Hi all, during testing we found that there is an issue with dev_loss_tmo and devices in ALUA transitioning state. What happens is that I/O gets requeued via BLK_STS_RESOURCE for these devices, so when dev_loss_tmo triggers the SCSI core cannot flush the request list as I/O is simply requeued. So when the driver is trying to re-establish the device it'll wait for that last reference to drop in order to re-attach the device, but as I/O is still outstanding on the (old) device it'll wait for ever. Fix this by returning 'BLK_STS_AGAIN' from scsi_dh_alua when the device is in ALUA transitioning, and also set the 'transitioning' state when scsi_dh_alua is receiving a sense code, and not only after scsi_dh_alua successfully received the response to a REPORT TARGET PORT GROUPS command. Hannes Reinecke (4): block: return status code in blk_mq_end_request() scsi_dh_alua: return BLK_STS_AGAIN for ALUA transitioning state scsi_dh_alua: set 'transitioning' state on unit attention scsi: return BLK_STS_AGAIN for ALUA transitioning block/blk-mq.c | 2 +- drivers/scsi/device_handler/scsi_dh_alua.c | 10 +++++++++- drivers/scsi/scsi_lib.c | 8 ++++++++ 3 files changed, 18 insertions(+), 2 deletions(-) -- 2.16.4
