fio: current verify status

Hi Shawn/list

I cleaned up and committed some verify changes today, basically:

- Renamed header_offset and header_interval options to verify_offset and
  verify_interval instead. I think it better represents what the options
  do.

- Added verify_pattern option. I hope this does what you want, if not
  then feel free to modify it!

- Split the checksum data from the verify header. For some of the
  smaller checksums, we "waste" too much of the data block size because
  the verify_header encompasses everything from crc7 to sha512.

- Moved the crc stuff to crc/

I'm done with the cleanups I wanted to do, so I wont step on your code
anymore for the time being! So from your list, what is still pending is:

- Verify without IO log. This will be very nice, looking forward to
  that. I'm assuming this also means that you can run a read verify of a
  file without knowing the block sizes from when it was written? That
  would be useful. I'm assuming that is has to handle that, otherwise I
  don't see how verify without an IO log and bsrange= would work.

- The extra signature containing info about the block written. Also a
  very useful addition, I think.

So I hope you'll proceeded and get those in. Thanks!

-- 
Jens Axboe