On Wed 18-12-13 18:23:33, Jan Kara wrote:
> Block layer currently abuses rq->csd.list.next for storing fifo_time.
> That is a terrible hack and completely unnecessary as well. Union
> achieves the same space saving in a cleaner way.
This is the correct patch 1/3.
Honza
>
> Signed-off-by: Jan Kara <[email protected]>
> ---
> block/cfq-iosched.c | 8 ++++----
> block/deadline-iosched.c | 8 ++++----
> include/linux/blkdev.h | 1 +
> include/linux/elevator.h | 6 ------
> 4 files changed, 9 insertions(+), 14 deletions(-)
>
> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
> index 4d5cec1ad80d..37ea6045fdc6 100644
> --- a/block/cfq-iosched.c
> +++ b/block/cfq-iosched.c
> @@ -2382,10 +2382,10 @@ cfq_merged_requests(struct request_queue *q, struct
> request *rq,
> * reposition in fifo if next is older than rq
> */
> if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
> - time_before(rq_fifo_time(next), rq_fifo_time(rq)) &&
> + time_before(next->fifo_time, rq->fifo_time) &&
> cfqq == RQ_CFQQ(next)) {
> list_move(&rq->queuelist, &next->queuelist);
> - rq_set_fifo_time(rq, rq_fifo_time(next));
> + rq->fifo_time = next->fifo_time;
> }
>
> if (cfqq->next_rq == next)
> @@ -2829,7 +2829,7 @@ static struct request *cfq_check_fifo(struct cfq_queue
> *cfqq)
> return NULL;
>
> rq = rq_entry_fifo(cfqq->fifo.next);
> - if (time_before(jiffies, rq_fifo_time(rq)))
> + if (time_before(jiffies, rq->fifo_time))
> rq = NULL;
>
> cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
> @@ -3942,7 +3942,7 @@ static void cfq_insert_request(struct request_queue *q,
> struct request *rq)
> cfq_log_cfqq(cfqd, cfqq, "insert_request");
> cfq_init_prio_data(cfqq, RQ_CIC(rq));
>
> - rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
> + rq->fifo_time = jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)];
> list_add_tail(&rq->queuelist, &cfqq->fifo);
> cfq_add_rq_rb(rq);
> cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group,
> diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
> index 9ef66406c625..a753df2b3fc2 100644
> --- a/block/deadline-iosched.c
> +++ b/block/deadline-iosched.c
> @@ -106,7 +106,7 @@ deadline_add_request(struct request_queue *q, struct
> request *rq)
> /*
> * set expire time and add to fifo list
> */
> - rq_set_fifo_time(rq, jiffies + dd->fifo_expire[data_dir]);
> + rq->fifo_time = jiffies + dd->fifo_expire[data_dir];
> list_add_tail(&rq->queuelist, &dd->fifo_list[data_dir]);
> }
>
> @@ -174,9 +174,9 @@ deadline_merged_requests(struct request_queue *q, struct
> request *req,
> * and move into next position (next will be deleted) in fifo
> */
> if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
> - if (time_before(rq_fifo_time(next), rq_fifo_time(req))) {
> + if (time_before(next->fifo_time, req->fifo_time)) {
> list_move(&req->queuelist, &next->queuelist);
> - rq_set_fifo_time(req, rq_fifo_time(next));
> + req->fifo_time = next->fifo_time;
> }
> }
>
> @@ -230,7 +230,7 @@ static inline int deadline_check_fifo(struct
> deadline_data *dd, int ddir)
> /*
> * rq is expired!
> */
> - if (time_after_eq(jiffies, rq_fifo_time(rq)))
> + if (time_after_eq(jiffies, rq->fifo_time))
> return 1;
>
> return 0;
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 1b135d49b279..744b5fb13a9b 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -102,6 +102,7 @@ struct request {
> union {
> struct call_single_data csd;
> struct work_struct mq_flush_data;
> + unsigned long fifo_time;
> };
>
> struct request_queue *q;
> diff --git a/include/linux/elevator.h b/include/linux/elevator.h
> index 306dd8cd0b6f..0bdfd46f4735 100644
> --- a/include/linux/elevator.h
> +++ b/include/linux/elevator.h
> @@ -202,12 +202,6 @@ enum {
> #define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
> #define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
>
> -/*
> - * Hack to reuse the csd.list list_head as the fifo time holder while
> - * the request is in the io scheduler. Saves an unsigned long in rq.
> - */
> -#define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next)
> -#define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp))
> #define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
> #define rq_fifo_clear(rq) do { \
> list_del_init(&(rq)->queuelist); \
> --
> 1.8.1.4
>
--
Jan Kara <[email protected]>
SUSE Labs, CR
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