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[V2,00/13] block: don't drain file system I/O on del_gendisk

Message ID 20220122111054.1126146-1-ming.lei@redhat.com
Headers show
Series block: don't drain file system I/O on del_gendisk | expand

Message

Ming Lei Jan. 22, 2022, 11:10 a.m. UTC 
Hello,

Draining FS I/O on del_gendisk() is added for just avoiding to refer to
recently added q->disk in IO path, and it isn't actually reliable:

1) queue freezing can't drain FS I/O for bio based driver, so blk-cgroup
shutdown can't be moved into del_gendisk()

2) freezing queue can't drain in-progress IO issue/dispatch activities,
so elevator shutdown can't be moved into del_gendisk()

3) the added flag of GD_DEAD may not be observed reliably in
__bio_queue_enter() because queue freezing might not imply rcu grace
period.

4) passthrough IO accounting code can refer to q->disk after disk is
released

When releasing disk, all FS IOs are guaranteed to be done, so this
patchset tries to shutdown elevator/blk-cgroup/rq qos there, then
referring to q->disk can be avoided after disk is released.

Also add flag of BLK_MQ_REQ_USER_IO for accounting passthrough IO
only if the IO is from userspace, since disk is live for user
passthrough IO.

V2:
	- take new approach to make current referring to q->disk reliable


Laibin Qiu (1):
  block/wbt: fix negative inflight counter when remove scsi device

Ming Lei (12):
  block: declare blkcg_[init|exit]_queue in private header
  block: move initialization of q->blkg_list into blkcg_init_queue
  block: move blkcg initialization/destroy into disk allocation/release
    handler
  block: only account passthrough IO from userspace
  block: don't remove hctx debugfs dir from blk_mq_exit_queue
  block: move q_usage_counter release into blk_queue_release
  block: export __blk_mq_unfreeze_queue
  scsi: force unfreezing queue into atomic mode
  block: add helper of disk_release_queue for release queue data for
    disk
  block: move blk_exit_queue into disk_release
  block: move rq_qos_exit() into disk_release()
  block: don't drain file system I/O on del_gendisk

 block/bfq-iosched.c        |  2 +
 block/blk-cgroup.c         |  2 +
 block/blk-core.c           | 31 ++++----------
 block/blk-mq.c             | 27 ++++++++++--
 block/blk-sysfs.c          | 25 +-----------
 block/blk.h                | 10 ++++-
 block/elevator.c           |  2 -
 block/genhd.c              | 84 +++++++++++++++++++++++++++-----------
 drivers/nvme/host/ioctl.c  |  2 +-
 drivers/scsi/scsi_ioctl.c  |  3 +-
 drivers/scsi/sd.c          |  2 +-
 include/linux/blk-cgroup.h |  4 --
 include/linux/blk-mq.h     |  3 ++
 include/linux/genhd.h      |  1 -
 14 files changed, 114 insertions(+), 84 deletions(-)