[PATCHv8 00/23] ALUA device handler update, part II

[Hannes Reinecke <hare@suse.de>]

As promised here is now the second part of my ALUA device handler update.
This contains a major rework of the ALUA device handler as execution is
moved onto a workqueue. This has the advantage that we avoid having to
do multiple calls to the same LUN (as happens frequently when failing
over a LUN with several paths) and finally retries are handled correctly.
As some arrays are only capable of handling one STPG at a time I've added
a blacklist flag which then uses a singlethreaded workqueue, thereby
effectively synchronize STPG handling.
Thanks to Bart for this suggestion.

The entire patchset can be found at:
git.kernel.org:/hare/scsi-devel/h/alua-2.v8

As usual, comments and reviews are welcome.

Changes to v7:
- Remove SCSI_ACCESS_STATE_UNKNOWN as suggested by Bart
- Fixup typo in pg->flags as suggested by Bart
- Return -EINVAL when reading from access_state and no
  device handler is attached.

Changes to v6:
- Fixup mutex lockdep issue noticed by Bart
- Reshuffle locks in alua_check_vpd

Changes to v5:
- Fixup lock imbalance noticed by Bart
- use #define instead of enum for access_state as suggested by Ewan
- Updated patch description as suggested by Ewan
- Changed occurrences to 'SET TARGET PORT GROUP' as suggested by Bart

Changes to v4:
- use kfree_rcu() as suggested by hch
- Use 'IS_ERR' instead of 'PTR_ERR' when checking for validity
  of a pointer
- Simplify pg assignment as suggested by hch
- Use separate WARN_ON statements a suggested by hch
- Fixes to avoid I/O stall on failover

Changes to v3:
- Use scsi_device flag for blacklisting as suggested by hch
- Add Arrays for synchronous ALUA handling
- Move synchronize_rcu() into release_port_group()
- Add remaining reviewed tags

Changes to v2:
- Use a SCSI blacklist flag instead of a hardware handler parameter
  for switching to synchronous ALUA handling
- Move scsi_get_device_flags{,_keyed} to scsi_devinfo.h
- Move flush_delayed_work() into release_port_group()
- Rename alua_lookup_pg() into alua_find_get_pg()
- Add __rcu annotations to keep sparse happy

Changes to v1:
- Include reviews from hch
- Switch to hardware handler parameter instead of module option

Hannes Reinecke (23):
  scsi_dh_alua: Pass buffer as function argument
  scsi_dh_alua: separate out alua_stpg()
  scsi_dh_alua: Make stpg synchronous
  scsi_dh_alua: call alua_rtpg() if stpg fails
  scsi_dh_alua: switch to scsi_execute_req_flags()
  scsi_dh_alua: allocate RTPG buffer separately
  scsi_dh_alua: Use separate alua_port_group structure
  scsi_dh_alua: use unique device id
  scsi_dh_alua: simplify alua_initialize()
  revert commit a8e5a2d593cb ("[SCSI] scsi_dh_alua: ALUA handler attach
    should succeed while TPG is transitioning")
  scsi_dh_alua: move optimize_stpg evaluation
  scsi_dh_alua: remove 'rel_port' from alua_dh_data structure
  scsi_dh_alua: Use workqueue for RTPG
  scsi_dh_alua: Allow workqueue to run synchronously
  scsi_dh_alua: Add new blacklist flag 'BLIST_SYNC_ALUA'
  scsi_dh_alua: Recheck state on unit attention
  scsi_dh_alua: update all port states
  scsi_dh_alua: Send TEST UNIT READY to poll for transitioning
  scsi_dh: add 'rescan' callback
  scsi: Add 'access_state' attribute
  scsi_dh_alua: use common definitions for ALUA state
  scsi_dh_alua: update 'access_state' field
  scsi_dh_alua: Update version to 2.0

 drivers/scsi/device_handler/scsi_dh_alua.c | 979 ++++++++++++++++++++---------
 drivers/scsi/scsi_devinfo.c                |   2 +
 drivers/scsi/scsi_lib.c                    |   1 +
 drivers/scsi/scsi_scan.c                   |  11 +-
 drivers/scsi/scsi_sysfs.c                  |  53 ++
 include/scsi/scsi_device.h                 |   2 +
 include/scsi/scsi_devinfo.h                |   1 +
 include/scsi/scsi_dh.h                     |   2 +
 include/scsi/scsi_proto.h                  |  12 +
 9 files changed, 756 insertions(+), 307 deletions(-)

-- 
1.8.5.6