block: merge disk_scan_partitions and blkdev_reread_part

Unify the functionality that implements a partition rescan for a
gendisk.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-6-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/blk.h

@@ -449,6 +449,7 @@ int bio_add_hw_page(struct request_queue *q, struct bio *bio,
 		unsigned int max_sectors, bool *same_page);
 
 struct request_queue *blk_alloc_queue(int node_id);
+int disk_scan_partitions(struct gendisk *disk, fmode_t mode);
 
 int disk_alloc_events(struct gendisk *disk);
 void disk_add_events(struct gendisk *disk);

block/genhd.c

@@ -372,17 +372,21 @@ void disk_uevent(struct gendisk *disk, enum kobject_action action)
 }
 EXPORT_SYMBOL_GPL(disk_uevent);
 
-static void disk_scan_partitions(struct gendisk *disk)
+int disk_scan_partitions(struct gendisk *disk, fmode_t mode)
 {
 	struct block_device *bdev;
 
-	if (!get_capacity(disk) || !disk_part_scan_enabled(disk))
-		return;
+	if (!disk_part_scan_enabled(disk))
+		return -EINVAL;
+	if (disk->open_partitions)
+		return -EBUSY;
 
 	set_bit(GD_NEED_PART_SCAN, &disk->state);
-	bdev = blkdev_get_by_dev(disk_devt(disk), FMODE_READ, NULL);
-	if (!IS_ERR(bdev))
-		blkdev_put(bdev, FMODE_READ);
+	bdev = blkdev_get_by_dev(disk_devt(disk), mode, NULL);
+	if (IS_ERR(bdev))
+		return PTR_ERR(bdev);
+	blkdev_put(bdev, mode);
+	return 0;
 }
 
 /**
@@ -509,7 +513,8 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
 			goto out_unregister_bdi;
 
 		bdev_add(disk->part0, ddev->devt);
-		disk_scan_partitions(disk);
+		if (get_capacity(disk))
+			disk_scan_partitions(disk, FMODE_READ);
 
 		/*
 		 * Announce the disk and partitions after all partitions are

block/ioctl.c

@@ -82,31 +82,6 @@ static int compat_blkpg_ioctl(struct block_device *bdev,
 }
 #endif
 
-static int blkdev_reread_part(struct block_device *bdev, fmode_t mode)
-{
-	struct block_device *tmp;
-
-	if (!disk_part_scan_enabled(bdev->bd_disk) || bdev_is_partition(bdev))
-		return -EINVAL;
-	if (!capable(CAP_SYS_ADMIN))
-		return -EACCES;
-	if (bdev->bd_disk->open_partitions)
-		return -EBUSY;
-
-	/*
-	 * Reopen the device to revalidate the driver state and force a
-	 * partition rescan.
-	 */
-	mode &= ~FMODE_EXCL;
-	set_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
-
-	tmp = blkdev_get_by_dev(bdev->bd_dev, mode, NULL);
-	if (IS_ERR(tmp))
-		return PTR_ERR(tmp);
-	blkdev_put(tmp, mode);
-	return 0;
-}
-
 static int blk_ioctl_discard(struct block_device *bdev, fmode_t mode,
 		unsigned long arg, unsigned long flags)
 {
@@ -522,7 +497,11 @@ static int blkdev_common_ioctl(struct block_device *bdev, fmode_t mode,
 		bdev->bd_disk->bdi->ra_pages = (arg * 512) / PAGE_SIZE;
 		return 0;
 	case BLKRRPART:
-		return blkdev_reread_part(bdev, mode);
+		if (!capable(CAP_SYS_ADMIN))
+			return -EACCES;
+		if (bdev_is_partition(bdev))
+			return -EINVAL;
+		return disk_scan_partitions(bdev->bd_disk, mode & ~FMODE_EXCL);
 	case BLKTRACESTART:
 	case BLKTRACESTOP:
 	case BLKTRACETEARDOWN: