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.