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mq-deadline: Introduce dispatch helpers 

Avoid directly referencing the next_rq and fifo_list arrays using the
helper functions deadline_next_request() and deadline_fifo_request() to
facilitate changes in the dispatch request selection in
__dd_dispatch_request() for zoned block devices.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Bart Van Assche <Bart.VanAssche@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Damien Le Moal 2017-12-21 15:43:39 +09:00 committed by Jens Axboe
parent 6cc77e9cb0
commit bf09ce56f0
1 changed files with 37 additions and 8 deletions
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45
block/mq-deadline.c
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@ -191,6 +191,35 @@ static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
return 0;
}
/*
* For the specified data direction, return the next request to
* dispatch using arrival ordered lists.
*/
static struct request *
deadline_fifo_request(struct deadline_data *dd, int data_dir)
{
if (WARN_ON_ONCE(data_dir != READ && data_dir != WRITE))
return NULL;
if (list_empty(&dd->fifo_list[data_dir]))
return NULL;
return rq_entry_fifo(dd->fifo_list[data_dir].next);
}
/*
* For the specified data direction, return the next request to
* dispatch using sector position sorted lists.
*/
static struct request *
deadline_next_request(struct deadline_data *dd, int data_dir)
{
if (WARN_ON_ONCE(data_dir != READ && data_dir != WRITE))
return NULL;
return dd->next_rq[data_dir];
}
/*
* deadline_dispatch_requests selects the best request according to
* read/write expire, fifo_batch, etc
@ -198,7 +227,7 @@ static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
static struct request *__dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
{
struct deadline_data *dd = hctx->queue->elevator->elevator_data;
struct request *rq;
struct request *rq, *next_rq;
bool reads, writes;
int data_dir;
@ -214,10 +243,9 @@ static struct request *__dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
/*
* batches are currently reads XOR writes
*/
if (dd->next_rq[WRITE])
rq = dd->next_rq[WRITE];
else
rq = dd->next_rq[READ];
rq = deadline_next_request(dd, WRITE);
if (!rq)
rq = deadline_next_request(dd, READ);
if (rq && dd->batching < dd->fifo_batch)
/* we have a next request are still entitled to batch */
@ -260,19 +288,20 @@ dispatch_find_request:
/*
* we are not running a batch, find best request for selected data_dir
*/
if (deadline_check_fifo(dd, data_dir) || !dd->next_rq[data_dir]) {
next_rq = deadline_next_request(dd, data_dir);
if (deadline_check_fifo(dd, data_dir) || !next_rq) {
/*
* A deadline has expired, the last request was in the other
* direction, or we have run out of higher-sectored requests.
* Start again from the request with the earliest expiry time.
*/
rq = rq_entry_fifo(dd->fifo_list[data_dir].next);
rq = deadline_fifo_request(dd, data_dir);
} else {
/*
* The last req was the same dir and we have a next request in
* sort order. No expired requests so continue on from here.
*/
rq = dd->next_rq[data_dir];
rq = next_rq;
}
dd->batching = 0;