package restorer import ( "os" "golang.org/x/sys/unix" ) func preallocateFile(wr *os.File, size int64) error { if size <= 0 { return nil } // int fallocate(int fd, int mode, off_t offset, off_t len) // use mode = 0 to also change the file size return unix.Fallocate(int(wr.Fd()), 0, 0, size) }