[SCSI] libsas: don't recover end devices attached to disabled phys

If userspace has decided to disable a phy the kernel should honor that
and not inadvertantly re-enable the phy via error recovery. This is
more straightforward in the sata case where link recovery (via
libata-eh) is separate from sas_task cancelling in libsas-eh. Teach
libsas to accept -ENODEV as a successful response from I_T_nexus_reset
('successful' in terms of not escalating further).

This is a more comprehensive fix then "libsas: don't recover 'gone'
devices in sas_ata_hard_reset()", as it is no longer sata-specific.

aic94xx does check the return value from sas_phy_reset() so if the phy
is disabled we proceed with clearing the I_T_nexus.

Signed-off-by: Dan Williams <[e-mail]>
Signed-off-by: James Bottomley <[e-mail]>

drivers/scsi/aic94xx/aic94xx_tmf.c

···
 	ASD_DPRINTK("sending %s reset to %s\n",
 		    reset_type ? "hard" : "soft", dev_name(&phy->dev));
 	res = sas_phy_reset(phy, reset_type);
-	if (res == TMF_RESP_FUNC_COMPLETE) {
+	if (res == TMF_RESP_FUNC_COMPLETE || res == -ENODEV) {
 		/* wait for the maximum settle time */
 		msleep(500);
 		/* clear all outstanding commands (keep nexus suspended) */

drivers/scsi/libsas/sas_ata.c

···
 	struct domain_device *dev = ap->private_data;
 	struct sas_internal *i = dev_to_sas_internal(dev);
 
-	if (test_bit(SAS_DEV_GONE, &dev->state))
-		return -ENODEV;
-
 	res = i->dft->lldd_I_T_nexus_reset(dev);
+	if (res == -ENODEV)
+		return res;
 
 	if (res != TMF_RESP_FUNC_COMPLETE)
 		sas_ata_printk(KERN_DEBUG, dev, "Unable to reset ata device?\n");

drivers/scsi/libsas/sas_init.c

···
 	int ret;
 	enum phy_func reset_type;
 
+	if (!phy->enabled)
+		return -ENODEV;
+
 	if (hard_reset)
 		reset_type = PHY_FUNC_HARD_RESET;
 	else

drivers/scsi/libsas/sas_scsi_host.c

···
 			SAS_DPRINTK("task 0x%p is not at LU: I_T recover\n",
 				    task);
 			tmf_resp = sas_recover_I_T(task->dev);
-			if (tmf_resp == TMF_RESP_FUNC_COMPLETE) {
+			if (tmf_resp == TMF_RESP_FUNC_COMPLETE ||
+			    tmf_resp == -ENODEV) {
 				struct domain_device *dev = task->dev;
 				SAS_DPRINTK("I_T %016llx recovered\n",
 					    SAS_ADDR(task->dev->sas_addr));