Adds check for numberio during verify phase.

Currently, fio checks the block offset number in a block's header during
the verify phase.
We add a check for the io number (numberio) to detect stale blocks. This
check is performed only on workloads that write data, as those workloads
know what numberio was written to each block.
td->io_issues[ddir] = 0; was removed so that numberio does not get reset
at each iteration; we want numberio to keep incrementing to reflect
how many times the same data was written.

Signed-off-by: Juan Casse <jcasse@chromium.org>
Reviewed-by: Grant Grundler <grundler@chromium.org>

Fixed typo.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Adds verify_only option

When this option is set, a dry run (no actual io is performed) of the
workload will be done in order to compute the numberio for each block
header without overwriting the data on disk. Then, do_verify() will be
effectively verifying data that was written in a previous fio run.
In the case that "loops" is set to more than 1, do_verify() will delay
the verification of numberio to the last iteration when the same
numberio state that would have been written to disk in a previous
fio run has been reached.

Signed-off-by: Juan Casse <jcasse@chromium.org>
Reviewed-by: Grant Grundler <grundler@chromium.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Adds check for rand_seed during verify phase.

Improve data integrity checking of header (meta) data.
verify_header() will now return an additional error:
"verify: bad header rand seed ..."
The addition of the check of rand_seed helps detect stale data from
previous fio runs.
This patch also disambiguates the different data mismatches by returning
different error codes from verify_header().

Signed-off-by: Juan Casse <jcasse@chromium.org>
Reviewed-by: Grant Grundler <grundler@chromium.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add verify_only to man page

Signed-off-by: Jens Axboe <axboe@kernel.dk>