block: Stop abusing csd.list for fifo_time

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>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

4 files changed, 9 insertions, 14 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 744833b630c6..5873e4ada9eb 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -2367,10 +2367,10 @@ 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)
@@ -2814,7 +2814,7 @@ 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);
@@ -3927,7 +3927,7 @@ 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 4afa4f8f6090..1e1fa3f93d5f 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -99,6 +99,7 @@ struct request {
         union {
                 struct call_single_data csd;
                 struct work_struct mq_flush_work;
+                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);        \