[PATCH 06/12] scsi_transport_srp: Reduce failover time

Bart Van Assche
2015-04-30T08:59:45Z

Unlike FC, there is no risk that SCSI devices will be offlined
by the error handler if it is started while a reconnect attempt
is ongoing. Hence report timeout errors as soon as possible
if a higher software layer (e.g. multipathd) needs to be informed
about a timeout. It is assumed that if both fast_io_fail_tmo < 0
and rport->dev_loss_tmo < 0 that this means that there is no
need to report timeouts quickly.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: James Bottomley <JBottomley@Odin.com>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: Sebastian Parschauer <sebastian.riemer@profitbricks.com>
---
drivers/scsi/scsi_transport_srp.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi_transport_srp.c b/drivers/scsi/scsi_transport_srp.c
index 4a44337..6667c2b 100644
--- a/drivers/scsi/scsi_transport_srp.c
+++ b/drivers/scsi/scsi_transport_srp.c
@@ -61,6 +61,11 @@ static inline struct Scsi_Host *rport_to_shost(struct srp_rport *r)
return dev_to_shost(r->dev.parent);
}

+static inline struct srp_rport *shost_to_rport(struct Scsi_Host *shost)
+{
+ return transport_class_to_srp_rport(&shost->shost_gendev);
+}
+
/**
* srp_tmo_valid() - check timeout combination validity
* @reconnect_delay: Reconnect delay in seconds.
@@ -626,9 +631,11 @@ static enum blk_eh_timer_return srp_timed_out(struct scsi_cmnd *scmd)
struct scsi_device *sdev = scmd->device;
struct Scsi_Host *shost = sdev->host;
struct srp_internal *i = to_srp_internal(shost->transportt);
+ struct srp_rport *rport = shost_to_rport(shost);

pr_debug("timeout for sdev %s\n", dev_name(&sdev->sdev_gendev));
- return i->f->reset_timer_if_blocked && scsi_device_blocked(sdev) ?
+ return rport->fast_io_fail_tmo < 0 && rport->dev_loss_tmo < 0 &&
+ i->f->reset_timer_if_blocked && scsi_device_blocked(sdev) ?
BLK_EH_RESET_TIMER : BLK_EH_NOT_HANDLED;
}

--
2.1.4