From ed1e0252111b0616f8bb6fef0ee0f5345c534301 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Tue, 14 Sep 2021 08:38:20 +0200
Subject: [PATCH] nvme: keep ctrl->namespaces ordered
Git-commit: 298ba0e3d4af539cc37f982d4c011a0f07fca48c
Patch-mainline: v5.15-rc3
References: stable-5.14.9

[ Upstream commit 298ba0e3d4af539cc37f982d4c011a0f07fca48c ]

Various places in the nvme code that rely on ctrl->namespace to be
ordered.  Ensure that the namespae is inserted into the list at the
right position from the start instead of sorting it after the fact.

Fixes: 540c801c65eb ("NVMe: Implement namespace list scanning")
Reported-by: Anton Eidelman <anton.eidelman@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/nvme/host/core.c |   33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -13,7 +13,6 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/backing-dev.h>
-#include <linux/list_sort.h>
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/pr.h>
@@ -3722,15 +3721,6 @@ out_unlock:
 	return ret;
 }
 
-static int ns_cmp(void *priv, const struct list_head *a,
-		const struct list_head *b)
-{
-	struct nvme_ns *nsa = container_of(a, struct nvme_ns, list);
-	struct nvme_ns *nsb = container_of(b, struct nvme_ns, list);
-
-	return nsa->head->ns_id - nsb->head->ns_id;
-}
-
 struct nvme_ns *nvme_find_get_ns(struct nvme_ctrl *ctrl, unsigned nsid)
 {
 	struct nvme_ns *ns, *ret = NULL;
@@ -3751,6 +3741,22 @@ struct nvme_ns *nvme_find_get_ns(struct
 }
 EXPORT_SYMBOL_NS_GPL(nvme_find_get_ns, NVME_TARGET_PASSTHRU);
 
+/*
+ * Add the namespace to the controller list while keeping the list ordered.
+ */
+static void nvme_ns_add_to_ctrl_list(struct nvme_ns *ns)
+{
+	struct nvme_ns *tmp;
+
+	list_for_each_entry_reverse(tmp, &ns->ctrl->namespaces, list) {
+		if (tmp->head->ns_id < ns->head->ns_id) {
+			list_add(&ns->list, &tmp->list);
+			return;
+		}
+	}
+	list_add(&ns->list, &ns->ctrl->namespaces);
+}
+
 static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid,
 		struct nvme_ns_ids *ids)
 {
@@ -3801,9 +3807,8 @@ static void nvme_alloc_ns(struct nvme_ct
 		goto out_unlink_ns;
 
 	down_write(&ctrl->namespaces_rwsem);
-	list_add_tail(&ns->list, &ctrl->namespaces);
+	nvme_ns_add_to_ctrl_list(ns);
 	up_write(&ctrl->namespaces_rwsem);
-
 	nvme_get_ctrl(ctrl);
 
 	device_add_disk(ctrl->device, ns->disk, nvme_ns_id_attr_groups);
@@ -4083,10 +4088,6 @@ static void nvme_scan_work(struct work_s
 	if (nvme_scan_ns_list(ctrl) != 0)
 		nvme_scan_ns_sequential(ctrl);
 	mutex_unlock(&ctrl->scan_lock);
-
-	down_write(&ctrl->namespaces_rwsem);
-	list_sort(NULL, &ctrl->namespaces, ns_cmp);
-	up_write(&ctrl->namespaces_rwsem);
 }
 
 /*