[PATCH v2] block: Use div64_ul instead of do_div

[cgel . zte]

From: Changcheng Deng <deng.changcheng@xxxxxxxxxx>

do_div() does a 64-by-32 division. Here the divisor is an unsigned long
which on some platforms is 64 bit wide. So use div64_ul instead of do_div
to avoid a possible truncation.

Reported-by: Zeal Robot <zealci@xxxxxxxxxx>
Signed-off-by: Changcheng Deng <deng.changcheng@xxxxxxxxxx>
---
 block/blk-throttle.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 39bb6e68a9a2..2db635d66617 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1903,7 +1903,7 @@ static void throtl_downgrade_check(struct throtl_grp *tg)
 
 	if (tg->bps[READ][LIMIT_LOW]) {
 		bps = tg->last_bytes_disp[READ] * HZ;
-		do_div(bps, elapsed_time);
+		bps = div64_ul(bps, elapsed_time);
 		if (bps >= tg->bps[READ][LIMIT_LOW])
 			tg->last_low_overflow_time[READ] = now;
 	}
-- 
2.25.1