From ce40426fdc3c92acdba6b5ca74bc7277ffaa6a3d Mon Sep 17 00:00:00 2001
From: Khazhismel Kumykov <khazhy@google.com>
Date: Mon, 11 Apr 2022 15:03:35 -0700
Subject: [PATCH] dm mpath: only use ktime_get_ns() in historical selector
Git-commit: ce40426fdc3c92acdba6b5ca74bc7277ffaa6a3d
Patch-mainline: v5.18-rc3
References: git-fixes

Mixing sched_clock() and ktime_get_ns() usage will give bad results.

Switch hst_select_path() from using sched_clock() to ktime_get_ns().
Also rename path_service_time()'s 'sched_now' variable to 'now'.

(Coly Li: rebased for Linux 5.14 based SUSE kernel)

Fixes: 2613eab11996 ("dm mpath: add Historical Service Time Path Selector")
Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Coly Li <colyli@suse.de>

---
 drivers/md/dm-ps-historical-service-time.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/drivers/md/dm-ps-historical-service-time.c
+++ b/drivers/md/dm-ps-historical-service-time.c
@@ -429,7 +429,7 @@ static struct dm_path *hst_select_path(s
 {
 	struct selector *s = ps->context;
 	struct path_info *pi = NULL, *best = NULL;
-	u64 time_now = sched_clock();
+	u64 time_now = ktime_get_ns();
 	struct dm_path *ret = NULL;
 	unsigned long flags;
 
@@ -470,7 +470,7 @@ static int hst_start_io(struct path_sele
 
 static u64 path_service_time(struct path_info *pi, u64 start_time)
 {
-	u64 sched_now = ktime_get_ns();
+	u64 now = ktime_get_ns();
 
 	/* if a previous disk request has finished after this IO was
 	 * sent to the hardware, pretend the submission happened
@@ -479,11 +479,11 @@ static u64 path_service_time(struct path
 	if (time_after64(pi->last_finish, start_time))
 		start_time = pi->last_finish;
 
-	pi->last_finish = sched_now;
-	if (time_before64(sched_now, start_time))
+	pi->last_finish = now;
+	if (time_before64(now, start_time))
 		return 0;
 
-	return sched_now - start_time;
+	return now - start_time;
 }
 
 static int hst_end_io(struct path_selector *ps, struct dm_path *path,