md - remove old plugging code.

md has some plugging infrastructure for RAID5 to use because the
normal plugging infrastructure required a 'request_queue', and when
called from dm, RAID5 doesn't have one of those available.

This relied on the ->unplug_fn callback which doesn't exist any more.

So remove all of that code, both in md and raid5.  Subsequent patches
with restore the plugging functionality.
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/md.c

@@ -445,50 +445,6 @@ void md_flush_request(mddev_t *mddev, struct bio *bio)
 }
 EXPORT_SYMBOL(md_flush_request);
 
-/* Support for plugging.
- * This mirrors the plugging support in request_queue, but does not
- * require having a whole queue
- */
-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);
-
-void plugger_set_plug(struct plug_handle *plug)
-{
-	if (!test_and_set_bit(PLUGGED_FLAG, &plug->unplug_flag))
-		mod_timer(&plug->unplug_timer, jiffies + msecs_to_jiffies(3)+1);
-}
-EXPORT_SYMBOL_GPL(plugger_set_plug);
-
-int plugger_remove_plug(struct plug_handle *plug)
-{
-	if (test_and_clear_bit(PLUGGED_FLAG, &plug->unplug_flag)) {
-		del_timer(&plug->unplug_timer);
-		return 1;
-	} else
-		return 0;
-}
-EXPORT_SYMBOL_GPL(plugger_remove_plug);
-
 
 static inline mddev_t *mddev_get(mddev_t *mddev)
 {
@@ -4723,7 +4679,6 @@ 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 +6643,6 @@ 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)

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
  */
@@ -336,7 +316,6 @@ 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 +495,6 @@ 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);

drivers/md/raid5.c

@@ -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));
+						    md_wakeup_thread(conf->mddev->thread));
 				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;
@@ -4057,7 +4039,7 @@ 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;
@@ -5144,8 +5126,6 @@ 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
@@ -5195,7 +5175,6 @@ 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;

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 */