[PATCH V2] nvme: report capacity 0 for non supported ZNS SSDs

["Javier González" <javier@javigon.com>]

Allow ZNS SSDs to be presented to the host even when they implement
features that are not supported by the kernel zoned block device.

Instead of rejecting the SSD at the NVMe driver level, deal with this in
the block layer by setting capacity to 0, as we do with other things
such as unsupported PI configurations. This allows to use standard
management tools such as nvme-cli to choose a different format or
firmware slot that is compatible with the Linux zoned block device.

Changes since V1:
   - Apply feedback from Niklas:
	- Use IS_ENABLED() for checking config option
	- Use local variable
	- Use different variable names

Signed-off-by: Javier González <javier.gonz@samsung.com>
---
 drivers/nvme/host/core.c |  3 +++
 drivers/nvme/host/nvme.h |  1 +
 drivers/nvme/host/zns.c  | 26 ++++++++++++++------------
 3 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index c190c56bf702..638997b6f5cd 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2026,6 +2026,9 @@ static void nvme_update_disk_info(struct gendisk *disk,
 			capacity = 0;
 	}
 
+	if (IS_ENABLED(CONFIG_BLK_DEV_ZONED) && !ns->zoned_ns_supp)
+		capacity = 0;
+
 	set_capacity_revalidate_and_notify(disk, capacity, false);
 
 	nvme_config_discard(disk, ns);
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 87737fa32360..ff4fe645ab9b 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -443,6 +443,7 @@ struct nvme_ns {
 	u8 pi_type;
 #ifdef CONFIG_BLK_DEV_ZONED
 	u64 zsze;
+	bool zoned_ns_supp;
 #endif
 	unsigned long features;
 	unsigned long flags;
diff --git a/drivers/nvme/host/zns.c b/drivers/nvme/host/zns.c
index 57cfd78731fb..1ae039f9c20c 100644
--- a/drivers/nvme/host/zns.c
+++ b/drivers/nvme/host/zns.c
@@ -42,22 +42,25 @@ int nvme_update_zone_info(struct gendisk *disk, struct nvme_ns *ns,
 	struct request_queue *q = disk->queue;
 	struct nvme_command c = { };
 	struct nvme_id_ns_zns *id;
+	bool zoned_ns_supp = true;
 	int status;
 
 	/* Driver requires zone append support */
 	if (!(le32_to_cpu(log->iocs[nvme_cmd_zone_append]) &
 			NVME_CMD_EFFECTS_CSUPP)) {
+		zoned_ns_supp = false;
 		dev_warn(ns->ctrl->device,
 			"append not supported for zoned namespace:%d\n",
 			ns->head->ns_id);
-		return -EINVAL;
-	}
-
-	/* Lazily query controller append limit for the first zoned namespace */
-	if (!ns->ctrl->max_zone_append) {
-		status = nvme_set_max_append(ns->ctrl);
-		if (status)
-			return status;
+	} else {
+		/* Lazily query controller append limit for the first
+		 * zoned namespace
+		 */
+		if (!ns->ctrl->max_zone_append) {
+			status = nvme_set_max_append(ns->ctrl);
+			if (status)
+				return status;
+		}
 	}
 
 	id = kzalloc(sizeof(*id), GFP_KERNEL);
@@ -78,23 +81,22 @@ int nvme_update_zone_info(struct gendisk *disk, struct nvme_ns *ns,
 	 * operation characteristics.
 	 */
 	if (id->zoc) {
+		zoned_ns_supp = false;
 		dev_warn(ns->ctrl->device,
 			"zone operations:%x not supported for namespace:%u\n",
 			le16_to_cpu(id->zoc), ns->head->ns_id);
-		status = -EINVAL;
-		goto free_data;
 	}
 
 	ns->zsze = nvme_lba_to_sect(ns, le64_to_cpu(id->lbafe[lbaf].zsze));
 	if (!is_power_of_2(ns->zsze)) {
+		zoned_ns_supp = false;
 		dev_warn(ns->ctrl->device,
 			"invalid zone size:%llu for namespace:%u\n",
 			ns->zsze, ns->head->ns_id);
-		status = -EINVAL;
-		goto free_data;
 	}
 
 	q->limits.zoned = BLK_ZONED_HM;
+	ns->zoned_ns_supp = zoned_ns_supp;
 	blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, q);
 	blk_queue_max_open_zones(q, le32_to_cpu(id->mor) + 1);
 	blk_queue_max_active_zones(q, le32_to_cpu(id->mar) + 1);
-- 
2.17.1