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

[Jeff Moyer]

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

zach.brown> There have been a lot of bugs recently due to the way
zach.brown> direct_io_worker() tries to decide how to finish direct IO
zach.brown> operations.  In the worst examples it has failed to call
zach.brown> aio_complete() at all (hang) or called it too many times
zach.brown> (oops).

zach.brown> This set of patches cleans up the completion phase with the
zach.brown> goal of removing the complexity that lead to these bugs.  We
zach.brown> end up with one path that calculates the result of the
zach.brown> operation after all off the bios have completed.  We decide
zach.brown> when to generate a result of the operation using that path
zach.brown> based on the final release of a refcount on the dio structure.

[...]

zach.brown> I hoped to get some feedback (and maybe volunteers for
zach.brown> testing!) by sending the patches out before waiting for the
zach.brown> stress tests.

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.

ACK.

Jeff
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