[0/5] scsi: Support to handle Intermittent errors

Message

Muneendra Kumar M Aug. 5, 2020, 2:50 a.m. UTC

This patch adds a support to prevent retries of all the pending/inflight
io's after an abort succeeds on a particular device when transport
connectivity to the device is encountering intermittent errors.

Intermittent connectivity is a condition that can be detected by transport
fabric notifications. A service can monitor the ELS notifications and
take action on all the outstanding io's of a scsi device at that instant.


This feature is intended to be used when the device is part of a multipath
environment. When the service detects the poor connectivity, the multipath
path can be placed in a marginal path group and ignored further io
operations.

After placing a path in the marginal path group,the daemon sets a bit in
scmd->state for all the outstanding io's on that particular device with
the new sysfs interface provided in this patch.This prevent retries of 
all the pending/inflight io's if an io hits a scsi timeout which inturn
issues an abort.On Abort succeeds on a marginal path the io will be
immediately retried on another active path.On abort fails then the things
escalates to existing target reset sg interface recovery process.

Below is the interface provided to abort the io
echo 1 >> /sys/class/fc_transport/targetX\:Y\:Z/noretries_abort

The patches were cut against  5.9/scsi-queue tree

Muneendra (5):
  scsi: Added a new macro in scsi_cmnd.h
  scsi: Clear state bit SCMD_NORETRIES_ABORT of scsi_cmd before start
    request
  scsi: No retries on abort success
  scsi: Added routine to set SCMD_NORETRIES_ABORT bit for outstanding io
    on scsi_dev
  scsi_transport_fc: Added a new sysfs attribute noretries_abort

 drivers/scsi/scsi_error.c        | 63 ++++++++++++++++++++++++++++++++++++++++
 drivers/scsi/scsi_lib.c          |  8 +++--
 drivers/scsi/scsi_priv.h         |  1 +
 drivers/scsi/scsi_transport_fc.c | 49 +++++++++++++++++++++++++++++--
 include/scsi/scsi_cmnd.h         |  3 ++
 5 files changed, 120 insertions(+), 4 deletions(-)