nvme: check namespace head shared property

Reject a new shared namespace if a duplicate unshared namespace exists.
Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/host/core.c

@@ -3496,8 +3496,9 @@ static int nvme_init_ns_head(struct nvme_ns *ns, unsigned nsid,
 			ret = PTR_ERR(head);
 			goto out_unlock;
 		}
+		head->shared = is_shared;
 	} else {
-		if (!is_shared) {
+		if (!is_shared || !head->shared) {
 			dev_err(ctrl->device,
 				"Duplicate unshared namespace %d\n",
 					nsid);

drivers/nvme/host/nvme.h

@@ -352,6 +352,7 @@ struct nvme_ns_head {
 	struct nvme_ns_ids	ids;
 	struct list_head	entry;
 	struct kref		ref;
+	bool			shared;
 	int			instance;
 #ifdef CONFIG_NVME_MULTIPATH
 	struct gendisk		*disk;