18 files changed, 186 insertions, 187 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 78b7b0cb7216..5fa3dd2705c6 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -204,7 +204,7 @@ static void blk_delay_work(struct work_struct *work)
 
         q = container_of(work, struct request_queue, delay_work.work);
         spin_lock_irq(q->queue_lock);
-        __blk_run_queue(q, false);
+        __blk_run_queue(q);
         spin_unlock_irq(q->queue_lock);
 }
 
@@ -220,7 +220,8 @@ static void blk_delay_work(struct work_struct *work)
  */
 void blk_delay_queue(struct request_queue *q, unsigned long msecs)
 {
-        schedule_delayed_work(&q->delay_work, msecs_to_jiffies(msecs));
+        queue_delayed_work(kblockd_workqueue, &q->delay_work,
+                                msecs_to_jiffies(msecs));
 }
 EXPORT_SYMBOL(blk_delay_queue);
 
@@ -238,7 +239,7 @@ void blk_start_queue(struct request_queue *q)
         WARN_ON(!irqs_disabled());
 
         queue_flag_clear(QUEUE_FLAG_STOPPED, q);
-        __blk_run_queue(q, false);
+        __blk_run_queue(q);
 }
 EXPORT_SYMBOL(blk_start_queue);
 
@@ -296,9 +297,8 @@ EXPORT_SYMBOL(blk_sync_queue);
  * Description:
  *    See @blk_run_queue. This variant must be called with the queue lock
  *    held and interrupts disabled.
- *
  */
-void __blk_run_queue(struct request_queue *q, bool force_kblockd)
+void __blk_run_queue(struct request_queue *q)
 {
         if (unlikely(blk_queue_stopped(q)))
                 return;
@@ -307,7 +307,7 @@ void __blk_run_queue(struct request_queue *q, bool force_kblockd)
          * Only recurse once to avoid overrunning the stack, let the unplug
          * handling reinvoke the handler shortly if we already got there.
          */
-        if (!force_kblockd && !queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) {
+        if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) {
                 q->request_fn(q);
                 queue_flag_clear(QUEUE_FLAG_REENTER, q);
         } else
@@ -316,6 +316,20 @@ void __blk_run_queue(struct request_queue *q, bool force_kblockd)
 EXPORT_SYMBOL(__blk_run_queue);
 
 /**
+ * blk_run_queue_async - run a single device queue in workqueue context
+ * @q:  The queue to run
+ *
+ * Description:
+ *    Tells kblockd to perform the equivalent of @blk_run_queue on behalf
+ *    of us.
+ */
+void blk_run_queue_async(struct request_queue *q)
+{
+        if (likely(!blk_queue_stopped(q)))
+                queue_delayed_work(kblockd_workqueue, &q->delay_work, 0);
+}
+
+/**
  * blk_run_queue - run a single device queue
  * @q: The queue to run
  *
@@ -328,7 +342,7 @@ void blk_run_queue(struct request_queue *q)
         unsigned long flags;
 
         spin_lock_irqsave(q->queue_lock, flags);
-        __blk_run_queue(q, false);
+        __blk_run_queue(q);
         spin_unlock_irqrestore(q->queue_lock, flags);
 }
 EXPORT_SYMBOL(blk_run_queue);
@@ -977,7 +991,7 @@ void blk_insert_request(struct request_queue *q, struct request *rq,
                 blk_queue_end_tag(q, rq);
 
         add_acct_request(q, rq, where);
-        __blk_run_queue(q, false);
+        __blk_run_queue(q);
         spin_unlock_irqrestore(q->queue_lock, flags);
 }
 EXPORT_SYMBOL(blk_insert_request);
@@ -1321,7 +1335,7 @@ get_rq:
         } else {
                 spin_lock_irq(q->queue_lock);
                 add_acct_request(q, req, where);
-                __blk_run_queue(q, false);
+                __blk_run_queue(q);
 out_unlock:
                 spin_unlock_irq(q->queue_lock);
         }
@@ -2638,6 +2652,7 @@ void blk_start_plug(struct blk_plug *plug)
 
         plug->magic = PLUG_MAGIC;
         INIT_LIST_HEAD(&plug->list);
+        INIT_LIST_HEAD(&plug->cb_list);
         plug->should_sort = 0;
 
         /*
@@ -2670,12 +2685,41 @@ static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
  */
 static void queue_unplugged(struct request_queue *q, unsigned int depth,
                             bool from_schedule)
+        __releases(q->queue_lock)
 {
         trace_block_unplug(q, depth, !from_schedule);
-        __blk_run_queue(q, from_schedule);
 
-        if (q->unplugged_fn)
-                q->unplugged_fn(q);
+        /*
+         * If we are punting this to kblockd, then we can safely drop
+         * the queue_lock before waking kblockd (which needs to take
+         * this lock).
+         */
+        if (from_schedule) {
+                spin_unlock(q->queue_lock);
+                blk_run_queue_async(q);
+        } else {
+                __blk_run_queue(q);
+                spin_unlock(q->queue_lock);
+        }
+
+}
+
+static void flush_plug_callbacks(struct blk_plug *plug)
+{
+        LIST_HEAD(callbacks);
+
+        if (list_empty(&plug->cb_list))
+                return;
+
+        list_splice_init(&plug->cb_list, &callbacks);
+
+        while (!list_empty(&callbacks)) {
+                struct blk_plug_cb *cb = list_first_entry(&callbacks,
+                                                          struct blk_plug_cb,
+                                                          list);
+                list_del(&cb->list);
+                cb->callback(cb);
+        }
 }
 
 void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
@@ -2688,6 +2732,7 @@ void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
 
         BUG_ON(plug->magic != PLUG_MAGIC);
 
+        flush_plug_callbacks(plug);
         if (list_empty(&plug->list))
                 return;
 
@@ -2712,10 +2757,11 @@ void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
                 BUG_ON(!(rq->cmd_flags & REQ_ON_PLUG));
                 BUG_ON(!rq->q);
                 if (rq->q != q) {
-                        if (q) {
+                        /*
+                         * This drops the queue lock
+                         */
+                        if (q)
                                 queue_unplugged(q, depth, from_schedule);
-                                spin_unlock(q->queue_lock);
-                        }
                         q = rq->q;
                         depth = 0;
                         spin_lock(q->queue_lock);
@@ -2733,10 +2779,11 @@ void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
                 depth++;
         }
 
-        if (q) {
+        /*
+         * This drops the queue lock
+         */
+        if (q)
                 queue_unplugged(q, depth, from_schedule);
-                spin_unlock(q->queue_lock);
-        }
 
         local_irq_restore(flags);
 }
diff --git a/block/blk-exec.c b/block/blk-exec.c
index 7482b7fa863b..81e31819a597 100644
--- a/block/blk-exec.c
+++ b/block/blk-exec.c
@@ -55,7 +55,7 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
         WARN_ON(irqs_disabled());
         spin_lock_irq(q->queue_lock);
         __elv_add_request(q, rq, where);
-        __blk_run_queue(q, false);
+        __blk_run_queue(q);
         /* the queue is stopped so it won't be plugged+unplugged */
         if (rq->cmd_type == REQ_TYPE_PM_RESUME)
                 q->request_fn(q);
diff --git a/block/blk-flush.c b/block/blk-flush.c
index eba4a2790c6c..6c9b5e189e62 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -218,7 +218,7 @@ static void flush_end_io(struct request *flush_rq, int error)
          * request_fn may confuse the driver.  Always use kblockd.
          */
         if (queued)
-                __blk_run_queue(q, true);
+                blk_run_queue_async(q);
 }
 
 /**
@@ -274,7 +274,7 @@ static void flush_data_end_io(struct request *rq, int error)
          * the comment in flush_end_io().
          */
         if (blk_flush_complete_seq(rq, REQ_FSEQ_DATA, error))
-                __blk_run_queue(q, true);
+                blk_run_queue_async(q);
 }
 
 /**
diff --git a/block/blk-settings.c b/block/blk-settings.c
index eb949045bb12..1fa769293597 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -790,22 +790,6 @@ void blk_queue_flush(struct request_queue *q, unsigned int flush)
 }
 EXPORT_SYMBOL_GPL(blk_queue_flush);
 
-/**
- * blk_queue_unplugged - register a callback for an unplug event
- * @q:          the request queue for the device
- * @fn:         the function to call
- *
- * Some stacked drivers may need to know when IO is dispatched on an
- * unplug event. By registrering a callback here, they will be notified
- * when someone flushes their on-stack queue plug. The function will be
- * called with the queue lock held.
- */
-void blk_queue_unplugged(struct request_queue *q, unplugged_fn *fn)
-{
-        q->unplugged_fn = fn;
-}
-EXPORT_SYMBOL(blk_queue_unplugged);
-
 static int __init blk_settings_init(void)
 {
         blk_max_low_pfn = max_low_pfn - 1;
diff --git a/block/blk.h b/block/blk.h
index 61263463e38e..c9df8fc3c999 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -22,6 +22,7 @@ void blk_rq_timed_out_timer(unsigned long data);
 void blk_delete_timer(struct request *);
 void blk_add_timer(struct request *);
 void __generic_unplug_device(struct request_queue *);
+void blk_run_queue_async(struct request_queue *q);
 
 /*
  * Internal atomic flags for request handling
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 3be881ec95ad..46b0a1d1d925 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -3368,7 +3368,7 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                             cfqd->busy_queues > 1) {
                                 cfq_del_timer(cfqd, cfqq);
                                 cfq_clear_cfqq_wait_request(cfqq);
-                                __blk_run_queue(cfqd->queue, false);
+                                __blk_run_queue(cfqd->queue);
                         } else {
                                 cfq_blkiocg_update_idle_time_stats(
                                                 &cfqq->cfqg->blkg);
@@ -3383,7 +3383,7 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                  * this new queue is RT and the current one is BE
                  */
                 cfq_preempt_queue(cfqd, cfqq);
-                __blk_run_queue(cfqd->queue, false);
+                __blk_run_queue(cfqd->queue);
         }
 }
 
@@ -3743,7 +3743,7 @@ static void cfq_kick_queue(struct work_struct *work)
         struct request_queue *q = cfqd->queue;
 
         spin_lock_irq(q->queue_lock);
-        __blk_run_queue(cfqd->queue, false);
+        __blk_run_queue(cfqd->queue);
         spin_unlock_irq(q->queue_lock);
 }
 
diff --git a/block/elevator.c b/block/elevator.c
index 0cdb4e7ebab4..6f6abc08bb56 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -642,7 +642,7 @@ void elv_quiesce_start(struct request_queue *q)
          */
         elv_drain_elevator(q);
         while (q->rq.elvpriv) {
-                __blk_run_queue(q, false);
+                __blk_run_queue(q);
                 spin_unlock_irq(q->queue_lock);
                 msleep(10);
                 spin_lock_irq(q->queue_lock);
@@ -695,7 +695,7 @@ void __elv_add_request(struct request_queue *q, struct request *rq, int where)
                  *   with anything.  There's no point in delaying queue
                  *   processing.
                  */
-                __blk_run_queue(q, false);
+                __blk_run_queue(q);
                 break;
 
         case ELEVATOR_INSERT_SORT_MERGE:
diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 5ef136cdba91..e5d8904fc8f6 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -390,13 +390,6 @@ static int raid_is_congested(struct dm_target_callbacks *cb, int bits)
         return md_raid5_congested(&rs->md, bits);
 }
 
-static void raid_unplug(struct dm_target_callbacks *cb)
-{
-        struct raid_set *rs = container_of(cb, struct raid_set, callbacks);
-
-        md_raid5_kick_device(rs->md.private);
-}
-
 /*
  * Construct a RAID4/5/6 mapping:
  * Args:
@@ -487,7 +480,6 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
         }
 
         rs->callbacks.congested_fn = raid_is_congested;
-        rs->callbacks.unplug_fn = raid_unplug;
         dm_table_add_target_callbacks(ti->table, &rs->callbacks);
 
         return 0;
diff --git a/drivers/md/md.c b/drivers/md/md.c
index b12b3776c0c0..6e853c61d87e 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -447,48 +447,59 @@ EXPORT_SYMBOL(md_flush_request);
 
 /* Support for plugging.
  * This mirrors the plugging support in request_queue, but does not
- * require having a whole queue
+ * require having a whole queue or request structures.
+ * We allocate an md_plug_cb for each md device and each thread it gets
+ * plugged on.  This links tot the private plug_handle structure in the
+ * personality data where we keep a count of the number of outstanding
+ * plugs so other code can see if a plug is active.
  */
-static void plugger_work(struct work_struct *work)
-{
-        struct plug_handle *plug =
-                container_of(work, struct plug_handle, unplug_work);
-        plug->unplug_fn(plug);
-}
-static void plugger_timeout(unsigned long data)
-{
-        struct plug_handle *plug = (void *)data;
-        kblockd_schedule_work(NULL, &plug->unplug_work);
-}
-void plugger_init(struct plug_handle *plug,
-                  void (*unplug_fn)(struct plug_handle *))
-{
-        plug->unplug_flag = 0;
-        plug->unplug_fn = unplug_fn;
-        init_timer(&plug->unplug_timer);
-        plug->unplug_timer.function = plugger_timeout;
-        plug->unplug_timer.data = (unsigned long)plug;
-        INIT_WORK(&plug->unplug_work, plugger_work);
-}
-EXPORT_SYMBOL_GPL(plugger_init);
+struct md_plug_cb {
+        struct blk_plug_cb cb;
+        mddev_t *mddev;
+};
 
-void plugger_set_plug(struct plug_handle *plug)
+static void plugger_unplug(struct blk_plug_cb *cb)
 {
-        if (!test_and_set_bit(PLUGGED_FLAG, &plug->unplug_flag))
-                mod_timer(&plug->unplug_timer, jiffies + msecs_to_jiffies(3)+1);
+        struct md_plug_cb *mdcb = container_of(cb, struct md_plug_cb, cb);
+        if (atomic_dec_and_test(&mdcb->mddev->plug_cnt))
+                md_wakeup_thread(mdcb->mddev->thread);
+        kfree(mdcb);
 }
-EXPORT_SYMBOL_GPL(plugger_set_plug);
 
-int plugger_remove_plug(struct plug_handle *plug)
+/* Check that an unplug wakeup will come shortly.
+ * If not, wakeup the md thread immediately
+ */
+int mddev_check_plugged(mddev_t *mddev)
 {
-        if (test_and_clear_bit(PLUGGED_FLAG, &plug->unplug_flag)) {
-                del_timer(&plug->unplug_timer);
-                return 1;
-        } else
+        struct blk_plug *plug = current->plug;
+        struct md_plug_cb *mdcb;
+
+        if (!plug)
+                return 0;
+
+        list_for_each_entry(mdcb, &plug->cb_list, cb.list) {
+                if (mdcb->cb.callback == plugger_unplug &&
+                    mdcb->mddev == mddev) {
+                        /* Already on the list, move to top */
+                        if (mdcb != list_first_entry(&plug->cb_list,
+                                                    struct md_plug_cb,
+                                                    cb.list))
+                                list_move(&mdcb->cb.list, &plug->cb_list);
+                        return 1;
+                }
+        }
+        /* Not currently on the callback list */
+        mdcb = kmalloc(sizeof(*mdcb), GFP_ATOMIC);
+        if (!mdcb)
                 return 0;
-}
-EXPORT_SYMBOL_GPL(plugger_remove_plug);
 
+        mdcb->mddev = mddev;
+        mdcb->cb.callback = plugger_unplug;
+        atomic_inc(&mddev->plug_cnt);
+        list_add(&mdcb->cb.list, &plug->cb_list);
+        return 1;
+}
+EXPORT_SYMBOL_GPL(mddev_check_plugged);
 
 static inline mddev_t *mddev_get(mddev_t *mddev)
 {
@@ -538,6 +549,7 @@ void mddev_init(mddev_t *mddev)
         atomic_set(&mddev->active, 1);
         atomic_set(&mddev->openers, 0);
         atomic_set(&mddev->active_io, 0);
+        atomic_set(&mddev->plug_cnt, 0);
         spin_lock_init(&mddev->write_lock);
         atomic_set(&mddev->flush_pending, 0);
         init_waitqueue_head(&mddev->sb_wait);
@@ -4723,7 +4735,6 @@ static void md_clean(mddev_t *mddev)
         mddev->bitmap_info.chunksize = 0;
         mddev->bitmap_info.daemon_sleep = 0;
         mddev->bitmap_info.max_write_behind = 0;
-        mddev->plug = NULL;
 }
 
 static void __md_stop_writes(mddev_t *mddev)
@@ -6688,12 +6699,6 @@ int md_allow_write(mddev_t *mddev)
 }
 EXPORT_SYMBOL_GPL(md_allow_write);
 
-void md_unplug(mddev_t *mddev)
-{
-        if (mddev->plug)
-                mddev->plug->unplug_fn(mddev->plug);
-}
-
 #define SYNC_MARKS      10
 #define SYNC_MARK_STEP  (3*HZ)
 void md_do_sync(mddev_t *mddev)
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 52b407369e13..0b1fd3f1d85b 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -29,26 +29,6 @@
 typedef struct mddev_s mddev_t;
 typedef struct mdk_rdev_s mdk_rdev_t;
 
-/* generic plugging support - like that provided with request_queue,
- * but does not require a request_queue
- */
-struct plug_handle {
-        void                    (*unplug_fn)(struct plug_handle *);
-        struct timer_list       unplug_timer;
-        struct work_struct      unplug_work;
-        unsigned long           unplug_flag;
-};
-#define PLUGGED_FLAG 1
-void plugger_init(struct plug_handle *plug,
-                  void (*unplug_fn)(struct plug_handle *));
-void plugger_set_plug(struct plug_handle *plug);
-int plugger_remove_plug(struct plug_handle *plug);
-static inline void plugger_flush(struct plug_handle *plug)
-{
-        del_timer_sync(&plug->unplug_timer);
-        cancel_work_sync(&plug->unplug_work);
-}
-
 /*
  * MD's 'extended' device
  */
@@ -199,6 +179,9 @@ struct mddev_s
         int                             delta_disks, new_level, new_layout;
         int                             new_chunk_sectors;
 
+        atomic_t                        plug_cnt;       /* If device is expecting
+                                                         * more bios soon.
+                                                         */
         struct mdk_thread_s             *thread;        /* management thread */
         struct mdk_thread_s             *sync_thread;   /* doing resync or reconstruct */
         sector_t                        curr_resync;    /* last block scheduled */
@@ -336,7 +319,6 @@ struct mddev_s
         struct list_head                all_mddevs;
 
         struct attribute_group          *to_remove;
-        struct plug_handle              *plug; /* if used by personality */
 
         struct bio_set                  *bio_set;
 
@@ -516,7 +498,6 @@ extern int md_integrity_register(mddev_t *mddev);
 extern void md_integrity_add_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
 extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);
 extern void restore_bitmap_write_access(struct file *file);
-extern void md_unplug(mddev_t *mddev);
 
 extern void mddev_init(mddev_t *mddev);
 extern int md_run(mddev_t *mddev);
@@ -530,4 +511,5 @@ extern struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask,
                                    mddev_t *mddev);
 extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
                                    mddev_t *mddev);
+extern int mddev_check_plugged(mddev_t *mddev);
 #endif /* _MD_MD_H */
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index c2a21ae56d97..2b7a7ff401dc 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -565,12 +565,6 @@ static void flush_pending_writes(conf_t *conf)
                 spin_unlock_irq(&conf->device_lock);
 }
 
-static void md_kick_device(mddev_t *mddev)
-{
-        blk_flush_plug(current);
-        md_wakeup_thread(mddev->thread);
-}
-
 /* Barriers....
  * Sometimes we need to suspend IO while we do something else,
  * either some resync/recovery, or reconfigure the array.
@@ -600,7 +594,7 @@ static void raise_barrier(conf_t *conf)
 
         /* Wait until no block IO is waiting */
         wait_event_lock_irq(conf->wait_barrier, !conf->nr_waiting,
-                            conf->resync_lock, md_kick_device(conf->mddev));
+                            conf->resync_lock, );
 
         /* block any new IO from starting */
         conf->barrier++;
@@ -608,7 +602,7 @@ static void raise_barrier(conf_t *conf)
         /* Now wait for all pending IO to complete */
         wait_event_lock_irq(conf->wait_barrier,
                             !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
-                            conf->resync_lock, md_kick_device(conf->mddev));
+                            conf->resync_lock, );
 
         spin_unlock_irq(&conf->resync_lock);
 }
@@ -630,7 +624,7 @@ static void wait_barrier(conf_t *conf)
                 conf->nr_waiting++;
                 wait_event_lock_irq(conf->wait_barrier, !conf->barrier,
                                     conf->resync_lock,
-                                    md_kick_device(conf->mddev));
+                                    );
                 conf->nr_waiting--;
         }
         conf->nr_pending++;
@@ -666,8 +660,7 @@ static void freeze_array(conf_t *conf)
         wait_event_lock_irq(conf->wait_barrier,
                             conf->nr_pending == conf->nr_queued+1,
                             conf->resync_lock,
-                            ({ flush_pending_writes(conf);
-                               md_kick_device(conf->mddev); }));
+                            flush_pending_writes(conf));
         spin_unlock_irq(&conf->resync_lock);
 }
 static void unfreeze_array(conf_t *conf)
@@ -729,6 +722,7 @@ static int make_request(mddev_t *mddev, struct bio * bio)
         const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
         const unsigned long do_flush_fua = (bio->bi_rw & (REQ_FLUSH | REQ_FUA));
         mdk_rdev_t *blocked_rdev;
+        int plugged;
 
         /*
          * Register the new request and wait if the reconstruction
@@ -820,6 +814,8 @@ static int make_request(mddev_t *mddev, struct bio * bio)
          * inc refcount on their rdev.  Record them by setting
          * bios[x] to bio
          */
+        plugged = mddev_check_plugged(mddev);
+
         disks = conf->raid_disks;
  retry_write:
         blocked_rdev = NULL;
@@ -925,7 +921,7 @@ static int make_request(mddev_t *mddev, struct bio * bio)
         /* In case raid1d snuck in to freeze_array */
         wake_up(&conf->wait_barrier);
 
-        if (do_sync || !bitmap)
+        if (do_sync || !bitmap || !plugged)
                 md_wakeup_thread(mddev->thread);
 
         return 0;
@@ -1516,13 +1512,16 @@ static void raid1d(mddev_t *mddev)
         conf_t *conf = mddev->private;
         struct list_head *head = &conf->retry_list;
         mdk_rdev_t *rdev;
+        struct blk_plug plug;
 
         md_check_recovery(mddev);
-        
+
+        blk_start_plug(&plug);
         for (;;) {
                 char b[BDEVNAME_SIZE];
 
-                flush_pending_writes(conf);
+                if (atomic_read(&mddev->plug_cnt) == 0)
+                        flush_pending_writes(conf);
 
                 spin_lock_irqsave(&conf->device_lock, flags);
                 if (list_empty(head)) {
@@ -1593,6 +1592,7 @@ static void raid1d(mddev_t *mddev)
                 }
                 cond_resched();
         }
+        blk_finish_plug(&plug);
 }
 
 
@@ -2039,7 +2039,6 @@ static int stop(mddev_t *mddev)
 
         md_unregister_thread(mddev->thread);
         mddev->thread = NULL;
-        blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
         if (conf->r1bio_pool)
                 mempool_destroy(conf->r1bio_pool);
         kfree(conf->mirrors);
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 2da83d566592..8e9462626ec5 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -634,12 +634,6 @@ static void flush_pending_writes(conf_t *conf)
                 spin_unlock_irq(&conf->device_lock);
 }
 
-static void md_kick_device(mddev_t *mddev)
-{
-        blk_flush_plug(current);
-        md_wakeup_thread(mddev->thread);
-}
-
 /* Barriers....
  * Sometimes we need to suspend IO while we do something else,
  * either some resync/recovery, or reconfigure the array.
@@ -669,15 +663,15 @@ static void raise_barrier(conf_t *conf, int force)
 
         /* Wait until no block IO is waiting (unless 'force') */
         wait_event_lock_irq(conf->wait_barrier, force || !conf->nr_waiting,
-                            conf->resync_lock, md_kick_device(conf->mddev));
+                            conf->resync_lock, );
 
         /* block any new IO from starting */
         conf->barrier++;
 
-        /* No wait for all pending IO to complete */
+        /* Now wait for all pending IO to complete */
         wait_event_lock_irq(conf->wait_barrier,
                             !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
-                            conf->resync_lock, md_kick_device(conf->mddev));
+                            conf->resync_lock, );
 
         spin_unlock_irq(&conf->resync_lock);
 }
@@ -698,7 +692,7 @@ static void wait_barrier(conf_t *conf)
                 conf->nr_waiting++;
                 wait_event_lock_irq(conf->wait_barrier, !conf->barrier,
                                     conf->resync_lock,
-                                    md_kick_device(conf->mddev));
+                                    );
                 conf->nr_waiting--;
         }
         conf->nr_pending++;
@@ -734,8 +728,8 @@ static void freeze_array(conf_t *conf)
         wait_event_lock_irq(conf->wait_barrier,
                             conf->nr_pending == conf->nr_queued+1,
                             conf->resync_lock,
-                            ({ flush_pending_writes(conf);
-                               md_kick_device(conf->mddev); }));
+                            flush_pending_writes(conf));
+
         spin_unlock_irq(&conf->resync_lock);
 }
 
@@ -762,6 +756,7 @@ static int make_request(mddev_t *mddev, struct bio * bio)
         const unsigned long do_fua = (bio->bi_rw & REQ_FUA);
         unsigned long flags;
         mdk_rdev_t *blocked_rdev;
+        int plugged;
 
         if (unlikely(bio->bi_rw & REQ_FLUSH)) {
                 md_flush_request(mddev, bio);
@@ -870,6 +865,8 @@ static int make_request(mddev_t *mddev, struct bio * bio)
          * inc refcount on their rdev.  Record them by setting
          * bios[x] to bio
          */
+        plugged = mddev_check_plugged(mddev);
+
         raid10_find_phys(conf, r10_bio);
  retry_write:
         blocked_rdev = NULL;
@@ -946,9 +943,8 @@ static int make_request(mddev_t *mddev, struct bio * bio)
         /* In case raid10d snuck in to freeze_array */
         wake_up(&conf->wait_barrier);
 
-        if (do_sync || !mddev->bitmap)
+        if (do_sync || !mddev->bitmap || !plugged)
                 md_wakeup_thread(mddev->thread);
-
         return 0;
 }
 
@@ -1640,9 +1636,11 @@ static void raid10d(mddev_t *mddev)
         conf_t *conf = mddev->private;
         struct list_head *head = &conf->retry_list;
         mdk_rdev_t *rdev;
+        struct blk_plug plug;
 
         md_check_recovery(mddev);
 
+        blk_start_plug(&plug);
         for (;;) {
                 char b[BDEVNAME_SIZE];
 
@@ -1716,6 +1714,7 @@ static void raid10d(mddev_t *mddev)
                 }
                 cond_resched();
         }
+        blk_finish_plug(&plug);
 }
 
 
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index e867ee42b152..f301e6ae220c 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -27,12 +27,12 @@
  *
  * We group bitmap updates into batches.  Each batch has a number.
  * We may write out several batches at once, but that isn't very important.
- * conf->bm_write is the number of the last batch successfully written.
- * conf->bm_flush is the number of the last batch that was closed to
+ * conf->seq_write is the number of the last batch successfully written.
+ * conf->seq_flush is the number of the last batch that was closed to
  *    new additions.
  * When we discover that we will need to write to any block in a stripe
  * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
- * the number of the batch it will be in. This is bm_flush+1.
+ * the number of the batch it will be in. This is seq_flush+1.
  * When we are ready to do a write, if that batch hasn't been written yet,
  *   we plug the array and queue the stripe for later.
  * When an unplug happens, we increment bm_flush, thus closing the current
@@ -199,14 +199,12 @@ static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
                 BUG_ON(!list_empty(&sh->lru));
                 BUG_ON(atomic_read(&conf->active_stripes)==0);
                 if (test_bit(STRIPE_HANDLE, &sh->state)) {
-                        if (test_bit(STRIPE_DELAYED, &sh->state)) {
+                        if (test_bit(STRIPE_DELAYED, &sh->state))
                                 list_add_tail(&sh->lru, &conf->delayed_list);
-                                plugger_set_plug(&conf->plug);
-                        } else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
-                                   sh->bm_seq - conf->seq_write > 0) {
+                        else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
+                                   sh->bm_seq - conf->seq_write > 0)
                                 list_add_tail(&sh->lru, &conf->bitmap_list);
-                                plugger_set_plug(&conf->plug);
-                        } else {
+                        else {
                                 clear_bit(STRIPE_BIT_DELAY, &sh->state);
                                 list_add_tail(&sh->lru, &conf->handle_list);
                         }
@@ -461,7 +459,7 @@ get_active_stripe(raid5_conf_t *conf, sector_t sector,
                                                      < (conf->max_nr_stripes *3/4)
                                                      || !conf->inactive_blocked),
                                                     conf->device_lock,
-                                                    md_raid5_kick_device(conf));
+                                                    );
                                 conf->inactive_blocked = 0;
                         } else
                                 init_stripe(sh, sector, previous);
@@ -1470,7 +1468,7 @@ static int resize_stripes(raid5_conf_t *conf, int newsize)
                 wait_event_lock_irq(conf->wait_for_stripe,
                                     !list_empty(&conf->inactive_list),
                                     conf->device_lock,
-                                    blk_flush_plug(current));
+                                    );
                 osh = get_free_stripe(conf);
                 spin_unlock_irq(&conf->device_lock);
                 atomic_set(&nsh->count, 1);
@@ -3623,8 +3621,7 @@ static void raid5_activate_delayed(raid5_conf_t *conf)
                                 atomic_inc(&conf->preread_active_stripes);
                         list_add_tail(&sh->lru, &conf->hold_list);
                 }
-        } else
-                plugger_set_plug(&conf->plug);
+        }
 }
 
 static void activate_bit_delay(raid5_conf_t *conf)
@@ -3641,21 +3638,6 @@ static void activate_bit_delay(raid5_conf_t *conf)
         }
 }
 
-void md_raid5_kick_device(raid5_conf_t *conf)
-{
-        blk_flush_plug(current);
-        raid5_activate_delayed(conf);
-        md_wakeup_thread(conf->mddev->thread);
-}
-EXPORT_SYMBOL_GPL(md_raid5_kick_device);
-
-static void raid5_unplug(struct plug_handle *plug)
-{
-        raid5_conf_t *conf = container_of(plug, raid5_conf_t, plug);
-
-        md_raid5_kick_device(conf);
-}
-
 int md_raid5_congested(mddev_t *mddev, int bits)
 {
         raid5_conf_t *conf = mddev->private;
@@ -3945,6 +3927,7 @@ static int make_request(mddev_t *mddev, struct bio * bi)
         struct stripe_head *sh;
         const int rw = bio_data_dir(bi);
         int remaining;
+        int plugged;
 
         if (unlikely(bi->bi_rw & REQ_FLUSH)) {
                 md_flush_request(mddev, bi);
@@ -3963,6 +3946,7 @@ static int make_request(mddev_t *mddev, struct bio * bi)
         bi->bi_next = NULL;
         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
 
+        plugged = mddev_check_plugged(mddev);
         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
                 DEFINE_WAIT(w);
                 int disks, data_disks;
@@ -4057,7 +4041,7 @@ static int make_request(mddev_t *mddev, struct bio * bi)
                                  * add failed due to overlap.  Flush everything
                                  * and wait a while
                                  */
-                                md_raid5_kick_device(conf);
+                                md_wakeup_thread(mddev->thread);
                                 release_stripe(sh);
                                 schedule();
                                 goto retry;
@@ -4077,6 +4061,9 @@ static int make_request(mddev_t *mddev, struct bio * bi)
                 }
                         
         }
+        if (!plugged)
+                md_wakeup_thread(mddev->thread);
+
         spin_lock_irq(&conf->device_lock);
         remaining = raid5_dec_bi_phys_segments(bi);
         spin_unlock_irq(&conf->device_lock);
@@ -4478,24 +4465,30 @@ static void raid5d(mddev_t *mddev)
         struct stripe_head *sh;
         raid5_conf_t *conf = mddev->private;
         int handled;
+        struct blk_plug plug;
 
         pr_debug("+++ raid5d active\n");
 
         md_check_recovery(mddev);
 
+        blk_start_plug(&plug);
         handled = 0;
         spin_lock_irq(&conf->device_lock);
         while (1) {
                 struct bio *bio;
 
-                if (conf->seq_flush != conf->seq_write) {
-                        int seq = conf->seq_flush;
+                if (atomic_read(&mddev->plug_cnt) == 0 &&
+                    !list_empty(&conf->bitmap_list)) {
+                        /* Now is a good time to flush some bitmap updates */
+                        conf->seq_flush++;
                         spin_unlock_irq(&conf->device_lock);
                         bitmap_unplug(mddev->bitmap);
                         spin_lock_irq(&conf->device_lock);
-                        conf->seq_write = seq;
+                        conf->seq_write = conf->seq_flush;
                         activate_bit_delay(conf);
                 }
+                if (atomic_read(&mddev->plug_cnt) == 0)
+                        raid5_activate_delayed(conf);
 
                 while ((bio = remove_bio_from_retry(conf))) {
                         int ok;
@@ -4525,6 +4518,7 @@ static void raid5d(mddev_t *mddev)
         spin_unlock_irq(&conf->device_lock);
 
         async_tx_issue_pending_all();
+        blk_finish_plug(&plug);
 
         pr_debug("--- raid5d inactive\n");
 }
@@ -5141,8 +5135,6 @@ static int run(mddev_t *mddev)
                        mdname(mddev));
         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
 
-        plugger_init(&conf->plug, raid5_unplug);
-        mddev->plug = &conf->plug;
         if (mddev->queue) {
                 int chunk_size;
                 /* read-ahead size must cover two whole stripes, which
@@ -5192,7 +5184,6 @@ static int stop(mddev_t *mddev)
         mddev->thread = NULL;
         if (mddev->queue)
                 mddev->queue->backing_dev_info.congested_fn = NULL;
-        plugger_flush(&conf->plug); /* the unplug fn references 'conf'*/
         free_conf(conf);
         mddev->private = NULL;
         mddev->to_remove = &raid5_attrs_group;
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 8d563a4f022a..3ca77a2613ba 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -400,8 +400,6 @@ struct raid5_private_data {
                                             * Cleared when a sync completes.
                                             */
 
-        struct plug_handle      plug;
-
         /* per cpu variables */
         struct raid5_percpu {
                 struct page     *spare_page; /* Used when checking P/Q in raid6 */
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 6d5c7ff43f5b..ab55c2fa7ce2 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -443,7 +443,7 @@ static void scsi_run_queue(struct request_queue *q)
                                         &sdev->request_queue->queue_flags);
                 if (flagset)
                         queue_flag_set(QUEUE_FLAG_REENTER, sdev->request_queue);
-                __blk_run_queue(sdev->request_queue, false);
+                __blk_run_queue(sdev->request_queue);
                 if (flagset)
                         queue_flag_clear(QUEUE_FLAG_REENTER, sdev->request_queue);
                 spin_unlock(sdev->request_queue->queue_lock);
diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
index fdf3fa639056..28c33506e4ad 100644
--- a/drivers/scsi/scsi_transport_fc.c
+++ b/drivers/scsi/scsi_transport_fc.c
@@ -3829,7 +3829,7 @@ fc_bsg_goose_queue(struct fc_rport *rport)
                   !test_bit(QUEUE_FLAG_REENTER, &rport->rqst_q->queue_flags);
         if (flagset)
                 queue_flag_set(QUEUE_FLAG_REENTER, rport->rqst_q);
-        __blk_run_queue(rport->rqst_q, false);
+        __blk_run_queue(rport->rqst_q);
         if (flagset)
                 queue_flag_clear(QUEUE_FLAG_REENTER, rport->rqst_q);
         spin_unlock_irqrestore(rport->rqst_q->queue_lock, flags);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index ec0357d8c4a5..cbbfd98ad4a3 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -196,7 +196,6 @@ typedef void (request_fn_proc) (struct request_queue *q);
 typedef int (make_request_fn) (struct request_queue *q, struct bio *bio);
 typedef int (prep_rq_fn) (struct request_queue *, struct request *);
 typedef void (unprep_rq_fn) (struct request_queue *, struct request *);
-typedef void (unplugged_fn) (struct request_queue *);
 
 struct bio_vec;
 struct bvec_merge_data {
@@ -284,7 +283,6 @@ struct request_queue
         rq_timed_out_fn         *rq_timed_out_fn;
         dma_drain_needed_fn     *dma_drain_needed;
         lld_busy_fn             *lld_busy_fn;
-        unplugged_fn            *unplugged_fn;
 
         /*
          * Dispatch queue sorting
@@ -699,7 +697,7 @@ extern void blk_start_queue(struct request_queue *q);
 extern void blk_stop_queue(struct request_queue *q);
 extern void blk_sync_queue(struct request_queue *q);
 extern void __blk_stop_queue(struct request_queue *q);
-extern void __blk_run_queue(struct request_queue *q, bool force_kblockd);
+extern void __blk_run_queue(struct request_queue *q);
 extern void blk_run_queue(struct request_queue *);
 extern int blk_rq_map_user(struct request_queue *, struct request *,
                            struct rq_map_data *, void __user *, unsigned long,
@@ -843,7 +841,6 @@ extern void blk_queue_dma_alignment(struct request_queue *, int);
 extern void blk_queue_update_dma_alignment(struct request_queue *, int);
 extern void blk_queue_softirq_done(struct request_queue *, softirq_done_fn *);
 extern void blk_queue_rq_timed_out(struct request_queue *, rq_timed_out_fn *);
-extern void blk_queue_unplugged(struct request_queue *, unplugged_fn *);
 extern void blk_queue_rq_timeout(struct request_queue *, unsigned int);
 extern void blk_queue_flush(struct request_queue *q, unsigned int flush);
 extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);
@@ -860,8 +857,13 @@ extern void blk_put_queue(struct request_queue *);
 struct blk_plug {
         unsigned long magic;
         struct list_head list;
+        struct list_head cb_list;
         unsigned int should_sort;
 };
+struct blk_plug_cb {
+        struct list_head list;
+        void (*callback)(struct blk_plug_cb *);
+};
 
 extern void blk_start_plug(struct blk_plug *);
 extern void blk_finish_plug(struct blk_plug *);
@@ -887,7 +889,7 @@ static inline bool blk_needs_flush_plug(struct task_struct *tsk)
 {
         struct blk_plug *plug = tsk->plug;
 
-        return plug && !list_empty(&plug->list);
+        return plug && (!list_empty(&plug->list) || !list_empty(&plug->cb_list));
 }
 
 /*
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index e2768834f397..32a4423710f5 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -197,7 +197,6 @@ struct dm_target {
 struct dm_target_callbacks {
         struct list_head list;
         int (*congested_fn) (struct dm_target_callbacks *, int);
-        void (*unplug_fn)(struct dm_target_callbacks *);
 };
 
 int dm_register_target(struct target_type *t);