1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Generic SCSI-3 ALUA SCSI Device Handler 4 * 5 * Copyright (C) 2007-2010 Hannes Reinecke, SUSE Linux Products GmbH. 6 * All rights reserved. 7 */ 8 #include <linux/slab.h> 9 #include <linux/delay.h> 10 #include <linux/module.h> 11 #include <asm/unaligned.h> 12 #include <scsi/scsi.h> 13 #include <scsi/scsi_proto.h> 14 #include <scsi/scsi_dbg.h> 15 #include <scsi/scsi_eh.h> 16 #include <scsi/scsi_dh.h> 17 18 #define ALUA_DH_NAME "alua" 19 #define ALUA_DH_VER "2.0" 20 21 #define TPGS_SUPPORT_NONE 0x00 22 #define TPGS_SUPPORT_OPTIMIZED 0x01 23 #define TPGS_SUPPORT_NONOPTIMIZED 0x02 24 #define TPGS_SUPPORT_STANDBY 0x04 25 #define TPGS_SUPPORT_UNAVAILABLE 0x08 26 #define TPGS_SUPPORT_LBA_DEPENDENT 0x10 27 #define TPGS_SUPPORT_OFFLINE 0x40 28 #define TPGS_SUPPORT_TRANSITION 0x80 29 #define TPGS_SUPPORT_ALL 0xdf 30 31 #define RTPG_FMT_MASK 0x70 32 #define RTPG_FMT_EXT_HDR 0x10 33 34 #define TPGS_MODE_UNINITIALIZED -1 35 #define TPGS_MODE_NONE 0x0 36 #define TPGS_MODE_IMPLICIT 0x1 37 #define TPGS_MODE_EXPLICIT 0x2 38 39 #define ALUA_RTPG_SIZE 128 40 #define ALUA_FAILOVER_TIMEOUT 60 41 #define ALUA_FAILOVER_RETRIES 5 42 #define ALUA_RTPG_DELAY_MSECS 5 43 #define ALUA_RTPG_RETRY_DELAY 2 44 45 /* device handler flags */ 46 #define ALUA_OPTIMIZE_STPG 0x01 47 #define ALUA_RTPG_EXT_HDR_UNSUPP 0x02 48 /* State machine flags */ 49 #define ALUA_PG_RUN_RTPG 0x10 50 #define ALUA_PG_RUN_STPG 0x20 51 #define ALUA_PG_RUNNING 0x40 52 53 static uint optimize_stpg; 54 module_param(optimize_stpg, uint, S_IRUGO|S_IWUSR); 55 MODULE_PARM_DESC(optimize_stpg, "Allow use of a non-optimized path, rather than sending a STPG, when implicit TPGS is supported (0=No,1=Yes). Default is 0."); 56 57 static LIST_HEAD(port_group_list); 58 static DEFINE_SPINLOCK(port_group_lock); 59 static struct workqueue_struct *kaluad_wq; 60 61 struct alua_port_group { 62 struct kref kref; 63 struct rcu_head rcu; 64 struct list_head node; 65 struct list_head dh_list; 66 unsigned char device_id_str[256]; 67 int device_id_len; 68 int group_id; 69 int tpgs; 70 int state; 71 int pref; 72 int valid_states; 73 unsigned flags; /* used for optimizing STPG */ 74 unsigned char transition_tmo; 75 unsigned long expiry; 76 unsigned long interval; 77 struct delayed_work rtpg_work; 78 spinlock_t lock; 79 struct list_head rtpg_list; 80 struct scsi_device *rtpg_sdev; 81 }; 82 83 struct alua_dh_data { 84 struct list_head node; 85 struct alua_port_group __rcu *pg; 86 int group_id; 87 spinlock_t pg_lock; 88 struct scsi_device *sdev; 89 int init_error; 90 struct mutex init_mutex; 91 bool disabled; 92 }; 93 94 struct alua_queue_data { 95 struct list_head entry; 96 activate_complete callback_fn; 97 void *callback_data; 98 }; 99 100 #define ALUA_POLICY_SWITCH_CURRENT 0 101 #define ALUA_POLICY_SWITCH_ALL 1 102 103 static void alua_rtpg_work(struct work_struct *work); 104 static bool alua_rtpg_queue(struct alua_port_group *pg, 105 struct scsi_device *sdev, 106 struct alua_queue_data *qdata, bool force); 107 static void alua_check(struct scsi_device *sdev, bool force); 108 109 static void release_port_group(struct kref *kref) 110 { 111 struct alua_port_group *pg; 112 113 pg = container_of(kref, struct alua_port_group, kref); 114 if (pg->rtpg_sdev) 115 flush_delayed_work(&pg->rtpg_work); 116 spin_lock(&port_group_lock); 117 list_del(&pg->node); 118 spin_unlock(&port_group_lock); 119 kfree_rcu(pg, rcu); 120 } 121 122 /* 123 * submit_rtpg - Issue a REPORT TARGET GROUP STATES command 124 * @sdev: sdev the command should be sent to 125 */ 126 static int submit_rtpg(struct scsi_device *sdev, unsigned char *buff, 127 int bufflen, struct scsi_sense_hdr *sshdr, int flags) 128 { 129 u8 cdb[MAX_COMMAND_SIZE]; 130 int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | 131 REQ_FAILFAST_DRIVER; 132 133 /* Prepare the command. */ 134 memset(cdb, 0x0, MAX_COMMAND_SIZE); 135 cdb[0] = MAINTENANCE_IN; 136 if (!(flags & ALUA_RTPG_EXT_HDR_UNSUPP)) 137 cdb[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT; 138 else 139 cdb[1] = MI_REPORT_TARGET_PGS; 140 put_unaligned_be32(bufflen, &cdb[6]); 141 142 return scsi_execute(sdev, cdb, DMA_FROM_DEVICE, buff, bufflen, NULL, 143 sshdr, ALUA_FAILOVER_TIMEOUT * HZ, 144 ALUA_FAILOVER_RETRIES, req_flags, 0, NULL); 145 } 146 147 /* 148 * submit_stpg - Issue a SET TARGET PORT GROUP command 149 * 150 * Currently we're only setting the current target port group state 151 * to 'active/optimized' and let the array firmware figure out 152 * the states of the remaining groups. 153 */ 154 static int submit_stpg(struct scsi_device *sdev, int group_id, 155 struct scsi_sense_hdr *sshdr) 156 { 157 u8 cdb[MAX_COMMAND_SIZE]; 158 unsigned char stpg_data[8]; 159 int stpg_len = 8; 160 int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | 161 REQ_FAILFAST_DRIVER; 162 163 /* Prepare the data buffer */ 164 memset(stpg_data, 0, stpg_len); 165 stpg_data[4] = SCSI_ACCESS_STATE_OPTIMAL; 166 put_unaligned_be16(group_id, &stpg_data[6]); 167 168 /* Prepare the command. */ 169 memset(cdb, 0x0, MAX_COMMAND_SIZE); 170 cdb[0] = MAINTENANCE_OUT; 171 cdb[1] = MO_SET_TARGET_PGS; 172 put_unaligned_be32(stpg_len, &cdb[6]); 173 174 return scsi_execute(sdev, cdb, DMA_TO_DEVICE, stpg_data, stpg_len, NULL, 175 sshdr, ALUA_FAILOVER_TIMEOUT * HZ, 176 ALUA_FAILOVER_RETRIES, req_flags, 0, NULL); 177 } 178 179 static struct alua_port_group *alua_find_get_pg(char *id_str, size_t id_size, 180 int group_id) 181 { 182 struct alua_port_group *pg; 183 184 if (!id_str || !id_size || !strlen(id_str)) 185 return NULL; 186 187 list_for_each_entry(pg, &port_group_list, node) { 188 if (pg->group_id != group_id) 189 continue; 190 if (!pg->device_id_len || pg->device_id_len != id_size) 191 continue; 192 if (strncmp(pg->device_id_str, id_str, id_size)) 193 continue; 194 if (!kref_get_unless_zero(&pg->kref)) 195 continue; 196 return pg; 197 } 198 199 return NULL; 200 } 201 202 /* 203 * alua_alloc_pg - Allocate a new port_group structure 204 * @sdev: scsi device 205 * @group_id: port group id 206 * @tpgs: target port group settings 207 * 208 * Allocate a new port_group structure for a given 209 * device. 210 */ 211 static struct alua_port_group *alua_alloc_pg(struct scsi_device *sdev, 212 int group_id, int tpgs) 213 { 214 struct alua_port_group *pg, *tmp_pg; 215 216 pg = kzalloc(sizeof(struct alua_port_group), GFP_KERNEL); 217 if (!pg) 218 return ERR_PTR(-ENOMEM); 219 220 pg->device_id_len = scsi_vpd_lun_id(sdev, pg->device_id_str, 221 sizeof(pg->device_id_str)); 222 if (pg->device_id_len <= 0) { 223 /* 224 * TPGS supported but no device identification found. 225 * Generate private device identification. 226 */ 227 sdev_printk(KERN_INFO, sdev, 228 "%s: No device descriptors found\n", 229 ALUA_DH_NAME); 230 pg->device_id_str[0] = '\0'; 231 pg->device_id_len = 0; 232 } 233 pg->group_id = group_id; 234 pg->tpgs = tpgs; 235 pg->state = SCSI_ACCESS_STATE_OPTIMAL; 236 pg->valid_states = TPGS_SUPPORT_ALL; 237 if (optimize_stpg) 238 pg->flags |= ALUA_OPTIMIZE_STPG; 239 kref_init(&pg->kref); 240 INIT_DELAYED_WORK(&pg->rtpg_work, alua_rtpg_work); 241 INIT_LIST_HEAD(&pg->rtpg_list); 242 INIT_LIST_HEAD(&pg->node); 243 INIT_LIST_HEAD(&pg->dh_list); 244 spin_lock_init(&pg->lock); 245 246 spin_lock(&port_group_lock); 247 tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len, 248 group_id); 249 if (tmp_pg) { 250 spin_unlock(&port_group_lock); 251 kfree(pg); 252 return tmp_pg; 253 } 254 255 list_add(&pg->node, &port_group_list); 256 spin_unlock(&port_group_lock); 257 258 return pg; 259 } 260 261 /* 262 * alua_check_tpgs - Evaluate TPGS setting 263 * @sdev: device to be checked 264 * 265 * Examine the TPGS setting of the sdev to find out if ALUA 266 * is supported. 267 */ 268 static int alua_check_tpgs(struct scsi_device *sdev) 269 { 270 int tpgs = TPGS_MODE_NONE; 271 272 /* 273 * ALUA support for non-disk devices is fraught with 274 * difficulties, so disable it for now. 275 */ 276 if (sdev->type != TYPE_DISK) { 277 sdev_printk(KERN_INFO, sdev, 278 "%s: disable for non-disk devices\n", 279 ALUA_DH_NAME); 280 return tpgs; 281 } 282 283 tpgs = scsi_device_tpgs(sdev); 284 switch (tpgs) { 285 case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT: 286 sdev_printk(KERN_INFO, sdev, 287 "%s: supports implicit and explicit TPGS\n", 288 ALUA_DH_NAME); 289 break; 290 case TPGS_MODE_EXPLICIT: 291 sdev_printk(KERN_INFO, sdev, "%s: supports explicit TPGS\n", 292 ALUA_DH_NAME); 293 break; 294 case TPGS_MODE_IMPLICIT: 295 sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n", 296 ALUA_DH_NAME); 297 break; 298 case TPGS_MODE_NONE: 299 sdev_printk(KERN_INFO, sdev, "%s: not supported\n", 300 ALUA_DH_NAME); 301 break; 302 default: 303 sdev_printk(KERN_INFO, sdev, 304 "%s: unsupported TPGS setting %d\n", 305 ALUA_DH_NAME, tpgs); 306 tpgs = TPGS_MODE_NONE; 307 break; 308 } 309 310 return tpgs; 311 } 312 313 /* 314 * alua_check_vpd - Evaluate INQUIRY vpd page 0x83 315 * @sdev: device to be checked 316 * 317 * Extract the relative target port and the target port group 318 * descriptor from the list of identificators. 319 */ 320 static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h, 321 int tpgs) 322 { 323 int rel_port = -1, group_id; 324 struct alua_port_group *pg, *old_pg = NULL; 325 bool pg_updated = false; 326 unsigned long flags; 327 328 group_id = scsi_vpd_tpg_id(sdev, &rel_port); 329 if (group_id < 0) { 330 /* 331 * Internal error; TPGS supported but required 332 * VPD identification descriptors not present. 333 * Disable ALUA support 334 */ 335 sdev_printk(KERN_INFO, sdev, 336 "%s: No target port descriptors found\n", 337 ALUA_DH_NAME); 338 return SCSI_DH_DEV_UNSUPP; 339 } 340 341 pg = alua_alloc_pg(sdev, group_id, tpgs); 342 if (IS_ERR(pg)) { 343 if (PTR_ERR(pg) == -ENOMEM) 344 return SCSI_DH_NOMEM; 345 return SCSI_DH_DEV_UNSUPP; 346 } 347 if (pg->device_id_len) 348 sdev_printk(KERN_INFO, sdev, 349 "%s: device %s port group %x rel port %x\n", 350 ALUA_DH_NAME, pg->device_id_str, 351 group_id, rel_port); 352 else 353 sdev_printk(KERN_INFO, sdev, 354 "%s: port group %x rel port %x\n", 355 ALUA_DH_NAME, group_id, rel_port); 356 357 /* Check for existing port group references */ 358 spin_lock(&h->pg_lock); 359 old_pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock)); 360 if (old_pg != pg) { 361 /* port group has changed. Update to new port group */ 362 if (h->pg) { 363 spin_lock_irqsave(&old_pg->lock, flags); 364 list_del_rcu(&h->node); 365 spin_unlock_irqrestore(&old_pg->lock, flags); 366 } 367 rcu_assign_pointer(h->pg, pg); 368 pg_updated = true; 369 } 370 371 spin_lock_irqsave(&pg->lock, flags); 372 if (pg_updated) 373 list_add_rcu(&h->node, &pg->dh_list); 374 spin_unlock_irqrestore(&pg->lock, flags); 375 376 alua_rtpg_queue(rcu_dereference_protected(h->pg, 377 lockdep_is_held(&h->pg_lock)), 378 sdev, NULL, true); 379 spin_unlock(&h->pg_lock); 380 381 if (old_pg) 382 kref_put(&old_pg->kref, release_port_group); 383 384 return SCSI_DH_OK; 385 } 386 387 static char print_alua_state(unsigned char state) 388 { 389 switch (state) { 390 case SCSI_ACCESS_STATE_OPTIMAL: 391 return 'A'; 392 case SCSI_ACCESS_STATE_ACTIVE: 393 return 'N'; 394 case SCSI_ACCESS_STATE_STANDBY: 395 return 'S'; 396 case SCSI_ACCESS_STATE_UNAVAILABLE: 397 return 'U'; 398 case SCSI_ACCESS_STATE_LBA: 399 return 'L'; 400 case SCSI_ACCESS_STATE_OFFLINE: 401 return 'O'; 402 case SCSI_ACCESS_STATE_TRANSITIONING: 403 return 'T'; 404 default: 405 return 'X'; 406 } 407 } 408 409 static enum scsi_disposition alua_check_sense(struct scsi_device *sdev, 410 struct scsi_sense_hdr *sense_hdr) 411 { 412 struct alua_dh_data *h = sdev->handler_data; 413 struct alua_port_group *pg; 414 415 switch (sense_hdr->sense_key) { 416 case NOT_READY: 417 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) { 418 /* 419 * LUN Not Accessible - ALUA state transition 420 */ 421 rcu_read_lock(); 422 pg = rcu_dereference(h->pg); 423 if (pg) 424 pg->state = SCSI_ACCESS_STATE_TRANSITIONING; 425 rcu_read_unlock(); 426 alua_check(sdev, false); 427 return NEEDS_RETRY; 428 } 429 break; 430 case UNIT_ATTENTION: 431 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) { 432 /* 433 * Power On, Reset, or Bus Device Reset. 434 * Might have obscured a state transition, 435 * so schedule a recheck. 436 */ 437 alua_check(sdev, true); 438 return ADD_TO_MLQUEUE; 439 } 440 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04) 441 /* 442 * Device internal reset 443 */ 444 return ADD_TO_MLQUEUE; 445 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01) 446 /* 447 * Mode Parameters Changed 448 */ 449 return ADD_TO_MLQUEUE; 450 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06) { 451 /* 452 * ALUA state changed 453 */ 454 alua_check(sdev, true); 455 return ADD_TO_MLQUEUE; 456 } 457 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07) { 458 /* 459 * Implicit ALUA state transition failed 460 */ 461 alua_check(sdev, true); 462 return ADD_TO_MLQUEUE; 463 } 464 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03) 465 /* 466 * Inquiry data has changed 467 */ 468 return ADD_TO_MLQUEUE; 469 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x0e) 470 /* 471 * REPORTED_LUNS_DATA_HAS_CHANGED is reported 472 * when switching controllers on targets like 473 * Intel Multi-Flex. We can just retry. 474 */ 475 return ADD_TO_MLQUEUE; 476 break; 477 } 478 479 return SCSI_RETURN_NOT_HANDLED; 480 } 481 482 /* 483 * alua_tur - Send a TEST UNIT READY 484 * @sdev: device to which the TEST UNIT READY command should be send 485 * 486 * Send a TEST UNIT READY to @sdev to figure out the device state 487 * Returns SCSI_DH_RETRY if the sense code is NOT READY/ALUA TRANSITIONING, 488 * SCSI_DH_OK if no error occurred, and SCSI_DH_IO otherwise. 489 */ 490 static int alua_tur(struct scsi_device *sdev) 491 { 492 struct scsi_sense_hdr sense_hdr; 493 int retval; 494 495 retval = scsi_test_unit_ready(sdev, ALUA_FAILOVER_TIMEOUT * HZ, 496 ALUA_FAILOVER_RETRIES, &sense_hdr); 497 if (sense_hdr.sense_key == NOT_READY && 498 sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) 499 return SCSI_DH_RETRY; 500 else if (retval) 501 return SCSI_DH_IO; 502 else 503 return SCSI_DH_OK; 504 } 505 506 /* 507 * alua_rtpg - Evaluate REPORT TARGET GROUP STATES 508 * @sdev: the device to be evaluated. 509 * 510 * Evaluate the Target Port Group State. 511 * Returns SCSI_DH_DEV_OFFLINED if the path is 512 * found to be unusable. 513 */ 514 static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg) 515 { 516 struct scsi_sense_hdr sense_hdr; 517 struct alua_port_group *tmp_pg; 518 int len, k, off, bufflen = ALUA_RTPG_SIZE; 519 int group_id_old, state_old, pref_old, valid_states_old; 520 unsigned char *desc, *buff; 521 unsigned err; 522 int retval; 523 unsigned int tpg_desc_tbl_off; 524 unsigned char orig_transition_tmo; 525 unsigned long flags; 526 bool transitioning_sense = false; 527 528 group_id_old = pg->group_id; 529 state_old = pg->state; 530 pref_old = pg->pref; 531 valid_states_old = pg->valid_states; 532 533 if (!pg->expiry) { 534 unsigned long transition_tmo = ALUA_FAILOVER_TIMEOUT * HZ; 535 536 if (pg->transition_tmo) 537 transition_tmo = pg->transition_tmo * HZ; 538 539 pg->expiry = round_jiffies_up(jiffies + transition_tmo); 540 } 541 542 buff = kzalloc(bufflen, GFP_KERNEL); 543 if (!buff) 544 return SCSI_DH_DEV_TEMP_BUSY; 545 546 retry: 547 err = 0; 548 retval = submit_rtpg(sdev, buff, bufflen, &sense_hdr, pg->flags); 549 550 if (retval) { 551 /* 552 * Some (broken) implementations have a habit of returning 553 * an error during things like firmware update etc. 554 * But if the target only supports active/optimized there's 555 * not much we can do; it's not that we can switch paths 556 * or anything. 557 * So ignore any errors to avoid spurious failures during 558 * path failover. 559 */ 560 if ((pg->valid_states & ~TPGS_SUPPORT_OPTIMIZED) == 0) { 561 sdev_printk(KERN_INFO, sdev, 562 "%s: ignoring rtpg result %d\n", 563 ALUA_DH_NAME, retval); 564 kfree(buff); 565 return SCSI_DH_OK; 566 } 567 if (retval < 0 || !scsi_sense_valid(&sense_hdr)) { 568 sdev_printk(KERN_INFO, sdev, 569 "%s: rtpg failed, result %d\n", 570 ALUA_DH_NAME, retval); 571 kfree(buff); 572 if (retval < 0) 573 return SCSI_DH_DEV_TEMP_BUSY; 574 if (host_byte(retval) == DID_NO_CONNECT) 575 return SCSI_DH_RES_TEMP_UNAVAIL; 576 return SCSI_DH_IO; 577 } 578 579 /* 580 * submit_rtpg() has failed on existing arrays 581 * when requesting extended header info, and 582 * the array doesn't support extended headers, 583 * even though it shouldn't according to T10. 584 * The retry without rtpg_ext_hdr_req set 585 * handles this. 586 * Note: some arrays return a sense key of ILLEGAL_REQUEST 587 * with ASC 00h if they don't support the extended header. 588 */ 589 if (!(pg->flags & ALUA_RTPG_EXT_HDR_UNSUPP) && 590 sense_hdr.sense_key == ILLEGAL_REQUEST) { 591 pg->flags |= ALUA_RTPG_EXT_HDR_UNSUPP; 592 goto retry; 593 } 594 /* 595 * If the array returns with 'ALUA state transition' 596 * sense code here it cannot return RTPG data during 597 * transition. So set the state to 'transitioning' directly. 598 */ 599 if (sense_hdr.sense_key == NOT_READY && 600 sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) { 601 transitioning_sense = true; 602 goto skip_rtpg; 603 } 604 /* 605 * Retry on any other UNIT ATTENTION occurred. 606 */ 607 if (sense_hdr.sense_key == UNIT_ATTENTION) 608 err = SCSI_DH_RETRY; 609 if (err == SCSI_DH_RETRY && 610 pg->expiry != 0 && time_before(jiffies, pg->expiry)) { 611 sdev_printk(KERN_ERR, sdev, "%s: rtpg retry\n", 612 ALUA_DH_NAME); 613 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr); 614 kfree(buff); 615 return err; 616 } 617 sdev_printk(KERN_ERR, sdev, "%s: rtpg failed\n", 618 ALUA_DH_NAME); 619 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr); 620 kfree(buff); 621 pg->expiry = 0; 622 return SCSI_DH_IO; 623 } 624 625 len = get_unaligned_be32(&buff[0]) + 4; 626 627 if (len > bufflen) { 628 /* Resubmit with the correct length */ 629 kfree(buff); 630 bufflen = len; 631 buff = kmalloc(bufflen, GFP_KERNEL); 632 if (!buff) { 633 sdev_printk(KERN_WARNING, sdev, 634 "%s: kmalloc buffer failed\n",__func__); 635 /* Temporary failure, bypass */ 636 pg->expiry = 0; 637 return SCSI_DH_DEV_TEMP_BUSY; 638 } 639 goto retry; 640 } 641 642 orig_transition_tmo = pg->transition_tmo; 643 if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR && buff[5] != 0) 644 pg->transition_tmo = buff[5]; 645 else 646 pg->transition_tmo = ALUA_FAILOVER_TIMEOUT; 647 648 if (orig_transition_tmo != pg->transition_tmo) { 649 sdev_printk(KERN_INFO, sdev, 650 "%s: transition timeout set to %d seconds\n", 651 ALUA_DH_NAME, pg->transition_tmo); 652 pg->expiry = jiffies + pg->transition_tmo * HZ; 653 } 654 655 if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR) 656 tpg_desc_tbl_off = 8; 657 else 658 tpg_desc_tbl_off = 4; 659 660 for (k = tpg_desc_tbl_off, desc = buff + tpg_desc_tbl_off; 661 k < len; 662 k += off, desc += off) { 663 u16 group_id = get_unaligned_be16(&desc[2]); 664 665 spin_lock_irqsave(&port_group_lock, flags); 666 tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len, 667 group_id); 668 spin_unlock_irqrestore(&port_group_lock, flags); 669 if (tmp_pg) { 670 if (spin_trylock_irqsave(&tmp_pg->lock, flags)) { 671 if ((tmp_pg == pg) || 672 !(tmp_pg->flags & ALUA_PG_RUNNING)) { 673 struct alua_dh_data *h; 674 675 tmp_pg->state = desc[0] & 0x0f; 676 tmp_pg->pref = desc[0] >> 7; 677 rcu_read_lock(); 678 list_for_each_entry_rcu(h, 679 &tmp_pg->dh_list, node) { 680 if (!h->sdev) 681 continue; 682 h->sdev->access_state = desc[0]; 683 } 684 rcu_read_unlock(); 685 } 686 if (tmp_pg == pg) 687 tmp_pg->valid_states = desc[1]; 688 spin_unlock_irqrestore(&tmp_pg->lock, flags); 689 } 690 kref_put(&tmp_pg->kref, release_port_group); 691 } 692 off = 8 + (desc[7] * 4); 693 } 694 695 skip_rtpg: 696 spin_lock_irqsave(&pg->lock, flags); 697 if (transitioning_sense) 698 pg->state = SCSI_ACCESS_STATE_TRANSITIONING; 699 700 if (group_id_old != pg->group_id || state_old != pg->state || 701 pref_old != pg->pref || valid_states_old != pg->valid_states) 702 sdev_printk(KERN_INFO, sdev, 703 "%s: port group %02x state %c %s supports %c%c%c%c%c%c%c\n", 704 ALUA_DH_NAME, pg->group_id, print_alua_state(pg->state), 705 pg->pref ? "preferred" : "non-preferred", 706 pg->valid_states&TPGS_SUPPORT_TRANSITION?'T':'t', 707 pg->valid_states&TPGS_SUPPORT_OFFLINE?'O':'o', 708 pg->valid_states&TPGS_SUPPORT_LBA_DEPENDENT?'L':'l', 709 pg->valid_states&TPGS_SUPPORT_UNAVAILABLE?'U':'u', 710 pg->valid_states&TPGS_SUPPORT_STANDBY?'S':'s', 711 pg->valid_states&TPGS_SUPPORT_NONOPTIMIZED?'N':'n', 712 pg->valid_states&TPGS_SUPPORT_OPTIMIZED?'A':'a'); 713 714 switch (pg->state) { 715 case SCSI_ACCESS_STATE_TRANSITIONING: 716 if (time_before(jiffies, pg->expiry)) { 717 /* State transition, retry */ 718 pg->interval = ALUA_RTPG_RETRY_DELAY; 719 err = SCSI_DH_RETRY; 720 } else { 721 struct alua_dh_data *h; 722 723 /* Transitioning time exceeded, set port to standby */ 724 err = SCSI_DH_IO; 725 pg->state = SCSI_ACCESS_STATE_STANDBY; 726 pg->expiry = 0; 727 rcu_read_lock(); 728 list_for_each_entry_rcu(h, &pg->dh_list, node) { 729 if (!h->sdev) 730 continue; 731 h->sdev->access_state = 732 (pg->state & SCSI_ACCESS_STATE_MASK); 733 if (pg->pref) 734 h->sdev->access_state |= 735 SCSI_ACCESS_STATE_PREFERRED; 736 } 737 rcu_read_unlock(); 738 } 739 break; 740 case SCSI_ACCESS_STATE_OFFLINE: 741 /* Path unusable */ 742 err = SCSI_DH_DEV_OFFLINED; 743 pg->expiry = 0; 744 break; 745 default: 746 /* Useable path if active */ 747 err = SCSI_DH_OK; 748 pg->expiry = 0; 749 break; 750 } 751 spin_unlock_irqrestore(&pg->lock, flags); 752 kfree(buff); 753 return err; 754 } 755 756 /* 757 * alua_stpg - Issue a SET TARGET PORT GROUP command 758 * 759 * Issue a SET TARGET PORT GROUP command and evaluate the 760 * response. Returns SCSI_DH_RETRY per default to trigger 761 * a re-evaluation of the target group state or SCSI_DH_OK 762 * if no further action needs to be taken. 763 */ 764 static unsigned alua_stpg(struct scsi_device *sdev, struct alua_port_group *pg) 765 { 766 int retval; 767 struct scsi_sense_hdr sense_hdr; 768 769 if (!(pg->tpgs & TPGS_MODE_EXPLICIT)) { 770 /* Only implicit ALUA supported, retry */ 771 return SCSI_DH_RETRY; 772 } 773 switch (pg->state) { 774 case SCSI_ACCESS_STATE_OPTIMAL: 775 return SCSI_DH_OK; 776 case SCSI_ACCESS_STATE_ACTIVE: 777 if ((pg->flags & ALUA_OPTIMIZE_STPG) && 778 !pg->pref && 779 (pg->tpgs & TPGS_MODE_IMPLICIT)) 780 return SCSI_DH_OK; 781 break; 782 case SCSI_ACCESS_STATE_STANDBY: 783 case SCSI_ACCESS_STATE_UNAVAILABLE: 784 break; 785 case SCSI_ACCESS_STATE_OFFLINE: 786 return SCSI_DH_IO; 787 case SCSI_ACCESS_STATE_TRANSITIONING: 788 break; 789 default: 790 sdev_printk(KERN_INFO, sdev, 791 "%s: stpg failed, unhandled TPGS state %d", 792 ALUA_DH_NAME, pg->state); 793 return SCSI_DH_NOSYS; 794 } 795 retval = submit_stpg(sdev, pg->group_id, &sense_hdr); 796 797 if (retval) { 798 if (retval < 0 || !scsi_sense_valid(&sense_hdr)) { 799 sdev_printk(KERN_INFO, sdev, 800 "%s: stpg failed, result %d", 801 ALUA_DH_NAME, retval); 802 if (retval < 0) 803 return SCSI_DH_DEV_TEMP_BUSY; 804 } else { 805 sdev_printk(KERN_INFO, sdev, "%s: stpg failed\n", 806 ALUA_DH_NAME); 807 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr); 808 } 809 } 810 /* Retry RTPG */ 811 return SCSI_DH_RETRY; 812 } 813 814 static bool alua_rtpg_select_sdev(struct alua_port_group *pg) 815 { 816 struct alua_dh_data *h; 817 struct scsi_device *sdev = NULL; 818 819 lockdep_assert_held(&pg->lock); 820 if (WARN_ON(!pg->rtpg_sdev)) 821 return false; 822 823 /* 824 * RCU protection isn't necessary for dh_list here 825 * as we hold pg->lock, but for access to h->pg. 826 */ 827 rcu_read_lock(); 828 list_for_each_entry_rcu(h, &pg->dh_list, node) { 829 if (!h->sdev) 830 continue; 831 if (h->sdev == pg->rtpg_sdev) { 832 h->disabled = true; 833 continue; 834 } 835 if (rcu_dereference(h->pg) == pg && 836 !h->disabled && 837 !scsi_device_get(h->sdev)) { 838 sdev = h->sdev; 839 break; 840 } 841 } 842 rcu_read_unlock(); 843 844 if (!sdev) { 845 pr_warn("%s: no device found for rtpg\n", 846 (pg->device_id_len ? 847 (char *)pg->device_id_str : "(nameless PG)")); 848 return false; 849 } 850 851 sdev_printk(KERN_INFO, sdev, "rtpg retry on different device\n"); 852 853 scsi_device_put(pg->rtpg_sdev); 854 pg->rtpg_sdev = sdev; 855 856 return true; 857 } 858 859 static void alua_rtpg_work(struct work_struct *work) 860 { 861 struct alua_port_group *pg = 862 container_of(work, struct alua_port_group, rtpg_work.work); 863 struct scsi_device *sdev; 864 LIST_HEAD(qdata_list); 865 int err = SCSI_DH_OK; 866 struct alua_queue_data *qdata, *tmp; 867 struct alua_dh_data *h; 868 unsigned long flags; 869 870 spin_lock_irqsave(&pg->lock, flags); 871 sdev = pg->rtpg_sdev; 872 if (!sdev) { 873 WARN_ON(pg->flags & ALUA_PG_RUN_RTPG); 874 WARN_ON(pg->flags & ALUA_PG_RUN_STPG); 875 spin_unlock_irqrestore(&pg->lock, flags); 876 kref_put(&pg->kref, release_port_group); 877 return; 878 } 879 pg->flags |= ALUA_PG_RUNNING; 880 if (pg->flags & ALUA_PG_RUN_RTPG) { 881 int state = pg->state; 882 883 pg->flags &= ~ALUA_PG_RUN_RTPG; 884 spin_unlock_irqrestore(&pg->lock, flags); 885 if (state == SCSI_ACCESS_STATE_TRANSITIONING) { 886 if (alua_tur(sdev) == SCSI_DH_RETRY) { 887 spin_lock_irqsave(&pg->lock, flags); 888 pg->flags &= ~ALUA_PG_RUNNING; 889 pg->flags |= ALUA_PG_RUN_RTPG; 890 if (!pg->interval) 891 pg->interval = ALUA_RTPG_RETRY_DELAY; 892 spin_unlock_irqrestore(&pg->lock, flags); 893 queue_delayed_work(kaluad_wq, &pg->rtpg_work, 894 pg->interval * HZ); 895 return; 896 } 897 /* Send RTPG on failure or if TUR indicates SUCCESS */ 898 } 899 err = alua_rtpg(sdev, pg); 900 spin_lock_irqsave(&pg->lock, flags); 901 902 /* If RTPG failed on the current device, try using another */ 903 if (err == SCSI_DH_RES_TEMP_UNAVAIL && 904 alua_rtpg_select_sdev(pg)) 905 err = SCSI_DH_IMM_RETRY; 906 907 if (err == SCSI_DH_RETRY || err == SCSI_DH_IMM_RETRY || 908 pg->flags & ALUA_PG_RUN_RTPG) { 909 pg->flags &= ~ALUA_PG_RUNNING; 910 if (err == SCSI_DH_IMM_RETRY) 911 pg->interval = 0; 912 else if (!pg->interval && !(pg->flags & ALUA_PG_RUN_RTPG)) 913 pg->interval = ALUA_RTPG_RETRY_DELAY; 914 pg->flags |= ALUA_PG_RUN_RTPG; 915 spin_unlock_irqrestore(&pg->lock, flags); 916 queue_delayed_work(kaluad_wq, &pg->rtpg_work, 917 pg->interval * HZ); 918 return; 919 } 920 if (err != SCSI_DH_OK) 921 pg->flags &= ~ALUA_PG_RUN_STPG; 922 } 923 if (pg->flags & ALUA_PG_RUN_STPG) { 924 pg->flags &= ~ALUA_PG_RUN_STPG; 925 spin_unlock_irqrestore(&pg->lock, flags); 926 err = alua_stpg(sdev, pg); 927 spin_lock_irqsave(&pg->lock, flags); 928 if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) { 929 pg->flags |= ALUA_PG_RUN_RTPG; 930 pg->interval = 0; 931 pg->flags &= ~ALUA_PG_RUNNING; 932 spin_unlock_irqrestore(&pg->lock, flags); 933 queue_delayed_work(kaluad_wq, &pg->rtpg_work, 934 pg->interval * HZ); 935 return; 936 } 937 } 938 939 list_splice_init(&pg->rtpg_list, &qdata_list); 940 /* 941 * We went through an RTPG, for good or bad. 942 * Re-enable all devices for the next attempt. 943 */ 944 list_for_each_entry(h, &pg->dh_list, node) 945 h->disabled = false; 946 pg->rtpg_sdev = NULL; 947 spin_unlock_irqrestore(&pg->lock, flags); 948 949 list_for_each_entry_safe(qdata, tmp, &qdata_list, entry) { 950 list_del(&qdata->entry); 951 if (qdata->callback_fn) 952 qdata->callback_fn(qdata->callback_data, err); 953 kfree(qdata); 954 } 955 spin_lock_irqsave(&pg->lock, flags); 956 pg->flags &= ~ALUA_PG_RUNNING; 957 spin_unlock_irqrestore(&pg->lock, flags); 958 scsi_device_put(sdev); 959 kref_put(&pg->kref, release_port_group); 960 } 961 962 /** 963 * alua_rtpg_queue() - cause RTPG to be submitted asynchronously 964 * @pg: ALUA port group associated with @sdev. 965 * @sdev: SCSI device for which to submit an RTPG. 966 * @qdata: Information about the callback to invoke after the RTPG. 967 * @force: Whether or not to submit an RTPG if a work item that will submit an 968 * RTPG already has been scheduled. 969 * 970 * Returns true if and only if alua_rtpg_work() will be called asynchronously. 971 * That function is responsible for calling @qdata->fn(). 972 */ 973 static bool alua_rtpg_queue(struct alua_port_group *pg, 974 struct scsi_device *sdev, 975 struct alua_queue_data *qdata, bool force) 976 { 977 int start_queue = 0; 978 unsigned long flags; 979 if (WARN_ON_ONCE(!pg) || scsi_device_get(sdev)) 980 return false; 981 982 spin_lock_irqsave(&pg->lock, flags); 983 if (qdata) { 984 list_add_tail(&qdata->entry, &pg->rtpg_list); 985 pg->flags |= ALUA_PG_RUN_STPG; 986 force = true; 987 } 988 if (pg->rtpg_sdev == NULL) { 989 pg->interval = 0; 990 pg->flags |= ALUA_PG_RUN_RTPG; 991 kref_get(&pg->kref); 992 pg->rtpg_sdev = sdev; 993 start_queue = 1; 994 } else if (!(pg->flags & ALUA_PG_RUN_RTPG) && force) { 995 pg->flags |= ALUA_PG_RUN_RTPG; 996 /* Do not queue if the worker is already running */ 997 if (!(pg->flags & ALUA_PG_RUNNING)) { 998 kref_get(&pg->kref); 999 start_queue = 1; 1000 } 1001 } 1002 1003 spin_unlock_irqrestore(&pg->lock, flags); 1004 1005 if (start_queue) { 1006 if (queue_delayed_work(kaluad_wq, &pg->rtpg_work, 1007 msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS))) 1008 sdev = NULL; 1009 else 1010 kref_put(&pg->kref, release_port_group); 1011 } 1012 if (sdev) 1013 scsi_device_put(sdev); 1014 1015 return true; 1016 } 1017 1018 /* 1019 * alua_initialize - Initialize ALUA state 1020 * @sdev: the device to be initialized 1021 * 1022 * For the prep_fn to work correctly we have 1023 * to initialize the ALUA state for the device. 1024 */ 1025 static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h) 1026 { 1027 int err = SCSI_DH_DEV_UNSUPP, tpgs; 1028 1029 mutex_lock(&h->init_mutex); 1030 h->disabled = false; 1031 tpgs = alua_check_tpgs(sdev); 1032 if (tpgs != TPGS_MODE_NONE) 1033 err = alua_check_vpd(sdev, h, tpgs); 1034 h->init_error = err; 1035 mutex_unlock(&h->init_mutex); 1036 return err; 1037 } 1038 /* 1039 * alua_set_params - set/unset the optimize flag 1040 * @sdev: device on the path to be activated 1041 * params - parameters in the following format 1042 * "no_of_params\0param1\0param2\0param3\0...\0" 1043 * For example, to set the flag pass the following parameters 1044 * from multipath.conf 1045 * hardware_handler "2 alua 1" 1046 */ 1047 static int alua_set_params(struct scsi_device *sdev, const char *params) 1048 { 1049 struct alua_dh_data *h = sdev->handler_data; 1050 struct alua_port_group *pg = NULL; 1051 unsigned int optimize = 0, argc; 1052 const char *p = params; 1053 int result = SCSI_DH_OK; 1054 unsigned long flags; 1055 1056 if ((sscanf(params, "%u", &argc) != 1) || (argc != 1)) 1057 return -EINVAL; 1058 1059 while (*p++) 1060 ; 1061 if ((sscanf(p, "%u", &optimize) != 1) || (optimize > 1)) 1062 return -EINVAL; 1063 1064 rcu_read_lock(); 1065 pg = rcu_dereference(h->pg); 1066 if (!pg) { 1067 rcu_read_unlock(); 1068 return -ENXIO; 1069 } 1070 spin_lock_irqsave(&pg->lock, flags); 1071 if (optimize) 1072 pg->flags |= ALUA_OPTIMIZE_STPG; 1073 else 1074 pg->flags &= ~ALUA_OPTIMIZE_STPG; 1075 spin_unlock_irqrestore(&pg->lock, flags); 1076 rcu_read_unlock(); 1077 1078 return result; 1079 } 1080 1081 /* 1082 * alua_activate - activate a path 1083 * @sdev: device on the path to be activated 1084 * 1085 * We're currently switching the port group to be activated only and 1086 * let the array figure out the rest. 1087 * There may be other arrays which require us to switch all port groups 1088 * based on a certain policy. But until we actually encounter them it 1089 * should be okay. 1090 */ 1091 static int alua_activate(struct scsi_device *sdev, 1092 activate_complete fn, void *data) 1093 { 1094 struct alua_dh_data *h = sdev->handler_data; 1095 int err = SCSI_DH_OK; 1096 struct alua_queue_data *qdata; 1097 struct alua_port_group *pg; 1098 1099 qdata = kzalloc(sizeof(*qdata), GFP_KERNEL); 1100 if (!qdata) { 1101 err = SCSI_DH_RES_TEMP_UNAVAIL; 1102 goto out; 1103 } 1104 qdata->callback_fn = fn; 1105 qdata->callback_data = data; 1106 1107 mutex_lock(&h->init_mutex); 1108 rcu_read_lock(); 1109 pg = rcu_dereference(h->pg); 1110 if (!pg || !kref_get_unless_zero(&pg->kref)) { 1111 rcu_read_unlock(); 1112 kfree(qdata); 1113 err = h->init_error; 1114 mutex_unlock(&h->init_mutex); 1115 goto out; 1116 } 1117 rcu_read_unlock(); 1118 mutex_unlock(&h->init_mutex); 1119 1120 if (alua_rtpg_queue(pg, sdev, qdata, true)) 1121 fn = NULL; 1122 else 1123 err = SCSI_DH_DEV_OFFLINED; 1124 kref_put(&pg->kref, release_port_group); 1125 out: 1126 if (fn) 1127 fn(data, err); 1128 return 0; 1129 } 1130 1131 /* 1132 * alua_check - check path status 1133 * @sdev: device on the path to be checked 1134 * 1135 * Check the device status 1136 */ 1137 static void alua_check(struct scsi_device *sdev, bool force) 1138 { 1139 struct alua_dh_data *h = sdev->handler_data; 1140 struct alua_port_group *pg; 1141 1142 rcu_read_lock(); 1143 pg = rcu_dereference(h->pg); 1144 if (!pg || !kref_get_unless_zero(&pg->kref)) { 1145 rcu_read_unlock(); 1146 return; 1147 } 1148 rcu_read_unlock(); 1149 alua_rtpg_queue(pg, sdev, NULL, force); 1150 kref_put(&pg->kref, release_port_group); 1151 } 1152 1153 /* 1154 * alua_prep_fn - request callback 1155 * 1156 * Fail I/O to all paths not in state 1157 * active/optimized or active/non-optimized. 1158 */ 1159 static blk_status_t alua_prep_fn(struct scsi_device *sdev, struct request *req) 1160 { 1161 struct alua_dh_data *h = sdev->handler_data; 1162 struct alua_port_group *pg; 1163 unsigned char state = SCSI_ACCESS_STATE_OPTIMAL; 1164 1165 rcu_read_lock(); 1166 pg = rcu_dereference(h->pg); 1167 if (pg) 1168 state = pg->state; 1169 rcu_read_unlock(); 1170 1171 switch (state) { 1172 case SCSI_ACCESS_STATE_OPTIMAL: 1173 case SCSI_ACCESS_STATE_ACTIVE: 1174 case SCSI_ACCESS_STATE_LBA: 1175 case SCSI_ACCESS_STATE_TRANSITIONING: 1176 return BLK_STS_OK; 1177 default: 1178 req->rq_flags |= RQF_QUIET; 1179 return BLK_STS_IOERR; 1180 } 1181 } 1182 1183 static void alua_rescan(struct scsi_device *sdev) 1184 { 1185 struct alua_dh_data *h = sdev->handler_data; 1186 1187 alua_initialize(sdev, h); 1188 } 1189 1190 /* 1191 * alua_bus_attach - Attach device handler 1192 * @sdev: device to be attached to 1193 */ 1194 static int alua_bus_attach(struct scsi_device *sdev) 1195 { 1196 struct alua_dh_data *h; 1197 int err; 1198 1199 h = kzalloc(sizeof(*h) , GFP_KERNEL); 1200 if (!h) 1201 return SCSI_DH_NOMEM; 1202 spin_lock_init(&h->pg_lock); 1203 rcu_assign_pointer(h->pg, NULL); 1204 h->init_error = SCSI_DH_OK; 1205 h->sdev = sdev; 1206 INIT_LIST_HEAD(&h->node); 1207 1208 mutex_init(&h->init_mutex); 1209 err = alua_initialize(sdev, h); 1210 if (err != SCSI_DH_OK && err != SCSI_DH_DEV_OFFLINED) 1211 goto failed; 1212 1213 sdev->handler_data = h; 1214 return SCSI_DH_OK; 1215 failed: 1216 kfree(h); 1217 return err; 1218 } 1219 1220 /* 1221 * alua_bus_detach - Detach device handler 1222 * @sdev: device to be detached from 1223 */ 1224 static void alua_bus_detach(struct scsi_device *sdev) 1225 { 1226 struct alua_dh_data *h = sdev->handler_data; 1227 struct alua_port_group *pg; 1228 1229 spin_lock(&h->pg_lock); 1230 pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock)); 1231 rcu_assign_pointer(h->pg, NULL); 1232 spin_unlock(&h->pg_lock); 1233 if (pg) { 1234 spin_lock_irq(&pg->lock); 1235 list_del_rcu(&h->node); 1236 spin_unlock_irq(&pg->lock); 1237 kref_put(&pg->kref, release_port_group); 1238 } 1239 sdev->handler_data = NULL; 1240 synchronize_rcu(); 1241 kfree(h); 1242 } 1243 1244 static struct scsi_device_handler alua_dh = { 1245 .name = ALUA_DH_NAME, 1246 .module = THIS_MODULE, 1247 .attach = alua_bus_attach, 1248 .detach = alua_bus_detach, 1249 .prep_fn = alua_prep_fn, 1250 .check_sense = alua_check_sense, 1251 .activate = alua_activate, 1252 .rescan = alua_rescan, 1253 .set_params = alua_set_params, 1254 }; 1255 1256 static int __init alua_init(void) 1257 { 1258 int r; 1259 1260 kaluad_wq = alloc_workqueue("kaluad", WQ_MEM_RECLAIM, 0); 1261 if (!kaluad_wq) 1262 return -ENOMEM; 1263 1264 r = scsi_register_device_handler(&alua_dh); 1265 if (r != 0) { 1266 printk(KERN_ERR "%s: Failed to register scsi device handler", 1267 ALUA_DH_NAME); 1268 destroy_workqueue(kaluad_wq); 1269 } 1270 return r; 1271 } 1272 1273 static void __exit alua_exit(void) 1274 { 1275 scsi_unregister_device_handler(&alua_dh); 1276 destroy_workqueue(kaluad_wq); 1277 } 1278 1279 module_init(alua_init); 1280 module_exit(alua_exit); 1281 1282 MODULE_DESCRIPTION("DM Multipath ALUA support"); 1283 MODULE_AUTHOR("Hannes Reinecke <hare@suse.de>"); 1284 MODULE_LICENSE("GPL"); 1285 MODULE_VERSION(ALUA_DH_VER); 1286