[PATCH v4 00/12] add large CQE support for io-uring

[Stefan Roesch <shr@fb.com>]

This adds the large CQE support for io-uring. Large CQE's are 16 bytes longer.
To support the longer CQE's the allocation part is changed and when the CQE is
accessed.

The allocation of the large CQE's is twice as big, so the allocation size is
doubled. The ring size calculation needs to take this into account.

All accesses to the large CQE's need to be shifted by 1 to take the bigger size
of each CQE into account. The existing index manipulation does not need to be
changed and can stay the same.

The setup and the completion processing needs to take the new fields into
account and initialize them. For the completion processing these fields need
to be passed through.

The flush completion processing needs to fill the additional CQE32 fields.

The code for overflows needs to be adapted accordingly: the allocation needs to
take large CQE's into account. This means that the order of the fields in the io
overflow structure needs to be changed and the allocation needs to be enlarged
for big CQE's.
In addition the two new fields need to be copied for large CQE's.

The new fields are added to the tracing statements, so the extra1 and extra2
fields are exposed in tracing. The new fields are also exposed in the /proc
filesystem entry.

For testing purposes the extra1 and extra2 fields are used by the nop operation.


Testing:

The exisiting tests have been run with the following configurations and they all
pass:

- Default config
- Large SQE
- Large CQE
- Large SQE and large CQE.

In addition a new test has been added to liburing to verify that extra1 and extra2
are set as expected for the nop operation.

Note:
To use this patch also the corresponding changes to the client library
liburing are required. A different patch series is sent out for this.


Changes:
  V2: - added support for CQE32 in the /proc filesystem entry output function
      - the definition of the io_uring_cqe_extra field has been changed
        to avoid warning with the /proc changes.
  V3: - use __64 for big cqe in io_uring_cqe data structure
      - use io_req_complete_state helper in __io_req_complete32
      - support cached cqe's
      - use bool for cqe32 check in io_cqring_event_overflow
      - use bool for cqe32 check in __io_uring_show_fdinfo
  V4: - Rewording of 2 commit messages


Stefan Roesch (12):
  io_uring: support CQE32 in io_uring_cqe
  io_uring: store add. return values for CQE32
  io_uring: change ring size calculation for CQE32
  io_uring: add CQE32 setup processing
  io_uring: add CQE32 completion processing
  io_uring: modify io_get_cqe for CQE32
  io_uring: flush completions for CQE32
  io_uring: overflow processing for CQE32
  io_uring: add tracing for additional CQE32 fields
  io_uring: support CQE32 in /proc info
  io_uring: enable CQE32
  io_uring: support CQE32 for nop operation

 fs/io_uring.c                   | 234 ++++++++++++++++++++++++++++----
 include/trace/events/io_uring.h |  18 ++-
 include/uapi/linux/io_uring.h   |   7 +
 3 files changed, 225 insertions(+), 34 deletions(-)


base-commit: fd1cf8f1947eb7b009eb79807ec8af0e920fc57b
-- 
2.30.2