block: refactor blk_drop_partitions

Move the busy check and disk-wide sync into the only caller, so that
the remainder can be shared with del_gendisk.  Also pass the gendisk
instead of the bdev as that is all that is needed.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210406062303.811835-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk.h

@@ -349,7 +349,6 @@ char *disk_name(struct gendisk *hd, int partno, char *buf);
 #define ADDPART_FLAG_NONE	0
 #define ADDPART_FLAG_RAID	1
 #define ADDPART_FLAG_WHOLEDISK	2
-void delete_partition(struct block_device *part);
 int bdev_add_partition(struct block_device *bdev, int partno,
 		sector_t start, sector_t length);
 int bdev_del_partition(struct block_device *bdev, int partno);

block/genhd.c

@@ -667,9 +667,6 @@ EXPORT_SYMBOL(device_add_disk_no_queue_reg);
  */
 void del_gendisk(struct gendisk *disk)
 {
-	struct disk_part_iter piter;
-	struct block_device *part;
-
 	might_sleep();
 
 	if (WARN_ON_ONCE(!disk->queue))
@@ -683,13 +680,7 @@ void del_gendisk(struct gendisk *disk)
 	 * disk is marked as dead (GENHD_FL_UP cleared).
 	 */
 	down_write(&bdev_lookup_sem);
-
-	/* invalidate stuff */
-	disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
-	while ((part = disk_part_iter_next(&piter)))
-		delete_partition(part);
-	disk_part_iter_exit(&piter);
-
+	blk_drop_partitions(disk);
 	fsync_bdev(disk->part0);
 	__invalidate_device(disk->part0, true);
 

block/partitions/core.c

@@ -285,7 +285,7 @@ struct device_type part_type = {
  * Must be called either with bd_mutex held, before a disk can be opened or
  * after all disk users are gone.
  */
-void delete_partition(struct block_device *part)
+static void delete_partition(struct block_device *part)
 {
 	fsync_bdev(part);
 	__invalidate_device(part, true);
@@ -526,23 +526,15 @@ static bool disk_unlock_native_capacity(struct gendisk *disk)
 	}
 }
 
-int blk_drop_partitions(struct block_device *bdev)
+void blk_drop_partitions(struct gendisk *disk)
 {
 	struct disk_part_iter piter;
 	struct block_device *part;
 
-	if (bdev->bd_part_count)
-		return -EBUSY;
-
-	sync_blockdev(bdev);
-	invalidate_bdev(bdev);
-
-	disk_part_iter_init(&piter, bdev->bd_disk, DISK_PITER_INCL_EMPTY);
+	disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
 	while ((part = disk_part_iter_next(&piter)))
 		delete_partition(part);
 	disk_part_iter_exit(&piter);
-
-	return 0;
 }
 
 static bool blk_add_partition(struct gendisk *disk, struct block_device *bdev,

fs/block_dev.c

@@ -1243,9 +1243,11 @@ int bdev_disk_changed(struct block_device *bdev, bool invalidate)
 	clear_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
 
 rescan:
-	ret = blk_drop_partitions(bdev);
-	if (ret)
-		return ret;
+	if (bdev->bd_part_count)
+		return -EBUSY;
+	sync_blockdev(bdev);
+	invalidate_bdev(bdev);
+	blk_drop_partitions(disk);
 
 	/*
 	 * Historically we only set the capacity to zero for devices that

include/linux/genhd.h

@@ -273,7 +273,7 @@ static inline sector_t get_capacity(struct gendisk *disk)
 
 int bdev_disk_changed(struct block_device *bdev, bool invalidate);
 int blk_add_partitions(struct gendisk *disk, struct block_device *bdev);
-int blk_drop_partitions(struct block_device *bdev);
+void blk_drop_partitions(struct gendisk *disk);
 
 extern struct gendisk *__alloc_disk_node(int minors, int node_id);
 extern void put_disk(struct gendisk *disk);