block: cleanup partition scanning in register_disk

Use blkdev_get_by_dev instead of open coding it using bdget_disk +
blkdev_get, and split the code to read the partition table into a
separate helper to make it a little more obvious.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/genhd.c b/block/genhd.c
index 7b56203..05fb27c 100644 (file)
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -673,11 +673,23 @@ static int exact_lock(dev_t devt, void *data)
        return 0;
 }
 
+static void disk_scan_partitions(struct gendisk *disk)
+{
+       struct block_device *bdev;
+
+       if (!get_capacity(disk) || !disk_part_scan_enabled(disk))
+               return;
+
+       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);
+}
+
 static void register_disk(struct device *parent, struct gendisk *disk,
                          const struct attribute_group **groups)
 {
        struct device *ddev = disk_to_dev(disk);
-       struct block_device *bdev;
        struct disk_part_iter piter;
        struct hd_struct *part;
        int err;
@@ -719,25 +731,8 @@ static void register_disk(struct device *parent, struct gendisk *disk,
                return;
        }
 
-       /* No minors to use for partitions */
-       if (!disk_part_scan_enabled(disk))
-               goto exit;
-
-       /* No such device (e.g., media were just removed) */
-       if (!get_capacity(disk))
-               goto exit;
-
-       bdev = bdget_disk(disk, 0);
-       if (!bdev)
-               goto exit;
-
-       set_bit(GD_NEED_PART_SCAN, &disk->state);
-       err = blkdev_get(bdev, FMODE_READ, NULL);
-       if (err < 0)
-               goto exit;
-       blkdev_put(bdev, FMODE_READ);
+       disk_scan_partitions(disk);
 
-exit:
        /* announce disk after possible partitions are created */
        dev_set_uevent_suppress(ddev, 0);
        kobject_uevent(&ddev->kobj, KOBJ_ADD);