[SCSI] fc class: unblock target after calling terminate callback (take 2)

When we block a rport and the driver implements the terminate
callback we will fail IO that was running quickly. However
IO that was in the scsi_device/block queue sits there until
the dev_loss_tmo fires, and this can make it look like IO is
lost because new IO will get executed but that IO stuck in
the blocked queue sits there for some time longer.

With this patch when the fast io fail tmo fires, we will
fail the blocked IO and any new IO. This patch also allows
all drivers to partially support the fast io fail tmo. If the
terminate io callback is not implemented, we will still fail blocked
IO and any new IO, so multipath can handle that.

This patch also allows the fc and iscsi classes to implement the
same behavior. The timers are just unfornately named differently.

This patch also fixes the problem where drivers were unblocking
the target in their terminate callback, which was needed for
rport removal, but for fast io fail timeout it would cause
IO to bounce arround the scsi/block layer and the LLD queuecommand.
And it for drivers that could have IO stuck but did not have
a terminate callback the unblock calls in the class will fix
them.

v2.
- fix up bit setting style to meet JamesS's pref.
- Broke out new host byte error changes to make it easier to read.
- added JamesS's ack from list.
v1
- initial patch

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Acked-by: James Smart <James.Smart@emulex.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/include/scsi/scsi_transport_fc.h b/include/scsi/scsi_transport_fc.h
index 21018a4df452..fb8d01370663 100644
--- a/include/scsi/scsi_transport_fc.h
+++ b/include/scsi/scsi_transport_fc.h
@@ -357,6 +357,7 @@ struct fc_rport {	/* aka fc_starget_attrs */
 /* bit field values for struct fc_rport "flags" field: */
 #define FC_RPORT_DEVLOSS_PENDING        0x01
 #define FC_RPORT_SCAN_PENDING           0x02
+#define FC_RPORT_FAST_FAIL_TIMEDOUT     0x03
 
 #define dev_to_rport(d)                         \
         container_of(d, struct fc_rport, dev)
@@ -683,7 +684,10 @@ fc_remote_port_chkready(struct fc_rport *rport)
                         result = DID_NO_CONNECT << 16;
                 break;
         case FC_PORTSTATE_BLOCKED:
-                result = DID_IMM_RETRY << 16;
+                if (rport->flags & FC_RPORT_FAST_FAIL_TIMEDOUT)
+                        result = DID_NO_CONNECT << 16;
+                else
+                        result = DID_IMM_RETRY << 16;
                 break;
         default:
                 result = DID_NO_CONNECT << 16;