Re: [PATCH v3 4/4] io_uring: add support for zone-append

[Christoph Hellwig]

On Fri, Jul 10, 2020 at 12:35:43AM +0530, Kanchan Joshi wrote:
> Append required special treatment (conversion for sector to bytes) for io_uring.
> And we were planning a user-space wrapper to abstract that.
> 
> But good part (as it seems now) was: append result went along with cflags at
> virtually no additional cost. And uring code changes became super clean/minimal
> with further revisions.
> While indirect-offset requires doing allocation/mgmt in application,
> io-uring submission
> and in completion path (which seems trickier), and those CQE flags
> still get written
> user-space and serve no purpose for append-write.

I have to say that storing the results in the CQE generally make
so much more sense.  I wonder if we need a per-fd "large CGE" flag
that adds two extra u64s to the CQE, and some ops just require this
version.