block: share request flush fields with elevator_private
Flush requests are never put on the IO scheduler. Convert request
structure's elevator_private* into an array and have the flush fields
share a union with it.
Reclaim the space lost in 'struct request' by moving 'completion_data'
back in the union with 'rb_node'.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 4cd59b0..968455c 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -54,9 +54,9 @@
#define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
#define RQ_CIC(rq) \
- ((struct cfq_io_context *) (rq)->elevator_private)
-#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
-#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private3)
+ ((struct cfq_io_context *) (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])
static struct kmem_cache *cfq_pool;
static struct kmem_cache *cfq_ioc_pool;
@@ -3589,12 +3589,12 @@
put_io_context(RQ_CIC(rq)->ioc);
- rq->elevator_private = NULL;
- rq->elevator_private2 = NULL;
+ rq->elevator_private[0] = NULL;
+ rq->elevator_private[1] = NULL;
/* Put down rq reference on cfqg */
cfq_put_cfqg(RQ_CFQG(rq));
- rq->elevator_private3 = NULL;
+ rq->elevator_private[2] = NULL;
cfq_put_queue(cfqq);
}
@@ -3685,9 +3685,9 @@
spin_unlock_irqrestore(q->queue_lock, flags);
- rq->elevator_private = cic;
- rq->elevator_private2 = cfqq;
- rq->elevator_private3 = cfq_ref_get_cfqg(cfqq->cfqg);
+ rq->elevator_private[0] = cic;
+ rq->elevator_private[1] = cfqq;
+ rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg);
return 0;
queue_fail:
diff --git a/block/elevator.c b/block/elevator.c
index 270e097..f98e92e 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -764,7 +764,7 @@
if (e->ops->elevator_set_req_fn)
return e->ops->elevator_set_req_fn(q, rq, gfp_mask);
- rq->elevator_private = NULL;
+ rq->elevator_private[0] = NULL;
return 0;
}
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 6d7e9af..12bb426 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -99,25 +99,26 @@
/*
* The rb_node is only used inside the io scheduler, requests
* are pruned when moved to the dispatch queue. So let the
- * flush fields share space with the rb_node.
+ * completion_data share space with the rb_node.
*/
union {
struct rb_node rb_node; /* sort/lookup */
- struct {
- unsigned int seq;
- struct list_head list;
- } flush;
+ void *completion_data;
};
- void *completion_data;
-
/*
* Three pointers are available for the IO schedulers, if they need
- * more they have to dynamically allocate it.
+ * 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.
*/
- void *elevator_private;
- void *elevator_private2;
- void *elevator_private3;
+ union {
+ void *elevator_private[3];
+ struct {
+ unsigned int seq;
+ struct list_head list;
+ } flush;
+ };
struct gendisk *rq_disk;
unsigned long start_time;