Merge branch 'for-3.3/core' of git://git.kernel.dk/linux-block

* 'for-3.3/core' of git://git.kernel.dk/linux-block: (37 commits)
  Revert "block: recursive merge requests"
  block: Stop using macro stubs for the bio data integrity calls
  blockdev: convert some macros to static inlines
  fs: remove unneeded plug in mpage_readpages()
  block: Add BLKROTATIONAL ioctl
  block: Introduce blk_set_stacking_limits function
  block: remove WARN_ON_ONCE() in exit_io_context()
  block: an exiting task should be allowed to create io_context
  block: ioc_cgroup_changed() needs to be exported
  block: recursive merge requests
  block, cfq: fix empty queue crash caused by request merge
  block, cfq: move icq creation and rq->elv.icq association to block core
  block, cfq: restructure io_cq creation path for io_context interface cleanup
  block, cfq: move io_cq exit/release to blk-ioc.c
  block, cfq: move icq cache management to block core
  block, cfq: move io_cq lookup to blk-ioc.c
  block, cfq: move cfqd->icq_list to request_queue and add request->elv.icq
  block, cfq: reorganize cfq_io_context into generic and cfq specific parts
  block: remove elevator_queue->ops
  block: reorder elevator switch sequence
  ...

Fix up conflicts in:
 - block/blk-cgroup.c
	Switch from can_attach_task to can_attach
 - block/cfq-iosched.c
	conflict with now removed cic index changes (we now use q->id instead)

16 files changed, 847 insertions, 821 deletions

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index b8c143d..fa8f263 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -1655,11 +1655,12 @@ static void blkiocg_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
 	struct io_context *ioc;
 
 	cgroup_taskset_for_each(task, cgrp, tset) {
-		task_lock(task);
-		ioc = task->io_context;
-		if (ioc)
-			ioc->cgroup_changed = 1;
-		task_unlock(task);
+		/* we don't lose anything even if ioc allocation fails */
+		ioc = get_task_io_context(task, GFP_ATOMIC, NUMA_NO_NODE);
+		if (ioc) {
+			ioc_cgroup_changed(ioc);
+			put_io_context(ioc, NULL);
+		}
 	}
 }
 
diff --git a/block/blk-core.c b/block/blk-core.c
index 15de223..e6c05a9 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -39,6 +39,8 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
 
+DEFINE_IDA(blk_queue_ida);
+
 /*
  * For the allocated request tables
  */
@@ -358,7 +360,8 @@ EXPORT_SYMBOL(blk_put_queue);
 void blk_drain_queue(struct request_queue *q, bool drain_all)
 {
 	while (true) {
-		int nr_rqs;
+		bool drain = false;
+		int i;
 
 		spin_lock_irq(q->queue_lock);
 
@@ -375,14 +378,25 @@ void blk_drain_queue(struct request_queue *q, bool drain_all)
 		if (!list_empty(&q->queue_head))
 			__blk_run_queue(q);
 
-		if (drain_all)
-			nr_rqs = q->rq.count[0] + q->rq.count[1];
-		else
-			nr_rqs = q->rq.elvpriv;
+		drain |= q->rq.elvpriv;
+
+		/*
+		 * Unfortunately, requests are queued at and tracked from
+		 * multiple places and there's no single counter which can
+		 * be drained.  Check all the queues and counters.
+		 */
+		if (drain_all) {
+			drain |= !list_empty(&q->queue_head);
+			for (i = 0; i < 2; i++) {
+				drain |= q->rq.count[i];
+				drain |= q->in_flight[i];
+				drain |= !list_empty(&q->flush_queue[i]);
+			}
+		}
 
 		spin_unlock_irq(q->queue_lock);
 
-		if (!nr_rqs)
+		if (!drain)
 			break;
 		msleep(10);
 	}
@@ -469,6 +483,10 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
 	if (!q)
 		return NULL;
 
+	q->id = ida_simple_get(&blk_queue_ida, 0, 0, GFP_KERNEL);
+	if (q->id < 0)
+		goto fail_q;
+
 	q->backing_dev_info.ra_pages =
 			(VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
 	q->backing_dev_info.state = 0;
@@ -477,20 +495,17 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
 	q->node = node_id;
 
 	err = bdi_init(&q->backing_dev_info);
-	if (err) {
-		kmem_cache_free(blk_requestq_cachep, q);
-		return NULL;
-	}
+	if (err)
+		goto fail_id;
 
-	if (blk_throtl_init(q)) {
-		kmem_cache_free(blk_requestq_cachep, q);
-		return NULL;
-	}
+	if (blk_throtl_init(q))
+		goto fail_id;
 
 	setup_timer(&q->backing_dev_info.laptop_mode_wb_timer,
 		    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);
@@ -508,6 +523,12 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
 	q->queue_lock = &q->__queue_lock;
 
 	return q;
+
+fail_id:
+	ida_simple_remove(&blk_queue_ida, q->id);
+fail_q:
+	kmem_cache_free(blk_requestq_cachep, q);
+	return NULL;
 }
 EXPORT_SYMBOL(blk_alloc_queue_node);
 
@@ -605,26 +626,31 @@ blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
 }
 EXPORT_SYMBOL(blk_init_allocated_queue);
 
-int blk_get_queue(struct request_queue *q)
+bool blk_get_queue(struct request_queue *q)
 {
-	if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
-		kobject_get(&q->kobj);
-		return 0;
+	if (likely(!blk_queue_dead(q))) {
+		__blk_get_queue(q);
+		return true;
 	}
 
-	return 1;
+	return false;
 }
 EXPORT_SYMBOL(blk_get_queue);
 
 static inline void blk_free_request(struct request_queue *q, struct request *rq)
 {
-	if (rq->cmd_flags & REQ_ELVPRIV)
+	if (rq->cmd_flags & REQ_ELVPRIV) {
 		elv_put_request(q, rq);
+		if (rq->elv.icq)
+			put_io_context(rq->elv.icq->ioc, q);
+	}
+
 	mempool_free(rq, q->rq.rq_pool);
 }
 
 static struct request *
-blk_alloc_request(struct request_queue *q, unsigned int flags, gfp_t gfp_mask)
+blk_alloc_request(struct request_queue *q, struct io_cq *icq,
+		  unsigned int flags, gfp_t gfp_mask)
 {
 	struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask);
 
@@ -635,10 +661,15 @@ blk_alloc_request(struct request_queue *q, unsigned int flags, gfp_t gfp_mask)
 
 	rq->cmd_flags = flags | REQ_ALLOCED;
 
-	if ((flags & REQ_ELVPRIV) &&
-	    unlikely(elv_set_request(q, rq, gfp_mask))) {
-		mempool_free(rq, q->rq.rq_pool);
-		return NULL;
+	if (flags & REQ_ELVPRIV) {
+		rq->elv.icq = icq;
+		if (unlikely(elv_set_request(q, rq, gfp_mask))) {
+			mempool_free(rq, q->rq.rq_pool);
+			return NULL;
+		}
+		/* @rq->elv.icq holds on to io_context until @rq is freed */
+		if (icq)
+			get_io_context(icq->ioc);
 	}
 
 	return rq;
@@ -750,11 +781,17 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
 {
 	struct request *rq = NULL;
 	struct request_list *rl = &q->rq;
-	struct io_context *ioc = NULL;
+	struct elevator_type *et;
+	struct io_context *ioc;
+	struct io_cq *icq = NULL;
 	const bool is_sync = rw_is_sync(rw_flags) != 0;
+	bool retried = false;
 	int may_queue;
+retry:
+	et = q->elevator->type;
+	ioc = current->io_context;
 
-	if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
+	if (unlikely(blk_queue_dead(q)))
 		return NULL;
 
 	may_queue = elv_may_queue(q, rw_flags);
@@ -763,7 +800,20 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
 
 	if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) {
 		if (rl->count[is_sync]+1 >= q->nr_requests) {
-			ioc = current_io_context(GFP_ATOMIC, q->node);
+			/*
+			 * We want ioc to record batching state.  If it's
+			 * not already there, creating a new one requires
+			 * dropping queue_lock, which in turn requires
+			 * retesting conditions to avoid queue hang.
+			 */
+			if (!ioc && !retried) {
+				spin_unlock_irq(q->queue_lock);
+				create_io_context(current, gfp_mask, q->node);
+				spin_lock_irq(q->queue_lock);
+				retried = true;
+				goto retry;
+			}
+
 			/*
 			 * The queue will fill after this allocation, so set
 			 * it as full, and mark this process as "batching".
@@ -799,17 +849,36 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
 	rl->count[is_sync]++;
 	rl->starved[is_sync] = 0;
 
+	/*
+	 * Decide whether the new request will be managed by elevator.  If
+	 * so, mark @rw_flags and increment elvpriv.  Non-zero elvpriv will
+	 * prevent the current elevator from being destroyed until the new
+	 * request is freed.  This guarantees icq's won't be destroyed and
+	 * makes creating new ones safe.
+	 *
+	 * Also, lookup icq while holding queue_lock.  If it doesn't exist,
+	 * it will be created after releasing queue_lock.
+	 */
 	if (blk_rq_should_init_elevator(bio) &&
 	    !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags)) {
 		rw_flags |= REQ_ELVPRIV;
 		rl->elvpriv++;
+		if (et->icq_cache && ioc)
+			icq = ioc_lookup_icq(ioc, q);
 	}
 
 	if (blk_queue_io_stat(q))
 		rw_flags |= REQ_IO_STAT;
 	spin_unlock_irq(q->queue_lock);
 
-	rq = blk_alloc_request(q, rw_flags, gfp_mask);
+	/* create icq if missing */
+	if (unlikely(et->icq_cache && !icq))
+		icq = ioc_create_icq(q, gfp_mask);
+
+	/* rqs are guaranteed to have icq on elv_set_request() if requested */
+	if (likely(!et->icq_cache || icq))
+		rq = blk_alloc_request(q, icq, rw_flags, gfp_mask);
+
 	if (unlikely(!rq)) {
 		/*
 		 * Allocation failed presumably due to memory. Undo anything
@@ -871,10 +940,9 @@ static struct request *get_request_wait(struct request_queue *q, int rw_flags,
 	rq = get_request(q, rw_flags, bio, GFP_NOIO);
 	while (!rq) {
 		DEFINE_WAIT(wait);
-		struct io_context *ioc;
 		struct request_list *rl = &q->rq;
 
-		if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
+		if (unlikely(blk_queue_dead(q)))
 			return NULL;
 
 		prepare_to_wait_exclusive(&rl->wait[is_sync], &wait,
@@ -891,8 +959,8 @@ static struct request *get_request_wait(struct request_queue *q, int rw_flags,
 		 * up to a big batch of them for a small period time.
 		 * See ioc_batching, ioc_set_batching
 		 */
-		ioc = current_io_context(GFP_NOIO, q->node);
-		ioc_set_batching(q, ioc);
+		create_io_context(current, GFP_NOIO, q->node);
+		ioc_set_batching(q, current->io_context);
 
 		spin_lock_irq(q->queue_lock);
 		finish_wait(&rl->wait[is_sync], &wait);
@@ -1009,54 +1077,6 @@ static void add_acct_request(struct request_queue *q, struct request *rq,
 	__elv_add_request(q, rq, where);
 }
 
-/**
- * blk_insert_request - insert a special request into a request queue
- * @q:		request queue where request should be inserted
- * @rq:		request to be inserted
- * @at_head:	insert request at head or tail of queue
- * @data:	private data
- *
- * Description:
- *    Many block devices need to execute commands asynchronously, so they don't
- *    block the whole kernel from preemption during request execution.  This is
- *    accomplished normally by inserting aritficial requests tagged as
- *    REQ_TYPE_SPECIAL in to the corresponding request queue, and letting them
- *    be scheduled for actual execution by the request queue.
- *
- *    We have the option of inserting the head or the tail of the queue.
- *    Typically we use the tail for new ioctls and so forth.  We use the head
- *    of the queue for things like a QUEUE_FULL message from a device, or a
- *    host that is unable to accept a particular command.
- */
-void blk_insert_request(struct request_queue *q, struct request *rq,
-			int at_head, void *data)
-{
-	int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
-	unsigned long flags;
-
-	/*
-	 * tell I/O scheduler that this isn't a regular read/write (ie it
-	 * must not attempt merges on this) and that it acts as a soft
-	 * barrier
-	 */
-	rq->cmd_type = REQ_TYPE_SPECIAL;
-
-	rq->special = data;
-
-	spin_lock_irqsave(q->queue_lock, flags);
-
-	/*
-	 * If command is tagged, release the tag
-	 */
-	if (blk_rq_tagged(rq))
-		blk_queue_end_tag(q, rq);
-
-	add_acct_request(q, rq, where);
-	__blk_run_queue(q);
-	spin_unlock_irqrestore(q->queue_lock, flags);
-}
-EXPORT_SYMBOL(blk_insert_request);
-
 static void part_round_stats_single(int cpu, struct hd_struct *part,
 				    unsigned long now)
 {
@@ -1766,6 +1786,10 @@ int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
 		return -EIO;
 
 	spin_lock_irqsave(q->queue_lock, flags);
+	if (unlikely(blk_queue_dead(q))) {
+		spin_unlock_irqrestore(q->queue_lock, flags);
+		return -ENODEV;
+	}
 
 	/*
 	 * Submitting request must be dequeued before calling this function
@@ -2740,6 +2764,14 @@ static void queue_unplugged(struct request_queue *q, unsigned int depth,
 	trace_block_unplug(q, depth, !from_schedule);
 
 	/*
+	 * Don't mess with dead queue.
+	 */
+	if (unlikely(blk_queue_dead(q))) {
+		spin_unlock(q->queue_lock);
+		return;
+	}
+
+	/*
 	 * If we are punting this to kblockd, then we can safely drop
 	 * the queue_lock before waking kblockd (which needs to take
 	 * this lock).
@@ -2815,6 +2847,15 @@ void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
 			depth = 0;
 			spin_lock(q->queue_lock);
 		}
+
+		/*
+		 * Short-circuit if @q is dead
+		 */
+		if (unlikely(blk_queue_dead(q))) {
+			__blk_end_request_all(rq, -ENODEV);
+			continue;
+		}
+
 		/*
 		 * rq is already accounted, so use raw insert
 		 */
diff --git a/block/blk-exec.c b/block/blk-exec.c
index a1ebceb..fb2cbd5 100644
--- a/block/blk-exec.c
+++ b/block/blk-exec.c
@@ -50,7 +50,11 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
 {
 	int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
 
-	if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
+	WARN_ON(irqs_disabled());
+	spin_lock_irq(q->queue_lock);
+
+	if (unlikely(blk_queue_dead(q))) {
+		spin_unlock_irq(q->queue_lock);
 		rq->errors = -ENXIO;
 		if (rq->end_io)
 			rq->end_io(rq, rq->errors);
@@ -59,8 +63,6 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
 
 	rq->rq_disk = bd_disk;
 	rq->end_io = done;
-	WARN_ON(irqs_disabled());
-	spin_lock_irq(q->queue_lock);
 	__elv_add_request(q, rq, where);
 	__blk_run_queue(q);
 	/* the queue is stopped so it won't be run */
diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index 6f9bbd9..27a06e0 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -16,53 +16,214 @@
  */
 static struct kmem_cache *iocontext_cachep;
 
-static void cfq_dtor(struct io_context *ioc)
+/**
+ * get_io_context - increment reference count to io_context
+ * @ioc: io_context to get
+ *
+ * Increment reference count to @ioc.
+ */
+void get_io_context(struct io_context *ioc)
+{
+	BUG_ON(atomic_long_read(&ioc->refcount) <= 0);
+	atomic_long_inc(&ioc->refcount);
+}
+EXPORT_SYMBOL(get_io_context);
+
+/*
+ * Releasing ioc may nest into another put_io_context() leading to nested
+ * fast path release.  As the ioc's can't be the same, this is okay but
+ * makes lockdep whine.  Keep track of nesting and use it as subclass.
+ */
+#ifdef CONFIG_LOCKDEP
+#define ioc_release_depth(q)		((q) ? (q)->ioc_release_depth : 0)
+#define ioc_release_depth_inc(q)	(q)->ioc_release_depth++
+#define ioc_release_depth_dec(q)	(q)->ioc_release_depth--
+#else
+#define ioc_release_depth(q)		0
+#define ioc_release_depth_inc(q)	do { } while (0)
+#define ioc_release_depth_dec(q)	do { } while (0)
+#endif
+
+static void icq_free_icq_rcu(struct rcu_head *head)
+{
+	struct io_cq *icq = container_of(head, struct io_cq, __rcu_head);
+
+	kmem_cache_free(icq->__rcu_icq_cache, icq);
+}
+
+/*
+ * Exit and free an icq.  Called with both ioc and q locked.
+ */
+static void ioc_exit_icq(struct io_cq *icq)
 {
-	if (!hlist_empty(&ioc->cic_list)) {
-		struct cfq_io_context *cic;
+	struct io_context *ioc = icq->ioc;
+	struct request_queue *q = icq->q;
+	struct elevator_type *et = q->elevator->type;
+
+	lockdep_assert_held(&ioc->lock);
+	lockdep_assert_held(q->queue_lock);
+
+	radix_tree_delete(&ioc->icq_tree, icq->q->id);
+	hlist_del_init(&icq->ioc_node);
+	list_del_init(&icq->q_node);
+
+	/*
+	 * Both setting lookup hint to and clearing it from @icq are done
+	 * under queue_lock.  If it's not pointing to @icq now, it never
+	 * will.  Hint assignment itself can race safely.
+	 */
+	if (rcu_dereference_raw(ioc->icq_hint) == icq)
+		rcu_assign_pointer(ioc->icq_hint, NULL);
 
-		cic = hlist_entry(ioc->cic_list.first, struct cfq_io_context,
-								cic_list);
-		cic->dtor(ioc);
+	if (et->ops.elevator_exit_icq_fn) {
+		ioc_release_depth_inc(q);
+		et->ops.elevator_exit_icq_fn(icq);
+		ioc_release_depth_dec(q);
 	}
+
+	/*
+	 * @icq->q might have gone away by the time RCU callback runs
+	 * making it impossible to determine icq_cache.  Record it in @icq.
+	 */
+	icq->__rcu_icq_cache = et->icq_cache;
+	call_rcu(&icq->__rcu_head, icq_free_icq_rcu);
 }
 
 /*
- * IO Context helper functions. put_io_context() returns 1 if there are no
- * more users of this io context, 0 otherwise.
+ * Slow path for ioc release in put_io_context().  Performs double-lock
+ * dancing to unlink all icq's and then frees ioc.
  */
-int put_io_context(struct io_context *ioc)
+static void ioc_release_fn(struct work_struct *work)
 {
-	if (ioc == NULL)
-		return 1;
+	struct io_context *ioc = container_of(work, struct io_context,
+					      release_work);
+	struct request_queue *last_q = NULL;
 
-	BUG_ON(atomic_long_read(&ioc->refcount) == 0);
+	spin_lock_irq(&ioc->lock);
 
-	if (atomic_long_dec_and_test(&ioc->refcount)) {
-		rcu_read_lock();
-		cfq_dtor(ioc);
-		rcu_read_unlock();
+	while (!hlist_empty(&ioc->icq_list)) {
+		struct io_cq *icq = hlist_entry(ioc->icq_list.first,
+						struct io_cq, ioc_node);
+		struct request_queue *this_q = icq->q;
 
-		kmem_cache_free(iocontext_cachep, ioc);
-		return 1;
+		if (this_q != last_q) {
+			/*
+			 * Need to switch to @this_q.  Once we release
+			 * @ioc->lock, it can go away along with @cic.
+			 * Hold on to it.
+			 */
+			__blk_get_queue(this_q);
+
+			/*
+			 * blk_put_queue() might sleep thanks to kobject
+			 * idiocy.  Always release both locks, put and
+			 * restart.
+			 */
+			if (last_q) {
+				spin_unlock(last_q->queue_lock);
+				spin_unlock_irq(&ioc->lock);
+				blk_put_queue(last_q);
+			} else {
+				spin_unlock_irq(&ioc->lock);
+			}
+
+			last_q = this_q;
+			spin_lock_irq(this_q->queue_lock);
+			spin_lock(&ioc->lock);
+			continue;
+		}
+		ioc_exit_icq(icq);
 	}
-	return 0;
+
+	if (last_q) {
+		spin_unlock(last_q->queue_lock);
+		spin_unlock_irq(&ioc->lock);
+		blk_put_queue(last_q);
+	} else {
+		spin_unlock_irq(&ioc->lock);
+	}
+
+	kmem_cache_free(iocontext_cachep, ioc);
 }
-EXPORT_SYMBOL(put_io_context);
 
-static void cfq_exit(struct io_context *ioc)
+/**
+ * put_io_context - put a reference of io_context
+ * @ioc: io_context to put
+ * @locked_q: request_queue the caller is holding queue_lock of (hint)
+ *
+ * Decrement reference count of @ioc and release it if the count reaches
+ * zero.  If the caller is holding queue_lock of a queue, it can indicate
+ * that with @locked_q.  This is an optimization hint and the caller is
+ * allowed to pass in %NULL even when it's holding a queue_lock.
+ */
+void put_io_context(struct io_context *ioc, struct request_queue *locked_q)
 {
-	rcu_read_lock();
+	struct request_queue *last_q = locked_q;
+	unsigned long flags;
+
+	if (ioc == NULL)
+		return;
+
+	BUG_ON(atomic_long_read(&ioc->refcount) <= 0);
+	if (locked_q)
+		lockdep_assert_held(locked_q->queue_lock);
 
-	if (!hlist_empty(&ioc->cic_list)) {
-		struct cfq_io_context *cic;
+	if (!atomic_long_dec_and_test(&ioc->refcount))
+		return;
+
+	/*
+	 * Destroy @ioc.  This is a bit messy because icq's are chained
+	 * from both ioc and queue, and ioc->lock nests inside queue_lock.
+	 * The inner ioc->lock should be held to walk our icq_list and then
+	 * for each icq the outer matching queue_lock should be grabbed.
+	 * ie. We need to do reverse-order double lock dancing.
+	 *
+	 * Another twist is that we are often called with one of the
+	 * matching queue_locks held as indicated by @locked_q, which
+	 * prevents performing double-lock dance for other queues.
+	 *
+	 * So, we do it in two stages.  The fast path uses the queue_lock
+	 * the caller is holding and, if other queues need to be accessed,
+	 * uses trylock to avoid introducing locking dependency.  This can
+	 * handle most cases, especially if @ioc was performing IO on only
+	 * single device.
+	 *
+	 * If trylock doesn't cut it, we defer to @ioc->release_work which
+	 * can do all the double-locking dancing.
+	 */
+	spin_lock_irqsave_nested(&ioc->lock, flags,
+				 ioc_release_depth(locked_q));
 
-		cic = hlist_entry(ioc->cic_list.first, struct cfq_io_context,
-								cic_list);
-		cic->exit(ioc);
+	while (!hlist_empty(&ioc->icq_list)) {
+		struct io_cq *icq = hlist_entry(ioc->icq_list.first,
+						struct io_cq, ioc_node);
+		struct request_queue *this_q = icq->q;
+
+		if (this_q != last_q) {
+			if (last_q && last_q != locked_q)
+				spin_unlock(last_q->queue_lock);
+			last_q = NULL;
+
+			if (!spin_trylock(this_q->queue_lock))
+				break;
+			last_q = this_q;
+			continue;
+		}
+		ioc_exit_icq(icq);
 	}
-	rcu_read_unlock();
+
+	if (last_q && last_q != locked_q)
+		spin_unlock(last_q->queue_lock);
+
+	spin_unlock_irqrestore(&ioc->lock, flags);
+
+	/* if no icq is left, we're done; otherwise, kick release_work */
+	if (hlist_empty(&ioc->icq_list))
+		kmem_cache_free(iocontext_cachep, ioc);
+	else
+		schedule_work(&ioc->release_work);
 }
+EXPORT_SYMBOL(put_io_context);
 
 /* Called by the exiting task */
 void exit_io_context(struct task_struct *task)
@@ -74,86 +235,240 @@ void exit_io_context(struct task_struct *task)
 	task->io_context = NULL;
 	task_unlock(task);
 
-	if (atomic_dec_and_test(&ioc->nr_tasks))
-		cfq_exit(ioc);
+	atomic_dec(&ioc->nr_tasks);
+	put_io_context(ioc, NULL);
+}
+
+/**
+ * ioc_clear_queue - break any ioc association with the specified queue
+ * @q: request_queue being cleared
+ *
+ * Walk @q->icq_list and exit all io_cq's.  Must be called with @q locked.
+ */
+void ioc_clear_queue(struct request_queue *q)
+{
+	lockdep_assert_held(q->queue_lock);
+
+	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;
 
-	put_io_context(ioc);
+		spin_lock(&ioc->lock);
+		ioc_exit_icq(icq);
+		spin_unlock(&ioc->lock);
+	}
 }
 
-struct io_context *alloc_io_context(gfp_t gfp_flags, int node)
+void create_io_context_slowpath(struct task_struct *task, gfp_t gfp_flags,
+				int node)
 {
 	struct io_context *ioc;
 
-	ioc = kmem_cache_alloc_node(iocontext_cachep, gfp_flags, node);
-	if (ioc) {
-		atomic_long_set(&ioc->refcount, 1);
-		atomic_set(&ioc->nr_tasks, 1);
-		spin_lock_init(&ioc->lock);
-		ioc->ioprio_changed = 0;
-		ioc->ioprio = 0;
-		ioc->last_waited = 0; /* doesn't matter... */
-		ioc->nr_batch_requests = 0; /* because this is 0 */
-		INIT_RADIX_TREE(&ioc->radix_root, GFP_ATOMIC | __GFP_HIGH);
-		INIT_HLIST_HEAD(&ioc->cic_list);
-		ioc->ioc_data = NULL;
-#if defined(CONFIG_BLK_CGROUP) || defined(CONFIG_BLK_CGROUP_MODULE)
-		ioc->cgroup_changed = 0;
-#endif
-	}
+	ioc = kmem_cache_alloc_node(iocontext_cachep, gfp_flags | __GFP_ZERO,
+				    node);
+	if (unlikely(!ioc))
+		return;
 
-	return ioc;
+	/* initialize */
+	atomic_long_set(&ioc->refcount, 1);
+	atomic_set(&ioc->nr_tasks, 1);
+	spin_lock_init(&ioc->lock);
+	INIT_RADIX_TREE(&ioc->icq_tree, GFP_ATOMIC | __GFP_HIGH);
+	INIT_HLIST_HEAD(&ioc->icq_list);
+	INIT_WORK(&ioc->release_work, ioc_release_fn);
+
+	/*
+	 * Try to install.  ioc shouldn't be installed if someone else
+	 * already did or @task, which isn't %current, is exiting.  Note
+	 * that we need to allow ioc creation on exiting %current as exit
+	 * path may issue IOs from e.g. exit_files().  The exit path is
+	 * responsible for not issuing IO after exit_io_context().
+	 */
+	task_lock(task);
+	if (!task->io_context &&
+	    (task == current || !(task->flags & PF_EXITING)))
+		task->io_context = ioc;
+	else
+		kmem_cache_free(iocontext_cachep, ioc);
+	task_unlock(task);
 }
 
-/*
- * If the current task has no IO context then create one and initialise it.
- * Otherwise, return its existing IO context.
+/**
+ * get_task_io_context - get io_context of a task
+ * @task: task of interest
+ * @gfp_flags: allocation flags, used if allocation is necessary
+ * @node: allocation node, used if allocation is necessary
  *
- * This returned IO context doesn't have a specifically elevated refcount,
- * but since the current task itself holds a reference, the context can be
- * used in general code, so long as it stays within `current` context.
+ * Return io_context of @task.  If it doesn't exist, it is created with
+ * @gfp_flags and @node.  The returned io_context has its reference count
+ * incremented.
+ *
+ * This function always goes through task_lock() and it's better to use
+ * %current->io_context + get_io_context() for %current.
  */
-struct io_context *current_io_context(gfp_t gfp_flags, int node)
+struct io_context *get_task_io_context(struct task_struct *task,
+				       gfp_t gfp_flags, int node)
 {
-	struct task_struct *tsk = current;
-	struct io_context *ret;
-
-	ret = tsk->io_context;
-	if (likely(ret))
-		return ret;
-
-	ret = alloc_io_context(gfp_flags, node);
-	if (ret) {
-		/* make sure set_task_ioprio() sees the settings above */
-		smp_wmb();
-		tsk->io_context = ret;
-	}
+	struct io_context *ioc;
 
-	return ret;
+	might_sleep_if(gfp_flags & __GFP_WAIT);
+
+	do {
+		task_lock(task);
+		ioc = task->io_context;
+		if (likely(ioc)) {
+			get_io_context(ioc);
+			task_unlock(task);
+			return ioc;
+		}
+		task_unlock(task);
+	} while (create_io_context(task, gfp_flags, node));
+
+	return NULL;
 }
+EXPORT_SYMBOL(get_task_io_context);
 
-/*
- * If the current task has no IO context then create one and initialise it.
- * If it does have a context, take a ref on it.
+/**
+ * ioc_lookup_icq - lookup io_cq from ioc
+ * @ioc: the associated io_context
+ * @q: the associated request_queue
  *
- * This is always called in the context of the task which submitted the I/O.
+ * Look up io_cq associated with @ioc - @q pair from @ioc.  Must be called
+ * with @q->queue_lock held.
  */
-struct io_context *get_io_context(gfp_t gfp_flags, int node)
+struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q)
 {
-	struct io_context *ioc = NULL;
+	struct io_cq *icq;
+
+	lockdep_assert_held(q->queue_lock);
 
 	/*
-	 * Check for unlikely race with exiting task. ioc ref count is
-	 * zero when ioc is being detached.
+	 * icq's are indexed from @ioc using radix tree and hint pointer,
+	 * both of which are protected with RCU.  All removals are done
+	 * holding both q and ioc locks, and we're holding q lock - if we
+	 * find a icq which points to us, it's guaranteed to be valid.
 	 */
-	do {
-		ioc = current_io_context(gfp_flags, node);
-		if (unlikely(!ioc))
-			break;
-	} while (!atomic_long_inc_not_zero(&ioc->refcount));
+	rcu_read_lock();
+	icq = rcu_dereference(ioc->icq_hint);
+	if (icq && icq->q == q)
+		goto out;
 
-	return ioc;
+	icq = radix_tree_lookup(&ioc->icq_tree, q->id);
+	if (icq && icq->q == q)
+		rcu_assign_pointer(ioc->icq_hint, icq);	/* allowed to race */
+	else
+		icq = NULL;
+out:
+	rcu_read_unlock();
+	return icq;
 }
-EXPORT_SYMBOL(get_io_context);
+EXPORT_SYMBOL(ioc_lookup_icq);
+
+/**
+ * ioc_create_icq - create and link io_cq
+ * @q: request_queue of interest
+ * @gfp_mask: allocation mask
+ *
+ * Make sure io_cq linking %current->io_context and @q exists.  If either
+ * io_context and/or icq don't exist, they will be created using @gfp_mask.
+ *
+ * The caller is responsible for ensuring @ioc won't go away and @q is
+ * alive and will stay alive until this function returns.
+ */
+struct io_cq *ioc_create_icq(struct request_queue *q, gfp_t gfp_mask)
+{
+	struct elevator_type *et = q->elevator->type;
+	struct io_context *ioc;
+	struct io_cq *icq;
+
+	/* allocate stuff */
+	ioc = create_io_context(current, gfp_mask, q->node);
+	if (!ioc)
+		return NULL;
+
+	icq = kmem_cache_alloc_node(et->icq_cache, gfp_mask | __GFP_ZERO,
+				    q->node);
+	if (!icq)
+		return NULL;
+
+	if (radix_tree_preload(gfp_mask) < 0) {
+		kmem_cache_free(et->icq_cache, icq);
+		return NULL;
+	}
+
+	icq->ioc = ioc;
+	icq->q = q;
+	INIT_LIST_HEAD(&icq->q_node);
+	INIT_HLIST_NODE(&icq->ioc_node);
+
+	/* lock both q and ioc and try to link @icq */
+	spin_lock_irq(q->queue_lock);
+	spin_lock(&ioc->lock);
+
+	if (likely(!radix_tree_insert(&ioc->icq_tree, q->id, icq))) {
+		hlist_add_head(&icq->ioc_node, &ioc->icq_list);
+		list_add(&icq->q_node, &q->icq_list);
+		if (et->ops.elevator_init_icq_fn)
+			et->ops.elevator_init_icq_fn(icq);
+	} else {
+		kmem_cache_free(et->icq_cache, icq);
+		icq = ioc_lookup_icq(ioc, q);
+		if (!icq)
+			printk(KERN_ERR "cfq: icq link failed!\n");
+	}
+
+	spin_unlock(&ioc->lock);
+	spin_unlock_irq(q->queue_lock);
+	radix_tree_preload_end();
+	return icq;
+}
+
+void ioc_set_changed(struct io_context *ioc, int which)
+{
+	struct io_cq *icq;
+	struct hlist_node *n;
+
+	hlist_for_each_entry(icq, n, &ioc->icq_list, ioc_node)
+		set_bit(which, &icq->changed);
+}
+
+/**
+ * ioc_ioprio_changed - notify ioprio change
+ * @ioc: io_context of interest
+ * @ioprio: new ioprio
+ *
+ * @ioc's ioprio has changed to @ioprio.  Set %ICQ_IOPRIO_CHANGED for all
+ * icq's.  iosched is responsible for checking the bit and applying it on
+ * request issue path.
+ */
+void ioc_ioprio_changed(struct io_context *ioc, int ioprio)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ioc->lock, flags);
+	ioc->ioprio = ioprio;
+	ioc_set_changed(ioc, ICQ_IOPRIO_CHANGED);
+	spin_unlock_irqrestore(&ioc->lock, flags);
+}
+
+/**
+ * ioc_cgroup_changed - notify cgroup change
+ * @ioc: io_context of interest
+ *
+ * @ioc's cgroup has changed.  Set %ICQ_CGROUP_CHANGED for all icq's.
+ * iosched is responsible for checking the bit and applying it on request
+ * issue path.
+ */
+void ioc_cgroup_changed(struct io_context *ioc)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ioc->lock, flags);
+	ioc_set_changed(ioc, ICQ_CGROUP_CHANGED);
+	spin_unlock_irqrestore(&ioc->lock, flags);
+}
+EXPORT_SYMBOL(ioc_cgroup_changed);
 
 static int __init blk_ioc_init(void)
 {
diff --git a/block/blk-settings.c b/block/blk-settings.c
index fa1eb04..d3234fc 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -104,9 +104,7 @@ EXPORT_SYMBOL_GPL(blk_queue_lld_busy);
  * @lim:  the queue_limits structure to reset
  *
  * Description:
- *   Returns a queue_limit struct to its default state.  Can be used by
- *   stacking drivers like DM that stage table swaps and reuse an
- *   existing device queue.
+ *   Returns a queue_limit struct to its default state.
  */
 void blk_set_default_limits(struct queue_limits *lim)
 {
@@ -114,13 +112,12 @@ void blk_set_default_limits(struct queue_limits *lim)
 	lim->max_integrity_segments = 0;
 	lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
 	lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
-	lim->max_sectors = BLK_DEF_MAX_SECTORS;
-	lim->max_hw_sectors = INT_MAX;
+	lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;
 	lim->max_discard_sectors = 0;
 	lim->discard_granularity = 0;
 	lim->discard_alignment = 0;
 	lim->discard_misaligned = 0;
-	lim->discard_zeroes_data = 1;
+	lim->discard_zeroes_data = 0;
 	lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
 	lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT);
 	lim->alignment_offset = 0;
@@ -131,6 +128,27 @@ void blk_set_default_limits(struct queue_limits *lim)
 EXPORT_SYMBOL(blk_set_default_limits);
 
 /**
+ * blk_set_stacking_limits - set default limits for stacking devices
+ * @lim:  the queue_limits structure to reset
+ *
+ * Description:
+ *   Returns a queue_limit struct to its default state. Should be used
+ *   by stacking drivers like DM that have no internal limits.
+ */
+void blk_set_stacking_limits(struct queue_limits *lim)
+{
+	blk_set_default_limits(lim);
+
+	/* Inherit limits from component devices */
+	lim->discard_zeroes_data = 1;
+	lim->max_segments = USHRT_MAX;
+	lim->max_hw_sectors = UINT_MAX;
+
+	lim->max_sectors = BLK_DEF_MAX_SECTORS;
+}
+EXPORT_SYMBOL(blk_set_stacking_limits);
+
+/**
  * blk_queue_make_request - define an alternate make_request function for a device
  * @q:  the request queue for the device to be affected
  * @mfn: the alternate make_request function
@@ -165,8 +183,6 @@ void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)
 	q->nr_batching = BLK_BATCH_REQ;
 
 	blk_set_default_limits(&q->limits);
-	blk_queue_max_hw_sectors(q, BLK_SAFE_MAX_SECTORS);
-	q->limits.discard_zeroes_data = 0;
 
 	/*
 	 * by default assume old behaviour and bounce for any highmem page
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index e7f9f65..cf15001 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -425,7 +425,7 @@ queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 	if (!entry->show)
 		return -EIO;
 	mutex_lock(&q->sysfs_lock);
-	if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
+	if (blk_queue_dead(q)) {
 		mutex_unlock(&q->sysfs_lock);
 		return -ENOENT;
 	}
@@ -447,7 +447,7 @@ queue_attr_store(struct kobject *kobj, struct attribute *attr,
 
 	q = container_of(kobj, struct request_queue, kobj);
 	mutex_lock(&q->sysfs_lock);
-	if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
+	if (blk_queue_dead(q)) {
 		mutex_unlock(&q->sysfs_lock);
 		return -ENOENT;
 	}
@@ -479,8 +479,12 @@ static void blk_release_queue(struct kobject *kobj)
 
 	blk_sync_queue(q);
 
-	if (q->elevator)
+	if (q->elevator) {
+		spin_lock_irq(q->queue_lock);
+		ioc_clear_queue(q);
+		spin_unlock_irq(q->queue_lock);
 		elevator_exit(q->elevator);
+	}
 
 	blk_throtl_exit(q);
 
@@ -494,6 +498,8 @@ static void blk_release_queue(struct kobject *kobj)
 	blk_trace_shutdown(q);
 
 	bdi_destroy(&q->backing_dev_info);
+
+	ida_simple_remove(&blk_queue_ida, q->id);
 	kmem_cache_free(blk_requestq_cachep, q);
 }
 
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 4553245..5eed6a7 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -310,7 +310,7 @@ static struct throtl_grp * throtl_get_tg(struct throtl_data *td)
 	struct request_queue *q = td->queue;
 
 	/* no throttling for dead queue */
-	if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
+	if (unlikely(blk_queue_dead(q)))
 		return NULL;
 
 	rcu_read_lock();
@@ -335,7 +335,7 @@ static struct throtl_grp * throtl_get_tg(struct throtl_data *td)
 	spin_lock_irq(q->queue_lock);
 
 	/* Make sure @q is still alive */
-	if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
+	if (unlikely(blk_queue_dead(q))) {
 		kfree(tg);
 		return NULL;
 	}
diff --git a/block/blk.h b/block/blk.h
index 3f6551b..7efd772 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -1,6 +1,8 @@
 #ifndef BLK_INTERNAL_H
 #define BLK_INTERNAL_H
 
+#include <linux/idr.h>
+
 /* Amount of time in which a process may batch requests */
 #define BLK_BATCH_TIME	(HZ/50UL)
 
@@ -9,6 +11,12 @@
 
 extern struct kmem_cache *blk_requestq_cachep;
 extern struct kobj_type blk_queue_ktype;
+extern struct ida blk_queue_ida;
+
+static inline void __blk_get_queue(struct request_queue *q)
+{
+	kobject_get(&q->kobj);
+}
 
 void init_request_from_bio(struct request *req, struct bio *bio);
 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
@@ -85,8 +93,8 @@ static inline struct request *__elv_next_request(struct request_queue *q)
 			q->flush_queue_delayed = 1;
 			return NULL;
 		}
-		if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags) ||
-		    !q->elevator->ops->elevator_dispatch_fn(q, 0))
+		if (unlikely(blk_queue_dead(q)) ||
+		    !q->elevator->type->ops.elevator_dispatch_fn(q, 0))
 			return NULL;
 	}
 }
@@ -95,16 +103,16 @@ static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
 {
 	struct elevator_queue *e = q->elevator;
 
-	if (e->ops->elevator_activate_req_fn)
-		e->ops->elevator_activate_req_fn(q, rq);
+	if (e->type->ops.elevator_activate_req_fn)
+		e->type->ops.elevator_activate_req_fn(q, rq);
 }
 
 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
 {
 	struct elevator_queue *e = q->elevator;
 
-	if (e->ops->elevator_deactivate_req_fn)
-		e->ops->elevator_deactivate_req_fn(q, rq);
+	if (e->type->ops.elevator_deactivate_req_fn)
+		e->type->ops.elevator_deactivate_req_fn(q, rq);
 }
 
 #ifdef CONFIG_FAIL_IO_TIMEOUT
@@ -119,8 +127,6 @@ static inline int blk_should_fake_timeout(struct request_queue *q)
 }
 #endif
 
-struct io_context *current_io_context(gfp_t gfp_flags, int node);
-
 int ll_back_merge_fn(struct request_queue *q, struct request *req,
 		     struct bio *bio);
 int ll_front_merge_fn(struct request_queue *q, struct request *req, 
@@ -189,6 +195,42 @@ static inline int blk_do_io_stat(struct request *rq)
 	        (rq->cmd_flags & REQ_DISCARD));
 }
 
+/*
+ * Internal io_context interface
+ */
+void get_io_context(struct io_context *ioc);
+struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q);
+struct io_cq *ioc_create_icq(struct request_queue *q, gfp_t gfp_mask);
+void ioc_clear_queue(struct request_queue *q);
+
+void create_io_context_slowpath(struct task_struct *task, gfp_t gfp_mask,
+				int node);
+
+/**
+ * create_io_context - try to create task->io_context
+ * @task: target task
+ * @gfp_mask: allocation mask
+ * @node: allocation node
+ *
+ * If @task->io_context is %NULL, allocate a new io_context and install it.
+ * Returns the current @task->io_context which may be %NULL if allocation
+ * failed.
+ *
+ * Note that this function can't be called with IRQ disabled because
+ * task_lock which protects @task->io_context is IRQ-unsafe.
+ */
+static inline struct io_context *create_io_context(struct task_struct *task,
+						   gfp_t gfp_mask, int node)
+{
+	WARN_ON_ONCE(irqs_disabled());
+	if (unlikely(!task->io_context))
+		create_io_context_slowpath(task, gfp_mask, node);
+	return task->io_context;
+}
+
+/*
+ * Internal throttling interface
+ */
 #ifdef CONFIG_BLK_DEV_THROTTLING
 extern bool blk_throtl_bio(struct request_queue *q, struct bio *bio);
 extern void blk_throtl_drain(struct request_queue *q);
diff --git a/block/bsg.c b/block/bsg.c
index 9651ec7..4cf703f 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -769,12 +769,10 @@ static struct bsg_device *bsg_add_device(struct inode *inode,
 					 struct file *file)
 {
 	struct bsg_device *bd;
-	int ret;
 #ifdef BSG_DEBUG
 	unsigned char buf[32];
 #endif
-	ret = blk_get_queue(rq);
-	if (ret)
+	if (!blk_get_queue(rq))
 		return ERR_PTR(-ENXIO);
 
 	bd = bsg_alloc_device();
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 3548705..163263d 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -14,6 +14,7 @@
 #include <linux/rbtree.h>
 #include <linux/ioprio.h>
 #include <linux/blktrace_api.h>
+#include "blk.h"
 #include "cfq.h"
 
 /*
@@ -53,20 +54,11 @@ 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)		\
-	((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])
+#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_ioc_pool;
-
-static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
-static struct completion *ioc_gone;
-static DEFINE_SPINLOCK(ioc_gone_lock);
-
-static DEFINE_SPINLOCK(cic_index_lock);
-static DEFINE_IDA(cic_index_ida);
 
 #define CFQ_PRIO_LISTS		IOPRIO_BE_NR
 #define cfq_class_idle(cfqq)	((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
@@ -75,6 +67,14 @@ static DEFINE_IDA(cic_index_ida);
 #define sample_valid(samples)	((samples) > 80)
 #define rb_entry_cfqg(node)	rb_entry((node), struct cfq_group, rb_node)
 
+struct cfq_ttime {
+	unsigned long last_end_request;
+
+	unsigned long ttime_total;
+	unsigned long ttime_samples;
+	unsigned long ttime_mean;
+};
+
 /*
  * Most of our rbtree usage is for sorting with min extraction, so
  * if we cache the leftmost node we don't have to walk down the tree
@@ -216,6 +216,12 @@ struct cfq_group {
 	struct cfq_ttime ttime;
 };
 
+struct cfq_io_cq {
+	struct io_cq		icq;		/* must be the first member */
+	struct cfq_queue	*cfqq[2];
+	struct cfq_ttime	ttime;
+};
+
 /*
  * Per block device queue structure
  */
@@ -267,7 +273,7 @@ struct cfq_data {
 	struct work_struct unplug_work;
 
 	struct cfq_queue *active_queue;
-	struct cfq_io_context *active_cic;
+	struct cfq_io_cq *active_cic;
 
 	/*
 	 * async queue for each priority case
@@ -290,9 +296,6 @@ struct cfq_data {
 	unsigned int cfq_group_idle;
 	unsigned int cfq_latency;
 
-	unsigned int cic_index;
-	struct list_head cic_list;
-
 	/*
 	 * Fallback dummy cfqq for extreme OOM conditions
 	 */
@@ -464,37 +467,35 @@ static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
 static void cfq_dispatch_insert(struct request_queue *, struct request *);
 static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
 				       struct io_context *, gfp_t);
-static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
-						struct io_context *);
 
-static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
-					    bool is_sync)
+static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
 {
-	return cic->cfqq[is_sync];
+	/* cic->icq is the first member, %NULL will convert to %NULL */
+	return container_of(icq, struct cfq_io_cq, icq);
 }
 
-static inline void cic_set_cfqq(struct cfq_io_context *cic,
-				struct cfq_queue *cfqq, bool is_sync)
+static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd,
+					       struct io_context *ioc)
 {
-	cic->cfqq[is_sync] = cfqq;
+	if (ioc)
+		return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
+	return NULL;
 }
 
-#define CIC_DEAD_KEY	1ul
-#define CIC_DEAD_INDEX_SHIFT	1
-
-static inline void *cfqd_dead_key(struct cfq_data *cfqd)
+static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
 {
-	return (void *)(cfqd->cic_index << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY);
+	return cic->cfqq[is_sync];
 }
 
-static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic)
+static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq,
+				bool is_sync)
 {
-	struct cfq_data *cfqd = cic->key;
-
-	if (unlikely((unsigned long) cfqd & CIC_DEAD_KEY))
-		return NULL;
+	cic->cfqq[is_sync] = cfqq;
+}
 
-	return cfqd;
+static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic)
+{
+	return cic->icq.q->elevator->elevator_data;
 }
 
 /*
@@ -1561,7 +1562,7 @@ static struct request *
 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
 {
 	struct task_struct *tsk = current;
-	struct cfq_io_context *cic;
+	struct cfq_io_cq *cic;
 	struct cfq_queue *cfqq;
 
 	cic = cfq_cic_lookup(cfqd, tsk->io_context);
@@ -1687,7 +1688,7 @@ static int cfq_allow_merge(struct request_queue *q, struct request *rq,
 			   struct bio *bio)
 {
 	struct cfq_data *cfqd = q->elevator->elevator_data;
-	struct cfq_io_context *cic;
+	struct cfq_io_cq *cic;
 	struct cfq_queue *cfqq;
 
 	/*
@@ -1697,12 +1698,19 @@ static int cfq_allow_merge(struct request_queue *q, struct request *rq,
 		return false;
 
 	/*
-	 * Lookup the cfqq that this bio will be queued with. Allow
-	 * merge only if rq is queued there.
+	 * Lookup the cfqq that this bio will be queued with and allow
+	 * merge only if rq is queued there.  This function can be called
+	 * from plug merge without queue_lock.  In such cases, ioc of @rq
+	 * and %current are guaranteed to be equal.  Avoid lookup which
+	 * requires queue_lock by using @rq's cic.
 	 */
-	cic = cfq_cic_lookup(cfqd, current->io_context);
-	if (!cic)
-		return false;
+	if (current->io_context == RQ_CIC(rq)->icq.ioc) {
+		cic = RQ_CIC(rq);
+	} else {
+		cic = cfq_cic_lookup(cfqd, current->io_context);
+		if (!cic)
+			return false;
+	}
 
 	cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
 	return cfqq == RQ_CFQQ(rq);
@@ -1786,7 +1794,7 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 		cfqd->active_queue = NULL;
 
 	if (cfqd->active_cic) {
-		put_io_context(cfqd->active_cic->ioc);
+		put_io_context(cfqd->active_cic->icq.ioc, cfqd->queue);
 		cfqd->active_cic = NULL;
 	}
 }
@@ -2006,7 +2014,7 @@ static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
 {
 	struct cfq_queue *cfqq = cfqd->active_queue;
-	struct cfq_io_context *cic;
+	struct cfq_io_cq *cic;
 	unsigned long sl, group_idle = 0;
 
 	/*
@@ -2041,7 +2049,7 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
 	 * task has exited, don't wait
 	 */
 	cic = cfqd->active_cic;
-	if (!cic || !atomic_read(&cic->ioc->nr_tasks))
+	if (!cic || !atomic_read(&cic->icq.ioc->nr_tasks))
 		return;
 
 	/*
@@ -2592,9 +2600,9 @@ static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 	cfq_dispatch_insert(cfqd->queue, rq);
 
 	if (!cfqd->active_cic) {
-		struct cfq_io_context *cic = RQ_CIC(rq);
+		struct cfq_io_cq *cic = RQ_CIC(rq);
 
-		atomic_long_inc(&cic->ioc->refcount);
+		atomic_long_inc(&cic->icq.ioc->refcount);
 		cfqd->active_cic = cic;
 	}
 
@@ -2677,84 +2685,6 @@ static void cfq_put_queue(struct cfq_queue *cfqq)
 	cfq_put_cfqg(cfqg);
 }
 
-/*
- * Call func for each cic attached to this ioc.
- */
-static void
-call_for_each_cic(struct io_context *ioc,
-		  void (*func)(struct io_context *, struct cfq_io_context *))
-{
-	struct cfq_io_context *cic;
-	struct hlist_node *n;
-
-	rcu_read_lock();
-
-	hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
-		func(ioc, cic);
-
-	rcu_read_unlock();
-}
-
-static void cfq_cic_free_rcu(struct rcu_head *head)
-{
-	struct cfq_io_context *cic;
-
-	cic = container_of(head, struct cfq_io_context, rcu_head);
-
-	kmem_cache_free(cfq_ioc_pool, cic);
-	elv_ioc_count_dec(cfq_ioc_count);
-
-	if (ioc_gone) {
-		/*
-		 * CFQ scheduler is exiting, grab exit lock and check
-		 * the pending io context count. If it hits zero,
-		 * complete ioc_gone and set it back to NULL
-		 */
-		spin_lock(&ioc_gone_lock);
-		if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
-			complete(ioc_gone);
-			ioc_gone = NULL;
-		}
-		spin_unlock(&ioc_gone_lock);
-	}
-}
-
-static void cfq_cic_free(struct cfq_io_context *cic)
-{
-	call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
-}
-
-static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
-{
-	unsigned long flags;
-	unsigned long dead_key = (unsigned long) cic->key;
-
-	BUG_ON(!(dead_key & CIC_DEAD_KEY));
-
-	spin_lock_irqsave(&ioc->lock, flags);
-	radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT);
-	hlist_del_rcu(&cic->cic_list);
-	spin_unlock_irqrestore(&ioc->lock, flags);
-
-	cfq_cic_free(cic);
-}
-
-/*
- * Must be called with rcu_read_lock() held or preemption otherwise disabled.
- * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
- * and ->trim() which is called with the task lock held
- */
-static void cfq_free_io_context(struct io_context *ioc)
-{
-	/*
-	 * ioc->refcount is zero here, or we are called from elv_unregister(),
-	 * so no more cic's are allowed to be linked into this ioc.  So it
-	 * should be ok to iterate over the known list, we will see all cic's
-	 * since no new ones are added.
-	 */
-	call_for_each_cic(ioc, cic_free_func);
-}
-
 static void cfq_put_cooperator(struct cfq_queue *cfqq)
 {
 	struct cfq_queue *__cfqq, *next;
@@ -2788,27 +2718,17 @@ static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 	cfq_put_queue(cfqq);
 }
 
-static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
-					 struct cfq_io_context *cic)
+static void cfq_init_icq(struct io_cq *icq)
 {
-	struct io_context *ioc = cic->ioc;
-
-	list_del_init(&cic->queue_list);
+	struct cfq_io_cq *cic = icq_to_cic(icq);
 
-	/*
-	 * Make sure dead mark is seen for dead queues
-	 */
-	smp_wmb();
-	cic->key = cfqd_dead_key(cfqd);
+	cic->ttime.last_end_request = jiffies;
+}
 
-	rcu_read_lock();
-	if (rcu_dereference(ioc->ioc_data) == cic) {
-		rcu_read_unlock();
-		spin_lock(&ioc->lock);
-		rcu_assign_pointer(ioc->ioc_data, NULL);
-		spin_unlock(&ioc->lock);
-	} else
-		rcu_read_unlock();
+static void cfq_exit_icq(struct io_cq *icq)
+{
+	struct cfq_io_cq *cic = icq_to_cic(icq);
+	struct cfq_data *cfqd = cic_to_cfqd(cic);
 
 	if (cic->cfqq[BLK_RW_ASYNC]) {
 		cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
@@ -2821,57 +2741,6 @@ static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
 	}
 }
 
-static void cfq_exit_single_io_context(struct io_context *ioc,
-				       struct cfq_io_context *cic)
-{
-	struct cfq_data *cfqd = cic_to_cfqd(cic);
-
-	if (cfqd) {
-		struct request_queue *q = cfqd->queue;
-		unsigned long flags;
-
-		spin_lock_irqsave(q->queue_lock, flags);
-
-		/*
-		 * Ensure we get a fresh copy of the ->key to prevent
-		 * race between exiting task and queue
-		 */
-		smp_read_barrier_depends();
-		if (cic->key == cfqd)
-			__cfq_exit_single_io_context(cfqd, cic);
-
-		spin_unlock_irqrestore(q->queue_lock, flags);
-	}
-}
-
-/*
- * The process that ioc belongs to has exited, we need to clean up
- * and put the internal structures we have that belongs to that process.
- */
-static void cfq_exit_io_context(struct io_context *ioc)
-{
-	call_for_each_cic(ioc, cfq_exit_single_io_context);
-}
-
-static struct cfq_io_context *
-cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
-{
-	struct cfq_io_context *cic;
-
-	cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
-							cfqd->queue->node);
-	if (cic) {
-		cic->ttime.last_end_request = jiffies;
-		INIT_LIST_HEAD(&cic->queue_list);
-		INIT_HLIST_NODE(&cic->cic_list);
-		cic->dtor = cfq_free_io_context;
-		cic->exit = cfq_exit_io_context;
-		elv_ioc_count_inc(cfq_ioc_count);
-	}
-
-	return cic;
-}
-
 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
 {
 	struct task_struct *tsk = current;
@@ -2914,21 +2783,18 @@ static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
 	cfq_clear_cfqq_prio_changed(cfqq);
 }
 
-static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
+static void changed_ioprio(struct cfq_io_cq *cic)
 {
 	struct cfq_data *cfqd = cic_to_cfqd(cic);
 	struct cfq_queue *cfqq;
-	unsigned long flags;
 
 	if (unlikely(!cfqd))
 		return;
 
-	spin_lock_irqsave(cfqd->queue->queue_lock, flags);
-
 	cfqq = cic->cfqq[BLK_RW_ASYNC];
 	if (cfqq) {
 		struct cfq_queue *new_cfqq;
-		new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
+		new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->icq.ioc,
 						GFP_ATOMIC);
 		if (new_cfqq) {
 			cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
@@ -2939,14 +2805,6 @@ static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
 	cfqq = cic->cfqq[BLK_RW_SYNC];
 	if (cfqq)
 		cfq_mark_cfqq_prio_changed(cfqq);
-
-	spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
-}
-
-static void cfq_ioc_set_ioprio(struct io_context *ioc)
-{
-	call_for_each_cic(ioc, changed_ioprio);
-	ioc->ioprio_changed = 0;
 }
 
 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
@@ -2970,11 +2828,10 @@ static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 }
 
 #ifdef CONFIG_CFQ_GROUP_IOSCHED
-static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
+static void changed_cgroup(struct cfq_io_cq *cic)
 {
 	struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
 	struct cfq_data *cfqd = cic_to_cfqd(cic);
-	unsigned long flags;
 	struct request_queue *q;
 
 	if (unlikely(!cfqd))
@@ -2982,8 +2839,6 @@ static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
 
 	q = cfqd->queue;
 
-	spin_lock_irqsave(q->queue_lock, flags);
-
 	if (sync_cfqq) {
 		/*
 		 * Drop reference to sync queue. A new sync queue will be
@@ -2993,14 +2848,6 @@ static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
 		cic_set_cfqq(cic, NULL, 1);
 		cfq_put_queue(sync_cfqq);
 	}
-
-	spin_unlock_irqrestore(q->queue_lock, flags);
-}
-
-static void cfq_ioc_set_cgroup(struct io_context *ioc)
-{
-	call_for_each_cic(ioc, changed_cgroup);
-	ioc->cgroup_changed = 0;
 }
 #endif  /* CONFIG_CFQ_GROUP_IOSCHED */
 
@@ -3009,7 +2856,7 @@ cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
 		     struct io_context *ioc, gfp_t gfp_mask)
 {
 	struct cfq_queue *cfqq, *new_cfqq = NULL;
-	struct cfq_io_context *cic;
+	struct cfq_io_cq *cic;
 	struct cfq_group *cfqg;
 
 retry:
@@ -3100,160 +2947,6 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
 	return cfqq;
 }
 
-/*
- * We drop cfq io contexts lazily, so we may find a dead one.
- */
-static void
-cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
-		  struct cfq_io_context *cic)
-{
-	unsigned long flags;
-
-	WARN_ON(!list_empty(&cic->queue_list));
-	BUG_ON(cic->key != cfqd_dead_key(cfqd));
-
-	spin_lock_irqsave(&ioc->lock, flags);
-
-	BUG_ON(rcu_dereference_check(ioc->ioc_data,
-		lockdep_is_held(&ioc->lock)) == cic);
-
-	radix_tree_delete(&ioc->radix_root, cfqd->cic_index);
-	hlist_del_rcu(&cic->cic_list);
-	spin_unlock_irqrestore(&ioc->lock, flags);
-
-	cfq_cic_free(cic);
-}
-
-static struct cfq_io_context *
-cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
-{
-	struct cfq_io_context *cic;
-	unsigned long flags;
-
-	if (unlikely(!ioc))
-		return NULL;
-
-	rcu_read_lock();
-
-	/*
-	 * we maintain a last-hit cache, to avoid browsing over the tree
-	 */
-	cic = rcu_dereference(ioc->ioc_data);
-	if (cic && cic->key == cfqd) {
-		rcu_read_unlock();
-		return cic;
-	}
-
-	do {
-		cic = radix_tree_lookup(&ioc->radix_root, cfqd->cic_index);
-		rcu_read_unlock();
-		if (!cic)
-			break;
-		if (unlikely(cic->key != cfqd)) {
-			cfq_drop_dead_cic(cfqd, ioc, cic);
-			rcu_read_lock();
-			continue;
-		}
-
-		spin_lock_irqsave(&ioc->lock, flags);
-		rcu_assign_pointer(ioc->ioc_data, cic);
-		spin_unlock_irqrestore(&ioc->lock, flags);
-		break;
-	} while (1);
-
-	return cic;
-}
-
-/*
- * Add cic into ioc, using cfqd as the search key. This enables us to lookup
- * the process specific cfq io context when entered from the block layer.
- * Also adds the cic to a per-cfqd list, used when this queue is removed.
- */
-static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
-			struct cfq_io_context *cic, gfp_t gfp_mask)
-{
-	unsigned long flags;
-	int ret;
-
-	ret = radix_tree_preload(gfp_mask);
-	if (!ret) {
-		cic->ioc = ioc;
-		cic->key = cfqd;
-
-		spin_lock_irqsave(&ioc->lock, flags);
-		ret = radix_tree_insert(&ioc->radix_root,
-						cfqd->cic_index, cic);
-		if (!ret)
-			hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
-		spin_unlock_irqrestore(&ioc->lock, flags);
-
-		radix_tree_preload_end();
-
-		if (!ret) {
-			spin_lock_irqsave(cfqd->queue->queue_lock, flags);
-			list_add(&cic->queue_list, &cfqd->cic_list);
-			spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
-		}
-	}
-
-	if (ret && ret != -EEXIST)
-		printk(KERN_ERR "cfq: cic link failed!\n");
-
-	return ret;
-}
-
-/*
- * Setup general io context and cfq io context. There can be several cfq
- * io contexts per general io context, if this process is doing io to more
- * than one device managed by cfq.
- */
-static struct cfq_io_context *
-cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
-{
-	struct io_context *ioc = NULL;
-	struct cfq_io_context *cic;
-	int ret;
-
-	might_sleep_if(gfp_mask & __GFP_WAIT);
-
-	ioc = get_io_context(gfp_mask, cfqd->queue->node);
-	if (!ioc)
-		return NULL;
-
-retry:
-	cic = cfq_cic_lookup(cfqd, ioc);
-	if (cic)
-		goto out;
-
-	cic = cfq_alloc_io_context(cfqd, gfp_mask);
-	if (cic == NULL)
-		goto err;
-
-	ret = cfq_cic_link(cfqd, ioc, cic, gfp_mask);
-	if (ret == -EEXIST) {
-		/* someone has linked cic to ioc already */
-		cfq_cic_free(cic);
-		goto retry;
-	} else if (ret)
-		goto err_free;
-
-out:
-	smp_read_barrier_depends();
-	if (unlikely(ioc->ioprio_changed))
-		cfq_ioc_set_ioprio(ioc);
-
-#ifdef CONFIG_CFQ_GROUP_IOSCHED
-	if (unlikely(ioc->cgroup_changed))
-		cfq_ioc_set_cgroup(ioc);
-#endif
-	return cic;
-err_free:
-	cfq_cic_free(cic);
-err:
-	put_io_context(ioc);
-	return NULL;
-}
-
 static void
 __cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
 {
@@ -3267,7 +2960,7 @@ __cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
 
 static void
 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
-	struct cfq_io_context *cic)
+			struct cfq_io_cq *cic)
 {
 	if (cfq_cfqq_sync(cfqq)) {
 		__cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
@@ -3305,7 +2998,7 @@ cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
  */
 static void
 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
-		       struct cfq_io_context *cic)
+		       struct cfq_io_cq *cic)
 {
 	int old_idle, enable_idle;
 
@@ -3322,8 +3015,9 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 
 	if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
 		enable_idle = 0;
-	else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
-	    (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
+	else if (!atomic_read(&cic->icq.ioc->nr_tasks) ||
+		 !cfqd->cfq_slice_idle ||
+		 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
 		enable_idle = 0;
 	else if (sample_valid(cic->ttime.ttime_samples)) {
 		if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
@@ -3455,7 +3149,7 @@ static void
 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 		struct request *rq)
 {
-	struct cfq_io_context *cic = RQ_CIC(rq);
+	struct cfq_io_cq *cic = RQ_CIC(rq);
 
 	cfqd->rq_queued++;
 	if (rq->cmd_flags & REQ_PRIO)
@@ -3508,7 +3202,7 @@ static void cfq_insert_request(struct request_queue *q, struct request *rq)
 	struct cfq_queue *cfqq = RQ_CFQQ(rq);
 
 	cfq_log_cfqq(cfqd, cfqq, "insert_request");
-	cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
+	cfq_init_prio_data(cfqq, RQ_CIC(rq)->icq.ioc);
 
 	rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
 	list_add_tail(&rq->queuelist, &cfqq->fifo);
@@ -3558,7 +3252,7 @@ static void cfq_update_hw_tag(struct cfq_data *cfqd)
 
 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
-	struct cfq_io_context *cic = cfqd->active_cic;
+	struct cfq_io_cq *cic = cfqd->active_cic;
 
 	/* If the queue already has requests, don't wait */
 	if (!RB_EMPTY_ROOT(&cfqq->sort_list))
@@ -3695,7 +3389,7 @@ static int cfq_may_queue(struct request_queue *q, int rw)
 {
 	struct cfq_data *cfqd = q->elevator->elevator_data;
 	struct task_struct *tsk = current;
-	struct cfq_io_context *cic;
+	struct cfq_io_cq *cic;
 	struct cfq_queue *cfqq;
 
 	/*
@@ -3710,7 +3404,7 @@ static int cfq_may_queue(struct request_queue *q, int rw)
 
 	cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
 	if (cfqq) {
-		cfq_init_prio_data(cfqq, cic->ioc);
+		cfq_init_prio_data(cfqq, cic->icq.ioc);
 
 		return __cfq_may_queue(cfqq);
 	}
@@ -3731,21 +3425,17 @@ static void cfq_put_request(struct request *rq)
 		BUG_ON(!cfqq->allocated[rw]);
 		cfqq->allocated[rw]--;
 
-		put_io_context(RQ_CIC(rq)->ioc);
-
-		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);
 	}
 }
 
 static struct cfq_queue *
-cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
+cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic,
 		struct cfq_queue *cfqq)
 {
 	cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
@@ -3760,7 +3450,7 @@ cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
  * was the last process referring to said cfqq.
  */
 static struct cfq_queue *
-split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
+split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq)
 {
 	if (cfqq_process_refs(cfqq) == 1) {
 		cfqq->pid = current->pid;
@@ -3783,25 +3473,29 @@ static int
 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
 {
 	struct cfq_data *cfqd = q->elevator->elevator_data;
-	struct cfq_io_context *cic;
+	struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq);
 	const int rw = rq_data_dir(rq);
 	const bool is_sync = rq_is_sync(rq);
 	struct cfq_queue *cfqq;
-	unsigned long flags;
 
 	might_sleep_if(gfp_mask & __GFP_WAIT);
 
-	cic = cfq_get_io_context(cfqd, gfp_mask);
-
-	spin_lock_irqsave(q->queue_lock, flags);
+	spin_lock_irq(q->queue_lock);
 
-	if (!cic)
-		goto queue_fail;
+	/* handle changed notifications */
+	if (unlikely(cic->icq.changed)) {
+		if (test_and_clear_bit(ICQ_IOPRIO_CHANGED, &cic->icq.changed))
+			changed_ioprio(cic);
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+		if (test_and_clear_bit(ICQ_CGROUP_CHANGED, &cic->icq.changed))
+			changed_cgroup(cic);
+#endif
+	}
 
 new_queue:
 	cfqq = cic_to_cfqq(cic, is_sync);
 	if (!cfqq || cfqq == &cfqd->oom_cfqq) {
-		cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
+		cfqq = cfq_get_queue(cfqd, is_sync, cic->icq.ioc, gfp_mask);
 		cic_set_cfqq(cic, cfqq, is_sync);
 	} else {
 		/*
@@ -3827,17 +3521,10 @@ new_queue:
 	cfqq->allocated[rw]++;
 
 	cfqq->ref++;
-	rq->elevator_private[0] = cic;
-	rq->elevator_private[1] = cfqq;
-	rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg);
-	spin_unlock_irqrestore(q->queue_lock, flags);
+	rq->elv.priv[0] = cfqq;
+	rq->elv.priv[1] = cfq_ref_get_cfqg(cfqq->cfqg);
+	spin_unlock_irq(q->queue_lock);
 	return 0;
-
-queue_fail:
-	cfq_schedule_dispatch(cfqd);
-	spin_unlock_irqrestore(q->queue_lock, flags);
-	cfq_log(cfqd, "set_request fail");
-	return 1;
 }
 
 static void cfq_kick_queue(struct work_struct *work)
@@ -3941,14 +3628,6 @@ 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->cic_list)) {
-		struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
-							struct cfq_io_context,
-							queue_list);
-
-		__cfq_exit_single_io_context(cfqd, cic);
-	}
-
 	cfq_put_async_queues(cfqd);
 	cfq_release_cfq_groups(cfqd);
 
@@ -3963,10 +3642,6 @@ static void cfq_exit_queue(struct elevator_queue *e)
 
 	cfq_shutdown_timer_wq(cfqd);
 
-	spin_lock(&cic_index_lock);
-	ida_remove(&cic_index_ida, cfqd->cic_index);
-	spin_unlock(&cic_index_lock);
-
 	/*
 	 * Wait for cfqg->blkg->key accessors to exit their grace periods.
 	 * Do this wait only if there are other unlinked groups out
@@ -3988,24 +3663,6 @@ static void cfq_exit_queue(struct elevator_queue *e)
 	kfree(cfqd);
 }
 
-static int cfq_alloc_cic_index(void)
-{
-	int index, error;
-
-	do {
-		if (!ida_pre_get(&cic_index_ida, GFP_KERNEL))
-			return -ENOMEM;
-
-		spin_lock(&cic_index_lock);
-		error = ida_get_new(&cic_index_ida, &index);
-		spin_unlock(&cic_index_lock);
-		if (error && error != -EAGAIN)
-			return error;
-	} while (error);
-
-	return index;
-}
-
 static void *cfq_init_queue(struct request_queue *q)
 {
 	struct cfq_data *cfqd;
@@ -4013,23 +3670,9 @@ static void *cfq_init_queue(struct request_queue *q)
 	struct cfq_group *cfqg;
 	struct cfq_rb_root *st;
 
-	i = cfq_alloc_cic_index();
-	if (i < 0)
-		return NULL;
-
 	cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
-	if (!cfqd) {
-		spin_lock(&cic_index_lock);
-		ida_remove(&cic_index_ida, i);
-		spin_unlock(&cic_index_lock);
+	if (!cfqd)
 		return NULL;
-	}
-
-	/*
-	 * Don't need take queue_lock in the routine, since we are
-	 * initializing the ioscheduler, and nobody is using cfqd
-	 */
-	cfqd->cic_index = i;
 
 	/* Init root service tree */
 	cfqd->grp_service_tree = CFQ_RB_ROOT;
@@ -4055,11 +3698,6 @@ static void *cfq_init_queue(struct request_queue *q)
 
 	if (blkio_alloc_blkg_stats(&cfqg->blkg)) {
 		kfree(cfqg);
-
-		spin_lock(&cic_index_lock);
-		ida_remove(&cic_index_ida, cfqd->cic_index);
-		spin_unlock(&cic_index_lock);
-
 		kfree(cfqd);
 		return NULL;
 	}
@@ -4091,8 +3729,6 @@ 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->cic_list);
-
 	cfqd->queue = q;
 
 	init_timer(&cfqd->idle_slice_timer);
@@ -4121,34 +3757,6 @@ static void *cfq_init_queue(struct request_queue *q)
 	return cfqd;
 }
 
-static void cfq_slab_kill(void)
-{
-	/*
-	 * Caller already ensured that pending RCU callbacks are completed,
-	 * so we should have no busy allocations at this point.
-	 */
-	if (cfq_pool)
-		kmem_cache_destroy(cfq_pool);
-	if (cfq_ioc_pool)
-		kmem_cache_destroy(cfq_ioc_pool);
-}
-
-static int __init cfq_slab_setup(void)
-{
-	cfq_pool = KMEM_CACHE(cfq_queue, 0);
-	if (!cfq_pool)
-		goto fail;
-
-	cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
-	if (!cfq_ioc_pool)
-		goto fail;
-
-	return 0;
-fail:
-	cfq_slab_kill();
-	return -ENOMEM;
-}
-
 /*
  * sysfs parts below -->
  */
@@ -4254,15 +3862,18 @@ static struct elevator_type iosched_cfq = {
 		.elevator_completed_req_fn =	cfq_completed_request,
 		.elevator_former_req_fn =	elv_rb_former_request,
 		.elevator_latter_req_fn =	elv_rb_latter_request,
+		.elevator_init_icq_fn =		cfq_init_icq,
+		.elevator_exit_icq_fn =		cfq_exit_icq,
 		.elevator_set_req_fn =		cfq_set_request,
 		.elevator_put_req_fn =		cfq_put_request,
 		.elevator_may_queue_fn =	cfq_may_queue,
 		.elevator_init_fn =		cfq_init_queue,
 		.elevator_exit_fn =		cfq_exit_queue,
-		.trim =				cfq_free_io_context,
 	},
+	.icq_size	=	sizeof(struct cfq_io_cq),
+	.icq_align	=	__alignof__(struct cfq_io_cq),
 	.elevator_attrs =	cfq_attrs,
-	.elevator_name =	"cfq",
+	.elevator_name	=	"cfq",
 	.elevator_owner =	THIS_MODULE,
 };
 
@@ -4280,6 +3891,8 @@ static struct blkio_policy_type blkio_policy_cfq;
 
 static int __init cfq_init(void)
 {
+	int ret;
+
 	/*
 	 * could be 0 on HZ < 1000 setups
 	 */
@@ -4294,10 +3907,16 @@ static int __init cfq_init(void)
 #else
 		cfq_group_idle = 0;
 #endif
-	if (cfq_slab_setup())
+	cfq_pool = KMEM_CACHE(cfq_queue, 0);
+	if (!cfq_pool)
 		return -ENOMEM;
 
-	elv_register(&iosched_cfq);
+	ret = elv_register(&iosched_cfq);
+	if (ret) {
+		kmem_cache_destroy(cfq_pool);
+		return ret;
+	}
+
 	blkio_policy_register(&blkio_policy_cfq);
 
 	return 0;
@@ -4305,21 +3924,9 @@ static int __init cfq_init(void)
 
 static void __exit cfq_exit(void)
 {
-	DECLARE_COMPLETION_ONSTACK(all_gone);
 	blkio_policy_unregister(&blkio_policy_cfq);
 	elv_unregister(&iosched_cfq);
-	ioc_gone = &all_gone;
-	/* ioc_gone's update must be visible before reading ioc_count */
-	smp_wmb();
-
-	/*
-	 * this also protects us from entering cfq_slab_kill() with
-	 * pending RCU callbacks
-	 */
-	if (elv_ioc_count_read(cfq_ioc_count))
-		wait_for_completion(&all_gone);
-	ida_destroy(&cic_index_ida);
-	cfq_slab_kill();
+	kmem_cache_destroy(cfq_pool);
 }
 
 module_init(cfq_init);
diff --git a/block/compat_ioctl.c b/block/compat_ioctl.c
index 7b72502..7c668c8 100644
--- a/block/compat_ioctl.c
+++ b/block/compat_ioctl.c
@@ -719,6 +719,9 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 	case BLKSECTGET:
 		return compat_put_ushort(arg,
 					 queue_max_sectors(bdev_get_queue(bdev)));
+	case BLKROTATIONAL:
+		return compat_put_ushort(arg,
+					 !blk_queue_nonrot(bdev_get_queue(bdev)));
 	case BLKRASET: /* compatible, but no compat_ptr (!) */
 	case BLKFRASET:
 		if (!capable(CAP_SYS_ADMIN))
diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
index c644137..7bf12d7 100644
--- a/block/deadline-iosched.c
+++ b/block/deadline-iosched.c
@@ -448,9 +448,7 @@ static struct elevator_type iosched_deadline = {
 
 static int __init deadline_init(void)
 {
-	elv_register(&iosched_deadline);
-
-	return 0;
+	return elv_register(&iosched_deadline);
 }
 
 static void __exit deadline_exit(void)
diff --git a/block/elevator.c b/block/elevator.c
index 66343d6..91e18f8 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;
 }
@@ -168,17 +168,13 @@ static struct elevator_type *elevator_get(const char *name)
 	return e;
 }
 
-static void *elevator_init_queue(struct request_queue *q,
-				 struct elevator_queue *eq)
+static int 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)
-{
-	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 +203,7 @@ 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 +227,7 @@ 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 +236,7 @@ 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 +273,13 @@ 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 +287,8 @@ 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);
@@ -504,8 +498,8 @@ 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 +542,8 @@ 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 +557,8 @@ 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 +575,8 @@ 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 +602,12 @@ 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 +696,7 @@ 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 +725,8 @@ 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 +734,8 @@ 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 +743,8 @@ 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 +752,16 @@ 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 +796,8 @@ 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 +815,7 @@ 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 +833,7 @@ 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 +848,13 @@ 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 +867,55 @@ 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 +923,26 @@ 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 +955,41 @@ 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 +999,6 @@ 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 +1023,7 @@ 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 +1058,7 @@ 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) {
diff --git a/block/genhd.c b/block/genhd.c
index 83e7c04..23b4f70 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -614,7 +614,7 @@ void add_disk(struct gendisk *disk)
 	 * Take an extra ref on queue which will be put on disk_release()
 	 * so that it sticks around as long as @disk is there.
 	 */
-	WARN_ON_ONCE(blk_get_queue(disk->queue));
+	WARN_ON_ONCE(!blk_get_queue(disk->queue));
 
 	retval = sysfs_create_link(&disk_to_dev(disk)->kobj, &bdi->dev->kobj,
 				   "bdi");
diff --git a/block/ioctl.c b/block/ioctl.c
index 4828fa3..ba15b2d 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -296,6 +296,8 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
 		return put_uint(arg, bdev_discard_zeroes_data(bdev));
 	case BLKSECTGET:
 		return put_ushort(arg, queue_max_sectors(bdev_get_queue(bdev)));
+	case BLKROTATIONAL:
+		return put_ushort(arg, !blk_queue_nonrot(bdev_get_queue(bdev)));
 	case BLKRASET:
 	case BLKFRASET:
 		if(!capable(CAP_SYS_ADMIN))
diff --git a/block/noop-iosched.c b/block/noop-iosched.c
index 06389e9..413a0b1 100644
--- a/block/noop-iosched.c
+++ b/block/noop-iosched.c
@@ -94,9 +94,7 @@ static struct elevator_type elevator_noop = {
 
 static int __init noop_init(void)
 {
-	elv_register(&elevator_noop);
-
-	return 0;
+	return elv_register(&elevator_noop);
 }
 
 static void __exit noop_exit(void)