[PATCH 6/6] nvme: track shared namespaces in a siblings list

[Christoph Hellwig]

Verify that our IDs match for shared namespaces in a subystem, and link
them up in a headless queue so that we can find siblings easily.

Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 drivers/nvme/host/core.c | 99 ++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/nvme/host/nvme.h |  1 +
 2 files changed, 100 insertions(+)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index d88cd6a4a549..8a44d68a3f98 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2261,6 +2261,100 @@ static struct nvme_ns *nvme_find_get_ns(struct nvme_ctrl *ctrl, unsigned nsid)
 	return ret;
 }
 
+/*
+ * Check if the two nvme_ns structures refer to the same namespace.
+ *
+ * Returns 1 if they refer to the same namespace, 0 if not, or a negative
+ * errno value on error.
+ */
+static int nvme_ns_compare_ids(struct nvme_ns *ns, struct nvme_id_ns *id,
+		struct nvme_ns *cur)
+{
+	bool is_shared = id->nmic & (1 << 0);
+	bool have_id = false;
+
+	if (!uuid_is_null(&ns->uuid)) {
+		have_id = true;
+		if (!uuid_equal(&ns->uuid, &cur->uuid))
+			return 0;
+	}
+	if (memchr_inv(ns->nguid, 0, sizeof(ns->nguid))) {
+		have_id = true;
+		if (memcmp(&ns->nguid, &cur->nguid, sizeof(ns->nguid)))
+			return 0;
+	}
+	if (memchr_inv(ns->eui, 0, sizeof(ns->eui))) {
+		have_id = true;
+		if (memcmp(&ns->eui, &cur->eui, sizeof(ns->eui)))
+			return 0;
+	}
+
+	/*
+	 * Note that the unique identifiers are only a "should" condition in
+	 * the specification.  But we require them for multipath operations
+	 * due to safety concerns.
+	 */
+	if (!have_id && is_shared) {
+		dev_err(ns->ctrl->device,
+			"shared namespace %u without unique ID.\n",
+			ns->ns_id);
+		return -EINVAL;
+	}
+
+	if (have_id && !is_shared) {
+		dev_err(ns->ctrl->device,
+			"private namespace %u with duplicate ID.\n",
+			ns->ns_id);
+		return -EINVAL;
+	}
+
+	/*
+	 * As of NVMe 1.3 (Section 6.1) this is only strictly required if namespace
+	 * management is supported, but sort of implied for shared namespaces
+	 * by omitting the defintion.  We'll need an ECN for this language
+	 * eventually.
+	 */
+	if (is_shared && ns->ns_id != cur->ns_id) {
+		dev_err(ns->ctrl->device,
+			"non-matching nsids (%u vs %u) for shared namespaces\n",
+			ns->ns_id, cur->ns_id);
+		return -EINVAL;
+	}
+
+	return 1;
+}
+
+static int nvme_ns_find_siblings(struct nvme_ns *ns, struct nvme_id_ns *id)
+{
+	struct nvme_subsystem *subsys = ns->ctrl->subsys;
+	struct nvme_ctrl *ctrl;
+	struct nvme_ns *cur;
+	int err = 0, ret;
+
+	mutex_lock(&subsys->lock);
+	list_for_each_entry(ctrl, &subsys->ctrls, subsys_entry) {
+		if (ctrl == ns->ctrl)
+			continue;
+
+		mutex_lock(&ctrl->namespaces_mutex);
+		list_for_each_entry(cur, &ctrl->namespaces, list) {
+			ret = nvme_ns_compare_ids(ns, id, cur);
+			if (ret < 0) {
+				err = ret;
+				break;
+			}
+			if (ret > 0)
+				list_add(&ns->siblings, &cur->siblings);
+		}
+		mutex_unlock(&ctrl->namespaces_mutex);
+
+		if (err)
+			break;
+	}
+	mutex_unlock(&subsys->lock);
+	return err;
+}
+
 static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid)
 {
 	struct nvme_ns *ns;
@@ -2283,6 +2377,7 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid)
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, ns->queue);
 	ns->queue->queuedata = ns;
 	ns->ctrl = ctrl;
+	INIT_LIST_HEAD(&ns->siblings);
 
 	kref_init(&ns->kref);
 	ns->ns_id = nsid;
@@ -2296,6 +2391,9 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid)
 	if (nvme_revalidate_ns(ns, &id))
 		goto out_free_queue;
 
+	if (nvme_ns_find_siblings(ns, id))
+		goto out_free_id;
+
 	if (nvme_nvm_ns_supported(ns, id) &&
 				nvme_nvm_register(ns, disk_name, node)) {
 		dev_warn(ctrl->device, "%s: LightNVM init failure\n", __func__);
@@ -2360,6 +2458,7 @@ static void nvme_ns_remove(struct nvme_ns *ns)
 
 	mutex_lock(&ns->ctrl->namespaces_mutex);
 	list_del_init(&ns->list);
+	list_del_init(&ns->siblings);
 	mutex_unlock(&ns->ctrl->namespaces_mutex);
 
 	nvme_put_ns(ns);
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index fe0d4ec32207..ab147b76cf28 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -196,6 +196,7 @@ struct nvme_ns {
 	struct nvme_ctrl *ctrl;
 	struct request_queue *queue;
 	struct gendisk *disk;
+	struct list_head siblings;
 	struct nvm_dev *ndev;
 	struct kref kref;
 	int instance;
-- 
2.11.0