[PATCH 5.17 121/219] dm mpath: only use ktime_get_ns() in historical selector

Greg Kroah-Hartman
2022-04-18T12:27:38Z

From: Khazhismel Kumykov <khazhy@google.com>

[ Upstream commit ce40426fdc3c92acdba6b5ca74bc7277ffaa6a3d ]

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'.

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: Sasha Levin <sashal@kernel.org>
---
drivers/md/dm-ps-historical-service-time.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/md/dm-ps-historical-service-time.c b/drivers/md/dm-ps-historical-service-time.c
index 875bca30a0dd..82f2a06153dc 100644
--- a/drivers/md/dm-ps-historical-service-time.c
+++ b/drivers/md/dm-ps-historical-service-time.c
@@ -27,7 +27,6 @@
#include <linux/blkdev.h>
#include <linux/slab.h>
#include <linux/module.h>
-#include <linux/sched/clock.h>

#define DM_MSG_PREFIX "multipath historical-service-time"
@@ -433,7 +432,7 @@ static struct dm_path *hst_select_path(struct path_selector *ps,
{
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;

@@ -474,7 +473,7 @@ static int hst_start_io(struct path_selector *ps, struct dm_path *path,

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
@@ -483,11 +482,11 @@ static u64 path_service_time(struct path_info *pi, u64 start_time)
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,
--
2.35.1