On 2023/7/24 7:44, Wenchao Hao wrote:
The origin error handle would set host to recovery state and perform error recovery operations, and makes all LUNs which share a same host can not handle IOs. This phenomenon is unbearable for systems which deploy many LUNs in one HBA.
Friendly PING... We can reduce probability of blocking whole host when handle error commands with this patchset, which is important for servers which deploy large scale disks. And the new error handler is not enabled default, so it would not affect drivers which do not need it.
This patchset introduce support for LUN/target based error handle, drivers can chose if to implement it. They can implement LUN, target or both of LUN and target based error handle by their own error handle strategy. The first patch defined this framework, it abstract three key operations which are: add error command, wake up error handle, block ios when error command is added and recoverying. Drivers should implement these three function callbacks and setup to SCSI middle level. Besides the basic framework, this patchset also add a basic LUN/target based error handle strategy. For LUN based eh, it would try check sense, start unit and reset LUN, if all above steps can not recovery all error commands, fallback to further recovery like tartget based (if implemented) or host based error handle. It's same for tartget based eh, it would try check sense, start unit, reset LUN and reset target. If all above steps can not recovery all error commands, fallback to further recovery which is host based error handle. This patchset is tested by scsi_debug which support single LUN error injection, the scsi_debug patches is here: https://lore.kernel.org/linux-scsi/20230723234105.1628982-1-haowenchao2@xxxxxxxxxx/T/#t Wenchao Hao (13): scsi: Define basic framework for driver LUN/target based error handle scsi:scsi_error: Move complete variable eh_action from shost to sdevice scsi:scsi_error: Check if to do reset in scsi_try_xxx_reset scsi:scsi_error: Add helper scsi_eh_sdev_stu to do START_UNIT scsi:scsi_error: Add helper scsi_eh_sdev_reset to do lun reset scsi:scsi_error: Add flags to mark error handle steps has done scsi:scsi_error: Define helper to perform LUN based error handle scsi:scsi_error: Add LUN based error handler based previous helper scsi:core: increase/decrease target_busy without check can_queue scsi:scsi_error: Define helper to perform target based error handle scsi:scsi_error: Add target based error handler based previous helper scsi:scsi_debug: Add param to control if setup LUN based error handle scsi:scsi_debug: Add param to control if setup target based error handle drivers/scsi/scsi_debug.c | 19 + drivers/scsi/scsi_error.c | 705 ++++++++++++++++++++++++++++++++++--- drivers/scsi/scsi_lib.c | 23 +- drivers/scsi/scsi_priv.h | 20 ++ include/scsi/scsi_device.h | 97 +++++ include/scsi/scsi_eh.h | 4 + include/scsi/scsi_host.h | 2 - 7 files changed, 813 insertions(+), 57 deletions(-)
