scsi: scsi_transport_srp: Don't block target in failfast state

If the port is in SRP_RPORT_FAIL_FAST state when srp_reconnect_rport() is
entered, a transition to SDEV_BLOCK would be illegal, and a kernel WARNING
would be triggered. Skip scsi_target_block() in this case.

Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Bart Van Assche <[e-mail]>
Signed-off-by: Martin Wilck <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/scsi_transport_srp.c

···
 	res = mutex_lock_interruptible(&rport->mutex);
 	if (res)
 		goto out;
-	scsi_target_block(&shost->shost_gendev);
+	if (rport->state != SRP_RPORT_FAIL_FAST)
+		/*
+		 * sdev state must be SDEV_TRANSPORT_OFFLINE, transition
+		 * to SDEV_BLOCK is illegal. Calling scsi_target_unblock()
+		 * later is ok though, scsi_internal_device_unblock_nowait()
+		 * treats SDEV_TRANSPORT_OFFLINE like SDEV_BLOCK.
+		 */
+		scsi_target_block(&shost->shost_gendev);
 	res = rport->state != SRP_RPORT_LOST ? i->f->reconnect(rport) : -ENODEV;
 	pr_debug("%s (state %d): transport.reconnect() returned %d\n",
 		 dev_name(&shost->shost_gendev), rport->state, res);