Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Sergei Shtepa <sergei.shtepa@veeam.com>
To:     <snitzer@redhat.com>, <agk@redhat.com>, <hare@suse.de>,
        <song@kernel.org>, <axboe@kernel.dk>, <dm-devel@redhat.com>,
        <linux-block@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-raid@vger.kernel.org>, <linux-api@vger.kernel.org>
CC:     <sergei.shtepa@veeam.com>, <pavel.tide@veeam.com>
Subject: [PATCH v6 1/4] block: add blk_mq_is_queue_frozen()
Date:   Wed, 3 Mar 2021 15:30:15 +0300
Message-ID: <1614774618-22410-2-git-send-email-sergei.shtepa@veeam.com>
In-Reply-To: <1614774618-22410-1-git-send-email-sergei.shtepa@veeam.com>
References: <1614774618-22410-1-git-send-email-sergei.shtepa@veeam.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

blk_mq_is_queue_frozen() allow to assert that the queue is frozen.

Signed-off-by: Sergei Shtepa <sergei.shtepa@veeam.com>
---
 block/blk-mq.c         | 12 ++++++++++++
 include/linux/blk-mq.h |  1 +
 2 files changed, 13 insertions(+)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index d4d7c1caa439..d5e7122789fc 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -161,6 +161,18 @@ int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
 }
 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout);
 
+bool blk_mq_is_queue_frozen(struct request_queue *q)
+{
+	bool ret;
+
+	mutex_lock(&q->mq_freeze_lock);
+	ret = percpu_ref_is_dying(&q->q_usage_counter) && percpu_ref_is_zero(&q->q_usage_counter);
+	mutex_unlock(&q->mq_freeze_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(blk_mq_is_queue_frozen);
+
 /*
  * Guarantee no request is in use, so we can change any data structure of
  * the queue afterward.
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 2c473c9b8990..6f01971abf7b 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -533,6 +533,7 @@ void blk_freeze_queue_start(struct request_queue *q);
 void blk_mq_freeze_queue_wait(struct request_queue *q);
 int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
 				     unsigned long timeout);
+bool blk_mq_is_queue_frozen(struct request_queue *q);
 
 int blk_mq_map_queues(struct blk_mq_queue_map *qmap);
 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues);
-- 
2.20.1