From: Aleksei Zakharov <zakharov.a.g@yandex.ru>
Date: Mon, 11 Feb 2019 10:10:34 +0000 (+0300)
Subject: block: avoid setting wbt_lat_usec to current value
X-Git-Tag: v5.1-rc1~100^2~42
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=b7143fe67bfc3b83a9e11371da659e1e70a1bbf3;p=linux.git

block: avoid setting wbt_lat_usec to current value

There's no reason to set wbt min lat and freeze request queue
if current value is the same.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Aleksei Zakharov <zakharov.a.g@yandex.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 94e1b052abbc..59685918167e 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -468,6 +468,9 @@ static ssize_t queue_wb_lat_store(struct request_queue *q, const char *page,
 	else if (val >= 0)
 		val *= 1000ULL;
 
+	if (wbt_get_min_lat(q) == val)
+		return count;
+
 	/*
 	 * Ensure that the queue is idled, in case the latency update
 	 * ends up either enabling or disabling wbt completely. We can't