[PATCH 2/4 Xenial SRU v2] NVMe: Requeue requests on suspended queues

[Tim Gardner]

From: Keith Busch <keith.busch at intel.com>

BugLink: http://bugs.launchpad.net/bugs/1581034

It's possible a request may get to the driver after the nvme queue was
disabled. This has the request requeue if that happens.

Note the request is still "started" by the driver, but requeuing will
clear the start state for timeout handling.

Signed-off-by: Keith Busch <keith.busch at intel.com>
Reviewed-by: Christoph Hellwig <hch at lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn at suse.de>
Reviewed-by: Sagi Grimberg <sagig at mellanox.com>
Signed-off-by: Jens Axboe <axboe at fb.com>
(cherry picked from commit ae1fba20015bca7401db2422fe18c9c049184163)
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
---
 drivers/nvme/host/pci.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 2b2211e..94fd100 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -690,6 +690,11 @@ static int nvme_queue_rq(struct blk_mq_hw_ctx *hctx,
 	blk_mq_start_request(req);
 
 	spin_lock_irq(&nvmeq->q_lock);
+	if (unlikely(nvmeq->cq_vector < 0)) {
+		ret = BLK_MQ_RQ_QUEUE_BUSY;
+		spin_unlock_irq(&nvmeq->q_lock);
+		goto out;
+	}
 	__nvme_submit_cmd(nvmeq, &cmnd);
 	nvme_process_cq(nvmeq);
 	spin_unlock_irq(&nvmeq->q_lock);
-- 
1.9.1