[PATCH 1/2] block: unregister holder kobject on late add_disk failure

[Christoph Hellwig <hch@xxxxxx>]

When device_add_disk fails after the registering the delayed holders,
the kobjects for them are leaked.  Fix this by unregistering them for
these failure cases.

Fixes: 89f871af1b26 ("dm: delay registering the gendisk")
Reported-by: Yu Kuai <yukuai1@xxxxxxxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 block/genhd.c          |  4 +++-
 block/holder.c         | 10 ++++++++++
 include/linux/blkdev.h |  4 ++++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/block/genhd.c b/block/genhd.c
index 17b33c62423df..6123005154b2a 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -484,7 +484,7 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
 
 	ret = blk_register_queue(disk);
 	if (ret)
-		goto out_put_slave_dir;
+		goto out_unregister_holders;
 
 	if (!(disk->flags & GENHD_FL_HIDDEN)) {
 		ret = bdi_register(disk->bdi, "%u:%u",
@@ -526,6 +526,8 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
 		bdi_unregister(disk->bdi);
 out_unregister_queue:
 	blk_unregister_queue(disk);
+out_unregister_holders:
+	bd_unregister_all_holders(disk);
 out_put_slave_dir:
 	kobject_put(disk->slave_dir);
 out_put_holder_dir:
diff --git a/block/holder.c b/block/holder.c
index 4923a77ebecdc..b60fca775b055 100644
--- a/block/holder.c
+++ b/block/holder.c
@@ -173,3 +173,13 @@ int bd_register_pending_holders(struct gendisk *disk)
 	mutex_unlock(&disk->open_mutex);
 	return ret;
 }
+
+void bd_unregister_all_holders(struct gendisk *disk)
+{
+	struct bd_holder_disk *holder;
+
+	mutex_lock(&disk->open_mutex);
+	list_for_each_entry(holder, &disk->slave_bdevs, list)
+		__unlink_disk_holder(holder->bdev, disk);
+	mutex_unlock(&disk->open_mutex);
+}
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 50e358a19d986..ccab9a2dae4bd 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -840,6 +840,7 @@ void set_capacity(struct gendisk *disk, sector_t size);
 int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk);
 void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk);
 int bd_register_pending_holders(struct gendisk *disk);
+void bd_unregister_all_holders(struct gendisk *disk);
 #else
 static inline int bd_link_disk_holder(struct block_device *bdev,
 				      struct gendisk *disk)
@@ -854,6 +855,9 @@ static inline int bd_register_pending_holders(struct gendisk *disk)
 {
 	return 0;
 }
+static inline void bd_unregister_all_holders(struct gendisk *disk)
+{
+}
 #endif /* CONFIG_BLOCK_HOLDER_DEPRECATED */
 
 dev_t part_devt(struct gendisk *disk, u8 partno);
-- 
2.30.2