From: Sagi Grimberg <sagi@grimberg.me>
Date: Thu, 21 Dec 2017 15:07:27 +0200
Subject: nvme-mpath: fix last path removal during traffic
Patch-mainline: v4.15-rc8
Git-commit: 479a322fb729d657d34706ccf8dd12916f36628f
References: FATE#323952, FATE#322506

In case our last path is removed during traffic, we can end up requeueing
the bio(s) but never schedule the actual requeue work as upper layers
still have open handles on the mpath device node.

Fix this by scheduling requeue work if the namespace being removed is
the last path in the ns_head path list.

Fixes: 32acab3181c7 ("nvme: implement multipath access to nvme subsystems")
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Johannes Thumshirn <jthumshirn@suse.de>
---
 drivers/nvme/host/core.c |    1 +
 drivers/nvme/host/nvme.h |   12 ++++++++++++
 2 files changed, 13 insertions(+)

--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2986,6 +2986,7 @@ static void nvme_ns_remove(struct nvme_n
 	mutex_unlock(&ns->ctrl->namespaces_mutex);
 
 	synchronize_srcu(&ns->head->srcu);
+	nvme_mpath_check_last_path(ns);
 	nvme_put_ns(ns);
 }
 
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -416,6 +416,15 @@ static inline void nvme_mpath_clear_curr
 		rcu_assign_pointer(head->current_path, NULL);
 }
 struct nvme_ns *nvme_find_path(struct nvme_ns_head *head);
+
+static inline void nvme_mpath_check_last_path(struct nvme_ns *ns)
+{
+	struct nvme_ns_head *head = ns->head;
+
+	if (head->disk && list_empty(&head->list))
+		kblockd_schedule_work(&head->requeue_work);
+}
+
 #else
 static inline void nvme_failover_req(struct request *req)
 {
@@ -447,6 +456,9 @@ static inline void nvme_mpath_remove_dis
 static inline void nvme_mpath_clear_current_path(struct nvme_ns *ns)
 {
 }
+static inline void nvme_mpath_check_last_path(struct nvme_ns *ns)
+{
+}
 #endif /* CONFIG_NVME_MULTIPATH */
 
 #ifdef CONFIG_NVM