[PATCH v2 0/1] scsi: scsi_dh_alua: use device timeout instead of constant

[Brian Bunker <brian@purestorage.com>]

This patch changes the ALUA device handler to use the SCSI device's
configured timeout (rq_timeout) instead of the hardcoded 60-second
ALUA_FAILOVER_TIMEOUT constant. This allows administrators to control
ALUA-related timeouts via the standard SCSI device timeout sysfs
interface (/sys/block/sdX/device/timeout).

Changes in v2:
- Added READ_ONCE() when accessing sdev->request_queue->rq_timeout
  since this value can be modified dynamically by userspace via sysfs
- Added fallback to ALUA_FAILOVER_TIMEOUT if rq_timeout is 0, using
  the ?: operator, to handle any edge cases where the timeout might
  be uninitialized (though sysfs store functions reject 0)
- Retained ALUA_FAILOVER_TIMEOUT constant as the fallback value

Regarding dynamic changes to rq_timeout: this is acceptable because
each SCSI command reads the current timeout when issued. If an admin
changes the timeout mid-operation, subsequent commands will use the
new value. This is actually desirable as it allows administrators to
adjust timeouts on the fly during problematic failovers without
reloading modules.

Brian Bunker (1):
  scsi: scsi_dh_alua: use the device timeout rather than a constant

 drivers/scsi/device_handler/scsi_dh_alua.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

-- 
2.50.1 (Apple Git-155)