Merge ../linux-2.6

6 files changed, 178 insertions, 89 deletions

diff --git a/block/as-iosched.c b/block/as-iosched.c
index 296708ceceb2..a7caf35ca0c2 100644
--- a/block/as-iosched.c
+++ b/block/as-iosched.c
@@ -1648,17 +1648,17 @@ static void as_exit_queue(elevator_t *e)
  * initialize elevator private data (as_data), and alloc a arq for
  * each request on the free lists
  */
-static int as_init_queue(request_queue_t *q, elevator_t *e)
+static void *as_init_queue(request_queue_t *q, elevator_t *e)
 {
         struct as_data *ad;
         int i;
 
         if (!arq_pool)
-                return -ENOMEM;
+                return NULL;
 
         ad = kmalloc_node(sizeof(*ad), GFP_KERNEL, q->node);
         if (!ad)
-                return -ENOMEM;
+                return NULL;
         memset(ad, 0, sizeof(*ad));
 
         ad->q = q; /* Identify what queue the data belongs to */
@@ -1667,7 +1667,7 @@ static int as_init_queue(request_queue_t *q, elevator_t *e)
                                 GFP_KERNEL, q->node);
         if (!ad->hash) {
                 kfree(ad);
-                return -ENOMEM;
+                return NULL;
         }
 
         ad->arq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
@@ -1675,7 +1675,7 @@ static int as_init_queue(request_queue_t *q, elevator_t *e)
         if (!ad->arq_pool) {
                 kfree(ad->hash);
                 kfree(ad);
-                return -ENOMEM;
+                return NULL;
         }
 
         /* anticipatory scheduling helpers */
@@ -1696,14 +1696,13 @@ static int as_init_queue(request_queue_t *q, elevator_t *e)
         ad->antic_expire = default_antic_expire;
         ad->batch_expire[REQ_SYNC] = default_read_batch_expire;
         ad->batch_expire[REQ_ASYNC] = default_write_batch_expire;
-        e->elevator_data = ad;
 
         ad->current_batch_expires = jiffies + ad->batch_expire[REQ_SYNC];
         ad->write_batch_count = ad->batch_expire[REQ_ASYNC] / 10;
         if (ad->write_batch_count < 2)
                 ad->write_batch_count = 2;
 
-        return 0;
+        return ad;
 }
 
 /*
@@ -1844,9 +1843,10 @@ static void __exit as_exit(void)
         DECLARE_COMPLETION(all_gone);
         elv_unregister(&iosched_as);
         ioc_gone = &all_gone;
-        barrier();
+        /* ioc_gone's update must be visible before reading ioc_count */
+        smp_wmb();
         if (atomic_read(&ioc_count))
-                complete(ioc_gone);
+                wait_for_completion(ioc_gone);
         synchronize_rcu();
         kmem_cache_destroy(arq_pool);
 }
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 67d446de0227..a46d030e092a 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -33,7 +33,7 @@ static int cfq_slice_idle = HZ / 70;
 
 #define CFQ_KEY_ASYNC           (0)
 
-static DEFINE_RWLOCK(cfq_exit_lock);
+static DEFINE_SPINLOCK(cfq_exit_lock);
 
 /*
  * for the hash of cfqq inside the cfqd
@@ -133,6 +133,7 @@ struct cfq_data {
         mempool_t *crq_pool;
 
         int rq_in_driver;
+        int hw_tag;
 
         /*
          * schedule slice state info
@@ -500,10 +501,13 @@ static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted)
 
         /*
          * if queue was preempted, just add to front to be fair. busy_rr
-         * isn't sorted.
+         * isn't sorted, but insert at the back for fairness.
          */
         if (preempted || list == &cfqd->busy_rr) {
-                list_add(&cfqq->cfq_list, list);
+                if (preempted)
+                        list = list->prev;
+
+                list_add_tail(&cfqq->cfq_list, list);
                 return;
         }
 
@@ -664,6 +668,15 @@ static void cfq_activate_request(request_queue_t *q, struct request *rq)
         struct cfq_data *cfqd = q->elevator->elevator_data;
 
         cfqd->rq_in_driver++;
+
+        /*
+         * If the depth is larger 1, it really could be queueing. But lets
+         * make the mark a little higher - idling could still be good for
+         * low queueing, and a low queueing number could also just indicate
+         * a SCSI mid layer like behaviour where limit+1 is often seen.
+         */
+        if (!cfqd->hw_tag && cfqd->rq_in_driver > 4)
+                cfqd->hw_tag = 1;
 }
 
 static void cfq_deactivate_request(request_queue_t *q, struct request *rq)
@@ -879,6 +892,13 @@ static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd)
                 cfqq = list_entry_cfqq(cfqd->cur_rr.next);
 
         /*
+         * If no new queues are available, check if the busy list has some
+         * before falling back to idle io.
+         */
+        if (!cfqq && !list_empty(&cfqd->busy_rr))
+                cfqq = list_entry_cfqq(cfqd->busy_rr.next);
+
+        /*
          * if we have idle queues and no rt or be queues had pending
          * requests, either allow immediate service if the grace period
          * has passed or arm the idle grace timer
@@ -1284,7 +1304,7 @@ static void cfq_exit_io_context(struct io_context *ioc)
         /*
          * put the reference this task is holding to the various queues
          */
-        read_lock_irqsave(&cfq_exit_lock, flags);
+        spin_lock_irqsave(&cfq_exit_lock, flags);
 
         n = rb_first(&ioc->cic_root);
         while (n != NULL) {
@@ -1294,7 +1314,7 @@ static void cfq_exit_io_context(struct io_context *ioc)
                 n = rb_next(n);
         }
 
-        read_unlock_irqrestore(&cfq_exit_lock, flags);
+        spin_unlock_irqrestore(&cfq_exit_lock, flags);
 }
 
 static struct cfq_io_context *
@@ -1400,17 +1420,17 @@ static int cfq_ioc_set_ioprio(struct io_context *ioc, unsigned int ioprio)
         struct cfq_io_context *cic;
         struct rb_node *n;
 
-        write_lock(&cfq_exit_lock);
+        spin_lock(&cfq_exit_lock);
 
         n = rb_first(&ioc->cic_root);
         while (n != NULL) {
                 cic = rb_entry(n, struct cfq_io_context, rb_node);
- 
+
                 changed_ioprio(cic);
                 n = rb_next(n);
         }
 
-        write_unlock(&cfq_exit_lock);
+        spin_unlock(&cfq_exit_lock);
 
         return 0;
 }
@@ -1458,7 +1478,8 @@ retry:
                  * set ->slice_left to allow preemption for a new process
                  */
                 cfqq->slice_left = 2 * cfqd->cfq_slice_idle;
-                cfq_mark_cfqq_idle_window(cfqq);
+                if (!cfqd->hw_tag)
+                        cfq_mark_cfqq_idle_window(cfqq);
                 cfq_mark_cfqq_prio_changed(cfqq);
                 cfq_init_prio_data(cfqq);
         }
@@ -1472,19 +1493,38 @@ out:
         return cfqq;
 }
 
+static void
+cfq_drop_dead_cic(struct io_context *ioc, struct cfq_io_context *cic)
+{
+        spin_lock(&cfq_exit_lock);
+        rb_erase(&cic->rb_node, &ioc->cic_root);
+        list_del_init(&cic->queue_list);
+        spin_unlock(&cfq_exit_lock);
+        kmem_cache_free(cfq_ioc_pool, cic);
+        atomic_dec(&ioc_count);
+}
+
 static struct cfq_io_context *
 cfq_cic_rb_lookup(struct cfq_data *cfqd, struct io_context *ioc)
 {
-        struct rb_node *n = ioc->cic_root.rb_node;
+        struct rb_node *n;
         struct cfq_io_context *cic;
-        void *key = cfqd;
+        void *k, *key = cfqd;
 
+restart:
+        n = ioc->cic_root.rb_node;
         while (n) {
                 cic = rb_entry(n, struct cfq_io_context, rb_node);
+                /* ->key must be copied to avoid race with cfq_exit_queue() */
+                k = cic->key;
+                if (unlikely(!k)) {
+                        cfq_drop_dead_cic(ioc, cic);
+                        goto restart;
+                }
 
-                if (key < cic->key)
+                if (key < k)
                         n = n->rb_left;
-                else if (key > cic->key)
+                else if (key > k)
                         n = n->rb_right;
                 else
                         return cic;
@@ -1497,33 +1537,41 @@ static inline void
 cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
              struct cfq_io_context *cic)
 {
-        struct rb_node **p = &ioc->cic_root.rb_node;
-        struct rb_node *parent = NULL;
+        struct rb_node **p;
+        struct rb_node *parent;
         struct cfq_io_context *__cic;
-
-        read_lock(&cfq_exit_lock);
+        void *k;
 
         cic->ioc = ioc;
         cic->key = cfqd;
 
         ioc->set_ioprio = cfq_ioc_set_ioprio;
-
+restart:
+        parent = NULL;
+        p = &ioc->cic_root.rb_node;
         while (*p) {
                 parent = *p;
                 __cic = rb_entry(parent, struct cfq_io_context, rb_node);
+                /* ->key must be copied to avoid race with cfq_exit_queue() */
+                k = __cic->key;
+                if (unlikely(!k)) {
+                        cfq_drop_dead_cic(ioc, cic);
+                        goto restart;
+                }
 
-                if (cic->key < __cic->key)
+                if (cic->key < k)
                         p = &(*p)->rb_left;
-                else if (cic->key > __cic->key)
+                else if (cic->key > k)
                         p = &(*p)->rb_right;
                 else
                         BUG();
         }
 
+        spin_lock(&cfq_exit_lock);
         rb_link_node(&cic->rb_node, parent, p);
         rb_insert_color(&cic->rb_node, &ioc->cic_root);
         list_add(&cic->queue_list, &cfqd->cic_list);
-        read_unlock(&cfq_exit_lock);
+        spin_unlock(&cfq_exit_lock);
 }
 
 /*
@@ -1622,7 +1670,7 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 {
         int enable_idle = cfq_cfqq_idle_window(cfqq);
 
-        if (!cic->ioc->task || !cfqd->cfq_slice_idle)
+        if (!cic->ioc->task || !cfqd->cfq_slice_idle || cfqd->hw_tag)
                 enable_idle = 0;
         else if (sample_valid(cic->ttime_samples)) {
                 if (cic->ttime_mean > cfqd->cfq_slice_idle)
@@ -1713,14 +1761,24 @@ cfq_crq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 
         cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq);
 
+        cic = crq->io_context;
+
         /*
          * we never wait for an async request and we don't allow preemption
          * of an async request. so just return early
          */
-        if (!cfq_crq_is_sync(crq))
+        if (!cfq_crq_is_sync(crq)) {
+                /*
+                 * sync process issued an async request, if it's waiting
+                 * then expire it and kick rq handling.
+                 */
+                if (cic == cfqd->active_cic &&
+                    del_timer(&cfqd->idle_slice_timer)) {
+                        cfq_slice_expired(cfqd, 0);
+                        cfq_start_queueing(cfqd, cfqq);
+                }
                 return;
-
-        cic = crq->io_context;
+        }
 
         cfq_update_io_thinktime(cfqd, cic);
         cfq_update_io_seektime(cfqd, cic, crq);
@@ -2138,10 +2196,9 @@ static void cfq_idle_class_timer(unsigned long data)
          * race with a non-idle queue, reset timer
          */
         end = cfqd->last_end_request + CFQ_IDLE_GRACE;
-        if (!time_after_eq(jiffies, end)) {
-                cfqd->idle_class_timer.expires = end;
-                add_timer(&cfqd->idle_class_timer);
-        } else
+        if (!time_after_eq(jiffies, end))
+                mod_timer(&cfqd->idle_class_timer, end);
+        else
                 cfq_schedule_dispatch(cfqd);
 
         spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
@@ -2161,7 +2218,7 @@ static void cfq_exit_queue(elevator_t *e)
 
         cfq_shutdown_timer_wq(cfqd);
 
-        write_lock(&cfq_exit_lock);
+        spin_lock(&cfq_exit_lock);
         spin_lock_irq(q->queue_lock);
 
         if (cfqd->active_queue)
@@ -2184,7 +2241,7 @@ static void cfq_exit_queue(elevator_t *e)
         }
 
         spin_unlock_irq(q->queue_lock);
-        write_unlock(&cfq_exit_lock);
+        spin_unlock(&cfq_exit_lock);
 
         cfq_shutdown_timer_wq(cfqd);
 
@@ -2194,14 +2251,14 @@ static void cfq_exit_queue(elevator_t *e)
         kfree(cfqd);
 }
 
-static int cfq_init_queue(request_queue_t *q, elevator_t *e)
+static void *cfq_init_queue(request_queue_t *q, elevator_t *e)
 {
         struct cfq_data *cfqd;
         int i;
 
         cfqd = kmalloc(sizeof(*cfqd), GFP_KERNEL);
         if (!cfqd)
-                return -ENOMEM;
+                return NULL;
 
         memset(cfqd, 0, sizeof(*cfqd));
 
@@ -2231,8 +2288,6 @@ static int cfq_init_queue(request_queue_t *q, elevator_t *e)
         for (i = 0; i < CFQ_QHASH_ENTRIES; i++)
                 INIT_HLIST_HEAD(&cfqd->cfq_hash[i]);
 
-        e->elevator_data = cfqd;
-
         cfqd->queue = q;
 
         cfqd->max_queued = q->nr_requests / 4;
@@ -2259,14 +2314,14 @@ static int cfq_init_queue(request_queue_t *q, elevator_t *e)
         cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
         cfqd->cfq_slice_idle = cfq_slice_idle;
 
-        return 0;
+        return cfqd;
 out_crqpool:
         kfree(cfqd->cfq_hash);
 out_cfqhash:
         kfree(cfqd->crq_hash);
 out_crqhash:
         kfree(cfqd);
-        return -ENOMEM;
+        return NULL;
 }
 
 static void cfq_slab_kill(void)
@@ -2439,9 +2494,10 @@ static void __exit cfq_exit(void)
         DECLARE_COMPLETION(all_gone);
         elv_unregister(&iosched_cfq);
         ioc_gone = &all_gone;
-        barrier();
+        /* ioc_gone's update must be visible before reading ioc_count */
+        smp_wmb();
         if (atomic_read(&ioc_count))
-                complete(ioc_gone);
+                wait_for_completion(ioc_gone);
         synchronize_rcu();
         cfq_slab_kill();
 }
diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
index 399fa1e60e1f..3bd0415a9828 100644
--- a/block/deadline-iosched.c
+++ b/block/deadline-iosched.c
@@ -613,24 +613,24 @@ static void deadline_exit_queue(elevator_t *e)
  * initialize elevator private data (deadline_data), and alloc a drq for
  * each request on the free lists
  */
-static int deadline_init_queue(request_queue_t *q, elevator_t *e)
+static void *deadline_init_queue(request_queue_t *q, elevator_t *e)
 {
         struct deadline_data *dd;
         int i;
 
         if (!drq_pool)
-                return -ENOMEM;
+                return NULL;
 
         dd = kmalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
         if (!dd)
-                return -ENOMEM;
+                return NULL;
         memset(dd, 0, sizeof(*dd));
 
         dd->hash = kmalloc_node(sizeof(struct list_head)*DL_HASH_ENTRIES,
                                 GFP_KERNEL, q->node);
         if (!dd->hash) {
                 kfree(dd);
-                return -ENOMEM;
+                return NULL;
         }
 
         dd->drq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
@@ -638,7 +638,7 @@ static int deadline_init_queue(request_queue_t *q, elevator_t *e)
         if (!dd->drq_pool) {
                 kfree(dd->hash);
                 kfree(dd);
-                return -ENOMEM;
+                return NULL;
         }
 
         for (i = 0; i < DL_HASH_ENTRIES; i++)
@@ -653,8 +653,7 @@ static int deadline_init_queue(request_queue_t *q, elevator_t *e)
         dd->writes_starved = writes_starved;
         dd->front_merges = 1;
         dd->fifo_batch = fifo_batch;
-        e->elevator_data = dd;
-        return 0;
+        return dd;
 }
 
 static void deadline_put_request(request_queue_t *q, struct request *rq)
diff --git a/block/elevator.c b/block/elevator.c
index 0d6be03d929e..a0afdd317cef 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -121,16 +121,16 @@ static struct elevator_type *elevator_get(const char *name)
         return e;
 }
 
-static int elevator_attach(request_queue_t *q, struct elevator_queue *eq)
+static void *elevator_init_queue(request_queue_t *q, struct elevator_queue *eq)
 {
-        int ret = 0;
+        return eq->ops->elevator_init_fn(q, eq);
+}
 
+static void elevator_attach(request_queue_t *q, struct elevator_queue *eq,
+                           void *data)
+{
         q->elevator = eq;
-
-        if (eq->ops->elevator_init_fn)
-                ret = eq->ops->elevator_init_fn(q, eq);
-
-        return ret;
+        eq->elevator_data = data;
 }
 
 static char chosen_elevator[16];
@@ -181,6 +181,7 @@ int elevator_init(request_queue_t *q, char *name)
         struct elevator_type *e = NULL;
         struct elevator_queue *eq;
         int ret = 0;
+        void *data;
 
         INIT_LIST_HEAD(&q->queue_head);
         q->last_merge = NULL;
@@ -202,10 +203,13 @@ int elevator_init(request_queue_t *q, char *name)
         if (!eq)
                 return -ENOMEM;
 
-        ret = elevator_attach(q, eq);
-        if (ret)
+        data = elevator_init_queue(q, eq);
+        if (!data) {
                 kobject_put(&eq->kobj);
+                return -ENOMEM;
+        }
 
+        elevator_attach(q, eq, data);
         return ret;
 }
 
@@ -333,6 +337,7 @@ void elv_insert(request_queue_t *q, struct request *rq, int where)
 {
         struct list_head *pos;
         unsigned ordseq;
+        int unplug_it = 1;
 
         blk_add_trace_rq(q, rq, BLK_TA_INSERT);
 
@@ -399,6 +404,11 @@ void elv_insert(request_queue_t *q, struct request *rq, int where)
                 }
 
                 list_add_tail(&rq->queuelist, pos);
+                /*
+                 * most requeues happen because of a busy condition, don't
+                 * force unplug of the queue for that case.
+                 */
+                unplug_it = 0;
                 break;
 
         default:
@@ -407,7 +417,7 @@ void elv_insert(request_queue_t *q, struct request *rq, int where)
                 BUG();
         }
 
-        if (blk_queue_plugged(q)) {
+        if (unplug_it && blk_queue_plugged(q)) {
                 int nrq = q->rq.count[READ] + q->rq.count[WRITE]
                         - q->in_flight;
 
@@ -716,13 +726,16 @@ int elv_register_queue(struct request_queue *q)
         return error;
 }
 
+static void __elv_unregister_queue(elevator_t *e)
+{
+        kobject_uevent(&e->kobj, KOBJ_REMOVE);
+        kobject_del(&e->kobj);
+}
+
 void elv_unregister_queue(struct request_queue *q)
 {
-        if (q) {
-                elevator_t *e = q->elevator;
-                kobject_uevent(&e->kobj, KOBJ_REMOVE);
-                kobject_del(&e->kobj);
-        }
+        if (q)
+                __elv_unregister_queue(q->elevator);
 }
 
 int elv_register(struct elevator_type *e)
@@ -774,6 +787,7 @@ EXPORT_SYMBOL_GPL(elv_unregister);
 static int elevator_switch(request_queue_t *q, struct elevator_type *new_e)
 {
         elevator_t *old_elevator, *e;
+        void *data;
 
         /*
          * Allocate new elevator
@@ -782,6 +796,12 @@ static int elevator_switch(request_queue_t *q, struct elevator_type *new_e)
         if (!e)
                 return 0;
 
+        data = elevator_init_queue(q, e);
+        if (!data) {
+                kobject_put(&e->kobj);
+                return 0;
+        }
+
         /*
          * Turn on BYPASS and drain all requests w/ elevator private data
          */
@@ -800,19 +820,19 @@ static int elevator_switch(request_queue_t *q, struct elevator_type *new_e)
                 elv_drain_elevator(q);
         }
 
-        spin_unlock_irq(q->queue_lock);
-
         /*
-         * unregister old elevator data
+         * Remember old elevator.
          */
-        elv_unregister_queue(q);
         old_elevator = q->elevator;
 
         /*
          * attach and start new elevator
          */
-        if (elevator_attach(q, e))
-                goto fail;
+        elevator_attach(q, e, data);
+
+        spin_unlock_irq(q->queue_lock);
+
+        __elv_unregister_queue(old_elevator);
 
         if (elv_register_queue(q))
                 goto fail_register;
@@ -831,7 +851,6 @@ fail_register:
          */
         elevator_exit(e);
         e = NULL;
-fail:
         q->elevator = old_elevator;
         elv_register_queue(q);
         clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
@@ -895,10 +914,8 @@ ssize_t elv_iosched_show(request_queue_t *q, char *name)
 EXPORT_SYMBOL(elv_dispatch_sort);
 EXPORT_SYMBOL(elv_add_request);
 EXPORT_SYMBOL(__elv_add_request);
-EXPORT_SYMBOL(elv_requeue_request);
 EXPORT_SYMBOL(elv_next_request);
 EXPORT_SYMBOL(elv_dequeue_request);
 EXPORT_SYMBOL(elv_queue_empty);
-EXPORT_SYMBOL(elv_completed_request);
 EXPORT_SYMBOL(elevator_exit);
 EXPORT_SYMBOL(elevator_init);
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index e112d1a5dab6..7eb36c53f4b7 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -1554,7 +1554,7 @@ void blk_plug_device(request_queue_t *q)
          * don't plug a stopped queue, it must be paired with blk_start_queue()
          * which will restart the queueing
          */
-        if (test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags))
+        if (blk_queue_stopped(q))
                 return;
 
         if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) {
@@ -1587,7 +1587,7 @@ EXPORT_SYMBOL(blk_remove_plug);
  */
 void __generic_unplug_device(request_queue_t *q)
 {
-        if (unlikely(test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags)))
+        if (unlikely(blk_queue_stopped(q)))
                 return;
 
         if (!blk_remove_plug(q))
@@ -1732,8 +1732,21 @@ void blk_run_queue(struct request_queue *q)
 
         spin_lock_irqsave(q->queue_lock, flags);
         blk_remove_plug(q);
-        if (!elv_queue_empty(q))
-                q->request_fn(q);
+
+        /*
+         * Only recurse once to avoid overrunning the stack, let the unplug
+         * handling reinvoke the handler shortly if we already got there.
+         */
+        if (!elv_queue_empty(q)) {
+                if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
+                        q->request_fn(q);
+                        clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags);
+                } else {
+                        blk_plug_device(q);
+                        kblockd_schedule_work(&q->unplug_work);
+                }
+        }
+
         spin_unlock_irqrestore(q->queue_lock, flags);
 }
 EXPORT_SYMBOL(blk_run_queue);
@@ -3385,7 +3398,7 @@ static int blk_cpu_notify(struct notifier_block *self, unsigned long action,
 }
 
 
-static struct notifier_block __devinitdata blk_cpu_notifier = {
+static struct notifier_block blk_cpu_notifier = {
         .notifier_call  = blk_cpu_notify,
 };
 
@@ -3439,7 +3452,12 @@ void end_that_request_last(struct request *req, int uptodate)
         if (unlikely(laptop_mode) && blk_fs_request(req))
                 laptop_io_completion();
 
-        if (disk && blk_fs_request(req)) {
+        /*
+         * Account IO completion.  bar_rq isn't accounted as a normal
+         * IO on queueing nor completion.  Accounting the containing
+         * request is enough.
+         */
+        if (disk && blk_fs_request(req) && req != &req->q->bar_rq) {
                 unsigned long duration = jiffies - req->start_time;
                 const int rw = rq_data_dir(req);
 
diff --git a/block/noop-iosched.c b/block/noop-iosched.c
index f370e4a7fe6d..56a7c620574f 100644
--- a/block/noop-iosched.c
+++ b/block/noop-iosched.c
@@ -65,16 +65,15 @@ noop_latter_request(request_queue_t *q, struct request *rq)
         return list_entry(rq->queuelist.next, struct request, queuelist);
 }
 
-static int noop_init_queue(request_queue_t *q, elevator_t *e)
+static void *noop_init_queue(request_queue_t *q, elevator_t *e)
 {
         struct noop_data *nd;
 
         nd = kmalloc(sizeof(*nd), GFP_KERNEL);
         if (!nd)
-                return -ENOMEM;
+                return NULL;
         INIT_LIST_HEAD(&nd->queue);
-        e->elevator_data = nd;
-        return 0;
+        return nd;
 }
 
 static void noop_exit_queue(elevator_t *e)