btrfs: rename __btrfs_map_block to btrfs_map_block

Now that the old btrfs_map_block is gone, drop the leading underscores
from __btrfs_map_block.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 481f3ac..c70805c 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -585,11 +585,11 @@ void btrfs_put_bioc(struct btrfs_io_context *bioc);
 int btrfs_map_sblock(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
 		     u64 logical, u64 *length,
 		     struct btrfs_io_context **bioc_ret);
-int __btrfs_map_block(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
-		      u64 logical, u64 *length,
-		      struct btrfs_io_context **bioc_ret,
-		      struct btrfs_io_stripe *smap, int *mirror_num_ret,
-		      int need_raid_map);
+int btrfs_map_block(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
+		    u64 logical, u64 *length,
+		    struct btrfs_io_context **bioc_ret,
+		    struct btrfs_io_stripe *smap, int *mirror_num_ret,
+		    int need_raid_map);
 int btrfs_map_repair_block(struct btrfs_fs_info *fs_info,
 			   struct btrfs_io_stripe *smap, u64 logical,
 			   u32 length, int mirror_num);