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 E89D7CCA480 for ; Fri, 15 Jul 2022 15:46:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235536AbiGOPqx (ORCPT ); Fri, 15 Jul 2022 11:46:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51208 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235179AbiGOPqr (ORCPT ); Fri, 15 Jul 2022 11:46:47 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4E4CA231; Fri, 15 Jul 2022 08:46:47 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id DFBEB62135; Fri, 15 Jul 2022 15:46:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 65BE5C34115; Fri, 15 Jul 2022 15:46:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1657900006; bh=1pP6wpTZR6yxJttIfhQ8GaI8CR+vOrFTZHxcwN15uk0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nTS1MBom8JQTTyxEVLiCJsH0hjcLXRd+KWRW8j3+FwNB94NtVwxVS2b96USqC+sj4 X/y9CH5O8YMTLBPq2aLd6pHgYwMMkzcQE8XH7EE5DFEuPgy48tsQv1wK1nuHVA8sjv d9LxY2RmBRhHoOoqQHLHJmdKo67NuGc+5QL5hrDXhUzcvX1aesCIXJLRFKlGsLsT+U rvJ9XJYf3yOkXRvfjwP0iY+hRoZsNgrRJ1SbPWaq5DYVaa4NkP9SzzfADd2GOYlAmX BGuzgB7BqNF8zrOFWIG+/Hiit3qJ6zHtel3LuLoAF7S4p7KhMQcV/CU9YTJSlfi0if u/t2DHgvbMY0g== From: SeongJae Park To: Andrii Chepurnyi Cc: Oleksandr , SeongJae Park , roger.pau@citrix.com, jgross@suse.com, axboe@kernel.dk, boris.ostrovsky@oracle.com, mheyne@amazon.de, xen-devel@lists.xenproject.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2] xen-blkback: fix persistent grants negotiation Date: Fri, 15 Jul 2022 15:46:43 +0000 Message-Id: <20220715154643.54334-1-sj@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Oleksandr, thank you for Cc-ing Andrii. Andrii, thank you for the comment! On Fri, 15 Jul 2022 15:00:10 +0300 Andrii Chepurnyi wrote: > [-- Attachment #1: Type: text/plain, Size: 5237 bytes --] > > Hello All, > > I faced the mentioned issue recently and just to bring more context here is > our setup: > We use pvblock backend for Android guest. It starts using u-boot with > pvblock support(which frontend doesn't support the persistent grants > feature), later it loads and starts the Linux kernel(which frontend > supports the persistent grants feature). So in total, we have sequent two > different frontends reconnection, the first of which doesn't support > persistent grants. > So the original patch [1] perfectly solves the original issue and provides > the ability to use persistent grants after the reconnection when Linux > frontend which supports persistent grants comes into play. > At the same time [2] will disable the persistent grants feature for the > first and second frontend. Thank you for this great explanation of your situation. > Is it possible to keep [1] as is? Yes, my concerns about Max's original patch[1] are conflicting behavior description in the document[1] and different behavior on blkfront-side 'feature_persistent' parameter. I will post Max's patch again with patches for blkfront behavior change and Documents updates. [1] https://lore.kernel.org/xen-devel/20220121102309.27802-1-sj@kernel.org/ Thanks, SJ > > [1] > https://lore.kernel.org/xen-devel/20220106091013.126076-1-mheyne@amazon.de/ > [2] https://lore.kernel.org/xen-devel/20220714224410.51147-1-sj@kernel.org/ > > Best regards, > Andrii > > On Fri, Jul 15, 2022 at 1:15 PM Oleksandr wrote: > > > > > On 15.07.22 01:44, SeongJae Park wrote: > > > > > > Hello all. > > > > Adding Andrii Chepurnyi to CC who have played with the use-case which > > required reconnect recently and faced some issues with > > feature_persistent handling. [...]