drivers/scsi/device_handler/scsi_dh_alua.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Generic SCSI-3 ALUA SCSI Device Handler
   4  *
   5  * Copyright (C) 2007-2010 Hannes Reinecke, SUSE Linux Products GmbH.
   6  * All rights reserved.
   7  */
   8 #include <linux/slab.h>
   9 #include <linux/delay.h>
  10 #include <linux/module.h>
  11 #include <asm/unaligned.h>
  12 #include <scsi/scsi.h>
  13 #include <scsi/scsi_proto.h>
  14 #include <scsi/scsi_dbg.h>
  15 #include <scsi/scsi_eh.h>
  16 #include <scsi/scsi_dh.h>
  17
  18 #define ALUA_DH_NAME "alua"
  19 #define ALUA_DH_VER "2.0"
  20
  21 #define TPGS_SUPPORT_NONE               0x00
  22 #define TPGS_SUPPORT_OPTIMIZED          0x01
  23 #define TPGS_SUPPORT_NONOPTIMIZED       0x02
  24 #define TPGS_SUPPORT_STANDBY            0x04
  25 #define TPGS_SUPPORT_UNAVAILABLE        0x08
  26 #define TPGS_SUPPORT_LBA_DEPENDENT      0x10
  27 #define TPGS_SUPPORT_OFFLINE            0x40
  28 #define TPGS_SUPPORT_TRANSITION         0x80
  29 #define TPGS_SUPPORT_ALL                0xdf
  30
  31 #define RTPG_FMT_MASK                   0x70
  32 #define RTPG_FMT_EXT_HDR                0x10
  33
  34 #define TPGS_MODE_UNINITIALIZED          -1
  35 #define TPGS_MODE_NONE                  0x0
  36 #define TPGS_MODE_IMPLICIT              0x1
  37 #define TPGS_MODE_EXPLICIT              0x2
  38
  39 #define ALUA_RTPG_SIZE                  128
  40 #define ALUA_FAILOVER_TIMEOUT           60
  41 #define ALUA_FAILOVER_RETRIES           5
  42 #define ALUA_RTPG_DELAY_MSECS           5
  43
  44 /* device handler flags */
  45 #define ALUA_OPTIMIZE_STPG              0x01
  46 #define ALUA_RTPG_EXT_HDR_UNSUPP        0x02
  47 /* State machine flags */
  48 #define ALUA_PG_RUN_RTPG                0x10
  49 #define ALUA_PG_RUN_STPG                0x20
  50 #define ALUA_PG_RUNNING                 0x40
  51
  52 static uint optimize_stpg;
  53 module_param(optimize_stpg, uint, S_IRUGO|S_IWUSR);
  54 MODULE_PARM_DESC(optimize_stpg, "Allow use of a non-optimized path, rather than sending a STPG, when implicit TPGS is supported (0=No,1=Yes). Default is 0.");
  55
  56 static LIST_HEAD(port_group_list);
  57 static DEFINE_SPINLOCK(port_group_lock);
  58 static struct workqueue_struct *kaluad_wq;
  59
  60 struct alua_port_group {
  61         struct kref             kref;
  62         struct rcu_head         rcu;
  63         struct list_head        node;
  64         struct list_head        dh_list;
  65         unsigned char           device_id_str[256];
  66         int                     device_id_len;
  67         int                     group_id;
  68         int                     tpgs;
  69         int                     state;
  70         int                     pref;
  71         int                     valid_states;
  72         unsigned                flags; /* used for optimizing STPG */
  73         unsigned char           transition_tmo;
  74         unsigned long           expiry;
  75         unsigned long           interval;
  76         struct delayed_work     rtpg_work;
  77         spinlock_t              lock;
  78         struct list_head        rtpg_list;
  79         struct scsi_device      *rtpg_sdev;
  80 };
  81
  82 struct alua_dh_data {
  83         struct list_head        node;
  84         struct alua_port_group __rcu *pg;
  85         int                     group_id;
  86         spinlock_t              pg_lock;
  87         struct scsi_device      *sdev;
  88         int                     init_error;
  89         struct mutex            init_mutex;
  90 };
  91
  92 struct alua_queue_data {
  93         struct list_head        entry;
  94         activate_complete       callback_fn;
  95         void                    *callback_data;
  96 };
  97
  98 #define ALUA_POLICY_SWITCH_CURRENT      0
  99 #define ALUA_POLICY_SWITCH_ALL          1
 100
 101 static void alua_rtpg_work(struct work_struct *work);
 102 static bool alua_rtpg_queue(struct alua_port_group *pg,
 103                             struct scsi_device *sdev,
 104                             struct alua_queue_data *qdata, bool force);
 105 static void alua_check(struct scsi_device *sdev, bool force);
 106
 107 static void release_port_group(struct kref *kref)
 108 {
 109         struct alua_port_group *pg;
 110
 111         pg = container_of(kref, struct alua_port_group, kref);
 112         if (pg->rtpg_sdev)
 113                 flush_delayed_work(&pg->rtpg_work);
 114         spin_lock(&port_group_lock);
 115         list_del(&pg->node);
 116         spin_unlock(&port_group_lock);
 117         kfree_rcu(pg, rcu);
 118 }
 119
 120 /*
 121  * submit_rtpg - Issue a REPORT TARGET GROUP STATES command
 122  * @sdev: sdev the command should be sent to
 123  */
 124 static int submit_rtpg(struct scsi_device *sdev, unsigned char *buff,
 125                        int bufflen, struct scsi_sense_hdr *sshdr, int flags)
 126 {
 127         u8 cdb[MAX_COMMAND_SIZE];
 128         int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
 129                 REQ_FAILFAST_DRIVER;
 130
 131         /* Prepare the command. */
 132         memset(cdb, 0x0, MAX_COMMAND_SIZE);
 133         cdb[0] = MAINTENANCE_IN;
 134         if (!(flags & ALUA_RTPG_EXT_HDR_UNSUPP))
 135                 cdb[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
 136         else
 137                 cdb[1] = MI_REPORT_TARGET_PGS;
 138         put_unaligned_be32(bufflen, &cdb[6]);
 139
 140         return scsi_execute(sdev, cdb, DMA_FROM_DEVICE, buff, bufflen, NULL,
 141                         sshdr, ALUA_FAILOVER_TIMEOUT * HZ,
 142                         ALUA_FAILOVER_RETRIES, req_flags, 0, NULL);
 143 }
 144
 145 /*
 146  * submit_stpg - Issue a SET TARGET PORT GROUP command
 147  *
 148  * Currently we're only setting the current target port group state
 149  * to 'active/optimized' and let the array firmware figure out
 150  * the states of the remaining groups.
 151  */
 152 static int submit_stpg(struct scsi_device *sdev, int group_id,
 153                        struct scsi_sense_hdr *sshdr)
 154 {
 155         u8 cdb[MAX_COMMAND_SIZE];
 156         unsigned char stpg_data[8];
 157         int stpg_len = 8;
 158         int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
 159                 REQ_FAILFAST_DRIVER;
 160
 161         /* Prepare the data buffer */
 162         memset(stpg_data, 0, stpg_len);
 163         stpg_data[4] = SCSI_ACCESS_STATE_OPTIMAL;
 164         put_unaligned_be16(group_id, &stpg_data[6]);
 165
 166         /* Prepare the command. */
 167         memset(cdb, 0x0, MAX_COMMAND_SIZE);
 168         cdb[0] = MAINTENANCE_OUT;
 169         cdb[1] = MO_SET_TARGET_PGS;
 170         put_unaligned_be32(stpg_len, &cdb[6]);
 171
 172         return scsi_execute(sdev, cdb, DMA_TO_DEVICE, stpg_data, stpg_len, NULL,
 173                         sshdr, ALUA_FAILOVER_TIMEOUT * HZ,
 174                         ALUA_FAILOVER_RETRIES, req_flags, 0, NULL);
 175 }
 176
 177 static struct alua_port_group *alua_find_get_pg(char *id_str, size_t id_size,
 178                                                 int group_id)
 179 {
 180         struct alua_port_group *pg;
 181
 182         if (!id_str || !id_size || !strlen(id_str))
 183                 return NULL;
 184
 185         list_for_each_entry(pg, &port_group_list, node) {
 186                 if (pg->group_id != group_id)
 187                         continue;
 188                 if (!pg->device_id_len || pg->device_id_len != id_size)
 189                         continue;
 190                 if (strncmp(pg->device_id_str, id_str, id_size))
 191                         continue;
 192                 if (!kref_get_unless_zero(&pg->kref))
 193                         continue;
 194                 return pg;
 195         }
 196
 197         return NULL;
 198 }
 199
 200 /*
 201  * alua_alloc_pg - Allocate a new port_group structure
 202  * @sdev: scsi device
 203  * @group_id: port group id
 204  * @tpgs: target port group settings
 205  *
 206  * Allocate a new port_group structure for a given
 207  * device.
 208  */
 209 static struct alua_port_group *alua_alloc_pg(struct scsi_device *sdev,
 210                                              int group_id, int tpgs)
 211 {
 212         struct alua_port_group *pg, *tmp_pg;
 213
 214         pg = kzalloc(sizeof(struct alua_port_group), GFP_KERNEL);
 215         if (!pg)
 216                 return ERR_PTR(-ENOMEM);
 217
 218         pg->device_id_len = scsi_vpd_lun_id(sdev, pg->device_id_str,
 219                                             sizeof(pg->device_id_str));
 220         if (pg->device_id_len <= 0) {
 221                 /*
 222                  * TPGS supported but no device identification found.
 223                  * Generate private device identification.
 224                  */
 225                 sdev_printk(KERN_INFO, sdev,
 226                             "%s: No device descriptors found\n",
 227                             ALUA_DH_NAME);
 228                 pg->device_id_str[0] = '\0';
 229                 pg->device_id_len = 0;
 230         }
 231         pg->group_id = group_id;
 232         pg->tpgs = tpgs;
 233         pg->state = SCSI_ACCESS_STATE_OPTIMAL;
 234         pg->valid_states = TPGS_SUPPORT_ALL;
 235         if (optimize_stpg)
 236                 pg->flags |= ALUA_OPTIMIZE_STPG;
 237         kref_init(&pg->kref);
 238         INIT_DELAYED_WORK(&pg->rtpg_work, alua_rtpg_work);
 239         INIT_LIST_HEAD(&pg->rtpg_list);
 240         INIT_LIST_HEAD(&pg->node);
 241         INIT_LIST_HEAD(&pg->dh_list);
 242         spin_lock_init(&pg->lock);
 243
 244         spin_lock(&port_group_lock);
 245         tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len,
 246                                   group_id);
 247         if (tmp_pg) {
 248                 spin_unlock(&port_group_lock);
 249                 kfree(pg);
 250                 return tmp_pg;
 251         }
 252
 253         list_add(&pg->node, &port_group_list);
 254         spin_unlock(&port_group_lock);
 255
 256         return pg;
 257 }
 258
 259 /*
 260  * alua_check_tpgs - Evaluate TPGS setting
 261  * @sdev: device to be checked
 262  *
 263  * Examine the TPGS setting of the sdev to find out if ALUA
 264  * is supported.
 265  */
 266 static int alua_check_tpgs(struct scsi_device *sdev)
 267 {
 268         int tpgs = TPGS_MODE_NONE;
 269
 270         /*
 271          * ALUA support for non-disk devices is fraught with
 272          * difficulties, so disable it for now.
 273          */
 274         if (sdev->type != TYPE_DISK) {
 275                 sdev_printk(KERN_INFO, sdev,
 276                             "%s: disable for non-disk devices\n",
 277                             ALUA_DH_NAME);
 278                 return tpgs;
 279         }
 280
 281         tpgs = scsi_device_tpgs(sdev);
 282         switch (tpgs) {
 283         case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT:
 284                 sdev_printk(KERN_INFO, sdev,
 285                             "%s: supports implicit and explicit TPGS\n",
 286                             ALUA_DH_NAME);
 287                 break;
 288         case TPGS_MODE_EXPLICIT:
 289                 sdev_printk(KERN_INFO, sdev, "%s: supports explicit TPGS\n",
 290                             ALUA_DH_NAME);
 291                 break;
 292         case TPGS_MODE_IMPLICIT:
 293                 sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n",
 294                             ALUA_DH_NAME);
 295                 break;
 296         case TPGS_MODE_NONE:
 297                 sdev_printk(KERN_INFO, sdev, "%s: not supported\n",
 298                             ALUA_DH_NAME);
 299                 break;
 300         default:
 301                 sdev_printk(KERN_INFO, sdev,
 302                             "%s: unsupported TPGS setting %d\n",
 303                             ALUA_DH_NAME, tpgs);
 304                 tpgs = TPGS_MODE_NONE;
 305                 break;
 306         }
 307
 308         return tpgs;
 309 }
 310
 311 /*
 312  * alua_check_vpd - Evaluate INQUIRY vpd page 0x83
 313  * @sdev: device to be checked
 314  *
 315  * Extract the relative target port and the target port group
 316  * descriptor from the list of identificators.
 317  */
 318 static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h,
 319                           int tpgs)
 320 {
 321         int rel_port = -1, group_id;
 322         struct alua_port_group *pg, *old_pg = NULL;
 323         bool pg_updated = false;
 324         unsigned long flags;
 325
 326         group_id = scsi_vpd_tpg_id(sdev, &rel_port);
 327         if (group_id < 0) {
 328                 /*
 329                  * Internal error; TPGS supported but required
 330                  * VPD identification descriptors not present.
 331                  * Disable ALUA support
 332                  */
 333                 sdev_printk(KERN_INFO, sdev,
 334                             "%s: No target port descriptors found\n",
 335                             ALUA_DH_NAME);
 336                 return SCSI_DH_DEV_UNSUPP;
 337         }
 338
 339         pg = alua_alloc_pg(sdev, group_id, tpgs);
 340         if (IS_ERR(pg)) {
 341                 if (PTR_ERR(pg) == -ENOMEM)
 342                         return SCSI_DH_NOMEM;
 343                 return SCSI_DH_DEV_UNSUPP;
 344         }
 345         if (pg->device_id_len)
 346                 sdev_printk(KERN_INFO, sdev,
 347                             "%s: device %s port group %x rel port %x\n",
 348                             ALUA_DH_NAME, pg->device_id_str,
 349                             group_id, rel_port);
 350         else
 351                 sdev_printk(KERN_INFO, sdev,
 352                             "%s: port group %x rel port %x\n",
 353                             ALUA_DH_NAME, group_id, rel_port);
 354
 355         /* Check for existing port group references */
 356         spin_lock(&h->pg_lock);
 357         old_pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock));
 358         if (old_pg != pg) {
 359                 /* port group has changed. Update to new port group */
 360                 if (h->pg) {
 361                         spin_lock_irqsave(&old_pg->lock, flags);
 362                         list_del_rcu(&h->node);
 363                         spin_unlock_irqrestore(&old_pg->lock, flags);
 364                 }
 365                 rcu_assign_pointer(h->pg, pg);
 366                 pg_updated = true;
 367         }
 368
 369         spin_lock_irqsave(&pg->lock, flags);
 370         if (pg_updated)
 371                 list_add_rcu(&h->node, &pg->dh_list);
 372         spin_unlock_irqrestore(&pg->lock, flags);
 373
 374         alua_rtpg_queue(rcu_dereference_protected(h->pg,
 375                                                   lockdep_is_held(&h->pg_lock)),
 376                         sdev, NULL, true);
 377         spin_unlock(&h->pg_lock);
 378
 379         if (old_pg)
 380                 kref_put(&old_pg->kref, release_port_group);
 381
 382         return SCSI_DH_OK;
 383 }
 384
 385 static char print_alua_state(unsigned char state)
 386 {
 387         switch (state) {
 388         case SCSI_ACCESS_STATE_OPTIMAL:
 389                 return 'A';
 390         case SCSI_ACCESS_STATE_ACTIVE:
 391                 return 'N';
 392         case SCSI_ACCESS_STATE_STANDBY:
 393                 return 'S';
 394         case SCSI_ACCESS_STATE_UNAVAILABLE:
 395                 return 'U';
 396         case SCSI_ACCESS_STATE_LBA:
 397                 return 'L';
 398         case SCSI_ACCESS_STATE_OFFLINE:
 399                 return 'O';
 400         case SCSI_ACCESS_STATE_TRANSITIONING:
 401                 return 'T';
 402         default:
 403                 return 'X';
 404         }
 405 }
 406
 407 static int alua_check_sense(struct scsi_device *sdev,
 408                             struct scsi_sense_hdr *sense_hdr)
 409 {
 410         switch (sense_hdr->sense_key) {
 411         case NOT_READY:
 412                 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) {
 413                         /*
 414                          * LUN Not Accessible - ALUA state transition
 415                          */
 416                         alua_check(sdev, false);
 417                         return NEEDS_RETRY;
 418                 }
 419                 break;
 420         case UNIT_ATTENTION:
 421                 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) {
 422                         /*
 423                          * Power On, Reset, or Bus Device Reset.
 424                          * Might have obscured a state transition,
 425                          * so schedule a recheck.
 426                          */
 427                         alua_check(sdev, true);
 428                         return ADD_TO_MLQUEUE;
 429                 }
 430                 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04)
 431                         /*
 432                          * Device internal reset
 433                          */
 434                         return ADD_TO_MLQUEUE;
 435                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01)
 436                         /*
 437                          * Mode Parameters Changed
 438                          */
 439                         return ADD_TO_MLQUEUE;
 440                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06) {
 441                         /*
 442                          * ALUA state changed
 443                          */
 444                         alua_check(sdev, true);
 445                         return ADD_TO_MLQUEUE;
 446                 }
 447                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07) {
 448                         /*
 449                          * Implicit ALUA state transition failed
 450                          */
 451                         alua_check(sdev, true);
 452                         return ADD_TO_MLQUEUE;
 453                 }
 454                 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03)
 455                         /*
 456                          * Inquiry data has changed
 457                          */
 458                         return ADD_TO_MLQUEUE;
 459                 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x0e)
 460                         /*
 461                          * REPORTED_LUNS_DATA_HAS_CHANGED is reported
 462                          * when switching controllers on targets like
 463                          * Intel Multi-Flex. We can just retry.
 464                          */
 465                         return ADD_TO_MLQUEUE;
 466                 break;
 467         }
 468
 469         return SCSI_RETURN_NOT_HANDLED;
 470 }
 471
 472 /*
 473  * alua_tur - Send a TEST UNIT READY
 474  * @sdev: device to which the TEST UNIT READY command should be send
 475  *
 476  * Send a TEST UNIT READY to @sdev to figure out the device state
 477  * Returns SCSI_DH_RETRY if the sense code is NOT READY/ALUA TRANSITIONING,
 478  * SCSI_DH_OK if no error occurred, and SCSI_DH_IO otherwise.
 479  */
 480 static int alua_tur(struct scsi_device *sdev)
 481 {
 482         struct scsi_sense_hdr sense_hdr;
 483         int retval;
 484
 485         retval = scsi_test_unit_ready(sdev, ALUA_FAILOVER_TIMEOUT * HZ,
 486                                       ALUA_FAILOVER_RETRIES, &sense_hdr);
 487         if (sense_hdr.sense_key == NOT_READY &&
 488             sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a)
 489                 return SCSI_DH_RETRY;
 490         else if (retval)
 491                 return SCSI_DH_IO;
 492         else
 493                 return SCSI_DH_OK;
 494 }
 495
 496 /*
 497  * alua_rtpg - Evaluate REPORT TARGET GROUP STATES
 498  * @sdev: the device to be evaluated.
 499  *
 500  * Evaluate the Target Port Group State.
 501  * Returns SCSI_DH_DEV_OFFLINED if the path is
 502  * found to be unusable.
 503  */
 504 static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
 505 {
 506         struct scsi_sense_hdr sense_hdr;
 507         struct alua_port_group *tmp_pg;
 508         int len, k, off, bufflen = ALUA_RTPG_SIZE;
 509         unsigned char *desc, *buff;
 510         unsigned err, retval;
 511         unsigned int tpg_desc_tbl_off;
 512         unsigned char orig_transition_tmo;
 513         unsigned long flags;
 514
 515         if (!pg->expiry) {
 516                 unsigned long transition_tmo = ALUA_FAILOVER_TIMEOUT * HZ;
 517
 518                 if (pg->transition_tmo)
 519                         transition_tmo = pg->transition_tmo * HZ;
 520
 521                 pg->expiry = round_jiffies_up(jiffies + transition_tmo);
 522         }
 523
 524         buff = kzalloc(bufflen, GFP_KERNEL);
 525         if (!buff)
 526                 return SCSI_DH_DEV_TEMP_BUSY;
 527
 528  retry:
 529         err = 0;
 530         retval = submit_rtpg(sdev, buff, bufflen, &sense_hdr, pg->flags);
 531
 532         if (retval) {
 533                 /*
 534                  * Some (broken) implementations have a habit of returning
 535                  * an error during things like firmware update etc.
 536                  * But if the target only supports active/optimized there's
 537                  * not much we can do; it's not that we can switch paths
 538                  * or anything.
 539                  * So ignore any errors to avoid spurious failures during
 540                  * path failover.
 541                  */
 542                 if ((pg->valid_states & ~TPGS_SUPPORT_OPTIMIZED) == 0) {
 543                         sdev_printk(KERN_INFO, sdev,
 544                                     "%s: ignoring rtpg result %d\n",
 545                                     ALUA_DH_NAME, retval);
 546                         kfree(buff);
 547                         return SCSI_DH_OK;
 548                 }
 549                 if (!scsi_sense_valid(&sense_hdr)) {
 550                         sdev_printk(KERN_INFO, sdev,
 551                                     "%s: rtpg failed, result %d\n",
 552                                     ALUA_DH_NAME, retval);
 553                         kfree(buff);
 554                         if (driver_byte(retval) == DRIVER_ERROR)
 555                                 return SCSI_DH_DEV_TEMP_BUSY;
 556                         return SCSI_DH_IO;
 557                 }
 558
 559                 /*
 560                  * submit_rtpg() has failed on existing arrays
 561                  * when requesting extended header info, and
 562                  * the array doesn't support extended headers,
 563                  * even though it shouldn't according to T10.
 564                  * The retry without rtpg_ext_hdr_req set
 565                  * handles this.
 566                  */
 567                 if (!(pg->flags & ALUA_RTPG_EXT_HDR_UNSUPP) &&
 568                     sense_hdr.sense_key == ILLEGAL_REQUEST &&
 569                     sense_hdr.asc == 0x24 && sense_hdr.ascq == 0) {
 570                         pg->flags |= ALUA_RTPG_EXT_HDR_UNSUPP;
 571                         goto retry;
 572                 }
 573                 /*
 574                  * Retry on ALUA state transition or if any
 575                  * UNIT ATTENTION occurred.
 576                  */
 577                 if (sense_hdr.sense_key == NOT_READY &&
 578                     sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a)
 579                         err = SCSI_DH_RETRY;
 580                 else if (sense_hdr.sense_key == UNIT_ATTENTION)
 581                         err = SCSI_DH_RETRY;
 582                 if (err == SCSI_DH_RETRY &&
 583                     pg->expiry != 0 && time_before(jiffies, pg->expiry)) {
 584                         sdev_printk(KERN_ERR, sdev, "%s: rtpg retry\n",
 585                                     ALUA_DH_NAME);
 586                         scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 587                         kfree(buff);
 588                         return err;
 589                 }
 590                 sdev_printk(KERN_ERR, sdev, "%s: rtpg failed\n",
 591                             ALUA_DH_NAME);
 592                 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 593                 kfree(buff);
 594                 pg->expiry = 0;
 595                 return SCSI_DH_IO;
 596         }
 597
 598         len = get_unaligned_be32(&buff[0]) + 4;
 599
 600         if (len > bufflen) {
 601                 /* Resubmit with the correct length */
 602                 kfree(buff);
 603                 bufflen = len;
 604                 buff = kmalloc(bufflen, GFP_KERNEL);
 605                 if (!buff) {
 606                         sdev_printk(KERN_WARNING, sdev,
 607                                     "%s: kmalloc buffer failed\n",__func__);
 608                         /* Temporary failure, bypass */
 609                         pg->expiry = 0;
 610                         return SCSI_DH_DEV_TEMP_BUSY;
 611                 }
 612                 goto retry;
 613         }
 614
 615         orig_transition_tmo = pg->transition_tmo;
 616         if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR && buff[5] != 0)
 617                 pg->transition_tmo = buff[5];
 618         else
 619                 pg->transition_tmo = ALUA_FAILOVER_TIMEOUT;
 620
 621         if (orig_transition_tmo != pg->transition_tmo) {
 622                 sdev_printk(KERN_INFO, sdev,
 623                             "%s: transition timeout set to %d seconds\n",
 624                             ALUA_DH_NAME, pg->transition_tmo);
 625                 pg->expiry = jiffies + pg->transition_tmo * HZ;
 626         }
 627
 628         if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR)
 629                 tpg_desc_tbl_off = 8;
 630         else
 631                 tpg_desc_tbl_off = 4;
 632
 633         for (k = tpg_desc_tbl_off, desc = buff + tpg_desc_tbl_off;
 634              k < len;
 635              k += off, desc += off) {
 636                 u16 group_id = get_unaligned_be16(&desc[2]);
 637
 638                 spin_lock_irqsave(&port_group_lock, flags);
 639                 tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len,
 640                                           group_id);
 641                 spin_unlock_irqrestore(&port_group_lock, flags);
 642                 if (tmp_pg) {
 643                         if (spin_trylock_irqsave(&tmp_pg->lock, flags)) {
 644                                 if ((tmp_pg == pg) ||
 645                                     !(tmp_pg->flags & ALUA_PG_RUNNING)) {
 646                                         struct alua_dh_data *h;
 647
 648                                         tmp_pg->state = desc[0] & 0x0f;
 649                                         tmp_pg->pref = desc[0] >> 7;
 650                                         rcu_read_lock();
 651                                         list_for_each_entry_rcu(h,
 652                                                 &tmp_pg->dh_list, node) {
 653                                                 /* h->sdev should always be valid */
 654                                                 BUG_ON(!h->sdev);
 655                                                 h->sdev->access_state = desc[0];
 656                                         }
 657                                         rcu_read_unlock();
 658                                 }
 659                                 if (tmp_pg == pg)
 660                                         tmp_pg->valid_states = desc[1];
 661                                 spin_unlock_irqrestore(&tmp_pg->lock, flags);
 662                         }
 663                         kref_put(&tmp_pg->kref, release_port_group);
 664                 }
 665                 off = 8 + (desc[7] * 4);
 666         }
 667
 668         spin_lock_irqsave(&pg->lock, flags);
 669         sdev_printk(KERN_INFO, sdev,
 670                     "%s: port group %02x state %c %s supports %c%c%c%c%c%c%c\n",
 671                     ALUA_DH_NAME, pg->group_id, print_alua_state(pg->state),
 672                     pg->pref ? "preferred" : "non-preferred",
 673                     pg->valid_states&TPGS_SUPPORT_TRANSITION?'T':'t',
 674                     pg->valid_states&TPGS_SUPPORT_OFFLINE?'O':'o',
 675                     pg->valid_states&TPGS_SUPPORT_LBA_DEPENDENT?'L':'l',
 676                     pg->valid_states&TPGS_SUPPORT_UNAVAILABLE?'U':'u',
 677                     pg->valid_states&TPGS_SUPPORT_STANDBY?'S':'s',
 678                     pg->valid_states&TPGS_SUPPORT_NONOPTIMIZED?'N':'n',
 679                     pg->valid_states&TPGS_SUPPORT_OPTIMIZED?'A':'a');
 680
 681         switch (pg->state) {
 682         case SCSI_ACCESS_STATE_TRANSITIONING:
 683                 if (time_before(jiffies, pg->expiry)) {
 684                         /* State transition, retry */
 685                         pg->interval = 2;
 686                         err = SCSI_DH_RETRY;
 687                 } else {
 688                         struct alua_dh_data *h;
 689
 690                         /* Transitioning time exceeded, set port to standby */
 691                         err = SCSI_DH_IO;
 692                         pg->state = SCSI_ACCESS_STATE_STANDBY;
 693                         pg->expiry = 0;
 694                         rcu_read_lock();
 695                         list_for_each_entry_rcu(h, &pg->dh_list, node) {
 696                                 BUG_ON(!h->sdev);
 697                                 h->sdev->access_state =
 698                                         (pg->state & SCSI_ACCESS_STATE_MASK);
 699                                 if (pg->pref)
 700                                         h->sdev->access_state |=
 701                                                 SCSI_ACCESS_STATE_PREFERRED;
 702                         }
 703                         rcu_read_unlock();
 704                 }
 705                 break;
 706         case SCSI_ACCESS_STATE_OFFLINE:
 707                 /* Path unusable */
 708                 err = SCSI_DH_DEV_OFFLINED;
 709                 pg->expiry = 0;
 710                 break;
 711         default:
 712                 /* Useable path if active */
 713                 err = SCSI_DH_OK;
 714                 pg->expiry = 0;
 715                 break;
 716         }
 717         spin_unlock_irqrestore(&pg->lock, flags);
 718         kfree(buff);
 719         return err;
 720 }
 721
 722 /*
 723  * alua_stpg - Issue a SET TARGET PORT GROUP command
 724  *
 725  * Issue a SET TARGET PORT GROUP command and evaluate the
 726  * response. Returns SCSI_DH_RETRY per default to trigger
 727  * a re-evaluation of the target group state or SCSI_DH_OK
 728  * if no further action needs to be taken.
 729  */
 730 static unsigned alua_stpg(struct scsi_device *sdev, struct alua_port_group *pg)
 731 {
 732         int retval;
 733         struct scsi_sense_hdr sense_hdr;
 734
 735         if (!(pg->tpgs & TPGS_MODE_EXPLICIT)) {
 736                 /* Only implicit ALUA supported, retry */
 737                 return SCSI_DH_RETRY;
 738         }
 739         switch (pg->state) {
 740         case SCSI_ACCESS_STATE_OPTIMAL:
 741                 return SCSI_DH_OK;
 742         case SCSI_ACCESS_STATE_ACTIVE:
 743                 if ((pg->flags & ALUA_OPTIMIZE_STPG) &&
 744                     !pg->pref &&
 745                     (pg->tpgs & TPGS_MODE_IMPLICIT))
 746                         return SCSI_DH_OK;
 747                 break;
 748         case SCSI_ACCESS_STATE_STANDBY:
 749         case SCSI_ACCESS_STATE_UNAVAILABLE:
 750                 break;
 751         case SCSI_ACCESS_STATE_OFFLINE:
 752                 return SCSI_DH_IO;
 753         case SCSI_ACCESS_STATE_TRANSITIONING:
 754                 break;
 755         default:
 756                 sdev_printk(KERN_INFO, sdev,
 757                             "%s: stpg failed, unhandled TPGS state %d",
 758                             ALUA_DH_NAME, pg->state);
 759                 return SCSI_DH_NOSYS;
 760         }
 761         retval = submit_stpg(sdev, pg->group_id, &sense_hdr);
 762
 763         if (retval) {
 764                 if (!scsi_sense_valid(&sense_hdr)) {
 765                         sdev_printk(KERN_INFO, sdev,
 766                                     "%s: stpg failed, result %d",
 767                                     ALUA_DH_NAME, retval);
 768                         if (driver_byte(retval) == DRIVER_ERROR)
 769                                 return SCSI_DH_DEV_TEMP_BUSY;
 770                 } else {
 771                         sdev_printk(KERN_INFO, sdev, "%s: stpg failed\n",
 772                                     ALUA_DH_NAME);
 773                         scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 774                 }
 775         }
 776         /* Retry RTPG */
 777         return SCSI_DH_RETRY;
 778 }
 779
 780 static void alua_rtpg_work(struct work_struct *work)
 781 {
 782         struct alua_port_group *pg =
 783                 container_of(work, struct alua_port_group, rtpg_work.work);
 784         struct scsi_device *sdev;
 785         LIST_HEAD(qdata_list);
 786         int err = SCSI_DH_OK;
 787         struct alua_queue_data *qdata, *tmp;
 788         unsigned long flags;
 789
 790         spin_lock_irqsave(&pg->lock, flags);
 791         sdev = pg->rtpg_sdev;
 792         if (!sdev) {
 793                 WARN_ON(pg->flags & ALUA_PG_RUN_RTPG);
 794                 WARN_ON(pg->flags & ALUA_PG_RUN_STPG);
 795                 spin_unlock_irqrestore(&pg->lock, flags);
 796                 kref_put(&pg->kref, release_port_group);
 797                 return;
 798         }
 799         pg->flags |= ALUA_PG_RUNNING;
 800         if (pg->flags & ALUA_PG_RUN_RTPG) {
 801                 int state = pg->state;
 802
 803                 pg->flags &= ~ALUA_PG_RUN_RTPG;
 804                 spin_unlock_irqrestore(&pg->lock, flags);
 805                 if (state == SCSI_ACCESS_STATE_TRANSITIONING) {
 806                         if (alua_tur(sdev) == SCSI_DH_RETRY) {
 807                                 spin_lock_irqsave(&pg->lock, flags);
 808                                 pg->flags &= ~ALUA_PG_RUNNING;
 809                                 pg->flags |= ALUA_PG_RUN_RTPG;
 810                                 spin_unlock_irqrestore(&pg->lock, flags);
 811                                 queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 812                                                    pg->interval * HZ);
 813                                 return;
 814                         }
 815                         /* Send RTPG on failure or if TUR indicates SUCCESS */
 816                 }
 817                 err = alua_rtpg(sdev, pg);
 818                 spin_lock_irqsave(&pg->lock, flags);
 819                 if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) {
 820                         pg->flags &= ~ALUA_PG_RUNNING;
 821                         pg->flags |= ALUA_PG_RUN_RTPG;
 822                         spin_unlock_irqrestore(&pg->lock, flags);
 823                         queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 824                                            pg->interval * HZ);
 825                         return;
 826                 }
 827                 if (err != SCSI_DH_OK)
 828                         pg->flags &= ~ALUA_PG_RUN_STPG;
 829         }
 830         if (pg->flags & ALUA_PG_RUN_STPG) {
 831                 pg->flags &= ~ALUA_PG_RUN_STPG;
 832                 spin_unlock_irqrestore(&pg->lock, flags);
 833                 err = alua_stpg(sdev, pg);
 834                 spin_lock_irqsave(&pg->lock, flags);
 835                 if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) {
 836                         pg->flags |= ALUA_PG_RUN_RTPG;
 837                         pg->interval = 0;
 838                         pg->flags &= ~ALUA_PG_RUNNING;
 839                         spin_unlock_irqrestore(&pg->lock, flags);
 840                         queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 841                                            pg->interval * HZ);
 842                         return;
 843                 }
 844         }
 845
 846         list_splice_init(&pg->rtpg_list, &qdata_list);
 847         pg->rtpg_sdev = NULL;
 848         spin_unlock_irqrestore(&pg->lock, flags);
 849
 850         list_for_each_entry_safe(qdata, tmp, &qdata_list, entry) {
 851                 list_del(&qdata->entry);
 852                 if (qdata->callback_fn)
 853                         qdata->callback_fn(qdata->callback_data, err);
 854                 kfree(qdata);
 855         }
 856         spin_lock_irqsave(&pg->lock, flags);
 857         pg->flags &= ~ALUA_PG_RUNNING;
 858         spin_unlock_irqrestore(&pg->lock, flags);
 859         scsi_device_put(sdev);
 860         kref_put(&pg->kref, release_port_group);
 861 }
 862
 863 /**
 864  * alua_rtpg_queue() - cause RTPG to be submitted asynchronously
 865  * @pg: ALUA port group associated with @sdev.
 866  * @sdev: SCSI device for which to submit an RTPG.
 867  * @qdata: Information about the callback to invoke after the RTPG.
 868  * @force: Whether or not to submit an RTPG if a work item that will submit an
 869  *         RTPG already has been scheduled.
 870  *
 871  * Returns true if and only if alua_rtpg_work() will be called asynchronously.
 872  * That function is responsible for calling @qdata->fn().
 873  */
 874 static bool alua_rtpg_queue(struct alua_port_group *pg,
 875                             struct scsi_device *sdev,
 876                             struct alua_queue_data *qdata, bool force)
 877 {
 878         int start_queue = 0;
 879         unsigned long flags;
 880         if (WARN_ON_ONCE(!pg) || scsi_device_get(sdev))
 881                 return false;
 882
 883         spin_lock_irqsave(&pg->lock, flags);
 884         if (qdata) {
 885                 list_add_tail(&qdata->entry, &pg->rtpg_list);
 886                 pg->flags |= ALUA_PG_RUN_STPG;
 887                 force = true;
 888         }
 889         if (pg->rtpg_sdev == NULL) {
 890                 pg->interval = 0;
 891                 pg->flags |= ALUA_PG_RUN_RTPG;
 892                 kref_get(&pg->kref);
 893                 pg->rtpg_sdev = sdev;
 894                 start_queue = 1;
 895         } else if (!(pg->flags & ALUA_PG_RUN_RTPG) && force) {
 896                 pg->flags |= ALUA_PG_RUN_RTPG;
 897                 /* Do not queue if the worker is already running */
 898                 if (!(pg->flags & ALUA_PG_RUNNING)) {
 899                         kref_get(&pg->kref);
 900                         start_queue = 1;
 901                 }
 902         }
 903
 904         spin_unlock_irqrestore(&pg->lock, flags);
 905
 906         if (start_queue) {
 907                 if (queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 908                                 msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS)))
 909                         sdev = NULL;
 910                 else
 911                         kref_put(&pg->kref, release_port_group);
 912         }
 913         if (sdev)
 914                 scsi_device_put(sdev);
 915
 916         return true;
 917 }
 918
 919 /*
 920  * alua_initialize - Initialize ALUA state
 921  * @sdev: the device to be initialized
 922  *
 923  * For the prep_fn to work correctly we have
 924  * to initialize the ALUA state for the device.
 925  */
 926 static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h)
 927 {
 928         int err = SCSI_DH_DEV_UNSUPP, tpgs;
 929
 930         mutex_lock(&h->init_mutex);
 931         tpgs = alua_check_tpgs(sdev);
 932         if (tpgs != TPGS_MODE_NONE)
 933                 err = alua_check_vpd(sdev, h, tpgs);
 934         h->init_error = err;
 935         mutex_unlock(&h->init_mutex);
 936         return err;
 937 }
 938 /*
 939  * alua_set_params - set/unset the optimize flag
 940  * @sdev: device on the path to be activated
 941  * params - parameters in the following format
 942  *      "no_of_params\0param1\0param2\0param3\0...\0"
 943  * For example, to set the flag pass the following parameters
 944  * from multipath.conf
 945  *     hardware_handler        "2 alua 1"
 946  */
 947 static int alua_set_params(struct scsi_device *sdev, const char *params)
 948 {
 949         struct alua_dh_data *h = sdev->handler_data;
 950         struct alua_port_group *pg = NULL;
 951         unsigned int optimize = 0, argc;
 952         const char *p = params;
 953         int result = SCSI_DH_OK;
 954         unsigned long flags;
 955
 956         if ((sscanf(params, "%u", &argc) != 1) || (argc != 1))
 957                 return -EINVAL;
 958
 959         while (*p++)
 960                 ;
 961         if ((sscanf(p, "%u", &optimize) != 1) || (optimize > 1))
 962                 return -EINVAL;
 963
 964         rcu_read_lock();
 965         pg = rcu_dereference(h->pg);
 966         if (!pg) {
 967                 rcu_read_unlock();
 968                 return -ENXIO;
 969         }
 970         spin_lock_irqsave(&pg->lock, flags);
 971         if (optimize)
 972                 pg->flags |= ALUA_OPTIMIZE_STPG;
 973         else
 974                 pg->flags &= ~ALUA_OPTIMIZE_STPG;
 975         spin_unlock_irqrestore(&pg->lock, flags);
 976         rcu_read_unlock();
 977
 978         return result;
 979 }
 980
 981 /*
 982  * alua_activate - activate a path
 983  * @sdev: device on the path to be activated
 984  *
 985  * We're currently switching the port group to be activated only and
 986  * let the array figure out the rest.
 987  * There may be other arrays which require us to switch all port groups
 988  * based on a certain policy. But until we actually encounter them it
 989  * should be okay.
 990  */
 991 static int alua_activate(struct scsi_device *sdev,
 992                         activate_complete fn, void *data)
 993 {
 994         struct alua_dh_data *h = sdev->handler_data;
 995         int err = SCSI_DH_OK;
 996         struct alua_queue_data *qdata;
 997         struct alua_port_group *pg;
 998
 999         qdata = kzalloc(sizeof(*qdata), GFP_KERNEL);
1000         if (!qdata) {
1001                 err = SCSI_DH_RES_TEMP_UNAVAIL;
1002                 goto out;
1003         }
1004         qdata->callback_fn = fn;
1005         qdata->callback_data = data;
1006
1007         mutex_lock(&h->init_mutex);
1008         rcu_read_lock();
1009         pg = rcu_dereference(h->pg);
1010         if (!pg || !kref_get_unless_zero(&pg->kref)) {
1011                 rcu_read_unlock();
1012                 kfree(qdata);
1013                 err = h->init_error;
1014                 mutex_unlock(&h->init_mutex);
1015                 goto out;
1016         }
1017         rcu_read_unlock();
1018         mutex_unlock(&h->init_mutex);
1019
1020         if (alua_rtpg_queue(pg, sdev, qdata, true))
1021                 fn = NULL;
1022         else
1023                 err = SCSI_DH_DEV_OFFLINED;
1024         kref_put(&pg->kref, release_port_group);
1025 out:
1026         if (fn)
1027                 fn(data, err);
1028         return 0;
1029 }
1030
1031 /*
1032  * alua_check - check path status
1033  * @sdev: device on the path to be checked
1034  *
1035  * Check the device status
1036  */
1037 static void alua_check(struct scsi_device *sdev, bool force)
1038 {
1039         struct alua_dh_data *h = sdev->handler_data;
1040         struct alua_port_group *pg;
1041
1042         rcu_read_lock();
1043         pg = rcu_dereference(h->pg);
1044         if (!pg || !kref_get_unless_zero(&pg->kref)) {
1045                 rcu_read_unlock();
1046                 return;
1047         }
1048         rcu_read_unlock();
1049
1050         alua_rtpg_queue(pg, sdev, NULL, force);
1051         kref_put(&pg->kref, release_port_group);
1052 }
1053
1054 /*
1055  * alua_prep_fn - request callback
1056  *
1057  * Fail I/O to all paths not in state
1058  * active/optimized or active/non-optimized.
1059  */
1060 static blk_status_t alua_prep_fn(struct scsi_device *sdev, struct request *req)
1061 {
1062         struct alua_dh_data *h = sdev->handler_data;
1063         struct alua_port_group *pg;
1064         unsigned char state = SCSI_ACCESS_STATE_OPTIMAL;
1065
1066         rcu_read_lock();
1067         pg = rcu_dereference(h->pg);
1068         if (pg)
1069                 state = pg->state;
1070         rcu_read_unlock();
1071
1072         switch (state) {
1073         case SCSI_ACCESS_STATE_OPTIMAL:
1074         case SCSI_ACCESS_STATE_ACTIVE:
1075         case SCSI_ACCESS_STATE_LBA:
1076                 return BLK_STS_OK;
1077         case SCSI_ACCESS_STATE_TRANSITIONING:
1078                 return BLK_STS_RESOURCE;
1079         default:
1080                 req->rq_flags |= RQF_QUIET;
1081                 return BLK_STS_IOERR;
1082         }
1083 }
1084
1085 static void alua_rescan(struct scsi_device *sdev)
1086 {
1087         struct alua_dh_data *h = sdev->handler_data;
1088
1089         alua_initialize(sdev, h);
1090 }
1091
1092 /*
1093  * alua_bus_attach - Attach device handler
1094  * @sdev: device to be attached to
1095  */
1096 static int alua_bus_attach(struct scsi_device *sdev)
1097 {
1098         struct alua_dh_data *h;
1099         int err;
1100
1101         h = kzalloc(sizeof(*h) , GFP_KERNEL);
1102         if (!h)
1103                 return SCSI_DH_NOMEM;
1104         spin_lock_init(&h->pg_lock);
1105         rcu_assign_pointer(h->pg, NULL);
1106         h->init_error = SCSI_DH_OK;
1107         h->sdev = sdev;
1108         INIT_LIST_HEAD(&h->node);
1109
1110         mutex_init(&h->init_mutex);
1111         err = alua_initialize(sdev, h);
1112         if (err != SCSI_DH_OK && err != SCSI_DH_DEV_OFFLINED)
1113                 goto failed;
1114
1115         sdev->handler_data = h;
1116         return SCSI_DH_OK;
1117 failed:
1118         kfree(h);
1119         return err;
1120 }
1121
1122 /*
1123  * alua_bus_detach - Detach device handler
1124  * @sdev: device to be detached from
1125  */
1126 static void alua_bus_detach(struct scsi_device *sdev)
1127 {
1128         struct alua_dh_data *h = sdev->handler_data;
1129         struct alua_port_group *pg;
1130
1131         spin_lock(&h->pg_lock);
1132         pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock));
1133         rcu_assign_pointer(h->pg, NULL);
1134         h->sdev = NULL;
1135         spin_unlock(&h->pg_lock);
1136         if (pg) {
1137                 spin_lock_irq(&pg->lock);
1138                 list_del_rcu(&h->node);
1139                 spin_unlock_irq(&pg->lock);
1140                 kref_put(&pg->kref, release_port_group);
1141         }
1142         sdev->handler_data = NULL;
1143         kfree(h);
1144 }
1145
1146 static struct scsi_device_handler alua_dh = {
1147         .name = ALUA_DH_NAME,
1148         .module = THIS_MODULE,
1149         .attach = alua_bus_attach,
1150         .detach = alua_bus_detach,
1151         .prep_fn = alua_prep_fn,
1152         .check_sense = alua_check_sense,
1153         .activate = alua_activate,
1154         .rescan = alua_rescan,
1155         .set_params = alua_set_params,
1156 };
1157
1158 static int __init alua_init(void)
1159 {
1160         int r;
1161
1162         kaluad_wq = alloc_workqueue("kaluad", WQ_MEM_RECLAIM, 0);
1163         if (!kaluad_wq) {
1164                 /* Temporary failure, bypass */
1165                 return SCSI_DH_DEV_TEMP_BUSY;
1166         }
1167
1168         r = scsi_register_device_handler(&alua_dh);
1169         if (r != 0) {
1170                 printk(KERN_ERR "%s: Failed to register scsi device handler",
1171                         ALUA_DH_NAME);
1172                 destroy_workqueue(kaluad_wq);
1173         }
1174         return r;
1175 }
1176
1177 static void __exit alua_exit(void)
1178 {
1179         scsi_unregister_device_handler(&alua_dh);
1180         destroy_workqueue(kaluad_wq);
1181 }
1182
1183 module_init(alua_init);
1184 module_exit(alua_exit);
1185
1186 MODULE_DESCRIPTION("DM Multipath ALUA support");
1187 MODULE_AUTHOR("Hannes Reinecke <hare@suse.de>");
1188 MODULE_LICENSE("GPL");
1189 MODULE_VERSION(ALUA_DH_VER);