On Wed, Sep 14, 2011 at 04:50:25PM +0100, Stefan Hajnoczi wrote: > I think in this case it will not make the code nicer. Since the > external iSCSI library is based on callbacks it would be necessary to > write the coroutines<->callbacks adapter functions. So for example, > the READ10 command would need a function that can be called in > coroutine context and yields while libiscsi does the I/O. When the > callback is invoked it will re-enter the coroutine. > > The area where coroutines are useful in the block layer is for image > formats. We already have common coroutines<->callback adapter > functions in block.c so it's possible to write sequential code for > image formats. They only need access to block layer functions which > have already been adapted. But as soon as you interact with a > callback-based API from the coroutine, then you need to write an > adapter yourself.
So you plan on keeping the aio interface around forever? Qemu with two different I/O pathes was already more than painful enough, I don't think keeping three, and two of them beeing fairly complex is a good idea.
