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 #define ALUA_RTPG_RETRY_DELAY           2
  44
  45 /* device handler flags */
  46 #define ALUA_OPTIMIZE_STPG              0x01
  47 #define ALUA_RTPG_EXT_HDR_UNSUPP        0x02
  48 /* State machine flags */
  49 #define ALUA_PG_RUN_RTPG                0x10
  50 #define ALUA_PG_RUN_STPG                0x20
  51 #define ALUA_PG_RUNNING                 0x40
  52
  53 static uint optimize_stpg;
  54 module_param(optimize_stpg, uint, S_IRUGO|S_IWUSR);
  55 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.");
  56
  57 static LIST_HEAD(port_group_list);
  58 static DEFINE_SPINLOCK(port_group_lock);
  59 static struct workqueue_struct *kaluad_wq;
  60
  61 struct alua_port_group {
  62         struct kref             kref;
  63         struct rcu_head         rcu;
  64         struct list_head        node;
  65         struct list_head        dh_list;
  66         unsigned char           device_id_str[256];
  67         int                     device_id_len;
  68         int                     group_id;
  69         int                     tpgs;
  70         int                     state;
  71         int                     pref;
  72         int                     valid_states;
  73         unsigned                flags; /* used for optimizing STPG */
  74         unsigned char           transition_tmo;
  75         unsigned long           expiry;
  76         unsigned long           interval;
  77         struct delayed_work     rtpg_work;
  78         spinlock_t              lock;
  79         struct list_head        rtpg_list;
  80         struct scsi_device      *rtpg_sdev;
  81 };
  82
  83 struct alua_dh_data {
  84         struct list_head        node;
  85         struct alua_port_group __rcu *pg;
  86         int                     group_id;
  87         spinlock_t              pg_lock;
  88         struct scsi_device      *sdev;
  89         int                     init_error;
  90         struct mutex            init_mutex;
  91         bool                    disabled;
  92 };
  93
  94 struct alua_queue_data {
  95         struct list_head        entry;
  96         activate_complete       callback_fn;
  97         void                    *callback_data;
  98 };
  99
 100 #define ALUA_POLICY_SWITCH_CURRENT      0
 101 #define ALUA_POLICY_SWITCH_ALL          1
 102
 103 static void alua_rtpg_work(struct work_struct *work);
 104 static bool alua_rtpg_queue(struct alua_port_group *pg,
 105                             struct scsi_device *sdev,
 106                             struct alua_queue_data *qdata, bool force);
 107 static void alua_check(struct scsi_device *sdev, bool force);
 108
 109 static void release_port_group(struct kref *kref)
 110 {
 111         struct alua_port_group *pg;
 112
 113         pg = container_of(kref, struct alua_port_group, kref);
 114         if (pg->rtpg_sdev)
 115                 flush_delayed_work(&pg->rtpg_work);
 116         spin_lock(&port_group_lock);
 117         list_del(&pg->node);
 118         spin_unlock(&port_group_lock);
 119         kfree_rcu(pg, rcu);
 120 }
 121
 122 /*
 123  * submit_rtpg - Issue a REPORT TARGET GROUP STATES command
 124  * @sdev: sdev the command should be sent to
 125  */
 126 static int submit_rtpg(struct scsi_device *sdev, unsigned char *buff,
 127                        int bufflen, struct scsi_sense_hdr *sshdr, int flags)
 128 {
 129         u8 cdb[MAX_COMMAND_SIZE];
 130         int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
 131                 REQ_FAILFAST_DRIVER;
 132
 133         /* Prepare the command. */
 134         memset(cdb, 0x0, MAX_COMMAND_SIZE);
 135         cdb[0] = MAINTENANCE_IN;
 136         if (!(flags & ALUA_RTPG_EXT_HDR_UNSUPP))
 137                 cdb[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
 138         else
 139                 cdb[1] = MI_REPORT_TARGET_PGS;
 140         put_unaligned_be32(bufflen, &cdb[6]);
 141
 142         return scsi_execute(sdev, cdb, DMA_FROM_DEVICE, buff, bufflen, NULL,
 143                         sshdr, ALUA_FAILOVER_TIMEOUT * HZ,
 144                         ALUA_FAILOVER_RETRIES, req_flags, 0, NULL);
 145 }
 146
 147 /*
 148  * submit_stpg - Issue a SET TARGET PORT GROUP command
 149  *
 150  * Currently we're only setting the current target port group state
 151  * to 'active/optimized' and let the array firmware figure out
 152  * the states of the remaining groups.
 153  */
 154 static int submit_stpg(struct scsi_device *sdev, int group_id,
 155                        struct scsi_sense_hdr *sshdr)
 156 {
 157         u8 cdb[MAX_COMMAND_SIZE];
 158         unsigned char stpg_data[8];
 159         int stpg_len = 8;
 160         int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
 161                 REQ_FAILFAST_DRIVER;
 162
 163         /* Prepare the data buffer */
 164         memset(stpg_data, 0, stpg_len);
 165         stpg_data[4] = SCSI_ACCESS_STATE_OPTIMAL;
 166         put_unaligned_be16(group_id, &stpg_data[6]);
 167
 168         /* Prepare the command. */
 169         memset(cdb, 0x0, MAX_COMMAND_SIZE);
 170         cdb[0] = MAINTENANCE_OUT;
 171         cdb[1] = MO_SET_TARGET_PGS;
 172         put_unaligned_be32(stpg_len, &cdb[6]);
 173
 174         return scsi_execute(sdev, cdb, DMA_TO_DEVICE, stpg_data, stpg_len, NULL,
 175                         sshdr, ALUA_FAILOVER_TIMEOUT * HZ,
 176                         ALUA_FAILOVER_RETRIES, req_flags, 0, NULL);
 177 }
 178
 179 static struct alua_port_group *alua_find_get_pg(char *id_str, size_t id_size,
 180                                                 int group_id)
 181 {
 182         struct alua_port_group *pg;
 183
 184         if (!id_str || !id_size || !strlen(id_str))
 185                 return NULL;
 186
 187         list_for_each_entry(pg, &port_group_list, node) {
 188                 if (pg->group_id != group_id)
 189                         continue;
 190                 if (!pg->device_id_len || pg->device_id_len != id_size)
 191                         continue;
 192                 if (strncmp(pg->device_id_str, id_str, id_size))
 193                         continue;
 194                 if (!kref_get_unless_zero(&pg->kref))
 195                         continue;
 196                 return pg;
 197         }
 198
 199         return NULL;
 200 }
 201
 202 /*
 203  * alua_alloc_pg - Allocate a new port_group structure
 204  * @sdev: scsi device
 205  * @group_id: port group id
 206  * @tpgs: target port group settings
 207  *
 208  * Allocate a new port_group structure for a given
 209  * device.
 210  */
 211 static struct alua_port_group *alua_alloc_pg(struct scsi_device *sdev,
 212                                              int group_id, int tpgs)
 213 {
 214         struct alua_port_group *pg, *tmp_pg;
 215
 216         pg = kzalloc(sizeof(struct alua_port_group), GFP_KERNEL);
 217         if (!pg)
 218                 return ERR_PTR(-ENOMEM);
 219
 220         pg->device_id_len = scsi_vpd_lun_id(sdev, pg->device_id_str,
 221                                             sizeof(pg->device_id_str));
 222         if (pg->device_id_len <= 0) {
 223                 /*
 224                  * TPGS supported but no device identification found.
 225                  * Generate private device identification.
 226                  */
 227                 sdev_printk(KERN_INFO, sdev,
 228                             "%s: No device descriptors found\n",
 229                             ALUA_DH_NAME);
 230                 pg->device_id_str[0] = '\0';
 231                 pg->device_id_len = 0;
 232         }
 233         pg->group_id = group_id;
 234         pg->tpgs = tpgs;
 235         pg->state = SCSI_ACCESS_STATE_OPTIMAL;
 236         pg->valid_states = TPGS_SUPPORT_ALL;
 237         if (optimize_stpg)
 238                 pg->flags |= ALUA_OPTIMIZE_STPG;
 239         kref_init(&pg->kref);
 240         INIT_DELAYED_WORK(&pg->rtpg_work, alua_rtpg_work);
 241         INIT_LIST_HEAD(&pg->rtpg_list);
 242         INIT_LIST_HEAD(&pg->node);
 243         INIT_LIST_HEAD(&pg->dh_list);
 244         spin_lock_init(&pg->lock);
 245
 246         spin_lock(&port_group_lock);
 247         tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len,
 248                                   group_id);
 249         if (tmp_pg) {
 250                 spin_unlock(&port_group_lock);
 251                 kfree(pg);
 252                 return tmp_pg;
 253         }
 254
 255         list_add(&pg->node, &port_group_list);
 256         spin_unlock(&port_group_lock);
 257
 258         return pg;
 259 }
 260
 261 /*
 262  * alua_check_tpgs - Evaluate TPGS setting
 263  * @sdev: device to be checked
 264  *
 265  * Examine the TPGS setting of the sdev to find out if ALUA
 266  * is supported.
 267  */
 268 static int alua_check_tpgs(struct scsi_device *sdev)
 269 {
 270         int tpgs = TPGS_MODE_NONE;
 271
 272         /*
 273          * ALUA support for non-disk devices is fraught with
 274          * difficulties, so disable it for now.
 275          */
 276         if (sdev->type != TYPE_DISK) {
 277                 sdev_printk(KERN_INFO, sdev,
 278                             "%s: disable for non-disk devices\n",
 279                             ALUA_DH_NAME);
 280                 return tpgs;
 281         }
 282
 283         tpgs = scsi_device_tpgs(sdev);
 284         switch (tpgs) {
 285         case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT:
 286                 sdev_printk(KERN_INFO, sdev,
 287                             "%s: supports implicit and explicit TPGS\n",
 288                             ALUA_DH_NAME);
 289                 break;
 290         case TPGS_MODE_EXPLICIT:
 291                 sdev_printk(KERN_INFO, sdev, "%s: supports explicit TPGS\n",
 292                             ALUA_DH_NAME);
 293                 break;
 294         case TPGS_MODE_IMPLICIT:
 295                 sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n",
 296                             ALUA_DH_NAME);
 297                 break;
 298         case TPGS_MODE_NONE:
 299                 sdev_printk(KERN_INFO, sdev, "%s: not supported\n",
 300                             ALUA_DH_NAME);
 301                 break;
 302         default:
 303                 sdev_printk(KERN_INFO, sdev,
 304                             "%s: unsupported TPGS setting %d\n",
 305                             ALUA_DH_NAME, tpgs);
 306                 tpgs = TPGS_MODE_NONE;
 307                 break;
 308         }
 309
 310         return tpgs;
 311 }
 312
 313 /*
 314  * alua_check_vpd - Evaluate INQUIRY vpd page 0x83
 315  * @sdev: device to be checked
 316  *
 317  * Extract the relative target port and the target port group
 318  * descriptor from the list of identificators.
 319  */
 320 static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h,
 321                           int tpgs)
 322 {
 323         int rel_port = -1, group_id;
 324         struct alua_port_group *pg, *old_pg = NULL;
 325         bool pg_updated = false;
 326         unsigned long flags;
 327
 328         group_id = scsi_vpd_tpg_id(sdev, &rel_port);
 329         if (group_id < 0) {
 330                 /*
 331                  * Internal error; TPGS supported but required
 332                  * VPD identification descriptors not present.
 333                  * Disable ALUA support
 334                  */
 335                 sdev_printk(KERN_INFO, sdev,
 336                             "%s: No target port descriptors found\n",
 337                             ALUA_DH_NAME);
 338                 return SCSI_DH_DEV_UNSUPP;
 339         }
 340
 341         pg = alua_alloc_pg(sdev, group_id, tpgs);
 342         if (IS_ERR(pg)) {
 343                 if (PTR_ERR(pg) == -ENOMEM)
 344                         return SCSI_DH_NOMEM;
 345                 return SCSI_DH_DEV_UNSUPP;
 346         }
 347         if (pg->device_id_len)
 348                 sdev_printk(KERN_INFO, sdev,
 349                             "%s: device %s port group %x rel port %x\n",
 350                             ALUA_DH_NAME, pg->device_id_str,
 351                             group_id, rel_port);
 352         else
 353                 sdev_printk(KERN_INFO, sdev,
 354                             "%s: port group %x rel port %x\n",
 355                             ALUA_DH_NAME, group_id, rel_port);
 356
 357         /* Check for existing port group references */
 358         spin_lock(&h->pg_lock);
 359         old_pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock));
 360         if (old_pg != pg) {
 361                 /* port group has changed. Update to new port group */
 362                 if (h->pg) {
 363                         spin_lock_irqsave(&old_pg->lock, flags);
 364                         list_del_rcu(&h->node);
 365                         spin_unlock_irqrestore(&old_pg->lock, flags);
 366                 }
 367                 rcu_assign_pointer(h->pg, pg);
 368                 pg_updated = true;
 369         }
 370
 371         spin_lock_irqsave(&pg->lock, flags);
 372         if (pg_updated)
 373                 list_add_rcu(&h->node, &pg->dh_list);
 374         spin_unlock_irqrestore(&pg->lock, flags);
 375
 376         alua_rtpg_queue(rcu_dereference_protected(h->pg,
 377                                                   lockdep_is_held(&h->pg_lock)),
 378                         sdev, NULL, true);
 379         spin_unlock(&h->pg_lock);
 380
 381         if (old_pg)
 382                 kref_put(&old_pg->kref, release_port_group);
 383
 384         return SCSI_DH_OK;
 385 }
 386
 387 static char print_alua_state(unsigned char state)
 388 {
 389         switch (state) {
 390         case SCSI_ACCESS_STATE_OPTIMAL:
 391                 return 'A';
 392         case SCSI_ACCESS_STATE_ACTIVE:
 393                 return 'N';
 394         case SCSI_ACCESS_STATE_STANDBY:
 395                 return 'S';
 396         case SCSI_ACCESS_STATE_UNAVAILABLE:
 397                 return 'U';
 398         case SCSI_ACCESS_STATE_LBA:
 399                 return 'L';
 400         case SCSI_ACCESS_STATE_OFFLINE:
 401                 return 'O';
 402         case SCSI_ACCESS_STATE_TRANSITIONING:
 403                 return 'T';
 404         default:
 405                 return 'X';
 406         }
 407 }
 408
 409 static enum scsi_disposition alua_check_sense(struct scsi_device *sdev,
 410                                               struct scsi_sense_hdr *sense_hdr)
 411 {
 412         struct alua_dh_data *h = sdev->handler_data;
 413         struct alua_port_group *pg;
 414
 415         switch (sense_hdr->sense_key) {
 416         case NOT_READY:
 417                 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) {
 418                         /*
 419                          * LUN Not Accessible - ALUA state transition
 420                          */
 421                         rcu_read_lock();
 422                         pg = rcu_dereference(h->pg);
 423                         if (pg)
 424                                 pg->state = SCSI_ACCESS_STATE_TRANSITIONING;
 425                         rcu_read_unlock();
 426                         alua_check(sdev, false);
 427                         return NEEDS_RETRY;
 428                 }
 429                 break;
 430         case UNIT_ATTENTION:
 431                 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) {
 432                         /*
 433                          * Power On, Reset, or Bus Device Reset.
 434                          * Might have obscured a state transition,
 435                          * so schedule a recheck.
 436                          */
 437                         alua_check(sdev, true);
 438                         return ADD_TO_MLQUEUE;
 439                 }
 440                 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04)
 441                         /*
 442                          * Device internal reset
 443                          */
 444                         return ADD_TO_MLQUEUE;
 445                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01)
 446                         /*
 447                          * Mode Parameters Changed
 448                          */
 449                         return ADD_TO_MLQUEUE;
 450                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06) {
 451                         /*
 452                          * ALUA state changed
 453                          */
 454                         alua_check(sdev, true);
 455                         return ADD_TO_MLQUEUE;
 456                 }
 457                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07) {
 458                         /*
 459                          * Implicit ALUA state transition failed
 460                          */
 461                         alua_check(sdev, true);
 462                         return ADD_TO_MLQUEUE;
 463                 }
 464                 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03)
 465                         /*
 466                          * Inquiry data has changed
 467                          */
 468                         return ADD_TO_MLQUEUE;
 469                 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x0e)
 470                         /*
 471                          * REPORTED_LUNS_DATA_HAS_CHANGED is reported
 472                          * when switching controllers on targets like
 473                          * Intel Multi-Flex. We can just retry.
 474                          */
 475                         return ADD_TO_MLQUEUE;
 476                 break;
 477         }
 478
 479         return SCSI_RETURN_NOT_HANDLED;
 480 }
 481
 482 /*
 483  * alua_tur - Send a TEST UNIT READY
 484  * @sdev: device to which the TEST UNIT READY command should be send
 485  *
 486  * Send a TEST UNIT READY to @sdev to figure out the device state
 487  * Returns SCSI_DH_RETRY if the sense code is NOT READY/ALUA TRANSITIONING,
 488  * SCSI_DH_OK if no error occurred, and SCSI_DH_IO otherwise.
 489  */
 490 static int alua_tur(struct scsi_device *sdev)
 491 {
 492         struct scsi_sense_hdr sense_hdr;
 493         int retval;
 494
 495         retval = scsi_test_unit_ready(sdev, ALUA_FAILOVER_TIMEOUT * HZ,
 496                                       ALUA_FAILOVER_RETRIES, &sense_hdr);
 497         if (sense_hdr.sense_key == NOT_READY &&
 498             sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a)
 499                 return SCSI_DH_RETRY;
 500         else if (retval)
 501                 return SCSI_DH_IO;
 502         else
 503                 return SCSI_DH_OK;
 504 }
 505
 506 /*
 507  * alua_rtpg - Evaluate REPORT TARGET GROUP STATES
 508  * @sdev: the device to be evaluated.
 509  *
 510  * Evaluate the Target Port Group State.
 511  * Returns SCSI_DH_DEV_OFFLINED if the path is
 512  * found to be unusable.
 513  */
 514 static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
 515 {
 516         struct scsi_sense_hdr sense_hdr;
 517         struct alua_port_group *tmp_pg;
 518         int len, k, off, bufflen = ALUA_RTPG_SIZE;
 519         int group_id_old, state_old, pref_old, valid_states_old;
 520         unsigned char *desc, *buff;
 521         unsigned err;
 522         int retval;
 523         unsigned int tpg_desc_tbl_off;
 524         unsigned char orig_transition_tmo;
 525         unsigned long flags;
 526         bool transitioning_sense = false;
 527
 528         group_id_old = pg->group_id;
 529         state_old = pg->state;
 530         pref_old = pg->pref;
 531         valid_states_old = pg->valid_states;
 532
 533         if (!pg->expiry) {
 534                 unsigned long transition_tmo = ALUA_FAILOVER_TIMEOUT * HZ;
 535
 536                 if (pg->transition_tmo)
 537                         transition_tmo = pg->transition_tmo * HZ;
 538
 539                 pg->expiry = round_jiffies_up(jiffies + transition_tmo);
 540         }
 541
 542         buff = kzalloc(bufflen, GFP_KERNEL);
 543         if (!buff)
 544                 return SCSI_DH_DEV_TEMP_BUSY;
 545
 546  retry:
 547         err = 0;
 548         retval = submit_rtpg(sdev, buff, bufflen, &sense_hdr, pg->flags);
 549
 550         if (retval) {
 551                 /*
 552                  * Some (broken) implementations have a habit of returning
 553                  * an error during things like firmware update etc.
 554                  * But if the target only supports active/optimized there's
 555                  * not much we can do; it's not that we can switch paths
 556                  * or anything.
 557                  * So ignore any errors to avoid spurious failures during
 558                  * path failover.
 559                  */
 560                 if ((pg->valid_states & ~TPGS_SUPPORT_OPTIMIZED) == 0) {
 561                         sdev_printk(KERN_INFO, sdev,
 562                                     "%s: ignoring rtpg result %d\n",
 563                                     ALUA_DH_NAME, retval);
 564                         kfree(buff);
 565                         return SCSI_DH_OK;
 566                 }
 567                 if (retval < 0 || !scsi_sense_valid(&sense_hdr)) {
 568                         sdev_printk(KERN_INFO, sdev,
 569                                     "%s: rtpg failed, result %d\n",
 570                                     ALUA_DH_NAME, retval);
 571                         kfree(buff);
 572                         if (retval < 0)
 573                                 return SCSI_DH_DEV_TEMP_BUSY;
 574                         if (host_byte(retval) == DID_NO_CONNECT)
 575                                 return SCSI_DH_RES_TEMP_UNAVAIL;
 576                         return SCSI_DH_IO;
 577                 }
 578
 579                 /*
 580                  * submit_rtpg() has failed on existing arrays
 581                  * when requesting extended header info, and
 582                  * the array doesn't support extended headers,
 583                  * even though it shouldn't according to T10.
 584                  * The retry without rtpg_ext_hdr_req set
 585                  * handles this.
 586                  * Note:  some arrays return a sense key of ILLEGAL_REQUEST
 587                  * with ASC 00h if they don't support the extended header.
 588                  */
 589                 if (!(pg->flags & ALUA_RTPG_EXT_HDR_UNSUPP) &&
 590                     sense_hdr.sense_key == ILLEGAL_REQUEST) {
 591                         pg->flags |= ALUA_RTPG_EXT_HDR_UNSUPP;
 592                         goto retry;
 593                 }
 594                 /*
 595                  * If the array returns with 'ALUA state transition'
 596                  * sense code here it cannot return RTPG data during
 597                  * transition. So set the state to 'transitioning' directly.
 598                  */
 599                 if (sense_hdr.sense_key == NOT_READY &&
 600                     sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) {
 601                         transitioning_sense = true;
 602                         goto skip_rtpg;
 603                 }
 604                 /*
 605                  * Retry on any other UNIT ATTENTION occurred.
 606                  */
 607                 if (sense_hdr.sense_key == UNIT_ATTENTION)
 608                         err = SCSI_DH_RETRY;
 609                 if (err == SCSI_DH_RETRY &&
 610                     pg->expiry != 0 && time_before(jiffies, pg->expiry)) {
 611                         sdev_printk(KERN_ERR, sdev, "%s: rtpg retry\n",
 612                                     ALUA_DH_NAME);
 613                         scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 614                         kfree(buff);
 615                         return err;
 616                 }
 617                 sdev_printk(KERN_ERR, sdev, "%s: rtpg failed\n",
 618                             ALUA_DH_NAME);
 619                 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 620                 kfree(buff);
 621                 pg->expiry = 0;
 622                 return SCSI_DH_IO;
 623         }
 624
 625         len = get_unaligned_be32(&buff[0]) + 4;
 626
 627         if (len > bufflen) {
 628                 /* Resubmit with the correct length */
 629                 kfree(buff);
 630                 bufflen = len;
 631                 buff = kmalloc(bufflen, GFP_KERNEL);
 632                 if (!buff) {
 633                         sdev_printk(KERN_WARNING, sdev,
 634                                     "%s: kmalloc buffer failed\n",__func__);
 635                         /* Temporary failure, bypass */
 636                         pg->expiry = 0;
 637                         return SCSI_DH_DEV_TEMP_BUSY;
 638                 }
 639                 goto retry;
 640         }
 641
 642         orig_transition_tmo = pg->transition_tmo;
 643         if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR && buff[5] != 0)
 644                 pg->transition_tmo = buff[5];
 645         else
 646                 pg->transition_tmo = ALUA_FAILOVER_TIMEOUT;
 647
 648         if (orig_transition_tmo != pg->transition_tmo) {
 649                 sdev_printk(KERN_INFO, sdev,
 650                             "%s: transition timeout set to %d seconds\n",
 651                             ALUA_DH_NAME, pg->transition_tmo);
 652                 pg->expiry = jiffies + pg->transition_tmo * HZ;
 653         }
 654
 655         if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR)
 656                 tpg_desc_tbl_off = 8;
 657         else
 658                 tpg_desc_tbl_off = 4;
 659
 660         for (k = tpg_desc_tbl_off, desc = buff + tpg_desc_tbl_off;
 661              k < len;
 662              k += off, desc += off) {
 663                 u16 group_id = get_unaligned_be16(&desc[2]);
 664
 665                 spin_lock_irqsave(&port_group_lock, flags);
 666                 tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len,
 667                                           group_id);
 668                 spin_unlock_irqrestore(&port_group_lock, flags);
 669                 if (tmp_pg) {
 670                         if (spin_trylock_irqsave(&tmp_pg->lock, flags)) {
 671                                 if ((tmp_pg == pg) ||
 672                                     !(tmp_pg->flags & ALUA_PG_RUNNING)) {
 673                                         struct alua_dh_data *h;
 674
 675                                         tmp_pg->state = desc[0] & 0x0f;
 676                                         tmp_pg->pref = desc[0] >> 7;
 677                                         rcu_read_lock();
 678                                         list_for_each_entry_rcu(h,
 679                                                 &tmp_pg->dh_list, node) {
 680                                                 if (!h->sdev)
 681                                                         continue;
 682                                                 h->sdev->access_state = desc[0];
 683                                         }
 684                                         rcu_read_unlock();
 685                                 }
 686                                 if (tmp_pg == pg)
 687                                         tmp_pg->valid_states = desc[1];
 688                                 spin_unlock_irqrestore(&tmp_pg->lock, flags);
 689                         }
 690                         kref_put(&tmp_pg->kref, release_port_group);
 691                 }
 692                 off = 8 + (desc[7] * 4);
 693         }
 694
 695  skip_rtpg:
 696         spin_lock_irqsave(&pg->lock, flags);
 697         if (transitioning_sense)
 698                 pg->state = SCSI_ACCESS_STATE_TRANSITIONING;
 699
 700         if (group_id_old != pg->group_id || state_old != pg->state ||
 701                 pref_old != pg->pref || valid_states_old != pg->valid_states)
 702                 sdev_printk(KERN_INFO, sdev,
 703                         "%s: port group %02x state %c %s supports %c%c%c%c%c%c%c\n",
 704                         ALUA_DH_NAME, pg->group_id, print_alua_state(pg->state),
 705                         pg->pref ? "preferred" : "non-preferred",
 706                         pg->valid_states&TPGS_SUPPORT_TRANSITION?'T':'t',
 707                         pg->valid_states&TPGS_SUPPORT_OFFLINE?'O':'o',
 708                         pg->valid_states&TPGS_SUPPORT_LBA_DEPENDENT?'L':'l',
 709                         pg->valid_states&TPGS_SUPPORT_UNAVAILABLE?'U':'u',
 710                         pg->valid_states&TPGS_SUPPORT_STANDBY?'S':'s',
 711                         pg->valid_states&TPGS_SUPPORT_NONOPTIMIZED?'N':'n',
 712                         pg->valid_states&TPGS_SUPPORT_OPTIMIZED?'A':'a');
 713
 714         switch (pg->state) {
 715         case SCSI_ACCESS_STATE_TRANSITIONING:
 716                 if (time_before(jiffies, pg->expiry)) {
 717                         /* State transition, retry */
 718                         pg->interval = ALUA_RTPG_RETRY_DELAY;
 719                         err = SCSI_DH_RETRY;
 720                 } else {
 721                         struct alua_dh_data *h;
 722
 723                         /* Transitioning time exceeded, set port to standby */
 724                         err = SCSI_DH_IO;
 725                         pg->state = SCSI_ACCESS_STATE_STANDBY;
 726                         pg->expiry = 0;
 727                         rcu_read_lock();
 728                         list_for_each_entry_rcu(h, &pg->dh_list, node) {
 729                                 if (!h->sdev)
 730                                         continue;
 731                                 h->sdev->access_state =
 732                                         (pg->state & SCSI_ACCESS_STATE_MASK);
 733                                 if (pg->pref)
 734                                         h->sdev->access_state |=
 735                                                 SCSI_ACCESS_STATE_PREFERRED;
 736                         }
 737                         rcu_read_unlock();
 738                 }
 739                 break;
 740         case SCSI_ACCESS_STATE_OFFLINE:
 741                 /* Path unusable */
 742                 err = SCSI_DH_DEV_OFFLINED;
 743                 pg->expiry = 0;
 744                 break;
 745         default:
 746                 /* Useable path if active */
 747                 err = SCSI_DH_OK;
 748                 pg->expiry = 0;
 749                 break;
 750         }
 751         spin_unlock_irqrestore(&pg->lock, flags);
 752         kfree(buff);
 753         return err;
 754 }
 755
 756 /*
 757  * alua_stpg - Issue a SET TARGET PORT GROUP command
 758  *
 759  * Issue a SET TARGET PORT GROUP command and evaluate the
 760  * response. Returns SCSI_DH_RETRY per default to trigger
 761  * a re-evaluation of the target group state or SCSI_DH_OK
 762  * if no further action needs to be taken.
 763  */
 764 static unsigned alua_stpg(struct scsi_device *sdev, struct alua_port_group *pg)
 765 {
 766         int retval;
 767         struct scsi_sense_hdr sense_hdr;
 768
 769         if (!(pg->tpgs & TPGS_MODE_EXPLICIT)) {
 770                 /* Only implicit ALUA supported, retry */
 771                 return SCSI_DH_RETRY;
 772         }
 773         switch (pg->state) {
 774         case SCSI_ACCESS_STATE_OPTIMAL:
 775                 return SCSI_DH_OK;
 776         case SCSI_ACCESS_STATE_ACTIVE:
 777                 if ((pg->flags & ALUA_OPTIMIZE_STPG) &&
 778                     !pg->pref &&
 779                     (pg->tpgs & TPGS_MODE_IMPLICIT))
 780                         return SCSI_DH_OK;
 781                 break;
 782         case SCSI_ACCESS_STATE_STANDBY:
 783         case SCSI_ACCESS_STATE_UNAVAILABLE:
 784                 break;
 785         case SCSI_ACCESS_STATE_OFFLINE:
 786                 return SCSI_DH_IO;
 787         case SCSI_ACCESS_STATE_TRANSITIONING:
 788                 break;
 789         default:
 790                 sdev_printk(KERN_INFO, sdev,
 791                             "%s: stpg failed, unhandled TPGS state %d",
 792                             ALUA_DH_NAME, pg->state);
 793                 return SCSI_DH_NOSYS;
 794         }
 795         retval = submit_stpg(sdev, pg->group_id, &sense_hdr);
 796
 797         if (retval) {
 798                 if (retval < 0 || !scsi_sense_valid(&sense_hdr)) {
 799                         sdev_printk(KERN_INFO, sdev,
 800                                     "%s: stpg failed, result %d",
 801                                     ALUA_DH_NAME, retval);
 802                         if (retval < 0)
 803                                 return SCSI_DH_DEV_TEMP_BUSY;
 804                 } else {
 805                         sdev_printk(KERN_INFO, sdev, "%s: stpg failed\n",
 806                                     ALUA_DH_NAME);
 807                         scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 808                 }
 809         }
 810         /* Retry RTPG */
 811         return SCSI_DH_RETRY;
 812 }
 813
 814 static bool alua_rtpg_select_sdev(struct alua_port_group *pg)
 815 {
 816         struct alua_dh_data *h;
 817         struct scsi_device *sdev = NULL;
 818
 819         lockdep_assert_held(&pg->lock);
 820         if (WARN_ON(!pg->rtpg_sdev))
 821                 return false;
 822
 823         /*
 824          * RCU protection isn't necessary for dh_list here
 825          * as we hold pg->lock, but for access to h->pg.
 826          */
 827         rcu_read_lock();
 828         list_for_each_entry_rcu(h, &pg->dh_list, node) {
 829                 if (!h->sdev)
 830                         continue;
 831                 if (h->sdev == pg->rtpg_sdev) {
 832                         h->disabled = true;
 833                         continue;
 834                 }
 835                 if (rcu_dereference(h->pg) == pg &&
 836                     !h->disabled &&
 837                     !scsi_device_get(h->sdev)) {
 838                         sdev = h->sdev;
 839                         break;
 840                 }
 841         }
 842         rcu_read_unlock();
 843
 844         if (!sdev) {
 845                 pr_warn("%s: no device found for rtpg\n",
 846                         (pg->device_id_len ?
 847                          (char *)pg->device_id_str : "(nameless PG)"));
 848                 return false;
 849         }
 850
 851         sdev_printk(KERN_INFO, sdev, "rtpg retry on different device\n");
 852
 853         scsi_device_put(pg->rtpg_sdev);
 854         pg->rtpg_sdev = sdev;
 855
 856         return true;
 857 }
 858
 859 static void alua_rtpg_work(struct work_struct *work)
 860 {
 861         struct alua_port_group *pg =
 862                 container_of(work, struct alua_port_group, rtpg_work.work);
 863         struct scsi_device *sdev;
 864         LIST_HEAD(qdata_list);
 865         int err = SCSI_DH_OK;
 866         struct alua_queue_data *qdata, *tmp;
 867         struct alua_dh_data *h;
 868         unsigned long flags;
 869
 870         spin_lock_irqsave(&pg->lock, flags);
 871         sdev = pg->rtpg_sdev;
 872         if (!sdev) {
 873                 WARN_ON(pg->flags & ALUA_PG_RUN_RTPG);
 874                 WARN_ON(pg->flags & ALUA_PG_RUN_STPG);
 875                 spin_unlock_irqrestore(&pg->lock, flags);
 876                 kref_put(&pg->kref, release_port_group);
 877                 return;
 878         }
 879         pg->flags |= ALUA_PG_RUNNING;
 880         if (pg->flags & ALUA_PG_RUN_RTPG) {
 881                 int state = pg->state;
 882
 883                 pg->flags &= ~ALUA_PG_RUN_RTPG;
 884                 spin_unlock_irqrestore(&pg->lock, flags);
 885                 if (state == SCSI_ACCESS_STATE_TRANSITIONING) {
 886                         if (alua_tur(sdev) == SCSI_DH_RETRY) {
 887                                 spin_lock_irqsave(&pg->lock, flags);
 888                                 pg->flags &= ~ALUA_PG_RUNNING;
 889                                 pg->flags |= ALUA_PG_RUN_RTPG;
 890                                 if (!pg->interval)
 891                                         pg->interval = ALUA_RTPG_RETRY_DELAY;
 892                                 spin_unlock_irqrestore(&pg->lock, flags);
 893                                 queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 894                                                    pg->interval * HZ);
 895                                 return;
 896                         }
 897                         /* Send RTPG on failure or if TUR indicates SUCCESS */
 898                 }
 899                 err = alua_rtpg(sdev, pg);
 900                 spin_lock_irqsave(&pg->lock, flags);
 901
 902                 /* If RTPG failed on the current device, try using another */
 903                 if (err == SCSI_DH_RES_TEMP_UNAVAIL &&
 904                     alua_rtpg_select_sdev(pg))
 905                         err = SCSI_DH_IMM_RETRY;
 906
 907                 if (err == SCSI_DH_RETRY || err == SCSI_DH_IMM_RETRY ||
 908                     pg->flags & ALUA_PG_RUN_RTPG) {
 909                         pg->flags &= ~ALUA_PG_RUNNING;
 910                         if (err == SCSI_DH_IMM_RETRY)
 911                                 pg->interval = 0;
 912                         else if (!pg->interval && !(pg->flags & ALUA_PG_RUN_RTPG))
 913                                 pg->interval = ALUA_RTPG_RETRY_DELAY;
 914                         pg->flags |= ALUA_PG_RUN_RTPG;
 915                         spin_unlock_irqrestore(&pg->lock, flags);
 916                         queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 917                                            pg->interval * HZ);
 918                         return;
 919                 }
 920                 if (err != SCSI_DH_OK)
 921                         pg->flags &= ~ALUA_PG_RUN_STPG;
 922         }
 923         if (pg->flags & ALUA_PG_RUN_STPG) {
 924                 pg->flags &= ~ALUA_PG_RUN_STPG;
 925                 spin_unlock_irqrestore(&pg->lock, flags);
 926                 err = alua_stpg(sdev, pg);
 927                 spin_lock_irqsave(&pg->lock, flags);
 928                 if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) {
 929                         pg->flags |= ALUA_PG_RUN_RTPG;
 930                         pg->interval = 0;
 931                         pg->flags &= ~ALUA_PG_RUNNING;
 932                         spin_unlock_irqrestore(&pg->lock, flags);
 933                         queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 934                                            pg->interval * HZ);
 935                         return;
 936                 }
 937         }
 938
 939         list_splice_init(&pg->rtpg_list, &qdata_list);
 940         /*
 941          * We went through an RTPG, for good or bad.
 942          * Re-enable all devices for the next attempt.
 943          */
 944         list_for_each_entry(h, &pg->dh_list, node)
 945                 h->disabled = false;
 946         pg->rtpg_sdev = NULL;
 947         spin_unlock_irqrestore(&pg->lock, flags);
 948
 949         list_for_each_entry_safe(qdata, tmp, &qdata_list, entry) {
 950                 list_del(&qdata->entry);
 951                 if (qdata->callback_fn)
 952                         qdata->callback_fn(qdata->callback_data, err);
 953                 kfree(qdata);
 954         }
 955         spin_lock_irqsave(&pg->lock, flags);
 956         pg->flags &= ~ALUA_PG_RUNNING;
 957         spin_unlock_irqrestore(&pg->lock, flags);
 958         scsi_device_put(sdev);
 959         kref_put(&pg->kref, release_port_group);
 960 }
 961
 962 /**
 963  * alua_rtpg_queue() - cause RTPG to be submitted asynchronously
 964  * @pg: ALUA port group associated with @sdev.
 965  * @sdev: SCSI device for which to submit an RTPG.
 966  * @qdata: Information about the callback to invoke after the RTPG.
 967  * @force: Whether or not to submit an RTPG if a work item that will submit an
 968  *         RTPG already has been scheduled.
 969  *
 970  * Returns true if and only if alua_rtpg_work() will be called asynchronously.
 971  * That function is responsible for calling @qdata->fn().
 972  */
 973 static bool alua_rtpg_queue(struct alua_port_group *pg,
 974                             struct scsi_device *sdev,
 975                             struct alua_queue_data *qdata, bool force)
 976 {
 977         int start_queue = 0;
 978         unsigned long flags;
 979         if (WARN_ON_ONCE(!pg) || scsi_device_get(sdev))
 980                 return false;
 981
 982         spin_lock_irqsave(&pg->lock, flags);
 983         if (qdata) {
 984                 list_add_tail(&qdata->entry, &pg->rtpg_list);
 985                 pg->flags |= ALUA_PG_RUN_STPG;
 986                 force = true;
 987         }
 988         if (pg->rtpg_sdev == NULL) {
 989                 pg->interval = 0;
 990                 pg->flags |= ALUA_PG_RUN_RTPG;
 991                 kref_get(&pg->kref);
 992                 pg->rtpg_sdev = sdev;
 993                 start_queue = 1;
 994         } else if (!(pg->flags & ALUA_PG_RUN_RTPG) && force) {
 995                 pg->flags |= ALUA_PG_RUN_RTPG;
 996                 /* Do not queue if the worker is already running */
 997                 if (!(pg->flags & ALUA_PG_RUNNING)) {
 998                         kref_get(&pg->kref);
 999                         start_queue = 1;
1000                 }
1001         }
1002
1003         spin_unlock_irqrestore(&pg->lock, flags);
1004
1005         if (start_queue) {
1006                 if (queue_delayed_work(kaluad_wq, &pg->rtpg_work,
1007                                 msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS)))
1008                         sdev = NULL;
1009                 else
1010                         kref_put(&pg->kref, release_port_group);
1011         }
1012         if (sdev)
1013                 scsi_device_put(sdev);
1014
1015         return true;
1016 }
1017
1018 /*
1019  * alua_initialize - Initialize ALUA state
1020  * @sdev: the device to be initialized
1021  *
1022  * For the prep_fn to work correctly we have
1023  * to initialize the ALUA state for the device.
1024  */
1025 static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h)
1026 {
1027         int err = SCSI_DH_DEV_UNSUPP, tpgs;
1028
1029         mutex_lock(&h->init_mutex);
1030         h->disabled = false;
1031         tpgs = alua_check_tpgs(sdev);
1032         if (tpgs != TPGS_MODE_NONE)
1033                 err = alua_check_vpd(sdev, h, tpgs);
1034         h->init_error = err;
1035         mutex_unlock(&h->init_mutex);
1036         return err;
1037 }
1038 /*
1039  * alua_set_params - set/unset the optimize flag
1040  * @sdev: device on the path to be activated
1041  * params - parameters in the following format
1042  *      "no_of_params\0param1\0param2\0param3\0...\0"
1043  * For example, to set the flag pass the following parameters
1044  * from multipath.conf
1045  *     hardware_handler        "2 alua 1"
1046  */
1047 static int alua_set_params(struct scsi_device *sdev, const char *params)
1048 {
1049         struct alua_dh_data *h = sdev->handler_data;
1050         struct alua_port_group *pg = NULL;
1051         unsigned int optimize = 0, argc;
1052         const char *p = params;
1053         int result = SCSI_DH_OK;
1054         unsigned long flags;
1055
1056         if ((sscanf(params, "%u", &argc) != 1) || (argc != 1))
1057                 return -EINVAL;
1058
1059         while (*p++)
1060                 ;
1061         if ((sscanf(p, "%u", &optimize) != 1) || (optimize > 1))
1062                 return -EINVAL;
1063
1064         rcu_read_lock();
1065         pg = rcu_dereference(h->pg);
1066         if (!pg) {
1067                 rcu_read_unlock();
1068                 return -ENXIO;
1069         }
1070         spin_lock_irqsave(&pg->lock, flags);
1071         if (optimize)
1072                 pg->flags |= ALUA_OPTIMIZE_STPG;
1073         else
1074                 pg->flags &= ~ALUA_OPTIMIZE_STPG;
1075         spin_unlock_irqrestore(&pg->lock, flags);
1076         rcu_read_unlock();
1077
1078         return result;
1079 }
1080
1081 /*
1082  * alua_activate - activate a path
1083  * @sdev: device on the path to be activated
1084  *
1085  * We're currently switching the port group to be activated only and
1086  * let the array figure out the rest.
1087  * There may be other arrays which require us to switch all port groups
1088  * based on a certain policy. But until we actually encounter them it
1089  * should be okay.
1090  */
1091 static int alua_activate(struct scsi_device *sdev,
1092                         activate_complete fn, void *data)
1093 {
1094         struct alua_dh_data *h = sdev->handler_data;
1095         int err = SCSI_DH_OK;
1096         struct alua_queue_data *qdata;
1097         struct alua_port_group *pg;
1098
1099         qdata = kzalloc(sizeof(*qdata), GFP_KERNEL);
1100         if (!qdata) {
1101                 err = SCSI_DH_RES_TEMP_UNAVAIL;
1102                 goto out;
1103         }
1104         qdata->callback_fn = fn;
1105         qdata->callback_data = data;
1106
1107         mutex_lock(&h->init_mutex);
1108         rcu_read_lock();
1109         pg = rcu_dereference(h->pg);
1110         if (!pg || !kref_get_unless_zero(&pg->kref)) {
1111                 rcu_read_unlock();
1112                 kfree(qdata);
1113                 err = h->init_error;
1114                 mutex_unlock(&h->init_mutex);
1115                 goto out;
1116         }
1117         rcu_read_unlock();
1118         mutex_unlock(&h->init_mutex);
1119
1120         if (alua_rtpg_queue(pg, sdev, qdata, true))
1121                 fn = NULL;
1122         else
1123                 err = SCSI_DH_DEV_OFFLINED;
1124         kref_put(&pg->kref, release_port_group);
1125 out:
1126         if (fn)
1127                 fn(data, err);
1128         return 0;
1129 }
1130
1131 /*
1132  * alua_check - check path status
1133  * @sdev: device on the path to be checked
1134  *
1135  * Check the device status
1136  */
1137 static void alua_check(struct scsi_device *sdev, bool force)
1138 {
1139         struct alua_dh_data *h = sdev->handler_data;
1140         struct alua_port_group *pg;
1141
1142         rcu_read_lock();
1143         pg = rcu_dereference(h->pg);
1144         if (!pg || !kref_get_unless_zero(&pg->kref)) {
1145                 rcu_read_unlock();
1146                 return;
1147         }
1148         rcu_read_unlock();
1149         alua_rtpg_queue(pg, sdev, NULL, force);
1150         kref_put(&pg->kref, release_port_group);
1151 }
1152
1153 /*
1154  * alua_prep_fn - request callback
1155  *
1156  * Fail I/O to all paths not in state
1157  * active/optimized or active/non-optimized.
1158  */
1159 static blk_status_t alua_prep_fn(struct scsi_device *sdev, struct request *req)
1160 {
1161         struct alua_dh_data *h = sdev->handler_data;
1162         struct alua_port_group *pg;
1163         unsigned char state = SCSI_ACCESS_STATE_OPTIMAL;
1164
1165         rcu_read_lock();
1166         pg = rcu_dereference(h->pg);
1167         if (pg)
1168                 state = pg->state;
1169         rcu_read_unlock();
1170
1171         switch (state) {
1172         case SCSI_ACCESS_STATE_OPTIMAL:
1173         case SCSI_ACCESS_STATE_ACTIVE:
1174         case SCSI_ACCESS_STATE_LBA:
1175                 return BLK_STS_OK;
1176         case SCSI_ACCESS_STATE_TRANSITIONING:
1177                 return BLK_STS_AGAIN;
1178         default:
1179                 req->rq_flags |= RQF_QUIET;
1180                 return BLK_STS_IOERR;
1181         }
1182 }
1183
1184 static void alua_rescan(struct scsi_device *sdev)
1185 {
1186         struct alua_dh_data *h = sdev->handler_data;
1187
1188         alua_initialize(sdev, h);
1189 }
1190
1191 /*
1192  * alua_bus_attach - Attach device handler
1193  * @sdev: device to be attached to
1194  */
1195 static int alua_bus_attach(struct scsi_device *sdev)
1196 {
1197         struct alua_dh_data *h;
1198         int err;
1199
1200         h = kzalloc(sizeof(*h) , GFP_KERNEL);
1201         if (!h)
1202                 return SCSI_DH_NOMEM;
1203         spin_lock_init(&h->pg_lock);
1204         rcu_assign_pointer(h->pg, NULL);
1205         h->init_error = SCSI_DH_OK;
1206         h->sdev = sdev;
1207         INIT_LIST_HEAD(&h->node);
1208
1209         mutex_init(&h->init_mutex);
1210         err = alua_initialize(sdev, h);
1211         if (err != SCSI_DH_OK && err != SCSI_DH_DEV_OFFLINED)
1212                 goto failed;
1213
1214         sdev->handler_data = h;
1215         return SCSI_DH_OK;
1216 failed:
1217         kfree(h);
1218         return err;
1219 }
1220
1221 /*
1222  * alua_bus_detach - Detach device handler
1223  * @sdev: device to be detached from
1224  */
1225 static void alua_bus_detach(struct scsi_device *sdev)
1226 {
1227         struct alua_dh_data *h = sdev->handler_data;
1228         struct alua_port_group *pg;
1229
1230         spin_lock(&h->pg_lock);
1231         pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock));
1232         rcu_assign_pointer(h->pg, NULL);
1233         spin_unlock(&h->pg_lock);
1234         if (pg) {
1235                 spin_lock_irq(&pg->lock);
1236                 list_del_rcu(&h->node);
1237                 spin_unlock_irq(&pg->lock);
1238                 kref_put(&pg->kref, release_port_group);
1239         }
1240         sdev->handler_data = NULL;
1241         synchronize_rcu();
1242         kfree(h);
1243 }
1244
1245 static struct scsi_device_handler alua_dh = {
1246         .name = ALUA_DH_NAME,
1247         .module = THIS_MODULE,
1248         .attach = alua_bus_attach,
1249         .detach = alua_bus_detach,
1250         .prep_fn = alua_prep_fn,
1251         .check_sense = alua_check_sense,
1252         .activate = alua_activate,
1253         .rescan = alua_rescan,
1254         .set_params = alua_set_params,
1255 };
1256
1257 static int __init alua_init(void)
1258 {
1259         int r;
1260
1261         kaluad_wq = alloc_workqueue("kaluad", WQ_MEM_RECLAIM, 0);
1262         if (!kaluad_wq)
1263                 return -ENOMEM;
1264
1265         r = scsi_register_device_handler(&alua_dh);
1266         if (r != 0) {
1267                 printk(KERN_ERR "%s: Failed to register scsi device handler",
1268                         ALUA_DH_NAME);
1269                 destroy_workqueue(kaluad_wq);
1270         }
1271         return r;
1272 }
1273
1274 static void __exit alua_exit(void)
1275 {
1276         scsi_unregister_device_handler(&alua_dh);
1277         destroy_workqueue(kaluad_wq);
1278 }
1279
1280 module_init(alua_init);
1281 module_exit(alua_exit);
1282
1283 MODULE_DESCRIPTION("DM Multipath ALUA support");
1284 MODULE_AUTHOR("Hannes Reinecke <hare@suse.de>");
1285 MODULE_LICENSE("GPL");
1286 MODULE_VERSION(ALUA_DH_VER);