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>

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 744833b..5873e4a 100644 (file)
--- 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 9ef6640..a753df2 100644 (file)
--- 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 4afa4f8..1e1fa3f 100644 (file)
--- 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 306dd8c..0bdfd46 100644 (file)
--- 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);        \