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 1EACDC433F5 for ; Tue, 24 May 2022 01:07:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232550AbiEXBH5 (ORCPT ); Mon, 23 May 2022 21:07:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35308 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229782AbiEXBHz (ORCPT ); Mon, 23 May 2022 21:07:55 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CA6FE45AFA; Mon, 23 May 2022 18:07:52 -0700 (PDT) Received: from kwepemi100022.china.huawei.com (unknown [172.30.72.56]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4L6bd91NKdzjX1W; Tue, 24 May 2022 09:06:53 +0800 (CST) Received: from kwepemm600009.china.huawei.com (7.193.23.164) by kwepemi100022.china.huawei.com (7.221.188.126) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 24 May 2022 09:07:50 +0800 Received: from [10.174.176.73] (10.174.176.73) by kwepemm600009.china.huawei.com (7.193.23.164) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 24 May 2022 09:07:50 +0800 Subject: Re: [PATCH -next v3 3/6] nbd: don't clear 'NBD_CMD_INFLIGHT' flag if request is not completed To: Josef Bacik CC: , , , , , References: <20220521073749.3146892-1-yukuai3@huawei.com> <20220521073749.3146892-4-yukuai3@huawei.com> From: Yu Kuai Message-ID: <6a549193-909b-6f6e-532b-99cd2898ad80@huawei.com> Date: Tue, 24 May 2022 09:07:49 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="gbk"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.176.73] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To kwepemm600009.china.huawei.com (7.193.23.164) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ÔÚ 2022/05/23 22:12, Josef Bacik дµÀ: > On Sat, May 21, 2022 at 03:37:46PM +0800, Yu Kuai wrote: >> Otherwise io will hung because request will only be completed if the >> cmd has the flag 'NBD_CMD_INFLIGHT'. >> >> Fixes: 07175cb1baf4 ("nbd: make sure request completion won't concurrent") >> Signed-off-by: Yu Kuai >> --- >> drivers/block/nbd.c | 18 ++++++++++++++---- >> 1 file changed, 14 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c >> index 2ee1e376d5c4..a0d0910dae2a 100644 >> --- a/drivers/block/nbd.c >> +++ b/drivers/block/nbd.c >> @@ -403,13 +403,14 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req, >> if (!mutex_trylock(&cmd->lock)) >> return BLK_EH_RESET_TIMER; >> >> - if (!__test_and_clear_bit(NBD_CMD_INFLIGHT, &cmd->flags)) { >> + if (!test_bit(NBD_CMD_INFLIGHT, &cmd->flags)) { >> mutex_unlock(&cmd->lock); >> return BLK_EH_DONE; >> } >> >> if (!refcount_inc_not_zero(&nbd->config_refs)) { >> cmd->status = BLK_STS_TIMEOUT; >> + __clear_bit(NBD_CMD_INFLIGHT, &cmd->flags); >> mutex_unlock(&cmd->lock); >> goto done; >> } >> @@ -478,6 +479,7 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req, >> dev_err_ratelimited(nbd_to_dev(nbd), "Connection timed out\n"); >> set_bit(NBD_RT_TIMEDOUT, &config->runtime_flags); >> cmd->status = BLK_STS_IOERR; >> + __clear_bit(NBD_CMD_INFLIGHT, &cmd->flags); >> mutex_unlock(&cmd->lock); >> sock_shutdown(nbd); >> nbd_config_put(nbd); >> @@ -745,7 +747,7 @@ static struct nbd_cmd *nbd_handle_reply(struct nbd_device *nbd, int index, >> cmd = blk_mq_rq_to_pdu(req); >> >> mutex_lock(&cmd->lock); >> - if (!__test_and_clear_bit(NBD_CMD_INFLIGHT, &cmd->flags)) { >> + if (!test_bit(NBD_CMD_INFLIGHT, &cmd->flags)) { >> dev_err(disk_to_dev(nbd->disk), "Suspicious reply %d (status %u flags %lu)", >> tag, cmd->status, cmd->flags); >> ret = -ENOENT; >> @@ -854,8 +856,16 @@ static void recv_work(struct work_struct *work) >> } >> >> rq = blk_mq_rq_from_pdu(cmd); >> - if (likely(!blk_should_fake_timeout(rq->q))) >> - blk_mq_complete_request(rq); >> + if (likely(!blk_should_fake_timeout(rq->q))) { >> + bool complete; >> + >> + mutex_lock(&cmd->lock); >> + complete = __test_and_clear_bit(NBD_CMD_INFLIGHT, >> + &cmd->flags); >> + mutex_unlock(&cmd->lock); >> + if (complete) >> + blk_mq_complete_request(rq); >> + } > > I'd rather this be handled in nbd_handle_reply. We should return with it > cleared if it's ready to be completed. Thanks, Hi, Thanks for your advice, I'll do that in next version. I'll still have to hold the lock to set the bit again in case blk_should_fake_timeout() pass... Thanks, Kuai > > Josef > . >