block, cfq: move cfqd->icq_list to request_queue and add request->elv.icq

Most of icq management is about to be moved out of cfq into blk-ioc.
This patch prepares for it.

* Move cfqd->icq_list to request_queue->icq_list

* Make request explicitly point to icq instead of through elevator
  private data.  ->elevator_private[3] is replaced with sub struct elv
  which contains icq pointer and priv[2].  cfq is updated accordingly.

* Meaningless clearing of ->elevator_private[0] removed from
  elv_set_request().  At that point in code, the field was guaranteed
  to be %NULL anyway.

This patch doesn't introduce any functional change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-core.c b/block/blk-core.c
index 6804fdf..3c26c7f 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -497,6 +497,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
                    laptop_mode_timer_fn, (unsigned long) q);
        setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
        INIT_LIST_HEAD(&q->timeout_list);
+       INIT_LIST_HEAD(&q->icq_list);
        INIT_LIST_HEAD(&q->flush_queue[0]);
        INIT_LIST_HEAD(&q->flush_queue[1]);
        INIT_LIST_HEAD(&q->flush_data_in_flight);

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index d2f16fc..9bc5ecc 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -54,9 +54,9 @@ static const int cfq_hist_divisor = 4;
 #define CFQQ_SECT_THR_NONROT   (sector_t)(2 * 32)
 #define CFQQ_SEEKY(cfqq)       (hweight32(cfqq->seek_history) > 32/8)
 
-#define RQ_CIC(rq)             icq_to_cic((rq)->elevator_private[0])
-#define RQ_CFQQ(rq)            (struct cfq_queue *) ((rq)->elevator_private[1])
-#define RQ_CFQG(rq)            (struct cfq_group *) ((rq)->elevator_private[2])
+#define RQ_CIC(rq)             icq_to_cic((rq)->elv.icq)
+#define RQ_CFQQ(rq)            (struct cfq_queue *) ((rq)->elv.priv[0])
+#define RQ_CFQG(rq)            (struct cfq_group *) ((rq)->elv.priv[1])
 
 static struct kmem_cache *cfq_pool;
 static struct kmem_cache *cfq_icq_pool;
@@ -297,8 +297,6 @@ struct cfq_data {
        unsigned int cfq_group_idle;
        unsigned int cfq_latency;
 
-       struct list_head icq_list;
-
        /*
         * Fallback dummy cfqq for extreme OOM conditions
         */
@@ -3053,7 +3051,7 @@ static int cfq_create_cic(struct cfq_data *cfqd, gfp_t gfp_mask)
        ret = radix_tree_insert(&ioc->icq_tree, q->id, icq);
        if (likely(!ret)) {
                hlist_add_head(&icq->ioc_node, &ioc->icq_list);
-               list_add(&icq->q_node, &cfqd->icq_list);
+               list_add(&icq->q_node, &q->icq_list);
                icq = NULL;
        } else if (ret == -EEXIST) {
                /* someone else already did it */
@@ -3605,12 +3603,10 @@ static void cfq_put_request(struct request *rq)
 
                put_io_context(RQ_CIC(rq)->icq.ioc, cfqq->cfqd->queue);
 
-               rq->elevator_private[0] = NULL;
-               rq->elevator_private[1] = NULL;
-
                /* Put down rq reference on cfqg */
                cfq_put_cfqg(RQ_CFQG(rq));
-               rq->elevator_private[2] = NULL;
+               rq->elv.priv[0] = NULL;
+               rq->elv.priv[1] = NULL;
 
                cfq_put_queue(cfqq);
        }
@@ -3696,9 +3692,9 @@ new_queue:
        cfqq->allocated[rw]++;
 
        cfqq->ref++;
-       rq->elevator_private[0] = &cic->icq;
-       rq->elevator_private[1] = cfqq;
-       rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg);
+       rq->elv.icq = &cic->icq;
+       rq->elv.priv[0] = cfqq;
+       rq->elv.priv[1] = cfq_ref_get_cfqg(cfqq->cfqg);
        spin_unlock_irq(q->queue_lock);
        return 0;
 
@@ -3810,8 +3806,8 @@ static void cfq_exit_queue(struct elevator_queue *e)
        if (cfqd->active_queue)
                __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
 
-       while (!list_empty(&cfqd->icq_list)) {
-               struct io_cq *icq = list_entry(cfqd->icq_list.next,
+       while (!list_empty(&q->icq_list)) {
+               struct io_cq *icq = list_entry(q->icq_list.next,
                                               struct io_cq, q_node);
                struct io_context *ioc = icq->ioc;
 
@@ -3922,8 +3918,6 @@ static void *cfq_init_queue(struct request_queue *q)
        cfqd->oom_cfqq.ref++;
        cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
 
-       INIT_LIST_HEAD(&cfqd->icq_list);
-
        cfqd->queue = q;
 
        init_timer(&cfqd->idle_slice_timer);

diff --git a/block/elevator.c b/block/elevator.c
index 31ffe76..c5c6214 100644 (file)
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -745,8 +745,6 @@ int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
 
        if (e->type->ops.elevator_set_req_fn)
                return e->type->ops.elevator_set_req_fn(q, rq, gfp_mask);
-
-       rq->elevator_private[0] = NULL;
        return 0;
 }
 

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 65c2f8c..8bca048 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -111,10 +111,14 @@ struct request {
         * Three pointers are available for the IO schedulers, if they need
         * more they have to dynamically allocate it.  Flush requests are
         * never put on the IO scheduler. So let the flush fields share
-        * space with the three elevator_private pointers.
+        * space with the elevator data.
         */
        union {
-               void *elevator_private[3];
+               struct {
+                       struct io_cq            *icq;
+                       void                    *priv[2];
+               } elv;
+
                struct {
                        unsigned int            seq;
                        struct list_head        list;
@@ -357,6 +361,8 @@ struct request_queue {
        struct timer_list       timeout;
        struct list_head        timeout_list;
 
+       struct list_head        icq_list;
+
        struct queue_limits     limits;
 
        /*