From patchwork Wed Aug 31 15:51:36 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ziyang Zhang X-Patchwork-Id: 12960992 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 EC2BEECAAD4 for ; Wed, 31 Aug 2022 15:54:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230181AbiHaPy6 (ORCPT ); Wed, 31 Aug 2022 11:54:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38416 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231419AbiHaPyn (ORCPT ); Wed, 31 Aug 2022 11:54:43 -0400 Received: from out30-43.freemail.mail.aliyun.com (out30-43.freemail.mail.aliyun.com [115.124.30.43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C98E1AB4FE; Wed, 31 Aug 2022 08:54:41 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R161e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046050;MF=ziyangzhang@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0VNrdoMu_1661961264; Received: from localhost.localdomain(mailfrom:ZiyangZhang@linux.alibaba.com fp:SMTPD_---0VNrdoMu_1661961264) by smtp.aliyun-inc.com; Wed, 31 Aug 2022 23:54:37 +0800 From: ZiyangZhang To: ming.lei@redhat.com, axboe@kernel.dk Cc: xiaoguang.wang@linux.alibaba.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, joseph.qi@linux.alibaba.com, ZiyangZhang Subject: [RFC PATCH V2 6/6] ublk_drv: add START_USER_RECOVERY and END_USER_RECOVERY support Date: Wed, 31 Aug 2022 23:51:36 +0800 Message-Id: <20220831155136.23434-7-ZiyangZhang@linux.alibaba.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20220831155136.23434-1-ZiyangZhang@linux.alibaba.com> References: <20220831155136.23434-1-ZiyangZhang@linux.alibaba.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org START_USER_RECOVERY and END_USER_RECOVERY are two new control commands to support user recovery feature. After a crash, user should send START_USER_RECOVERY, it will: (1) check if (a)current ublk_device is UBLK_S_DEV_RECOVERING which was set by monitor_work and (b)the file struct is released. We always expect crash of the ublksrv 'process', not exit of a single ubq_daemon 'pthread'. (2) reinit all ubqs, including: (a) put the dying task(thread) and reset ->ubq_daemon to NULL. (b) reset all ublk_io. (3) reset ub->mm to NULL. Then, user should start a new 'process' and send FETCH_REQ on each ubq_daemon. Finally, user should send END_USER_RECOVERY, it will: (1) wait for all new ubq_daemons getting ready. (2) unquiesce the request queue and expect incoming ublk_queue_rq() (3) convert state to UBLK_S_DEV_LIVE (4) schedule monitor_work again Signed-off-by: ZiyangZhang --- drivers/block/ublk_drv.c | 130 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 130 insertions(+) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 0e185d1fa2c4..2d1f3e032606 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -1964,6 +1964,130 @@ static int ublk_ctrl_set_params(struct io_uring_cmd *cmd) return ret; } +static void ublk_queue_start_recovery(struct ublk_device *ub, struct ublk_queue *ubq) +{ + int i; + + /* All old ioucmds have to be completed/canceled by io_uring_cmd_done(). */ + WARN_ON_ONCE(ubq->nr_io_ready); + + /* old daemon is PF_EXITING, put it now */ + put_task_struct(ubq->ubq_daemon); + /* have to set it to NULL, otherwise ub won't accept new FETCH_REQ */ + ubq->ubq_daemon = NULL; + + for (i = 0; i < ubq->q_depth; i++) { + struct ublk_io *io = &ubq->ios[i]; + + /* forget everything now and be ready for new FETCH_REQ */ + io->flags = 0; + io->cmd = NULL; + io->addr = 0; + } +} + +static int ublk_ctrl_start_recovery(struct io_uring_cmd *cmd) +{ + struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd; + struct ublk_device *ub; + int ret = -EINVAL; + int i; + + ub = ublk_get_device_from_id(header->dev_id); + if (!ub) + return ret; + + mutex_lock(&ub->mutex); + + if (!ublk_can_use_recovery(ub)) + goto out_unlock; + + /* + * START_RECOVERY is only allowd after: + * + * (1) UB_STATE_OPEN is not set, which means the dying process is exited + * and related io_uring ctx is freed so file struct of /dev/ublkcX is + * released. + * + * (2) UBLK_S_DEV_RECOVERING is set, which means the monitor_work: + * (a)has requeued all inflight rqs whose io_flags is ACTIVE + * (b)has requeued/aborted all inflight rqs whose io_flags is NOT ACTIVE + * (c)has completed/camceled all ioucmds owned by ther dying process + */ + if (test_bit(UB_STATE_OPEN, &ub->state) || + ub->dev_info.state != UBLK_S_DEV_RECOVERING) { + ret = -EBUSY; + goto out_unlock; + } + + pr_devel("%s: start recovery for dev id %d.\n", __func__, header->dev_id); + + for (i = 0; i < ub->dev_info.nr_hw_queues; i++) { + struct ublk_queue *ubq = ublk_get_queue(ub, i); + + WARN_ON_ONCE(!(ubq->ubq_daemon && ubq_daemon_is_dying(ubq))); + pr_devel("%s: prepare for recovering qid %d\n", __func__, ubq->q_id); + ublk_queue_start_recovery(ub, ubq); + } + + /* set to NULL, otherwise new ubq_daemon cannot mmap the io_cmd_buf */ + ub->mm = NULL; + ub->nr_queues_ready = 0; + init_completion(&ub->completion); + ret = 0; + + out_unlock: + mutex_unlock(&ub->mutex); + ublk_put_device(ub); + return ret; +} + +static int ublk_ctrl_end_recovery(struct io_uring_cmd *cmd) +{ + struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd; + int ublksrv_pid = (int)header->data[0]; + struct ublk_device *ub; + int ret = -EINVAL; + + ub = ublk_get_device_from_id(header->dev_id); + if (!ub) + return ret; + + pr_devel("%s: Waiting for new ubq_daemon is ready, dev id %d...\n", + __func__, header->dev_id); + /* wait until new ubq_daemon sending all FETCH_REQ */ + wait_for_completion_interruptible(&ub->completion); + pr_devel("%s: All new ubq_daemon is ready, dev id %d\n", + __func__, header->dev_id); + + mutex_lock(&ub->mutex); + + if (!ublk_can_use_recovery(ub)) + goto out_unlock; + + /* monitor_work should set UBLK_S_DEV_RECOVERING */ + if (ub->dev_info.state != UBLK_S_DEV_RECOVERING) { + ret = -EBUSY; + goto out_unlock; + } + ub->dev_info.ublksrv_pid = ublksrv_pid; + pr_devel("%s: new ublksrv_pid %d, dev id %d\n", + __func__, ublksrv_pid, header->dev_id); + blk_mq_unquiesce_queue(ub->ub_disk->queue); + pr_devel("%s: queue unquiesced, dev id %d.\n", + __func__, header->dev_id); + + ub->dev_info.state = UBLK_S_DEV_LIVE; + schedule_delayed_work(&ub->monitor_work, UBLK_DAEMON_MONITOR_PERIOD); + /* We are good to redo requests now */ + blk_mq_kick_requeue_list(ub->ub_disk->queue); + ret = 0; + out_unlock: + mutex_unlock(&ub->mutex); + ublk_put_device(ub); + return ret; +} + static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags) { @@ -2005,6 +2129,12 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd, case UBLK_CMD_SET_PARAMS: ret = ublk_ctrl_set_params(cmd); break; + case UBLK_CMD_START_USER_RECOVERY: + ret = ublk_ctrl_start_recovery(cmd); + break; + case UBLK_CMD_END_USER_RECOVERY: + ret = ublk_ctrl_end_recovery(cmd); + break; default: break; }