[PATCH 0/6] scsi: Support ALUA unavailable state and INQUIRY changes

[Brian Bunker <brian@purestorage.com>]

The SCSI mid-layer fails to refresh standard INQUIRY data during
rescans. This prevents support for the ALUA "unavailable" state,
where the Peripheral Qualifier (PQ) toggles between 1 and 0.
When a device becomes available, the cached stale PQ prevents
upper-layer drivers from attaching.

Additionally, the Unit Attention for "INQUIRY DATA HAS CHANGED" is
effectively ignored for identification changes because the rescan
does not update standard INQUIRY fields.

Introduce scsi_update_inquiry_data() to refresh the PQ, device type,
and identification strings. Use a new inquiry_mutex to protect
concurrent sysfs access while the buffer is reallocated.

If a rescan detects a change in PQ or device type, trigger
device_reprobe() to automatically match and attach the correct
driver.

Fixes added:
- ALUA/UA Fix: Refreshes standard INQUIRY data on rescan.
- Safety: Uses kmemdup and a mutex to prevent Use-After-Free.
- Deadlock Avoidance: Drops device_lock before reprobing.

Brian Bunker (6):
  scsi: Add INQUIRY data field definitions and accessor helpers
  scsi: Protect INQUIRY sysfs attributes with mutex
  scsi: Add scsi_update_inquiry_data() for updating INQUIRY data
  scsi: Refactor scsi_add_lun() to use scsi_update_inquiry_data()
  scsi: Add device reprobe support to scsi_rescan_device()
  scsi: Handle reprobe for existing devices during SCSI scan

 drivers/scsi/scsi.c        | 164 +++++++++++++++++++
 drivers/scsi/scsi_scan.c   | 321 +++++++++++++++++++++++++------------
 drivers/scsi/scsi_sysfs.c  |  74 ++++++++-
 include/scsi/scsi.h        | 171 ++++++++++++++++++++
 include/scsi/scsi_device.h |  13 ++
 5 files changed, 635 insertions(+), 108 deletions(-)

-- 
2.50.1 (Apple Git-155)