* return 0 on success, otherwise return error
  */
 static int __do_readpage(struct page *page, struct extent_map **em_cached,
-                        struct bio **bio, int mirror_num,
-                        unsigned long *bio_flags, unsigned int read_flags,
-                        u64 *prev_em_start)
+                        struct bio **bio, unsigned long *bio_flags,
+                        unsigned int read_flags, u64 *prev_em_start)
 {
        struct inode *inode = page->mapping->host;
        u64 start = page_offset(page);
                ret = submit_extent_page(REQ_OP_READ | read_flags, NULL,
                                         page, offset, disk_io_size,
                                         pg_offset, bio,
-                                        end_bio_extent_readpage, mirror_num,
+                                        end_bio_extent_readpage, 0,
                                         *bio_flags,
                                         this_bio_flag,
                                         force_bio_submit);
        btrfs_lock_and_flush_ordered_range(inode, start, end, NULL);
 
        for (index = 0; index < nr_pages; index++) {
-               __do_readpage(pages[index], em_cached, bio, 0, bio_flags,
+               __do_readpage(pages[index], em_cached, bio, bio_flags,
                              REQ_RAHEAD, prev_em_start);
                put_page(pages[index]);
        }
 
        btrfs_lock_and_flush_ordered_range(inode, start, end, NULL);
 
-       ret = __do_readpage(page, NULL, bio, 0, bio_flags, 0, NULL);
+       ret = __do_readpage(page, NULL, bio, bio_flags, 0, NULL);
        return ret;
 }