drivers/scsi/device_handler/scsi_dh_alua.c

   1 /*
   2  * Generic SCSI-3 ALUA SCSI Device Handler
   3  *
   4  * Copyright (C) 2007-2010 Hannes Reinecke, SUSE Linux Products GmbH.
   5  * All rights reserved.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  20  *
  21  */
  22 #include <linux/slab.h>
  23 #include <linux/delay.h>
  24 #include <linux/module.h>
  25 #include <asm/unaligned.h>
  26 #include <scsi/scsi.h>
  27 #include <scsi/scsi_proto.h>
  28 #include <scsi/scsi_dbg.h>
  29 #include <scsi/scsi_eh.h>
  30 #include <scsi/scsi_dh.h>
  31
  32 #define ALUA_DH_NAME "alua"
  33 #define ALUA_DH_VER "2.0"
  34
  35 #define TPGS_SUPPORT_NONE               0x00
  36 #define TPGS_SUPPORT_OPTIMIZED          0x01
  37 #define TPGS_SUPPORT_NONOPTIMIZED       0x02
  38 #define TPGS_SUPPORT_STANDBY            0x04
  39 #define TPGS_SUPPORT_UNAVAILABLE        0x08
  40 #define TPGS_SUPPORT_LBA_DEPENDENT      0x10
  41 #define TPGS_SUPPORT_OFFLINE            0x40
  42 #define TPGS_SUPPORT_TRANSITION         0x80
  43
  44 #define RTPG_FMT_MASK                   0x70
  45 #define RTPG_FMT_EXT_HDR                0x10
  46
  47 #define TPGS_MODE_UNINITIALIZED          -1
  48 #define TPGS_MODE_NONE                  0x0
  49 #define TPGS_MODE_IMPLICIT              0x1
  50 #define TPGS_MODE_EXPLICIT              0x2
  51
  52 #define ALUA_RTPG_SIZE                  128
  53 #define ALUA_FAILOVER_TIMEOUT           60
  54 #define ALUA_FAILOVER_RETRIES           5
  55 #define ALUA_RTPG_DELAY_MSECS           5
  56
  57 /* device handler flags */
  58 #define ALUA_OPTIMIZE_STPG              0x01
  59 #define ALUA_RTPG_EXT_HDR_UNSUPP        0x02
  60 /* State machine flags */
  61 #define ALUA_PG_RUN_RTPG                0x10
  62 #define ALUA_PG_RUN_STPG                0x20
  63 #define ALUA_PG_RUNNING                 0x40
  64
  65 static uint optimize_stpg;
  66 module_param(optimize_stpg, uint, S_IRUGO|S_IWUSR);
  67 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.");
  68
  69 static LIST_HEAD(port_group_list);
  70 static DEFINE_SPINLOCK(port_group_lock);
  71 static struct workqueue_struct *kaluad_wq;
  72
  73 struct alua_port_group {
  74         struct kref             kref;
  75         struct rcu_head         rcu;
  76         struct list_head        node;
  77         struct list_head        dh_list;
  78         unsigned char           device_id_str[256];
  79         int                     device_id_len;
  80         int                     group_id;
  81         int                     tpgs;
  82         int                     state;
  83         int                     pref;
  84         unsigned                flags; /* used for optimizing STPG */
  85         unsigned char           transition_tmo;
  86         unsigned long           expiry;
  87         unsigned long           interval;
  88         struct delayed_work     rtpg_work;
  89         spinlock_t              lock;
  90         struct list_head        rtpg_list;
  91         struct scsi_device      *rtpg_sdev;
  92 };
  93
  94 struct alua_dh_data {
  95         struct list_head        node;
  96         struct alua_port_group __rcu *pg;
  97         int                     group_id;
  98         spinlock_t              pg_lock;
  99         struct scsi_device      *sdev;
 100         int                     init_error;
 101         struct mutex            init_mutex;
 102 };
 103
 104 struct alua_queue_data {
 105         struct list_head        entry;
 106         activate_complete       callback_fn;
 107         void                    *callback_data;
 108 };
 109
 110 #define ALUA_POLICY_SWITCH_CURRENT      0
 111 #define ALUA_POLICY_SWITCH_ALL          1
 112
 113 static void alua_rtpg_work(struct work_struct *work);
 114 static bool alua_rtpg_queue(struct alua_port_group *pg,
 115                             struct scsi_device *sdev,
 116                             struct alua_queue_data *qdata, bool force);
 117 static void alua_check(struct scsi_device *sdev, bool force);
 118
 119 static void release_port_group(struct kref *kref)
 120 {
 121         struct alua_port_group *pg;
 122
 123         pg = container_of(kref, struct alua_port_group, kref);
 124         if (pg->rtpg_sdev)
 125                 flush_delayed_work(&pg->rtpg_work);
 126         spin_lock(&port_group_lock);
 127         list_del(&pg->node);
 128         spin_unlock(&port_group_lock);
 129         kfree_rcu(pg, rcu);
 130 }
 131
 132 /*
 133  * submit_rtpg - Issue a REPORT TARGET GROUP STATES command
 134  * @sdev: sdev the command should be sent to
 135  */
 136 static int submit_rtpg(struct scsi_device *sdev, unsigned char *buff,
 137                        int bufflen, struct scsi_sense_hdr *sshdr, int flags)
 138 {
 139         u8 cdb[COMMAND_SIZE(MAINTENANCE_IN)];
 140         int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
 141                 REQ_FAILFAST_DRIVER;
 142
 143         /* Prepare the command. */
 144         memset(cdb, 0x0, COMMAND_SIZE(MAINTENANCE_IN));
 145         cdb[0] = MAINTENANCE_IN;
 146         if (!(flags & ALUA_RTPG_EXT_HDR_UNSUPP))
 147                 cdb[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
 148         else
 149                 cdb[1] = MI_REPORT_TARGET_PGS;
 150         put_unaligned_be32(bufflen, &cdb[6]);
 151
 152         return scsi_execute(sdev, cdb, DMA_FROM_DEVICE, buff, bufflen, NULL,
 153                         sshdr, ALUA_FAILOVER_TIMEOUT * HZ,
 154                         ALUA_FAILOVER_RETRIES, req_flags, 0, NULL);
 155 }
 156
 157 /*
 158  * submit_stpg - Issue a SET TARGET PORT GROUP command
 159  *
 160  * Currently we're only setting the current target port group state
 161  * to 'active/optimized' and let the array firmware figure out
 162  * the states of the remaining groups.
 163  */
 164 static int submit_stpg(struct scsi_device *sdev, int group_id,
 165                        struct scsi_sense_hdr *sshdr)
 166 {
 167         u8 cdb[COMMAND_SIZE(MAINTENANCE_OUT)];
 168         unsigned char stpg_data[8];
 169         int stpg_len = 8;
 170         int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
 171                 REQ_FAILFAST_DRIVER;
 172
 173         /* Prepare the data buffer */
 174         memset(stpg_data, 0, stpg_len);
 175         stpg_data[4] = SCSI_ACCESS_STATE_OPTIMAL;
 176         put_unaligned_be16(group_id, &stpg_data[6]);
 177
 178         /* Prepare the command. */
 179         memset(cdb, 0x0, COMMAND_SIZE(MAINTENANCE_OUT));
 180         cdb[0] = MAINTENANCE_OUT;
 181         cdb[1] = MO_SET_TARGET_PGS;
 182         put_unaligned_be32(stpg_len, &cdb[6]);
 183
 184         return scsi_execute(sdev, cdb, DMA_TO_DEVICE, stpg_data, stpg_len, NULL,
 185                         sshdr, ALUA_FAILOVER_TIMEOUT * HZ,
 186                         ALUA_FAILOVER_RETRIES, req_flags, 0, NULL);
 187 }
 188
 189 static struct alua_port_group *alua_find_get_pg(char *id_str, size_t id_size,
 190                                                 int group_id)
 191 {
 192         struct alua_port_group *pg;
 193
 194         if (!id_str || !id_size || !strlen(id_str))
 195                 return NULL;
 196
 197         list_for_each_entry(pg, &port_group_list, node) {
 198                 if (pg->group_id != group_id)
 199                         continue;
 200                 if (!pg->device_id_len || pg->device_id_len != id_size)
 201                         continue;
 202                 if (strncmp(pg->device_id_str, id_str, id_size))
 203                         continue;
 204                 if (!kref_get_unless_zero(&pg->kref))
 205                         continue;
 206                 return pg;
 207         }
 208
 209         return NULL;
 210 }
 211
 212 /*
 213  * alua_alloc_pg - Allocate a new port_group structure
 214  * @sdev: scsi device
 215  * @h: alua device_handler data
 216  * @group_id: port group id
 217  *
 218  * Allocate a new port_group structure for a given
 219  * device.
 220  */
 221 static struct alua_port_group *alua_alloc_pg(struct scsi_device *sdev,
 222                                              int group_id, int tpgs)
 223 {
 224         struct alua_port_group *pg, *tmp_pg;
 225
 226         pg = kzalloc(sizeof(struct alua_port_group), GFP_KERNEL);
 227         if (!pg)
 228                 return ERR_PTR(-ENOMEM);
 229
 230         pg->device_id_len = scsi_vpd_lun_id(sdev, pg->device_id_str,
 231                                             sizeof(pg->device_id_str));
 232         if (pg->device_id_len <= 0) {
 233                 /*
 234                  * TPGS supported but no device identification found.
 235                  * Generate private device identification.
 236                  */
 237                 sdev_printk(KERN_INFO, sdev,
 238                             "%s: No device descriptors found\n",
 239                             ALUA_DH_NAME);
 240                 pg->device_id_str[0] = '\0';
 241                 pg->device_id_len = 0;
 242         }
 243         pg->group_id = group_id;
 244         pg->tpgs = tpgs;
 245         pg->state = SCSI_ACCESS_STATE_OPTIMAL;
 246         if (optimize_stpg)
 247                 pg->flags |= ALUA_OPTIMIZE_STPG;
 248         kref_init(&pg->kref);
 249         INIT_DELAYED_WORK(&pg->rtpg_work, alua_rtpg_work);
 250         INIT_LIST_HEAD(&pg->rtpg_list);
 251         INIT_LIST_HEAD(&pg->node);
 252         INIT_LIST_HEAD(&pg->dh_list);
 253         spin_lock_init(&pg->lock);
 254
 255         spin_lock(&port_group_lock);
 256         tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len,
 257                                   group_id);
 258         if (tmp_pg) {
 259                 spin_unlock(&port_group_lock);
 260                 kfree(pg);
 261                 return tmp_pg;
 262         }
 263
 264         list_add(&pg->node, &port_group_list);
 265         spin_unlock(&port_group_lock);
 266
 267         return pg;
 268 }
 269
 270 /*
 271  * alua_check_tpgs - Evaluate TPGS setting
 272  * @sdev: device to be checked
 273  *
 274  * Examine the TPGS setting of the sdev to find out if ALUA
 275  * is supported.
 276  */
 277 static int alua_check_tpgs(struct scsi_device *sdev)
 278 {
 279         int tpgs = TPGS_MODE_NONE;
 280
 281         /*
 282          * ALUA support for non-disk devices is fraught with
 283          * difficulties, so disable it for now.
 284          */
 285         if (sdev->type != TYPE_DISK) {
 286                 sdev_printk(KERN_INFO, sdev,
 287                             "%s: disable for non-disk devices\n",
 288                             ALUA_DH_NAME);
 289                 return tpgs;
 290         }
 291
 292         tpgs = scsi_device_tpgs(sdev);
 293         switch (tpgs) {
 294         case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT:
 295                 sdev_printk(KERN_INFO, sdev,
 296                             "%s: supports implicit and explicit TPGS\n",
 297                             ALUA_DH_NAME);
 298                 break;
 299         case TPGS_MODE_EXPLICIT:
 300                 sdev_printk(KERN_INFO, sdev, "%s: supports explicit TPGS\n",
 301                             ALUA_DH_NAME);
 302                 break;
 303         case TPGS_MODE_IMPLICIT:
 304                 sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n",
 305                             ALUA_DH_NAME);
 306                 break;
 307         case TPGS_MODE_NONE:
 308                 sdev_printk(KERN_INFO, sdev, "%s: not supported\n",
 309                             ALUA_DH_NAME);
 310                 break;
 311         default:
 312                 sdev_printk(KERN_INFO, sdev,
 313                             "%s: unsupported TPGS setting %d\n",
 314                             ALUA_DH_NAME, tpgs);
 315                 tpgs = TPGS_MODE_NONE;
 316                 break;
 317         }
 318
 319         return tpgs;
 320 }
 321
 322 /*
 323  * alua_check_vpd - Evaluate INQUIRY vpd page 0x83
 324  * @sdev: device to be checked
 325  *
 326  * Extract the relative target port and the target port group
 327  * descriptor from the list of identificators.
 328  */
 329 static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h,
 330                           int tpgs)
 331 {
 332         int rel_port = -1, group_id;
 333         struct alua_port_group *pg, *old_pg = NULL;
 334         bool pg_updated = false;
 335         unsigned long flags;
 336
 337         group_id = scsi_vpd_tpg_id(sdev, &rel_port);
 338         if (group_id < 0) {
 339                 /*
 340                  * Internal error; TPGS supported but required
 341                  * VPD identification descriptors not present.
 342                  * Disable ALUA support
 343                  */
 344                 sdev_printk(KERN_INFO, sdev,
 345                             "%s: No target port descriptors found\n",
 346                             ALUA_DH_NAME);
 347                 return SCSI_DH_DEV_UNSUPP;
 348         }
 349
 350         pg = alua_alloc_pg(sdev, group_id, tpgs);
 351         if (IS_ERR(pg)) {
 352                 if (PTR_ERR(pg) == -ENOMEM)
 353                         return SCSI_DH_NOMEM;
 354                 return SCSI_DH_DEV_UNSUPP;
 355         }
 356         if (pg->device_id_len)
 357                 sdev_printk(KERN_INFO, sdev,
 358                             "%s: device %s port group %x rel port %x\n",
 359                             ALUA_DH_NAME, pg->device_id_str,
 360                             group_id, rel_port);
 361         else
 362                 sdev_printk(KERN_INFO, sdev,
 363                             "%s: port group %x rel port %x\n",
 364                             ALUA_DH_NAME, group_id, rel_port);
 365
 366         /* Check for existing port group references */
 367         spin_lock(&h->pg_lock);
 368         old_pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock));
 369         if (old_pg != pg) {
 370                 /* port group has changed. Update to new port group */
 371                 if (h->pg) {
 372                         spin_lock_irqsave(&old_pg->lock, flags);
 373                         list_del_rcu(&h->node);
 374                         spin_unlock_irqrestore(&old_pg->lock, flags);
 375                 }
 376                 rcu_assign_pointer(h->pg, pg);
 377                 pg_updated = true;
 378         }
 379
 380         spin_lock_irqsave(&pg->lock, flags);
 381         if (pg_updated)
 382                 list_add_rcu(&h->node, &pg->dh_list);
 383         spin_unlock_irqrestore(&pg->lock, flags);
 384
 385         alua_rtpg_queue(rcu_dereference_protected(h->pg,
 386                                                   lockdep_is_held(&h->pg_lock)),
 387                         sdev, NULL, true);
 388         spin_unlock(&h->pg_lock);
 389
 390         if (old_pg)
 391                 kref_put(&old_pg->kref, release_port_group);
 392
 393         return SCSI_DH_OK;
 394 }
 395
 396 static char print_alua_state(unsigned char state)
 397 {
 398         switch (state) {
 399         case SCSI_ACCESS_STATE_OPTIMAL:
 400                 return 'A';
 401         case SCSI_ACCESS_STATE_ACTIVE:
 402                 return 'N';
 403         case SCSI_ACCESS_STATE_STANDBY:
 404                 return 'S';
 405         case SCSI_ACCESS_STATE_UNAVAILABLE:
 406                 return 'U';
 407         case SCSI_ACCESS_STATE_LBA:
 408                 return 'L';
 409         case SCSI_ACCESS_STATE_OFFLINE:
 410                 return 'O';
 411         case SCSI_ACCESS_STATE_TRANSITIONING:
 412                 return 'T';
 413         default:
 414                 return 'X';
 415         }
 416 }
 417
 418 static int alua_check_sense(struct scsi_device *sdev,
 419                             struct scsi_sense_hdr *sense_hdr)
 420 {
 421         switch (sense_hdr->sense_key) {
 422         case NOT_READY:
 423                 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) {
 424                         /*
 425                          * LUN Not Accessible - ALUA state transition
 426                          */
 427                         alua_check(sdev, false);
 428                         return NEEDS_RETRY;
 429                 }
 430                 break;
 431         case UNIT_ATTENTION:
 432                 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) {
 433                         /*
 434                          * Power On, Reset, or Bus Device Reset.
 435                          * Might have obscured a state transition,
 436                          * so schedule a recheck.
 437                          */
 438                         alua_check(sdev, true);
 439                         return ADD_TO_MLQUEUE;
 440                 }
 441                 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04)
 442                         /*
 443                          * Device internal reset
 444                          */
 445                         return ADD_TO_MLQUEUE;
 446                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01)
 447                         /*
 448                          * Mode Parameters Changed
 449                          */
 450                         return ADD_TO_MLQUEUE;
 451                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06) {
 452                         /*
 453                          * ALUA state changed
 454                          */
 455                         alua_check(sdev, true);
 456                         return ADD_TO_MLQUEUE;
 457                 }
 458                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07) {
 459                         /*
 460                          * Implicit ALUA state transition failed
 461                          */
 462                         alua_check(sdev, true);
 463                         return ADD_TO_MLQUEUE;
 464                 }
 465                 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03)
 466                         /*
 467                          * Inquiry data has changed
 468                          */
 469                         return ADD_TO_MLQUEUE;
 470                 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x0e)
 471                         /*
 472                          * REPORTED_LUNS_DATA_HAS_CHANGED is reported
 473                          * when switching controllers on targets like
 474                          * Intel Multi-Flex. We can just retry.
 475                          */
 476                         return ADD_TO_MLQUEUE;
 477                 break;
 478         }
 479
 480         return SCSI_RETURN_NOT_HANDLED;
 481 }
 482
 483 /*
 484  * alua_tur - Send a TEST UNIT READY
 485  * @sdev: device to which the TEST UNIT READY command should be send
 486  *
 487  * Send a TEST UNIT READY to @sdev to figure out the device state
 488  * Returns SCSI_DH_RETRY if the sense code is NOT READY/ALUA TRANSITIONING,
 489  * SCSI_DH_OK if no error occurred, and SCSI_DH_IO otherwise.
 490  */
 491 static int alua_tur(struct scsi_device *sdev)
 492 {
 493         struct scsi_sense_hdr sense_hdr;
 494         int retval;
 495
 496         retval = scsi_test_unit_ready(sdev, ALUA_FAILOVER_TIMEOUT * HZ,
 497                                       ALUA_FAILOVER_RETRIES, &sense_hdr);
 498         if (sense_hdr.sense_key == NOT_READY &&
 499             sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a)
 500                 return SCSI_DH_RETRY;
 501         else if (retval)
 502                 return SCSI_DH_IO;
 503         else
 504                 return SCSI_DH_OK;
 505 }
 506
 507 /*
 508  * alua_rtpg - Evaluate REPORT TARGET GROUP STATES
 509  * @sdev: the device to be evaluated.
 510  *
 511  * Evaluate the Target Port Group State.
 512  * Returns SCSI_DH_DEV_OFFLINED if the path is
 513  * found to be unusable.
 514  */
 515 static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
 516 {
 517         struct scsi_sense_hdr sense_hdr;
 518         struct alua_port_group *tmp_pg;
 519         int len, k, off, valid_states = 0, bufflen = ALUA_RTPG_SIZE;
 520         unsigned char *desc, *buff;
 521         unsigned err, retval;
 522         unsigned int tpg_desc_tbl_off;
 523         unsigned char orig_transition_tmo;
 524         unsigned long flags;
 525
 526         if (!pg->expiry) {
 527                 unsigned long transition_tmo = ALUA_FAILOVER_TIMEOUT * HZ;
 528
 529                 if (pg->transition_tmo)
 530                         transition_tmo = pg->transition_tmo * HZ;
 531
 532                 pg->expiry = round_jiffies_up(jiffies + transition_tmo);
 533         }
 534
 535         buff = kzalloc(bufflen, GFP_KERNEL);
 536         if (!buff)
 537                 return SCSI_DH_DEV_TEMP_BUSY;
 538
 539  retry:
 540         err = 0;
 541         retval = submit_rtpg(sdev, buff, bufflen, &sense_hdr, pg->flags);
 542
 543         if (retval) {
 544                 if (!scsi_sense_valid(&sense_hdr)) {
 545                         sdev_printk(KERN_INFO, sdev,
 546                                     "%s: rtpg failed, result %d\n",
 547                                     ALUA_DH_NAME, retval);
 548                         kfree(buff);
 549                         if (driver_byte(retval) == DRIVER_ERROR)
 550                                 return SCSI_DH_DEV_TEMP_BUSY;
 551                         return SCSI_DH_IO;
 552                 }
 553
 554                 /*
 555                  * submit_rtpg() has failed on existing arrays
 556                  * when requesting extended header info, and
 557                  * the array doesn't support extended headers,
 558                  * even though it shouldn't according to T10.
 559                  * The retry without rtpg_ext_hdr_req set
 560                  * handles this.
 561                  */
 562                 if (!(pg->flags & ALUA_RTPG_EXT_HDR_UNSUPP) &&
 563                     sense_hdr.sense_key == ILLEGAL_REQUEST &&
 564                     sense_hdr.asc == 0x24 && sense_hdr.ascq == 0) {
 565                         pg->flags |= ALUA_RTPG_EXT_HDR_UNSUPP;
 566                         goto retry;
 567                 }
 568                 /*
 569                  * Retry on ALUA state transition or if any
 570                  * UNIT ATTENTION occurred.
 571                  */
 572                 if (sense_hdr.sense_key == NOT_READY &&
 573                     sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a)
 574                         err = SCSI_DH_RETRY;
 575                 else if (sense_hdr.sense_key == UNIT_ATTENTION)
 576                         err = SCSI_DH_RETRY;
 577                 if (err == SCSI_DH_RETRY &&
 578                     pg->expiry != 0 && time_before(jiffies, pg->expiry)) {
 579                         sdev_printk(KERN_ERR, sdev, "%s: rtpg retry\n",
 580                                     ALUA_DH_NAME);
 581                         scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 582                         kfree(buff);
 583                         return err;
 584                 }
 585                 sdev_printk(KERN_ERR, sdev, "%s: rtpg failed\n",
 586                             ALUA_DH_NAME);
 587                 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 588                 kfree(buff);
 589                 pg->expiry = 0;
 590                 return SCSI_DH_IO;
 591         }
 592
 593         len = get_unaligned_be32(&buff[0]) + 4;
 594
 595         if (len > bufflen) {
 596                 /* Resubmit with the correct length */
 597                 kfree(buff);
 598                 bufflen = len;
 599                 buff = kmalloc(bufflen, GFP_KERNEL);
 600                 if (!buff) {
 601                         sdev_printk(KERN_WARNING, sdev,
 602                                     "%s: kmalloc buffer failed\n",__func__);
 603                         /* Temporary failure, bypass */
 604                         pg->expiry = 0;
 605                         return SCSI_DH_DEV_TEMP_BUSY;
 606                 }
 607                 goto retry;
 608         }
 609
 610         orig_transition_tmo = pg->transition_tmo;
 611         if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR && buff[5] != 0)
 612                 pg->transition_tmo = buff[5];
 613         else
 614                 pg->transition_tmo = ALUA_FAILOVER_TIMEOUT;
 615
 616         if (orig_transition_tmo != pg->transition_tmo) {
 617                 sdev_printk(KERN_INFO, sdev,
 618                             "%s: transition timeout set to %d seconds\n",
 619                             ALUA_DH_NAME, pg->transition_tmo);
 620                 pg->expiry = jiffies + pg->transition_tmo * HZ;
 621         }
 622
 623         if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR)
 624                 tpg_desc_tbl_off = 8;
 625         else
 626                 tpg_desc_tbl_off = 4;
 627
 628         for (k = tpg_desc_tbl_off, desc = buff + tpg_desc_tbl_off;
 629              k < len;
 630              k += off, desc += off) {
 631                 u16 group_id = get_unaligned_be16(&desc[2]);
 632
 633                 spin_lock_irqsave(&port_group_lock, flags);
 634                 tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len,
 635                                           group_id);
 636                 spin_unlock_irqrestore(&port_group_lock, flags);
 637                 if (tmp_pg) {
 638                         if (spin_trylock_irqsave(&tmp_pg->lock, flags)) {
 639                                 if ((tmp_pg == pg) ||
 640                                     !(tmp_pg->flags & ALUA_PG_RUNNING)) {
 641                                         struct alua_dh_data *h;
 642
 643                                         tmp_pg->state = desc[0] & 0x0f;
 644                                         tmp_pg->pref = desc[0] >> 7;
 645                                         rcu_read_lock();
 646                                         list_for_each_entry_rcu(h,
 647                                                 &tmp_pg->dh_list, node) {
 648                                                 /* h->sdev should always be valid */
 649                                                 BUG_ON(!h->sdev);
 650                                                 h->sdev->access_state = desc[0];
 651                                         }
 652                                         rcu_read_unlock();
 653                                 }
 654                                 if (tmp_pg == pg)
 655                                         valid_states = desc[1];
 656                                 spin_unlock_irqrestore(&tmp_pg->lock, flags);
 657                         }
 658                         kref_put(&tmp_pg->kref, release_port_group);
 659                 }
 660                 off = 8 + (desc[7] * 4);
 661         }
 662
 663         spin_lock_irqsave(&pg->lock, flags);
 664         sdev_printk(KERN_INFO, sdev,
 665                     "%s: port group %02x state %c %s supports %c%c%c%c%c%c%c\n",
 666                     ALUA_DH_NAME, pg->group_id, print_alua_state(pg->state),
 667                     pg->pref ? "preferred" : "non-preferred",
 668                     valid_states&TPGS_SUPPORT_TRANSITION?'T':'t',
 669                     valid_states&TPGS_SUPPORT_OFFLINE?'O':'o',
 670                     valid_states&TPGS_SUPPORT_LBA_DEPENDENT?'L':'l',
 671                     valid_states&TPGS_SUPPORT_UNAVAILABLE?'U':'u',
 672                     valid_states&TPGS_SUPPORT_STANDBY?'S':'s',
 673                     valid_states&TPGS_SUPPORT_NONOPTIMIZED?'N':'n',
 674                     valid_states&TPGS_SUPPORT_OPTIMIZED?'A':'a');
 675
 676         switch (pg->state) {
 677         case SCSI_ACCESS_STATE_TRANSITIONING:
 678                 if (time_before(jiffies, pg->expiry)) {
 679                         /* State transition, retry */
 680                         pg->interval = 2;
 681                         err = SCSI_DH_RETRY;
 682                 } else {
 683                         struct alua_dh_data *h;
 684
 685                         /* Transitioning time exceeded, set port to standby */
 686                         err = SCSI_DH_IO;
 687                         pg->state = SCSI_ACCESS_STATE_STANDBY;
 688                         pg->expiry = 0;
 689                         rcu_read_lock();
 690                         list_for_each_entry_rcu(h, &pg->dh_list, node) {
 691                                 BUG_ON(!h->sdev);
 692                                 h->sdev->access_state =
 693                                         (pg->state & SCSI_ACCESS_STATE_MASK);
 694                                 if (pg->pref)
 695                                         h->sdev->access_state |=
 696                                                 SCSI_ACCESS_STATE_PREFERRED;
 697                         }
 698                         rcu_read_unlock();
 699                 }
 700                 break;
 701         case SCSI_ACCESS_STATE_OFFLINE:
 702                 /* Path unusable */
 703                 err = SCSI_DH_DEV_OFFLINED;
 704                 pg->expiry = 0;
 705                 break;
 706         default:
 707                 /* Useable path if active */
 708                 err = SCSI_DH_OK;
 709                 pg->expiry = 0;
 710                 break;
 711         }
 712         spin_unlock_irqrestore(&pg->lock, flags);
 713         kfree(buff);
 714         return err;
 715 }
 716
 717 /*
 718  * alua_stpg - Issue a SET TARGET PORT GROUP command
 719  *
 720  * Issue a SET TARGET PORT GROUP command and evaluate the
 721  * response. Returns SCSI_DH_RETRY per default to trigger
 722  * a re-evaluation of the target group state or SCSI_DH_OK
 723  * if no further action needs to be taken.
 724  */
 725 static unsigned alua_stpg(struct scsi_device *sdev, struct alua_port_group *pg)
 726 {
 727         int retval;
 728         struct scsi_sense_hdr sense_hdr;
 729
 730         if (!(pg->tpgs & TPGS_MODE_EXPLICIT)) {
 731                 /* Only implicit ALUA supported, retry */
 732                 return SCSI_DH_RETRY;
 733         }
 734         switch (pg->state) {
 735         case SCSI_ACCESS_STATE_OPTIMAL:
 736                 return SCSI_DH_OK;
 737         case SCSI_ACCESS_STATE_ACTIVE:
 738                 if ((pg->flags & ALUA_OPTIMIZE_STPG) &&
 739                     !pg->pref &&
 740                     (pg->tpgs & TPGS_MODE_IMPLICIT))
 741                         return SCSI_DH_OK;
 742                 break;
 743         case SCSI_ACCESS_STATE_STANDBY:
 744         case SCSI_ACCESS_STATE_UNAVAILABLE:
 745                 break;
 746         case SCSI_ACCESS_STATE_OFFLINE:
 747                 return SCSI_DH_IO;
 748         case SCSI_ACCESS_STATE_TRANSITIONING:
 749                 break;
 750         default:
 751                 sdev_printk(KERN_INFO, sdev,
 752                             "%s: stpg failed, unhandled TPGS state %d",
 753                             ALUA_DH_NAME, pg->state);
 754                 return SCSI_DH_NOSYS;
 755         }
 756         retval = submit_stpg(sdev, pg->group_id, &sense_hdr);
 757
 758         if (retval) {
 759                 if (!scsi_sense_valid(&sense_hdr)) {
 760                         sdev_printk(KERN_INFO, sdev,
 761                                     "%s: stpg failed, result %d",
 762                                     ALUA_DH_NAME, retval);
 763                         if (driver_byte(retval) == DRIVER_ERROR)
 764                                 return SCSI_DH_DEV_TEMP_BUSY;
 765                 } else {
 766                         sdev_printk(KERN_INFO, sdev, "%s: stpg failed\n",
 767                                     ALUA_DH_NAME);
 768                         scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 769                 }
 770         }
 771         /* Retry RTPG */
 772         return SCSI_DH_RETRY;
 773 }
 774
 775 static void alua_rtpg_work(struct work_struct *work)
 776 {
 777         struct alua_port_group *pg =
 778                 container_of(work, struct alua_port_group, rtpg_work.work);
 779         struct scsi_device *sdev;
 780         LIST_HEAD(qdata_list);
 781         int err = SCSI_DH_OK;
 782         struct alua_queue_data *qdata, *tmp;
 783         unsigned long flags;
 784
 785         spin_lock_irqsave(&pg->lock, flags);
 786         sdev = pg->rtpg_sdev;
 787         if (!sdev) {
 788                 WARN_ON(pg->flags & ALUA_PG_RUN_RTPG);
 789                 WARN_ON(pg->flags & ALUA_PG_RUN_STPG);
 790                 spin_unlock_irqrestore(&pg->lock, flags);
 791                 kref_put(&pg->kref, release_port_group);
 792                 return;
 793         }
 794         pg->flags |= ALUA_PG_RUNNING;
 795         if (pg->flags & ALUA_PG_RUN_RTPG) {
 796                 int state = pg->state;
 797
 798                 pg->flags &= ~ALUA_PG_RUN_RTPG;
 799                 spin_unlock_irqrestore(&pg->lock, flags);
 800                 if (state == SCSI_ACCESS_STATE_TRANSITIONING) {
 801                         if (alua_tur(sdev) == SCSI_DH_RETRY) {
 802                                 spin_lock_irqsave(&pg->lock, flags);
 803                                 pg->flags &= ~ALUA_PG_RUNNING;
 804                                 pg->flags |= ALUA_PG_RUN_RTPG;
 805                                 spin_unlock_irqrestore(&pg->lock, flags);
 806                                 queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 807                                                    pg->interval * HZ);
 808                                 return;
 809                         }
 810                         /* Send RTPG on failure or if TUR indicates SUCCESS */
 811                 }
 812                 err = alua_rtpg(sdev, pg);
 813                 spin_lock_irqsave(&pg->lock, flags);
 814                 if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) {
 815                         pg->flags &= ~ALUA_PG_RUNNING;
 816                         pg->flags |= ALUA_PG_RUN_RTPG;
 817                         spin_unlock_irqrestore(&pg->lock, flags);
 818                         queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 819                                            pg->interval * HZ);
 820                         return;
 821                 }
 822                 if (err != SCSI_DH_OK)
 823                         pg->flags &= ~ALUA_PG_RUN_STPG;
 824         }
 825         if (pg->flags & ALUA_PG_RUN_STPG) {
 826                 pg->flags &= ~ALUA_PG_RUN_STPG;
 827                 spin_unlock_irqrestore(&pg->lock, flags);
 828                 err = alua_stpg(sdev, pg);
 829                 spin_lock_irqsave(&pg->lock, flags);
 830                 if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) {
 831                         pg->flags |= ALUA_PG_RUN_RTPG;
 832                         pg->interval = 0;
 833                         pg->flags &= ~ALUA_PG_RUNNING;
 834                         spin_unlock_irqrestore(&pg->lock, flags);
 835                         queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 836                                            pg->interval * HZ);
 837                         return;
 838                 }
 839         }
 840
 841         list_splice_init(&pg->rtpg_list, &qdata_list);
 842         pg->rtpg_sdev = NULL;
 843         spin_unlock_irqrestore(&pg->lock, flags);
 844
 845         list_for_each_entry_safe(qdata, tmp, &qdata_list, entry) {
 846                 list_del(&qdata->entry);
 847                 if (qdata->callback_fn)
 848                         qdata->callback_fn(qdata->callback_data, err);
 849                 kfree(qdata);
 850         }
 851         spin_lock_irqsave(&pg->lock, flags);
 852         pg->flags &= ~ALUA_PG_RUNNING;
 853         spin_unlock_irqrestore(&pg->lock, flags);
 854         scsi_device_put(sdev);
 855         kref_put(&pg->kref, release_port_group);
 856 }
 857
 858 /**
 859  * alua_rtpg_queue() - cause RTPG to be submitted asynchronously
 860  *
 861  * Returns true if and only if alua_rtpg_work() will be called asynchronously.
 862  * That function is responsible for calling @qdata->fn().
 863  */
 864 static bool alua_rtpg_queue(struct alua_port_group *pg,
 865                             struct scsi_device *sdev,
 866                             struct alua_queue_data *qdata, bool force)
 867 {
 868         int start_queue = 0;
 869         unsigned long flags;
 870         if (WARN_ON_ONCE(!pg) || scsi_device_get(sdev))
 871                 return false;
 872
 873         spin_lock_irqsave(&pg->lock, flags);
 874         if (qdata) {
 875                 list_add_tail(&qdata->entry, &pg->rtpg_list);
 876                 pg->flags |= ALUA_PG_RUN_STPG;
 877                 force = true;
 878         }
 879         if (pg->rtpg_sdev == NULL) {
 880                 pg->interval = 0;
 881                 pg->flags |= ALUA_PG_RUN_RTPG;
 882                 kref_get(&pg->kref);
 883                 pg->rtpg_sdev = sdev;
 884                 start_queue = 1;
 885         } else if (!(pg->flags & ALUA_PG_RUN_RTPG) && force) {
 886                 pg->flags |= ALUA_PG_RUN_RTPG;
 887                 /* Do not queue if the worker is already running */
 888                 if (!(pg->flags & ALUA_PG_RUNNING)) {
 889                         kref_get(&pg->kref);
 890                         start_queue = 1;
 891                 }
 892         }
 893
 894         spin_unlock_irqrestore(&pg->lock, flags);
 895
 896         if (start_queue) {
 897                 if (queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 898                                 msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS)))
 899                         sdev = NULL;
 900                 else
 901                         kref_put(&pg->kref, release_port_group);
 902         }
 903         if (sdev)
 904                 scsi_device_put(sdev);
 905
 906         return true;
 907 }
 908
 909 /*
 910  * alua_initialize - Initialize ALUA state
 911  * @sdev: the device to be initialized
 912  *
 913  * For the prep_fn to work correctly we have
 914  * to initialize the ALUA state for the device.
 915  */
 916 static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h)
 917 {
 918         int err = SCSI_DH_DEV_UNSUPP, tpgs;
 919
 920         mutex_lock(&h->init_mutex);
 921         tpgs = alua_check_tpgs(sdev);
 922         if (tpgs != TPGS_MODE_NONE)
 923                 err = alua_check_vpd(sdev, h, tpgs);
 924         h->init_error = err;
 925         mutex_unlock(&h->init_mutex);
 926         return err;
 927 }
 928 /*
 929  * alua_set_params - set/unset the optimize flag
 930  * @sdev: device on the path to be activated
 931  * params - parameters in the following format
 932  *      "no_of_params\0param1\0param2\0param3\0...\0"
 933  * For example, to set the flag pass the following parameters
 934  * from multipath.conf
 935  *     hardware_handler        "2 alua 1"
 936  */
 937 static int alua_set_params(struct scsi_device *sdev, const char *params)
 938 {
 939         struct alua_dh_data *h = sdev->handler_data;
 940         struct alua_port_group *pg = NULL;
 941         unsigned int optimize = 0, argc;
 942         const char *p = params;
 943         int result = SCSI_DH_OK;
 944         unsigned long flags;
 945
 946         if ((sscanf(params, "%u", &argc) != 1) || (argc != 1))
 947                 return -EINVAL;
 948
 949         while (*p++)
 950                 ;
 951         if ((sscanf(p, "%u", &optimize) != 1) || (optimize > 1))
 952                 return -EINVAL;
 953
 954         rcu_read_lock();
 955         pg = rcu_dereference(h->pg);
 956         if (!pg) {
 957                 rcu_read_unlock();
 958                 return -ENXIO;
 959         }
 960         spin_lock_irqsave(&pg->lock, flags);
 961         if (optimize)
 962                 pg->flags |= ALUA_OPTIMIZE_STPG;
 963         else
 964                 pg->flags &= ~ALUA_OPTIMIZE_STPG;
 965         spin_unlock_irqrestore(&pg->lock, flags);
 966         rcu_read_unlock();
 967
 968         return result;
 969 }
 970
 971 /*
 972  * alua_activate - activate a path
 973  * @sdev: device on the path to be activated
 974  *
 975  * We're currently switching the port group to be activated only and
 976  * let the array figure out the rest.
 977  * There may be other arrays which require us to switch all port groups
 978  * based on a certain policy. But until we actually encounter them it
 979  * should be okay.
 980  */
 981 static int alua_activate(struct scsi_device *sdev,
 982                         activate_complete fn, void *data)
 983 {
 984         struct alua_dh_data *h = sdev->handler_data;
 985         int err = SCSI_DH_OK;
 986         struct alua_queue_data *qdata;
 987         struct alua_port_group *pg;
 988
 989         qdata = kzalloc(sizeof(*qdata), GFP_KERNEL);
 990         if (!qdata) {
 991                 err = SCSI_DH_RES_TEMP_UNAVAIL;
 992                 goto out;
 993         }
 994         qdata->callback_fn = fn;
 995         qdata->callback_data = data;
 996
 997         mutex_lock(&h->init_mutex);
 998         rcu_read_lock();
 999         pg = rcu_dereference(h->pg);
1000         if (!pg || !kref_get_unless_zero(&pg->kref)) {
1001                 rcu_read_unlock();
1002                 kfree(qdata);
1003                 err = h->init_error;
1004                 mutex_unlock(&h->init_mutex);
1005                 goto out;
1006         }
1007         rcu_read_unlock();
1008         mutex_unlock(&h->init_mutex);
1009
1010         if (alua_rtpg_queue(pg, sdev, qdata, true))
1011                 fn = NULL;
1012         else
1013                 err = SCSI_DH_DEV_OFFLINED;
1014         kref_put(&pg->kref, release_port_group);
1015 out:
1016         if (fn)
1017                 fn(data, err);
1018         return 0;
1019 }
1020
1021 /*
1022  * alua_check - check path status
1023  * @sdev: device on the path to be checked
1024  *
1025  * Check the device status
1026  */
1027 static void alua_check(struct scsi_device *sdev, bool force)
1028 {
1029         struct alua_dh_data *h = sdev->handler_data;
1030         struct alua_port_group *pg;
1031
1032         rcu_read_lock();
1033         pg = rcu_dereference(h->pg);
1034         if (!pg || !kref_get_unless_zero(&pg->kref)) {
1035                 rcu_read_unlock();
1036                 return;
1037         }
1038         rcu_read_unlock();
1039
1040         alua_rtpg_queue(pg, sdev, NULL, force);
1041         kref_put(&pg->kref, release_port_group);
1042 }
1043
1044 /*
1045  * alua_prep_fn - request callback
1046  *
1047  * Fail I/O to all paths not in state
1048  * active/optimized or active/non-optimized.
1049  */
1050 static int alua_prep_fn(struct scsi_device *sdev, struct request *req)
1051 {
1052         struct alua_dh_data *h = sdev->handler_data;
1053         struct alua_port_group *pg;
1054         unsigned char state = SCSI_ACCESS_STATE_OPTIMAL;
1055         int ret = BLKPREP_OK;
1056
1057         rcu_read_lock();
1058         pg = rcu_dereference(h->pg);
1059         if (pg)
1060                 state = pg->state;
1061         rcu_read_unlock();
1062         if (state == SCSI_ACCESS_STATE_TRANSITIONING)
1063                 ret = BLKPREP_DEFER;
1064         else if (state != SCSI_ACCESS_STATE_OPTIMAL &&
1065                  state != SCSI_ACCESS_STATE_ACTIVE &&
1066                  state != SCSI_ACCESS_STATE_LBA) {
1067                 ret = BLKPREP_KILL;
1068                 req->rq_flags |= RQF_QUIET;
1069         }
1070         return ret;
1071
1072 }
1073
1074 static void alua_rescan(struct scsi_device *sdev)
1075 {
1076         struct alua_dh_data *h = sdev->handler_data;
1077
1078         alua_initialize(sdev, h);
1079 }
1080
1081 /*
1082  * alua_bus_attach - Attach device handler
1083  * @sdev: device to be attached to
1084  */
1085 static int alua_bus_attach(struct scsi_device *sdev)
1086 {
1087         struct alua_dh_data *h;
1088         int err;
1089
1090         h = kzalloc(sizeof(*h) , GFP_KERNEL);
1091         if (!h)
1092                 return SCSI_DH_NOMEM;
1093         spin_lock_init(&h->pg_lock);
1094         rcu_assign_pointer(h->pg, NULL);
1095         h->init_error = SCSI_DH_OK;
1096         h->sdev = sdev;
1097         INIT_LIST_HEAD(&h->node);
1098
1099         mutex_init(&h->init_mutex);
1100         err = alua_initialize(sdev, h);
1101         if (err != SCSI_DH_OK && err != SCSI_DH_DEV_OFFLINED)
1102                 goto failed;
1103
1104         sdev->handler_data = h;
1105         return SCSI_DH_OK;
1106 failed:
1107         kfree(h);
1108         return err;
1109 }
1110
1111 /*
1112  * alua_bus_detach - Detach device handler
1113  * @sdev: device to be detached from
1114  */
1115 static void alua_bus_detach(struct scsi_device *sdev)
1116 {
1117         struct alua_dh_data *h = sdev->handler_data;
1118         struct alua_port_group *pg;
1119
1120         spin_lock(&h->pg_lock);
1121         pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock));
1122         rcu_assign_pointer(h->pg, NULL);
1123         h->sdev = NULL;
1124         spin_unlock(&h->pg_lock);
1125         if (pg) {
1126                 spin_lock_irq(&pg->lock);
1127                 list_del_rcu(&h->node);
1128                 spin_unlock_irq(&pg->lock);
1129                 kref_put(&pg->kref, release_port_group);
1130         }
1131         sdev->handler_data = NULL;
1132         kfree(h);
1133 }
1134
1135 static struct scsi_device_handler alua_dh = {
1136         .name = ALUA_DH_NAME,
1137         .module = THIS_MODULE,
1138         .attach = alua_bus_attach,
1139         .detach = alua_bus_detach,
1140         .prep_fn = alua_prep_fn,
1141         .check_sense = alua_check_sense,
1142         .activate = alua_activate,
1143         .rescan = alua_rescan,
1144         .set_params = alua_set_params,
1145 };
1146
1147 static int __init alua_init(void)
1148 {
1149         int r;
1150
1151         kaluad_wq = alloc_workqueue("kaluad", WQ_MEM_RECLAIM, 0);
1152         if (!kaluad_wq) {
1153                 /* Temporary failure, bypass */
1154                 return SCSI_DH_DEV_TEMP_BUSY;
1155         }
1156
1157         r = scsi_register_device_handler(&alua_dh);
1158         if (r != 0) {
1159                 printk(KERN_ERR "%s: Failed to register scsi device handler",
1160                         ALUA_DH_NAME);
1161                 destroy_workqueue(kaluad_wq);
1162         }
1163         return r;
1164 }
1165
1166 static void __exit alua_exit(void)
1167 {
1168         scsi_unregister_device_handler(&alua_dh);
1169         destroy_workqueue(kaluad_wq);
1170 }
1171
1172 module_init(alua_init);
1173 module_exit(alua_exit);
1174
1175 MODULE_DESCRIPTION("DM Multipath ALUA support");
1176 MODULE_AUTHOR("Hannes Reinecke <hare@suse.de>");
1177 MODULE_LICENSE("GPL");
1178 MODULE_VERSION(ALUA_DH_VER);