btrfs: use raid_attr table for btrfs_bg_type_to_factor

The factor is the number of copies.

Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/volumes.c

@@ -7586,10 +7586,9 @@ void btrfs_reset_fs_info_ptr(struct btrfs_fs_info *fs_info)
  */
 int btrfs_bg_type_to_factor(u64 flags)
 {
-	if (flags & (BTRFS_BLOCK_GROUP_DUP | BTRFS_BLOCK_GROUP_RAID1 |
+	const int index = btrfs_bg_flags_to_raid_index(flags);
-		     BTRFS_BLOCK_GROUP_RAID10))
+
-		return 2;
+	return btrfs_raid_array[index].ncopies;
-	return 1;
 }