It doesn't really add extra bytes - it "remembers" the original size of the file. So if you update the file to be larger, you only get the first N bytes. If yo

It doesn't really add extra bytes - it "remembers" the original size of the file. So if you update the file to be larger, you only get the first N bytes. If you update it to be smaller, you get the full file + zero bytes at the end to fill out the remainder. If you can't turn off sendfile for some reason, the workaround is to delete the file every time before saving it.