block: merge struct block_device and struct hd_struct

Instead of having two structures that represent each block device with
different life time rules, merge them into a single one.  This also
greatly simplifies the reference counting rules, as we can use the inode
reference count as the main reference count for the new struct
block_device, with the device model reference front ending it for device
model interaction.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

3 files changed, 15 insertions, 34 deletions

diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 6edea5c16259..866f74261b3b 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -8,6 +8,7 @@
 
 #include <linux/types.h>
 #include <linux/bvec.h>
+#include <linux/device.h>
 #include <linux/ktime.h>
 
 struct bio_set;
@@ -30,6 +31,7 @@ struct block_device {
 	struct super_block *	bd_super;
 	struct mutex		bd_mutex;	/* open/close mutex */
 	void *			bd_claiming;
+	struct device		bd_device;
 	void *			bd_holder;
 	int			bd_holders;
 	bool			bd_write_holder;
@@ -38,7 +40,6 @@ struct block_device {
 #endif
 	struct kobject		*bd_holder_dir;
 	u8			bd_partno;
-	struct hd_struct *	bd_part;
 	/* number of times partitions within this device have been opened. */
 	unsigned		bd_part_count;
 
@@ -61,8 +62,11 @@ struct block_device {
 #define bdev_whole(_bdev) \
 	((_bdev)->bd_disk->part0)
 
+#define dev_to_bdev(device) \
+	container_of((device), struct block_device, bd_device)
+
 #define bdev_kobj(_bdev) \
-	(&part_to_dev((_bdev)->bd_part)->kobj)
+	(&((_bdev)->bd_device.kobj))
 
 /*
  * Block error status values.  See block/blk-core:blk_errors for the details.
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 1d4be1fc6007..17cedf0dc83d 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1999,7 +1999,6 @@ void blkdev_put_no_open(struct block_device *bdev);
 struct block_device *bdev_alloc(struct gendisk *disk, u8 partno);
 void bdev_add(struct block_device *bdev, dev_t dev);
 struct block_device *I_BDEV(struct inode *inode);
-struct block_device *bdget_part(struct hd_struct *part);
 struct block_device *bdgrab(struct block_device *bdev);
 void bdput(struct block_device *);
 
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index cd23c80265b2..809aaa32d53c 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -19,12 +19,6 @@
 #include <linux/blk_types.h>
 #include <asm/local.h>
 
-#define dev_to_part(device)	container_of((device), struct hd_struct, __dev)
-#define part_to_dev(part)	(&((part)->__dev))
-
-#define dev_to_disk(device)	(dev_to_part(device)->bdev->bd_disk)
-#define disk_to_dev(disk)	(part_to_dev((disk)->part0->bd_part))
-
 extern const struct device_type disk_type;
 extern struct device_type part_type;
 extern struct class block_class;
@@ -51,11 +45,6 @@ struct partition_meta_info {
 	u8 volname[PARTITION_META_INFO_VOLNAMELTH];
 };
 
-struct hd_struct {
-	struct block_device *bdev;
-	struct device __dev;
-};
-
 /**
  * DOC: genhd capability flags
  *
@@ -190,19 +179,21 @@ struct gendisk {
 	struct lockdep_map lockdep_map;
 };
 
+/*
+ * The gendisk is refcounted by the part0 block_device, and the bd_device
+ * therein is also used for device model presentation in sysfs.
+ */
+#define dev_to_disk(device) \
+	(dev_to_bdev(device)->bd_disk)
+#define disk_to_dev(disk) \
+	(&((disk)->part0->bd_device))
+
 #if IS_REACHABLE(CONFIG_CDROM)
 #define disk_to_cdi(disk)	((disk)->cdi)
 #else
 #define disk_to_cdi(disk)	NULL
 #endif
 
-static inline struct gendisk *part_to_disk(struct hd_struct *part)
-{
-	if (unlikely(!part))
-		return NULL;
-	return part->bdev->bd_disk;
-}
-
 static inline int disk_max_parts(struct gendisk *disk)
 {
 	if (disk->flags & GENHD_FL_EXT_DEVT)
@@ -221,19 +212,6 @@ static inline dev_t disk_devt(struct gendisk *disk)
 	return MKDEV(disk->major, disk->first_minor);
 }
 
-static inline dev_t part_devt(struct hd_struct *part)
-{
-	return part_to_dev(part)->devt;
-}
-
-extern struct hd_struct *disk_get_part(struct gendisk *disk, int partno);
-
-static inline void disk_put_part(struct hd_struct *part)
-{
-	if (likely(part))
-		put_device(part_to_dev(part));
-}
-
 /*
  * Smarter partition iterator without context limits.
  */