nvme: cleanup namespace identifier reporting in nvme_init_ns_head

Lift the common namespace identifier reporting between the shared
namespace and new nshead cases into common code.  This also means
one less lock is held while doing I/O.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>

drivers/nvme/host/core.c

@@ -3390,7 +3390,8 @@ static int __nvme_check_ids(struct nvme_subsystem *subsys,
 }
 
 static struct nvme_ns_head *nvme_alloc_ns_head(struct nvme_ctrl *ctrl,
-		unsigned nsid, struct nvme_id_ns *id)
+		unsigned nsid, struct nvme_id_ns *id,
+		struct nvme_ns_ids *ids)
 {
 	struct nvme_ns_head *head;
 	size_t size = sizeof(*head);
@@ -3413,12 +3414,9 @@ static struct nvme_ns_head *nvme_alloc_ns_head(struct nvme_ctrl *ctrl,
 		goto out_ida_remove;
 	head->subsys = ctrl->subsys;
 	head->ns_id = nsid;
+	head->ids = *ids;
 	kref_init(&head->ref);
 
-	ret = nvme_report_ns_ids(ctrl, nsid, id, &head->ids);
-	if (ret)
-		goto out_cleanup_srcu;
-
 	ret = __nvme_check_ids(ctrl->subsys, head);
 	if (ret) {
 		dev_err(ctrl->device,
@@ -3453,24 +3451,23 @@ static int nvme_init_ns_head(struct nvme_ns *ns, unsigned nsid,
 	struct nvme_ctrl *ctrl = ns->ctrl;
 	bool is_shared = id->nmic & (1 << 0);
 	struct nvme_ns_head *head = NULL;
+	struct nvme_ns_ids ids;
 	int ret = 0;
 
+	ret = nvme_report_ns_ids(ctrl, nsid, id, &ids);
+	if (ret)
+		goto out;
+
 	mutex_lock(&ctrl->subsys->lock);
 	if (is_shared)
 		head = nvme_find_ns_head(ctrl->subsys, nsid);
 	if (!head) {
-		head = nvme_alloc_ns_head(ctrl, nsid, id);
+		head = nvme_alloc_ns_head(ctrl, nsid, id, &ids);
 		if (IS_ERR(head)) {
 			ret = PTR_ERR(head);
 			goto out_unlock;
 		}
 	} else {
-		struct nvme_ns_ids ids;
-
-		ret = nvme_report_ns_ids(ctrl, nsid, id, &ids);
-		if (ret)
-			goto out_unlock;
-
 		if (!nvme_ns_ids_equal(&head->ids, &ids)) {
 			dev_err(ctrl->device,
 				"IDs don't match for shared namespace %d\n",
@@ -3485,6 +3482,7 @@ static int nvme_init_ns_head(struct nvme_ns *ns, unsigned nsid,
 
 out_unlock:
 	mutex_unlock(&ctrl->subsys->lock);
+out:
 	if (ret > 0)
 		ret = blk_status_to_errno(nvme_error_status(ret));
 	return ret;