From: Christoph Hellwig <hch@lst.de>
Date: Mon, 28 Sep 2020 12:34:04 +0200
Subject: nvme: call nvme_identify_ns as the first thing in nvme_alloc_ns_block
Patch-mainline: v5.10-rc1
Git-commit: fab72f5a046883ae5851c95b7c6e7a08f984e391
References: bsc#1180197

Check if the namespace actually exists as the very first thing and don't
bother with any extra work if not.  This should speed up and simplify
the sequential scanning for NVMe 1.0 devices.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Acked-by: Daniel Wagner <dwagner@suse.de>
---
 drivers/nvme/host/core.c |   15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3909,9 +3909,12 @@ static void nvme_alloc_ns(struct nvme_ct
 	char disk_name[DISK_NAME_LEN];
 	int node = ctrl->numa_node, flags = GENHD_FL_EXT_DEVT, ret;
 
+	if (nvme_identify_ns(ctrl, nsid, &id))
+		return;
+
 	ns = kzalloc_node(sizeof(*ns), GFP_KERNEL, node);
 	if (!ns)
-		return;
+		goto out_free_id;
 
 	ns->queue = blk_mq_init_queue(ctrl->tagset);
 	if (IS_ERR(ns->queue))
@@ -3934,13 +3937,9 @@ static void nvme_alloc_ns(struct nvme_ct
 	blk_queue_logical_block_size(ns->queue, 1 << ns->lba_shift);
 	nvme_set_queue_limits(ctrl, ns->queue);
 
-	ret = nvme_identify_ns(ctrl, nsid, &id);
-	if (ret)
-		goto out_free_queue;
-
 	ret = nvme_init_ns_head(ns, nsid, id);
 	if (ret)
-		goto out_free_id;
+		goto out_free_queue;
 	nvme_set_disk_name(disk_name, ns, ctrl, &flags);
 
 	disk = alloc_disk_node(0, node);
@@ -3991,12 +3990,12 @@ static void nvme_alloc_ns(struct nvme_ct
 		list_del_init(&ns->head->entry);
 	mutex_unlock(&ctrl->subsys->lock);
 	nvme_put_ns_head(ns->head);
- out_free_id:
-	kfree(id);
  out_free_queue:
 	blk_cleanup_queue(ns->queue);
  out_free_ns:
 	kfree(ns);
+ out_free_id:
+	kfree(id);
 }
 
 static void nvme_ns_remove(struct nvme_ns *ns)