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_dbg.h>
  28 #include <scsi/scsi_eh.h>
  29 #include <scsi/scsi_dh.h>
  30
  31 #define ALUA_DH_NAME "alua"
  32 #define ALUA_DH_VER "1.3"
  33
  34 #define TPGS_STATE_OPTIMIZED            0x0
  35 #define TPGS_STATE_NONOPTIMIZED         0x1
  36 #define TPGS_STATE_STANDBY              0x2
  37 #define TPGS_STATE_UNAVAILABLE          0x3
  38 #define TPGS_STATE_LBA_DEPENDENT        0x4
  39 #define TPGS_STATE_OFFLINE              0xe
  40 #define TPGS_STATE_TRANSITIONING        0xf
  41
  42 #define TPGS_SUPPORT_NONE               0x00
  43 #define TPGS_SUPPORT_OPTIMIZED          0x01
  44 #define TPGS_SUPPORT_NONOPTIMIZED       0x02
  45 #define TPGS_SUPPORT_STANDBY            0x04
  46 #define TPGS_SUPPORT_UNAVAILABLE        0x08
  47 #define TPGS_SUPPORT_LBA_DEPENDENT      0x10
  48 #define TPGS_SUPPORT_OFFLINE            0x40
  49 #define TPGS_SUPPORT_TRANSITION         0x80
  50
  51 #define RTPG_FMT_MASK                   0x70
  52 #define RTPG_FMT_EXT_HDR                0x10
  53
  54 #define TPGS_MODE_UNINITIALIZED          -1
  55 #define TPGS_MODE_NONE                  0x0
  56 #define TPGS_MODE_IMPLICIT              0x1
  57 #define TPGS_MODE_EXPLICIT              0x2
  58
  59 #define ALUA_INQUIRY_SIZE               36
  60 #define ALUA_FAILOVER_TIMEOUT           60
  61 #define ALUA_FAILOVER_RETRIES           5
  62
  63 /* device handler flags */
  64 #define ALUA_OPTIMIZE_STPG              1
  65 #define ALUA_RTPG_EXT_HDR_UNSUPP        2
  66
  67 struct alua_dh_data {
  68         int                     group_id;
  69         int                     rel_port;
  70         int                     tpgs;
  71         int                     state;
  72         int                     pref;
  73         unsigned                flags; /* used for optimizing STPG */
  74         unsigned char           inq[ALUA_INQUIRY_SIZE];
  75         unsigned char           *buff;
  76         int                     bufflen;
  77         unsigned char           transition_tmo;
  78         unsigned char           sense[SCSI_SENSE_BUFFERSIZE];
  79         struct scsi_device      *sdev;
  80         activate_complete       callback_fn;
  81         void                    *callback_data;
  82 };
  83
  84 #define ALUA_POLICY_SWITCH_CURRENT      0
  85 #define ALUA_POLICY_SWITCH_ALL          1
  86
  87 static char print_alua_state(int);
  88
  89 static int realloc_buffer(struct alua_dh_data *h, unsigned len)
  90 {
  91         if (h->buff && h->buff != h->inq)
  92                 kfree(h->buff);
  93
  94         h->buff = kmalloc(len, GFP_NOIO);
  95         if (!h->buff) {
  96                 h->buff = h->inq;
  97                 h->bufflen = ALUA_INQUIRY_SIZE;
  98                 return 1;
  99         }
 100         h->bufflen = len;
 101         return 0;
 102 }
 103
 104 static struct request *get_alua_req(struct scsi_device *sdev,
 105                                     void *buffer, unsigned buflen, int rw)
 106 {
 107         struct request *rq;
 108         struct request_queue *q = sdev->request_queue;
 109
 110         rq = blk_get_request(q, rw, GFP_NOIO);
 111
 112         if (IS_ERR(rq)) {
 113                 sdev_printk(KERN_INFO, sdev,
 114                             "%s: blk_get_request failed\n", __func__);
 115                 return NULL;
 116         }
 117         blk_rq_set_block_pc(rq);
 118
 119         if (buflen && blk_rq_map_kern(q, rq, buffer, buflen, GFP_NOIO)) {
 120                 blk_put_request(rq);
 121                 sdev_printk(KERN_INFO, sdev,
 122                             "%s: blk_rq_map_kern failed\n", __func__);
 123                 return NULL;
 124         }
 125
 126         rq->cmd_flags |= REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
 127                          REQ_FAILFAST_DRIVER;
 128         rq->retries = ALUA_FAILOVER_RETRIES;
 129         rq->timeout = ALUA_FAILOVER_TIMEOUT * HZ;
 130
 131         return rq;
 132 }
 133
 134 /*
 135  * submit_rtpg - Issue a REPORT TARGET GROUP STATES command
 136  * @sdev: sdev the command should be sent to
 137  */
 138 static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
 139 {
 140         struct request *rq;
 141         int err = 0;
 142
 143         rq = get_alua_req(sdev, h->buff, h->bufflen, READ);
 144         if (!rq) {
 145                 err = DRIVER_BUSY << 24;
 146                 goto done;
 147         }
 148
 149         /* Prepare the command. */
 150         rq->cmd[0] = MAINTENANCE_IN;
 151         if (!(h->flags & ALUA_RTPG_EXT_HDR_UNSUPP))
 152                 rq->cmd[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
 153         else
 154                 rq->cmd[1] = MI_REPORT_TARGET_PGS;
 155         put_unaligned_be32(h->bufflen, &rq->cmd[6]);
 156         rq->cmd_len = COMMAND_SIZE(MAINTENANCE_IN);
 157
 158         rq->sense = h->sense;
 159         memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
 160         rq->sense_len = 0;
 161
 162         blk_execute_rq(rq->q, NULL, rq, 1);
 163         if (rq->errors)
 164                 err = rq->errors;
 165         blk_put_request(rq);
 166 done:
 167         return err;
 168 }
 169
 170 /*
 171  * stpg_endio - Evaluate SET TARGET GROUP STATES
 172  * @sdev: the device to be evaluated
 173  * @state: the new target group state
 174  *
 175  * Evaluate a SET TARGET GROUP STATES command response.
 176  */
 177 static void stpg_endio(struct request *req, int error)
 178 {
 179         struct alua_dh_data *h = req->end_io_data;
 180         struct scsi_sense_hdr sense_hdr;
 181         unsigned err = SCSI_DH_OK;
 182
 183         if (host_byte(req->errors) != DID_OK ||
 184             msg_byte(req->errors) != COMMAND_COMPLETE) {
 185                 err = SCSI_DH_IO;
 186                 goto done;
 187         }
 188
 189         if (scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
 190                                  &sense_hdr)) {
 191                 if (sense_hdr.sense_key == NOT_READY &&
 192                     sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) {
 193                         /* ALUA state transition already in progress */
 194                         err = SCSI_DH_OK;
 195                         goto done;
 196                 }
 197                 if (sense_hdr.sense_key == UNIT_ATTENTION) {
 198                         err = SCSI_DH_RETRY;
 199                         goto done;
 200                 }
 201                 sdev_printk(KERN_INFO, h->sdev, "%s: stpg failed\n",
 202                             ALUA_DH_NAME);
 203                 scsi_print_sense_hdr(h->sdev, ALUA_DH_NAME, &sense_hdr);
 204                 err = SCSI_DH_IO;
 205         } else if (error)
 206                 err = SCSI_DH_IO;
 207
 208         if (err == SCSI_DH_OK) {
 209                 h->state = TPGS_STATE_OPTIMIZED;
 210                 sdev_printk(KERN_INFO, h->sdev,
 211                             "%s: port group %02x switched to state %c\n",
 212                             ALUA_DH_NAME, h->group_id,
 213                             print_alua_state(h->state));
 214         }
 215 done:
 216         req->end_io_data = NULL;
 217         __blk_put_request(req->q, req);
 218         if (h->callback_fn) {
 219                 h->callback_fn(h->callback_data, err);
 220                 h->callback_fn = h->callback_data = NULL;
 221         }
 222         return;
 223 }
 224
 225 /*
 226  * submit_stpg - Issue a SET TARGET GROUP STATES command
 227  *
 228  * Currently we're only setting the current target port group state
 229  * to 'active/optimized' and let the array firmware figure out
 230  * the states of the remaining groups.
 231  */
 232 static unsigned submit_stpg(struct alua_dh_data *h)
 233 {
 234         struct request *rq;
 235         int stpg_len = 8;
 236         struct scsi_device *sdev = h->sdev;
 237
 238         /* Prepare the data buffer */
 239         memset(h->buff, 0, stpg_len);
 240         h->buff[4] = TPGS_STATE_OPTIMIZED & 0x0f;
 241         put_unaligned_be16(h->group_id, &h->buff[6]);
 242
 243         rq = get_alua_req(sdev, h->buff, stpg_len, WRITE);
 244         if (!rq)
 245                 return SCSI_DH_RES_TEMP_UNAVAIL;
 246
 247         /* Prepare the command. */
 248         rq->cmd[0] = MAINTENANCE_OUT;
 249         rq->cmd[1] = MO_SET_TARGET_PGS;
 250         put_unaligned_be32(stpg_len, &rq->cmd[6]);
 251         rq->cmd_len = COMMAND_SIZE(MAINTENANCE_OUT);
 252
 253         rq->sense = h->sense;
 254         memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
 255         rq->sense_len = 0;
 256         rq->end_io_data = h;
 257
 258         blk_execute_rq_nowait(rq->q, NULL, rq, 1, stpg_endio);
 259         return SCSI_DH_OK;
 260 }
 261
 262 /*
 263  * alua_check_tpgs - Evaluate TPGS setting
 264  * @sdev: device to be checked
 265  *
 266  * Examine the TPGS setting of the sdev to find out if ALUA
 267  * is supported.
 268  */
 269 static int alua_check_tpgs(struct scsi_device *sdev)
 270 {
 271         int tpgs = TPGS_MODE_NONE;
 272
 273         /*
 274          * ALUA support for non-disk devices is fraught with
 275          * difficulties, so disable it for now.
 276          */
 277         if (sdev->type != TYPE_DISK) {
 278                 sdev_printk(KERN_INFO, sdev,
 279                             "%s: disable for non-disk devices\n",
 280                             ALUA_DH_NAME);
 281                 return tpgs;
 282         }
 283
 284         tpgs = scsi_device_tpgs(sdev);
 285         switch (tpgs) {
 286         case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT:
 287                 sdev_printk(KERN_INFO, sdev,
 288                             "%s: supports implicit and explicit TPGS\n",
 289                             ALUA_DH_NAME);
 290                 break;
 291         case TPGS_MODE_EXPLICIT:
 292                 sdev_printk(KERN_INFO, sdev, "%s: supports explicit TPGS\n",
 293                             ALUA_DH_NAME);
 294                 break;
 295         case TPGS_MODE_IMPLICIT:
 296                 sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n",
 297                             ALUA_DH_NAME);
 298                 break;
 299         case TPGS_MODE_NONE:
 300                 sdev_printk(KERN_INFO, sdev, "%s: not supported\n",
 301                             ALUA_DH_NAME);
 302                 break;
 303         default:
 304                 sdev_printk(KERN_INFO, sdev,
 305                             "%s: unsupported TPGS setting %d\n",
 306                             ALUA_DH_NAME, tpgs);
 307                 tpgs = TPGS_MODE_NONE;
 308                 break;
 309         }
 310
 311         return tpgs;
 312 }
 313
 314 /*
 315  * alua_check_vpd - Evaluate INQUIRY vpd page 0x83
 316  * @sdev: device to be checked
 317  *
 318  * Extract the relative target port and the target port group
 319  * descriptor from the list of identificators.
 320  */
 321 static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h)
 322 {
 323         unsigned char *d;
 324         unsigned char __rcu *vpd_pg83;
 325
 326         rcu_read_lock();
 327         if (!rcu_dereference(sdev->vpd_pg83)) {
 328                 rcu_read_unlock();
 329                 return SCSI_DH_DEV_UNSUPP;
 330         }
 331
 332         /*
 333          * Look for the correct descriptor.
 334          */
 335         vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
 336         d = vpd_pg83 + 4;
 337         while (d < vpd_pg83 + sdev->vpd_pg83_len) {
 338                 switch (d[1] & 0xf) {
 339                 case 0x4:
 340                         /* Relative target port */
 341                         h->rel_port = get_unaligned_be16(&d[6]);
 342                         break;
 343                 case 0x5:
 344                         /* Target port group */
 345                         h->group_id = get_unaligned_be16(&d[6]);
 346                         break;
 347                 default:
 348                         break;
 349                 }
 350                 d += d[3] + 4;
 351         }
 352         rcu_read_unlock();
 353
 354         if (h->group_id == -1) {
 355                 /*
 356                  * Internal error; TPGS supported but required
 357                  * VPD identification descriptors not present.
 358                  * Disable ALUA support
 359                  */
 360                 sdev_printk(KERN_INFO, sdev,
 361                             "%s: No target port descriptors found\n",
 362                             ALUA_DH_NAME);
 363                 h->state = TPGS_STATE_OPTIMIZED;
 364                 h->tpgs = TPGS_MODE_NONE;
 365                 return SCSI_DH_DEV_UNSUPP;
 366         }
 367         sdev_printk(KERN_INFO, sdev,
 368                     "%s: port group %02x rel port %02x\n",
 369                     ALUA_DH_NAME, h->group_id, h->rel_port);
 370
 371         return 0;
 372 }
 373
 374 static char print_alua_state(int state)
 375 {
 376         switch (state) {
 377         case TPGS_STATE_OPTIMIZED:
 378                 return 'A';
 379         case TPGS_STATE_NONOPTIMIZED:
 380                 return 'N';
 381         case TPGS_STATE_STANDBY:
 382                 return 'S';
 383         case TPGS_STATE_UNAVAILABLE:
 384                 return 'U';
 385         case TPGS_STATE_LBA_DEPENDENT:
 386                 return 'L';
 387         case TPGS_STATE_OFFLINE:
 388                 return 'O';
 389         case TPGS_STATE_TRANSITIONING:
 390                 return 'T';
 391         default:
 392                 return 'X';
 393         }
 394 }
 395
 396 static int alua_check_sense(struct scsi_device *sdev,
 397                             struct scsi_sense_hdr *sense_hdr)
 398 {
 399         switch (sense_hdr->sense_key) {
 400         case NOT_READY:
 401                 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a)
 402                         /*
 403                          * LUN Not Accessible - ALUA state transition
 404                          */
 405                         return ADD_TO_MLQUEUE;
 406                 break;
 407         case UNIT_ATTENTION:
 408                 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00)
 409                         /*
 410                          * Power On, Reset, or Bus Device Reset, just retry.
 411                          */
 412                         return ADD_TO_MLQUEUE;
 413                 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04)
 414                         /*
 415                          * Device internal reset
 416                          */
 417                         return ADD_TO_MLQUEUE;
 418                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01)
 419                         /*
 420                          * Mode Parameters Changed
 421                          */
 422                         return ADD_TO_MLQUEUE;
 423                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06)
 424                         /*
 425                          * ALUA state changed
 426                          */
 427                         return ADD_TO_MLQUEUE;
 428                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07)
 429                         /*
 430                          * Implicit ALUA state transition failed
 431                          */
 432                         return ADD_TO_MLQUEUE;
 433                 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03)
 434                         /*
 435                          * Inquiry data has changed
 436                          */
 437                         return ADD_TO_MLQUEUE;
 438                 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x0e)
 439                         /*
 440                          * REPORTED_LUNS_DATA_HAS_CHANGED is reported
 441                          * when switching controllers on targets like
 442                          * Intel Multi-Flex. We can just retry.
 443                          */
 444                         return ADD_TO_MLQUEUE;
 445                 break;
 446         }
 447
 448         return SCSI_RETURN_NOT_HANDLED;
 449 }
 450
 451 /*
 452  * alua_rtpg - Evaluate REPORT TARGET GROUP STATES
 453  * @sdev: the device to be evaluated.
 454  * @wait_for_transition: if nonzero, wait ALUA_FAILOVER_TIMEOUT seconds for device to exit transitioning state
 455  *
 456  * Evaluate the Target Port Group State.
 457  * Returns SCSI_DH_DEV_OFFLINED if the path is
 458  * found to be unusable.
 459  */
 460 static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h, int wait_for_transition)
 461 {
 462         struct scsi_sense_hdr sense_hdr;
 463         int len, k, off, valid_states = 0;
 464         unsigned char *ucp;
 465         unsigned err, retval;
 466         unsigned long expiry, interval = 0;
 467         unsigned int tpg_desc_tbl_off;
 468         unsigned char orig_transition_tmo;
 469
 470         if (!h->transition_tmo)
 471                 expiry = round_jiffies_up(jiffies + ALUA_FAILOVER_TIMEOUT * HZ);
 472         else
 473                 expiry = round_jiffies_up(jiffies + h->transition_tmo * HZ);
 474
 475  retry:
 476         retval = submit_rtpg(sdev, h);
 477         if (retval) {
 478                 if (!scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
 479                                           &sense_hdr)) {
 480                         sdev_printk(KERN_INFO, sdev,
 481                                     "%s: rtpg failed, result %d\n",
 482                                     ALUA_DH_NAME, retval);
 483                         if (driver_byte(retval) == DRIVER_BUSY)
 484                                 return SCSI_DH_DEV_TEMP_BUSY;
 485                         return SCSI_DH_IO;
 486                 }
 487
 488                 /*
 489                  * submit_rtpg() has failed on existing arrays
 490                  * when requesting extended header info, and
 491                  * the array doesn't support extended headers,
 492                  * even though it shouldn't according to T10.
 493                  * The retry without rtpg_ext_hdr_req set
 494                  * handles this.
 495                  */
 496                 if (!(h->flags & ALUA_RTPG_EXT_HDR_UNSUPP) &&
 497                     sense_hdr.sense_key == ILLEGAL_REQUEST &&
 498                     sense_hdr.asc == 0x24 && sense_hdr.ascq == 0) {
 499                         h->flags |= ALUA_RTPG_EXT_HDR_UNSUPP;
 500                         goto retry;
 501                 }
 502                 /*
 503                  * Retry on ALUA state transition or if any
 504                  * UNIT ATTENTION occurred.
 505                  */
 506                 if (sense_hdr.sense_key == NOT_READY &&
 507                     sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a)
 508                         err = SCSI_DH_RETRY;
 509                 else if (sense_hdr.sense_key == UNIT_ATTENTION)
 510                         err = SCSI_DH_RETRY;
 511                 if (err == SCSI_DH_RETRY && time_before(jiffies, expiry)) {
 512                         sdev_printk(KERN_ERR, sdev, "%s: rtpg retry\n",
 513                                     ALUA_DH_NAME);
 514                         scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 515                         goto retry;
 516                 }
 517                 sdev_printk(KERN_ERR, sdev, "%s: rtpg failed\n",
 518                             ALUA_DH_NAME);
 519                 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 520                 return SCSI_DH_IO;
 521         }
 522
 523         len = get_unaligned_be32(&h->buff[0]) + 4;
 524
 525         if (len > h->bufflen) {
 526                 /* Resubmit with the correct length */
 527                 if (realloc_buffer(h, len)) {
 528                         sdev_printk(KERN_WARNING, sdev,
 529                                     "%s: kmalloc buffer failed\n",__func__);
 530                         /* Temporary failure, bypass */
 531                         return SCSI_DH_DEV_TEMP_BUSY;
 532                 }
 533                 goto retry;
 534         }
 535
 536         orig_transition_tmo = h->transition_tmo;
 537         if ((h->buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR && h->buff[5] != 0)
 538                 h->transition_tmo = h->buff[5];
 539         else
 540                 h->transition_tmo = ALUA_FAILOVER_TIMEOUT;
 541
 542         if (wait_for_transition && (orig_transition_tmo != h->transition_tmo)) {
 543                 sdev_printk(KERN_INFO, sdev,
 544                             "%s: transition timeout set to %d seconds\n",
 545                             ALUA_DH_NAME, h->transition_tmo);
 546                 expiry = jiffies + h->transition_tmo * HZ;
 547         }
 548
 549         if ((h->buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR)
 550                 tpg_desc_tbl_off = 8;
 551         else
 552                 tpg_desc_tbl_off = 4;
 553
 554         for (k = tpg_desc_tbl_off, ucp = h->buff + tpg_desc_tbl_off;
 555              k < len;
 556              k += off, ucp += off) {
 557
 558                 if (h->group_id == get_unaligned_be16(&ucp[2])) {
 559                         h->state = ucp[0] & 0x0f;
 560                         h->pref = ucp[0] >> 7;
 561                         valid_states = ucp[1];
 562                 }
 563                 off = 8 + (ucp[7] * 4);
 564         }
 565
 566         sdev_printk(KERN_INFO, sdev,
 567                     "%s: port group %02x state %c %s supports %c%c%c%c%c%c%c\n",
 568                     ALUA_DH_NAME, h->group_id, print_alua_state(h->state),
 569                     h->pref ? "preferred" : "non-preferred",
 570                     valid_states&TPGS_SUPPORT_TRANSITION?'T':'t',
 571                     valid_states&TPGS_SUPPORT_OFFLINE?'O':'o',
 572                     valid_states&TPGS_SUPPORT_LBA_DEPENDENT?'L':'l',
 573                     valid_states&TPGS_SUPPORT_UNAVAILABLE?'U':'u',
 574                     valid_states&TPGS_SUPPORT_STANDBY?'S':'s',
 575                     valid_states&TPGS_SUPPORT_NONOPTIMIZED?'N':'n',
 576                     valid_states&TPGS_SUPPORT_OPTIMIZED?'A':'a');
 577
 578         switch (h->state) {
 579         case TPGS_STATE_TRANSITIONING:
 580                 if (wait_for_transition) {
 581                         if (time_before(jiffies, expiry)) {
 582                                 /* State transition, retry */
 583                                 interval += 2000;
 584                                 msleep(interval);
 585                                 goto retry;
 586                         }
 587                         err = SCSI_DH_RETRY;
 588                 } else {
 589                         err = SCSI_DH_OK;
 590                 }
 591
 592                 /* Transitioning time exceeded, set port to standby */
 593                 h->state = TPGS_STATE_STANDBY;
 594                 break;
 595         case TPGS_STATE_OFFLINE:
 596                 /* Path unusable */
 597                 err = SCSI_DH_DEV_OFFLINED;
 598                 break;
 599         default:
 600                 /* Useable path if active */
 601                 err = SCSI_DH_OK;
 602                 break;
 603         }
 604         return err;
 605 }
 606
 607 /*
 608  * alua_initialize - Initialize ALUA state
 609  * @sdev: the device to be initialized
 610  *
 611  * For the prep_fn to work correctly we have
 612  * to initialize the ALUA state for the device.
 613  */
 614 static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h)
 615 {
 616         int err = SCSI_DH_DEV_UNSUPP;
 617
 618         h->tpgs = alua_check_tpgs(sdev);
 619         if (h->tpgs == TPGS_MODE_NONE)
 620                 goto out;
 621
 622         err = alua_check_vpd(sdev, h);
 623         if (err != SCSI_DH_OK)
 624                 goto out;
 625
 626         err = alua_rtpg(sdev, h, 0);
 627         if (err != SCSI_DH_OK)
 628                 goto out;
 629
 630 out:
 631         return err;
 632 }
 633 /*
 634  * alua_set_params - set/unset the optimize flag
 635  * @sdev: device on the path to be activated
 636  * params - parameters in the following format
 637  *      "no_of_params\0param1\0param2\0param3\0...\0"
 638  * For example, to set the flag pass the following parameters
 639  * from multipath.conf
 640  *     hardware_handler        "2 alua 1"
 641  */
 642 static int alua_set_params(struct scsi_device *sdev, const char *params)
 643 {
 644         struct alua_dh_data *h = sdev->handler_data;
 645         unsigned int optimize = 0, argc;
 646         const char *p = params;
 647         int result = SCSI_DH_OK;
 648
 649         if ((sscanf(params, "%u", &argc) != 1) || (argc != 1))
 650                 return -EINVAL;
 651
 652         while (*p++)
 653                 ;
 654         if ((sscanf(p, "%u", &optimize) != 1) || (optimize > 1))
 655                 return -EINVAL;
 656
 657         if (optimize)
 658                 h->flags |= ALUA_OPTIMIZE_STPG;
 659         else
 660                 h->flags &= ~ALUA_OPTIMIZE_STPG;
 661
 662         return result;
 663 }
 664
 665 static uint optimize_stpg;
 666 module_param(optimize_stpg, uint, S_IRUGO|S_IWUSR);
 667 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.");
 668
 669 /*
 670  * alua_activate - activate a path
 671  * @sdev: device on the path to be activated
 672  *
 673  * We're currently switching the port group to be activated only and
 674  * let the array figure out the rest.
 675  * There may be other arrays which require us to switch all port groups
 676  * based on a certain policy. But until we actually encounter them it
 677  * should be okay.
 678  */
 679 static int alua_activate(struct scsi_device *sdev,
 680                         activate_complete fn, void *data)
 681 {
 682         struct alua_dh_data *h = sdev->handler_data;
 683         int err = SCSI_DH_OK;
 684         int stpg = 0;
 685
 686         err = alua_rtpg(sdev, h, 1);
 687         if (err != SCSI_DH_OK)
 688                 goto out;
 689
 690         if (optimize_stpg)
 691                 h->flags |= ALUA_OPTIMIZE_STPG;
 692
 693         if (h->tpgs & TPGS_MODE_EXPLICIT) {
 694                 switch (h->state) {
 695                 case TPGS_STATE_NONOPTIMIZED:
 696                         stpg = 1;
 697                         if ((h->flags & ALUA_OPTIMIZE_STPG) &&
 698                             (!h->pref) &&
 699                             (h->tpgs & TPGS_MODE_IMPLICIT))
 700                                 stpg = 0;
 701                         break;
 702                 case TPGS_STATE_STANDBY:
 703                 case TPGS_STATE_UNAVAILABLE:
 704                         stpg = 1;
 705                         break;
 706                 case TPGS_STATE_OFFLINE:
 707                         err = SCSI_DH_IO;
 708                         break;
 709                 case TPGS_STATE_TRANSITIONING:
 710                         err = SCSI_DH_RETRY;
 711                         break;
 712                 default:
 713                         break;
 714                 }
 715         }
 716
 717         if (stpg) {
 718                 h->callback_fn = fn;
 719                 h->callback_data = data;
 720                 err = submit_stpg(h);
 721                 if (err == SCSI_DH_OK)
 722                         return 0;
 723                 h->callback_fn = h->callback_data = NULL;
 724         }
 725
 726 out:
 727         if (fn)
 728                 fn(data, err);
 729         return 0;
 730 }
 731
 732 /*
 733  * alua_prep_fn - request callback
 734  *
 735  * Fail I/O to all paths not in state
 736  * active/optimized or active/non-optimized.
 737  */
 738 static int alua_prep_fn(struct scsi_device *sdev, struct request *req)
 739 {
 740         struct alua_dh_data *h = sdev->handler_data;
 741         int ret = BLKPREP_OK;
 742
 743         if (h->state == TPGS_STATE_TRANSITIONING)
 744                 ret = BLKPREP_DEFER;
 745         else if (h->state != TPGS_STATE_OPTIMIZED &&
 746                  h->state != TPGS_STATE_NONOPTIMIZED &&
 747                  h->state != TPGS_STATE_LBA_DEPENDENT) {
 748                 ret = BLKPREP_KILL;
 749                 req->cmd_flags |= REQ_QUIET;
 750         }
 751         return ret;
 752
 753 }
 754
 755 /*
 756  * alua_bus_attach - Attach device handler
 757  * @sdev: device to be attached to
 758  */
 759 static int alua_bus_attach(struct scsi_device *sdev)
 760 {
 761         struct alua_dh_data *h;
 762         int err;
 763
 764         h = kzalloc(sizeof(*h) , GFP_KERNEL);
 765         if (!h)
 766                 return -ENOMEM;
 767         h->tpgs = TPGS_MODE_UNINITIALIZED;
 768         h->state = TPGS_STATE_OPTIMIZED;
 769         h->group_id = -1;
 770         h->rel_port = -1;
 771         h->buff = h->inq;
 772         h->bufflen = ALUA_INQUIRY_SIZE;
 773         h->sdev = sdev;
 774
 775         err = alua_initialize(sdev, h);
 776         if (err != SCSI_DH_OK && err != SCSI_DH_DEV_OFFLINED)
 777                 goto failed;
 778
 779         sdev->handler_data = h;
 780         return 0;
 781 failed:
 782         kfree(h);
 783         return -EINVAL;
 784 }
 785
 786 /*
 787  * alua_bus_detach - Detach device handler
 788  * @sdev: device to be detached from
 789  */
 790 static void alua_bus_detach(struct scsi_device *sdev)
 791 {
 792         struct alua_dh_data *h = sdev->handler_data;
 793
 794         if (h->buff && h->inq != h->buff)
 795                 kfree(h->buff);
 796         sdev->handler_data = NULL;
 797         kfree(h);
 798 }
 799
 800 static struct scsi_device_handler alua_dh = {
 801         .name = ALUA_DH_NAME,
 802         .module = THIS_MODULE,
 803         .attach = alua_bus_attach,
 804         .detach = alua_bus_detach,
 805         .prep_fn = alua_prep_fn,
 806         .check_sense = alua_check_sense,
 807         .activate = alua_activate,
 808         .set_params = alua_set_params,
 809 };
 810
 811 static int __init alua_init(void)
 812 {
 813         int r;
 814
 815         r = scsi_register_device_handler(&alua_dh);
 816         if (r != 0)
 817                 printk(KERN_ERR "%s: Failed to register scsi device handler",
 818                         ALUA_DH_NAME);
 819         return r;
 820 }
 821
 822 static void __exit alua_exit(void)
 823 {
 824         scsi_unregister_device_handler(&alua_dh);
 825 }
 826
 827 module_init(alua_init);
 828 module_exit(alua_exit);
 829
 830 MODULE_DESCRIPTION("DM Multipath ALUA support");
 831 MODULE_AUTHOR("Hannes Reinecke <hare@suse.de>");
 832 MODULE_LICENSE("GPL");
 833 MODULE_VERSION(ALUA_DH_VER);