Re: [RFC 0/5] dio: clean up completion phase of direct_io_worker()

[Jeff Moyer <jmoyer@redhat.com>]

==> Regarding Re: [RFC 0/5] dio: clean up completion phase of direct_io_worker(); Zach Brown <zach.brown@oracle.com> adds:

>> This all looks good, the code is much easier to follow.  What do you think
>> about making dio->result an unsigned quantity?  It should never be negative
>> now that there is an io_error field.

zach.brown> Yeah, that has always bugged me too.  I considered renaming it
zach.brown> 'issued', or something, as part of this patchset but thought we
zach.brown> could do it later.

I figured since you were doing some house-keeping, we might as well clean
up as much as possible.  It's up to you, though.  ;)

zach.brown> While we're on this topic, I'm nervious that we increment it
zach.brown> when do_direct_IO fails.  It might be sound, but that we
zach.brown> consider it the amount of work "transferred" for dio->end_io
zach.brown> makes me want to make sure there aren't confusing corner cases
zach.brown> here.

It does look non-obvious when reading the code.  However, I'm pretty sure
it's right.  dio->block_in_file is only updated if there is no error
returned from submit_page_section.  As such, it really does reflect how
much work was done before the error, right?  It does seem odd that we do
this math in two separate places, though.

-Jeff