u64 alloc_hint = 0;
        u64 num_bytes;
        unsigned long ram_size;
-       u64 disk_num_bytes;
        u64 cur_alloc_size = 0;
        u64 blocksize = fs_info->sectorsize;
        struct btrfs_key ins;
 
        num_bytes = ALIGN(end - start + 1, blocksize);
        num_bytes = max(blocksize,  num_bytes);
-       disk_num_bytes = num_bytes;
 
        inode_should_defrag(BTRFS_I(inode), start, end, num_bytes, SZ_64K);
 
                }
        }
 
-       BUG_ON(disk_num_bytes >
-              btrfs_super_total_bytes(fs_info->super_copy));
+       BUG_ON(num_bytes > btrfs_super_total_bytes(fs_info->super_copy));
 
        alloc_hint = get_extent_allocation_hint(inode, start, num_bytes);
        btrfs_drop_extent_cache(BTRFS_I(inode), start,
                        start + num_bytes - 1, 0);
 
-       while (disk_num_bytes > 0) {
-               cur_alloc_size = disk_num_bytes;
+       while (num_bytes > 0) {
+               cur_alloc_size = num_bytes;
                ret = btrfs_reserve_extent(root, cur_alloc_size, cur_alloc_size,
                                           fs_info->sectorsize, 0, alloc_hint,
                                           &ins, 1, 1);
                                             delalloc_end, locked_page,
                                             EXTENT_LOCKED | EXTENT_DELALLOC,
                                             page_ops);
-               if (disk_num_bytes < cur_alloc_size)
-                       disk_num_bytes = 0;
+               if (num_bytes < cur_alloc_size)
+                       num_bytes = 0;
                else
-                       disk_num_bytes -= cur_alloc_size;
-               num_bytes -= cur_alloc_size;
+                       num_bytes -= cur_alloc_size;
                alloc_hint = ins.objectid + ins.offset;
                start += cur_alloc_size;
                extent_reserved = false;