[v4,00/11] dm: Improve zoned block device support

Message

Damien Le Moal May 25, 2021, 2:25 a.m. UTC

This series improve device mapper support for zoned block devices and
of targets exposing a zoned device.

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 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               | 202 +++--------
 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, 955 insertions(+), 207 deletions(-)
 create mode 100644 drivers/md/dm-zone.c