[RFC PATCH v1 1/2] nvme: factor namespace-head queue-limit update

[Yao Sang]

Move the namespace head queue-limit update out of nvme_update_ns_info().
The new helper keeps the existing queue_limits_stack_bdev() based behavior
intact, including the current zoned resource handling, write-stream
assignment, integrity setup, capacity update, readonly update, and path
revalidation.

This is a preparatory refactor for replacing the generic stacked-device
limit update in the next patch.

Signed-off-by: Yao Sang <sangyao at kylinos.cn>
---
 drivers/nvme/host/core.c | 96 ++++++++++++++++++++++------------------
 1 file changed, 52 insertions(+), 44 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 453c1f0b2dd0..b96fa993a08f 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2517,6 +2517,56 @@ static void nvme_stack_zone_resources(struct queue_limits *t,
 		min_not_zero(t->max_active_zones, b->max_active_zones);
 }
 
+static int nvme_update_ns_head_limits(struct nvme_ns *ns,
+				      struct nvme_ns_info *info, bool unsupported)
+{
+	struct queue_limits *ns_lim = &ns->disk->queue->limits;
+	struct request_queue *head_q = ns->head->disk->queue;
+	struct queue_limits lim;
+	unsigned int memflags;
+	int ret;
+
+	lim = queue_limits_start_update(head_q);
+	memflags = blk_mq_freeze_queue(head_q);
+	/*
+	 * queue_limits mixes values that are the hardware limitations
+	 * for bio splitting with what is the device configuration.
+	 *
+	 * For NVMe the device configuration can change after e.g. a
+	 * Format command, and we really want to pick up the new format
+	 * value here. But we must still stack the queue limits to the
+	 * least common denominator for multipathing to split the bios
+	 * properly.
+	 *
+	 * To work around this, we explicitly set the device
+	 * configuration to those that we just queried, but only stack
+	 * the splitting limits in to make sure we still obey possibly
+	 * lower limitations of other controllers.
+	 */
+	lim.logical_block_size = ns_lim->logical_block_size;
+	lim.physical_block_size = ns_lim->physical_block_size;
+	lim.io_min = ns_lim->io_min;
+	lim.io_opt = ns_lim->io_opt;
+	queue_limits_stack_bdev(&lim, ns->disk->part0, 0,
+				ns->head->disk->disk_name);
+	if (lim.features & BLK_FEAT_ZONED)
+		nvme_stack_zone_resources(&lim, ns_lim);
+	if (unsupported)
+		ns->head->disk->flags |= GENHD_FL_HIDDEN;
+	else
+		nvme_init_integrity(ns->head, &lim, info);
+	lim.max_write_streams = ns_lim->max_write_streams;
+	lim.write_stream_granularity = ns_lim->write_stream_granularity;
+	ret = queue_limits_commit_update(head_q, &lim);
+
+	set_capacity_and_notify(ns->head->disk, get_capacity(ns->disk));
+	set_disk_ro(ns->head->disk, nvme_ns_is_readonly(ns, info));
+	nvme_mpath_revalidate_paths(ns->head);
+
+	blk_mq_unfreeze_queue(head_q, memflags);
+	return ret;
+}
+
 static int nvme_update_ns_info(struct nvme_ns *ns, struct nvme_ns_info *info)
 {
 	bool unsupported = false;
@@ -2555,50 +2605,8 @@ static int nvme_update_ns_info(struct nvme_ns *ns, struct nvme_ns_info *info)
 		ret = 0;
 	}
 
-	if (!ret && nvme_ns_head_multipath(ns->head)) {
-		struct queue_limits *ns_lim = &ns->disk->queue->limits;
-		struct queue_limits lim;
-		unsigned int memflags;
-
-		lim = queue_limits_start_update(ns->head->disk->queue);
-		memflags = blk_mq_freeze_queue(ns->head->disk->queue);
-		/*
-		 * queue_limits mixes values that are the hardware limitations
-		 * for bio splitting with what is the device configuration.
-		 *
-		 * For NVMe the device configuration can change after e.g. a
-		 * Format command, and we really want to pick up the new format
-		 * value here.  But we must still stack the queue limits to the
-		 * least common denominator for multipathing to split the bios
-		 * properly.
-		 *
-		 * To work around this, we explicitly set the device
-		 * configuration to those that we just queried, but only stack
-		 * the splitting limits in to make sure we still obey possibly
-		 * lower limitations of other controllers.
-		 */
-		lim.logical_block_size = ns_lim->logical_block_size;
-		lim.physical_block_size = ns_lim->physical_block_size;
-		lim.io_min = ns_lim->io_min;
-		lim.io_opt = ns_lim->io_opt;
-		queue_limits_stack_bdev(&lim, ns->disk->part0, 0,
-					ns->head->disk->disk_name);
-		if (lim.features & BLK_FEAT_ZONED)
-			nvme_stack_zone_resources(&lim, ns_lim);
-		if (unsupported)
-			ns->head->disk->flags |= GENHD_FL_HIDDEN;
-		else
-			nvme_init_integrity(ns->head, &lim, info);
-		lim.max_write_streams = ns_lim->max_write_streams;
-		lim.write_stream_granularity = ns_lim->write_stream_granularity;
-		ret = queue_limits_commit_update(ns->head->disk->queue, &lim);
-
-		set_capacity_and_notify(ns->head->disk, get_capacity(ns->disk));
-		set_disk_ro(ns->head->disk, nvme_ns_is_readonly(ns, info));
-		nvme_mpath_revalidate_paths(ns->head);
-
-		blk_mq_unfreeze_queue(ns->head->disk->queue, memflags);
-	}
+	if (!ret && nvme_ns_head_multipath(ns->head))
+		ret = nvme_update_ns_head_limits(ns, info, unsupported);
 
 	return ret;
 }
-- 
2.25.1