[SCSI] scsi_dh: add generic SPC-3 alua handler

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

4 files changed, 814 insertions, 0 deletions

diff --git a/drivers/scsi/device_handler/Kconfig b/drivers/scsi/device_handler/Kconfig
index 2adc0f666b68..67070257919f 100644
--- a/drivers/scsi/device_handler/Kconfig
+++ b/drivers/scsi/device_handler/Kconfig
@@ -30,3 +30,11 @@ config SCSI_DH_EMC
         depends on SCSI_DH
         help
         If you have a EMC CLARiiON select y. Otherwise, say N.
+
+config SCSI_DH_ALUA
+        tristate "SPC-3 ALUA Device Handler (EXPERIMENTAL)"
+        depends on SCSI_DH && EXPERIMENTAL
+        help
+          SCSI Device handler for generic SPC-3 Asymmetric Logical Unit
+          Access (ALUA).
+
diff --git a/drivers/scsi/device_handler/Makefile b/drivers/scsi/device_handler/Makefile
index 35272e93b1c8..e1d2ea083e15 100644
--- a/drivers/scsi/device_handler/Makefile
+++ b/drivers/scsi/device_handler/Makefile
@@ -5,3 +5,4 @@ obj-$(CONFIG_SCSI_DH)		+= scsi_dh.o
 obj-$(CONFIG_SCSI_DH_RDAC)      += scsi_dh_rdac.o
 obj-$(CONFIG_SCSI_DH_HP_SW)     += scsi_dh_hp_sw.o
 obj-$(CONFIG_SCSI_DH_EMC)       += scsi_dh_emc.o
+obj-$(CONFIG_SCSI_DH_ALUA)      += scsi_dh_alua.o
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
new file mode 100644
index 000000000000..6e464488bcab
--- /dev/null
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -0,0 +1,802 @@
+/*
+ * Generic SCSI-3 ALUA SCSI Device Handler
+ *
+ * Copyright (C) 2007, 2008 Hannes Reinecke, SUSE Linux Products GmbH.
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ */
+#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 TPGS_STATE_OPTIMIZED            0x0
+#define TPGS_STATE_NONOPTIMIZED         0x1
+#define TPGS_STATE_STANDBY              0x2
+#define TPGS_STATE_UNAVAILABLE          0x3
+#define TPGS_STATE_OFFLINE              0xe
+#define TPGS_STATE_TRANSITIONING        0xf
+
+#define TPGS_SUPPORT_NONE               0x00
+#define TPGS_SUPPORT_OPTIMIZED          0x01
+#define TPGS_SUPPORT_NONOPTIMIZED       0x02
+#define TPGS_SUPPORT_STANDBY            0x04
+#define TPGS_SUPPORT_UNAVAILABLE        0x08
+#define TPGS_SUPPORT_OFFLINE            0x40
+#define TPGS_SUPPORT_TRANSITION         0x80
+
+#define TPGS_MODE_UNINITIALIZED          -1
+#define TPGS_MODE_NONE                  0x0
+#define TPGS_MODE_IMPLICIT              0x1
+#define TPGS_MODE_EXPLICIT              0x2
+
+#define ALUA_INQUIRY_SIZE               36
+#define ALUA_FAILOVER_TIMEOUT           (60 * HZ)
+#define ALUA_FAILOVER_RETRIES           5
+
+struct alua_dh_data {
+        int                     group_id;
+        int                     rel_port;
+        int                     tpgs;
+        int                     state;
+        unsigned char           inq[ALUA_INQUIRY_SIZE];
+        unsigned char           *buff;
+        int                     bufflen;
+        unsigned char           sense[SCSI_SENSE_BUFFERSIZE];
+        int                     senselen;
+};
+
+#define ALUA_POLICY_SWITCH_CURRENT      0
+#define ALUA_POLICY_SWITCH_ALL          1
+
+static inline struct alua_dh_data *get_alua_data(struct scsi_device *sdev)
+{
+        struct scsi_dh_data *scsi_dh_data = sdev->scsi_dh_data;
+        BUG_ON(scsi_dh_data == NULL);
+        return ((struct alua_dh_data *) scsi_dh_data->buf);
+}
+
+static int realloc_buffer(struct alua_dh_data *h, unsigned len)
+{
+        if (h->buff && h->buff != h->inq)
+                kfree(h->buff);
+
+        h->buff = kmalloc(len, GFP_NOIO);
+        if (!h->buff) {
+                h->buff = h->inq;
+                h->bufflen = ALUA_INQUIRY_SIZE;
+                return 1;
+        }
+        h->bufflen = len;
+        return 0;
+}
+
+static struct request *get_alua_req(struct scsi_device *sdev,
+                                    void *buffer, unsigned buflen, int rw)
+{
+        struct request *rq;
+        struct request_queue *q = sdev->request_queue;
+
+        rq = blk_get_request(q, rw, GFP_NOIO);
+
+        if (!rq) {
+                sdev_printk(KERN_INFO, sdev,
+                            "%s: blk_get_request failed\n", __FUNCTION__);
+                return NULL;
+        }
+
+        if (buflen && blk_rq_map_kern(q, rq, buffer, buflen, GFP_NOIO)) {
+                blk_put_request(rq);
+                sdev_printk(KERN_INFO, sdev,
+                            "%s: blk_rq_map_kern failed\n", __FUNCTION__);
+                return NULL;
+        }
+
+        rq->cmd_type = REQ_TYPE_BLOCK_PC;
+        rq->cmd_flags |= REQ_FAILFAST | REQ_NOMERGE;
+        rq->retries = ALUA_FAILOVER_RETRIES;
+        rq->timeout = ALUA_FAILOVER_TIMEOUT;
+
+        return rq;
+}
+
+/*
+ * submit_std_inquiry - Issue a standard INQUIRY command
+ * @sdev: sdev the command should be send to
+ */
+static int submit_std_inquiry(struct scsi_device *sdev, struct alua_dh_data *h)
+{
+        struct request *rq;
+        int err = SCSI_DH_RES_TEMP_UNAVAIL;
+
+        rq = get_alua_req(sdev, h->inq, ALUA_INQUIRY_SIZE, READ);
+        if (!rq)
+                goto done;
+
+        /* Prepare the command. */
+        rq->cmd[0] = INQUIRY;
+        rq->cmd[1] = 0;
+        rq->cmd[2] = 0;
+        rq->cmd[4] = ALUA_INQUIRY_SIZE;
+        rq->cmd_len = COMMAND_SIZE(INQUIRY);
+
+        rq->sense = h->sense;
+        memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
+        rq->sense_len = h->senselen = 0;
+
+        err = blk_execute_rq(rq->q, NULL, rq, 1);
+        if (err == -EIO) {
+                sdev_printk(KERN_INFO, sdev,
+                            "%s: std inquiry failed with %x\n",
+                            ALUA_DH_NAME, rq->errors);
+                h->senselen = rq->sense_len;
+                err = SCSI_DH_IO;
+        }
+        blk_put_request(rq);
+done:
+        return err;
+}
+
+/*
+ * submit_vpd_inquiry - Issue an INQUIRY VPD page 0x83 command
+ * @sdev: sdev the command should be sent to
+ */