git-send-email-hch@lst.de> Content-Type: text/plain; charset=windows-1252 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 07/20/2015 03:29 PM, Christoph Hellwig wrote: > Currently we have two different ways to signal an I/O error on a BIO: > > (1) by clearing the BIO_UPTODATE flag > (2) by returning a Linux errno value to the bi_end_io callback > > The first one has the drawback of only communicating a single possible > error (-EIO), and the second one has the drawback of not beeing persistent > when bios are queued up, and are not passed along from child to parent > bio in the ever more popular chaining scenario. Having both mechanisms > available has the additional drawback of utterly confusing driver authors > and introducing bugs where various I/O submitters only deal with one of > them, and the others have to add boilerplate code to deal with both kinds > of error returns. > > So add a new bi_error field to store an errno value directly in struct > bio and remove the existing mechanisms to clean all this up. > > Signed-off-by: Christoph Hellwig > --- Very good improvement. Reviewed-by: Hannes Reinecke Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)