Re: [PATCH v5 0/7] Elevator cleanups and improvements

[Ming Lei <ming.lei@redhat.com>]

On Thu, Sep 05, 2019 at 06:51:28PM +0900, Damien Le Moal wrote:
> This patch series implements some cleanup of the elevator initialization
> code and introduces elevator features identification and device matching
> to enhance checks for elevator/device compatibility and fitness.
> 
> The first 2 patches of the series are simple cleanups which simplify 
> elevator initialization for newly allocated device queues.
> 
> Patch 3 introduce elevator features, allowing a clean and extensible
> definition of devices and features that an elevator supports and match
> these against features required by a block device. With this, the sysfs
> elevator list for a device always shows only elevators matching the
> features that a particular device requires, with the exception of the
> none elevator which has no features but is always available for use
> with any device.
> 
> The first feature defined is for zoned block device sequential write
> constraint support through zone write locking which prevents the use of
> any elevator that does not support this feature with zoned devices.
> 
> The last 4 patches of this series rework the default elevator selection
> and initialization to allow for the elevator/device features matching
> to work, doing so addressing cases not currently well supported, namely,
> multi-queue zoned block devices.
> 
> Changes from v4:
> * Fix patch 5 again to correctly handle request based DM devices and
>   avoid that default queue elevator of these devices end up always
>   being "none".
> 
> Changes from v3:
> * Fixed patch 5 to correctly handle DM devices which do not register a
>   request queue and so do not need elevator initialization.
> 
> Changes from v2:
> * Fixed patch 4
> * Call elevator_init_mq() earlier in device_add_disk() as suggested by
>   Christoph (patch 5)
> * Fixed title of patch 7
> 
> Changes from v1:
> * Addressed Johannes comments
> * Rebased on newest for-next branch to include Ming's sysfs lock changes
> 
> Damien Le Moal (7):
>   block: Cleanup elevator_init_mq() use
>   block: Change elevator_init_mq() to always succeed
>   block: Introduce elevator features
>   block: Improve default elevator selection
>   block: Delay default elevator initialization
>   block: Set ELEVATOR_F_ZBD_SEQ_WRITE for nullblk zoned disks
>   sd: Set ELEVATOR_F_ZBD_SEQ_WRITE for ZBC disks
> 
>  block/blk-mq.c                |  20 +++--
>  block/blk-settings.c          |  16 ++++
>  block/blk.h                   |   2 +-
>  block/elevator.c              | 137 ++++++++++++++++++++++++++--------
>  block/genhd.c                 |   9 +++
>  block/mq-deadline.c           |   1 +
>  drivers/block/null_blk_main.c |   2 +
>  drivers/md/dm-rq.c            |   2 +-
>  drivers/scsi/sd_zbc.c         |   2 +
>  include/linux/blk-mq.h        |   3 +-
>  include/linux/blkdev.h        |   4 +
>  include/linux/elevator.h      |   8 ++
>  12 files changed, 161 insertions(+), 45 deletions(-)

Looks fine for the series:

Reviewed-by: Ming Lei <ming.lei@redhat.com>


Thanks,
Ming