Merge branch 'loop-aio-nowait' into for-6.19/block

Merge async IO IOCB_NOWAIT support from Ming:

"This patchset improves loop aio perf by using IOCB_NOWAIT for avoiding
 to queue aio command to workqueue context, meantime refactor
 lo_rw_aio() a bit.

 In my test VM, loop disk perf becomes very close to perf of the backing
 block device(nvme/mq virtio-scsi).

 And Mikulas verified that this way can improve 12jobs sequential
 readwrite io by ~5X, and basically solve the reported problem together
 with loop MQ change.

 https://lore.kernel.org/linux-block/a8e5c76a-231f-07d1-a394-847de930f638@redhat.com/

 Zhaoyang Huang also mentioned it may fix their performance issue on
 Android use case.

 The loop MQ change will be posted as standalone patch, because it needs
 UAPI change."

Link: https://lore.kernel.org/linux-block/20251015110735.1361261-1-ming.lei@redhat.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
* loop-aio-nowait:
  loop: add hint for handling aio via IOCB_NOWAIT
  loop: try to handle loop aio command via NOWAIT IO first
  loop: move command blkcg/memcg initialization into loop_queue_work
  loop: add lo_submit_rw_aio()
  loop: add helper lo_rw_aio_prep()
  loop: add helper lo_cmd_nr_bvec()