Commit 1f021341 authored by Keith Busch's avatar Keith Busch
Browse files

nvme-multipath: defer partition scanning 



We need to suppress the partition scan from occuring within the
controller's scan_work context. If a path error occurs here, the IO will
wait until a path becomes available or all paths are torn down, but that
action also occurs within scan_work, so it would deadlock. Defer the
partion scan to a different context that does not block scan_work.

Reported-by: default avatarHannes Reinecke <hare@suse.de>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarKeith Busch <kbusch@kernel.org>
parent 0ce96a67

drivers/nvme/host/multipath.c

+33 −6
Original line number Diff line number Diff line
@@ -579,6 +579,20 @@ static int nvme_add_ns_head_cdev(struct nvme_ns_head *head) 
	return ret;

}



static void nvme_partition_scan_work(struct work_struct *work)

{

	struct nvme_ns_head *head =

		container_of(work, struct nvme_ns_head, partition_scan_work);



	if (WARN_ON_ONCE(!test_and_clear_bit(GD_SUPPRESS_PART_SCAN,

					     &head->disk->state)))

		return;



	mutex_lock(&head->disk->open_mutex);

	bdev_disk_changed(head->disk, false);

	mutex_unlock(&head->disk->open_mutex);

}



static void nvme_requeue_work(struct work_struct *work)

{

	struct nvme_ns_head *head =
@@ -605,6 +619,7 @@ int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, struct nvme_ns_head *head) 
	bio_list_init(&head->requeue_list);

	spin_lock_init(&head->requeue_lock);

	INIT_WORK(&head->requeue_work, nvme_requeue_work);

	INIT_WORK(&head->partition_scan_work, nvme_partition_scan_work);



	/*

	 * Add a multipath node if the subsystems supports multiple controllers.
@@ -628,6 +643,16 @@ int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, struct nvme_ns_head *head) 
		return PTR_ERR(head->disk);

	head->disk->fops = &nvme_ns_head_ops;

	head->disk->private_data = head;



	/*

	 * We need to suppress the partition scan from occuring within the

	 * controller's scan_work context. If a path error occurs here, the IO

	 * will wait until a path becomes available or all paths are torn down,

	 * but that action also occurs within scan_work, so it would deadlock.

	 * Defer the partion scan to a different context that does not block

	 * scan_work.

	 */

	set_bit(GD_SUPPRESS_PART_SCAN, &head->disk->state);

	sprintf(head->disk->disk_name, "nvme%dn%d",

			ctrl->subsys->instance, head->instance);

	return 0;
@@ -654,6 +679,7 @@ static void nvme_mpath_set_live(struct nvme_ns *ns) 
			return;

		}

		nvme_add_ns_head_cdev(head);

		kblockd_schedule_work(&head->partition_scan_work);

	}



	mutex_lock(&head->lock);
@@ -973,14 +999,14 @@ void nvme_mpath_shutdown_disk(struct nvme_ns_head *head) 
		return;

	if (test_and_clear_bit(NVME_NSHEAD_DISK_LIVE, &head->flags)) {

		nvme_cdev_del(&head->cdev, &head->cdev_device);

		del_gendisk(head->disk);

	}

		/*

		 * requeue I/O after NVME_NSHEAD_DISK_LIVE has been cleared

		 * to allow multipath to fail all I/O.

		 */

		synchronize_srcu(&head->srcu);

		kblockd_schedule_work(&head->requeue_work);

		del_gendisk(head->disk);

	}

}



void nvme_mpath_remove_disk(struct nvme_ns_head *head)
@@ -990,6 +1016,7 @@ void nvme_mpath_remove_disk(struct nvme_ns_head *head) 
	/* make sure all pending bios are cleaned up */

	kblockd_schedule_work(&head->requeue_work);

	flush_work(&head->requeue_work);

	flush_work(&head->partition_scan_work);

	put_disk(head->disk);

}

drivers/nvme/host/nvme.h

+1 −0
Original line number Diff line number Diff line
@@ -494,6 +494,7 @@ struct nvme_ns_head { 
	struct bio_list		requeue_list;

	spinlock_t		requeue_lock;

	struct work_struct	requeue_work;

	struct work_struct	partition_scan_work;

	struct mutex		lock;

	unsigned long		flags;

#define NVME_NSHEAD_DISK_LIVE	0