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