+static struct nvme_ns_head *__nvme_find_ns_head(struct nvme_subsystem *subsys,
+ unsigned nsid)
+{
+ struct nvme_ns_head *h;
+
+ lockdep_assert_held(&subsys->lock);
+
+ list_for_each_entry(h, &subsys->nsheads, entry) {
+ if (h->ns_id == nsid && kref_get_unless_zero(&h->ref))
+ return h;
+ }
+
+ return NULL;
+}
+
+static int __nvme_check_ids(struct nvme_subsystem *subsys,
+ struct nvme_ns_head *new)
+{
+ struct nvme_ns_head *h;
+
+ lockdep_assert_held(&subsys->lock);
+
+ list_for_each_entry(h, &subsys->nsheads, entry) {
+ if (nvme_ns_ids_valid(&new->ids) &&
+ nvme_ns_ids_equal(&new->ids, &h->ids))
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static struct nvme_ns_head *nvme_alloc_ns_head(struct nvme_ctrl *ctrl,
+ unsigned nsid, struct nvme_id_ns *id)
+{
+ struct nvme_ns_head *head;
+ int ret = -ENOMEM;
+
+ head = kzalloc(sizeof(*head), GFP_KERNEL);
+ if (!head)
+ goto out;
+ ret = ida_simple_get(&ctrl->subsys->ns_ida, 1, 0, GFP_KERNEL);
+ if (ret < 0)
+ goto out_free_head;
+ head->instance = ret;
+ INIT_LIST_HEAD(&head->list);
+ init_srcu_struct(&head->srcu);
+ head->subsys = ctrl->subsys;
+ head->ns_id = nsid;
+ kref_init(&head->ref);
+
+ nvme_report_ns_ids(ctrl, nsid, id, &head->ids);
+
+ ret = __nvme_check_ids(ctrl->subsys, head);
+ if (ret) {
+ dev_err(ctrl->device,
+ "duplicate IDs for nsid %d\n", nsid);
+ goto out_cleanup_srcu;
+ }
+
+ list_add_tail(&head->entry, &ctrl->subsys->nsheads);
+ return head;
+out_cleanup_srcu:
+ cleanup_srcu_struct(&head->srcu);
+ ida_simple_remove(&ctrl->subsys->ns_ida, head->instance);
+out_free_head:
+ kfree(head);
+out:
+ return ERR_PTR(ret);
+}
+
+static int nvme_init_ns_head(struct nvme_ns *ns, unsigned nsid,
+ struct nvme_id_ns *id, bool *new)
+{
+ struct nvme_ctrl *ctrl = ns->ctrl;
+ bool is_shared = id->nmic & (1 << 0);
+ struct nvme_ns_head *head = NULL;
+ int ret = 0;
+
+ 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);
+ if (IS_ERR(head)) {
+ ret = PTR_ERR(head);
+ goto out_unlock;
+ }
+
+ *new = true;
+ } else {
+ struct nvme_ns_ids ids;
+
+ nvme_report_ns_ids(ctrl, nsid, id, &ids);
+ if (!nvme_ns_ids_equal(&head->ids, &ids)) {
+ dev_err(ctrl->device,
+ "IDs don't match for shared namespace %d\n",
+ nsid);
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ *new = false;
+ }
+
+ list_add_tail(&ns->siblings, &head->list);
+ ns->head = head;
+
+out_unlock:
+ mutex_unlock(&ctrl->subsys->lock);
+ return ret;
+}
+