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dm-mpath-rdac.c

/*
 * Engenio/LSI RDAC DM HW 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_cmnd.h>
#include <scsi/scsi_eh.h>

#define DM_MSG_PREFIX "multipath rdac"

#include "dm.h"
#include "dm-hw-handler.h"

#define RDAC_DM_HWH_NAME "rdac"
#define RDAC_DM_HWH_VER "0.4"

/*
 * 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_ALL_LUNS       0x01
#define RDAC_MODE_TRANSFER_SPECIFIED_LUNS 0x02

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

#define RDAC_FAILOVER_TIMEOUT (60 * HZ)

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

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];
};

struct rdac_controller {
      u8                subsys_id[SUBSYS_ID_LEN];
      u8                slot_id[SLOT_ID_LEN];
      int               use_10_ms;
      struct kref       kref;
      struct list_head  node; /* list of all controllers */
      spinlock_t        lock;
      int               submitted;
      struct list_head  cmd_list; /* list of commands to be submitted */
      union             {
            struct rdac_pg_legacy legacy;
            struct rdac_pg_expanded expanded;
      } mode_select;
};
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[16];
      u8    array_user_label_len;
      u8    array_user_label[60];
      u8    lun[8];
};

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_handler {
      struct list_head  entry; /* list waiting to submit MODE SELECT */
      unsigned          timeout;
      struct rdac_controller  *ctlr;
#define UNINITIALIZED_LUN     (1 << 8)
      unsigned          lun;
      unsigned char           sense[SCSI_SENSE_BUFFERSIZE];
      struct dm_path          *path;
      struct work_struct      work;
#define     SEND_C2_INQUIRY         1
#define     SEND_C4_INQUIRY         2
#define     SEND_C8_INQUIRY         3
#define     SEND_C9_INQUIRY         4
#define     SEND_MODE_SELECT  5
      int               cmd_to_send;
      union             {
            struct c2_inquiry c2;
            struct c4_inquiry c4;
            struct c8_inquiry c8;
            struct c9_inquiry c9;
      } inq;
};

static LIST_HEAD(ctlr_list);
static DEFINE_SPINLOCK(list_lock);
static struct workqueue_struct *rdac_wkqd;

static inline int had_failures(struct request *req, int error)
{
      return (error || host_byte(req->errors) != DID_OK ||
                  msg_byte(req->errors) != COMMAND_COMPLETE);
}

static void rdac_resubmit_all(struct rdac_handler *h)
{
      struct rdac_controller *ctlr = h->ctlr;
      struct rdac_handler *tmp, *h1;

      spin_lock(&ctlr->lock);
      list_for_each_entry_safe(h1, tmp, &ctlr->cmd_list, entry) {
            h1->cmd_to_send = SEND_C9_INQUIRY;
            queue_work(rdac_wkqd, &h1->work);
            list_del(&h1->entry);
      }
      ctlr->submitted = 0;
      spin_unlock(&ctlr->lock);
}

static void mode_select_endio(struct request *req, int error)
{
      struct rdac_handler *h = req->end_io_data;
      struct scsi_sense_hdr sense_hdr;
      int sense = 0, fail = 0;

      if (had_failures(req, error)) {
            fail = 1;
            goto failed;
      }

      if (status_byte(req->errors) == CHECK_CONDITION) {
            scsi_normalize_sense(req->sense, SCSI_SENSE_BUFFERSIZE,
                        &sense_hdr);
            sense = (sense_hdr.sense_key << 16) | (sense_hdr.asc << 8) |
                        sense_hdr.ascq;
            /* If it is retryable failure, submit the c9 inquiry again */
            if (sense == 0x59136 || sense == 0x68b02 || sense == 0xb8b02 ||
                sense == 0x62900) {
                  /* 0x59136    - Command lock contention
                   * 0x[6b]8b02 - Quiesense in progress or achieved
                   * 0x62900    - Power On, Reset, or Bus Device Reset
                   */
                  h->cmd_to_send = SEND_C9_INQUIRY;
                  queue_work(rdac_wkqd, &h->work);
                  goto done;
            }
            if (sense)
                  DMINFO("MODE_SELECT failed on %s with sense 0x%x",
                                    h->path->dev->name, sense);
      }
failed:
      if (fail || sense)
            dm_pg_init_complete(h->path, MP_FAIL_PATH);
      else
            dm_pg_init_complete(h->path, 0);

done:
      rdac_resubmit_all(h);
      __blk_put_request(req->q, req);
}

static struct request *get_rdac_req(struct rdac_handler *h,
                  void *buffer, unsigned buflen, int rw)
{
      struct request *rq;
      struct request_queue *q = bdev_get_queue(h->path->dev->bdev);

      rq = blk_get_request(q, rw, GFP_KERNEL);

      if (!rq) {
            DMINFO("get_rdac_req: blk_get_request failed");
            return NULL;
      }

      if (buflen && blk_rq_map_kern(q, rq, buffer, buflen, GFP_KERNEL)) {
            blk_put_request(rq);
            DMINFO("get_rdac_req: blk_rq_map_kern failed");
            return NULL;
      }

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

      rq->end_io_data = h;
      rq->timeout = h->timeout;
      rq->cmd_type = REQ_TYPE_BLOCK_PC;
      rq->cmd_flags |= REQ_FAILFAST | REQ_NOMERGE;
      return rq;
}

static struct request *rdac_failover_get(struct rdac_handler *h)
{
      struct request *rq;
      struct rdac_mode_common *common;
      unsigned data_size;

      if (h->ctlr->use_10_ms) {
            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;
            rdac_pg->lun_table[h->lun] = 0x81;
      } 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;
            rdac_pg->lun_table[h->lun] = 0x81;
      }
      common->rdac_mode[1] = RDAC_MODE_TRANSFER_SPECIFIED_LUNS;
      common->quiescence_timeout = RDAC_QUIESCENCE_TIME;
      common->rdac_options = RDAC_FORCED_QUIESENCE;

      /* get request for block layer packet command */
      rq = get_rdac_req(h, &h->ctlr->mode_select, data_size, WRITE);
      if (!rq) {
            DMERR("rdac_failover_get: no rq");
            return NULL;
      }

      /* Prepare the command. */
      if (h->ctlr->use_10_ms) {
            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]);

      return rq;
}

/* Acquires h->ctlr->lock */
static void submit_mode_select(struct rdac_handler *h)
{
      struct request *rq;
      struct request_queue *q = bdev_get_queue(h->path->dev->bdev);

      spin_lock(&h->ctlr->lock);
      if (h->ctlr->submitted) {
            list_add(&h->entry, &h->ctlr->cmd_list);
            goto drop_lock;
      }

      if (!q) {
            DMINFO("submit_mode_select: no queue");
            goto fail_path;
      }

      rq = rdac_failover_get(h);
      if (!rq) {
            DMERR("submit_mode_select: no rq");
            goto fail_path;
      }

      DMINFO("queueing MODE_SELECT command on %s", h->path->dev->name);

      blk_execute_rq_nowait(q, NULL, rq, 1, mode_select_endio);
      h->ctlr->submitted = 1;
      goto drop_lock;
fail_path:
      dm_pg_init_complete(h->path, MP_FAIL_PATH);
drop_lock:
      spin_unlock(&h->ctlr->lock);
}

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

      spin_lock(&list_lock);
      list_del(&ctlr->node);
      spin_unlock(&list_lock);
      kfree(ctlr);
}

static struct rdac_controller *get_controller(u8 *subsys_id, u8 *slot_id)
{
      struct rdac_controller *ctlr, *tmp;

      spin_lock(&list_lock);

      list_for_each_entry(tmp, &ctlr_list, node) {
            if ((memcmp(tmp->subsys_id, subsys_id, SUBSYS_ID_LEN) == 0) &&
                    (memcmp(tmp->slot_id, slot_id, SLOT_ID_LEN) == 0)) {
                  kref_get(&tmp->kref);
                  spin_unlock(&list_lock);
                  return tmp;
            }
      }
      ctlr = kmalloc(sizeof(*ctlr), GFP_ATOMIC);
      if (!ctlr)
            goto done;

      /* initialize fields of controller */
      memcpy(ctlr->subsys_id, subsys_id, SUBSYS_ID_LEN);
      memcpy(ctlr->slot_id, slot_id, SLOT_ID_LEN);
      kref_init(&ctlr->kref);
      spin_lock_init(&ctlr->lock);
      ctlr->submitted = 0;
      ctlr->use_10_ms = -1;
      INIT_LIST_HEAD(&ctlr->cmd_list);
      list_add(&ctlr->node, &ctlr_list);
done:
      spin_unlock(&list_lock);
      return ctlr;
}

static void c4_endio(struct request *req, int error)
{
      struct rdac_handler *h = req->end_io_data;
      struct c4_inquiry *sp;

      if (had_failures(req, error)) {
            dm_pg_init_complete(h->path, MP_FAIL_PATH);
            goto done;
      }

      sp = &h->inq.c4;

      h->ctlr = get_controller(sp->subsys_id, sp->slot_id);

      if (h->ctlr) {
            h->cmd_to_send = SEND_C9_INQUIRY;
            queue_work(rdac_wkqd, &h->work);
      } else
            dm_pg_init_complete(h->path, MP_FAIL_PATH);
done:
      __blk_put_request(req->q, req);
}

static void c2_endio(struct request *req, int error)
{
      struct rdac_handler *h = req->end_io_data;
      struct c2_inquiry *sp;

      if (had_failures(req, error)) {
            dm_pg_init_complete(h->path, MP_FAIL_PATH);
            goto done;
      }

      sp = &h->inq.c2;

      /* If more than MODE6_MAX_LUN luns are supported, use mode select 10 */
      if (sp->max_lun_supported >= MODE6_MAX_LUN)
            h->ctlr->use_10_ms = 1;
      else
            h->ctlr->use_10_ms = 0;

      h->cmd_to_send = SEND_MODE_SELECT;
      queue_work(rdac_wkqd, &h->work);
done:
      __blk_put_request(req->q, req);
}

static void c9_endio(struct request *req, int error)
{
      struct rdac_handler *h = req->end_io_data;
      struct c9_inquiry *sp;

      if (had_failures(req, error)) {
            dm_pg_init_complete(h->path, MP_FAIL_PATH);
            goto done;
      }

      /* We need to look at the sense keys here to take clear action.
       * For now simple logic: If the host is in AVT mode or if controller
       * owns the lun, return dm_pg_init_complete(), otherwise submit
       * MODE SELECT.
       */
      sp = &h->inq.c9;

      /* If in AVT mode, return success */
      if ((sp->avte_cvp >> 7) == 0x1) {
            dm_pg_init_complete(h->path, 0);
            goto done;
      }

      /* If the controller on this path owns the LUN, return success */
      if (sp->avte_cvp & 0x1) {
            dm_pg_init_complete(h->path, 0);
            goto done;
      }

      if (h->ctlr) {
            if (h->ctlr->use_10_ms == -1)
                  h->cmd_to_send = SEND_C2_INQUIRY;
            else
                  h->cmd_to_send = SEND_MODE_SELECT;
      } else
            h->cmd_to_send = SEND_C4_INQUIRY;
      queue_work(rdac_wkqd, &h->work);
done:
      __blk_put_request(req->q, req);
}

static void c8_endio(struct request *req, int error)
{
      struct rdac_handler *h = req->end_io_data;
      struct c8_inquiry *sp;

      if (had_failures(req, error)) {
            dm_pg_init_complete(h->path, MP_FAIL_PATH);
            goto done;
      }

      /* We need to look at the sense keys here to take clear action.
       * For now simple logic: Get the lun from the inquiry page.
       */
      sp = &h->inq.c8;
      h->lun = sp->lun[7]; /* currently it uses only one byte */
      h->cmd_to_send = SEND_C9_INQUIRY;
      queue_work(rdac_wkqd, &h->work);
done:
      __blk_put_request(req->q, req);
}

static void submit_inquiry(struct rdac_handler *h, int page_code,
            unsigned int len, rq_end_io_fn endio)
{
      struct request *rq;
      struct request_queue *q = bdev_get_queue(h->path->dev->bdev);

      if (!q)
            goto fail_path;

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

      /* 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);
      blk_execute_rq_nowait(q, NULL, rq, 1, endio);
      return;

fail_path:
      dm_pg_init_complete(h->path, MP_FAIL_PATH);
}

static void service_wkq(struct work_struct *work)
{
      struct rdac_handler *h = container_of(work, struct rdac_handler, work);

      switch (h->cmd_to_send) {
      case SEND_C2_INQUIRY:
            submit_inquiry(h, 0xC2, sizeof(struct c2_inquiry), c2_endio);
            break;
      case SEND_C4_INQUIRY:
            submit_inquiry(h, 0xC4, sizeof(struct c4_inquiry), c4_endio);
            break;
      case SEND_C8_INQUIRY:
            submit_inquiry(h, 0xC8, sizeof(struct c8_inquiry), c8_endio);
            break;
      case SEND_C9_INQUIRY:
            submit_inquiry(h, 0xC9, sizeof(struct c9_inquiry), c9_endio);
            break;
      case SEND_MODE_SELECT:
            submit_mode_select(h);
            break;
      default:
            BUG();
      }
}
/*
 * only support subpage2c until we confirm that this is just a matter of
 * of updating firmware or not, and RDAC (basic AVT works already) for now
 * but we can add these in in when we get time and testers
 */
static int rdac_create(struct hw_handler *hwh, unsigned argc, char **argv)
{
      struct rdac_handler *h;
      unsigned timeout;

      if (argc == 0) {
            /* No arguments: use defaults */
            timeout = RDAC_FAILOVER_TIMEOUT;
      } else if (argc != 1) {
            DMWARN("incorrect number of arguments");
            return -EINVAL;
      } else {
            if (sscanf(argv[1], "%u", &timeout) != 1) {
                  DMWARN("invalid timeout value");
                  return -EINVAL;
            }
      }

      h = kzalloc(sizeof(*h), GFP_KERNEL);
      if (!h)
            return -ENOMEM;

      hwh->context = h;
      h->timeout = timeout;
      h->lun = UNINITIALIZED_LUN;
      INIT_WORK(&h->work, service_wkq);
      DMWARN("using RDAC command with timeout %u", h->timeout);

      return 0;
}

static void rdac_destroy(struct hw_handler *hwh)
{
      struct rdac_handler *h = hwh->context;

      if (h->ctlr)
            kref_put(&h->ctlr->kref, release_ctlr);
      kfree(h);
      hwh->context = NULL;
}

static unsigned rdac_error(struct hw_handler *hwh, struct bio *bio)
{
      /* Try default handler */
      return dm_scsi_err_handler(hwh, bio);
}

static void rdac_pg_init(struct hw_handler *hwh, unsigned bypassed,
                  struct dm_path *path)
{
      struct rdac_handler *h = hwh->context;

      h->path = path;
      switch (h->lun) {
      case UNINITIALIZED_LUN:
            submit_inquiry(h, 0xC8, sizeof(struct c8_inquiry), c8_endio);
            break;
      default:
            submit_inquiry(h, 0xC9, sizeof(struct c9_inquiry), c9_endio);
      }
}

static struct hw_handler_type rdac_handler = {
      .name = RDAC_DM_HWH_NAME,
      .module = THIS_MODULE,
      .create = rdac_create,
      .destroy = rdac_destroy,
      .pg_init = rdac_pg_init,
      .error = rdac_error,
};

static int __init rdac_init(void)
{
      int r;

      rdac_wkqd = create_singlethread_workqueue("rdac_wkqd");
      if (!rdac_wkqd) {
            DMERR("Failed to create workqueue rdac_wkqd.");
            return -ENOMEM;
      }

      r = dm_register_hw_handler(&rdac_handler);
      if (r < 0) {
            DMERR("%s: register failed %d", RDAC_DM_HWH_NAME, r);
            destroy_workqueue(rdac_wkqd);
            return r;
      }

      DMINFO("%s: version %s loaded", RDAC_DM_HWH_NAME, RDAC_DM_HWH_VER);
      return 0;
}

static void __exit rdac_exit(void)
{
      int r = dm_unregister_hw_handler(&rdac_handler);

      destroy_workqueue(rdac_wkqd);
      if (r < 0)
            DMERR("%s: unregister failed %d", RDAC_DM_HWH_NAME, r);
}

module_init(rdac_init);
module_exit(rdac_exit);

MODULE_DESCRIPTION("DM Multipath LSI/Engenio RDAC support");
MODULE_AUTHOR("Mike Christie, Chandra Seetharaman");
MODULE_LICENSE("GPL");
MODULE_VERSION(RDAC_DM_HWH_VER);

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