From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f68.google.com ([74.125.83.68]:34586 "EHLO mail-pg0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752740AbdC0MHl (ORCPT ); Mon, 27 Mar 2017 08:07:41 -0400 Received: by mail-pg0-f68.google.com with SMTP id o123so9635234pga.1 for ; Mon, 27 Mar 2017 05:07:40 -0700 (PDT) From: Ming Lei To: Jens Axboe , linux-block@vger.kernel.org, Christoph Hellwig Cc: Bart Van Assche , Hannes Reinecke , Ming Lei , Tejun Heo Subject: [PATCH v3 4/4] block: block new I/O just after queue is set as dying Date: Mon, 27 Mar 2017 20:06:58 +0800 Message-Id: <20170327120658.29864-5-tom.leiming@gmail.com> In-Reply-To: <20170327120658.29864-1-tom.leiming@gmail.com> References: <20170327120658.29864-1-tom.leiming@gmail.com> Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org Before commit 780db2071a(blk-mq: decouble blk-mq freezing from generic bypassing), the dying flag is checked before entering queue, and Tejun converts the checking into .mq_freeze_depth, and assumes the counter is increased just after dying flag is set. Unfortunately we doesn't do that in blk_set_queue_dying(). This patch calls blk_freeze_queue_start() in blk_set_queue_dying(), so that we can block new I/O coming once the queue is set as dying. Given blk_set_queue_dying() is always called in remove path of block device, and queue will be cleaned up later, we don't need to worry about undoing the counter. Cc: Bart Van Assche Cc: Tejun Heo Reviewed-by: Hannes Reinecke Signed-off-by: Ming Lei --- block/blk-core.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 60f364e1d36b..e22c4ea002ec 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -500,6 +500,13 @@ void blk_set_queue_dying(struct request_queue *q) queue_flag_set(QUEUE_FLAG_DYING, q); spin_unlock_irq(q->queue_lock); + /* + * When queue DYING flag is set, we need to block new req + * entering queue, so we call blk_freeze_queue_start() to + * prevent I/O from crossing blk_queue_enter(). + */ + blk_freeze_queue_start(q); + if (q->mq_ops) blk_mq_wake_waiters(q); else { @@ -672,9 +679,9 @@ int blk_queue_enter(struct request_queue *q, bool nowait) /* * read pair of barrier in blk_freeze_queue_start(), * we need to order reading __PERCPU_REF_DEAD flag of - * .q_usage_counter and reading .mq_freeze_depth, - * otherwise the following wait may never return if the - * two reads are reordered. + * .q_usage_counter and reading .mq_freeze_depth or + * queue dying flag, otherwise the following wait may + * never return if the two reads are reordered. */ smp_rmb(); -- 2.9.3