[PATCHSET] Cleanup io_uring sqe handling

[Jens Axboe <axboe@kernel.dk>]

This series contains some prep work, then two patches that once and for
all cleanup the sqe handling. After this patchset, the prep and issue
handling is fully split, so each opcode has a prep handler that is called
in the same way, and an issue handler that doesn't call the prep handler.

The sqe pointer is removed from io_kiocb, so there cannot be any
accidental dereference after we've done prep. Prep is always done in the
original context, so we can have no reuse issues either.

I've rebased for-5.6/io_uring to have this series first, so this series
applies on top of io_uring-5.5. Ideally we'd put this into 5.5, but...

In any case, please take a look, I think this is a massive improvement
in terms of verifying that we're doing the right thing.

 fs/io_uring.c | 690 ++++++++++++++++++++++++++------------------------
 1 file changed, 355 insertions(+), 335 deletions(-)

-- 
Jens Axboe