scsi_lib.c revision d626e3bf728c47746f2129aa00c775d4e8c2a73b
1/* 2 * scsi_lib.c Copyright (C) 1999 Eric Youngdale 3 * 4 * SCSI queueing library. 5 * Initial versions: Eric Youngdale (eric@andante.org). 6 * Based upon conversations with large numbers 7 * of people at Linux Expo. 8 */ 9 10#include <linux/bio.h> 11#include <linux/bitops.h> 12#include <linux/blkdev.h> 13#include <linux/completion.h> 14#include <linux/kernel.h> 15#include <linux/mempool.h> 16#include <linux/slab.h> 17#include <linux/init.h> 18#include <linux/pci.h> 19#include <linux/delay.h> 20#include <linux/hardirq.h> 21#include <linux/scatterlist.h> 22 23#include <scsi/scsi.h> 24#include <scsi/scsi_cmnd.h> 25#include <scsi/scsi_dbg.h> 26#include <scsi/scsi_device.h> 27#include <scsi/scsi_driver.h> 28#include <scsi/scsi_eh.h> 29#include <scsi/scsi_host.h> 30 31#include "scsi_priv.h" 32#include "scsi_logging.h" 33 34 35#define SG_MEMPOOL_NR ARRAY_SIZE(scsi_sg_pools) 36#define SG_MEMPOOL_SIZE 2 37 38struct scsi_host_sg_pool { 39 size_t size; 40 char *name; 41 struct kmem_cache *slab; 42 mempool_t *pool; 43}; 44 45#define SP(x) { x, "sgpool-" __stringify(x) } 46#if (SCSI_MAX_SG_SEGMENTS < 32) 47#error SCSI_MAX_SG_SEGMENTS is too small (must be 32 or greater) 48#endif 49static struct scsi_host_sg_pool scsi_sg_pools[] = { 50 SP(8), 51 SP(16), 52#if (SCSI_MAX_SG_SEGMENTS > 32) 53 SP(32), 54#if (SCSI_MAX_SG_SEGMENTS > 64) 55 SP(64), 56#if (SCSI_MAX_SG_SEGMENTS > 128) 57 SP(128), 58#if (SCSI_MAX_SG_SEGMENTS > 256) 59#error SCSI_MAX_SG_SEGMENTS is too large (256 MAX) 60#endif 61#endif 62#endif 63#endif 64 SP(SCSI_MAX_SG_SEGMENTS) 65}; 66#undef SP 67 68static struct kmem_cache *scsi_bidi_sdb_cache; 69 70static void scsi_run_queue(struct request_queue *q); 71 72/* 73 * Function: scsi_unprep_request() 74 * 75 * Purpose: Remove all preparation done for a request, including its 76 * associated scsi_cmnd, so that it can be requeued. 77 * 78 * Arguments: req - request to unprepare 79 * 80 * Lock status: Assumed that no locks are held upon entry. 81 * 82 * Returns: Nothing. 83 */ 84static void scsi_unprep_request(struct request *req) 85{ 86 struct scsi_cmnd *cmd = req->special; 87 88 req->cmd_flags &= ~REQ_DONTPREP; 89 req->special = NULL; 90 91 scsi_put_command(cmd); 92} 93 94/* 95 * Function: scsi_queue_insert() 96 * 97 * Purpose: Insert a command in the midlevel queue. 98 * 99 * Arguments: cmd - command that we are adding to queue. 100 * reason - why we are inserting command to queue. 101 * 102 * Lock status: Assumed that lock is not held upon entry. 103 * 104 * Returns: Nothing. 105 * 106 * Notes: We do this for one of two cases. Either the host is busy 107 * and it cannot accept any more commands for the time being, 108 * or the device returned QUEUE_FULL and can accept no more 109 * commands. 110 * Notes: This could be called either from an interrupt context or a 111 * normal process context. 112 */ 113int scsi_queue_insert(struct scsi_cmnd *cmd, int reason) 114{ 115 struct Scsi_Host *host = cmd->device->host; 116 struct scsi_device *device = cmd->device; 117 struct request_queue *q = device->request_queue; 118 unsigned long flags; 119 120 SCSI_LOG_MLQUEUE(1, 121 printk("Inserting command %p into mlqueue\n", cmd)); 122 123 /* 124 * Set the appropriate busy bit for the device/host. 125 * 126 * If the host/device isn't busy, assume that something actually 127 * completed, and that we should be able to queue a command now. 128 * 129 * Note that the prior mid-layer assumption that any host could 130 * always queue at least one command is now broken. The mid-layer 131 * will implement a user specifiable stall (see 132 * scsi_host.max_host_blocked and scsi_device.max_device_blocked) 133 * if a command is requeued with no other commands outstanding 134 * either for the device or for the host. 135 */ 136 if (reason == SCSI_MLQUEUE_HOST_BUSY) 137 host->host_blocked = host->max_host_blocked; 138 else if (reason == SCSI_MLQUEUE_DEVICE_BUSY) 139 device->device_blocked = device->max_device_blocked; 140 141 /* 142 * Decrement the counters, since these commands are no longer 143 * active on the host/device. 144 */ 145 scsi_device_unbusy(device); 146 147 /* 148 * Requeue this command. It will go before all other commands 149 * that are already in the queue. 150 * 151 * NOTE: there is magic here about the way the queue is plugged if 152 * we have no outstanding commands. 153 * 154 * Although we *don't* plug the queue, we call the request 155 * function. The SCSI request function detects the blocked condition 156 * and plugs the queue appropriately. 157 */ 158 spin_lock_irqsave(q->queue_lock, flags); 159 blk_requeue_request(q, cmd->request); 160 spin_unlock_irqrestore(q->queue_lock, flags); 161 162 scsi_run_queue(q); 163 164 return 0; 165} 166 167/** 168 * scsi_execute - insert request and wait for the result 169 * @sdev: scsi device 170 * @cmd: scsi command 171 * @data_direction: data direction 172 * @buffer: data buffer 173 * @bufflen: len of buffer 174 * @sense: optional sense buffer 175 * @timeout: request timeout in seconds 176 * @retries: number of times to retry request 177 * @flags: or into request flags; 178 * 179 * returns the req->errors value which is the scsi_cmnd result 180 * field. 181 */ 182int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd, 183 int data_direction, void *buffer, unsigned bufflen, 184 unsigned char *sense, int timeout, int retries, int flags) 185{ 186 struct request *req; 187 int write = (data_direction == DMA_TO_DEVICE); 188 int ret = DRIVER_ERROR << 24; 189 190 req = blk_get_request(sdev->request_queue, write, __GFP_WAIT); 191 192 if (bufflen && blk_rq_map_kern(sdev->request_queue, req, 193 buffer, bufflen, __GFP_WAIT)) 194 goto out; 195 196 req->cmd_len = COMMAND_SIZE(cmd[0]); 197 memcpy(req->cmd, cmd, req->cmd_len); 198 req->sense = sense; 199 req->sense_len = 0; 200 req->retries = retries; 201 req->timeout = timeout; 202 req->cmd_type = REQ_TYPE_BLOCK_PC; 203 req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT; 204 205 /* 206 * head injection *required* here otherwise quiesce won't work 207 */ 208 blk_execute_rq(req->q, NULL, req, 1); 209 210 ret = req->errors; 211 out: 212 blk_put_request(req); 213 214 return ret; 215} 216EXPORT_SYMBOL(scsi_execute); 217 218 219int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd, 220 int data_direction, void *buffer, unsigned bufflen, 221 struct scsi_sense_hdr *sshdr, int timeout, int retries) 222{ 223 char *sense = NULL; 224 int result; 225 226 if (sshdr) { 227 sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO); 228 if (!sense) 229 return DRIVER_ERROR << 24; 230 } 231 result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen, 232 sense, timeout, retries, 0); 233 if (sshdr) 234 scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr); 235 236 kfree(sense); 237 return result; 238} 239EXPORT_SYMBOL(scsi_execute_req); 240 241struct scsi_io_context { 242 void *data; 243 void (*done)(void *data, char *sense, int result, int resid); 244 char sense[SCSI_SENSE_BUFFERSIZE]; 245}; 246 247static struct kmem_cache *scsi_io_context_cache; 248 249static void scsi_end_async(struct request *req, int uptodate) 250{ 251 struct scsi_io_context *sioc = req->end_io_data; 252 253 if (sioc->done) 254 sioc->done(sioc->data, sioc->sense, req->errors, req->data_len); 255 256 kmem_cache_free(scsi_io_context_cache, sioc); 257 __blk_put_request(req->q, req); 258} 259 260static int scsi_merge_bio(struct request *rq, struct bio *bio) 261{ 262 struct request_queue *q = rq->q; 263 264 bio->bi_flags &= ~(1 << BIO_SEG_VALID); 265 if (rq_data_dir(rq) == WRITE) 266 bio->bi_rw |= (1 << BIO_RW); 267 blk_queue_bounce(q, &bio); 268 269 return blk_rq_append_bio(q, rq, bio); 270} 271 272static void scsi_bi_endio(struct bio *bio, int error) 273{ 274 bio_put(bio); 275} 276 277/** 278 * scsi_req_map_sg - map a scatterlist into a request 279 * @rq: request to fill 280 * @sgl: scatterlist 281 * @nsegs: number of elements 282 * @bufflen: len of buffer 283 * @gfp: memory allocation flags 284 * 285 * scsi_req_map_sg maps a scatterlist into a request so that the 286 * request can be sent to the block layer. We do not trust the scatterlist 287 * sent to use, as some ULDs use that struct to only organize the pages. 288 */ 289static int scsi_req_map_sg(struct request *rq, struct scatterlist *sgl, 290 int nsegs, unsigned bufflen, gfp_t gfp) 291{ 292 struct request_queue *q = rq->q; 293 int nr_pages = (bufflen + sgl[0].offset + PAGE_SIZE - 1) >> PAGE_SHIFT; 294 unsigned int data_len = bufflen, len, bytes, off; 295 struct scatterlist *sg; 296 struct page *page; 297 struct bio *bio = NULL; 298 int i, err, nr_vecs = 0; 299 300 for_each_sg(sgl, sg, nsegs, i) { 301 page = sg_page(sg); 302 off = sg->offset; 303 len = sg->length; 304 305 while (len > 0 && data_len > 0) { 306 /* 307 * sg sends a scatterlist that is larger than 308 * the data_len it wants transferred for certain 309 * IO sizes 310 */ 311 bytes = min_t(unsigned int, len, PAGE_SIZE - off); 312 bytes = min(bytes, data_len); 313 314 if (!bio) { 315 nr_vecs = min_t(int, BIO_MAX_PAGES, nr_pages); 316 nr_pages -= nr_vecs; 317 318 bio = bio_alloc(gfp, nr_vecs); 319 if (!bio) { 320 err = -ENOMEM; 321 goto free_bios; 322 } 323 bio->bi_end_io = scsi_bi_endio; 324 } 325 326 if (bio_add_pc_page(q, bio, page, bytes, off) != 327 bytes) { 328 bio_put(bio); 329 err = -EINVAL; 330 goto free_bios; 331 } 332 333 if (bio->bi_vcnt >= nr_vecs) { 334 err = scsi_merge_bio(rq, bio); 335 if (err) { 336 bio_endio(bio, 0); 337 goto free_bios; 338 } 339 bio = NULL; 340 } 341 342 page++; 343 len -= bytes; 344 data_len -=bytes; 345 off = 0; 346 } 347 } 348 349 rq->buffer = rq->data = NULL; 350 rq->data_len = bufflen; 351 return 0; 352 353free_bios: 354 while ((bio = rq->bio) != NULL) { 355 rq->bio = bio->bi_next; 356 /* 357 * call endio instead of bio_put incase it was bounced 358 */ 359 bio_endio(bio, 0); 360 } 361 362 return err; 363} 364 365/** 366 * scsi_execute_async - insert request 367 * @sdev: scsi device 368 * @cmd: scsi command 369 * @cmd_len: length of scsi cdb 370 * @data_direction: DMA_TO_DEVICE, DMA_FROM_DEVICE, or DMA_NONE 371 * @buffer: data buffer (this can be a kernel buffer or scatterlist) 372 * @bufflen: len of buffer 373 * @use_sg: if buffer is a scatterlist this is the number of elements 374 * @timeout: request timeout in seconds 375 * @retries: number of times to retry request 376 * @privdata: data passed to done() 377 * @done: callback function when done 378 * @gfp: memory allocation flags 379 */ 380int scsi_execute_async(struct scsi_device *sdev, const unsigned char *cmd, 381 int cmd_len, int data_direction, void *buffer, unsigned bufflen, 382 int use_sg, int timeout, int retries, void *privdata, 383 void (*done)(void *, char *, int, int), gfp_t gfp) 384{ 385 struct request *req; 386 struct scsi_io_context *sioc; 387 int err = 0; 388 int write = (data_direction == DMA_TO_DEVICE); 389 390 sioc = kmem_cache_zalloc(scsi_io_context_cache, gfp); 391 if (!sioc) 392 return DRIVER_ERROR << 24; 393 394 req = blk_get_request(sdev->request_queue, write, gfp); 395 if (!req) 396 goto free_sense; 397 req->cmd_type = REQ_TYPE_BLOCK_PC; 398 req->cmd_flags |= REQ_QUIET; 399 400 if (use_sg) 401 err = scsi_req_map_sg(req, buffer, use_sg, bufflen, gfp); 402 else if (bufflen) 403 err = blk_rq_map_kern(req->q, req, buffer, bufflen, gfp); 404 405 if (err) 406 goto free_req; 407 408 req->cmd_len = cmd_len; 409 memset(req->cmd, 0, BLK_MAX_CDB); /* ATAPI hates garbage after CDB */ 410 memcpy(req->cmd, cmd, req->cmd_len); 411 req->sense = sioc->sense; 412 req->sense_len = 0; 413 req->timeout = timeout; 414 req->retries = retries; 415 req->end_io_data = sioc; 416 417 sioc->data = privdata; 418 sioc->done = done; 419 420 blk_execute_rq_nowait(req->q, NULL, req, 1, scsi_end_async); 421 return 0; 422 423free_req: 424 blk_put_request(req); 425free_sense: 426 kmem_cache_free(scsi_io_context_cache, sioc); 427 return DRIVER_ERROR << 24; 428} 429EXPORT_SYMBOL_GPL(scsi_execute_async); 430 431/* 432 * Function: scsi_init_cmd_errh() 433 * 434 * Purpose: Initialize cmd fields related to error handling. 435 * 436 * Arguments: cmd - command that is ready to be queued. 437 * 438 * Notes: This function has the job of initializing a number of 439 * fields related to error handling. Typically this will 440 * be called once for each command, as required. 441 */ 442static void scsi_init_cmd_errh(struct scsi_cmnd *cmd) 443{ 444 cmd->serial_number = 0; 445 scsi_set_resid(cmd, 0); 446 memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE); 447 if (cmd->cmd_len == 0) 448 cmd->cmd_len = scsi_command_size(cmd->cmnd); 449} 450 451void scsi_device_unbusy(struct scsi_device *sdev) 452{ 453 struct Scsi_Host *shost = sdev->host; 454 unsigned long flags; 455 456 spin_lock_irqsave(shost->host_lock, flags); 457 shost->host_busy--; 458 if (unlikely(scsi_host_in_recovery(shost) && 459 (shost->host_failed || shost->host_eh_scheduled))) 460 scsi_eh_wakeup(shost); 461 spin_unlock(shost->host_lock); 462 spin_lock(sdev->request_queue->queue_lock); 463 sdev->device_busy--; 464 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags); 465} 466 467/* 468 * Called for single_lun devices on IO completion. Clear starget_sdev_user, 469 * and call blk_run_queue for all the scsi_devices on the target - 470 * including current_sdev first. 471 * 472 * Called with *no* scsi locks held. 473 */ 474static void scsi_single_lun_run(struct scsi_device *current_sdev) 475{ 476 struct Scsi_Host *shost = current_sdev->host; 477 struct scsi_device *sdev, *tmp; 478 struct scsi_target *starget = scsi_target(current_sdev); 479 unsigned long flags; 480 481 spin_lock_irqsave(shost->host_lock, flags); 482 starget->starget_sdev_user = NULL; 483 spin_unlock_irqrestore(shost->host_lock, flags); 484 485 /* 486 * Call blk_run_queue for all LUNs on the target, starting with 487 * current_sdev. We race with others (to set starget_sdev_user), 488 * but in most cases, we will be first. Ideally, each LU on the 489 * target would get some limited time or requests on the target. 490 */ 491 blk_run_queue(current_sdev->request_queue); 492 493 spin_lock_irqsave(shost->host_lock, flags); 494 if (starget->starget_sdev_user) 495 goto out; 496 list_for_each_entry_safe(sdev, tmp, &starget->devices, 497 same_target_siblings) { 498 if (sdev == current_sdev) 499 continue; 500 if (scsi_device_get(sdev)) 501 continue; 502 503 spin_unlock_irqrestore(shost->host_lock, flags); 504 blk_run_queue(sdev->request_queue); 505 spin_lock_irqsave(shost->host_lock, flags); 506 507 scsi_device_put(sdev); 508 } 509 out: 510 spin_unlock_irqrestore(shost->host_lock, flags); 511} 512 513/* 514 * Function: scsi_run_queue() 515 * 516 * Purpose: Select a proper request queue to serve next 517 * 518 * Arguments: q - last request's queue 519 * 520 * Returns: Nothing 521 * 522 * Notes: The previous command was completely finished, start 523 * a new one if possible. 524 */ 525static void scsi_run_queue(struct request_queue *q) 526{ 527 struct scsi_device *sdev = q->queuedata; 528 struct Scsi_Host *shost = sdev->host; 529 unsigned long flags; 530 531 if (scsi_target(sdev)->single_lun) 532 scsi_single_lun_run(sdev); 533 534 spin_lock_irqsave(shost->host_lock, flags); 535 while (!list_empty(&shost->starved_list) && 536 !shost->host_blocked && !shost->host_self_blocked && 537 !((shost->can_queue > 0) && 538 (shost->host_busy >= shost->can_queue))) { 539 540 int flagset; 541 542 /* 543 * As long as shost is accepting commands and we have 544 * starved queues, call blk_run_queue. scsi_request_fn 545 * drops the queue_lock and can add us back to the 546 * starved_list. 547 * 548 * host_lock protects the starved_list and starved_entry. 549 * scsi_request_fn must get the host_lock before checking 550 * or modifying starved_list or starved_entry. 551 */ 552 sdev = list_entry(shost->starved_list.next, 553 struct scsi_device, starved_entry); 554 list_del_init(&sdev->starved_entry); 555 spin_unlock(shost->host_lock); 556 557 spin_lock(sdev->request_queue->queue_lock); 558 flagset = test_bit(QUEUE_FLAG_REENTER, &q->queue_flags) && 559 !test_bit(QUEUE_FLAG_REENTER, 560 &sdev->request_queue->queue_flags); 561 if (flagset) 562 queue_flag_set(QUEUE_FLAG_REENTER, sdev->request_queue); 563 __blk_run_queue(sdev->request_queue); 564 if (flagset) 565 queue_flag_clear(QUEUE_FLAG_REENTER, sdev->request_queue); 566 spin_unlock(sdev->request_queue->queue_lock); 567 568 spin_lock(shost->host_lock); 569 if (unlikely(!list_empty(&sdev->starved_entry))) 570 /* 571 * sdev lost a race, and was put back on the 572 * starved list. This is unlikely but without this 573 * in theory we could loop forever. 574 */ 575 break; 576 } 577 spin_unlock_irqrestore(shost->host_lock, flags); 578 579 blk_run_queue(q); 580} 581 582/* 583 * Function: scsi_requeue_command() 584 * 585 * Purpose: Handle post-processing of completed commands. 586 * 587 * Arguments: q - queue to operate on 588 * cmd - command that may need to be requeued. 589 * 590 * Returns: Nothing 591 * 592 * Notes: After command completion, there may be blocks left 593 * over which weren't finished by the previous command 594 * this can be for a number of reasons - the main one is 595 * I/O errors in the middle of the request, in which case 596 * we need to request the blocks that come after the bad 597 * sector. 598 * Notes: Upon return, cmd is a stale pointer. 599 */ 600static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd) 601{ 602 struct request *req = cmd->request; 603 unsigned long flags; 604 605 scsi_unprep_request(req); 606 spin_lock_irqsave(q->queue_lock, flags); 607 blk_requeue_request(q, req); 608 spin_unlock_irqrestore(q->queue_lock, flags); 609 610 scsi_run_queue(q); 611} 612 613void scsi_next_command(struct scsi_cmnd *cmd) 614{ 615 struct scsi_device *sdev = cmd->device; 616 struct request_queue *q = sdev->request_queue; 617 618 /* need to hold a reference on the device before we let go of the cmd */ 619 get_device(&sdev->sdev_gendev); 620 621 scsi_put_command(cmd); 622 scsi_run_queue(q); 623 624 /* ok to remove device now */ 625 put_device(&sdev->sdev_gendev); 626} 627 628void scsi_run_host_queues(struct Scsi_Host *shost) 629{ 630 struct scsi_device *sdev; 631 632 shost_for_each_device(sdev, shost) 633 scsi_run_queue(sdev->request_queue); 634} 635 636/* 637 * Function: scsi_end_request() 638 * 639 * Purpose: Post-processing of completed commands (usually invoked at end 640 * of upper level post-processing and scsi_io_completion). 641 * 642 * Arguments: cmd - command that is complete. 643 * error - 0 if I/O indicates success, < 0 for I/O error. 644 * bytes - number of bytes of completed I/O 645 * requeue - indicates whether we should requeue leftovers. 646 * 647 * Lock status: Assumed that lock is not held upon entry. 648 * 649 * Returns: cmd if requeue required, NULL otherwise. 650 * 651 * Notes: This is called for block device requests in order to 652 * mark some number of sectors as complete. 653 * 654 * We are guaranteeing that the request queue will be goosed 655 * at some point during this call. 656 * Notes: If cmd was requeued, upon return it will be a stale pointer. 657 */ 658static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error, 659 int bytes, int requeue) 660{ 661 struct request_queue *q = cmd->device->request_queue; 662 struct request *req = cmd->request; 663 664 /* 665 * If there are blocks left over at the end, set up the command 666 * to queue the remainder of them. 667 */ 668 if (blk_end_request(req, error, bytes)) { 669 int leftover = (req->hard_nr_sectors << 9); 670 671 if (blk_pc_request(req)) 672 leftover = req->data_len; 673 674 /* kill remainder if no retrys */ 675 if (error && blk_noretry_request(req)) 676 blk_end_request(req, error, leftover); 677 else { 678 if (requeue) { 679 /* 680 * Bleah. Leftovers again. Stick the 681 * leftovers in the front of the 682 * queue, and goose the queue again. 683 */ 684 scsi_requeue_command(q, cmd); 685 cmd = NULL; 686 } 687 return cmd; 688 } 689 } 690 691 /* 692 * This will goose the queue request function at the end, so we don't 693 * need to worry about launching another command. 694 */ 695 scsi_next_command(cmd); 696 return NULL; 697} 698 699static inline unsigned int scsi_sgtable_index(unsigned short nents) 700{ 701 unsigned int index; 702 703 BUG_ON(nents > SCSI_MAX_SG_SEGMENTS); 704 705 if (nents <= 8) 706 index = 0; 707 else 708 index = get_count_order(nents) - 3; 709 710 return index; 711} 712 713static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents) 714{ 715 struct scsi_host_sg_pool *sgp; 716 717 sgp = scsi_sg_pools + scsi_sgtable_index(nents); 718 mempool_free(sgl, sgp->pool); 719} 720 721static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask) 722{ 723 struct scsi_host_sg_pool *sgp; 724 725 sgp = scsi_sg_pools + scsi_sgtable_index(nents); 726 return mempool_alloc(sgp->pool, gfp_mask); 727} 728 729static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents, 730 gfp_t gfp_mask) 731{ 732 int ret; 733 734 BUG_ON(!nents); 735 736 ret = __sg_alloc_table(&sdb->table, nents, SCSI_MAX_SG_SEGMENTS, 737 gfp_mask, scsi_sg_alloc); 738 if (unlikely(ret)) 739 __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, 740 scsi_sg_free); 741 742 return ret; 743} 744 745static void scsi_free_sgtable(struct scsi_data_buffer *sdb) 746{ 747 __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free); 748} 749 750/* 751 * Function: scsi_release_buffers() 752 * 753 * Purpose: Completion processing for block device I/O requests. 754 * 755 * Arguments: cmd - command that we are bailing. 756 * 757 * Lock status: Assumed that no lock is held upon entry. 758 * 759 * Returns: Nothing 760 * 761 * Notes: In the event that an upper level driver rejects a 762 * command, we must release resources allocated during 763 * the __init_io() function. Primarily this would involve 764 * the scatter-gather table, and potentially any bounce 765 * buffers. 766 */ 767void scsi_release_buffers(struct scsi_cmnd *cmd) 768{ 769 if (cmd->sdb.table.nents) 770 scsi_free_sgtable(&cmd->sdb); 771 772 memset(&cmd->sdb, 0, sizeof(cmd->sdb)); 773 774 if (scsi_bidi_cmnd(cmd)) { 775 struct scsi_data_buffer *bidi_sdb = 776 cmd->request->next_rq->special; 777 scsi_free_sgtable(bidi_sdb); 778 kmem_cache_free(scsi_bidi_sdb_cache, bidi_sdb); 779 cmd->request->next_rq->special = NULL; 780 } 781} 782EXPORT_SYMBOL(scsi_release_buffers); 783 784/* 785 * Bidi commands Must be complete as a whole, both sides at once. 786 * If part of the bytes were written and lld returned 787 * scsi_in()->resid and/or scsi_out()->resid this information will be left 788 * in req->data_len and req->next_rq->data_len. The upper-layer driver can 789 * decide what to do with this information. 790 */ 791static void scsi_end_bidi_request(struct scsi_cmnd *cmd) 792{ 793 struct request *req = cmd->request; 794 unsigned int dlen = req->data_len; 795 unsigned int next_dlen = req->next_rq->data_len; 796 797 req->data_len = scsi_out(cmd)->resid; 798 req->next_rq->data_len = scsi_in(cmd)->resid; 799 800 /* The req and req->next_rq have not been completed */ 801 BUG_ON(blk_end_bidi_request(req, 0, dlen, next_dlen)); 802 803 scsi_release_buffers(cmd); 804 805 /* 806 * This will goose the queue request function at the end, so we don't 807 * need to worry about launching another command. 808 */ 809 scsi_next_command(cmd); 810} 811 812/* 813 * Function: scsi_io_completion() 814 * 815 * Purpose: Completion processing for block device I/O requests. 816 * 817 * Arguments: cmd - command that is finished. 818 * 819 * Lock status: Assumed that no lock is held upon entry. 820 * 821 * Returns: Nothing 822 * 823 * Notes: This function is matched in terms of capabilities to 824 * the function that created the scatter-gather list. 825 * In other words, if there are no bounce buffers 826 * (the normal case for most drivers), we don't need 827 * the logic to deal with cleaning up afterwards. 828 * 829 * We must do one of several things here: 830 * 831 * a) Call scsi_end_request. This will finish off the 832 * specified number of sectors. If we are done, the 833 * command block will be released, and the queue 834 * function will be goosed. If we are not done, then 835 * scsi_end_request will directly goose the queue. 836 * 837 * b) We can just use scsi_requeue_command() here. This would 838 * be used if we just wanted to retry, for example. 839 */ 840void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) 841{ 842 int result = cmd->result; 843 int this_count = scsi_bufflen(cmd); 844 struct request_queue *q = cmd->device->request_queue; 845 struct request *req = cmd->request; 846 int error = 0; 847 struct scsi_sense_hdr sshdr; 848 int sense_valid = 0; 849 int sense_deferred = 0; 850 851 if (result) { 852 sense_valid = scsi_command_normalize_sense(cmd, &sshdr); 853 if (sense_valid) 854 sense_deferred = scsi_sense_is_deferred(&sshdr); 855 } 856 857 if (blk_pc_request(req)) { /* SG_IO ioctl from block level */ 858 req->errors = result; 859 if (result) { 860 if (sense_valid && req->sense) { 861 /* 862 * SG_IO wants current and deferred errors 863 */ 864 int len = 8 + cmd->sense_buffer[7]; 865 866 if (len > SCSI_SENSE_BUFFERSIZE) 867 len = SCSI_SENSE_BUFFERSIZE; 868 memcpy(req->sense, cmd->sense_buffer, len); 869 req->sense_len = len; 870 } 871 if (!sense_deferred) 872 error = -EIO; 873 } 874 if (scsi_bidi_cmnd(cmd)) { 875 /* will also release_buffers */ 876 scsi_end_bidi_request(cmd); 877 return; 878 } 879 req->data_len = scsi_get_resid(cmd); 880 } 881 882 BUG_ON(blk_bidi_rq(req)); /* bidi not support for !blk_pc_request yet */ 883 scsi_release_buffers(cmd); 884 885 /* 886 * Next deal with any sectors which we were able to correctly 887 * handle. 888 */ 889 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, " 890 "%d bytes done.\n", 891 req->nr_sectors, good_bytes)); 892 893 /* A number of bytes were successfully read. If there 894 * are leftovers and there is some kind of error 895 * (result != 0), retry the rest. 896 */ 897 if (scsi_end_request(cmd, error, good_bytes, result == 0) == NULL) 898 return; 899 900 /* good_bytes = 0, or (inclusive) there were leftovers and 901 * result = 0, so scsi_end_request couldn't retry. 902 */ 903 if (sense_valid && !sense_deferred) { 904 switch (sshdr.sense_key) { 905 case UNIT_ATTENTION: 906 if (cmd->device->removable) { 907 /* Detected disc change. Set a bit 908 * and quietly refuse further access. 909 */ 910 cmd->device->changed = 1; 911 scsi_end_request(cmd, -EIO, this_count, 1); 912 return; 913 } else { 914 /* Must have been a power glitch, or a 915 * bus reset. Could not have been a 916 * media change, so we just retry the 917 * request and see what happens. 918 */ 919 scsi_requeue_command(q, cmd); 920 return; 921 } 922 break; 923 case ILLEGAL_REQUEST: 924 /* If we had an ILLEGAL REQUEST returned, then 925 * we may have performed an unsupported 926 * command. The only thing this should be 927 * would be a ten byte read where only a six 928 * byte read was supported. Also, on a system 929 * where READ CAPACITY failed, we may have 930 * read past the end of the disk. 931 */ 932 if ((cmd->device->use_10_for_rw && 933 sshdr.asc == 0x20 && sshdr.ascq == 0x00) && 934 (cmd->cmnd[0] == READ_10 || 935 cmd->cmnd[0] == WRITE_10)) { 936 cmd->device->use_10_for_rw = 0; 937 /* This will cause a retry with a 938 * 6-byte command. 939 */ 940 scsi_requeue_command(q, cmd); 941 return; 942 } else { 943 scsi_end_request(cmd, -EIO, this_count, 1); 944 return; 945 } 946 break; 947 case NOT_READY: 948 /* If the device is in the process of becoming 949 * ready, or has a temporary blockage, retry. 950 */ 951 if (sshdr.asc == 0x04) { 952 switch (sshdr.ascq) { 953 case 0x01: /* becoming ready */ 954 case 0x04: /* format in progress */ 955 case 0x05: /* rebuild in progress */ 956 case 0x06: /* recalculation in progress */ 957 case 0x07: /* operation in progress */ 958 case 0x08: /* Long write in progress */ 959 case 0x09: /* self test in progress */ 960 scsi_requeue_command(q, cmd); 961 return; 962 default: 963 break; 964 } 965 } 966 if (!(req->cmd_flags & REQ_QUIET)) 967 scsi_cmd_print_sense_hdr(cmd, 968 "Device not ready", 969 &sshdr); 970 971 scsi_end_request(cmd, -EIO, this_count, 1); 972 return; 973 case VOLUME_OVERFLOW: 974 if (!(req->cmd_flags & REQ_QUIET)) { 975 scmd_printk(KERN_INFO, cmd, 976 "Volume overflow, CDB: "); 977 __scsi_print_command(cmd->cmnd); 978 scsi_print_sense("", cmd); 979 } 980 /* See SSC3rXX or current. */ 981 scsi_end_request(cmd, -EIO, this_count, 1); 982 return; 983 default: 984 break; 985 } 986 } 987 if (host_byte(result) == DID_RESET) { 988 /* Third party bus reset or reset for error recovery 989 * reasons. Just retry the request and see what 990 * happens. 991 */ 992 scsi_requeue_command(q, cmd); 993 return; 994 } 995 if (result) { 996 if (!(req->cmd_flags & REQ_QUIET)) { 997 scsi_print_result(cmd); 998 if (driver_byte(result) & DRIVER_SENSE) 999 scsi_print_sense("", cmd); 1000 } 1001 } 1002 scsi_end_request(cmd, -EIO, this_count, !result); 1003} 1004 1005static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb, 1006 gfp_t gfp_mask) 1007{ 1008 int count; 1009 1010 /* 1011 * If sg table allocation fails, requeue request later. 1012 */ 1013 if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments, 1014 gfp_mask))) { 1015 return BLKPREP_DEFER; 1016 } 1017 1018 req->buffer = NULL; 1019 1020 /* 1021 * Next, walk the list, and fill in the addresses and sizes of 1022 * each segment. 1023 */ 1024 count = blk_rq_map_sg(req->q, req, sdb->table.sgl); 1025 BUG_ON(count > sdb->table.nents); 1026 sdb->table.nents = count; 1027 if (blk_pc_request(req)) 1028 sdb->length = req->data_len; 1029 else 1030 sdb->length = req->nr_sectors << 9; 1031 return BLKPREP_OK; 1032} 1033 1034/* 1035 * Function: scsi_init_io() 1036 * 1037 * Purpose: SCSI I/O initialize function. 1038 * 1039 * Arguments: cmd - Command descriptor we wish to initialize 1040 * 1041 * Returns: 0 on success 1042 * BLKPREP_DEFER if the failure is retryable 1043 * BLKPREP_KILL if the failure is fatal 1044 */ 1045int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask) 1046{ 1047 int error = scsi_init_sgtable(cmd->request, &cmd->sdb, gfp_mask); 1048 if (error) 1049 goto err_exit; 1050 1051 if (blk_bidi_rq(cmd->request)) { 1052 struct scsi_data_buffer *bidi_sdb = kmem_cache_zalloc( 1053 scsi_bidi_sdb_cache, GFP_ATOMIC); 1054 if (!bidi_sdb) { 1055 error = BLKPREP_DEFER; 1056 goto err_exit; 1057 } 1058 1059 cmd->request->next_rq->special = bidi_sdb; 1060 error = scsi_init_sgtable(cmd->request->next_rq, bidi_sdb, 1061 GFP_ATOMIC); 1062 if (error) 1063 goto err_exit; 1064 } 1065 1066 return BLKPREP_OK ; 1067 1068err_exit: 1069 scsi_release_buffers(cmd); 1070 if (error == BLKPREP_KILL) 1071 scsi_put_command(cmd); 1072 else /* BLKPREP_DEFER */ 1073 scsi_unprep_request(cmd->request); 1074 1075 return error; 1076} 1077EXPORT_SYMBOL(scsi_init_io); 1078 1079static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev, 1080 struct request *req) 1081{ 1082 struct scsi_cmnd *cmd; 1083 1084 if (!req->special) { 1085 cmd = scsi_get_command(sdev, GFP_ATOMIC); 1086 if (unlikely(!cmd)) 1087 return NULL; 1088 req->special = cmd; 1089 } else { 1090 cmd = req->special; 1091 } 1092 1093 /* pull a tag out of the request if we have one */ 1094 cmd->tag = req->tag; 1095 cmd->request = req; 1096 1097 cmd->cmnd = req->cmd; 1098 1099 return cmd; 1100} 1101 1102int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req) 1103{ 1104 struct scsi_cmnd *cmd; 1105 int ret = scsi_prep_state_check(sdev, req); 1106 1107 if (ret != BLKPREP_OK) 1108 return ret; 1109 1110 cmd = scsi_get_cmd_from_req(sdev, req); 1111 if (unlikely(!cmd)) 1112 return BLKPREP_DEFER; 1113 1114 /* 1115 * BLOCK_PC requests may transfer data, in which case they must 1116 * a bio attached to them. Or they might contain a SCSI command 1117 * that does not transfer data, in which case they may optionally 1118 * submit a request without an attached bio. 1119 */ 1120 if (req->bio) { 1121 int ret; 1122 1123 BUG_ON(!req->nr_phys_segments); 1124 1125 ret = scsi_init_io(cmd, GFP_ATOMIC); 1126 if (unlikely(ret)) 1127 return ret; 1128 } else { 1129 BUG_ON(req->data_len); 1130 BUG_ON(req->data); 1131 1132 memset(&cmd->sdb, 0, sizeof(cmd->sdb)); 1133 req->buffer = NULL; 1134 } 1135 1136 cmd->cmd_len = req->cmd_len; 1137 if (!req->data_len) 1138 cmd->sc_data_direction = DMA_NONE; 1139 else if (rq_data_dir(req) == WRITE) 1140 cmd->sc_data_direction = DMA_TO_DEVICE; 1141 else 1142 cmd->sc_data_direction = DMA_FROM_DEVICE; 1143 1144 cmd->transfersize = req->data_len; 1145 cmd->allowed = req->retries; 1146 cmd->timeout_per_command = req->timeout; 1147 return BLKPREP_OK; 1148} 1149EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd); 1150 1151/* 1152 * Setup a REQ_TYPE_FS command. These are simple read/write request 1153 * from filesystems that still need to be translated to SCSI CDBs from 1154 * the ULD. 1155 */ 1156int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req) 1157{ 1158 struct scsi_cmnd *cmd; 1159 int ret = scsi_prep_state_check(sdev, req); 1160 1161 if (ret != BLKPREP_OK) 1162 return ret; 1163 /* 1164 * Filesystem requests must transfer data. 1165 */ 1166 BUG_ON(!req->nr_phys_segments); 1167 1168 cmd = scsi_get_cmd_from_req(sdev, req); 1169 if (unlikely(!cmd)) 1170 return BLKPREP_DEFER; 1171 1172 memset(cmd->cmnd, 0, BLK_MAX_CDB); 1173 return scsi_init_io(cmd, GFP_ATOMIC); 1174} 1175EXPORT_SYMBOL(scsi_setup_fs_cmnd); 1176 1177int scsi_prep_state_check(struct scsi_device *sdev, struct request *req) 1178{ 1179 int ret = BLKPREP_OK; 1180 1181 /* 1182 * If the device is not in running state we will reject some 1183 * or all commands. 1184 */ 1185 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) { 1186 switch (sdev->sdev_state) { 1187 case SDEV_OFFLINE: 1188 /* 1189 * If the device is offline we refuse to process any 1190 * commands. The device must be brought online 1191 * before trying any recovery commands. 1192 */ 1193 sdev_printk(KERN_ERR, sdev, 1194 "rejecting I/O to offline device\n"); 1195 ret = BLKPREP_KILL; 1196 break; 1197 case SDEV_DEL: 1198 /* 1199 * If the device is fully deleted, we refuse to 1200 * process any commands as well. 1201 */ 1202 sdev_printk(KERN_ERR, sdev, 1203 "rejecting I/O to dead device\n"); 1204 ret = BLKPREP_KILL; 1205 break; 1206 case SDEV_QUIESCE: 1207 case SDEV_BLOCK: 1208 /* 1209 * If the devices is blocked we defer normal commands. 1210 */ 1211 if (!(req->cmd_flags & REQ_PREEMPT)) 1212 ret = BLKPREP_DEFER; 1213 break; 1214 default: 1215 /* 1216 * For any other not fully online state we only allow 1217 * special commands. In particular any user initiated 1218 * command is not allowed. 1219 */ 1220 if (!(req->cmd_flags & REQ_PREEMPT)) 1221 ret = BLKPREP_KILL; 1222 break; 1223 } 1224 } 1225 return ret; 1226} 1227EXPORT_SYMBOL(scsi_prep_state_check); 1228 1229int scsi_prep_return(struct request_queue *q, struct request *req, int ret) 1230{ 1231 struct scsi_device *sdev = q->queuedata; 1232 1233 switch (ret) { 1234 case BLKPREP_KILL: 1235 req->errors = DID_NO_CONNECT << 16; 1236 /* release the command and kill it */ 1237 if (req->special) { 1238 struct scsi_cmnd *cmd = req->special; 1239 scsi_release_buffers(cmd); 1240 scsi_put_command(cmd); 1241 req->special = NULL; 1242 } 1243 break; 1244 case BLKPREP_DEFER: 1245 /* 1246 * If we defer, the elv_next_request() returns NULL, but the 1247 * queue must be restarted, so we plug here if no returning 1248 * command will automatically do that. 1249 */ 1250 if (sdev->device_busy == 0) 1251 blk_plug_device(q); 1252 break; 1253 default: 1254 req->cmd_flags |= REQ_DONTPREP; 1255 } 1256 1257 return ret; 1258} 1259EXPORT_SYMBOL(scsi_prep_return); 1260 1261int scsi_prep_fn(struct request_queue *q, struct request *req) 1262{ 1263 struct scsi_device *sdev = q->queuedata; 1264 int ret = BLKPREP_KILL; 1265 1266 if (req->cmd_type == REQ_TYPE_BLOCK_PC) 1267 ret = scsi_setup_blk_pc_cmnd(sdev, req); 1268 return scsi_prep_return(q, req, ret); 1269} 1270 1271/* 1272 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else 1273 * return 0. 1274 * 1275 * Called with the queue_lock held. 1276 */ 1277static inline int scsi_dev_queue_ready(struct request_queue *q, 1278 struct scsi_device *sdev) 1279{ 1280 if (sdev->device_busy >= sdev->queue_depth) 1281 return 0; 1282 if (sdev->device_busy == 0 && sdev->device_blocked) { 1283 /* 1284 * unblock after device_blocked iterates to zero 1285 */ 1286 if (--sdev->device_blocked == 0) { 1287 SCSI_LOG_MLQUEUE(3, 1288 sdev_printk(KERN_INFO, sdev, 1289 "unblocking device at zero depth\n")); 1290 } else { 1291 blk_plug_device(q); 1292 return 0; 1293 } 1294 } 1295 if (sdev->device_blocked) 1296 return 0; 1297 1298 return 1; 1299} 1300 1301/* 1302 * scsi_host_queue_ready: if we can send requests to shost, return 1 else 1303 * return 0. We must end up running the queue again whenever 0 is 1304 * returned, else IO can hang. 1305 * 1306 * Called with host_lock held. 1307 */ 1308static inline int scsi_host_queue_ready(struct request_queue *q, 1309 struct Scsi_Host *shost, 1310 struct scsi_device *sdev) 1311{ 1312 if (scsi_host_in_recovery(shost)) 1313 return 0; 1314 if (shost->host_busy == 0 && shost->host_blocked) { 1315 /* 1316 * unblock after host_blocked iterates to zero 1317 */ 1318 if (--shost->host_blocked == 0) { 1319 SCSI_LOG_MLQUEUE(3, 1320 printk("scsi%d unblocking host at zero depth\n", 1321 shost->host_no)); 1322 } else { 1323 blk_plug_device(q); 1324 return 0; 1325 } 1326 } 1327 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) || 1328 shost->host_blocked || shost->host_self_blocked) { 1329 if (list_empty(&sdev->starved_entry)) 1330 list_add_tail(&sdev->starved_entry, &shost->starved_list); 1331 return 0; 1332 } 1333 1334 /* We're OK to process the command, so we can't be starved */ 1335 if (!list_empty(&sdev->starved_entry)) 1336 list_del_init(&sdev->starved_entry); 1337 1338 return 1; 1339} 1340 1341/* 1342 * Kill a request for a dead device 1343 */ 1344static void scsi_kill_request(struct request *req, struct request_queue *q) 1345{ 1346 struct scsi_cmnd *cmd = req->special; 1347 struct scsi_device *sdev = cmd->device; 1348 struct Scsi_Host *shost = sdev->host; 1349 1350 blkdev_dequeue_request(req); 1351 1352 if (unlikely(cmd == NULL)) { 1353 printk(KERN_CRIT "impossible request in %s.\n", 1354 __FUNCTION__); 1355 BUG(); 1356 } 1357 1358 scsi_init_cmd_errh(cmd); 1359 cmd->result = DID_NO_CONNECT << 16; 1360 atomic_inc(&cmd->device->iorequest_cnt); 1361 1362 /* 1363 * SCSI request completion path will do scsi_device_unbusy(), 1364 * bump busy counts. To bump the counters, we need to dance 1365 * with the locks as normal issue path does. 1366 */ 1367 sdev->device_busy++; 1368 spin_unlock(sdev->request_queue->queue_lock); 1369 spin_lock(shost->host_lock); 1370 shost->host_busy++; 1371 spin_unlock(shost->host_lock); 1372 spin_lock(sdev->request_queue->queue_lock); 1373 1374 __scsi_done(cmd); 1375} 1376 1377static void scsi_softirq_done(struct request *rq) 1378{ 1379 struct scsi_cmnd *cmd = rq->completion_data; 1380 unsigned long wait_for = (cmd->allowed + 1) * cmd->timeout_per_command; 1381 int disposition; 1382 1383 INIT_LIST_HEAD(&cmd->eh_entry); 1384 1385 disposition = scsi_decide_disposition(cmd); 1386 if (disposition != SUCCESS && 1387 time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) { 1388 sdev_printk(KERN_ERR, cmd->device, 1389 "timing out command, waited %lus\n", 1390 wait_for/HZ); 1391 disposition = SUCCESS; 1392 } 1393 1394 scsi_log_completion(cmd, disposition); 1395 1396 switch (disposition) { 1397 case SUCCESS: 1398 scsi_finish_command(cmd); 1399 break; 1400 case NEEDS_RETRY: 1401 scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY); 1402 break; 1403 case ADD_TO_MLQUEUE: 1404 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY); 1405 break; 1406 default: 1407 if (!scsi_eh_scmd_add(cmd, 0)) 1408 scsi_finish_command(cmd); 1409 } 1410} 1411 1412/* 1413 * Function: scsi_request_fn() 1414 * 1415 * Purpose: Main strategy routine for SCSI. 1416 * 1417 * Arguments: q - Pointer to actual queue. 1418 * 1419 * Returns: Nothing 1420 * 1421 * Lock status: IO request lock assumed to be held when called. 1422 */ 1423static void scsi_request_fn(struct request_queue *q) 1424{ 1425 struct scsi_device *sdev = q->queuedata; 1426 struct Scsi_Host *shost; 1427 struct scsi_cmnd *cmd; 1428 struct request *req; 1429 1430 if (!sdev) { 1431 printk("scsi: killing requests for dead queue\n"); 1432 while ((req = elv_next_request(q)) != NULL) 1433 scsi_kill_request(req, q); 1434 return; 1435 } 1436 1437 if(!get_device(&sdev->sdev_gendev)) 1438 /* We must be tearing the block queue down already */ 1439 return; 1440 1441 /* 1442 * To start with, we keep looping until the queue is empty, or until 1443 * the host is no longer able to accept any more requests. 1444 */ 1445 shost = sdev->host; 1446 while (!blk_queue_plugged(q)) { 1447 int rtn; 1448 /* 1449 * get next queueable request. We do this early to make sure 1450 * that the request is fully prepared even if we cannot 1451 * accept it. 1452 */ 1453 req = elv_next_request(q); 1454 if (!req || !scsi_dev_queue_ready(q, sdev)) 1455 break; 1456 1457 if (unlikely(!scsi_device_online(sdev))) { 1458 sdev_printk(KERN_ERR, sdev, 1459 "rejecting I/O to offline device\n"); 1460 scsi_kill_request(req, q); 1461 continue; 1462 } 1463 1464 1465 /* 1466 * Remove the request from the request list. 1467 */ 1468 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req))) 1469 blkdev_dequeue_request(req); 1470 sdev->device_busy++; 1471 1472 spin_unlock(q->queue_lock); 1473 cmd = req->special; 1474 if (unlikely(cmd == NULL)) { 1475 printk(KERN_CRIT "impossible request in %s.\n" 1476 "please mail a stack trace to " 1477 "linux-scsi@vger.kernel.org\n", 1478 __FUNCTION__); 1479 blk_dump_rq_flags(req, "foo"); 1480 BUG(); 1481 } 1482 spin_lock(shost->host_lock); 1483 1484 if (!scsi_host_queue_ready(q, shost, sdev)) 1485 goto not_ready; 1486 if (scsi_target(sdev)->single_lun) { 1487 if (scsi_target(sdev)->starget_sdev_user && 1488 scsi_target(sdev)->starget_sdev_user != sdev) 1489 goto not_ready; 1490 scsi_target(sdev)->starget_sdev_user = sdev; 1491 } 1492 shost->host_busy++; 1493 1494 /* 1495 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will 1496 * take the lock again. 1497 */ 1498 spin_unlock_irq(shost->host_lock); 1499 1500 /* 1501 * Finally, initialize any error handling parameters, and set up 1502 * the timers for timeouts. 1503 */ 1504 scsi_init_cmd_errh(cmd); 1505 1506 /* 1507 * Dispatch the command to the low-level driver. 1508 */ 1509 rtn = scsi_dispatch_cmd(cmd); 1510 spin_lock_irq(q->queue_lock); 1511 if(rtn) { 1512 /* we're refusing the command; because of 1513 * the way locks get dropped, we need to 1514 * check here if plugging is required */ 1515 if(sdev->device_busy == 0) 1516 blk_plug_device(q); 1517 1518 break; 1519 } 1520 } 1521 1522 goto out; 1523 1524 not_ready: 1525 spin_unlock_irq(shost->host_lock); 1526 1527 /* 1528 * lock q, handle tag, requeue req, and decrement device_busy. We 1529 * must return with queue_lock held. 1530 * 1531 * Decrementing device_busy without checking it is OK, as all such 1532 * cases (host limits or settings) should run the queue at some 1533 * later time. 1534 */ 1535 spin_lock_irq(q->queue_lock); 1536 blk_requeue_request(q, req); 1537 sdev->device_busy--; 1538 if(sdev->device_busy == 0) 1539 blk_plug_device(q); 1540 out: 1541 /* must be careful here...if we trigger the ->remove() function 1542 * we cannot be holding the q lock */ 1543 spin_unlock_irq(q->queue_lock); 1544 put_device(&sdev->sdev_gendev); 1545 spin_lock_irq(q->queue_lock); 1546} 1547 1548u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost) 1549{ 1550 struct device *host_dev; 1551 u64 bounce_limit = 0xffffffff; 1552 1553 if (shost->unchecked_isa_dma) 1554 return BLK_BOUNCE_ISA; 1555 /* 1556 * Platforms with virtual-DMA translation 1557 * hardware have no practical limit. 1558 */ 1559 if (!PCI_DMA_BUS_IS_PHYS) 1560 return BLK_BOUNCE_ANY; 1561 1562 host_dev = scsi_get_device(shost); 1563 if (host_dev && host_dev->dma_mask) 1564 bounce_limit = *host_dev->dma_mask; 1565 1566 return bounce_limit; 1567} 1568EXPORT_SYMBOL(scsi_calculate_bounce_limit); 1569 1570struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost, 1571 request_fn_proc *request_fn) 1572{ 1573 struct request_queue *q; 1574 struct device *dev = shost->shost_gendev.parent; 1575 1576 q = blk_init_queue(request_fn, NULL); 1577 if (!q) 1578 return NULL; 1579 1580 /* 1581 * this limit is imposed by hardware restrictions 1582 */ 1583 blk_queue_max_hw_segments(q, shost->sg_tablesize); 1584 blk_queue_max_phys_segments(q, SCSI_MAX_SG_CHAIN_SEGMENTS); 1585 1586 blk_queue_max_sectors(q, shost->max_sectors); 1587 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost)); 1588 blk_queue_segment_boundary(q, shost->dma_boundary); 1589 dma_set_seg_boundary(dev, shost->dma_boundary); 1590 1591 blk_queue_max_segment_size(q, dma_get_max_seg_size(dev)); 1592 1593 /* New queue, no concurrency on queue_flags */ 1594 if (!shost->use_clustering) 1595 queue_flag_clear_unlocked(QUEUE_FLAG_CLUSTER, q); 1596 1597 /* 1598 * set a reasonable default alignment on word boundaries: the 1599 * host and device may alter it using 1600 * blk_queue_update_dma_alignment() later. 1601 */ 1602 blk_queue_dma_alignment(q, 0x03); 1603 1604 return q; 1605} 1606EXPORT_SYMBOL(__scsi_alloc_queue); 1607 1608struct request_queue *scsi_alloc_queue(struct scsi_device *sdev) 1609{ 1610 struct request_queue *q; 1611 1612 q = __scsi_alloc_queue(sdev->host, scsi_request_fn); 1613 if (!q) 1614 return NULL; 1615 1616 blk_queue_prep_rq(q, scsi_prep_fn); 1617 blk_queue_softirq_done(q, scsi_softirq_done); 1618 return q; 1619} 1620 1621void scsi_free_queue(struct request_queue *q) 1622{ 1623 blk_cleanup_queue(q); 1624} 1625 1626/* 1627 * Function: scsi_block_requests() 1628 * 1629 * Purpose: Utility function used by low-level drivers to prevent further 1630 * commands from being queued to the device. 1631 * 1632 * Arguments: shost - Host in question 1633 * 1634 * Returns: Nothing 1635 * 1636 * Lock status: No locks are assumed held. 1637 * 1638 * Notes: There is no timer nor any other means by which the requests 1639 * get unblocked other than the low-level driver calling 1640 * scsi_unblock_requests(). 1641 */ 1642void scsi_block_requests(struct Scsi_Host *shost) 1643{ 1644 shost->host_self_blocked = 1; 1645} 1646EXPORT_SYMBOL(scsi_block_requests); 1647 1648/* 1649 * Function: scsi_unblock_requests() 1650 * 1651 * Purpose: Utility function used by low-level drivers to allow further 1652 * commands from being queued to the device. 1653 * 1654 * Arguments: shost - Host in question 1655 * 1656 * Returns: Nothing 1657 * 1658 * Lock status: No locks are assumed held. 1659 * 1660 * Notes: There is no timer nor any other means by which the requests 1661 * get unblocked other than the low-level driver calling 1662 * scsi_unblock_requests(). 1663 * 1664 * This is done as an API function so that changes to the 1665 * internals of the scsi mid-layer won't require wholesale 1666 * changes to drivers that use this feature. 1667 */ 1668void scsi_unblock_requests(struct Scsi_Host *shost) 1669{ 1670 shost->host_self_blocked = 0; 1671 scsi_run_host_queues(shost); 1672} 1673EXPORT_SYMBOL(scsi_unblock_requests); 1674 1675int __init scsi_init_queue(void) 1676{ 1677 int i; 1678 1679 scsi_io_context_cache = kmem_cache_create("scsi_io_context", 1680 sizeof(struct scsi_io_context), 1681 0, 0, NULL); 1682 if (!scsi_io_context_cache) { 1683 printk(KERN_ERR "SCSI: can't init scsi io context cache\n"); 1684 return -ENOMEM; 1685 } 1686 1687 scsi_bidi_sdb_cache = kmem_cache_create("scsi_bidi_sdb", 1688 sizeof(struct scsi_data_buffer), 1689 0, 0, NULL); 1690 if (!scsi_bidi_sdb_cache) { 1691 printk(KERN_ERR "SCSI: can't init scsi bidi sdb cache\n"); 1692 goto cleanup_io_context; 1693 } 1694 1695 for (i = 0; i < SG_MEMPOOL_NR; i++) { 1696 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i; 1697 int size = sgp->size * sizeof(struct scatterlist); 1698 1699 sgp->slab = kmem_cache_create(sgp->name, size, 0, 1700 SLAB_HWCACHE_ALIGN, NULL); 1701 if (!sgp->slab) { 1702 printk(KERN_ERR "SCSI: can't init sg slab %s\n", 1703 sgp->name); 1704 goto cleanup_bidi_sdb; 1705 } 1706 1707 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE, 1708 sgp->slab); 1709 if (!sgp->pool) { 1710 printk(KERN_ERR "SCSI: can't init sg mempool %s\n", 1711 sgp->name); 1712 goto cleanup_bidi_sdb; 1713 } 1714 } 1715 1716 return 0; 1717 1718cleanup_bidi_sdb: 1719 for (i = 0; i < SG_MEMPOOL_NR; i++) { 1720 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i; 1721 if (sgp->pool) 1722 mempool_destroy(sgp->pool); 1723 if (sgp->slab) 1724 kmem_cache_destroy(sgp->slab); 1725 } 1726 kmem_cache_destroy(scsi_bidi_sdb_cache); 1727cleanup_io_context: 1728 kmem_cache_destroy(scsi_io_context_cache); 1729 1730 return -ENOMEM; 1731} 1732 1733void scsi_exit_queue(void) 1734{ 1735 int i; 1736 1737 kmem_cache_destroy(scsi_io_context_cache); 1738 kmem_cache_destroy(scsi_bidi_sdb_cache); 1739 1740 for (i = 0; i < SG_MEMPOOL_NR; i++) { 1741 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i; 1742 mempool_destroy(sgp->pool); 1743 kmem_cache_destroy(sgp->slab); 1744 } 1745} 1746 1747/** 1748 * scsi_mode_select - issue a mode select 1749 * @sdev: SCSI device to be queried 1750 * @pf: Page format bit (1 == standard, 0 == vendor specific) 1751 * @sp: Save page bit (0 == don't save, 1 == save) 1752 * @modepage: mode page being requested 1753 * @buffer: request buffer (may not be smaller than eight bytes) 1754 * @len: length of request buffer. 1755 * @timeout: command timeout 1756 * @retries: number of retries before failing 1757 * @data: returns a structure abstracting the mode header data 1758 * @sshdr: place to put sense data (or NULL if no sense to be collected). 1759 * must be SCSI_SENSE_BUFFERSIZE big. 1760 * 1761 * Returns zero if successful; negative error number or scsi 1762 * status on error 1763 * 1764 */ 1765int 1766scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage, 1767 unsigned char *buffer, int len, int timeout, int retries, 1768 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr) 1769{ 1770 unsigned char cmd[10]; 1771 unsigned char *real_buffer; 1772 int ret; 1773 1774 memset(cmd, 0, sizeof(cmd)); 1775 cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0); 1776 1777 if (sdev->use_10_for_ms) { 1778 if (len > 65535) 1779 return -EINVAL; 1780 real_buffer = kmalloc(8 + len, GFP_KERNEL); 1781 if (!real_buffer) 1782 return -ENOMEM; 1783 memcpy(real_buffer + 8, buffer, len); 1784 len += 8; 1785 real_buffer[0] = 0; 1786 real_buffer[1] = 0; 1787 real_buffer[2] = data->medium_type; 1788 real_buffer[3] = data->device_specific; 1789 real_buffer[4] = data->longlba ? 0x01 : 0; 1790 real_buffer[5] = 0; 1791 real_buffer[6] = data->block_descriptor_length >> 8; 1792 real_buffer[7] = data->block_descriptor_length; 1793 1794 cmd[0] = MODE_SELECT_10; 1795 cmd[7] = len >> 8; 1796 cmd[8] = len; 1797 } else { 1798 if (len > 255 || data->block_descriptor_length > 255 || 1799 data->longlba) 1800 return -EINVAL; 1801 1802 real_buffer = kmalloc(4 + len, GFP_KERNEL); 1803 if (!real_buffer) 1804 return -ENOMEM; 1805 memcpy(real_buffer + 4, buffer, len); 1806 len += 4; 1807 real_buffer[0] = 0; 1808 real_buffer[1] = data->medium_type; 1809 real_buffer[2] = data->device_specific; 1810 real_buffer[3] = data->block_descriptor_length; 1811 1812 1813 cmd[0] = MODE_SELECT; 1814 cmd[4] = len; 1815 } 1816 1817 ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len, 1818 sshdr, timeout, retries); 1819 kfree(real_buffer); 1820 return ret; 1821} 1822EXPORT_SYMBOL_GPL(scsi_mode_select); 1823 1824/** 1825 * scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary. 1826 * @sdev: SCSI device to be queried 1827 * @dbd: set if mode sense will allow block descriptors to be returned 1828 * @modepage: mode page being requested 1829 * @buffer: request buffer (may not be smaller than eight bytes) 1830 * @len: length of request buffer. 1831 * @timeout: command timeout 1832 * @retries: number of retries before failing 1833 * @data: returns a structure abstracting the mode header data 1834 * @sshdr: place to put sense data (or NULL if no sense to be collected). 1835 * must be SCSI_SENSE_BUFFERSIZE big. 1836 * 1837 * Returns zero if unsuccessful, or the header offset (either 4 1838 * or 8 depending on whether a six or ten byte command was 1839 * issued) if successful. 1840 */ 1841int 1842scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage, 1843 unsigned char *buffer, int len, int timeout, int retries, 1844 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr) 1845{ 1846 unsigned char cmd[12]; 1847 int use_10_for_ms; 1848 int header_length; 1849 int result; 1850 struct scsi_sense_hdr my_sshdr; 1851 1852 memset(data, 0, sizeof(*data)); 1853 memset(&cmd[0], 0, 12); 1854 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */ 1855 cmd[2] = modepage; 1856 1857 /* caller might not be interested in sense, but we need it */ 1858 if (!sshdr) 1859 sshdr = &my_sshdr; 1860 1861 retry: 1862 use_10_for_ms = sdev->use_10_for_ms; 1863 1864 if (use_10_for_ms) { 1865 if (len < 8) 1866 len = 8; 1867 1868 cmd[0] = MODE_SENSE_10; 1869 cmd[8] = len; 1870 header_length = 8; 1871 } else { 1872 if (len < 4) 1873 len = 4; 1874 1875 cmd[0] = MODE_SENSE; 1876 cmd[4] = len; 1877 header_length = 4; 1878 } 1879 1880 memset(buffer, 0, len); 1881 1882 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len, 1883 sshdr, timeout, retries); 1884 1885 /* This code looks awful: what it's doing is making sure an 1886 * ILLEGAL REQUEST sense return identifies the actual command 1887 * byte as the problem. MODE_SENSE commands can return 1888 * ILLEGAL REQUEST if the code page isn't supported */ 1889 1890 if (use_10_for_ms && !scsi_status_is_good(result) && 1891 (driver_byte(result) & DRIVER_SENSE)) { 1892 if (scsi_sense_valid(sshdr)) { 1893 if ((sshdr->sense_key == ILLEGAL_REQUEST) && 1894 (sshdr->asc == 0x20) && (sshdr->ascq == 0)) { 1895 /* 1896 * Invalid command operation code 1897 */ 1898 sdev->use_10_for_ms = 0; 1899 goto retry; 1900 } 1901 } 1902 } 1903 1904 if(scsi_status_is_good(result)) { 1905 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b && 1906 (modepage == 6 || modepage == 8))) { 1907 /* Initio breakage? */ 1908 header_length = 0; 1909 data->length = 13; 1910 data->medium_type = 0; 1911 data->device_specific = 0; 1912 data->longlba = 0; 1913 data->block_descriptor_length = 0; 1914 } else if(use_10_for_ms) { 1915 data->length = buffer[0]*256 + buffer[1] + 2; 1916 data->medium_type = buffer[2]; 1917 data->device_specific = buffer[3]; 1918 data->longlba = buffer[4] & 0x01; 1919 data->block_descriptor_length = buffer[6]*256 1920 + buffer[7]; 1921 } else { 1922 data->length = buffer[0] + 1; 1923 data->medium_type = buffer[1]; 1924 data->device_specific = buffer[2]; 1925 data->block_descriptor_length = buffer[3]; 1926 } 1927 data->header_length = header_length; 1928 } 1929 1930 return result; 1931} 1932EXPORT_SYMBOL(scsi_mode_sense); 1933 1934/** 1935 * scsi_test_unit_ready - test if unit is ready 1936 * @sdev: scsi device to change the state of. 1937 * @timeout: command timeout 1938 * @retries: number of retries before failing 1939 * @sshdr_external: Optional pointer to struct scsi_sense_hdr for 1940 * returning sense. Make sure that this is cleared before passing 1941 * in. 1942 * 1943 * Returns zero if unsuccessful or an error if TUR failed. For 1944 * removable media, a return of NOT_READY or UNIT_ATTENTION is 1945 * translated to success, with the ->changed flag updated. 1946 **/ 1947int 1948scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries, 1949 struct scsi_sense_hdr *sshdr_external) 1950{ 1951 char cmd[] = { 1952 TEST_UNIT_READY, 0, 0, 0, 0, 0, 1953 }; 1954 struct scsi_sense_hdr *sshdr; 1955 int result; 1956 1957 if (!sshdr_external) 1958 sshdr = kzalloc(sizeof(*sshdr), GFP_KERNEL); 1959 else 1960 sshdr = sshdr_external; 1961 1962 /* try to eat the UNIT_ATTENTION if there are enough retries */ 1963 do { 1964 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr, 1965 timeout, retries); 1966 } while ((driver_byte(result) & DRIVER_SENSE) && 1967 sshdr && sshdr->sense_key == UNIT_ATTENTION && 1968 --retries); 1969 1970 if (!sshdr) 1971 /* could not allocate sense buffer, so can't process it */ 1972 return result; 1973 1974 if ((driver_byte(result) & DRIVER_SENSE) && sdev->removable) { 1975 1976 if ((scsi_sense_valid(sshdr)) && 1977 ((sshdr->sense_key == UNIT_ATTENTION) || 1978 (sshdr->sense_key == NOT_READY))) { 1979 sdev->changed = 1; 1980 result = 0; 1981 } 1982 } 1983 if (!sshdr_external) 1984 kfree(sshdr); 1985 return result; 1986} 1987EXPORT_SYMBOL(scsi_test_unit_ready); 1988 1989/** 1990 * scsi_device_set_state - Take the given device through the device state model. 1991 * @sdev: scsi device to change the state of. 1992 * @state: state to change to. 1993 * 1994 * Returns zero if unsuccessful or an error if the requested 1995 * transition is illegal. 1996 */ 1997int 1998scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state) 1999{ 2000 enum scsi_device_state oldstate = sdev->sdev_state; 2001 2002 if (state == oldstate) 2003 return 0; 2004 2005 switch (state) { 2006 case SDEV_CREATED: 2007 /* There are no legal states that come back to 2008 * created. This is the manually initialised start 2009 * state */ 2010 goto illegal; 2011 2012 case SDEV_RUNNING: 2013 switch (oldstate) { 2014 case SDEV_CREATED: 2015 case SDEV_OFFLINE: 2016 case SDEV_QUIESCE: 2017 case SDEV_BLOCK: 2018 break; 2019 default: 2020 goto illegal; 2021 } 2022 break; 2023 2024 case SDEV_QUIESCE: 2025 switch (oldstate) { 2026 case SDEV_RUNNING: 2027 case SDEV_OFFLINE: 2028 break; 2029 default: 2030 goto illegal; 2031 } 2032 break; 2033 2034 case SDEV_OFFLINE: 2035 switch (oldstate) { 2036 case SDEV_CREATED: 2037 case SDEV_RUNNING: 2038 case SDEV_QUIESCE: 2039 case SDEV_BLOCK: 2040 break; 2041 default: 2042 goto illegal; 2043 } 2044 break; 2045 2046 case SDEV_BLOCK: 2047 switch (oldstate) { 2048 case SDEV_CREATED: 2049 case SDEV_RUNNING: 2050 break; 2051 default: 2052 goto illegal; 2053 } 2054 break; 2055 2056 case SDEV_CANCEL: 2057 switch (oldstate) { 2058 case SDEV_CREATED: 2059 case SDEV_RUNNING: 2060 case SDEV_QUIESCE: 2061 case SDEV_OFFLINE: 2062 case SDEV_BLOCK: 2063 break; 2064 default: 2065 goto illegal; 2066 } 2067 break; 2068 2069 case SDEV_DEL: 2070 switch (oldstate) { 2071 case SDEV_CREATED: 2072 case SDEV_RUNNING: 2073 case SDEV_OFFLINE: 2074 case SDEV_CANCEL: 2075 break; 2076 default: 2077 goto illegal; 2078 } 2079 break; 2080 2081 } 2082 sdev->sdev_state = state; 2083 return 0; 2084 2085 illegal: 2086 SCSI_LOG_ERROR_RECOVERY(1, 2087 sdev_printk(KERN_ERR, sdev, 2088 "Illegal state transition %s->%s\n", 2089 scsi_device_state_name(oldstate), 2090 scsi_device_state_name(state)) 2091 ); 2092 return -EINVAL; 2093} 2094EXPORT_SYMBOL(scsi_device_set_state); 2095 2096/** 2097 * sdev_evt_emit - emit a single SCSI device uevent 2098 * @sdev: associated SCSI device 2099 * @evt: event to emit 2100 * 2101 * Send a single uevent (scsi_event) to the associated scsi_device. 2102 */ 2103static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt) 2104{ 2105 int idx = 0; 2106 char *envp[3]; 2107 2108 switch (evt->evt_type) { 2109 case SDEV_EVT_MEDIA_CHANGE: 2110 envp[idx++] = "SDEV_MEDIA_CHANGE=1"; 2111 break; 2112 2113 default: 2114 /* do nothing */ 2115 break; 2116 } 2117 2118 envp[idx++] = NULL; 2119 2120 kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp); 2121} 2122 2123/** 2124 * sdev_evt_thread - send a uevent for each scsi event 2125 * @work: work struct for scsi_device 2126 * 2127 * Dispatch queued events to their associated scsi_device kobjects 2128 * as uevents. 2129 */ 2130void scsi_evt_thread(struct work_struct *work) 2131{ 2132 struct scsi_device *sdev; 2133 LIST_HEAD(event_list); 2134 2135 sdev = container_of(work, struct scsi_device, event_work); 2136 2137 while (1) { 2138 struct scsi_event *evt; 2139 struct list_head *this, *tmp; 2140 unsigned long flags; 2141 2142 spin_lock_irqsave(&sdev->list_lock, flags); 2143 list_splice_init(&sdev->event_list, &event_list); 2144 spin_unlock_irqrestore(&sdev->list_lock, flags); 2145 2146 if (list_empty(&event_list)) 2147 break; 2148 2149 list_for_each_safe(this, tmp, &event_list) { 2150 evt = list_entry(this, struct scsi_event, node); 2151 list_del(&evt->node); 2152 scsi_evt_emit(sdev, evt); 2153 kfree(evt); 2154 } 2155 } 2156} 2157 2158/** 2159 * sdev_evt_send - send asserted event to uevent thread 2160 * @sdev: scsi_device event occurred on 2161 * @evt: event to send 2162 * 2163 * Assert scsi device event asynchronously. 2164 */ 2165void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt) 2166{ 2167 unsigned long flags; 2168 2169#if 0 2170 /* FIXME: currently this check eliminates all media change events 2171 * for polled devices. Need to update to discriminate between AN 2172 * and polled events */ 2173 if (!test_bit(evt->evt_type, sdev->supported_events)) { 2174 kfree(evt); 2175 return; 2176 } 2177#endif 2178 2179 spin_lock_irqsave(&sdev->list_lock, flags); 2180 list_add_tail(&evt->node, &sdev->event_list); 2181 schedule_work(&sdev->event_work); 2182 spin_unlock_irqrestore(&sdev->list_lock, flags); 2183} 2184EXPORT_SYMBOL_GPL(sdev_evt_send); 2185 2186/** 2187 * sdev_evt_alloc - allocate a new scsi event 2188 * @evt_type: type of event to allocate 2189 * @gfpflags: GFP flags for allocation 2190 * 2191 * Allocates and returns a new scsi_event. 2192 */ 2193struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type, 2194 gfp_t gfpflags) 2195{ 2196 struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags); 2197 if (!evt) 2198 return NULL; 2199 2200 evt->evt_type = evt_type; 2201 INIT_LIST_HEAD(&evt->node); 2202 2203 /* evt_type-specific initialization, if any */ 2204 switch (evt_type) { 2205 case SDEV_EVT_MEDIA_CHANGE: 2206 default: 2207 /* do nothing */ 2208 break; 2209 } 2210 2211 return evt; 2212} 2213EXPORT_SYMBOL_GPL(sdev_evt_alloc); 2214 2215/** 2216 * sdev_evt_send_simple - send asserted event to uevent thread 2217 * @sdev: scsi_device event occurred on 2218 * @evt_type: type of event to send 2219 * @gfpflags: GFP flags for allocation 2220 * 2221 * Assert scsi device event asynchronously, given an event type. 2222 */ 2223void sdev_evt_send_simple(struct scsi_device *sdev, 2224 enum scsi_device_event evt_type, gfp_t gfpflags) 2225{ 2226 struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags); 2227 if (!evt) { 2228 sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n", 2229 evt_type); 2230 return; 2231 } 2232 2233 sdev_evt_send(sdev, evt); 2234} 2235EXPORT_SYMBOL_GPL(sdev_evt_send_simple); 2236 2237/** 2238 * scsi_device_quiesce - Block user issued commands. 2239 * @sdev: scsi device to quiesce. 2240 * 2241 * This works by trying to transition to the SDEV_QUIESCE state 2242 * (which must be a legal transition). When the device is in this 2243 * state, only special requests will be accepted, all others will 2244 * be deferred. Since special requests may also be requeued requests, 2245 * a successful return doesn't guarantee the device will be 2246 * totally quiescent. 2247 * 2248 * Must be called with user context, may sleep. 2249 * 2250 * Returns zero if unsuccessful or an error if not. 2251 */ 2252int 2253scsi_device_quiesce(struct scsi_device *sdev) 2254{ 2255 int err = scsi_device_set_state(sdev, SDEV_QUIESCE); 2256 if (err) 2257 return err; 2258 2259 scsi_run_queue(sdev->request_queue); 2260 while (sdev->device_busy) { 2261 msleep_interruptible(200); 2262 scsi_run_queue(sdev->request_queue); 2263 } 2264 return 0; 2265} 2266EXPORT_SYMBOL(scsi_device_quiesce); 2267 2268/** 2269 * scsi_device_resume - Restart user issued commands to a quiesced device. 2270 * @sdev: scsi device to resume. 2271 * 2272 * Moves the device from quiesced back to running and restarts the 2273 * queues. 2274 * 2275 * Must be called with user context, may sleep. 2276 */ 2277void 2278scsi_device_resume(struct scsi_device *sdev) 2279{ 2280 if(scsi_device_set_state(sdev, SDEV_RUNNING)) 2281 return; 2282 scsi_run_queue(sdev->request_queue); 2283} 2284EXPORT_SYMBOL(scsi_device_resume); 2285 2286static void 2287device_quiesce_fn(struct scsi_device *sdev, void *data) 2288{ 2289 scsi_device_quiesce(sdev); 2290} 2291 2292void 2293scsi_target_quiesce(struct scsi_target *starget) 2294{ 2295 starget_for_each_device(starget, NULL, device_quiesce_fn); 2296} 2297EXPORT_SYMBOL(scsi_target_quiesce); 2298 2299static void 2300device_resume_fn(struct scsi_device *sdev, void *data) 2301{ 2302 scsi_device_resume(sdev); 2303} 2304 2305void 2306scsi_target_resume(struct scsi_target *starget) 2307{ 2308 starget_for_each_device(starget, NULL, device_resume_fn); 2309} 2310EXPORT_SYMBOL(scsi_target_resume); 2311 2312/** 2313 * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state 2314 * @sdev: device to block 2315 * 2316 * Block request made by scsi lld's to temporarily stop all 2317 * scsi commands on the specified device. Called from interrupt 2318 * or normal process context. 2319 * 2320 * Returns zero if successful or error if not 2321 * 2322 * Notes: 2323 * This routine transitions the device to the SDEV_BLOCK state 2324 * (which must be a legal transition). When the device is in this 2325 * state, all commands are deferred until the scsi lld reenables 2326 * the device with scsi_device_unblock or device_block_tmo fires. 2327 * This routine assumes the host_lock is held on entry. 2328 */ 2329int 2330scsi_internal_device_block(struct scsi_device *sdev) 2331{ 2332 struct request_queue *q = sdev->request_queue; 2333 unsigned long flags; 2334 int err = 0; 2335 2336 err = scsi_device_set_state(sdev, SDEV_BLOCK); 2337 if (err) 2338 return err; 2339 2340 /* 2341 * The device has transitioned to SDEV_BLOCK. Stop the 2342 * block layer from calling the midlayer with this device's 2343 * request queue. 2344 */ 2345 spin_lock_irqsave(q->queue_lock, flags); 2346 blk_stop_queue(q); 2347 spin_unlock_irqrestore(q->queue_lock, flags); 2348 2349 return 0; 2350} 2351EXPORT_SYMBOL_GPL(scsi_internal_device_block); 2352 2353/** 2354 * scsi_internal_device_unblock - resume a device after a block request 2355 * @sdev: device to resume 2356 * 2357 * Called by scsi lld's or the midlayer to restart the device queue 2358 * for the previously suspended scsi device. Called from interrupt or 2359 * normal process context. 2360 * 2361 * Returns zero if successful or error if not. 2362 * 2363 * Notes: 2364 * This routine transitions the device to the SDEV_RUNNING state 2365 * (which must be a legal transition) allowing the midlayer to 2366 * goose the queue for this device. This routine assumes the 2367 * host_lock is held upon entry. 2368 */ 2369int 2370scsi_internal_device_unblock(struct scsi_device *sdev) 2371{ 2372 struct request_queue *q = sdev->request_queue; 2373 int err; 2374 unsigned long flags; 2375 2376 /* 2377 * Try to transition the scsi device to SDEV_RUNNING 2378 * and goose the device queue if successful. 2379 */ 2380 err = scsi_device_set_state(sdev, SDEV_RUNNING); 2381 if (err) 2382 return err; 2383 2384 spin_lock_irqsave(q->queue_lock, flags); 2385 blk_start_queue(q); 2386 spin_unlock_irqrestore(q->queue_lock, flags); 2387 2388 return 0; 2389} 2390EXPORT_SYMBOL_GPL(scsi_internal_device_unblock); 2391 2392static void 2393device_block(struct scsi_device *sdev, void *data) 2394{ 2395 scsi_internal_device_block(sdev); 2396} 2397 2398static int 2399target_block(struct device *dev, void *data) 2400{ 2401 if (scsi_is_target_device(dev)) 2402 starget_for_each_device(to_scsi_target(dev), NULL, 2403 device_block); 2404 return 0; 2405} 2406 2407void 2408scsi_target_block(struct device *dev) 2409{ 2410 if (scsi_is_target_device(dev)) 2411 starget_for_each_device(to_scsi_target(dev), NULL, 2412 device_block); 2413 else 2414 device_for_each_child(dev, NULL, target_block); 2415} 2416EXPORT_SYMBOL_GPL(scsi_target_block); 2417 2418static void 2419device_unblock(struct scsi_device *sdev, void *data) 2420{ 2421 scsi_internal_device_unblock(sdev); 2422} 2423 2424static int 2425target_unblock(struct device *dev, void *data) 2426{ 2427 if (scsi_is_target_device(dev)) 2428 starget_for_each_device(to_scsi_target(dev), NULL, 2429 device_unblock); 2430 return 0; 2431} 2432 2433void 2434scsi_target_unblock(struct device *dev) 2435{ 2436 if (scsi_is_target_device(dev)) 2437 starget_for_each_device(to_scsi_target(dev), NULL, 2438 device_unblock); 2439 else 2440 device_for_each_child(dev, NULL, target_unblock); 2441} 2442EXPORT_SYMBOL_GPL(scsi_target_unblock); 2443 2444/** 2445 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt 2446 * @sgl: scatter-gather list 2447 * @sg_count: number of segments in sg 2448 * @offset: offset in bytes into sg, on return offset into the mapped area 2449 * @len: bytes to map, on return number of bytes mapped 2450 * 2451 * Returns virtual address of the start of the mapped page 2452 */ 2453void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count, 2454 size_t *offset, size_t *len) 2455{ 2456 int i; 2457 size_t sg_len = 0, len_complete = 0; 2458 struct scatterlist *sg; 2459 struct page *page; 2460 2461 WARN_ON(!irqs_disabled()); 2462 2463 for_each_sg(sgl, sg, sg_count, i) { 2464 len_complete = sg_len; /* Complete sg-entries */ 2465 sg_len += sg->length; 2466 if (sg_len > *offset) 2467 break; 2468 } 2469 2470 if (unlikely(i == sg_count)) { 2471 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, " 2472 "elements %d\n", 2473 __FUNCTION__, sg_len, *offset, sg_count); 2474 WARN_ON(1); 2475 return NULL; 2476 } 2477 2478 /* Offset starting from the beginning of first page in this sg-entry */ 2479 *offset = *offset - len_complete + sg->offset; 2480 2481 /* Assumption: contiguous pages can be accessed as "page + i" */ 2482 page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT)); 2483 *offset &= ~PAGE_MASK; 2484 2485 /* Bytes in this sg-entry from *offset to the end of the page */ 2486 sg_len = PAGE_SIZE - *offset; 2487 if (*len > sg_len) 2488 *len = sg_len; 2489 2490 return kmap_atomic(page, KM_BIO_SRC_IRQ); 2491} 2492EXPORT_SYMBOL(scsi_kmap_atomic_sg); 2493 2494/** 2495 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg 2496 * @virt: virtual address to be unmapped 2497 */ 2498void scsi_kunmap_atomic_sg(void *virt) 2499{ 2500 kunmap_atomic(virt, KM_BIO_SRC_IRQ); 2501} 2502EXPORT_SYMBOL(scsi_kunmap_atomic_sg); 2503