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 <scsi/scsi.h>
  26 #include <scsi/scsi_eh.h>
  27 #include <scsi/scsi_dh.h>
  28
  29 #define ALUA_DH_NAME "alua"
  30 #define ALUA_DH_VER "1.3"
  31
  32 #define TPGS_STATE_OPTIMIZED            0x0
  33 #define TPGS_STATE_NONOPTIMIZED         0x1
  34 #define TPGS_STATE_STANDBY              0x2
  35 #define TPGS_STATE_UNAVAILABLE          0x3
  36 #define TPGS_STATE_LBA_DEPENDENT        0x4
  37 #define TPGS_STATE_OFFLINE              0xe
  38 #define TPGS_STATE_TRANSITIONING        0xf
  39
  40 #define TPGS_SUPPORT_NONE               0x00
  41 #define TPGS_SUPPORT_OPTIMIZED          0x01
  42 #define TPGS_SUPPORT_NONOPTIMIZED       0x02
  43 #define TPGS_SUPPORT_STANDBY            0x04
  44 #define TPGS_SUPPORT_UNAVAILABLE        0x08
  45 #define TPGS_SUPPORT_LBA_DEPENDENT      0x10
  46 #define TPGS_SUPPORT_OFFLINE            0x40
  47 #define TPGS_SUPPORT_TRANSITION         0x80
  48
  49 #define TPGS_MODE_UNINITIALIZED          -1
  50 #define TPGS_MODE_NONE                  0x0
  51 #define TPGS_MODE_IMPLICIT              0x1
  52 #define TPGS_MODE_EXPLICIT              0x2
  53
  54 #define ALUA_INQUIRY_SIZE               36
  55 #define ALUA_FAILOVER_TIMEOUT           (60 * HZ)
  56 #define ALUA_FAILOVER_RETRIES           5
  57
  58 struct alua_dh_data {
  59         int                     group_id;
  60         int                     rel_port;
  61         int                     tpgs;
  62         int                     state;
  63         unsigned char           inq[ALUA_INQUIRY_SIZE];
  64         unsigned char           *buff;
  65         int                     bufflen;
  66         unsigned char           sense[SCSI_SENSE_BUFFERSIZE];
  67         int                     senselen;
  68         struct scsi_device      *sdev;
  69         activate_complete       callback_fn;
  70         void                    *callback_data;
  71 };
  72
  73 #define ALUA_POLICY_SWITCH_CURRENT      0
  74 #define ALUA_POLICY_SWITCH_ALL          1
  75
  76 static char print_alua_state(int);
  77 static int alua_check_sense(struct scsi_device *, struct scsi_sense_hdr *);
  78
  79 static inline struct alua_dh_data *get_alua_data(struct scsi_device *sdev)
  80 {
  81         struct scsi_dh_data *scsi_dh_data = sdev->scsi_dh_data;
  82         BUG_ON(scsi_dh_data == NULL);
  83         return ((struct alua_dh_data *) scsi_dh_data->buf);
  84 }
  85
  86 static int realloc_buffer(struct alua_dh_data *h, unsigned len)
  87 {
  88         if (h->buff && h->buff != h->inq)
  89                 kfree(h->buff);
  90
  91         h->buff = kmalloc(len, GFP_NOIO);
  92         if (!h->buff) {
  93                 h->buff = h->inq;
  94                 h->bufflen = ALUA_INQUIRY_SIZE;
  95                 return 1;
  96         }
  97         h->bufflen = len;
  98         return 0;
  99 }
 100
 101 static struct request *get_alua_req(struct scsi_device *sdev,
 102                                     void *buffer, unsigned buflen, int rw)
 103 {
 104         struct request *rq;
 105         struct request_queue *q = sdev->request_queue;
 106
 107         rq = blk_get_request(q, rw, GFP_NOIO);
 108
 109         if (!rq) {
 110                 sdev_printk(KERN_INFO, sdev,
 111                             "%s: blk_get_request failed\n", __func__);
 112                 return NULL;
 113         }
 114
 115         if (buflen && blk_rq_map_kern(q, rq, buffer, buflen, GFP_NOIO)) {
 116                 blk_put_request(rq);
 117                 sdev_printk(KERN_INFO, sdev,
 118                             "%s: blk_rq_map_kern failed\n", __func__);
 119                 return NULL;
 120         }
 121
 122         rq->cmd_type = REQ_TYPE_BLOCK_PC;
 123         rq->cmd_flags |= REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
 124                          REQ_FAILFAST_DRIVER;
 125         rq->retries = ALUA_FAILOVER_RETRIES;
 126         rq->timeout = ALUA_FAILOVER_TIMEOUT;
 127
 128         return rq;
 129 }
 130
 131 /*
 132  * submit_vpd_inquiry - Issue an INQUIRY VPD page 0x83 command
 133  * @sdev: sdev the command should be sent to
 134  */
 135 static int submit_vpd_inquiry(struct scsi_device *sdev, struct alua_dh_data *h)
 136 {
 137         struct request *rq;
 138         int err = SCSI_DH_RES_TEMP_UNAVAIL;
 139
 140         rq = get_alua_req(sdev, h->buff, h->bufflen, READ);
 141         if (!rq)
 142                 goto done;
 143
 144         /* Prepare the command. */
 145         rq->cmd[0] = INQUIRY;
 146         rq->cmd[1] = 1;
 147         rq->cmd[2] = 0x83;
 148         rq->cmd[4] = h->bufflen;
 149         rq->cmd_len = COMMAND_SIZE(INQUIRY);
 150
 151         rq->sense = h->sense;
 152         memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
 153         rq->sense_len = h->senselen = 0;
 154
 155         err = blk_execute_rq(rq->q, NULL, rq, 1);
 156         if (err == -EIO) {
 157                 sdev_printk(KERN_INFO, sdev,
 158                             "%s: evpd inquiry failed with %x\n",
 159                             ALUA_DH_NAME, rq->errors);
 160                 h->senselen = rq->sense_len;
 161                 err = SCSI_DH_IO;
 162         }
 163         blk_put_request(rq);
 164 done:
 165         return err;
 166 }
 167
 168 /*
 169  * submit_rtpg - Issue a REPORT TARGET GROUP STATES command
 170  * @sdev: sdev the command should be sent to
 171  */
 172 static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
 173 {
 174         struct request *rq;
 175         int err = SCSI_DH_RES_TEMP_UNAVAIL;
 176
 177         rq = get_alua_req(sdev, h->buff, h->bufflen, READ);
 178         if (!rq)
 179                 goto done;
 180
 181         /* Prepare the command. */
 182         rq->cmd[0] = MAINTENANCE_IN;
 183         rq->cmd[1] = MI_REPORT_TARGET_PGS;
 184         rq->cmd[6] = (h->bufflen >> 24) & 0xff;
 185         rq->cmd[7] = (h->bufflen >> 16) & 0xff;
 186         rq->cmd[8] = (h->bufflen >>  8) & 0xff;
 187         rq->cmd[9] = h->bufflen & 0xff;
 188         rq->cmd_len = COMMAND_SIZE(MAINTENANCE_IN);
 189
 190         rq->sense = h->sense;
 191         memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
 192         rq->sense_len = h->senselen = 0;
 193
 194         err = blk_execute_rq(rq->q, NULL, rq, 1);
 195         if (err == -EIO) {
 196                 sdev_printk(KERN_INFO, sdev,
 197                             "%s: rtpg failed with %x\n",
 198                             ALUA_DH_NAME, rq->errors);
 199                 h->senselen = rq->sense_len;
 200                 err = SCSI_DH_IO;
 201         }
 202         blk_put_request(rq);
 203 done:
 204         return err;
 205 }
 206
 207 /*
 208  * alua_stpg - Evaluate SET TARGET GROUP STATES
 209  * @sdev: the device to be evaluated
 210  * @state: the new target group state
 211  *
 212  * Send a SET TARGET GROUP STATES command to the device.
 213  * We only have to test here if we should resubmit the command;
 214  * any other error is assumed as a failure.
 215  */
 216 static void stpg_endio(struct request *req, int error)
 217 {
 218         struct alua_dh_data *h = req->end_io_data;
 219         struct scsi_sense_hdr sense_hdr;
 220         unsigned err = SCSI_DH_OK;
 221
 222         if (error || host_byte(req->errors) != DID_OK ||
 223                         msg_byte(req->errors) != COMMAND_COMPLETE) {
 224                 err = SCSI_DH_IO;
 225                 goto done;
 226         }
 227
 228         if (h->senselen > 0) {
 229                 err = scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
 230                                            &sense_hdr);
 231                 if (!err) {
 232                         err = SCSI_DH_IO;
 233                         goto done;
 234                 }
 235                 err = alua_check_sense(h->sdev, &sense_hdr);
 236                 if (err == ADD_TO_MLQUEUE) {
 237                         err = SCSI_DH_RETRY;
 238                         goto done;
 239                 }
 240                 sdev_printk(KERN_INFO, h->sdev,
 241                             "%s: stpg sense code: %02x/%02x/%02x\n",
 242                             ALUA_DH_NAME, sense_hdr.sense_key,
 243                             sense_hdr.asc, sense_hdr.ascq);
 244                 err = SCSI_DH_IO;
 245         }
 246         if (err == SCSI_DH_OK) {
 247                 h->state = TPGS_STATE_OPTIMIZED;
 248                 sdev_printk(KERN_INFO, h->sdev,
 249                             "%s: port group %02x switched to state %c\n",
 250                             ALUA_DH_NAME, h->group_id,
 251                             print_alua_state(h->state));
 252         }
 253 done:
 254         req->end_io_data = NULL;
 255         __blk_put_request(req->q, req);
 256         if (h->callback_fn) {
 257                 h->callback_fn(h->callback_data, err);
 258                 h->callback_fn = h->callback_data = NULL;
 259         }
 260         return;
 261 }
 262
 263 /*
 264  * submit_stpg - Issue a SET TARGET GROUP STATES command
 265  *
 266  * Currently we're only setting the current target port group state
 267  * to 'active/optimized' and let the array firmware figure out
 268  * the states of the remaining groups.
 269  */
 270 static unsigned submit_stpg(struct alua_dh_data *h)
 271 {
 272         struct request *rq;
 273         int stpg_len = 8;
 274         struct scsi_device *sdev = h->sdev;
 275
 276         /* Prepare the data buffer */
 277         memset(h->buff, 0, stpg_len);
 278         h->buff[4] = TPGS_STATE_OPTIMIZED & 0x0f;
 279         h->buff[6] = (h->group_id >> 8) & 0xff;
 280         h->buff[7] = h->group_id & 0xff;
 281
 282         rq = get_alua_req(sdev, h->buff, stpg_len, WRITE);
 283         if (!rq)
 284                 return SCSI_DH_RES_TEMP_UNAVAIL;
 285
 286         /* Prepare the command. */
 287         rq->cmd[0] = MAINTENANCE_OUT;
 288         rq->cmd[1] = MO_SET_TARGET_PGS;
 289         rq->cmd[6] = (stpg_len >> 24) & 0xff;
 290         rq->cmd[7] = (stpg_len >> 16) & 0xff;
 291         rq->cmd[8] = (stpg_len >>  8) & 0xff;
 292         rq->cmd[9] = stpg_len & 0xff;
 293         rq->cmd_len = COMMAND_SIZE(MAINTENANCE_OUT);
 294
 295         rq->sense = h->sense;
 296         memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
 297         rq->sense_len = h->senselen = 0;
 298         rq->end_io_data = h;
 299
 300         blk_execute_rq_nowait(rq->q, NULL, rq, 1, stpg_endio);
 301         return SCSI_DH_OK;
 302 }
 303
 304 /*
 305  * alua_check_tpgs - Evaluate TPGS setting
 306  * @sdev: device to be checked
 307  *
 308  * Examine the TPGS setting of the sdev to find out if ALUA
 309  * is supported.
 310  */
 311 static int alua_check_tpgs(struct scsi_device *sdev, struct alua_dh_data *h)
 312 {
 313         int err = SCSI_DH_OK;
 314
 315         h->tpgs = scsi_device_tpgs(sdev);
 316         switch (h->tpgs) {
 317         case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT:
 318                 sdev_printk(KERN_INFO, sdev,
 319                             "%s: supports implicit and explicit TPGS\n",
 320                             ALUA_DH_NAME);
 321                 break;
 322         case TPGS_MODE_EXPLICIT:
 323                 sdev_printk(KERN_INFO, sdev, "%s: supports explicit TPGS\n",
 324                             ALUA_DH_NAME);
 325                 break;
 326         case TPGS_MODE_IMPLICIT:
 327                 sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n",
 328                             ALUA_DH_NAME);
 329                 break;
 330         default:
 331                 h->tpgs = TPGS_MODE_NONE;
 332                 sdev_printk(KERN_INFO, sdev, "%s: not supported\n",
 333                             ALUA_DH_NAME);
 334                 err = SCSI_DH_DEV_UNSUPP;
 335                 break;
 336         }
 337
 338         return err;
 339 }
 340
 341 /*
 342  * alua_vpd_inquiry - Evaluate INQUIRY vpd page 0x83
 343  * @sdev: device to be checked
 344  *
 345  * Extract the relative target port and the target port group
 346  * descriptor from the list of identificators.
 347  */
 348 static int alua_vpd_inquiry(struct scsi_device *sdev, struct alua_dh_data *h)
 349 {
 350         int len;
 351         unsigned err;
 352         unsigned char *d;
 353
 354  retry:
 355         err = submit_vpd_inquiry(sdev, h);
 356
 357         if (err != SCSI_DH_OK)
 358                 return err;
 359
 360         /* Check if vpd page exceeds initial buffer */
 361         len = (h->buff[2] << 8) + h->buff[3] + 4;
 362         if (len > h->bufflen) {
 363                 /* Resubmit with the correct length */
 364                 if (realloc_buffer(h, len)) {
 365                         sdev_printk(KERN_WARNING, sdev,
 366                                     "%s: kmalloc buffer failed\n",
 367                                     ALUA_DH_NAME);
 368                         /* Temporary failure, bypass */
 369                         return SCSI_DH_DEV_TEMP_BUSY;
 370                 }
 371                 goto retry;
 372         }
 373
 374         /*
 375          * Now look for the correct descriptor.
 376          */
 377         d = h->buff + 4;
 378         while (d < h->buff + len) {
 379                 switch (d[1] & 0xf) {
 380                 case 0x4:
 381                         /* Relative target port */
 382                         h->rel_port = (d[6] << 8) + d[7];
 383                         break;
 384                 case 0x5:
 385                         /* Target port group */
 386                         h->group_id = (d[6] << 8) + d[7];
 387                         break;
 388                 default:
 389                         break;
 390                 }
 391                 d += d[3] + 4;
 392         }
 393
 394         if (h->group_id == -1) {
 395                 /*
 396                  * Internal error; TPGS supported but required
 397                  * VPD identification descriptors not present.
 398                  * Disable ALUA support
 399                  */
 400                 sdev_printk(KERN_INFO, sdev,
 401                             "%s: No target port descriptors found\n",
 402                             ALUA_DH_NAME);
 403                 h->state = TPGS_STATE_OPTIMIZED;
 404                 h->tpgs = TPGS_MODE_NONE;
 405                 err = SCSI_DH_DEV_UNSUPP;
 406         } else {
 407                 sdev_printk(KERN_INFO, sdev,
 408                             "%s: port group %02x rel port %02x\n",
 409                             ALUA_DH_NAME, h->group_id, h->rel_port);
 410         }
 411
 412         return err;
 413 }
 414
 415 static char print_alua_state(int state)
 416 {
 417         switch (state) {
 418         case TPGS_STATE_OPTIMIZED:
 419                 return 'A';
 420         case TPGS_STATE_NONOPTIMIZED:
 421                 return 'N';
 422         case TPGS_STATE_STANDBY:
 423                 return 'S';
 424         case TPGS_STATE_UNAVAILABLE:
 425                 return 'U';
 426         case TPGS_STATE_LBA_DEPENDENT:
 427                 return 'L';
 428         case TPGS_STATE_OFFLINE:
 429                 return 'O';
 430         case TPGS_STATE_TRANSITIONING:
 431                 return 'T';
 432         default:
 433                 return 'X';
 434         }
 435 }
 436
 437 static int alua_check_sense(struct scsi_device *sdev,
 438                             struct scsi_sense_hdr *sense_hdr)
 439 {
 440         switch (sense_hdr->sense_key) {
 441         case NOT_READY:
 442                 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a)
 443                         /*
 444                          * LUN Not Accessible - ALUA state transition
 445                          */
 446                         return ADD_TO_MLQUEUE;
 447                 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0b)
 448                         /*
 449                          * LUN Not Accessible -- Target port in standby state
 450                          */
 451                         return SUCCESS;
 452                 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0c)
 453                         /*
 454                          * LUN Not Accessible -- Target port in unavailable state
 455                          */
 456                         return SUCCESS;
 457                 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x12)
 458                         /*
 459                          * LUN Not Ready -- Offline
 460                          */
 461                         return SUCCESS;
 462                 break;
 463         case UNIT_ATTENTION:
 464                 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00)
 465                         /*
 466                          * Power On, Reset, or Bus Device Reset, just retry.
 467                          */
 468                         return ADD_TO_MLQUEUE;
 469                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01)
 470                         /*
 471                          * Mode Parameters Changed
 472                          */
 473                         return ADD_TO_MLQUEUE;
 474                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06)
 475                         /*
 476                          * ALUA state changed
 477                          */
 478                         return ADD_TO_MLQUEUE;
 479                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07)
 480                         /*
 481                          * Implicit ALUA state transition failed
 482                          */
 483                         return ADD_TO_MLQUEUE;
 484                 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03)
 485                         /*
 486                          * Inquiry data has changed
 487                          */
 488                         return ADD_TO_MLQUEUE;
 489                 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x0e)
 490                         /*
 491                          * REPORTED_LUNS_DATA_HAS_CHANGED is reported
 492                          * when switching controllers on targets like
 493                          * Intel Multi-Flex. We can just retry.
 494                          */
 495                         return ADD_TO_MLQUEUE;
 496                 break;
 497         }
 498
 499         return SCSI_RETURN_NOT_HANDLED;
 500 }
 501
 502 /*
 503  * alua_rtpg - Evaluate REPORT TARGET GROUP STATES
 504  * @sdev: the device to be evaluated.
 505  *
 506  * Evaluate the Target Port Group State.
 507  * Returns SCSI_DH_DEV_OFFLINED if the path is
 508  * found to be unusable.
 509  */
 510 static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
 511 {
 512         struct scsi_sense_hdr sense_hdr;
 513         int len, k, off, valid_states = 0;
 514         unsigned char *ucp;
 515         unsigned err;
 516         unsigned long expiry, interval = 1000;
 517
 518         expiry = round_jiffies_up(jiffies + ALUA_FAILOVER_TIMEOUT);
 519  retry:
 520         err = submit_rtpg(sdev, h);
 521
 522         if (err == SCSI_DH_IO && h->senselen > 0) {
 523                 err = scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
 524                                            &sense_hdr);
 525                 if (!err)
 526                         return SCSI_DH_IO;
 527
 528                 err = alua_check_sense(sdev, &sense_hdr);
 529                 if (err == ADD_TO_MLQUEUE && time_before(jiffies, expiry))
 530                         goto retry;
 531                 sdev_printk(KERN_INFO, sdev,
 532                             "%s: rtpg sense code %02x/%02x/%02x\n",
 533                             ALUA_DH_NAME, sense_hdr.sense_key,
 534                             sense_hdr.asc, sense_hdr.ascq);
 535                 err = SCSI_DH_IO;
 536         }
 537         if (err != SCSI_DH_OK)
 538                 return err;
 539
 540         len = (h->buff[0] << 24) + (h->buff[1] << 16) +
 541                 (h->buff[2] << 8) + h->buff[3] + 4;
 542
 543         if (len > h->bufflen) {
 544                 /* Resubmit with the correct length */
 545                 if (realloc_buffer(h, len)) {
 546                         sdev_printk(KERN_WARNING, sdev,
 547                                     "%s: kmalloc buffer failed\n",__func__);
 548                         /* Temporary failure, bypass */
 549                         return SCSI_DH_DEV_TEMP_BUSY;
 550                 }
 551                 goto retry;
 552         }
 553
 554         for (k = 4, ucp = h->buff + 4; k < len; k += off, ucp += off) {
 555                 if (h->group_id == (ucp[2] << 8) + ucp[3]) {
 556                         h->state = ucp[0] & 0x0f;
 557                         valid_states = ucp[1];
 558                 }
 559                 off = 8 + (ucp[7] * 4);
 560         }
 561
 562         sdev_printk(KERN_INFO, sdev,
 563                     "%s: port group %02x state %c supports %c%c%c%c%c%c%c\n",
 564                     ALUA_DH_NAME, h->group_id, print_alua_state(h->state),
 565                     valid_states&TPGS_SUPPORT_TRANSITION?'T':'t',
 566                     valid_states&TPGS_SUPPORT_OFFLINE?'O':'o',
 567                     valid_states&TPGS_SUPPORT_LBA_DEPENDENT?'L':'l',
 568                     valid_states&TPGS_SUPPORT_UNAVAILABLE?'U':'u',
 569                     valid_states&TPGS_SUPPORT_STANDBY?'S':'s',
 570                     valid_states&TPGS_SUPPORT_NONOPTIMIZED?'N':'n',
 571                     valid_states&TPGS_SUPPORT_OPTIMIZED?'A':'a');
 572
 573         switch (h->state) {
 574         case TPGS_STATE_TRANSITIONING:
 575                 if (time_before(jiffies, expiry)) {
 576                         /* State transition, retry */
 577                         interval *= 2;
 578                         msleep(interval);
 579                         goto retry;
 580                 }
 581                 /* Transitioning time exceeded, set port to standby */
 582                 err = SCSI_DH_RETRY;
 583                 h->state = TPGS_STATE_STANDBY;
 584                 break;
 585         case TPGS_STATE_OFFLINE:
 586         case TPGS_STATE_UNAVAILABLE:
 587                 /* Path unusable for unavailable/offline */
 588                 err = SCSI_DH_DEV_OFFLINED;
 589                 break;
 590         default:
 591                 /* Useable path if active */
 592                 err = SCSI_DH_OK;
 593                 break;
 594         }
 595         return err;
 596 }
 597
 598 /*
 599  * alua_initialize - Initialize ALUA state
 600  * @sdev: the device to be initialized
 601  *
 602  * For the prep_fn to work correctly we have
 603  * to initialize the ALUA state for the device.
 604  */
 605 static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h)
 606 {
 607         int err;
 608
 609         err = alua_check_tpgs(sdev, h);
 610         if (err != SCSI_DH_OK)
 611                 goto out;
 612
 613         err = alua_vpd_inquiry(sdev, h);
 614         if (err != SCSI_DH_OK)
 615                 goto out;
 616
 617         err = alua_rtpg(sdev, h);
 618         if (err != SCSI_DH_OK)
 619                 goto out;
 620
 621 out:
 622         return err;
 623 }
 624
 625 /*
 626  * alua_activate - activate a path
 627  * @sdev: device on the path to be activated
 628  *
 629  * We're currently switching the port group to be activated only and
 630  * let the array figure out the rest.
 631  * There may be other arrays which require us to switch all port groups
 632  * based on a certain policy. But until we actually encounter them it
 633  * should be okay.
 634  */
 635 static int alua_activate(struct scsi_device *sdev,
 636                         activate_complete fn, void *data)
 637 {
 638         struct alua_dh_data *h = get_alua_data(sdev);
 639         int err = SCSI_DH_OK;
 640
 641         err = alua_rtpg(sdev, h);
 642         if (err != SCSI_DH_OK)
 643                 goto out;
 644
 645         if (h->tpgs & TPGS_MODE_EXPLICIT &&
 646             h->state != TPGS_STATE_OPTIMIZED &&
 647             h->state != TPGS_STATE_LBA_DEPENDENT) {
 648                 h->callback_fn = fn;
 649                 h->callback_data = data;
 650                 err = submit_stpg(h);
 651                 if (err == SCSI_DH_OK)
 652                         return 0;
 653                 h->callback_fn = h->callback_data = NULL;
 654         }
 655
 656 out:
 657         if (fn)
 658                 fn(data, err);
 659         return 0;
 660 }
 661
 662 /*
 663  * alua_prep_fn - request callback
 664  *
 665  * Fail I/O to all paths not in state
 666  * active/optimized or active/non-optimized.
 667  */
 668 static int alua_prep_fn(struct scsi_device *sdev, struct request *req)
 669 {
 670         struct alua_dh_data *h = get_alua_data(sdev);
 671         int ret = BLKPREP_OK;
 672
 673         if (h->state == TPGS_STATE_TRANSITIONING)
 674                 ret = BLKPREP_DEFER;
 675         else if (h->state != TPGS_STATE_OPTIMIZED &&
 676                  h->state != TPGS_STATE_NONOPTIMIZED &&
 677                  h->state != TPGS_STATE_LBA_DEPENDENT) {
 678                 ret = BLKPREP_KILL;
 679                 req->cmd_flags |= REQ_QUIET;
 680         }
 681         return ret;
 682
 683 }
 684
 685 static bool alua_match(struct scsi_device *sdev)
 686 {
 687         return (scsi_device_tpgs(sdev) != 0);
 688 }
 689
 690 static int alua_bus_attach(struct scsi_device *sdev);
 691 static void alua_bus_detach(struct scsi_device *sdev);
 692
 693 static struct scsi_device_handler alua_dh = {
 694         .name = ALUA_DH_NAME,
 695         .module = THIS_MODULE,
 696         .attach = alua_bus_attach,
 697         .detach = alua_bus_detach,
 698         .prep_fn = alua_prep_fn,
 699         .check_sense = alua_check_sense,
 700         .activate = alua_activate,
 701         .match = alua_match,
 702 };
 703
 704 /*
 705  * alua_bus_attach - Attach device handler
 706  * @sdev: device to be attached to
 707  */
 708 static int alua_bus_attach(struct scsi_device *sdev)
 709 {
 710         struct scsi_dh_data *scsi_dh_data;
 711         struct alua_dh_data *h;
 712         unsigned long flags;
 713         int err = SCSI_DH_OK;
 714
 715         scsi_dh_data = kzalloc(sizeof(*scsi_dh_data)
 716                                + sizeof(*h) , GFP_KERNEL);
 717         if (!scsi_dh_data) {
 718                 sdev_printk(KERN_ERR, sdev, "%s: Attach failed\n",
 719                             ALUA_DH_NAME);
 720                 return -ENOMEM;
 721         }
 722
 723         scsi_dh_data->scsi_dh = &alua_dh;
 724         h = (struct alua_dh_data *) scsi_dh_data->buf;
 725         h->tpgs = TPGS_MODE_UNINITIALIZED;
 726         h->state = TPGS_STATE_OPTIMIZED;
 727         h->group_id = -1;
 728         h->rel_port = -1;
 729         h->buff = h->inq;
 730         h->bufflen = ALUA_INQUIRY_SIZE;
 731         h->sdev = sdev;
 732
 733         err = alua_initialize(sdev, h);
 734         if ((err != SCSI_DH_OK) && (err != SCSI_DH_DEV_OFFLINED))
 735                 goto failed;
 736
 737         if (!try_module_get(THIS_MODULE))
 738                 goto failed;
 739
 740         spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
 741         sdev->scsi_dh_data = scsi_dh_data;
 742         spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
 743         sdev_printk(KERN_NOTICE, sdev, "%s: Attached\n", ALUA_DH_NAME);
 744
 745         return 0;
 746
 747 failed:
 748         kfree(scsi_dh_data);
 749         sdev_printk(KERN_ERR, sdev, "%s: not attached\n", ALUA_DH_NAME);
 750         return -EINVAL;
 751 }
 752
 753 /*
 754  * alua_bus_detach - Detach device handler
 755  * @sdev: device to be detached from
 756  */
 757 static void alua_bus_detach(struct scsi_device *sdev)
 758 {
 759         struct scsi_dh_data *scsi_dh_data;
 760         struct alua_dh_data *h;
 761         unsigned long flags;
 762
 763         spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
 764         scsi_dh_data = sdev->scsi_dh_data;
 765         sdev->scsi_dh_data = NULL;
 766         spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
 767
 768         h = (struct alua_dh_data *) scsi_dh_data->buf;
 769         if (h->buff && h->inq != h->buff)
 770                 kfree(h->buff);
 771         kfree(scsi_dh_data);
 772         module_put(THIS_MODULE);
 773         sdev_printk(KERN_NOTICE, sdev, "%s: Detached\n", ALUA_DH_NAME);
 774 }
 775
 776 static int __init alua_init(void)
 777 {
 778         int r;
 779
 780         r = scsi_register_device_handler(&alua_dh);
 781         if (r != 0)
 782                 printk(KERN_ERR "%s: Failed to register scsi device handler",
 783                         ALUA_DH_NAME);
 784         return r;
 785 }
 786
 787 static void __exit alua_exit(void)
 788 {
 789         scsi_unregister_device_handler(&alua_dh);
 790 }
 791
 792 module_init(alua_init);
 793 module_exit(alua_exit);
 794
 795 MODULE_DESCRIPTION("DM Multipath ALUA support");
 796 MODULE_AUTHOR("Hannes Reinecke <hare@suse.de>");
 797 MODULE_LICENSE("GPL");
 798 MODULE_VERSION(ALUA_DH_VER);