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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED572C433F5 for ; Wed, 13 Apr 2022 01:57:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229945AbiDMB7a (ORCPT ); Tue, 12 Apr 2022 21:59:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57554 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229826AbiDMB73 (ORCPT ); Tue, 12 Apr 2022 21:59:29 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 81D2B19C3D for ; Tue, 12 Apr 2022 18:57:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1649815029; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Qbm1txEKKlVaSmPNDnFXUVHfbYBf6SguxzwN2wpoygs=; b=hosRl3yIzBM4j4GQgCvWBLVi3DtFXhr64e8etBvRtenCotgrh1nGdrxXkZdxPLnRHcsyxp J6Lgs0HubOP2NLIcVpw4xYjo1I6kta9MXOoM4tZBsRe8/YMj+f7gmYE5O2j0Q9XYOdJ0Mh S5X7ksrcwbNhPE4Nmic+O51GAZ1igOk= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-50-pHp6ULcKNDelERNlIA-5_Q-1; Tue, 12 Apr 2022 21:57:06 -0400 X-MC-Unique: pHp6ULcKNDelERNlIA-5_Q-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C1CE22999B20; Wed, 13 Apr 2022 01:57:05 +0000 (UTC) Received: from T590 (ovpn-8-24.pek2.redhat.com [10.72.8.24]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CB6B72166BA4; Wed, 13 Apr 2022 01:56:48 +0000 (UTC) Date: Wed, 13 Apr 2022 09:56:42 +0800 From: Ming Lei To: Mike Snitzer Cc: Jens Axboe , linux-block@vger.kernel.org, dm-devel@redhat.com, Damien Le Moal Subject: Re: [PATCH 5/8] dm: always setup ->orig_bio in alloc_io Message-ID: References: <20220412085616.1409626-1-ming.lei@redhat.com> <20220412085616.1409626-6-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Tue, Apr 12, 2022 at 04:52:40PM -0400, Mike Snitzer wrote: > On Tue, Apr 12 2022 at 4:56P -0400, > Ming Lei wrote: > > > The current DM codes setup ->orig_bio after __map_bio() returns, > > and not only cause kernel panic for dm zone, but also a bit ugly > > and tricky, especially the waiting until ->orig_bio is set in > > dm_submit_bio_remap(). > > > > The reason is that one new bio is cloned from original FS bio to > > represent the mapped part, which just serves io accounting. > > > > Now we have switched to bdev based io accounting interface, and we > > can retrieve sectors/bio_op from both the real original bio and the > > added fields of .sector_offset & .sectors easily, so the new cloned > > bio isn't necessary any more. > > > > Not only fixes dm-zone's kernel panic, but also cleans up dm io > > accounting & split a bit. > > You're conflating quite a few things here. DM zone really has no > business accessing io->orig_bio (dm-zone.c can just as easily inspect > the tio->clone, because it hasn't been remapped yet it reflects the > io->origin_bio, so there is no need to look at io->orig_bio) -- but > yes I clearly broke things during the 5.18 merge and it needs fixing > ASAP. You can just consider the cleanup part of this patches, :-) 1) no late assignment of ->orig_bio, and always set it in alloc_io() 2) no waiting on on ->origi_bio, especially the waiting is done in fast path of dm_submit_bio_remap(). 3) no split for io accounting Thanks, Ming