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cfq-iosched: simplify control flow in cfq_get_queue()

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cfq_get_queue()'s control flow looks like the following.

	async_cfqq = NULL;
	cfqq = NULL;

	if (!is_sync) {
		...
		async_cfqq = ...;
		cfqq = *async_cfqq;
	}

	if (!cfqq)
		cfqq = ...;

	if (!is_sync && !(*async_cfqq))
		...;

The only thing the local variable init, the second if, and the
async_cfqq test in the third if achieves is to skip cfqq creation and
installation if *async_cfqq was already non-NULL.  This is needlessly
complicated with different tests examining the same condition.
Simplify it to the following.

	if (!is_sync) {
		...
		async_cfqq = ...;
		cfqq = *async_cfqq;
		if (cfqq)
			goto out;
	}

	cfqq = ...;

	if (!is_sync)
		...;
 out:

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Tejun Heo 2015-08-18 14:54:57 -07:00 committed by Jens Axboe
parent 5634cc2aa9
commit 4ebc1c61d6
1 changed files with 7 additions and 6 deletions
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13
block/cfq-iosched.c
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@ -3731,8 +3731,8 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
{
int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
struct cfq_queue **async_cfqq = NULL;
struct cfq_queue *cfqq = NULL;
struct cfq_queue **async_cfqq;
struct cfq_queue *cfqq;
if (!is_sync) {
if (!ioprio_valid(cic->ioprio)) {
@ -3742,19 +3742,20 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
}
async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
cfqq = *async_cfqq;
if (cfqq)
goto out;
}
if (!cfqq)
cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, bio, gfp_mask);
cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, bio, gfp_mask);
/*
* pin the queue now that it's allocated, scheduler exit will prune it
*/
if (!is_sync && !(*async_cfqq)) {
if (!is_sync) {
cfqq->ref++;
*async_cfqq = cfqq;
}
out:
cfqq->ref++;
return cfqq;
}