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From:   Keith Busch <kbusch@kernel.org>
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On Wed, Mar 20, 2019 at 06:30:29PM +0200, Maxim Levitsky wrote:
> Or instead I can use the block backend, 
> (but note that currently the block back-end doesn't support polling which is
> critical for the performance).

Oh, I think you can do polling through there. For reference, fs/io_uring.c
has a pretty good implementation that aligns with how you could use it.