[0/7] Improve I/O priority handling

Message

Damien Le Moal Nov. 19, 2018, 3:51 a.m. UTC

This small series based on for-4.21/block brings improvements to I/O priority
hanlding. The main fixes are in patches 5, 6 and 7. These fix BIO and request
I/O priority initialization for both the synchronous and asynchronous pathes.

Of note is that patch 3 is what I beleive a clear bug fix but can result in
userland applications behavior change since a different I/O priority values
will be returned for processes that have *not* executed ioprio_set(). This
needs careful review.

Damien Le Moal (7):
  aio: Comment use of IOCB_FLAG_IOPRIO aio flag
  block: Remove bio->bi_ioc
  block: Fix get_task_ioprio() default return value
  block: Introduce get_current_ioprio()
  aio: Fix fallback I/O priority value
  block: prevent merging of requests with different priorities
  block: Initialize BIO I/O priority early

 block/bio.c                  |  4 ----
 block/blk-core.c             | 12 +-----------
 block/blk-merge.c            | 14 ++++++++++++--
 block/blk-mq-sched.c         |  4 ++--
 block/blk-mq-sched.h         |  2 +-
 block/blk-mq.c               |  4 ++--
 block/blk.h                  | 16 ----------------
 block/ioprio.c               |  2 +-
 fs/aio.c                     |  2 +-
 include/linux/blk_types.h    |  3 +--
 include/linux/fs.h           |  2 +-
 include/linux/ioprio.h       | 13 +++++++++++++
 include/uapi/linux/aio_abi.h |  2 ++
 13 files changed, 37 insertions(+), 43 deletions(-)