[PATCH 1/9] block: Stop abusing csd.list for fifo_time

Jan Kara
2013-12-23T20:42:37Z

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.

Signed-off-by: Jan Kara <jack@suse.cz>
---
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