[SCSI] scsi_dh_alua: Handle all states correctly

For ALUA we should be handling all states, independent of whether
the mode is explicit or implicit. For 'Transitioning' we should retry
for a certain amount of time; after that we're setting the port
to 'Standby' and return SCSI_DH_RETRY to signal upper layers
a retry is in order here.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 38 insertions, 27 deletions

diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 1a970a76b1b9..6b729324b8d3 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -1,7 +1,7 @@
 /*
  * Generic SCSI-3 ALUA SCSI Device Handler
  *
- * Copyright (C) 2007, 2008 Hannes Reinecke, SUSE Linux Products GmbH.
+ * Copyright (C) 2007-2010 Hannes Reinecke, SUSE Linux Products GmbH.
  * All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
@@ -20,17 +20,19 @@
  *
  */
 #include <linux/slab.h>
+#include <linux/delay.h>
 #include <scsi/scsi.h>
 #include <scsi/scsi_eh.h>
 #include <scsi/scsi_dh.h>
 
 #define ALUA_DH_NAME "alua"
-#define ALUA_DH_VER "1.2"
+#define ALUA_DH_VER "1.3"
 
 #define TPGS_STATE_OPTIMIZED            0x0
 #define TPGS_STATE_NONOPTIMIZED         0x1
 #define TPGS_STATE_STANDBY              0x2
 #define TPGS_STATE_UNAVAILABLE          0x3
+#define TPGS_STATE_LBA_DEPENDENT        0x4
 #define TPGS_STATE_OFFLINE              0xe
 #define TPGS_STATE_TRANSITIONING        0xf
 
@@ -39,6 +41,7 @@
 #define TPGS_SUPPORT_NONOPTIMIZED       0x02
 #define TPGS_SUPPORT_STANDBY            0x04
 #define TPGS_SUPPORT_UNAVAILABLE        0x08
+#define TPGS_SUPPORT_LBA_DEPENDENT      0x10
 #define TPGS_SUPPORT_OFFLINE            0x40
 #define TPGS_SUPPORT_TRANSITION         0x80
 
@@ -460,6 +463,8 @@ static char print_alua_state(int state)
                 return 'S';
         case TPGS_STATE_UNAVAILABLE:
                 return 'U';
+        case TPGS_STATE_LBA_DEPENDENT:
+                return 'L';
         case TPGS_STATE_OFFLINE:
                 return 'O';
         case TPGS_STATE_TRANSITIONING:
@@ -542,7 +547,9 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
         int len, k, off, valid_states = 0;
         char *ucp;
         unsigned err;
+        unsigned long expiry, interval = 10;
 
+        expiry = round_jiffies_up(jiffies + ALUA_FAILOVER_TIMEOUT);
  retry:
         err = submit_rtpg(sdev, h);
 
@@ -553,7 +560,7 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
                         return SCSI_DH_IO;
 
                 err = alua_check_sense(sdev, &sense_hdr);
-                if (err == ADD_TO_MLQUEUE)
+                if (err == ADD_TO_MLQUEUE && time_before(jiffies, expiry))
                         goto retry;
                 sdev_printk(KERN_INFO, sdev,
                             "%s: rtpg sense code %02x/%02x/%02x\n",
@@ -587,38 +594,37 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
         }
 
         sdev_printk(KERN_INFO, sdev,
-                    "%s: port group %02x state %c supports %c%c%c%c%c%c\n",
+                    "%s: port group %02x state %c supports %c%c%c%c%c%c%c\n",
                     ALUA_DH_NAME, h->group_id, print_alua_state(h->state),
                     valid_states&TPGS_SUPPORT_TRANSITION?'T':'t',
                     valid_states&TPGS_SUPPORT_OFFLINE?'O':'o',
+                    valid_states&TPGS_SUPPORT_LBA_DEPENDENT?'L':'l',
                     valid_states&TPGS_SUPPORT_UNAVAILABLE?'U':'u',
                     valid_states&TPGS_SUPPORT_STANDBY?'S':'s',
                     valid_states&TPGS_SUPPORT_NONOPTIMIZED?'N':'n',
                     valid_states&TPGS_SUPPORT_OPTIMIZED?'A':'a');
 
-        if (h->tpgs & TPGS_MODE_EXPLICIT) {
-                switch (h->state) {
-                case TPGS_STATE_TRANSITIONING:
+        switch (h->state) {
+        case TPGS_STATE_TRANSITIONING:
+                if (time_before(jiffies, expiry)) {
                         /* State transition, retry */
+                        interval *= 10;
+                        msleep(interval);
                         goto retry;
-                        break;
-                case TPGS_STATE_OFFLINE:
-                        /* Path is offline, fail */
-                        err = SCSI_DH_DEV_OFFLINED;
-                        break;
-                default:
-                        break;
                 }
-        } else {
-                /* Only Implicit ALUA support */
-                if (h->state == TPGS_STATE_OPTIMIZED ||
-                    h->state == TPGS_STATE_NONOPTIMIZED ||
-                    h->state == TPGS_STATE_STANDBY)
-                        /* Useable path if active */
-                        err = SCSI_DH_OK;
-                else
-                        /* Path unuseable for unavailable/offline */
-                        err = SCSI_DH_DEV_OFFLINED;
+                /* Transitioning time exceeded, set port to standby */
+                err = SCSI_DH_RETRY;
+                h->state = TPGS_STATE_STANDBY;
+                break;
+        case TPGS_STATE_OFFLINE:
+        case TPGS_STATE_UNAVAILABLE:
+                /* Path unuseable for unavailable/offline */
+                err = SCSI_DH_DEV_OFFLINED;
+                break;
+        default:
+                /* Useable path if active */
+                err = SCSI_DH_OK;
+                break;
         }
         return err;
 }
@@ -672,7 +678,9 @@ static int alua_activate(struct scsi_device *sdev,
                         goto out;
         }
 
-        if (h->tpgs & TPGS_MODE_EXPLICIT && h->state != TPGS_STATE_OPTIMIZED) {
+        if (h->tpgs & TPGS_MODE_EXPLICIT &&
+            h->state != TPGS_STATE_OPTIMIZED &&
+            h->state != TPGS_STATE_LBA_DEPENDENT) {
                 h->callback_fn = fn;
                 h->callback_data = data;
                 err = submit_stpg(h);
@@ -698,8 +706,11 @@ static int alua_prep_fn(struct scsi_device *sdev, struct request *req)
         struct alua_dh_data *h = get_alua_data(sdev);
         int ret = BLKPREP_OK;
 
-        if (h->state != TPGS_STATE_OPTIMIZED &&
-            h->state != TPGS_STATE_NONOPTIMIZED) {
+        if (h->state == TPGS_STATE_TRANSITIONING)
+                ret = BLKPREP_DEFER;
+        else if (h->state != TPGS_STATE_OPTIMIZED &&
+                 h->state != TPGS_STATE_NONOPTIMIZED &&
+                 h->state != TPGS_STATE_LBA_DEPENDENT) {
                 ret = BLKPREP_KILL;
                 req->cmd_flags |= REQ_QUIET;
         }