nvme: fix block device naming collision

The issue exists when multipath is enabled and the namespace is
shared, but all the other controller checks at nvme_is_unique_nsid()
are false. The reason for this issue is that nvme_is_unique_nsid()
returns false when is called from nvme_mpath_alloc_disk() due to an
uninitialized value of head->shared. The patch fixes it by setting
head->shared before nvme_mpath_alloc_disk() is called.

Fixes: 5974ea7c ("nvme: allow duplicate NSIDs for private namespaces")
Signed-off-by: Israel Rukshin <israelr@nvidia.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/core.c

@@ -3786,7 +3786,7 @@ static int nvme_add_ns_cdev(struct nvme_ns *ns)
 }
 
 static struct nvme_ns_head *nvme_alloc_ns_head(struct nvme_ctrl *ctrl,
-		unsigned nsid, struct nvme_ns_ids *ids)
+		unsigned nsid, struct nvme_ns_ids *ids, bool is_shared)
 {
 	struct nvme_ns_head *head;
 	size_t size = sizeof(*head);
@@ -3810,6 +3810,7 @@ static struct nvme_ns_head *nvme_alloc_ns_head(struct nvme_ctrl *ctrl,
 	head->subsys = ctrl->subsys;
 	head->ns_id = nsid;
 	head->ids = *ids;
+	head->shared = is_shared;
 	kref_init(&head->ref);
 
 	if (head->ids.csi) {
@@ -3891,12 +3892,11 @@ static int nvme_init_ns_head(struct nvme_ns *ns, unsigned nsid,
 				nsid);
 			goto out_unlock;
 		}
-		head = nvme_alloc_ns_head(ctrl, nsid, ids);
+		head = nvme_alloc_ns_head(ctrl, nsid, ids, is_shared);
 		if (IS_ERR(head)) {
 			ret = PTR_ERR(head);
 			goto out_unlock;
 		}
-		head->shared = is_shared;
 	} else {
 		ret = -EINVAL;
 		if (!is_shared || !head->shared) {