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scsi_transport_srp: Reduce failover time

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Unlike FC, there is no risk that SCSI devices will be offlined
by the SCSI error handler if the SCSI error handler 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>
Signed-off-by: Doug Ledford <dledford@redhat.com>
This commit is contained in:
Bart Van Assche 2015-05-18 13:24:38 +02:00 committed by Doug Ledford
parent a44074f14b
commit e68ca75200
1 changed files with 8 additions and 1 deletions
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9
drivers/scsi/scsi_transport_srp.c
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@ -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.
@ -628,9 +633,11 @@ 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;
}