Joerg Sonnenberger wrote:
>> I'd say the problem is even worse for partially mapped pages in the middle 
>> of a file.  I.e. map 10 bytes of a 100k file, write to byte 11.
> 
> In that case the fragment will be expanded to a full block on write
> back.

Yes, and the "overflown" buffer will be written to disk.  I'm just pointing out that this "problem" is not limited to "writing behind the file end", but in general "writing behind the map end".

cheers
  simon