1 files changed, 111 insertions, 161 deletions

diff --git a/block/elevator.c b/block/elevator.c
index 66343d6917d..f016855a46b 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -61,8 +61,8 @@ static int elv_iosched_allow_merge(struct request *rq, struct bio *bio)
 	struct request_queue *q = rq->q;
 	struct elevator_queue *e = q->elevator;
 
-	if (e->ops->elevator_allow_merge_fn)
-		return e->ops->elevator_allow_merge_fn(q, rq, bio);
+	if (e->type->ops.elevator_allow_merge_fn)
+		return e->type->ops.elevator_allow_merge_fn(q, rq, bio);
 
 	return 1;
 }
@@ -70,39 +70,9 @@ static int elv_iosched_allow_merge(struct request *rq, struct bio *bio)
 /*
  * can we safely merge with this request?
  */
-int elv_rq_merge_ok(struct request *rq, struct bio *bio)
+bool elv_rq_merge_ok(struct request *rq, struct bio *bio)
 {
-	if (!rq_mergeable(rq))
-		return 0;
-
-	/*
-	 * Don't merge file system requests and discard requests
-	 */
-	if ((bio->bi_rw & REQ_DISCARD) != (rq->bio->bi_rw & REQ_DISCARD))
-		return 0;
-
-	/*
-	 * Don't merge discard requests and secure discard requests
-	 */
-	if ((bio->bi_rw & REQ_SECURE) != (rq->bio->bi_rw & REQ_SECURE))
-		return 0;
-
-	/*
-	 * different data direction or already started, don't merge
-	 */
-	if (bio_data_dir(bio) != rq_data_dir(rq))
-		return 0;
-
-	/*
-	 * must be same device and not a special request
-	 */
-	if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special)
-		return 0;
-
-	/*
-	 * only merge integrity protected bio into ditto rq
-	 */
-	if (bio_integrity(bio) != blk_integrity_rq(rq))
+	if (!blk_rq_merge_ok(rq, bio))
 		return 0;
 
 	if (!elv_iosched_allow_merge(rq, bio))
@@ -112,23 +82,6 @@ int elv_rq_merge_ok(struct request *rq, struct bio *bio)
 }
 EXPORT_SYMBOL(elv_rq_merge_ok);
 
-int elv_try_merge(struct request *__rq, struct bio *bio)
-{
-	int ret = ELEVATOR_NO_MERGE;
-
-	/*
-	 * we can merge and sequence is ok, check if it's possible
-	 */
-	if (elv_rq_merge_ok(__rq, bio)) {
-		if (blk_rq_pos(__rq) + blk_rq_sectors(__rq) == bio->bi_sector)
-			ret = ELEVATOR_BACK_MERGE;
-		else if (blk_rq_pos(__rq) - bio_sectors(bio) == bio->bi_sector)
-			ret = ELEVATOR_FRONT_MERGE;
-	}
-
-	return ret;
-}
-
 static struct elevator_type *elevator_find(const char *name)
 {
 	struct elevator_type *e;
@@ -168,17 +121,13 @@ static struct elevator_type *elevator_get(const char *name)
 	return e;
 }
 
-static void *elevator_init_queue(struct request_queue *q,
-				 struct elevator_queue *eq)
-{
-	return eq->ops->elevator_init_fn(q);
-}
-
-static void elevator_attach(struct request_queue *q, struct elevator_queue *eq,
-			   void *data)
+static int elevator_init_queue(struct request_queue *q,
+			       struct elevator_queue *eq)
 {
-	q->elevator = eq;
-	eq->elevator_data = data;
+	eq->elevator_data = eq->type->ops.elevator_init_fn(q);
+	if (eq->elevator_data)
+		return 0;
+	return -ENOMEM;
 }
 
 static char chosen_elevator[ELV_NAME_MAX];
@@ -207,8 +156,7 @@ static struct elevator_queue *elevator_alloc(struct request_queue *q,
 	if (unlikely(!eq))
 		goto err;
 
-	eq->ops = &e->ops;
-	eq->elevator_type = e;
+	eq->type = e;
 	kobject_init(&eq->kobj, &elv_ktype);
 	mutex_init(&eq->sysfs_lock);
 
@@ -232,7 +180,7 @@ static void elevator_release(struct kobject *kobj)
 	struct elevator_queue *e;
 
 	e = container_of(kobj, struct elevator_queue, kobj);
-	elevator_put(e->elevator_type);
+	elevator_put(e->type);
 	kfree(e->hash);
 	kfree(e);
 }
@@ -241,7 +189,7 @@ int elevator_init(struct request_queue *q, char *name)
 {
 	struct elevator_type *e = NULL;
 	struct elevator_queue *eq;
-	void *data;
+	int err;
 
 	if (unlikely(q->elevator))
 		return 0;
@@ -278,13 +226,13 @@ int elevator_init(struct request_queue *q, char *name)
 	if (!eq)
 		return -ENOMEM;
 
-	data = elevator_init_queue(q, eq);
-	if (!data) {
+	err = elevator_init_queue(q, eq);
+	if (err) {
 		kobject_put(&eq->kobj);
-		return -ENOMEM;
+		return err;
 	}
 
-	elevator_attach(q, eq, data);
+	q->elevator = eq;
 	return 0;
 }
 EXPORT_SYMBOL(elevator_init);
@@ -292,9 +240,8 @@ EXPORT_SYMBOL(elevator_init);
 void elevator_exit(struct elevator_queue *e)
 {
 	mutex_lock(&e->sysfs_lock);
-	if (e->ops->elevator_exit_fn)
-		e->ops->elevator_exit_fn(e);
-	e->ops = NULL;
+	if (e->type->ops.elevator_exit_fn)
+		e->type->ops.elevator_exit_fn(e);
 	mutex_unlock(&e->sysfs_lock);
 
 	kobject_put(&e->kobj);
@@ -484,8 +431,8 @@ int elv_merge(struct request_queue *q, struct request **req, struct bio *bio)
 	/*
 	 * First try one-hit cache.
 	 */
-	if (q->last_merge) {
-		ret = elv_try_merge(q->last_merge, bio);
+	if (q->last_merge && elv_rq_merge_ok(q->last_merge, bio)) {
+		ret = blk_try_merge(q->last_merge, bio);
 		if (ret != ELEVATOR_NO_MERGE) {
 			*req = q->last_merge;
 			return ret;
@@ -504,8 +451,8 @@ int elv_merge(struct request_queue *q, struct request **req, struct bio *bio)
 		return ELEVATOR_BACK_MERGE;
 	}
 
-	if (e->ops->elevator_merge_fn)
-		return e->ops->elevator_merge_fn(q, req, bio);
+	if (e->type->ops.elevator_merge_fn)
+		return e->type->ops.elevator_merge_fn(q, req, bio);
 
 	return ELEVATOR_NO_MERGE;
 }
@@ -548,8 +495,8 @@ void elv_merged_request(struct request_queue *q, struct request *rq, int type)
 {
 	struct elevator_queue *e = q->elevator;
 
-	if (e->ops->elevator_merged_fn)
-		e->ops->elevator_merged_fn(q, rq, type);
+	if (e->type->ops.elevator_merged_fn)
+		e->type->ops.elevator_merged_fn(q, rq, type);
 
 	if (type == ELEVATOR_BACK_MERGE)
 		elv_rqhash_reposition(q, rq);
@@ -563,8 +510,8 @@ void elv_merge_requests(struct request_queue *q, struct request *rq,
 	struct elevator_queue *e = q->elevator;
 	const int next_sorted = next->cmd_flags & REQ_SORTED;
 
-	if (next_sorted && e->ops->elevator_merge_req_fn)
-		e->ops->elevator_merge_req_fn(q, rq, next);
+	if (next_sorted && e->type->ops.elevator_merge_req_fn)
+		e->type->ops.elevator_merge_req_fn(q, rq, next);
 
 	elv_rqhash_reposition(q, rq);
 
@@ -581,8 +528,8 @@ void elv_bio_merged(struct request_queue *q, struct request *rq,
 {
 	struct elevator_queue *e = q->elevator;
 
-	if (e->ops->elevator_bio_merged_fn)
-		e->ops->elevator_bio_merged_fn(q, rq, bio);
+	if (e->type->ops.elevator_bio_merged_fn)
+		e->type->ops.elevator_bio_merged_fn(q, rq, bio);
 }
 
 void elv_requeue_request(struct request_queue *q, struct request *rq)
@@ -608,12 +555,12 @@ void elv_drain_elevator(struct request_queue *q)
 
 	lockdep_assert_held(q->queue_lock);
 
-	while (q->elevator->ops->elevator_dispatch_fn(q, 1))
+	while (q->elevator->type->ops.elevator_dispatch_fn(q, 1))
 		;
 	if (q->nr_sorted && printed++ < 10) {
 		printk(KERN_ERR "%s: forced dispatching is broken "
 		       "(nr_sorted=%u), please report this\n",
-		       q->elevator->elevator_type->elevator_name, q->nr_sorted);
+		       q->elevator->type->elevator_name, q->nr_sorted);
 	}
 }
 
@@ -702,7 +649,7 @@ void __elv_add_request(struct request_queue *q, struct request *rq, int where)
 		 * rq cannot be accessed after calling
 		 * elevator_add_req_fn.
 		 */
-		q->elevator->ops->elevator_add_req_fn(q, rq);
+		q->elevator->type->ops.elevator_add_req_fn(q, rq);
 		break;
 
 	case ELEVATOR_INSERT_FLUSH:
@@ -731,8 +678,8 @@ struct request *elv_latter_request(struct request_queue *q, struct request *rq)
 {
 	struct elevator_queue *e = q->elevator;
 
-	if (e->ops->elevator_latter_req_fn)
-		return e->ops->elevator_latter_req_fn(q, rq);
+	if (e->type->ops.elevator_latter_req_fn)
+		return e->type->ops.elevator_latter_req_fn(q, rq);
 	return NULL;
 }
 
@@ -740,8 +687,8 @@ struct request *elv_former_request(struct request_queue *q, struct request *rq)
 {
 	struct elevator_queue *e = q->elevator;
 
-	if (e->ops->elevator_former_req_fn)
-		return e->ops->elevator_former_req_fn(q, rq);
+	if (e->type->ops.elevator_former_req_fn)
+		return e->type->ops.elevator_former_req_fn(q, rq);
 	return NULL;
 }
 
@@ -749,10 +696,8 @@ int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
 {
 	struct elevator_queue *e = q->elevator;
 
-	if (e->ops->elevator_set_req_fn)
-		return e->ops->elevator_set_req_fn(q, rq, gfp_mask);
-
-	rq->elevator_private[0] = NULL;
+	if (e->type->ops.elevator_set_req_fn)
+		return e->type->ops.elevator_set_req_fn(q, rq, gfp_mask);
 	return 0;
 }
 
@@ -760,16 +705,16 @@ void elv_put_request(struct request_queue *q, struct request *rq)
 {
 	struct elevator_queue *e = q->elevator;
 
-	if (e->ops->elevator_put_req_fn)
-		e->ops->elevator_put_req_fn(rq);
+	if (e->type->ops.elevator_put_req_fn)
+		e->type->ops.elevator_put_req_fn(rq);
 }
 
 int elv_may_queue(struct request_queue *q, int rw)
 {
 	struct elevator_queue *e = q->elevator;
 
-	if (e->ops->elevator_may_queue_fn)
-		return e->ops->elevator_may_queue_fn(q, rw);
+	if (e->type->ops.elevator_may_queue_fn)
+		return e->type->ops.elevator_may_queue_fn(q, rw);
 
 	return ELV_MQUEUE_MAY;
 }
@@ -804,8 +749,8 @@ void elv_completed_request(struct request_queue *q, struct request *rq)
 	if (blk_account_rq(rq)) {
 		q->in_flight[rq_is_sync(rq)]--;
 		if ((rq->cmd_flags & REQ_SORTED) &&
-		    e->ops->elevator_completed_req_fn)
-			e->ops->elevator_completed_req_fn(q, rq);
+		    e->type->ops.elevator_completed_req_fn)
+			e->type->ops.elevator_completed_req_fn(q, rq);
 	}
 }
 
@@ -823,7 +768,7 @@ elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 
 	e = container_of(kobj, struct elevator_queue, kobj);
 	mutex_lock(&e->sysfs_lock);
-	error = e->ops ? entry->show(e, page) : -ENOENT;
+	error = e->type ? entry->show(e, page) : -ENOENT;
 	mutex_unlock(&e->sysfs_lock);
 	return error;
 }
@@ -841,7 +786,7 @@ elv_attr_store(struct kobject *kobj, struct attribute *attr,
 
 	e = container_of(kobj, struct elevator_queue, kobj);
 	mutex_lock(&e->sysfs_lock);
-	error = e->ops ? entry->store(e, page, length) : -ENOENT;
+	error = e->type ? entry->store(e, page, length) : -ENOENT;
 	mutex_unlock(&e->sysfs_lock);
 	return error;
 }
@@ -856,14 +801,13 @@ static struct kobj_type elv_ktype = {
 	.release	= elevator_release,
 };
 
-int elv_register_queue(struct request_queue *q)
+int __elv_register_queue(struct request_queue *q, struct elevator_queue *e)
 {
-	struct elevator_queue *e = q->elevator;
 	int error;
 
 	error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched");
 	if (!error) {
-		struct elv_fs_entry *attr = e->elevator_type->elevator_attrs;
+		struct elv_fs_entry *attr = e->type->elevator_attrs;
 		if (attr) {
 			while (attr->attr.name) {
 				if (sysfs_create_file(&e->kobj, &attr->attr))
@@ -876,31 +820,55 @@ int elv_register_queue(struct request_queue *q)
 	}
 	return error;
 }
-EXPORT_SYMBOL(elv_register_queue);
 
-static void __elv_unregister_queue(struct elevator_queue *e)
+int elv_register_queue(struct request_queue *q)
 {
-	kobject_uevent(&e->kobj, KOBJ_REMOVE);
-	kobject_del(&e->kobj);
-	e->registered = 0;
+	return __elv_register_queue(q, q->elevator);
 }
+EXPORT_SYMBOL(elv_register_queue);
 
 void elv_unregister_queue(struct request_queue *q)
 {
-	if (q)
-		__elv_unregister_queue(q->elevator);
+	if (q) {
+		struct elevator_queue *e = q->elevator;
+
+		kobject_uevent(&e->kobj, KOBJ_REMOVE);
+		kobject_del(&e->kobj);
+		e->registered = 0;
+	}
 }
 EXPORT_SYMBOL(elv_unregister_queue);
 
-void elv_register(struct elevator_type *e)
+int elv_register(struct elevator_type *e)
 {
 	char *def = "";
 
+	/* create icq_cache if requested */
+	if (e->icq_size) {
+		if (WARN_ON(e->icq_size < sizeof(struct io_cq)) ||
+		    WARN_ON(e->icq_align < __alignof__(struct io_cq)))
+			return -EINVAL;
+
+		snprintf(e->icq_cache_name, sizeof(e->icq_cache_name),
+			 "%s_io_cq", e->elevator_name);
+		e->icq_cache = kmem_cache_create(e->icq_cache_name, e->icq_size,
+						 e->icq_align, 0, NULL);
+		if (!e->icq_cache)
+			return -ENOMEM;
+	}
+
+	/* register, don't allow duplicate names */
 	spin_lock(&elv_list_lock);
-	BUG_ON(elevator_find(e->elevator_name));
+	if (elevator_find(e->elevator_name)) {
+		spin_unlock(&elv_list_lock);
+		if (e->icq_cache)
+			kmem_cache_destroy(e->icq_cache);
+		return -EBUSY;
+	}
 	list_add_tail(&e->list, &elv_list);
 	spin_unlock(&elv_list_lock);
 
+	/* print pretty message */
 	if (!strcmp(e->elevator_name, chosen_elevator) ||
 			(!*chosen_elevator &&
 			 !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED)))
@@ -908,30 +876,26 @@ void elv_register(struct elevator_type *e)
 
 	printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name,
 								def);
+	return 0;
 }
 EXPORT_SYMBOL_GPL(elv_register);
 
 void elv_unregister(struct elevator_type *e)
 {
-	struct task_struct *g, *p;
+	/* unregister */
+	spin_lock(&elv_list_lock);
+	list_del_init(&e->list);
+	spin_unlock(&elv_list_lock);
 
 	/*
-	 * Iterate every thread in the process to remove the io contexts.
+	 * Destroy icq_cache if it exists.  icq's are RCU managed.  Make
+	 * sure all RCU operations are complete before proceeding.
 	 */
-	if (e->ops.trim) {
-		read_lock(&tasklist_lock);
-		do_each_thread(g, p) {
-			task_lock(p);
-			if (p->io_context)
-				e->ops.trim(p->io_context);
-			task_unlock(p);
-		} while_each_thread(g, p);
-		read_unlock(&tasklist_lock);
+	if (e->icq_cache) {
+		rcu_barrier();
+		kmem_cache_destroy(e->icq_cache);
+		e->icq_cache = NULL;
 	}
-
-	spin_lock(&elv_list_lock);
-	list_del_init(&e->list);
-	spin_unlock(&elv_list_lock);
 }
 EXPORT_SYMBOL_GPL(elv_unregister);
 
@@ -944,54 +908,41 @@ EXPORT_SYMBOL_GPL(elv_unregister);
 static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
 {
 	struct elevator_queue *old_elevator, *e;
-	void *data;
 	int err;
 
-	/*
-	 * Allocate new elevator
-	 */
+	/* allocate new elevator */
 	e = elevator_alloc(q, new_e);
 	if (!e)
 		return -ENOMEM;
 
-	data = elevator_init_queue(q, e);
-	if (!data) {
+	err = elevator_init_queue(q, e);
+	if (err) {
 		kobject_put(&e->kobj);
-		return -ENOMEM;
+		return err;
 	}
 
-	/*
-	 * Turn on BYPASS and drain all requests w/ elevator private data
-	 */
+	/* turn on BYPASS and drain all requests w/ elevator private data */
 	elv_quiesce_start(q);
 
-	/*
-	 * Remember old elevator.
-	 */
-	old_elevator = q->elevator;
-
-	/*
-	 * attach and start new elevator
-	 */
-	spin_lock_irq(q->queue_lock);
-	elevator_attach(q, e, data);
-	spin_unlock_irq(q->queue_lock);
-
-	if (old_elevator->registered) {
-		__elv_unregister_queue(old_elevator);
-
-		err = elv_register_queue(q);
+	/* unregister old queue, register new one and kill old elevator */
+	if (q->elevator->registered) {
+		elv_unregister_queue(q);
+		err = __elv_register_queue(q, e);
 		if (err)
 			goto fail_register;
 	}
 
-	/*
-	 * finally exit old elevator and turn off BYPASS.
-	 */
+	/* done, clear io_cq's, switch elevators and turn off BYPASS */
+	spin_lock_irq(q->queue_lock);
+	ioc_clear_queue(q);
+	old_elevator = q->elevator;
+	q->elevator = e;
+	spin_unlock_irq(q->queue_lock);
+
 	elevator_exit(old_elevator);
 	elv_quiesce_end(q);
 
-	blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name);
+	blk_add_trace_msg(q, "elv switch: %s", e->type->elevator_name);
 
 	return 0;
 
@@ -1001,7 +952,6 @@ fail_register:
 	 * one again (along with re-adding the sysfs dir)
 	 */
 	elevator_exit(e);
-	q->elevator = old_elevator;
 	elv_register_queue(q);
 	elv_quiesce_end(q);
 
@@ -1026,7 +976,7 @@ int elevator_change(struct request_queue *q, const char *name)
 		return -EINVAL;
 	}
 
-	if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) {
+	if (!strcmp(elevator_name, q->elevator->type->elevator_name)) {
 		elevator_put(e);
 		return 0;
 	}
@@ -1061,7 +1011,7 @@ ssize_t elv_iosched_show(struct request_queue *q, char *name)
 	if (!q->elevator || !blk_queue_stackable(q))
 		return sprintf(name, "none\n");
 
-	elv = e->elevator_type;
+	elv = e->type;
 
 	spin_lock(&elv_list_lock);
 	list_for_each_entry(__e, &elv_list, list) {