Messages in this thread | | | From | Zach Brown <> | Subject | Re: [PATCH 2/2] aio: propogate post-EIOCBQUEUED errors to completion event | Date | Wed, 21 Feb 2007 10:34:28 -0800 |
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> This is an interesting trick, but I'd like to consider hard whether > the added > complexity is worth it. Could you list the various other cases you > have in mind > which would want to use it ?
I'm happy to report that the sync case and the invalidate_inode_pages2_range() case are the only two which try to rewrite 'ret'. I audited all the call paths between aio_{read,write} and -EIOCBQUUEUED.
So, sure, maybe we can shuffle the house of cards a little in the direction away from having a fs/aio.c helper for the situation by simply removing the few current instances of the problem. It won't scale as people add problems without knowing about the rule to not overwrite -EIOCBQUEUED, but hopefully that won't be a rule for much longer :) :).
For the O_SYNC case we could add another magical test to the is_async assignment which won't perform AIO on O_SYNC descriptors.
> For the invalidate_inode_pages2_range() case, I wonder if the right > place to issue this is after the direct IO write has completed and > before > aio_complete() is issued (somewhat like the way we do > bio_check_pages_dirty > for DIO reads), rather than after submission when the IO may still > not have > hit the disk. This would also make the behaviour uniform for > synchronous and > async cases.
Hmm, I think I like that. It solves the problem for the current sole user of -EIOCBQUEUED without too much disruption.
> BTW, am I right in interpreting that with your change aio_complete > () may > trigger an io_getevents() wakeup, before the corresponding event is > placed > on the ring buffer ?
Hmm, yeah, it looks like I goofed that.
I'll roll a patch which does the invalidation down in fs/direct-io.c.
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