Re: [dm-devel] [PATCH v5 00/11] dm: Improve zoned block device support

[Damien Le Moal <Damien.LeMoal@wdc.com>]

On 2021/05/26 6:25, Damien Le Moal wrote:
> This series improve device mapper support for zoned block devices and
> of targets exposing a zoned device.

Mike, Jens,

Any feedback regarding this series ?

> 
> The first patch improve support for user requests to reset all zones of
> the target device. With the fix, such operation behave similarly to
> physical block devices implementation based on the single zone reset
> command with the ALL bit set.
> 
> The following 2 patches are preparatory block layer patches.
> 
> Patch 4 and 5 are 2 small fixes to DM core zoned block device support.
> 
> Patch 6 reorganizes DM core code, moving conditionally defined zoned
> block device code into the new dm-zone.c file. This avoids sprinkly DM
> with zone related code defined under an #ifdef CONFIG_BLK_DEV_ZONED.
> 
> Patch 7 improves DM zone report helper functions for target drivers.
> 
> Patch 8 fixes a potential problem with BIO requeue on zoned target.
> 
> Finally, patch 9 to 11 implement zone append emulation using regular
> writes for target drivers that cannot natively support this BIO type.
> The only target currently needing this emulation is dm-crypt. With this
> change, a zoned dm-crypt device behaves exactly like a regular zoned
> block device, correctly executing user zone append BIOs.
> 
> This series passes the following tests:
> 1) zonefs tests on top of dm-crypt with a zoned nullblk device
> 2) zonefs tests on top of dm-crypt+dm-linear with an SMR HDD
> 3) btrfs fstests on top of dm-crypt with zoned nullblk devices.
> 
> Comments are as always welcome.
> 
> Changes from v4:
> * Remove useless extra space in variable initialization in patch 1
> * Shorten dm_accept_partial_bio() documentation comment in patch 4
> * Added reviewed-by tags
> 
> Changes from v3:
> * Fixed missing variable initialization in
>   blkdev_zone_reset_all_emulated() in patch 1.
> * Rebased on rc3
> * Added reviewed-by tags
> 
> Changes from v2:
> * Replace use of spinlock to protect the zone write pointer offset
>   array in patch 11 with READ_ONCE/WRITE_ONCE as suggested by Hannes.
> * Added reviewed-by tags
> 
> Changes from v1:
> * Use Christoph proposed approach for patch 1 (split reset all
>   processing into different functions)
> * Changed helpers introduced in patch 2 to remove the request_queue
>   argument
> * Improve patch 3 commit message as suggested by Christoph (explaining
>   that the flag is a special case that cannot use a REQ_XXX flag)
> * Changed DMWARN() into DMDEBUG in patch 11 as suggested by Milan
> * Added reviewed-by tags
> 
> Damien Le Moal (11):
>   block: improve handling of all zones reset operation
>   block: introduce bio zone helpers
>   block: introduce BIO_ZONE_WRITE_LOCKED bio flag
>   dm: Fix dm_accept_partial_bio()
>   dm: cleanup device_area_is_invalid()
>   dm: move zone related code to dm-zone.c
>   dm: Introduce dm_report_zones()
>   dm: Forbid requeue of writes to zones
>   dm: rearrange core declarations
>   dm: introduce zone append emulation
>   dm crypt: Fix zoned block device support
> 
>  block/blk-zoned.c             | 119 +++++--
>  drivers/md/Makefile           |   4 +
>  drivers/md/dm-core.h          |  65 ++++
>  drivers/md/dm-crypt.c         |  31 +-
>  drivers/md/dm-flakey.c        |   7 +-
>  drivers/md/dm-linear.c        |   7 +-
>  drivers/md/dm-table.c         |  21 +-
>  drivers/md/dm-zone.c          | 654 ++++++++++++++++++++++++++++++++++
>  drivers/md/dm.c               | 201 +++--------
>  drivers/md/dm.h               |  30 +-
>  include/linux/blk_types.h     |   1 +
>  include/linux/blkdev.h        |  12 +
>  include/linux/device-mapper.h |   9 +-
>  13 files changed, 954 insertions(+), 207 deletions(-)
>  create mode 100644 drivers/md/dm-zone.c
> 


-- 
Damien Le Moal
Western Digital Research



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