Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block

* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
  block: restore multiple bd_link_disk_holder() support
  block cfq: compensate preempted queue even if it has no slice assigned
  block cfq: make queue preempt work for queues from different workload

block/cfq-iosched.c

@@ -598,8 +598,8 @@ cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
 	return cfq_target_latency * cfqg->weight / st->total_weight;
 }
 
-static inline void
-cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+static inline unsigned
+cfq_scaled_group_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
 	unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
 	if (cfqd->cfq_latency) {
@@ -625,6 +625,14 @@ cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 				    low_slice);
 		}
 	}
+	return slice;
+}
+
+static inline void
+cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+	unsigned slice = cfq_scaled_group_slice(cfqd, cfqq);
+
 	cfqq->slice_start = jiffies;
 	cfqq->slice_end = jiffies + slice;
 	cfqq->allocated_slice = slice;
@@ -1661,7 +1669,10 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 	/*
 	 * store what was left of this slice, if the queue idled/timed out
 	 */
-	if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
+	if (timed_out) {
+		if (cfq_cfqq_slice_new(cfqq))
+			cfqq->slice_resid = cfq_scaled_group_slice(cfqd, cfqq);
+		else
 			cfqq->slice_resid = cfqq->slice_end - jiffies;
 		cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
 	}
@@ -3284,9 +3295,18 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
  */
 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
+	struct cfq_queue *old_cfqq = cfqd->active_queue;
+
 	cfq_log_cfqq(cfqd, cfqq, "preempt");
 	cfq_slice_expired(cfqd, 1);
 
+	/*
+	 * workload type is changed, don't save slice, otherwise preempt
+	 * doesn't happen
+	 */
+	if (cfqq_type(old_cfqq) != cfqq_type(cfqq))
+		cfqq->cfqg->saved_workload_slice = 0;
+
 	/*
 	 * Put the new queue at the front of the of the current list,
 	 * so we know that it will be selected next.

drivers/md/dm-table.c

@@ -350,6 +350,7 @@ static void close_dev(struct dm_dev_internal *d, struct mapped_device *md)
 	if (!d->dm_dev.bdev)
 		return;
 
+	bd_unlink_disk_holder(d->dm_dev.bdev, dm_disk(md));
 	blkdev_put(d->dm_dev.bdev, d->dm_dev.mode | FMODE_EXCL);
 	d->dm_dev.bdev = NULL;
 }

drivers/md/md.c

@@ -1912,6 +1912,7 @@ static void unbind_rdev_from_array(mdk_rdev_t * rdev)
 		MD_BUG();
 		return;
 	}
+	bd_unlink_disk_holder(rdev->bdev, rdev->mddev->gendisk);
 	list_del_rcu(&rdev->same_set);
 	printk(KERN_INFO "md: unbind<%s>\n", bdevname(rdev->bdev,b));
 	rdev->mddev = NULL;

fs/block_dev.c

@@ -432,6 +432,9 @@ static void init_once(void *foo)
 	mutex_init(&bdev->bd_mutex);
 	INIT_LIST_HEAD(&bdev->bd_inodes);
 	INIT_LIST_HEAD(&bdev->bd_list);
+#ifdef CONFIG_SYSFS
+	INIT_LIST_HEAD(&bdev->bd_holder_disks);
+#endif
 	inode_init_once(&ei->vfs_inode);
 	/* Initialize mutex for freeze. */
 	mutex_init(&bdev->bd_fsfreeze_mutex);
@@ -779,6 +782,23 @@ static struct block_device *bd_start_claiming(struct block_device *bdev,
 }
 
 #ifdef CONFIG_SYSFS
+struct bd_holder_disk {
+	struct list_head	list;
+	struct gendisk		*disk;
+	int			refcnt;
+};
+
+static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
+						  struct gendisk *disk)
+{
+	struct bd_holder_disk *holder;
+
+	list_for_each_entry(holder, &bdev->bd_holder_disks, list)
+		if (holder->disk == disk)
+			return holder;
+	return NULL;
+}
+
 static int add_symlink(struct kobject *from, struct kobject *to)
 {
 	return sysfs_create_link(from, to, kobject_name(to));
@@ -794,6 +814,8 @@ static void del_symlink(struct kobject *from, struct kobject *to)
  * @bdev: the claimed slave bdev
  * @disk: the holding disk
  *
+ * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
+ *
  * This functions creates the following sysfs symlinks.
  *
  * - from "slaves" directory of the holder @disk to the claimed @bdev
@@ -817,47 +839,83 @@ static void del_symlink(struct kobject *from, struct kobject *to)
  */
 int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
 {
+	struct bd_holder_disk *holder;
 	int ret = 0;
 
 	mutex_lock(&bdev->bd_mutex);
 
-	WARN_ON_ONCE(!bdev->bd_holder || bdev->bd_holder_disk);
+	WARN_ON_ONCE(!bdev->bd_holder);
 
 	/* FIXME: remove the following once add_disk() handles errors */
 	if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
 		goto out_unlock;
 
+	holder = bd_find_holder_disk(bdev, disk);
+	if (holder) {
+		holder->refcnt++;
+		goto out_unlock;
+	}
+
+	holder = kzalloc(sizeof(*holder), GFP_KERNEL);
+	if (!holder) {
+		ret = -ENOMEM;
+		goto out_unlock;
+	}
+
+	INIT_LIST_HEAD(&holder->list);
+	holder->disk = disk;
+	holder->refcnt = 1;
+
 	ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
 	if (ret)
-		goto out_unlock;
+		goto out_free;
 
 	ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
-	if (ret) {
-		del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
+	if (ret)
+		goto out_del;
+
+	list_add(&holder->list, &bdev->bd_holder_disks);
 	goto out_unlock;
-	}
 
-	bdev->bd_holder_disk = disk;
+out_del:
+	del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
+out_free:
+	kfree(holder);
 out_unlock:
 	mutex_unlock(&bdev->bd_mutex);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(bd_link_disk_holder);
 
-static void bd_unlink_disk_holder(struct block_device *bdev)
+/**
+ * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
+ * @bdev: the calimed slave bdev
+ * @disk: the holding disk
+ *
+ * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
+ *
+ * CONTEXT:
+ * Might sleep.
+ */
+void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
 {
-	struct gendisk *disk = bdev->bd_holder_disk;
+	struct bd_holder_disk *holder;
 
-	bdev->bd_holder_disk = NULL;
-	if (!disk)
-		return;
+	mutex_lock(&bdev->bd_mutex);
 
+	holder = bd_find_holder_disk(bdev, disk);
+
+	if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
 		del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
-	del_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
+		del_symlink(bdev->bd_part->holder_dir,
+			    &disk_to_dev(disk)->kobj);
+		list_del_init(&holder->list);
+		kfree(holder);
+	}
+
+	mutex_unlock(&bdev->bd_mutex);
 }
-#else
-static inline void bd_unlink_disk_holder(struct block_device *bdev)
-{ }
+EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
 #endif
 
 /**
@@ -1380,7 +1438,6 @@ int blkdev_put(struct block_device *bdev, fmode_t mode)
 		 * unblock evpoll if it was a write holder.
 		 */
 		if (bdev_free) {
-			bd_unlink_disk_holder(bdev);
 			if (bdev->bd_write_holder) {
 				disk_unblock_events(bdev->bd_disk);
 				bdev->bd_write_holder = false;

include/linux/fs.h

@@ -666,7 +666,7 @@ struct block_device {
 	int			bd_holders;
 	bool			bd_write_holder;
 #ifdef CONFIG_SYSFS
-	struct gendisk *	bd_holder_disk;	/* for sysfs slave linkng */
+	struct list_head	bd_holder_disks;
 #endif
 	struct block_device *	bd_contains;
 	unsigned		bd_block_size;
@@ -2057,12 +2057,18 @@ extern struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode,
 extern int blkdev_put(struct block_device *bdev, fmode_t mode);
 #ifdef CONFIG_SYSFS
 extern int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk);
+extern void bd_unlink_disk_holder(struct block_device *bdev,
+				  struct gendisk *disk);
 #else
 static inline int bd_link_disk_holder(struct block_device *bdev,
 				      struct gendisk *disk)
 {
 	return 0;
 }
+static inline void bd_unlink_disk_holder(struct block_device *bdev,
+					 struct gendisk *disk)
+{
+}
 #endif
 #endif