[PATCH 2/3] nvme: add 'queue_if_no_path' semantics

[Hannes Reinecke]

Instead of reverting the handling of the 'last' path for all
setups we should be restricting it to the non-fabrics case.
So add a 'queue_if_no_path' flag which will switch to the
current behaviour; disabling this flag will revert to the
original (pre-fabrics) behaviour.
And set this flag per default for fabrics.

Signed-off-by: Hannes Reinecke <hare at suse.de>
---
 drivers/nvme/host/core.c      | 7 ++++++-
 drivers/nvme/host/multipath.c | 4 ++++
 drivers/nvme/host/nvme.h      | 1 +
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index af950d58c562..79b88b4c448f 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -474,8 +474,11 @@ static void nvme_free_ns_head(struct kref *ref)
 	struct nvme_ns_head *head =
 		container_of(ref, struct nvme_ns_head, ref);
 
-	if (head->disk)
+	if (head->disk) {
+		if (test_bit(NVME_NSHEAD_QUEUE_IF_NO_PATH, &head->flags))
+			nvme_mpath_remove_disk(head);
 		put_disk(head->disk);
+	}
 	ida_simple_remove(&head->subsys->ns_ida, head->instance);
 	cleanup_srcu_struct(&head->srcu);
 	nvme_put_subsystem(head->subsys);
@@ -3686,6 +3689,8 @@ static struct nvme_ns_head *nvme_alloc_ns_head(struct nvme_ctrl *ctrl,
 	head->subsys = ctrl->subsys;
 	head->ns_id = nsid;
 	head->ids = *ids;
+	if (ctrl->ops->flags & NVME_F_FABRICS)
+		set_bit(NVME_NSHEAD_QUEUE_IF_NO_PATH, &head->flags);
 	kref_init(&head->ref);
 
 	ret = __nvme_check_ids(ctrl->subsys, head);
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 55045291b4de..05c4fbc35bb2 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -682,6 +682,10 @@ void nvme_mpath_remove_disk(struct nvme_ns_head *head)
 {
 	if (!head->disk)
 		return;
+	if (test_bit(NVME_NSHEAD_QUEUE_IF_NO_PATH, &head->flags)) {
+		kblockd_schedule_work(&head->requeue_work);
+		return;
+	}
 	if (head->disk->flags & GENHD_FL_UP)
 		del_gendisk(head->disk);
 	blk_set_queue_dying(head->disk->queue);
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index b6180bb3361d..baf4a84918d8 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -411,6 +411,7 @@ struct nvme_ns_head {
 	struct mutex		lock;
 	unsigned long		flags;
 #define NVME_NSHEAD_DISK_LIVE	0
+#define NVME_NSHEAD_QUEUE_IF_NO_PATH 1
 	struct nvme_ns __rcu	*current_path[];
 #endif
 };
-- 
2.16.4