From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2F720C43441 for ; Wed, 28 Nov 2018 07:45:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E08142086B for ; Wed, 28 Nov 2018 07:45:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ukQhE4B+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E08142086B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727703AbeK1Sq2 (ORCPT ); Wed, 28 Nov 2018 13:46:28 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:47382 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727247AbeK1Sq1 (ORCPT ); Wed, 28 Nov 2018 13:46:27 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=EPIzflvAJUlGi6iavBRobzBf1shUiab75r8qH4BYRX8=; b=ukQhE4B+N5Ks7zVLHUscRckOr /AhGXkPOAwO+/aCQzRfD9WvYfJIWKOuoyCCJ6kLCj6OEk647uMZEG1Ig1IPn8zx5ckdMYG4kyekbG nhaLQYmwUadip1jYB2nA16VlXHurQ5niw0biRftJ8kCrHA8mig2CHhD7qQEcoKtD5+AwHUBOQc5JD /xm47XvnkgjCOHYFPszuwAknT7rt5WmRY5WrlMc/yDrMFNnfOho+za2mB90qcs3z9NaRZY6Slvr7S TaBFXHs++KVo1sPrSYksfh0w9XGt7mQcD85V7lhfYYFk0QVsa/Tx3Ub2UThehbPDacJ48JrQQcf8T VBKbWxn4w==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1gRuXY-00071p-RX; Wed, 28 Nov 2018 07:45:44 +0000 Date: Tue, 27 Nov 2018 23:45:44 -0800 From: Christoph Hellwig To: Dave Chinner Cc: Allison Henderson , linux-block@vger.kernel.org, linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, martin.petersen@oracle.com, shirley.ma@oracle.com, bob.liu@oracle.com Subject: Re: [RFC PATCH v1 0/7] Block/XFS: Support alternative mirror device retry Message-ID: <20181128074544.GA20702@infradead.org> References: <1543376991-5764-1-git-send-email-allison.henderson@oracle.com> <20181128053303.GL6311@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181128053303.GL6311@dastard> User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 28, 2018 at 04:33:03PM +1100, Dave Chinner wrote: > - how does propagation through stacked layers work? The only way it works is by each layering driving it. Thus my recommendation above bilding on your earlier one to use an index that is filled by the driver at I/O completion time. E.g. bio_init: bi_leg = -1 raid1: submit bio to lower driver raid 1 completion: set bi_leg to 0 or 1 Now if we want to allow stacking we need to save/restore bi_leg before submitting to the underlying device. Which is possible, but quite a bit of work in the drivers. > - is it generic/abstract enough to be able to work with > RAID5/6 to trigger verification/recovery from the parity > information in the stripe? If we get the non -1 bi_leg for paritity raid this is an inidicator that parity rebuild needs to happen. For multi-parity setups we could also use different levels there.