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block, bfq: improve arithmetic division in bfq_delta()

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do_div() does a 64-by-32 division. Use div64_ul() instead of it
if the divisor is unsigned long, to avoid truncation to 32-bit.
And as a nice side effect also cleans up the function a bit.

Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
Cc: Paolo Valente <paolo.valente@linaro.org>
Cc: Jens Axboe <axboe@fb.com>
Cc: linux-block@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Wen Yang 2020-01-20 18:04:43 +08:00 committed by Jens Axboe
parent b7f22d993f
commit 554d21efb0
1 changed files with 1 additions and 4 deletions
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5
block/bfq-wf2q.c
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@ -277,10 +277,7 @@ struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity)
*/
static u64 bfq_delta(unsigned long service, unsigned long weight)
{
u64 d = (u64)service << WFQ_SERVICE_SHIFT;
do_div(d, weight);
return d;
return div64_ul((u64)service << WFQ_SERVICE_SHIFT, weight);
}
/**