Merge branch 'merge'

5 files changed, 94 insertions, 56 deletions

diff --git a/block/as-iosched.c b/block/as-iosched.c
index e25a5d79ab27..a7caf35ca0c2 100644
--- a/block/as-iosched.c
+++ b/block/as-iosched.c
@@ -1648,17 +1648,17 @@ static void as_exit_queue(elevator_t *e)
  * initialize elevator private data (as_data), and alloc a arq for
  * each request on the free lists
  */
-static int as_init_queue(request_queue_t *q, elevator_t *e)
+static void *as_init_queue(request_queue_t *q, elevator_t *e)
 {
 	struct as_data *ad;
 	int i;
 
 	if (!arq_pool)
-		return -ENOMEM;
+		return NULL;
 
 	ad = kmalloc_node(sizeof(*ad), GFP_KERNEL, q->node);
 	if (!ad)
-		return -ENOMEM;
+		return NULL;
 	memset(ad, 0, sizeof(*ad));
 
 	ad->q = q; /* Identify what queue the data belongs to */
@@ -1667,7 +1667,7 @@ static int as_init_queue(request_queue_t *q, elevator_t *e)
 				GFP_KERNEL, q->node);
 	if (!ad->hash) {
 		kfree(ad);
-		return -ENOMEM;
+		return NULL;
 	}
 
 	ad->arq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
@@ -1675,7 +1675,7 @@ static int as_init_queue(request_queue_t *q, elevator_t *e)
 	if (!ad->arq_pool) {
 		kfree(ad->hash);
 		kfree(ad);
-		return -ENOMEM;
+		return NULL;
 	}
 
 	/* anticipatory scheduling helpers */
@@ -1696,14 +1696,13 @@ static int as_init_queue(request_queue_t *q, elevator_t *e)
 	ad->antic_expire = default_antic_expire;
 	ad->batch_expire[REQ_SYNC] = default_read_batch_expire;
 	ad->batch_expire[REQ_ASYNC] = default_write_batch_expire;
-	e->elevator_data = ad;
 
 	ad->current_batch_expires = jiffies + ad->batch_expire[REQ_SYNC];
 	ad->write_batch_count = ad->batch_expire[REQ_ASYNC] / 10;
 	if (ad->write_batch_count < 2)
 		ad->write_batch_count = 2;
 
-	return 0;
+	return ad;
 }
 
 /*
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 11ce6aaf1bd0..a46d030e092a 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -133,6 +133,7 @@ struct cfq_data {
 	mempool_t *crq_pool;
 
 	int rq_in_driver;
+	int hw_tag;
 
 	/*
 	 * schedule slice state info
@@ -500,10 +501,13 @@ static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted)
 
 	/*
 	 * if queue was preempted, just add to front to be fair. busy_rr
-	 * isn't sorted.
+	 * isn't sorted, but insert at the back for fairness.
 	 */
 	if (preempted || list == &cfqd->busy_rr) {
-		list_add(&cfqq->cfq_list, list);
+		if (preempted)
+			list = list->prev;
+
+		list_add_tail(&cfqq->cfq_list, list);
 		return;
 	}
 
@@ -664,6 +668,15 @@ static void cfq_activate_request(request_queue_t *q, struct request *rq)
 	struct cfq_data *cfqd = q->elevator->elevator_data;
 
 	cfqd->rq_in_driver++;
+
+	/*
+	 * If the depth is larger 1, it really could be queueing. But lets
+	 * make the mark a little higher - idling could still be good for
+	 * low queueing, and a low queueing number could also just indicate
+	 * a SCSI mid layer like behaviour where limit+1 is often seen.
+	 */
+	if (!cfqd->hw_tag && cfqd->rq_in_driver > 4)
+		cfqd->hw_tag = 1;
 }
 
 static void cfq_deactivate_request(request_queue_t *q, struct request *rq)
@@ -879,6 +892,13 @@ static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd)
 		cfqq = list_entry_cfqq(cfqd->cur_rr.next);
 
 	/*
+	 * If no new queues are available, check if the busy list has some
+	 * before falling back to idle io.
+	 */
+	if (!cfqq && !list_empty(&cfqd->busy_rr))
+		cfqq = list_entry_cfqq(cfqd->busy_rr.next);
+
+	/*
 	 * if we have idle queues and no rt or be queues had pending
 	 * requests, either allow immediate service if the grace period
 	 * has passed or arm the idle grace timer
@@ -1458,7 +1478,8 @@ retry:
 		 * set ->slice_left to allow preemption for a new process
 		 */
 		cfqq->slice_left = 2 * cfqd->cfq_slice_idle;
-		cfq_mark_cfqq_idle_window(cfqq);
+		if (!cfqd->hw_tag)
+			cfq_mark_cfqq_idle_window(cfqq);
 		cfq_mark_cfqq_prio_changed(cfqq);
 		cfq_init_prio_data(cfqq);
 	}
@@ -1649,7 +1670,7 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 {
 	int enable_idle = cfq_cfqq_idle_window(cfqq);
 
-	if (!cic->ioc->task || !cfqd->cfq_slice_idle)
+	if (!cic->ioc->task || !cfqd->cfq_slice_idle || cfqd->hw_tag)
 		enable_idle = 0;
 	else if (sample_valid(cic->ttime_samples)) {
 		if (cic->ttime_mean > cfqd->cfq_slice_idle)
@@ -1740,14 +1761,24 @@ cfq_crq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 
 	cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq);
 
+	cic = crq->io_context;
+
 	/*
 	 * we never wait for an async request and we don't allow preemption
 	 * of an async request. so just return early
 	 */
-	if (!cfq_crq_is_sync(crq))
+	if (!cfq_crq_is_sync(crq)) {
+		/*
+		 * sync process issued an async request, if it's waiting
+		 * then expire it and kick rq handling.
+		 */
+		if (cic == cfqd->active_cic &&
+		    del_timer(&cfqd->idle_slice_timer)) {
+			cfq_slice_expired(cfqd, 0);
+			cfq_start_queueing(cfqd, cfqq);
+		}
 		return;
-
-	cic = crq->io_context;
+	}
 
 	cfq_update_io_thinktime(cfqd, cic);
 	cfq_update_io_seektime(cfqd, cic, crq);
@@ -2165,10 +2196,9 @@ static void cfq_idle_class_timer(unsigned long data)
 	 * race with a non-idle queue, reset timer
 	 */
 	end = cfqd->last_end_request + CFQ_IDLE_GRACE;
-	if (!time_after_eq(jiffies, end)) {
-		cfqd->idle_class_timer.expires = end;
-		add_timer(&cfqd->idle_class_timer);
-	} else
+	if (!time_after_eq(jiffies, end))
+		mod_timer(&cfqd->idle_class_timer, end);
+	else
 		cfq_schedule_dispatch(cfqd);
 
 	spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
@@ -2221,14 +2251,14 @@ static void cfq_exit_queue(elevator_t *e)
 	kfree(cfqd);
 }
 
-static int cfq_init_queue(request_queue_t *q, elevator_t *e)
+static void *cfq_init_queue(request_queue_t *q, elevator_t *e)
 {
 	struct cfq_data *cfqd;
 	int i;
 
 	cfqd = kmalloc(sizeof(*cfqd), GFP_KERNEL);
 	if (!cfqd)
-		return -ENOMEM;
+		return NULL;
 
 	memset(cfqd, 0, sizeof(*cfqd));
 
@@ -2258,8 +2288,6 @@ static int cfq_init_queue(request_queue_t *q, elevator_t *e)
 	for (i = 0; i < CFQ_QHASH_ENTRIES; i++)
 		INIT_HLIST_HEAD(&cfqd->cfq_hash[i]);
 
-	e->elevator_data = cfqd;
-
 	cfqd->queue = q;
 
 	cfqd->max_queued = q->nr_requests / 4;
@@ -2286,14 +2314,14 @@ static int cfq_init_queue(request_queue_t *q, elevator_t *e)
 	cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
 	cfqd->cfq_slice_idle = cfq_slice_idle;
 
-	return 0;
+	return cfqd;
 out_crqpool:
 	kfree(cfqd->cfq_hash);
 out_cfqhash:
 	kfree(cfqd->crq_hash);
 out_crqhash:
 	kfree(cfqd);
-	return -ENOMEM;
+	return NULL;
 }
 
 static void cfq_slab_kill(void)
diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
index 399fa1e60e1f..3bd0415a9828 100644
--- a/block/deadline-iosched.c
+++ b/block/deadline-iosched.c
@@ -613,24 +613,24 @@ static void deadline_exit_queue(elevator_t *e)
  * initialize elevator private data (deadline_data), and alloc a drq for
  * each request on the free lists
  */
-static int deadline_init_queue(request_queue_t *q, elevator_t *e)
+static void *deadline_init_queue(request_queue_t *q, elevator_t *e)
 {
 	struct deadline_data *dd;
 	int i;
 
 	if (!drq_pool)
-		return -ENOMEM;
+		return NULL;
 
 	dd = kmalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
 	if (!dd)
-		return -ENOMEM;
+		return NULL;
 	memset(dd, 0, sizeof(*dd));
 
 	dd->hash = kmalloc_node(sizeof(struct list_head)*DL_HASH_ENTRIES,
 				GFP_KERNEL, q->node);
 	if (!dd->hash) {
 		kfree(dd);
-		return -ENOMEM;
+		return NULL;
 	}
 
 	dd->drq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
@@ -638,7 +638,7 @@ static int deadline_init_queue(request_queue_t *q, elevator_t *e)
 	if (!dd->drq_pool) {
 		kfree(dd->hash);
 		kfree(dd);
-		return -ENOMEM;
+		return NULL;
 	}
 
 	for (i = 0; i < DL_HASH_ENTRIES; i++)
@@ -653,8 +653,7 @@ static int deadline_init_queue(request_queue_t *q, elevator_t *e)
 	dd->writes_starved = writes_starved;
 	dd->front_merges = 1;
 	dd->fifo_batch = fifo_batch;
-	e->elevator_data = dd;
-	return 0;
+	return dd;
 }
 
 static void deadline_put_request(request_queue_t *q, struct request *rq)
diff --git a/block/elevator.c b/block/elevator.c
index 8768a367fdde..a0afdd317cef 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -121,16 +121,16 @@ static struct elevator_type *elevator_get(const char *name)
 	return e;
 }
 
-static int elevator_attach(request_queue_t *q, struct elevator_queue *eq)
+static void *elevator_init_queue(request_queue_t *q, struct elevator_queue *eq)
 {
-	int ret = 0;
+	return eq->ops->elevator_init_fn(q, eq);
+}
 
+static void elevator_attach(request_queue_t *q, struct elevator_queue *eq,
+			   void *data)
+{
 	q->elevator = eq;
-
-	if (eq->ops->elevator_init_fn)
-		ret = eq->ops->elevator_init_fn(q, eq);
-
-	return ret;
+	eq->elevator_data = data;
 }
 
 static char chosen_elevator[16];
@@ -181,6 +181,7 @@ int elevator_init(request_queue_t *q, char *name)
 	struct elevator_type *e = NULL;
 	struct elevator_queue *eq;
 	int ret = 0;
+	void *data;
 
 	INIT_LIST_HEAD(&q->queue_head);
 	q->last_merge = NULL;
@@ -202,10 +203,13 @@ int elevator_init(request_queue_t *q, char *name)
 	if (!eq)
 		return -ENOMEM;
 
-	ret = elevator_attach(q, eq);
-	if (ret)
+	data = elevator_init_queue(q, eq);
+	if (!data) {
 		kobject_put(&eq->kobj);
+		return -ENOMEM;
+	}
 
+	elevator_attach(q, eq, data);
 	return ret;
 }
 
@@ -722,13 +726,16 @@ int elv_register_queue(struct request_queue *q)
 	return error;
 }
 
+static void __elv_unregister_queue(elevator_t *e)
+{
+	kobject_uevent(&e->kobj, KOBJ_REMOVE);
+	kobject_del(&e->kobj);
+}
+
 void elv_unregister_queue(struct request_queue *q)
 {
-	if (q) {
-		elevator_t *e = q->elevator;
-		kobject_uevent(&e->kobj, KOBJ_REMOVE);
-		kobject_del(&e->kobj);
-	}
+	if (q)
+		__elv_unregister_queue(q->elevator);
 }
 
 int elv_register(struct elevator_type *e)
@@ -780,6 +787,7 @@ EXPORT_SYMBOL_GPL(elv_unregister);
 static int elevator_switch(request_queue_t *q, struct elevator_type *new_e)
 {
 	elevator_t *old_elevator, *e;
+	void *data;
 
 	/*
 	 * Allocate new elevator
@@ -788,6 +796,12 @@ static int elevator_switch(request_queue_t *q, struct elevator_type *new_e)
 	if (!e)
 		return 0;
 
+	data = elevator_init_queue(q, e);
+	if (!data) {
+		kobject_put(&e->kobj);
+		return 0;
+	}
+
 	/*
 	 * Turn on BYPASS and drain all requests w/ elevator private data
 	 */
@@ -806,19 +820,19 @@ static int elevator_switch(request_queue_t *q, struct elevator_type *new_e)
 		elv_drain_elevator(q);
 	}
 
-	spin_unlock_irq(q->queue_lock);
-
 	/*
-	 * unregister old elevator data
+	 * Remember old elevator.
 	 */
-	elv_unregister_queue(q);
 	old_elevator = q->elevator;
 
 	/*
 	 * attach and start new elevator
 	 */
-	if (elevator_attach(q, e))
-		goto fail;
+	elevator_attach(q, e, data);
+
+	spin_unlock_irq(q->queue_lock);
+
+	__elv_unregister_queue(old_elevator);
 
 	if (elv_register_queue(q))
 		goto fail_register;
@@ -837,7 +851,6 @@ fail_register:
 	 */
 	elevator_exit(e);
 	e = NULL;
-fail:
 	q->elevator = old_elevator;
 	elv_register_queue(q);
 	clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
diff --git a/block/noop-iosched.c b/block/noop-iosched.c
index f370e4a7fe6d..56a7c620574f 100644
--- a/block/noop-iosched.c
+++ b/block/noop-iosched.c
@@ -65,16 +65,15 @@ noop_latter_request(request_queue_t *q, struct request *rq)
 	return list_entry(rq->queuelist.next, struct request, queuelist);
 }
 
-static int noop_init_queue(request_queue_t *q, elevator_t *e)
+static void *noop_init_queue(request_queue_t *q, elevator_t *e)
 {
 	struct noop_data *nd;
 
 	nd = kmalloc(sizeof(*nd), GFP_KERNEL);
 	if (!nd)
-		return -ENOMEM;
+		return NULL;
 	INIT_LIST_HEAD(&nd->queue);
-	e->elevator_data = nd;
-	return 0;
+	return nd;
 }
 
 static void noop_exit_queue(elevator_t *e)