scsi_transport_srp: Block rport upon TL error even with fast_io_fail_tmo = off

The current behavior of the SRP transport layer when a transport layer
error is encountered is to block SCSI command processing only if
fast_io_fail_tmo != off.  The current behavior of the FC transport
layer when a transport layer error is encountered is to block SCSI
command processing no matter which value fast_io_fail_tmo has been set
to.  Make the behavior of the SRP transport layer consistent with that
of the FC transport layer to avoid confusion.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>

1 files changed, 17 insertions, 13 deletions

diff --git a/drivers/scsi/scsi_transport_srp.c b/drivers/scsi/scsi_transport_srp.c
index 2700a5a09bd4..8b9cb22be963 100644
--- a/drivers/scsi/scsi_transport_srp.c
+++ b/drivers/scsi/scsi_transport_srp.c
@@ -67,7 +67,8 @@ static inline struct Scsi_Host *rport_to_shost(struct srp_rport *r)
  *
  * The combination of the timeout parameters must be such that SCSI commands
  * are finished in a reasonable time. Hence do not allow the fast I/O fail
- * timeout to exceed SCSI_DEVICE_BLOCK_MAX_TIMEOUT. Furthermore, these
+ * timeout to exceed SCSI_DEVICE_BLOCK_MAX_TIMEOUT nor allow dev_loss_tmo to
+ * exceed that limit if failing I/O fast has been disabled. Furthermore, these
  * parameters must be such that multipath can detect failed paths timely.
  * Hence do not allow all three parameters to be disabled simultaneously.
  */
@@ -79,6 +80,9 @@ int srp_tmo_valid(int reconnect_delay, int fast_io_fail_tmo, int dev_loss_tmo)
                 return -EINVAL;
         if (fast_io_fail_tmo > SCSI_DEVICE_BLOCK_MAX_TIMEOUT)
                 return -EINVAL;
+        if (fast_io_fail_tmo < 0 &&
+            dev_loss_tmo > SCSI_DEVICE_BLOCK_MAX_TIMEOUT)
+                return -EINVAL;
         if (dev_loss_tmo >= LONG_MAX / HZ)
                 return -EINVAL;
         if (fast_io_fail_tmo >= 0 && dev_loss_tmo >= 0 &&
@@ -463,20 +467,20 @@ static void __srp_start_tl_fail_timers(struct srp_rport *rport)
                         queue_delayed_work(system_long_wq,
                                            &rport->reconnect_work,
                                            1UL * delay * HZ);
-                if (fast_io_fail_tmo >= 0 &&
-                    srp_rport_set_state(rport, SRP_RPORT_BLOCKED) == 0) {
+                if (srp_rport_set_state(rport, SRP_RPORT_BLOCKED) == 0) {
                         pr_debug("%s new state: %d\n",
                                  dev_name(&shost->shost_gendev),
                                  rport->state);
                         scsi_target_block(&shost->shost_gendev);
-                        queue_delayed_work(system_long_wq,
-                                           &rport->fast_io_fail_work,
-                                           1UL * fast_io_fail_tmo * HZ);
+                        if (fast_io_fail_tmo >= 0)
+                                queue_delayed_work(system_long_wq,
+                                                   &rport->fast_io_fail_work,
+                                                   1UL * fast_io_fail_tmo * HZ);
+                        if (dev_loss_tmo >= 0)
+                                queue_delayed_work(system_long_wq,
+                                                   &rport->dev_loss_work,
+                                                   1UL * dev_loss_tmo * HZ);
                 }
-                if (dev_loss_tmo >= 0)
-                        queue_delayed_work(system_long_wq,
-                                           &rport->dev_loss_work,
-                                           1UL * dev_loss_tmo * HZ);
         } else {
                 pr_debug("%s has already been deleted\n",
                          dev_name(&shost->shost_gendev));
@@ -578,9 +582,9 @@ int srp_reconnect_rport(struct srp_rport *rport)
                 spin_unlock_irq(shost->host_lock);
         } else if (rport->state == SRP_RPORT_RUNNING) {
                 /*
-                 * srp_reconnect_rport() was invoked with fast_io_fail
-                 * off. Mark the port as failed and start the TL failure
-                 * timers if these had not yet been started.
+                 * srp_reconnect_rport() has been invoked with fast_io_fail
+                 * and dev_loss off. Mark the port as failed and start the TL
+                 * failure timers if these had not yet been started.
                  */
                 __rport_fail_io_fast(rport);
                 scsi_target_unblock(&shost->shost_gendev,