Comment 3 for bug 1891169

I have also observed strange behavior with the fio 3.16 package on Focal. It occurs with the combination of "size" and "offset", and is affected by the presence of "time_based".

For example with this command:

fio --name=test --filename=/dev/loop9 --ioengine=libaio --rw=write --direct=1 --offset=8M --size=8M --time_based --runtime=2

I observe that the device is written from 8M to the end. I have tested with a range of other fio versions and they all write from 8M to 16M as expected.

It looks like the issue was introduced with https://github.com/axboe/fio/commit/ad46c5715ffc5d4e70d2e941225b1f504f23e409
This commit was reverted in https://github.com/axboe/fio/commit/0d0601479d593ca9e96e35f43e2c0586f8358f34
The only fio version containing the original commit but not the revert is 3.16.

I have not experienced this exact failure but it seems very likely to have the same root cause.