From patchwork Mon Oct 9 23:14:00 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bart Van Assche X-Patchwork-Id: 9994593 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 5CEAD60223 for ; Mon, 9 Oct 2017 23:14:18 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4F71A1FF1D for ; Mon, 9 Oct 2017 23:14:18 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4434D1FF8F; Mon, 9 Oct 2017 23:14:18 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C11561FF41 for ; Mon, 9 Oct 2017 23:14:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755707AbdJIXOP (ORCPT ); Mon, 9 Oct 2017 19:14:15 -0400 Received: from esa5.hgst.iphmx.com ([216.71.153.144]:21756 "EHLO esa5.hgst.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755645AbdJIXON (ORCPT ); Mon, 9 Oct 2017 19:14:13 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=wdc.com; i=@wdc.com; q=dns/txt; s=dkim.wdc.com; t=1507590853; x=1539126853; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=9UEdQ4IIGZ2zxcC2/mjYzyq0O5yk82Q633wxEGOHYdA=; b=M1NTlp242xcNnVpjR0UDEJwEYspt2Qu795QS+v1hqYUAXUnRUoymDv1h lSXKFFYezst3Z4omw4o1Ay+y9hAH1qHwUNUwKozyfv0Psnh7+b8HP2n1K huSsM6AEuzvax+oT+CJ33CPOY9X9KZqCIY/SDPVxN6Q2DoDXYuk2qckCk tXsFyeRZ5pyccUx7r4QGXcJAFlQZNvkLwuVtPhKVwO/47dOpOp0hEXraH Hugh+65Zl1gn3o9DfrKX46DQTblVg6QzzzjXiBCqSvU5Gdx3Woq2v0sFe /SI4Duw5Mn/XUrjeX6+HCsrXdBu/WpsjOXhyGH3A58GyJzYJJkmMEZQjK A==; X-IronPort-AV: E=Sophos;i="5.42,501,1500912000"; d="scan'208";a="57150538" Received: from sjappemgw11.hgst.com (HELO sjappemgw12.hgst.com) ([199.255.44.62]) by ob1.hgst.iphmx.com with ESMTP; 10 Oct 2017 07:14:12 +0800 Received: from thinkpad-bart.sdcorp.global.sandisk.com (HELO thinkpad-bart.int.fusionio.com) ([10.11.172.152]) by sjappemgw12.hgst.com with ESMTP; 09 Oct 2017 16:14:02 -0700 From: Bart Van Assche To: Jens Axboe Cc: linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, Christoph Hellwig , "Martin K . Petersen" , =Oleksandr Natalenko , "Luis R . Rodriguez" , Ming Lei , Bart Van Assche , Hannes Reinecke , Johannes Thumshirn Subject: [PATCH v7 9/9] block, scsi: Make SCSI quiesce and resume work reliably Date: Mon, 9 Oct 2017 16:14:00 -0700 Message-Id: <20171009231400.562-10-bart.vanassche@wdc.com> X-Mailer: git-send-email 2.14.2 In-Reply-To: <20171009231400.562-1-bart.vanassche@wdc.com> References: <20171009231400.562-1-bart.vanassche@wdc.com> Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The contexts from which a SCSI device can be quiesced or resumed are: * Writing into /sys/class/scsi_device/*/device/state. * SCSI parallel (SPI) domain validation. * The SCSI device power management methods. See also scsi_bus_pm_ops. It is essential during suspend and resume that neither the filesystem state nor the filesystem metadata in RAM changes. This is why while the hibernation image is being written or restored that SCSI devices are quiesced. The SCSI core quiesces devices through scsi_device_quiesce() and scsi_device_resume(). In the SDEV_QUIESCE state execution of non-preempt requests is deferred. This is realized by returning BLKPREP_DEFER from inside scsi_prep_state_check() for quiesced SCSI devices. Avoid that a full queue prevents power management requests to be submitted by deferring allocation of non-preempt requests for devices in the quiesced state. This patch has been tested by running the following commands and by verifying that after resume the fio job is still running: for d in /sys/class/block/sd*[a-z]; do hcil=$(readlink "$d/device") hcil=${hcil#../../../} echo 4 > "$d/queue/nr_requests" echo 1 > "/sys/class/scsi_device/$hcil/device/queue_depth" done bdev=$(readlink /dev/disk/by-uuid/5217d83f-213e-4b42-b86e-20013325ba6c) bdev=${bdev#../../} hcil=$(readlink "/sys/block/$bdev/device") hcil=${hcil#../../../} fio --name="$bdev" --filename="/dev/$bdev" --buffered=0 --bs=512 --rw=randread \ --ioengine=libaio --numjobs=4 --iodepth=16 --iodepth_batch=1 --thread \ --loops=$((2**31)) & pid=$! sleep 1 systemctl hibernate sleep 10 kill $pid Reported-by: Oleksandr Natalenko References: "I/O hangs after resuming from suspend-to-ram" (https://marc.info/?l=linux-block&m=150340235201348). Signed-off-by: Bart Van Assche Cc: Martin K. Petersen Cc: Ming Lei Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: Johannes Thumshirn Tested-By: Martin Steigerwald --- block/blk-core.c | 42 +++++++++++++++++++++++++++++++++++------- block/blk-mq.c | 4 ++-- block/blk-timeout.c | 2 +- drivers/scsi/scsi_lib.c | 28 ++++++++++++++++++---------- fs/block_dev.c | 4 ++-- include/linux/blkdev.h | 2 +- 6 files changed, 59 insertions(+), 23 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index ed992cbd107f..3847ea42e341 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -372,6 +372,7 @@ void blk_clear_preempt_only(struct request_queue *q) spin_lock_irqsave(q->queue_lock, flags); queue_flag_clear(QUEUE_FLAG_PREEMPT_ONLY, q); + wake_up_all(&q->mq_freeze_wq); spin_unlock_irqrestore(q->queue_lock, flags); } EXPORT_SYMBOL_GPL(blk_clear_preempt_only); @@ -793,15 +794,40 @@ struct request_queue *blk_alloc_queue(gfp_t gfp_mask) } EXPORT_SYMBOL(blk_alloc_queue); -int blk_queue_enter(struct request_queue *q, bool nowait) +/** + * blk_queue_enter() - try to increase q->q_usage_counter + * @q: request queue pointer + * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PREEMPT + */ +int blk_queue_enter(struct request_queue *q, unsigned int flags) { + const bool preempt = flags & BLK_MQ_REQ_PREEMPT; + while (true) { + bool success = false; int ret; - if (percpu_ref_tryget_live(&q->q_usage_counter)) + rcu_read_lock_sched(); + if (percpu_ref_tryget_live(&q->q_usage_counter)) { + /* + * The code that sets the PREEMPT_ONLY flag is + * responsible for ensuring that that flag is globally + * visible before the queue is unfrozen. + */ + if (preempt || !blk_queue_preempt_only(q)) { + success = true; + } else { + percpu_ref_put(&q->q_usage_counter); + WARN_ONCE("%s: Attempt to allocate non-preempt request in preempt-only mode.\n", + kobject_name(q->kobj.parent)); + } + } + rcu_read_unlock_sched(); + + if (success) return 0; - if (nowait) + if (flags & BLK_MQ_REQ_NOWAIT) return -EBUSY; /* @@ -814,7 +840,8 @@ int blk_queue_enter(struct request_queue *q, bool nowait) smp_rmb(); ret = wait_event_interruptible(q->mq_freeze_wq, - !atomic_read(&q->mq_freeze_depth) || + (atomic_read(&q->mq_freeze_depth) == 0 && + (preempt || !blk_queue_preempt_only(q))) || blk_queue_dying(q)); if (blk_queue_dying(q)) return -ENODEV; @@ -1442,8 +1469,7 @@ static struct request *blk_old_get_request(struct request_queue *q, /* create ioc upfront */ create_io_context(gfp_mask, q->node); - ret = blk_queue_enter(q, !(gfp_mask & __GFP_DIRECT_RECLAIM) || - (op & REQ_NOWAIT)); + ret = blk_queue_enter(q, flags); if (ret) return ERR_PTR(ret); spin_lock_irq(q->queue_lock); @@ -2264,8 +2290,10 @@ blk_qc_t generic_make_request(struct bio *bio) current->bio_list = bio_list_on_stack; do { struct request_queue *q = bio->bi_disk->queue; + unsigned int flags = bio->bi_opf & REQ_NOWAIT ? + BLK_MQ_REQ_NOWAIT : 0; - if (likely(blk_queue_enter(q, bio->bi_opf & REQ_NOWAIT) == 0)) { + if (likely(blk_queue_enter(q, flags) == 0)) { struct bio_list lower, same; /* Create a fresh bio_list for all subordinate requests */ diff --git a/block/blk-mq.c b/block/blk-mq.c index bdbfe760bda0..44a06e8541f2 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -386,7 +386,7 @@ struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op, struct request *rq; int ret; - ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT); + ret = blk_queue_enter(q, flags); if (ret) return ERR_PTR(ret); @@ -425,7 +425,7 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, if (hctx_idx >= q->nr_hw_queues) return ERR_PTR(-EIO); - ret = blk_queue_enter(q, true); + ret = blk_queue_enter(q, flags); if (ret) return ERR_PTR(ret); diff --git a/block/blk-timeout.c b/block/blk-timeout.c index e3e9c9771d36..1eba71486716 100644 --- a/block/blk-timeout.c +++ b/block/blk-timeout.c @@ -134,7 +134,7 @@ void blk_timeout_work(struct work_struct *work) struct request *rq, *tmp; int next_set = 0; - if (blk_queue_enter(q, true)) + if (blk_queue_enter(q, BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PREEMPT)) return; spin_lock_irqsave(q->queue_lock, flags); diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 1c16a247fae6..a3cf36c8079b 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -2926,21 +2926,29 @@ static void scsi_wait_for_queuecommand(struct scsi_device *sdev) int scsi_device_quiesce(struct scsi_device *sdev) { + struct request_queue *q = sdev->request_queue; int err; + /* If the SCSI device already has been quiesced, do nothing. */ + if (blk_set_preempt_only(q)) + return 0; + + /* + * Since blk_mq_freeze_queue() calls synchronize_rcu() indirectly the + * effect of blk_set_preempt_only() will be visible for + * percpu_ref_tryget() callers that occur after the queue + * unfreeze. See also https://lwn.net/Articles/573497/. + */ + blk_mq_freeze_queue(q); + blk_mq_unfreeze_queue(q); + mutex_lock(&sdev->state_mutex); err = scsi_device_set_state(sdev, SDEV_QUIESCE); - mutex_unlock(&sdev->state_mutex); - if (err) - return err; + blk_clear_preempt_only(q); + mutex_unlock(&sdev->state_mutex); - scsi_run_queue(sdev->request_queue); - while (atomic_read(&sdev->device_busy)) { - msleep_interruptible(200); - scsi_run_queue(sdev->request_queue); - } - return 0; + return err; } EXPORT_SYMBOL(scsi_device_quiesce); @@ -2962,7 +2970,7 @@ void scsi_device_resume(struct scsi_device *sdev) mutex_lock(&sdev->state_mutex); if (sdev->sdev_state == SDEV_QUIESCE && scsi_device_set_state(sdev, SDEV_RUNNING) == 0) - scsi_run_queue(sdev->request_queue); + blk_clear_preempt_only(sdev->request_queue); mutex_unlock(&sdev->state_mutex); } EXPORT_SYMBOL(scsi_device_resume); diff --git a/fs/block_dev.c b/fs/block_dev.c index 93d088ffc05c..98cf2d7ee9d3 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -674,7 +674,7 @@ int bdev_read_page(struct block_device *bdev, sector_t sector, if (!ops->rw_page || bdev_get_integrity(bdev)) return result; - result = blk_queue_enter(bdev->bd_queue, false); + result = blk_queue_enter(bdev->bd_queue, 0); if (result) return result; result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, false); @@ -710,7 +710,7 @@ int bdev_write_page(struct block_device *bdev, sector_t sector, if (!ops->rw_page || bdev_get_integrity(bdev)) return -EOPNOTSUPP; - result = blk_queue_enter(bdev->bd_queue, false); + result = blk_queue_enter(bdev->bd_queue, 0); if (result) return result; diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 89555eea742b..0a4638cf0687 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -967,7 +967,7 @@ extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t, extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t, struct scsi_ioctl_command __user *); -extern int blk_queue_enter(struct request_queue *q, bool nowait); +extern int blk_queue_enter(struct request_queue *q, unsigned int flags); extern void blk_queue_exit(struct request_queue *q); extern void blk_start_queue(struct request_queue *q); extern void blk_start_queue_async(struct request_queue *q);