scsi_dh_rdac.c

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/*
 * LSI/Engenio/NetApp E-Series RDAC SCSI Device Handler
 *
 * Copyright (C) 2005 Mike Christie. All rights reserved.
 * Copyright (C) Chandra Seetharaman, IBM Corp. 2007
 *
 * 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>
#include <linux/workqueue.h>
#include <linux/slab.h>
#include <linux/module.h>

#define RDAC_NAME "rdac"
#define RDAC_RETRY_COUNT 5

/*
 * LSI mode page stuff
 *
 * These struct definitions and the forming of the
 * mode page were taken from the LSI RDAC 2.4 GPL'd
 * driver, and then converted to Linux conventions.
 */
#define RDAC_QUIESCENCE_TIME 20
/*
 * Page Codes
 */
#define RDAC_PAGE_CODE_REDUNDANT_CONTROLLER 0x2c

/*
 * Controller modes definitions
 */
#define RDAC_MODE_TRANSFER_SPECIFIED_LUNS   0x02

/*
 * RDAC Options field
 */
#define RDAC_FORCED_QUIESENCE 0x02

#define RDAC_TIMEOUT    (60 * HZ)
#define RDAC_RETRIES    3

struct rdac_mode_6_hdr {
    u8  data_len;
    u8  medium_type;
    u8  device_params;
    u8  block_desc_len;
};

struct rdac_mode_10_hdr {
    u16 data_len;
    u8  medium_type;
    u8  device_params;
    u16 reserved;
    u16 block_desc_len;
};

struct rdac_mode_common {
    u8  controller_serial[16];
    u8  alt_controller_serial[16];
    u8  rdac_mode[2];
    u8  alt_rdac_mode[2];
    u8  quiescence_timeout;
    u8  rdac_options;
};

struct rdac_pg_legacy {
    struct rdac_mode_6_hdr hdr;
    u8  page_code;
    u8  page_len;
    struct rdac_mode_common common;
#define MODE6_MAX_LUN   32
    u8  lun_table[MODE6_MAX_LUN];
    u8  reserved2[32];
    u8  reserved3;
    u8  reserved4;
};

struct rdac_pg_expanded {
    struct rdac_mode_10_hdr hdr;
    u8  page_code;
    u8  subpage_code;
    u8  page_len[2];
    struct rdac_mode_common common;
    u8  lun_table[256];
    u8  reserved3;
    u8  reserved4;
};

struct c9_inquiry {
    u8  peripheral_info;
    u8  page_code;  /* 0xC9 */
    u8  reserved1;
    u8  page_len;
    u8  page_id[4]; /* "vace" */
    u8  avte_cvp;
    u8  path_prio;
    u8  reserved2[38];
};

#define SUBSYS_ID_LEN   16
#define SLOT_ID_LEN 2
#define ARRAY_LABEL_LEN 31

struct c4_inquiry {
    u8  peripheral_info;
    u8  page_code;  /* 0xC4 */
    u8  reserved1;
    u8  page_len;
    u8  page_id[4]; /* "subs" */
    u8  subsys_id[SUBSYS_ID_LEN];
    u8  revision[4];
    u8  slot_id[SLOT_ID_LEN];
    u8  reserved[2];
};

#define UNIQUE_ID_LEN 16
struct c8_inquiry {
    u8  peripheral_info;
    u8  page_code; /* 0xC8 */
    u8  reserved1;
    u8  page_len;
    u8  page_id[4]; /* "edid" */
    u8  reserved2[3];
    u8  vol_uniq_id_len;
    u8  vol_uniq_id[16];
    u8  vol_user_label_len;
    u8  vol_user_label[60];
    u8  array_uniq_id_len;
    u8  array_unique_id[UNIQUE_ID_LEN];
    u8  array_user_label_len;
    u8  array_user_label[60];
    u8  lun[8];
};

struct rdac_controller {
    u8          array_id[UNIQUE_ID_LEN];
    int         use_ms10;
    struct kref     kref;
    struct list_head    node; /* list of all controllers */
    union           {
        struct rdac_pg_legacy legacy;
        struct rdac_pg_expanded expanded;
    } mode_select;
    u8  index;
    u8  array_name[ARRAY_LABEL_LEN];
    struct Scsi_Host    *host;
    spinlock_t      ms_lock;
    int         ms_queued;
    struct work_struct  ms_work;
    struct scsi_device  *ms_sdev;
    struct list_head    ms_head;
};

struct c2_inquiry {
    u8  peripheral_info;
    u8  page_code;  /* 0xC2 */
    u8  reserved1;
    u8  page_len;
    u8  page_id[4]; /* "swr4" */
    u8  sw_version[3];
    u8  sw_date[3];
    u8  features_enabled;
    u8  max_lun_supported;
    u8  partitions[239]; /* Total allocation length should be 0xFF */
};

struct rdac_dh_data {
    struct rdac_controller  *ctlr;
#define UNINITIALIZED_LUN   (1 << 8)
    unsigned        lun;

#define RDAC_MODE       0
#define RDAC_MODE_AVT       1
#define RDAC_MODE_IOSHIP    2
    unsigned char       mode;

#define RDAC_STATE_ACTIVE   0
#define RDAC_STATE_PASSIVE  1
    unsigned char       state;

#define RDAC_LUN_UNOWNED    0
#define RDAC_LUN_OWNED      1
    char            lun_state;

#define RDAC_PREFERRED      0
#define RDAC_NON_PREFERRED  1
    char            preferred;

    unsigned char       sense[SCSI_SENSE_BUFFERSIZE];
    union           {
        struct c2_inquiry c2;
        struct c4_inquiry c4;
        struct c8_inquiry c8;
        struct c9_inquiry c9;
    } inq;
};

static const char *mode[] = {
    "RDAC",
    "AVT",
    "IOSHIP",
};
static const char *lun_state[] =
{
    "unowned",
    "owned",
};

struct rdac_queue_data {
    struct list_head    entry;
    struct rdac_dh_data *h;
    activate_complete   callback_fn;
    void            *callback_data;
};

static LIST_HEAD(ctlr_list);
static DEFINE_SPINLOCK(list_lock);
static struct workqueue_struct *kmpath_rdacd;
static void send_mode_select(struct work_struct *work);

/*
 * module parameter to enable rdac debug logging.
 * 2 bits for each type of logging, only two types defined for now
 * Can be enhanced if required at later point
 */
static int rdac_logging = 1;
module_param(rdac_logging, int, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(rdac_logging, "A bit mask of rdac logging levels, "
        "Default is 1 - failover logging enabled, "
        "set it to 0xF to enable all the logs");

#define RDAC_LOG_FAILOVER   0
#define RDAC_LOG_SENSE      2

#define RDAC_LOG_BITS       2

#define RDAC_LOG_LEVEL(SHIFT)  \
    ((rdac_logging >> (SHIFT)) & ((1 << (RDAC_LOG_BITS)) - 1))

#define RDAC_LOG(SHIFT, sdev, f, arg...) \
do { \
    if (unlikely(RDAC_LOG_LEVEL(SHIFT))) \
        sdev_printk(KERN_INFO, sdev, RDAC_NAME ": " f "\n", ## arg); \
} while (0);

static inline struct rdac_dh_data *get_rdac_data(struct scsi_device *sdev)
{
    struct scsi_dh_data *scsi_dh_data = sdev->scsi_dh_data;
    BUG_ON(scsi_dh_data == NULL);
    return ((struct rdac_dh_data *) scsi_dh_data->buf);
}

static struct request *get_rdac_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,
                "get_rdac_req: blk_get_request failed.\n");
        return NULL;
    }

    if (buflen && blk_rq_map_kern(q, rq, buffer, buflen, GFP_NOIO)) {
        blk_put_request(rq);
        sdev_printk(KERN_INFO, sdev,
                "get_rdac_req: blk_rq_map_kern failed.\n");
        return NULL;
    }

    rq->cmd_type = REQ_TYPE_BLOCK_PC;
    rq->cmd_flags |= REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
             REQ_FAILFAST_DRIVER;
    rq->retries = RDAC_RETRIES;
    rq->timeout = RDAC_TIMEOUT;

    return rq;
}

static struct request *rdac_failover_get(struct scsi_device *sdev,
            struct rdac_dh_data *h, struct list_head *list)
{
    struct request *rq;
    struct rdac_mode_common *common;
    unsigned data_size;
    struct rdac_queue_data *qdata;
    u8 *lun_table;

    if (h->ctlr->use_ms10) {
        struct rdac_pg_expanded *rdac_pg;

        data_size = sizeof(struct rdac_pg_expanded);
        rdac_pg = &h->ctlr->mode_select.expanded;
        memset(rdac_pg, 0, data_size);
        common = &rdac_pg->common;
        rdac_pg->page_code = RDAC_PAGE_CODE_REDUNDANT_CONTROLLER + 0x40;
        rdac_pg->subpage_code = 0x1;
        rdac_pg->page_len[0] = 0x01;
        rdac_pg->page_len[1] = 0x28;
        lun_table = rdac_pg->lun_table;
    } else {
        struct rdac_pg_legacy *rdac_pg;

        data_size = sizeof(struct rdac_pg_legacy);
        rdac_pg = &h->ctlr->mode_select.legacy;
        memset(rdac_pg, 0, data_size);
        common = &rdac_pg->common;
        rdac_pg->page_code = RDAC_PAGE_CODE_REDUNDANT_CONTROLLER;
        rdac_pg->page_len = 0x68;
        lun_table = rdac_pg->lun_table;
    }
    common->rdac_mode[1] = RDAC_MODE_TRANSFER_SPECIFIED_LUNS;
    common->quiescence_timeout = RDAC_QUIESCENCE_TIME;
    common->rdac_options = RDAC_FORCED_QUIESENCE;

    list_for_each_entry(qdata, list, entry) {
        lun_table[qdata->h->lun] = 0x81;
    }

    /* get request for block layer packet command */
    rq = get_rdac_req(sdev, &h->ctlr->mode_select, data_size, WRITE);
    if (!rq)
        return NULL;

    /* Prepare the command. */
    if (h->ctlr->use_ms10) {
        rq->cmd[0] = MODE_SELECT_10;
        rq->cmd[7] = data_size >> 8;
        rq->cmd[8] = data_size & 0xff;
    } else {
        rq->cmd[0] = MODE_SELECT;
        rq->cmd[4] = data_size;
    }
    rq->cmd_len = COMMAND_SIZE(rq->cmd[0]);

    rq->sense = h->sense;
    memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
    rq->sense_len = 0;

    return rq;
}

static void release_controller(struct kref *kref)
{
    struct rdac_controller *ctlr;
    ctlr = container_of(kref, struct rdac_controller, kref);

    list_del(&ctlr->node);
    kfree(ctlr);
}

static struct rdac_controller *get_controller(int index, char *array_name,
            u8 *array_id, struct scsi_device *sdev)
{
    struct rdac_controller *ctlr, *tmp;

    list_for_each_entry(tmp, &ctlr_list, node) {
        if ((memcmp(tmp->array_id, array_id, UNIQUE_ID_LEN) == 0) &&
              (tmp->index == index) &&
              (tmp->host == sdev->host)) {
            kref_get(&tmp->kref);
            return tmp;
        }
    }
    ctlr = kmalloc(sizeof(*ctlr), GFP_ATOMIC);
    if (!ctlr)
        return NULL;

    /* initialize fields of controller */
    memcpy(ctlr->array_id, array_id, UNIQUE_ID_LEN);
    ctlr->index = index;
    ctlr->host = sdev->host;
    memcpy(ctlr->array_name, array_name, ARRAY_LABEL_LEN);

    kref_init(&ctlr->kref);
    ctlr->use_ms10 = -1;
    ctlr->ms_queued = 0;
    ctlr->ms_sdev = NULL;
    spin_lock_init(&ctlr->ms_lock);
    INIT_WORK(&ctlr->ms_work, send_mode_select);
    INIT_LIST_HEAD(&ctlr->ms_head);
    list_add(&ctlr->node, &ctlr_list);

    return ctlr;
}

static int submit_inquiry(struct scsi_device *sdev, int page_code,
              unsigned int len, struct rdac_dh_data *h)
{
    struct request *rq;
    struct request_queue *q = sdev->request_queue;
    int err = SCSI_DH_RES_TEMP_UNAVAIL;

    rq = get_rdac_req(sdev, &h->inq, len, READ);
    if (!rq)
        goto done;

    /* Prepare the command. */
    rq->cmd[0] = INQUIRY;
    rq->cmd[1] = 1;
    rq->cmd[2] = page_code;
    rq->cmd[4] = len;
    rq->cmd_len = COMMAND_SIZE(INQUIRY);

    rq->sense = h->sense;
    memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
    rq->sense_len = 0;

    err = blk_execute_rq(q, NULL, rq, 1);
    if (err == -EIO)
        err = SCSI_DH_IO;

    blk_put_request(rq);
done:
    return err;
}

static int get_lun_info(struct scsi_device *sdev, struct rdac_dh_data *h,
            char *array_name, u8 *array_id)
{
    int err, i;
    struct c8_inquiry *inqp;

    err = submit_inquiry(sdev, 0xC8, sizeof(struct c8_inquiry), h);
    if (err == SCSI_DH_OK) {
        inqp = &h->inq.c8;
        if (inqp->page_code != 0xc8)
            return SCSI_DH_NOSYS;
        if (inqp->page_id[0] != 'e' || inqp->page_id[1] != 'd' ||
            inqp->page_id[2] != 'i' || inqp->page_id[3] != 'd')
            return SCSI_DH_NOSYS;
        h->lun = inqp->lun[7]; /* Uses only the last byte */

        for(i=0; i<ARRAY_LABEL_LEN-1; ++i)
            *(array_name+i) = inqp->array_user_label[(2*i)+1];

        *(array_name+ARRAY_LABEL_LEN-1) = '\0';
        memset(array_id, 0, UNIQUE_ID_LEN);
        memcpy(array_id, inqp->array_unique_id, inqp->array_uniq_id_len);
    }
    return err;
}

static int check_ownership(struct scsi_device *sdev, struct rdac_dh_data *h)
{
    int err;
    struct c9_inquiry *inqp;

    h->state = RDAC_STATE_ACTIVE;
    err = submit_inquiry(sdev, 0xC9, sizeof(struct c9_inquiry), h);
    if (err == SCSI_DH_OK) {
        inqp = &h->inq.c9;
        /* detect the operating mode */
        if ((inqp->avte_cvp >> 5) & 0x1)
            h->mode = RDAC_MODE_IOSHIP; /* LUN in IOSHIP mode */
        else if (inqp->avte_cvp >> 7)
            h->mode = RDAC_MODE_AVT; /* LUN in AVT mode */
        else
            h->mode = RDAC_MODE; /* LUN in RDAC mode */

        /* Update ownership */
        if (inqp->avte_cvp & 0x1)
            h->lun_state = RDAC_LUN_OWNED;
        else {
            h->lun_state = RDAC_LUN_UNOWNED;
            if (h->mode == RDAC_MODE)
                h->state = RDAC_STATE_PASSIVE;
        }

        /* Update path prio*/
        if (inqp->path_prio & 0x1)
            h->preferred = RDAC_PREFERRED;
        else
            h->preferred = RDAC_NON_PREFERRED;
    }

    return err;
}

static int initialize_controller(struct scsi_device *sdev,
        struct rdac_dh_data *h, char *array_name, u8 *array_id)
{
    int err, index;
    struct c4_inquiry *inqp;

    err = submit_inquiry(sdev, 0xC4, sizeof(struct c4_inquiry), h);
    if (err == SCSI_DH_OK) {
        inqp = &h->inq.c4;
        /* get the controller index */
        if (inqp->slot_id[1] == 0x31)
            index = 0;
        else
            index = 1;

        spin_lock(&list_lock);
        h->ctlr = get_controller(index, array_name, array_id, sdev);
        if (!h->ctlr)
            err = SCSI_DH_RES_TEMP_UNAVAIL;
        spin_unlock(&list_lock);
    }
    return err;
}

static int set_mode_select(struct scsi_device *sdev, struct rdac_dh_data *h)
{
    int err;
    struct c2_inquiry *inqp;

    err = submit_inquiry(sdev, 0xC2, sizeof(struct c2_inquiry), h);
    if (err == SCSI_DH_OK) {
        inqp = &h->inq.c2;
        /*
         * If more than MODE6_MAX_LUN luns are supported, use
         * mode select 10
         */
        if (inqp->max_lun_supported >= MODE6_MAX_LUN)
            h->ctlr->use_ms10 = 1;
        else
            h->ctlr->use_ms10 = 0;
    }
    return err;
}

static int mode_select_handle_sense(struct scsi_device *sdev,
                    unsigned char *sensebuf)
{
    struct scsi_sense_hdr sense_hdr;
    int err = SCSI_DH_IO, ret;
    struct rdac_dh_data *h = get_rdac_data(sdev);

    ret = scsi_normalize_sense(sensebuf, SCSI_SENSE_BUFFERSIZE, &sense_hdr);
    if (!ret)
        goto done;

    switch (sense_hdr.sense_key) {
    case NO_SENSE:
    case ABORTED_COMMAND:
    case UNIT_ATTENTION:
        err = SCSI_DH_RETRY;
        break;
    case NOT_READY:
        if (sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x01)
            /* LUN Not Ready and is in the Process of Becoming
             * Ready
             */
            err = SCSI_DH_RETRY;
        break;
    case ILLEGAL_REQUEST:
        if (sense_hdr.asc == 0x91 && sense_hdr.ascq == 0x36)
            /*
             * Command Lock contention
             */
            err = SCSI_DH_RETRY;
        break;
    default:
        break;
    }

    RDAC_LOG(RDAC_LOG_FAILOVER, sdev, "array %s, ctlr %d, "
        "MODE_SELECT returned with sense %02x/%02x/%02x",
        (char *) h->ctlr->array_name, h->ctlr->index,
        sense_hdr.sense_key, sense_hdr.asc, sense_hdr.ascq);

done:
    return err;
}

static void send_mode_select(struct work_struct *work)
{
    struct rdac_controller *ctlr =
        container_of(work, struct rdac_controller, ms_work);
    struct request *rq;
    struct scsi_device *sdev = ctlr->ms_sdev;
    struct rdac_dh_data *h = get_rdac_data(sdev);
    struct request_queue *q = sdev->request_queue;
    int err, retry_cnt = RDAC_RETRY_COUNT;
    struct rdac_queue_data *tmp, *qdata;
    LIST_HEAD(list);

    spin_lock(&ctlr->ms_lock);
    list_splice_init(&ctlr->ms_head, &list);
    ctlr->ms_queued = 0;
    ctlr->ms_sdev = NULL;
    spin_unlock(&ctlr->ms_lock);

retry:
    err = SCSI_DH_RES_TEMP_UNAVAIL;
    rq = rdac_failover_get(sdev, h, &list);
    if (!rq)
        goto done;

    RDAC_LOG(RDAC_LOG_FAILOVER, sdev, "array %s, ctlr %d, "
        "%s MODE_SELECT command",
        (char *) h->ctlr->array_name, h->ctlr->index,
        (retry_cnt == RDAC_RETRY_COUNT) ? "queueing" : "retrying");

    err = blk_execute_rq(q, NULL, rq, 1);
    blk_put_request(rq);
    if (err != SCSI_DH_OK) {
        err = mode_select_handle_sense(sdev, h->sense);
        if (err == SCSI_DH_RETRY && retry_cnt--)
            goto retry;
    }
    if (err == SCSI_DH_OK) {
        h->state = RDAC_STATE_ACTIVE;
        RDAC_LOG(RDAC_LOG_FAILOVER, sdev, "array %s, ctlr %d, "
                "MODE_SELECT completed",
                (char *) h->ctlr->array_name, h->ctlr->index);
    }

done:
    list_for_each_entry_safe(qdata, tmp, &list, entry) {
        list_del(&qdata->entry);
        if (err == SCSI_DH_OK)
            qdata->h->state = RDAC_STATE_ACTIVE;
        if (qdata->callback_fn)
            qdata->callback_fn(qdata->callback_data, err);
        kfree(qdata);
    }
    return;
}

static int queue_mode_select(struct scsi_device *sdev,
                activate_complete fn, void *data)
{
    struct rdac_queue_data *qdata;
    struct rdac_controller *ctlr;

    qdata = kzalloc(sizeof(*qdata), GFP_KERNEL);
    if (!qdata)
        return SCSI_DH_RETRY;

    qdata->h = get_rdac_data(sdev);
    qdata->callback_fn = fn;
    qdata->callback_data = data;

    ctlr = qdata->h->ctlr;
    spin_lock(&ctlr->ms_lock);
    list_add_tail(&qdata->entry, &ctlr->ms_head);
    if (!ctlr->ms_queued) {
        ctlr->ms_queued = 1;
        ctlr->ms_sdev = sdev;
        queue_work(kmpath_rdacd, &ctlr->ms_work);
    }
    spin_unlock(&ctlr->ms_lock);
    return SCSI_DH_OK;
}

static int rdac_activate(struct scsi_device *sdev,
            activate_complete fn, void *data)
{
    struct rdac_dh_data *h = get_rdac_data(sdev);
    int err = SCSI_DH_OK;
    int act = 0;

    err = check_ownership(sdev, h);
    if (err != SCSI_DH_OK)
        goto done;

    switch (h->mode) {
    case RDAC_MODE:
        if (h->lun_state == RDAC_LUN_UNOWNED)
            act = 1;
        break;
    case RDAC_MODE_IOSHIP:
        if ((h->lun_state == RDAC_LUN_UNOWNED) &&
            (h->preferred == RDAC_PREFERRED))
            act = 1;
        break;
    default:
        break;
    }

    if (act) {
        err = queue_mode_select(sdev, fn, data);
        if (err == SCSI_DH_OK)
            return 0;
    }
done:
    if (fn)
        fn(data, err);
    return 0;
}

static int rdac_prep_fn(struct scsi_device *sdev, struct request *req)
{
    struct rdac_dh_data *h = get_rdac_data(sdev);
    int ret = BLKPREP_OK;

    if (h->state != RDAC_STATE_ACTIVE) {
        ret = BLKPREP_KILL;
        req->cmd_flags |= REQ_QUIET;
    }
    return ret;

}

static int rdac_check_sense(struct scsi_device *sdev,
                struct scsi_sense_hdr *sense_hdr)
{
    struct rdac_dh_data *h = get_rdac_data(sdev);

    RDAC_LOG(RDAC_LOG_SENSE, sdev, "array %s, ctlr %d, "
            "I/O returned with sense %02x/%02x/%02x",
            (char *) h->ctlr->array_name, h->ctlr->index,
            sense_hdr->sense_key, sense_hdr->asc, sense_hdr->ascq);

    switch (sense_hdr->sense_key) {
    case NOT_READY:
        if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x01)
            /* LUN Not Ready - Logical Unit Not Ready and is in
            * the process of becoming ready
            * Just retry.
            */
            return ADD_TO_MLQUEUE;
        if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x81)
            /* LUN Not Ready - Storage firmware incompatible
             * Manual code synchonisation required.
             *
             * Nothing we can do here. Try to bypass the path.
             */
            return SUCCESS;
        if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0xA1)
            /* LUN Not Ready - Quiescense in progress
             *
             * Just retry and wait.
             */
            return ADD_TO_MLQUEUE;
        if (sense_hdr->asc == 0xA1  && sense_hdr->ascq == 0x02)
            /* LUN Not Ready - Quiescense in progress
             * or has been achieved
             * Just retry.
             */
            return ADD_TO_MLQUEUE;
        break;
    case ILLEGAL_REQUEST:
        if (sense_hdr->asc == 0x94 && sense_hdr->ascq == 0x01) {
            /* Invalid Request - Current Logical Unit Ownership.
             * Controller is not the current owner of the LUN,
             * Fail the path, so that the other path be used.
             */
            h->state = RDAC_STATE_PASSIVE;
            return SUCCESS;
        }
        break;
    case UNIT_ATTENTION:
        if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00)
            /*
             * Power On, Reset, or Bus Device Reset, just retry.
             */
            return ADD_TO_MLQUEUE;
        if (sense_hdr->asc == 0x8b && sense_hdr->ascq == 0x02)
            /*
             * Quiescence in progress , just retry.
             */
            return ADD_TO_MLQUEUE;
        break;
    }
    /* success just means we do not care what scsi-ml does */
    return SCSI_RETURN_NOT_HANDLED;
}

static const struct scsi_dh_devlist rdac_dev_list[] = {
    {"IBM", "1722"},
    {"IBM", "1724"},
    {"IBM", "1726"},
    {"IBM", "1742"},
    {"IBM", "1745"},
    {"IBM", "1746"},
    {"IBM", "1814"},
    {"IBM", "1815"},
    {"IBM", "1818"},
    {"IBM", "3526"},
    {"SGI", "TP9"},
    {"SGI", "IS"},
    {"STK", "OPENstorage D280"},
    {"STK", "FLEXLINE 380"},
    {"SUN", "CSM"},
    {"SUN", "LCSM100"},
    {"SUN", "STK6580_6780"},
    {"SUN", "SUN_6180"},
    {"SUN", "ArrayStorage"},
    {"DELL", "MD3"},
    {"NETAPP", "INF-01-00"},
    {"LSI", "INF-01-00"},
    {"ENGENIO", "INF-01-00"},
    {NULL, NULL},
};

static bool rdac_match(struct scsi_device *sdev)
{
    int i;

    if (scsi_device_tpgs(sdev))
        return false;

    for (i = 0; rdac_dev_list[i].vendor; i++) {
        if (!strncmp(sdev->vendor, rdac_dev_list[i].vendor,
            strlen(rdac_dev_list[i].vendor)) &&
            !strncmp(sdev->model, rdac_dev_list[i].model,
            strlen(rdac_dev_list[i].model))) {
            return true;
        }
    }
    return false;
}

static int rdac_bus_attach(struct scsi_device *sdev);
static void rdac_bus_detach(struct scsi_device *sdev);

static struct scsi_device_handler rdac_dh = {
    .name = RDAC_NAME,
    .module = THIS_MODULE,
    .devlist = rdac_dev_list,
    .prep_fn = rdac_prep_fn,
    .check_sense = rdac_check_sense,
    .attach = rdac_bus_attach,
    .detach = rdac_bus_detach,
    .activate = rdac_activate,
    .match = rdac_match,
};

static int rdac_bus_attach(struct scsi_device *sdev)
{
    struct scsi_dh_data *scsi_dh_data;
    struct rdac_dh_data *h;
    unsigned long flags;
    int err;
    char array_name[ARRAY_LABEL_LEN];
    char array_id[UNIQUE_ID_LEN];

    scsi_dh_data = kzalloc(sizeof(*scsi_dh_data)
                   + sizeof(*h) , GFP_KERNEL);
    if (!scsi_dh_data) {
        sdev_printk(KERN_ERR, sdev, "%s: Attach failed\n",
                RDAC_NAME);
        return -ENOMEM;
    }

    scsi_dh_data->scsi_dh = &rdac_dh;
    h = (struct rdac_dh_data *) scsi_dh_data->buf;
    h->lun = UNINITIALIZED_LUN;
    h->state = RDAC_STATE_ACTIVE;

    err = get_lun_info(sdev, h, array_name, array_id);
    if (err != SCSI_DH_OK)
        goto failed;

    err = initialize_controller(sdev, h, array_name, array_id);
    if (err != SCSI_DH_OK)
        goto failed;

    err = check_ownership(sdev, h);
    if (err != SCSI_DH_OK)
        goto clean_ctlr;

    err = set_mode_select(sdev, h);
    if (err != SCSI_DH_OK)
        goto clean_ctlr;

    if (!try_module_get(THIS_MODULE))
        goto clean_ctlr;

    spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
    sdev->scsi_dh_data = scsi_dh_data;
    spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);

    sdev_printk(KERN_NOTICE, sdev,
            "%s: LUN %d (%s) (%s)\n",
            RDAC_NAME, h->lun, mode[(int)h->mode],
            lun_state[(int)h->lun_state]);

    return 0;

clean_ctlr:
    spin_lock(&list_lock);
    kref_put(&h->ctlr->kref, release_controller);
    spin_unlock(&list_lock);

failed:
    kfree(scsi_dh_data);
    sdev_printk(KERN_ERR, sdev, "%s: not attached\n",
            RDAC_NAME);
    return -EINVAL;
}

static void rdac_bus_detach( struct scsi_device *sdev )
{
    struct scsi_dh_data *scsi_dh_data;
    struct rdac_dh_data *h;
    unsigned long flags;

    scsi_dh_data = sdev->scsi_dh_data;
    h = (struct rdac_dh_data *) scsi_dh_data->buf;
    if (h->ctlr && h->ctlr->ms_queued)
        flush_workqueue(kmpath_rdacd);

    spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
    sdev->scsi_dh_data = NULL;
    spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);

    spin_lock(&list_lock);
    if (h->ctlr)
        kref_put(&h->ctlr->kref, release_controller);
    spin_unlock(&list_lock);
    kfree(scsi_dh_data);
    module_put(THIS_MODULE);
    sdev_printk(KERN_NOTICE, sdev, "%s: Detached\n", RDAC_NAME);
}



static int __init rdac_init(void)
{
    int r;

    r = scsi_register_device_handler(&rdac_dh);
    if (r != 0) {
        printk(KERN_ERR "Failed to register scsi device handler.");
        goto done;
    }

    /*
     * Create workqueue to handle mode selects for rdac
     */
    kmpath_rdacd = create_singlethread_workqueue("kmpath_rdacd");
    if (!kmpath_rdacd) {
        scsi_unregister_device_handler(&rdac_dh);
        printk(KERN_ERR "kmpath_rdacd creation failed.\n");

        r = -EINVAL;
    }
done:
    return r;
}

static void __exit rdac_exit(void)
{
    destroy_workqueue(kmpath_rdacd);
    scsi_unregister_device_handler(&rdac_dh);
}

module_init(rdac_init);
module_exit(rdac_exit);

MODULE_DESCRIPTION("Multipath LSI/Engenio/NetApp E-Series RDAC driver");
MODULE_AUTHOR("Mike Christie, Chandra Seetharaman");
MODULE_VERSION("01.00.0000.0000");
MODULE_LICENSE("GPL");