1/*
   2 * Copyright (C) 1999 Eric Youngdale
   3 * Copyright (C) 2014 Christoph Hellwig
   4 *
   5 *  SCSI queueing library.
   6 *      Initial versions: Eric Youngdale (eric@andante.org).
   7 *                        Based upon conversations with large numbers
   8 *                        of people at Linux Expo.
   9 */
  10
  11#include <linux/bio.h>
  12#include <linux/bitops.h>
  13#include <linux/blkdev.h>
  14#include <linux/completion.h>
  15#include <linux/kernel.h>
  16#include <linux/export.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#include <linux/blk-mq.h>
  23#include <linux/ratelimit.h>
  24#include <asm/unaligned.h>
  25
  26#include <scsi/scsi.h>
  27#include <scsi/scsi_cmnd.h>
  28#include <scsi/scsi_dbg.h>
  29#include <scsi/scsi_device.h>
  30#include <scsi/scsi_driver.h>
  31#include <scsi/scsi_eh.h>
  32#include <scsi/scsi_host.h>
 
  33#include <scsi/scsi_dh.h>
  34
  35#include <trace/events/scsi.h>
  36
 
  37#include "scsi_priv.h"
  38#include "scsi_logging.h"
  39
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  40
  41struct kmem_cache *scsi_sdb_cache;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  42
  43/*
  44 * When to reinvoke queueing after a resource shortage. It's 3 msecs to
  45 * not change behaviour from the previous unplug mechanism, experimentation
  46 * may prove this needs changing.
  47 */
  48#define SCSI_QUEUE_DELAY	3
  49
  50static void
  51scsi_set_blocked(struct scsi_cmnd *cmd, int reason)
  52{
  53	struct Scsi_Host *host = cmd->device->host;
  54	struct scsi_device *device = cmd->device;
  55	struct scsi_target *starget = scsi_target(device);
  56
  57	/*
  58	 * Set the appropriate busy bit for the device/host.
  59	 *
  60	 * If the host/device isn't busy, assume that something actually
  61	 * completed, and that we should be able to queue a command now.
  62	 *
  63	 * Note that the prior mid-layer assumption that any host could
  64	 * always queue at least one command is now broken.  The mid-layer
  65	 * will implement a user specifiable stall (see
  66	 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
  67	 * if a command is requeued with no other commands outstanding
  68	 * either for the device or for the host.
  69	 */
  70	switch (reason) {
  71	case SCSI_MLQUEUE_HOST_BUSY:
  72		atomic_set(&host->host_blocked, host->max_host_blocked);
  73		break;
  74	case SCSI_MLQUEUE_DEVICE_BUSY:
  75	case SCSI_MLQUEUE_EH_RETRY:
  76		atomic_set(&device->device_blocked,
  77			   device->max_device_blocked);
  78		break;
  79	case SCSI_MLQUEUE_TARGET_BUSY:
  80		atomic_set(&starget->target_blocked,
  81			   starget->max_target_blocked);
  82		break;
  83	}
  84}
  85
  86static void scsi_mq_requeue_cmd(struct scsi_cmnd *cmd)
  87{
  88	struct scsi_device *sdev = cmd->device;
  89
 
 
 
 
  90	blk_mq_requeue_request(cmd->request, true);
  91	put_device(&sdev->sdev_gendev);
  92}
  93
  94/**
  95 * __scsi_queue_insert - private queue insertion
  96 * @cmd: The SCSI command being requeued
  97 * @reason:  The reason for the requeue
  98 * @unbusy: Whether the queue should be unbusied
  99 *
 100 * This is a private queue insertion.  The public interface
 101 * scsi_queue_insert() always assumes the queue should be unbusied
 102 * because it's always called before the completion.  This function is
 103 * for a requeue after completion, which should only occur in this
 104 * file.
 105 */
 106static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy)
 107{
 108	struct scsi_device *device = cmd->device;
 109	struct request_queue *q = device->request_queue;
 110	unsigned long flags;
 111
 112	SCSI_LOG_MLQUEUE(1, scmd_printk(KERN_INFO, cmd,
 113		"Inserting command %p into mlqueue\n", cmd));
 114
 115	scsi_set_blocked(cmd, reason);
 116
 117	/*
 118	 * Decrement the counters, since these commands are no longer
 119	 * active on the host/device.
 120	 */
 121	if (unbusy)
 122		scsi_device_unbusy(device);
 123
 124	/*
 125	 * Requeue this command.  It will go before all other commands
 126	 * that are already in the queue. Schedule requeue work under
 127	 * lock such that the kblockd_schedule_work() call happens
 128	 * before blk_cleanup_queue() finishes.
 129	 */
 130	cmd->result = 0;
 131	if (q->mq_ops) {
 132		scsi_mq_requeue_cmd(cmd);
 133		return;
 134	}
 135	spin_lock_irqsave(q->queue_lock, flags);
 136	blk_requeue_request(q, cmd->request);
 137	kblockd_schedule_work(&device->requeue_work);
 138	spin_unlock_irqrestore(q->queue_lock, flags);
 139}
 140
 141/*
 142 * Function:    scsi_queue_insert()
 143 *
 144 * Purpose:     Insert a command in the midlevel queue.
 145 *
 146 * Arguments:   cmd    - command that we are adding to queue.
 147 *              reason - why we are inserting command to queue.
 148 *
 149 * Lock status: Assumed that lock is not held upon entry.
 150 *
 151 * Returns:     Nothing.
 152 *
 153 * Notes:       We do this for one of two cases.  Either the host is busy
 154 *              and it cannot accept any more commands for the time being,
 155 *              or the device returned QUEUE_FULL and can accept no more
 156 *              commands.
 157 * Notes:       This could be called either from an interrupt context or a
 158 *              normal process context.
 159 */
 160void scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
 161{
 162	__scsi_queue_insert(cmd, reason, 1);
 163}
 164
 165static int __scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 166		 int data_direction, void *buffer, unsigned bufflen,
 167		 unsigned char *sense, int timeout, int retries, u64 flags,
 168		 req_flags_t rq_flags, int *resid)
 
 169{
 170	struct request *req;
 171	int write = (data_direction == DMA_TO_DEVICE);
 172	int ret = DRIVER_ERROR << 24;
 173
 174	req = blk_get_request(sdev->request_queue, write, __GFP_RECLAIM);
 
 
 
 175	if (IS_ERR(req))
 176		return ret;
 177	blk_rq_set_block_pc(req);
 178
 179	if (bufflen &&	blk_rq_map_kern(sdev->request_queue, req,
 180					buffer, bufflen, __GFP_RECLAIM))
 181		goto out;
 182
 183	req->cmd_len = COMMAND_SIZE(cmd[0]);
 184	memcpy(req->cmd, cmd, req->cmd_len);
 185	req->sense = sense;
 186	req->sense_len = 0;
 187	req->retries = retries;
 
 
 
 
 188	req->timeout = timeout;
 189	req->cmd_flags |= flags;
 190	req->rq_flags |= rq_flags | RQF_QUIET | RQF_PREEMPT;
 191
 192	/*
 193	 * head injection *required* here otherwise quiesce won't work
 194	 */
 195	blk_execute_rq(req->q, NULL, req, 1);
 196
 197	/*
 198	 * Some devices (USB mass-storage in particular) may transfer
 199	 * garbage data together with a residue indicating that the data
 200	 * is invalid.  Prevent the garbage from being misinterpreted
 201	 * and prevent security leaks by zeroing out the excess data.
 202	 */
 203	if (unlikely(req->resid_len > 0 && req->resid_len <= bufflen))
 204		memset(buffer + (bufflen - req->resid_len), 0, req->resid_len);
 205
 206	if (resid)
 207		*resid = req->resid_len;
 208	ret = req->errors;
 
 
 
 
 209 out:
 210	blk_put_request(req);
 211
 212	return ret;
 213}
 
 214
 215/**
 216 * scsi_execute - insert request and wait for the result
 217 * @sdev:	scsi device
 218 * @cmd:	scsi command
 219 * @data_direction: data direction
 220 * @buffer:	data buffer
 221 * @bufflen:	len of buffer
 222 * @sense:	optional sense buffer
 223 * @timeout:	request timeout in seconds
 224 * @retries:	number of times to retry request
 225 * @flags:	or into request flags;
 226 * @resid:	optional residual length
 227 *
 228 * returns the req->errors value which is the scsi_cmnd result
 229 * field.
 230 */
 231int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
 232		 int data_direction, void *buffer, unsigned bufflen,
 233		 unsigned char *sense, int timeout, int retries, u64 flags,
 234		 int *resid)
 235{
 236	return __scsi_execute(sdev, cmd, data_direction, buffer, bufflen, sense,
 237			timeout, retries, flags, 0, resid);
 238}
 239EXPORT_SYMBOL(scsi_execute);
 240
 241int scsi_execute_req_flags(struct scsi_device *sdev, const unsigned char *cmd,
 242		     int data_direction, void *buffer, unsigned bufflen,
 243		     struct scsi_sense_hdr *sshdr, int timeout, int retries,
 244		     int *resid, u64 flags, req_flags_t rq_flags)
 245{
 246	char *sense = NULL;
 247	int result;
 248	
 249	if (sshdr) {
 250		sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
 251		if (!sense)
 252			return DRIVER_ERROR << 24;
 253	}
 254	result = __scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
 255			      sense, timeout, retries, flags, rq_flags, resid);
 256	if (sshdr)
 257		scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
 258
 259	kfree(sense);
 260	return result;
 261}
 262EXPORT_SYMBOL(scsi_execute_req_flags);
 263
 264/*
 265 * Function:    scsi_init_cmd_errh()
 266 *
 267 * Purpose:     Initialize cmd fields related to error handling.
 268 *
 269 * Arguments:   cmd	- command that is ready to be queued.
 270 *
 271 * Notes:       This function has the job of initializing a number of
 272 *              fields related to error handling.   Typically this will
 273 *              be called once for each command, as required.
 274 */
 275static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
 276{
 277	cmd->serial_number = 0;
 278	scsi_set_resid(cmd, 0);
 279	memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
 280	if (cmd->cmd_len == 0)
 281		cmd->cmd_len = scsi_command_size(cmd->cmnd);
 282}
 283
 284void scsi_device_unbusy(struct scsi_device *sdev)
 285{
 286	struct Scsi_Host *shost = sdev->host;
 287	struct scsi_target *starget = scsi_target(sdev);
 288	unsigned long flags;
 289
 290	atomic_dec(&shost->host_busy);
 
 291	if (starget->can_queue > 0)
 292		atomic_dec(&starget->target_busy);
 293
 294	if (unlikely(scsi_host_in_recovery(shost) &&
 295		     (shost->host_failed || shost->host_eh_scheduled))) {
 296		spin_lock_irqsave(shost->host_lock, flags);
 297		scsi_eh_wakeup(shost);
 298		spin_unlock_irqrestore(shost->host_lock, flags);
 299	}
 300
 301	atomic_dec(&sdev->device_busy);
 302}
 303
 304static void scsi_kick_queue(struct request_queue *q)
 305{
 306	if (q->mq_ops)
 307		blk_mq_start_hw_queues(q);
 308	else
 309		blk_run_queue(q);
 310}
 311
 312/*
 313 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
 314 * and call blk_run_queue for all the scsi_devices on the target -
 315 * including current_sdev first.
 316 *
 317 * Called with *no* scsi locks held.
 318 */
 319static void scsi_single_lun_run(struct scsi_device *current_sdev)
 320{
 321	struct Scsi_Host *shost = current_sdev->host;
 322	struct scsi_device *sdev, *tmp;
 323	struct scsi_target *starget = scsi_target(current_sdev);
 324	unsigned long flags;
 325
 326	spin_lock_irqsave(shost->host_lock, flags);
 327	starget->starget_sdev_user = NULL;
 328	spin_unlock_irqrestore(shost->host_lock, flags);
 329
 330	/*
 331	 * Call blk_run_queue for all LUNs on the target, starting with
 332	 * current_sdev. We race with others (to set starget_sdev_user),
 333	 * but in most cases, we will be first. Ideally, each LU on the
 334	 * target would get some limited time or requests on the target.
 335	 */
 336	scsi_kick_queue(current_sdev->request_queue);
 337
 338	spin_lock_irqsave(shost->host_lock, flags);
 339	if (starget->starget_sdev_user)
 340		goto out;
 341	list_for_each_entry_safe(sdev, tmp, &starget->devices,
 342			same_target_siblings) {
 343		if (sdev == current_sdev)
 344			continue;
 345		if (scsi_device_get(sdev))
 346			continue;
 347
 348		spin_unlock_irqrestore(shost->host_lock, flags);
 349		scsi_kick_queue(sdev->request_queue);
 350		spin_lock_irqsave(shost->host_lock, flags);
 351	
 352		scsi_device_put(sdev);
 353	}
 354 out:
 355	spin_unlock_irqrestore(shost->host_lock, flags);
 356}
 357
 358static inline bool scsi_device_is_busy(struct scsi_device *sdev)
 359{
 360	if (atomic_read(&sdev->device_busy) >= sdev->queue_depth)
 361		return true;
 362	if (atomic_read(&sdev->device_blocked) > 0)
 363		return true;
 364	return false;
 365}
 366
 367static inline bool scsi_target_is_busy(struct scsi_target *starget)
 368{
 369	if (starget->can_queue > 0) {
 370		if (atomic_read(&starget->target_busy) >= starget->can_queue)
 371			return true;
 372		if (atomic_read(&starget->target_blocked) > 0)
 373			return true;
 374	}
 375	return false;
 376}
 377
 378static inline bool scsi_host_is_busy(struct Scsi_Host *shost)
 379{
 380	if (shost->can_queue > 0 &&
 381	    atomic_read(&shost->host_busy) >= shost->can_queue)
 382		return true;
 383	if (atomic_read(&shost->host_blocked) > 0)
 384		return true;
 385	if (shost->host_self_blocked)
 386		return true;
 387	return false;
 388}
 389
 390static void scsi_starved_list_run(struct Scsi_Host *shost)
 391{
 392	LIST_HEAD(starved_list);
 393	struct scsi_device *sdev;
 394	unsigned long flags;
 395
 396	spin_lock_irqsave(shost->host_lock, flags);
 397	list_splice_init(&shost->starved_list, &starved_list);
 398
 399	while (!list_empty(&starved_list)) {
 400		struct request_queue *slq;
 401
 402		/*
 403		 * As long as shost is accepting commands and we have
 404		 * starved queues, call blk_run_queue. scsi_request_fn
 405		 * drops the queue_lock and can add us back to the
 406		 * starved_list.
 407		 *
 408		 * host_lock protects the starved_list and starved_entry.
 409		 * scsi_request_fn must get the host_lock before checking
 410		 * or modifying starved_list or starved_entry.
 411		 */
 412		if (scsi_host_is_busy(shost))
 413			break;
 414
 415		sdev = list_entry(starved_list.next,
 416				  struct scsi_device, starved_entry);
 417		list_del_init(&sdev->starved_entry);
 418		if (scsi_target_is_busy(scsi_target(sdev))) {
 419			list_move_tail(&sdev->starved_entry,
 420				       &shost->starved_list);
 421			continue;
 422		}
 423
 424		/*
 425		 * Once we drop the host lock, a racing scsi_remove_device()
 426		 * call may remove the sdev from the starved list and destroy
 427		 * it and the queue.  Mitigate by taking a reference to the
 428		 * queue and never touching the sdev again after we drop the
 429		 * host lock.  Note: if __scsi_remove_device() invokes
 430		 * blk_cleanup_queue() before the queue is run from this
 431		 * function then blk_run_queue() will return immediately since
 432		 * blk_cleanup_queue() marks the queue with QUEUE_FLAG_DYING.
 433		 */
 434		slq = sdev->request_queue;
 435		if (!blk_get_queue(slq))
 436			continue;
 437		spin_unlock_irqrestore(shost->host_lock, flags);
 438
 439		scsi_kick_queue(slq);
 440		blk_put_queue(slq);
 441
 442		spin_lock_irqsave(shost->host_lock, flags);
 443	}
 444	/* put any unprocessed entries back */
 445	list_splice(&starved_list, &shost->starved_list);
 446	spin_unlock_irqrestore(shost->host_lock, flags);
 447}
 448
 449/*
 450 * Function:   scsi_run_queue()
 451 *
 452 * Purpose:    Select a proper request queue to serve next
 453 *
 454 * Arguments:  q       - last request's queue
 455 *
 456 * Returns:     Nothing
 457 *
 458 * Notes:      The previous command was completely finished, start
 459 *             a new one if possible.
 460 */
 461static void scsi_run_queue(struct request_queue *q)
 462{
 463	struct scsi_device *sdev = q->queuedata;
 464
 465	if (scsi_target(sdev)->single_lun)
 466		scsi_single_lun_run(sdev);
 467	if (!list_empty(&sdev->host->starved_list))
 468		scsi_starved_list_run(sdev->host);
 469
 470	if (q->mq_ops)
 471		blk_mq_start_stopped_hw_queues(q, false);
 472	else
 473		blk_run_queue(q);
 474}
 475
 476void scsi_requeue_run_queue(struct work_struct *work)
 477{
 478	struct scsi_device *sdev;
 479	struct request_queue *q;
 480
 481	sdev = container_of(work, struct scsi_device, requeue_work);
 482	q = sdev->request_queue;
 483	scsi_run_queue(q);
 484}
 485
 486/*
 487 * Function:	scsi_requeue_command()
 488 *
 489 * Purpose:	Handle post-processing of completed commands.
 490 *
 491 * Arguments:	q	- queue to operate on
 492 *		cmd	- command that may need to be requeued.
 493 *
 494 * Returns:	Nothing
 495 *
 496 * Notes:	After command completion, there may be blocks left
 497 *		over which weren't finished by the previous command
 498 *		this can be for a number of reasons - the main one is
 499 *		I/O errors in the middle of the request, in which case
 500 *		we need to request the blocks that come after the bad
 501 *		sector.
 502 * Notes:	Upon return, cmd is a stale pointer.
 503 */
 504static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
 505{
 506	struct scsi_device *sdev = cmd->device;
 507	struct request *req = cmd->request;
 508	unsigned long flags;
 509
 510	spin_lock_irqsave(q->queue_lock, flags);
 511	blk_unprep_request(req);
 512	req->special = NULL;
 513	scsi_put_command(cmd);
 514	blk_requeue_request(q, req);
 515	spin_unlock_irqrestore(q->queue_lock, flags);
 516
 517	scsi_run_queue(q);
 518
 519	put_device(&sdev->sdev_gendev);
 520}
 521
 522void scsi_run_host_queues(struct Scsi_Host *shost)
 523{
 524	struct scsi_device *sdev;
 525
 526	shost_for_each_device(sdev, shost)
 527		scsi_run_queue(sdev->request_queue);
 528}
 529
 530static void scsi_uninit_cmd(struct scsi_cmnd *cmd)
 531{
 532	if (cmd->request->cmd_type == REQ_TYPE_FS) {
 533		struct scsi_driver *drv = scsi_cmd_to_driver(cmd);
 534
 535		if (drv->uninit_command)
 536			drv->uninit_command(cmd);
 537	}
 538}
 539
 540static void scsi_mq_free_sgtables(struct scsi_cmnd *cmd)
 541{
 542	struct scsi_data_buffer *sdb;
 543
 544	if (cmd->sdb.table.nents)
 545		sg_free_table_chained(&cmd->sdb.table, true);
 546	if (cmd->request->next_rq) {
 547		sdb = cmd->request->next_rq->special;
 548		if (sdb)
 549			sg_free_table_chained(&sdb->table, true);
 550	}
 551	if (scsi_prot_sg_count(cmd))
 552		sg_free_table_chained(&cmd->prot_sdb->table, true);
 
 553}
 
 554
 555static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd)
 556{
 557	struct scsi_device *sdev = cmd->device;
 558	struct Scsi_Host *shost = sdev->host;
 559	unsigned long flags;
 560
 561	scsi_mq_free_sgtables(cmd);
 562	scsi_uninit_cmd(cmd);
 563
 564	if (shost->use_cmd_list) {
 565		BUG_ON(list_empty(&cmd->list));
 566		spin_lock_irqsave(&sdev->list_lock, flags);
 567		list_del_init(&cmd->list);
 568		spin_unlock_irqrestore(&sdev->list_lock, flags);
 569	}
 570}
 571
 572/*
 573 * Function:    scsi_release_buffers()
 574 *
 575 * Purpose:     Free resources allocate for a scsi_command.
 576 *
 577 * Arguments:   cmd	- command that we are bailing.
 578 *
 579 * Lock status: Assumed that no lock is held upon entry.
 580 *
 581 * Returns:     Nothing
 582 *
 583 * Notes:       In the event that an upper level driver rejects a
 584 *		command, we must release resources allocated during
 585 *		the __init_io() function.  Primarily this would involve
 586 *		the scatter-gather table.
 587 */
 588static void scsi_release_buffers(struct scsi_cmnd *cmd)
 589{
 590	if (cmd->sdb.table.nents)
 591		sg_free_table_chained(&cmd->sdb.table, false);
 592
 593	memset(&cmd->sdb, 0, sizeof(cmd->sdb));
 594
 595	if (scsi_prot_sg_count(cmd))
 596		sg_free_table_chained(&cmd->prot_sdb->table, false);
 597}
 598
 599static void scsi_release_bidi_buffers(struct scsi_cmnd *cmd)
 600{
 601	struct scsi_data_buffer *bidi_sdb = cmd->request->next_rq->special;
 602
 603	sg_free_table_chained(&bidi_sdb->table, false);
 604	kmem_cache_free(scsi_sdb_cache, bidi_sdb);
 605	cmd->request->next_rq->special = NULL;
 
 
 
 
 
 
 
 
 606}
 607
 608static bool scsi_end_request(struct request *req, int error,
 609		unsigned int bytes, unsigned int bidi_bytes)
 
 610{
 611	struct scsi_cmnd *cmd = req->special;
 612	struct scsi_device *sdev = cmd->device;
 613	struct request_queue *q = sdev->request_queue;
 614
 615	if (blk_update_request(req, error, bytes))
 616		return true;
 617
 618	/* Bidi request must be completed as a whole */
 619	if (unlikely(bidi_bytes) &&
 620	    blk_update_request(req->next_rq, error, bidi_bytes))
 621		return true;
 622
 623	if (blk_queue_add_random(q))
 624		add_disk_randomness(req->rq_disk);
 625
 626	if (req->mq_ctx) {
 627		/*
 628		 * In the MQ case the command gets freed by __blk_mq_end_request,
 629		 * so we have to do all cleanup that depends on it earlier.
 630		 *
 631		 * We also can't kick the queues from irq context, so we
 632		 * will have to defer it to a workqueue.
 633		 */
 634		scsi_mq_uninit_cmd(cmd);
 635
 636		__blk_mq_end_request(req, error);
 637
 638		if (scsi_target(sdev)->single_lun ||
 639		    !list_empty(&sdev->host->starved_list))
 640			kblockd_schedule_work(&sdev->requeue_work);
 641		else
 642			blk_mq_start_stopped_hw_queues(q, true);
 643	} else {
 644		unsigned long flags;
 645
 646		if (bidi_bytes)
 647			scsi_release_bidi_buffers(cmd);
 
 
 
 
 
 
 648
 649		spin_lock_irqsave(q->queue_lock, flags);
 650		blk_finish_request(req, error);
 651		spin_unlock_irqrestore(q->queue_lock, flags);
 
 
 652
 653		scsi_release_buffers(cmd);
 654
 655		scsi_put_command(cmd);
 656		scsi_run_queue(q);
 657	}
 658
 659	put_device(&sdev->sdev_gendev);
 660	return false;
 661}
 662
 663/**
 664 * __scsi_error_from_host_byte - translate SCSI error code into errno
 665 * @cmd:	SCSI command (unused)
 666 * @result:	scsi error code
 667 *
 668 * Translate SCSI error code into standard UNIX errno.
 669 * Return values:
 670 * -ENOLINK	temporary transport failure
 671 * -EREMOTEIO	permanent target failure, do not retry
 672 * -EBADE	permanent nexus failure, retry on other path
 673 * -ENOSPC	No write space available
 674 * -ENODATA	Medium error
 675 * -EIO		unspecified I/O error
 676 */
 677static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result)
 678{
 679	int error = 0;
 680
 681	switch(host_byte(result)) {
 
 
 682	case DID_TRANSPORT_FAILFAST:
 683		error = -ENOLINK;
 684		break;
 685	case DID_TARGET_FAILURE:
 686		set_host_byte(cmd, DID_OK);
 687		error = -EREMOTEIO;
 688		break;
 689	case DID_NEXUS_FAILURE:
 690		set_host_byte(cmd, DID_OK);
 691		error = -EBADE;
 692		break;
 693	case DID_ALLOC_FAILURE:
 694		set_host_byte(cmd, DID_OK);
 695		error = -ENOSPC;
 696		break;
 697	case DID_MEDIUM_ERROR:
 698		set_host_byte(cmd, DID_OK);
 699		error = -ENODATA;
 700		break;
 701	default:
 702		error = -EIO;
 703		break;
 704	}
 
 705
 706	return error;
 
 
 
 
 
 707}
 708
 709/*
 710 * Function:    scsi_io_completion()
 711 *
 712 * Purpose:     Completion processing for block device I/O requests.
 713 *
 714 * Arguments:   cmd   - command that is finished.
 715 *
 716 * Lock status: Assumed that no lock is held upon entry.
 717 *
 718 * Returns:     Nothing
 719 *
 720 * Notes:       We will finish off the specified number of sectors.  If we
 721 *		are done, the command block will be released and the queue
 722 *		function will be goosed.  If we are not done then we have to
 723 *		figure out what to do next:
 724 *
 725 *		a) We can call scsi_requeue_command().  The request
 726 *		   will be unprepared and put back on the queue.  Then
 727 *		   a new command will be created for it.  This should
 728 *		   be used if we made forward progress, or if we want
 729 *		   to switch from READ(10) to READ(6) for example.
 730 *
 731 *		b) We can call __scsi_queue_insert().  The request will
 732 *		   be put back on the queue and retried using the same
 733 *		   command as before, possibly after a delay.
 734 *
 735 *		c) We can call scsi_end_request() with -EIO to fail
 736 *		   the remainder of the request.
 737 */
 738void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 739{
 740	int result = cmd->result;
 741	struct request_queue *q = cmd->device->request_queue;
 742	struct request *req = cmd->request;
 743	int error = 0;
 744	struct scsi_sense_hdr sshdr;
 745	bool sense_valid = false;
 746	int sense_deferred = 0, level = 0;
 747	enum {ACTION_FAIL, ACTION_REPREP, ACTION_RETRY,
 748	      ACTION_DELAYED_RETRY} action;
 749	unsigned long wait_for = (cmd->allowed + 1) * req->timeout;
 750
 751	if (result) {
 752		sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
 753		if (sense_valid)
 754			sense_deferred = scsi_sense_is_deferred(&sshdr);
 755	}
 756
 757	if (req->cmd_type == REQ_TYPE_BLOCK_PC) { /* SG_IO ioctl from block level */
 758		if (result) {
 759			if (sense_valid && req->sense) {
 760				/*
 761				 * SG_IO wants current and deferred errors
 762				 */
 763				int len = 8 + cmd->sense_buffer[7];
 764
 765				if (len > SCSI_SENSE_BUFFERSIZE)
 766					len = SCSI_SENSE_BUFFERSIZE;
 767				memcpy(req->sense, cmd->sense_buffer,  len);
 768				req->sense_len = len;
 769			}
 770			if (!sense_deferred)
 771				error = __scsi_error_from_host_byte(cmd, result);
 772		}
 773		/*
 774		 * __scsi_error_from_host_byte may have reset the host_byte
 775		 */
 776		req->errors = cmd->result;
 777
 778		req->resid_len = scsi_get_resid(cmd);
 779
 780		if (scsi_bidi_cmnd(cmd)) {
 781			/*
 782			 * Bidi commands Must be complete as a whole,
 783			 * both sides at once.
 784			 */
 785			req->next_rq->resid_len = scsi_in(cmd)->resid;
 786			if (scsi_end_request(req, 0, blk_rq_bytes(req),
 787					blk_rq_bytes(req->next_rq)))
 788				BUG();
 789			return;
 790		}
 791	} else if (blk_rq_bytes(req) == 0 && result && !sense_deferred) {
 792		/*
 793		 * Certain non BLOCK_PC requests are commands that don't
 794		 * actually transfer anything (FLUSH), so cannot use
 795		 * good_bytes != blk_rq_bytes(req) as the signal for an error.
 796		 * This sets the error explicitly for the problem case.
 797		 */
 798		error = __scsi_error_from_host_byte(cmd, result);
 799	}
 800
 801	/* no bidi support for !REQ_TYPE_BLOCK_PC yet */
 802	BUG_ON(blk_bidi_rq(req));
 803
 804	/*
 805	 * Next deal with any sectors which we were able to correctly
 806	 * handle.
 807	 */
 808	SCSI_LOG_HLCOMPLETE(1, scmd_printk(KERN_INFO, cmd,
 809		"%u sectors total, %d bytes done.\n",
 810		blk_rq_sectors(req), good_bytes));
 811
 812	/*
 813	 * Recovered errors need reporting, but they're always treated
 814	 * as success, so fiddle the result code here.  For BLOCK_PC
 815	 * we already took a copy of the original into rq->errors which
 816	 * is what gets returned to the user
 817	 */
 818	if (sense_valid && (sshdr.sense_key == RECOVERED_ERROR)) {
 819		/* if ATA PASS-THROUGH INFORMATION AVAILABLE skip
 820		 * print since caller wants ATA registers. Only occurs on
 821		 * SCSI ATA PASS_THROUGH commands when CK_COND=1
 822		 */
 823		if ((sshdr.asc == 0x0) && (sshdr.ascq == 0x1d))
 824			;
 825		else if (!(req->rq_flags & RQF_QUIET))
 826			scsi_print_sense(cmd);
 827		result = 0;
 828		/* BLOCK_PC may have set error */
 829		error = 0;
 830	}
 831
 832	/*
 833	 * special case: failed zero length commands always need to
 834	 * drop down into the retry code. Otherwise, if we finished
 835	 * all bytes in the request we are done now.
 836	 */
 837	if (!(blk_rq_bytes(req) == 0 && error) &&
 838	    !scsi_end_request(req, error, good_bytes, 0))
 839		return;
 840
 841	/*
 842	 * Kill remainder if no retrys.
 843	 */
 844	if (error && scsi_noretry_cmd(cmd)) {
 845		if (scsi_end_request(req, error, blk_rq_bytes(req), 0))
 846			BUG();
 847		return;
 848	}
 
 
 849
 850	/*
 851	 * If there had been no error, but we have leftover bytes in the
 852	 * requeues just queue the command up again.
 853	 */
 854	if (result == 0)
 855		goto requeue;
 
 
 
 
 
 
 
 
 
 
 856
 857	error = __scsi_error_from_host_byte(cmd, result);
 858
 859	if (host_byte(result) == DID_RESET) {
 860		/* Third party bus reset or reset for error recovery
 861		 * reasons.  Just retry the command and see what
 862		 * happens.
 863		 */
 864		action = ACTION_RETRY;
 865	} else if (sense_valid && !sense_deferred) {
 866		switch (sshdr.sense_key) {
 867		case UNIT_ATTENTION:
 868			if (cmd->device->removable) {
 869				/* Detected disc change.  Set a bit
 870				 * and quietly refuse further access.
 871				 */
 872				cmd->device->changed = 1;
 873				action = ACTION_FAIL;
 874			} else {
 875				/* Must have been a power glitch, or a
 876				 * bus reset.  Could not have been a
 877				 * media change, so we just retry the
 878				 * command and see what happens.
 879				 */
 880				action = ACTION_RETRY;
 881			}
 882			break;
 883		case ILLEGAL_REQUEST:
 884			/* If we had an ILLEGAL REQUEST returned, then
 885			 * we may have performed an unsupported
 886			 * command.  The only thing this should be
 887			 * would be a ten byte read where only a six
 888			 * byte read was supported.  Also, on a system
 889			 * where READ CAPACITY failed, we may have
 890			 * read past the end of the disk.
 891			 */
 892			if ((cmd->device->use_10_for_rw &&
 893			    sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
 894			    (cmd->cmnd[0] == READ_10 ||
 895			     cmd->cmnd[0] == WRITE_10)) {
 896				/* This will issue a new 6-byte command. */
 897				cmd->device->use_10_for_rw = 0;
 898				action = ACTION_REPREP;
 899			} else if (sshdr.asc == 0x10) /* DIX */ {
 900				action = ACTION_FAIL;
 901				error = -EILSEQ;
 902			/* INVALID COMMAND OPCODE or INVALID FIELD IN CDB */
 903			} else if (sshdr.asc == 0x20 || sshdr.asc == 0x24) {
 904				action = ACTION_FAIL;
 905				error = -EREMOTEIO;
 906			} else
 907				action = ACTION_FAIL;
 908			break;
 909		case ABORTED_COMMAND:
 910			action = ACTION_FAIL;
 911			if (sshdr.asc == 0x10) /* DIF */
 912				error = -EILSEQ;
 913			break;
 914		case NOT_READY:
 915			/* If the device is in the process of becoming
 916			 * ready, or has a temporary blockage, retry.
 917			 */
 918			if (sshdr.asc == 0x04) {
 919				switch (sshdr.ascq) {
 920				case 0x01: /* becoming ready */
 921				case 0x04: /* format in progress */
 922				case 0x05: /* rebuild in progress */
 923				case 0x06: /* recalculation in progress */
 924				case 0x07: /* operation in progress */
 925				case 0x08: /* Long write in progress */
 926				case 0x09: /* self test in progress */
 
 927				case 0x14: /* space allocation in progress */
 
 
 
 
 928					action = ACTION_DELAYED_RETRY;
 929					break;
 
 
 
 930				default:
 931					action = ACTION_FAIL;
 932					break;
 933				}
 934			} else
 935				action = ACTION_FAIL;
 936			break;
 937		case VOLUME_OVERFLOW:
 938			/* See SSC3rXX or current. */
 939			action = ACTION_FAIL;
 940			break;
 
 
 
 
 
 
 
 
 
 941		default:
 942			action = ACTION_FAIL;
 943			break;
 944		}
 945	} else
 946		action = ACTION_FAIL;
 947
 948	if (action != ACTION_FAIL &&
 949	    time_before(cmd->jiffies_at_alloc + wait_for, jiffies))
 950		action = ACTION_FAIL;
 951
 952	switch (action) {
 953	case ACTION_FAIL:
 954		/* Give up and fail the remainder of the request */
 955		if (!(req->rq_flags & RQF_QUIET)) {
 956			static DEFINE_RATELIMIT_STATE(_rs,
 957					DEFAULT_RATELIMIT_INTERVAL,
 958					DEFAULT_RATELIMIT_BURST);
 959
 960			if (unlikely(scsi_logging_level))
 961				level = SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
 962						       SCSI_LOG_MLCOMPLETE_BITS);
 
 963
 964			/*
 965			 * if logging is enabled the failure will be printed
 966			 * in scsi_log_completion(), so avoid duplicate messages
 967			 */
 968			if (!level && __ratelimit(&_rs)) {
 969				scsi_print_result(cmd, NULL, FAILED);
 970				if (driver_byte(result) & DRIVER_SENSE)
 971					scsi_print_sense(cmd);
 972				scsi_print_command(cmd);
 973			}
 974		}
 975		if (!scsi_end_request(req, error, blk_rq_err_bytes(req), 0))
 976			return;
 977		/*FALLTHRU*/
 978	case ACTION_REPREP:
 979	requeue:
 980		/* Unprep the request and put it back at the head of the queue.
 981		 * A new command will be prepared and issued.
 982		 */
 983		if (q->mq_ops) {
 984			cmd->request->rq_flags &= ~RQF_DONTPREP;
 985			scsi_mq_uninit_cmd(cmd);
 986			scsi_mq_requeue_cmd(cmd);
 987		} else {
 988			scsi_release_buffers(cmd);
 989			scsi_requeue_command(q, cmd);
 990		}
 991		break;
 992	case ACTION_RETRY:
 993		/* Retry the same command immediately */
 994		__scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, 0);
 995		break;
 996	case ACTION_DELAYED_RETRY:
 997		/* Retry the same command after a delay */
 998		__scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0);
 999		break;
1000	}
1001}
1002
1003static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb)
 
 
 
 
 
 
1004{
1005	int count;
 
 
 
 
 
 
 
1006
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1007	/*
1008	 * If sg table allocation fails, requeue request later.
 
 
 
1009	 */
1010	if (unlikely(sg_alloc_table_chained(&sdb->table,
1011			blk_rq_nr_phys_segments(req), sdb->table.sgl)))
1012		return BLKPREP_DEFER;
1013
1014	/* 
1015	 * Next, walk the list, and fill in the addresses and sizes of
1016	 * each segment.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1017	 */
1018	count = blk_rq_map_sg(req->q, req, sdb->table.sgl);
1019	BUG_ON(count > sdb->table.nents);
1020	sdb->table.nents = count;
1021	sdb->length = blk_rq_payload_bytes(req);
1022	return BLKPREP_OK;
1023}
1024
1025/*
1026 * Function:    scsi_init_io()
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1027 *
1028 * Purpose:     SCSI I/O initialize function.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1029 *
1030 * Arguments:   cmd   - Command descriptor we wish to initialize
 
1031 *
1032 * Returns:     0 on success
1033 *		BLKPREP_DEFER if the failure is retryable
1034 *		BLKPREP_KILL if the failure is fatal
 
1035 */
1036int scsi_init_io(struct scsi_cmnd *cmd)
1037{
1038	struct scsi_device *sdev = cmd->device;
1039	struct request *rq = cmd->request;
1040	bool is_mq = (rq->mq_ctx != NULL);
1041	int error;
 
 
 
1042
1043	if (WARN_ON_ONCE(!blk_rq_nr_phys_segments(rq)))
1044		return -EINVAL;
1045
1046	error = scsi_init_sgtable(rq, &cmd->sdb);
1047	if (error)
1048		goto err_exit;
1049
1050	if (blk_bidi_rq(rq)) {
1051		if (!rq->q->mq_ops) {
1052			struct scsi_data_buffer *bidi_sdb =
1053				kmem_cache_zalloc(scsi_sdb_cache, GFP_ATOMIC);
1054			if (!bidi_sdb) {
1055				error = BLKPREP_DEFER;
1056				goto err_exit;
1057			}
1058
1059			rq->next_rq->special = bidi_sdb;
1060		}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1061
1062		error = scsi_init_sgtable(rq->next_rq, rq->next_rq->special);
1063		if (error)
1064			goto err_exit;
 
 
 
 
 
1065	}
1066
 
 
 
 
1067	if (blk_integrity_rq(rq)) {
1068		struct scsi_data_buffer *prot_sdb = cmd->prot_sdb;
1069		int ivecs, count;
1070
1071		if (prot_sdb == NULL) {
1072			/*
1073			 * This can happen if someone (e.g. multipath)
1074			 * queues a command to a device on an adapter
1075			 * that does not support DIX.
1076			 */
1077			WARN_ON_ONCE(1);
1078			error = BLKPREP_KILL;
1079			goto err_exit;
1080		}
1081
1082		ivecs = blk_rq_count_integrity_sg(rq->q, rq->bio);
1083
1084		if (sg_alloc_table_chained(&prot_sdb->table, ivecs,
1085				prot_sdb->table.sgl)) {
1086			error = BLKPREP_DEFER;
1087			goto err_exit;
 
1088		}
1089
1090		count = blk_rq_map_integrity_sg(rq->q, rq->bio,
1091						prot_sdb->table.sgl);
1092		BUG_ON(unlikely(count > ivecs));
1093		BUG_ON(unlikely(count > queue_max_integrity_segments(rq->q)));
1094
1095		cmd->prot_sdb = prot_sdb;
1096		cmd->prot_sdb->table.nents = count;
1097	}
1098
1099	return BLKPREP_OK;
1100err_exit:
1101	if (is_mq) {
1102		scsi_mq_free_sgtables(cmd);
1103	} else {
1104		scsi_release_buffers(cmd);
1105		cmd->request->special = NULL;
1106		scsi_put_command(cmd);
1107		put_device(&sdev->sdev_gendev);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1108	}
1109	return error;
1110}
1111EXPORT_SYMBOL(scsi_init_io);
1112
1113static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
1114		struct request *req)
1115{
1116	struct scsi_cmnd *cmd;
 
 
 
 
 
 
 
1117
1118	if (!req->special) {
1119		/* Bail if we can't get a reference to the device */
1120		if (!get_device(&sdev->sdev_gendev))
1121			return NULL;
1122
1123		cmd = scsi_get_command(sdev, GFP_ATOMIC);
1124		if (unlikely(!cmd)) {
1125			put_device(&sdev->sdev_gendev);
1126			return NULL;
1127		}
1128		req->special = cmd;
1129	} else {
1130		cmd = req->special;
1131	}
1132
1133	/* pull a tag out of the request if we have one */
1134	cmd->tag = req->tag;
1135	cmd->request = req;
 
 
 
 
 
 
 
 
 
1136
1137	cmd->cmnd = req->cmd;
1138	cmd->prot_op = SCSI_PROT_NORMAL;
 
 
 
 
 
 
 
 
1139
1140	return cmd;
1141}
1142
1143static int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
 
1144{
1145	struct scsi_cmnd *cmd = req->special;
1146
1147	/*
1148	 * BLOCK_PC requests may transfer data, in which case they must
1149	 * a bio attached to them.  Or they might contain a SCSI command
1150	 * that does not transfer data, in which case they may optionally
1151	 * submit a request without an attached bio.
1152	 */
1153	if (req->bio) {
1154		int ret = scsi_init_io(cmd);
1155		if (unlikely(ret))
1156			return ret;
1157	} else {
1158		BUG_ON(blk_rq_bytes(req));
1159
1160		memset(&cmd->sdb, 0, sizeof(cmd->sdb));
1161	}
1162
1163	cmd->cmd_len = req->cmd_len;
 
 
 
1164	cmd->transfersize = blk_rq_bytes(req);
1165	cmd->allowed = req->retries;
1166	return BLKPREP_OK;
1167}
1168
1169/*
1170 * Setup a REQ_TYPE_FS command.  These are simple request from filesystems
1171 * that still need to be translated to SCSI CDBs from the ULD.
1172 */
1173static int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
1174{
1175	struct scsi_cmnd *cmd = req->special;
1176
1177	if (unlikely(sdev->handler && sdev->handler->prep_fn)) {
1178		int ret = sdev->handler->prep_fn(sdev, req);
1179		if (ret != BLKPREP_OK)
1180			return ret;
1181	}
1182
1183	memset(cmd->cmnd, 0, BLK_MAX_CDB);
1184	return scsi_cmd_to_driver(cmd)->init_command(cmd);
1185}
1186
1187static int scsi_setup_cmnd(struct scsi_device *sdev, struct request *req)
1188{
1189	struct scsi_cmnd *cmd = req->special;
1190
1191	if (!blk_rq_bytes(req))
1192		cmd->sc_data_direction = DMA_NONE;
1193	else if (rq_data_dir(req) == WRITE)
1194		cmd->sc_data_direction = DMA_TO_DEVICE;
1195	else
1196		cmd->sc_data_direction = DMA_FROM_DEVICE;
1197
1198	switch (req->cmd_type) {
1199	case REQ_TYPE_FS:
1200		return scsi_setup_fs_cmnd(sdev, req);
1201	case REQ_TYPE_BLOCK_PC:
1202		return scsi_setup_blk_pc_cmnd(sdev, req);
1203	default:
1204		return BLKPREP_KILL;
1205	}
1206}
1207
1208static int
1209scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
1210{
1211	int ret = BLKPREP_OK;
1212
1213	/*
1214	 * If the device is not in running state we will reject some
1215	 * or all commands.
1216	 */
1217	if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1218		switch (sdev->sdev_state) {
1219		case SDEV_OFFLINE:
1220		case SDEV_TRANSPORT_OFFLINE:
1221			/*
1222			 * If the device is offline we refuse to process any
1223			 * commands.  The device must be brought online
1224			 * before trying any recovery commands.
1225			 */
1226			sdev_printk(KERN_ERR, sdev,
1227				    "rejecting I/O to offline device\n");
1228			ret = BLKPREP_KILL;
1229			break;
1230		case SDEV_DEL:
1231			/*
1232			 * If the device is fully deleted, we refuse to
1233			 * process any commands as well.
1234			 */
1235			sdev_printk(KERN_ERR, sdev,
1236				    "rejecting I/O to dead device\n");
1237			ret = BLKPREP_KILL;
1238			break;
1239		case SDEV_BLOCK:
1240		case SDEV_CREATED_BLOCK:
1241			ret = BLKPREP_DEFER;
1242			break;
1243		case SDEV_QUIESCE:
1244			/*
1245			 * If the devices is blocked we defer normal commands.
1246			 */
1247			if (!(req->rq_flags & RQF_PREEMPT))
1248				ret = BLKPREP_DEFER;
1249			break;
1250		default:
1251			/*
1252			 * For any other not fully online state we only allow
1253			 * special commands.  In particular any user initiated
1254			 * command is not allowed.
1255			 */
1256			if (!(req->rq_flags & RQF_PREEMPT))
1257				ret = BLKPREP_KILL;
1258			break;
1259		}
1260	}
1261	return ret;
1262}
1263
1264static int
1265scsi_prep_return(struct request_queue *q, struct request *req, int ret)
1266{
1267	struct scsi_device *sdev = q->queuedata;
1268
1269	switch (ret) {
1270	case BLKPREP_KILL:
1271	case BLKPREP_INVALID:
1272		req->errors = DID_NO_CONNECT << 16;
1273		/* release the command and kill it */
1274		if (req->special) {
1275			struct scsi_cmnd *cmd = req->special;
1276			scsi_release_buffers(cmd);
1277			scsi_put_command(cmd);
1278			put_device(&sdev->sdev_gendev);
1279			req->special = NULL;
1280		}
1281		break;
1282	case BLKPREP_DEFER:
1283		/*
1284		 * If we defer, the blk_peek_request() returns NULL, but the
1285		 * queue must be restarted, so we schedule a callback to happen
1286		 * shortly.
1287		 */
1288		if (atomic_read(&sdev->device_busy) == 0)
1289			blk_delay_queue(q, SCSI_QUEUE_DELAY);
1290		break;
 
 
 
 
 
 
 
 
 
 
 
1291	default:
1292		req->rq_flags |= RQF_DONTPREP;
1293	}
1294
1295	return ret;
1296}
1297
1298static int scsi_prep_fn(struct request_queue *q, struct request *req)
1299{
1300	struct scsi_device *sdev = q->queuedata;
1301	struct scsi_cmnd *cmd;
1302	int ret;
1303
1304	ret = scsi_prep_state_check(sdev, req);
1305	if (ret != BLKPREP_OK)
1306		goto out;
1307
1308	cmd = scsi_get_cmd_from_req(sdev, req);
1309	if (unlikely(!cmd)) {
1310		ret = BLKPREP_DEFER;
1311		goto out;
1312	}
1313
1314	ret = scsi_setup_cmnd(sdev, req);
1315out:
1316	return scsi_prep_return(q, req, ret);
1317}
1318
1319static void scsi_unprep_fn(struct request_queue *q, struct request *req)
1320{
1321	scsi_uninit_cmd(req->special);
1322}
1323
1324/*
1325 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1326 * return 0.
1327 *
1328 * Called with the queue_lock held.
1329 */
1330static inline int scsi_dev_queue_ready(struct request_queue *q,
1331				  struct scsi_device *sdev)
1332{
1333	unsigned int busy;
1334
1335	busy = atomic_inc_return(&sdev->device_busy) - 1;
1336	if (atomic_read(&sdev->device_blocked)) {
1337		if (busy)
 
 
 
1338			goto out_dec;
1339
1340		/*
1341		 * unblock after device_blocked iterates to zero
1342		 */
1343		if (atomic_dec_return(&sdev->device_blocked) > 0) {
1344			/*
1345			 * For the MQ case we take care of this in the caller.
1346			 */
1347			if (!q->mq_ops)
1348				blk_delay_queue(q, SCSI_QUEUE_DELAY);
1349			goto out_dec;
1350		}
1351		SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev,
1352				   "unblocking device at zero depth\n"));
1353	}
1354
1355	if (busy >= sdev->queue_depth)
1356		goto out_dec;
1357
1358	return 1;
1359out_dec:
1360	atomic_dec(&sdev->device_busy);
1361	return 0;
 
 
1362}
1363
1364/*
1365 * scsi_target_queue_ready: checks if there we can send commands to target
1366 * @sdev: scsi device on starget to check.
1367 */
1368static inline int scsi_target_queue_ready(struct Scsi_Host *shost,
1369					   struct scsi_device *sdev)
1370{
1371	struct scsi_target *starget = scsi_target(sdev);
1372	unsigned int busy;
1373
1374	if (starget->single_lun) {
1375		spin_lock_irq(shost->host_lock);
1376		if (starget->starget_sdev_user &&
1377		    starget->starget_sdev_user != sdev) {
1378			spin_unlock_irq(shost->host_lock);
1379			return 0;
1380		}
1381		starget->starget_sdev_user = sdev;
1382		spin_unlock_irq(shost->host_lock);
1383	}
1384
1385	if (starget->can_queue <= 0)
1386		return 1;
1387
1388	busy = atomic_inc_return(&starget->target_busy) - 1;
1389	if (atomic_read(&starget->target_blocked) > 0) {
1390		if (busy)
1391			goto starved;
1392
1393		/*
1394		 * unblock after target_blocked iterates to zero
1395		 */
1396		if (atomic_dec_return(&starget->target_blocked) > 0)
1397			goto out_dec;
1398
1399		SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget,
1400				 "unblocking target at zero depth\n"));
1401	}
1402
1403	if (busy >= starget->can_queue)
1404		goto starved;
1405
1406	return 1;
1407
1408starved:
1409	spin_lock_irq(shost->host_lock);
1410	list_move_tail(&sdev->starved_entry, &shost->starved_list);
1411	spin_unlock_irq(shost->host_lock);
1412out_dec:
1413	if (starget->can_queue > 0)
1414		atomic_dec(&starget->target_busy);
1415	return 0;
1416}
1417
1418/*
1419 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1420 * return 0. We must end up running the queue again whenever 0 is
1421 * returned, else IO can hang.
1422 */
1423static inline int scsi_host_queue_ready(struct request_queue *q,
1424				   struct Scsi_Host *shost,
1425				   struct scsi_device *sdev)
 
1426{
1427	unsigned int busy;
1428
1429	if (scsi_host_in_recovery(shost))
1430		return 0;
1431
1432	busy = atomic_inc_return(&shost->host_busy) - 1;
1433	if (atomic_read(&shost->host_blocked) > 0) {
1434		if (busy)
1435			goto starved;
1436
1437		/*
1438		 * unblock after host_blocked iterates to zero
1439		 */
1440		if (atomic_dec_return(&shost->host_blocked) > 0)
1441			goto out_dec;
1442
1443		SCSI_LOG_MLQUEUE(3,
1444			shost_printk(KERN_INFO, shost,
1445				     "unblocking host at zero depth\n"));
1446	}
1447
1448	if (shost->can_queue > 0 && busy >= shost->can_queue)
1449		goto starved;
1450	if (shost->host_self_blocked)
1451		goto starved;
1452
1453	/* We're OK to process the command, so we can't be starved */
1454	if (!list_empty(&sdev->starved_entry)) {
1455		spin_lock_irq(shost->host_lock);
1456		if (!list_empty(&sdev->starved_entry))
1457			list_del_init(&sdev->starved_entry);
1458		spin_unlock_irq(shost->host_lock);
1459	}
1460
 
 
1461	return 1;
1462
1463starved:
1464	spin_lock_irq(shost->host_lock);
1465	if (list_empty(&sdev->starved_entry))
1466		list_add_tail(&sdev->starved_entry, &shost->starved_list);
1467	spin_unlock_irq(shost->host_lock);
1468out_dec:
1469	atomic_dec(&shost->host_busy);
1470	return 0;
1471}
1472
1473/*
1474 * Busy state exporting function for request stacking drivers.
1475 *
1476 * For efficiency, no lock is taken to check the busy state of
1477 * shost/starget/sdev, since the returned value is not guaranteed and
1478 * may be changed after request stacking drivers call the function,
1479 * regardless of taking lock or not.
1480 *
1481 * When scsi can't dispatch I/Os anymore and needs to kill I/Os scsi
1482 * needs to return 'not busy'. Otherwise, request stacking drivers
1483 * may hold requests forever.
1484 */
1485static int scsi_lld_busy(struct request_queue *q)
1486{
1487	struct scsi_device *sdev = q->queuedata;
1488	struct Scsi_Host *shost;
1489
1490	if (blk_queue_dying(q))
1491		return 0;
1492
1493	shost = sdev->host;
1494
1495	/*
1496	 * Ignore host/starget busy state.
1497	 * Since block layer does not have a concept of fairness across
1498	 * multiple queues, congestion of host/starget needs to be handled
1499	 * in SCSI layer.
1500	 */
1501	if (scsi_host_in_recovery(shost) || scsi_device_is_busy(sdev))
1502		return 1;
1503
1504	return 0;
1505}
1506
1507/*
1508 * Kill a request for a dead device
 
1509 */
1510static void scsi_kill_request(struct request *req, struct request_queue *q)
1511{
1512	struct scsi_cmnd *cmd = req->special;
1513	struct scsi_device *sdev;
1514	struct scsi_target *starget;
1515	struct Scsi_Host *shost;
1516
1517	blk_start_request(req);
1518
1519	scmd_printk(KERN_INFO, cmd, "killing request\n");
1520
1521	sdev = cmd->device;
1522	starget = scsi_target(sdev);
1523	shost = sdev->host;
1524	scsi_init_cmd_errh(cmd);
1525	cmd->result = DID_NO_CONNECT << 16;
1526	atomic_inc(&cmd->device->iorequest_cnt);
1527
1528	/*
1529	 * SCSI request completion path will do scsi_device_unbusy(),
1530	 * bump busy counts.  To bump the counters, we need to dance
1531	 * with the locks as normal issue path does.
1532	 */
1533	atomic_inc(&sdev->device_busy);
1534	atomic_inc(&shost->host_busy);
1535	if (starget->can_queue > 0)
1536		atomic_inc(&starget->target_busy);
1537
1538	blk_complete_request(req);
1539}
1540
1541static void scsi_softirq_done(struct request *rq)
1542{
1543	struct scsi_cmnd *cmd = rq->special;
1544	unsigned long wait_for = (cmd->allowed + 1) * rq->timeout;
1545	int disposition;
1546
1547	INIT_LIST_HEAD(&cmd->eh_entry);
1548
1549	atomic_inc(&cmd->device->iodone_cnt);
1550	if (cmd->result)
1551		atomic_inc(&cmd->device->ioerr_cnt);
1552
1553	disposition = scsi_decide_disposition(cmd);
1554	if (disposition != SUCCESS &&
1555	    time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
1556		sdev_printk(KERN_ERR, cmd->device,
1557			    "timing out command, waited %lus\n",
1558			    wait_for/HZ);
1559		disposition = SUCCESS;
1560	}
1561
1562	scsi_log_completion(cmd, disposition);
1563
1564	switch (disposition) {
1565		case SUCCESS:
1566			scsi_finish_command(cmd);
1567			break;
1568		case NEEDS_RETRY:
1569			scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
1570			break;
1571		case ADD_TO_MLQUEUE:
1572			scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1573			break;
1574		default:
1575			if (!scsi_eh_scmd_add(cmd, 0))
1576				scsi_finish_command(cmd);
1577	}
1578}
1579
1580/**
1581 * scsi_dispatch_command - Dispatch a command to the low-level driver.
1582 * @cmd: command block we are dispatching.
1583 *
1584 * Return: nonzero return request was rejected and device's queue needs to be
1585 * plugged.
1586 */
1587static int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
1588{
1589	struct Scsi_Host *host = cmd->device->host;
1590	int rtn = 0;
1591
1592	atomic_inc(&cmd->device->iorequest_cnt);
1593
1594	/* check if the device is still usable */
1595	if (unlikely(cmd->device->sdev_state == SDEV_DEL)) {
1596		/* in SDEV_DEL we error all commands. DID_NO_CONNECT
1597		 * returns an immediate error upwards, and signals
1598		 * that the device is no longer present */
1599		cmd->result = DID_NO_CONNECT << 16;
1600		goto done;
1601	}
1602
1603	/* Check to see if the scsi lld made this device blocked. */
1604	if (unlikely(scsi_device_blocked(cmd->device))) {
1605		/*
1606		 * in blocked state, the command is just put back on
1607		 * the device queue.  The suspend state has already
1608		 * blocked the queue so future requests should not
1609		 * occur until the device transitions out of the
1610		 * suspend state.
1611		 */
1612		SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
1613			"queuecommand : device blocked\n"));
1614		return SCSI_MLQUEUE_DEVICE_BUSY;
1615	}
1616
1617	/* Store the LUN value in cmnd, if needed. */
1618	if (cmd->device->lun_in_cdb)
1619		cmd->cmnd[1] = (cmd->cmnd[1] & 0x1f) |
1620			       (cmd->device->lun << 5 & 0xe0);
1621
1622	scsi_log_send(cmd);
1623
1624	/*
1625	 * Before we queue this command, check if the command
1626	 * length exceeds what the host adapter can handle.
1627	 */
1628	if (cmd->cmd_len > cmd->device->host->max_cmd_len) {
1629		SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
1630			       "queuecommand : command too long. "
1631			       "cdb_size=%d host->max_cmd_len=%d\n",
1632			       cmd->cmd_len, cmd->device->host->max_cmd_len));
1633		cmd->result = (DID_ABORT << 16);
1634		goto done;
1635	}
1636
1637	if (unlikely(host->shost_state == SHOST_DEL)) {
1638		cmd->result = (DID_NO_CONNECT << 16);
1639		goto done;
1640
1641	}
1642
1643	trace_scsi_dispatch_cmd_start(cmd);
1644	rtn = host->hostt->queuecommand(host, cmd);
1645	if (rtn) {
1646		trace_scsi_dispatch_cmd_error(cmd, rtn);
1647		if (rtn != SCSI_MLQUEUE_DEVICE_BUSY &&
1648		    rtn != SCSI_MLQUEUE_TARGET_BUSY)
1649			rtn = SCSI_MLQUEUE_HOST_BUSY;
1650
1651		SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
1652			"queuecommand : request rejected\n"));
1653	}
1654
1655	return rtn;
1656 done:
1657	cmd->scsi_done(cmd);
1658	return 0;
1659}
1660
1661/**
1662 * scsi_done - Invoke completion on finished SCSI command.
1663 * @cmd: The SCSI Command for which a low-level device driver (LLDD) gives
1664 * ownership back to SCSI Core -- i.e. the LLDD has finished with it.
1665 *
1666 * Description: This function is the mid-level's (SCSI Core) interrupt routine,
1667 * which regains ownership of the SCSI command (de facto) from a LLDD, and
1668 * calls blk_complete_request() for further processing.
1669 *
1670 * This function is interrupt context safe.
1671 */
1672static void scsi_done(struct scsi_cmnd *cmd)
1673{
1674	trace_scsi_dispatch_cmd_done(cmd);
1675	blk_complete_request(cmd->request);
1676}
1677
1678/*
1679 * Function:    scsi_request_fn()
1680 *
1681 * Purpose:     Main strategy routine for SCSI.
1682 *
1683 * Arguments:   q       - Pointer to actual queue.
1684 *
1685 * Returns:     Nothing
1686 *
1687 * Lock status: IO request lock assumed to be held when called.
1688 */
1689static void scsi_request_fn(struct request_queue *q)
1690	__releases(q->queue_lock)
1691	__acquires(q->queue_lock)
1692{
1693	struct scsi_device *sdev = q->queuedata;
1694	struct Scsi_Host *shost;
1695	struct scsi_cmnd *cmd;
1696	struct request *req;
1697
1698	/*
1699	 * To start with, we keep looping until the queue is empty, or until
1700	 * the host is no longer able to accept any more requests.
1701	 */
1702	shost = sdev->host;
1703	for (;;) {
1704		int rtn;
1705		/*
1706		 * get next queueable request.  We do this early to make sure
1707		 * that the request is fully prepared even if we cannot
1708		 * accept it.
1709		 */
1710		req = blk_peek_request(q);
1711		if (!req)
1712			break;
1713
1714		if (unlikely(!scsi_device_online(sdev))) {
1715			sdev_printk(KERN_ERR, sdev,
1716				    "rejecting I/O to offline device\n");
1717			scsi_kill_request(req, q);
1718			continue;
1719		}
1720
1721		if (!scsi_dev_queue_ready(q, sdev))
1722			break;
1723
1724		/*
1725		 * Remove the request from the request list.
1726		 */
1727		if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1728			blk_start_request(req);
1729
1730		spin_unlock_irq(q->queue_lock);
1731		cmd = req->special;
1732		if (unlikely(cmd == NULL)) {
1733			printk(KERN_CRIT "impossible request in %s.\n"
1734					 "please mail a stack trace to "
1735					 "linux-scsi@vger.kernel.org\n",
1736					 __func__);
1737			blk_dump_rq_flags(req, "foo");
1738			BUG();
1739		}
1740
1741		/*
1742		 * We hit this when the driver is using a host wide
1743		 * tag map. For device level tag maps the queue_depth check
1744		 * in the device ready fn would prevent us from trying
1745		 * to allocate a tag. Since the map is a shared host resource
1746		 * we add the dev to the starved list so it eventually gets
1747		 * a run when a tag is freed.
1748		 */
1749		if (blk_queue_tagged(q) && !(req->rq_flags & RQF_QUEUED)) {
1750			spin_lock_irq(shost->host_lock);
1751			if (list_empty(&sdev->starved_entry))
1752				list_add_tail(&sdev->starved_entry,
1753					      &shost->starved_list);
1754			spin_unlock_irq(shost->host_lock);
1755			goto not_ready;
1756		}
1757
1758		if (!scsi_target_queue_ready(shost, sdev))
1759			goto not_ready;
1760
1761		if (!scsi_host_queue_ready(q, shost, sdev))
1762			goto host_not_ready;
1763	
1764		if (sdev->simple_tags)
1765			cmd->flags |= SCMD_TAGGED;
1766		else
1767			cmd->flags &= ~SCMD_TAGGED;
1768
1769		/*
1770		 * Finally, initialize any error handling parameters, and set up
1771		 * the timers for timeouts.
1772		 */
1773		scsi_init_cmd_errh(cmd);
1774
1775		/*
1776		 * Dispatch the command to the low-level driver.
1777		 */
1778		cmd->scsi_done = scsi_done;
1779		rtn = scsi_dispatch_cmd(cmd);
1780		if (rtn) {
1781			scsi_queue_insert(cmd, rtn);
1782			spin_lock_irq(q->queue_lock);
1783			goto out_delay;
1784		}
1785		spin_lock_irq(q->queue_lock);
1786	}
1787
1788	return;
1789
1790 host_not_ready:
1791	if (scsi_target(sdev)->can_queue > 0)
1792		atomic_dec(&scsi_target(sdev)->target_busy);
1793 not_ready:
1794	/*
1795	 * lock q, handle tag, requeue req, and decrement device_busy. We
1796	 * must return with queue_lock held.
1797	 *
1798	 * Decrementing device_busy without checking it is OK, as all such
1799	 * cases (host limits or settings) should run the queue at some
1800	 * later time.
1801	 */
1802	spin_lock_irq(q->queue_lock);
1803	blk_requeue_request(q, req);
1804	atomic_dec(&sdev->device_busy);
1805out_delay:
1806	if (!atomic_read(&sdev->device_busy) && !scsi_device_blocked(sdev))
1807		blk_delay_queue(q, SCSI_QUEUE_DELAY);
1808}
1809
1810static inline int prep_to_mq(int ret)
1811{
1812	switch (ret) {
1813	case BLKPREP_OK:
1814		return BLK_MQ_RQ_QUEUE_OK;
1815	case BLKPREP_DEFER:
1816		return BLK_MQ_RQ_QUEUE_BUSY;
1817	default:
1818		return BLK_MQ_RQ_QUEUE_ERROR;
1819	}
1820}
1821
1822static int scsi_mq_prep_fn(struct request *req)
1823{
1824	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
1825	struct scsi_device *sdev = req->q->queuedata;
1826	struct Scsi_Host *shost = sdev->host;
1827	unsigned char *sense_buf = cmd->sense_buffer;
1828	struct scatterlist *sg;
1829
1830	memset(cmd, 0, sizeof(struct scsi_cmnd));
1831
1832	req->special = cmd;
1833
1834	cmd->request = req;
1835	cmd->device = sdev;
1836	cmd->sense_buffer = sense_buf;
1837
1838	cmd->tag = req->tag;
1839
1840	cmd->cmnd = req->cmd;
1841	cmd->prot_op = SCSI_PROT_NORMAL;
1842
1843	INIT_LIST_HEAD(&cmd->list);
1844	INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
1845	cmd->jiffies_at_alloc = jiffies;
1846
1847	if (shost->use_cmd_list) {
1848		spin_lock_irq(&sdev->list_lock);
1849		list_add_tail(&cmd->list, &sdev->cmd_list);
1850		spin_unlock_irq(&sdev->list_lock);
1851	}
1852
1853	sg = (void *)cmd + sizeof(struct scsi_cmnd) + shost->hostt->cmd_size;
1854	cmd->sdb.table.sgl = sg;
1855
1856	if (scsi_host_get_prot(shost)) {
1857		cmd->prot_sdb = (void *)sg +
1858			min_t(unsigned int,
1859			      shost->sg_tablesize, SG_CHUNK_SIZE) *
1860			sizeof(struct scatterlist);
1861		memset(cmd->prot_sdb, 0, sizeof(struct scsi_data_buffer));
1862
1863		cmd->prot_sdb->table.sgl =
1864			(struct scatterlist *)(cmd->prot_sdb + 1);
1865	}
1866
1867	if (blk_bidi_rq(req)) {
1868		struct request *next_rq = req->next_rq;
1869		struct scsi_data_buffer *bidi_sdb = blk_mq_rq_to_pdu(next_rq);
1870
1871		memset(bidi_sdb, 0, sizeof(struct scsi_data_buffer));
1872		bidi_sdb->table.sgl =
1873			(struct scatterlist *)(bidi_sdb + 1);
1874
1875		next_rq->special = bidi_sdb;
1876	}
1877
1878	blk_mq_start_request(req);
 
 
1879
1880	return scsi_setup_cmnd(sdev, req);
 
 
1881}
1882
1883static void scsi_mq_done(struct scsi_cmnd *cmd)
1884{
 
 
 
 
1885	trace_scsi_dispatch_cmd_done(cmd);
1886	blk_mq_complete_request(cmd->request, cmd->request->errors);
 
 
 
 
 
 
 
1887}
1888
1889static int scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1890			 const struct blk_mq_queue_data *bd)
1891{
1892	struct request *req = bd->rq;
1893	struct request_queue *q = req->q;
1894	struct scsi_device *sdev = q->queuedata;
1895	struct Scsi_Host *shost = sdev->host;
1896	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
1897	int ret;
1898	int reason;
1899
1900	ret = prep_to_mq(scsi_prep_state_check(sdev, req));
1901	if (ret != BLK_MQ_RQ_QUEUE_OK)
1902		goto out;
1903
1904	ret = BLK_MQ_RQ_QUEUE_BUSY;
1905	if (!get_device(&sdev->sdev_gendev))
1906		goto out;
 
 
 
 
 
 
1907
1908	if (!scsi_dev_queue_ready(q, sdev))
1909		goto out_put_device;
1910	if (!scsi_target_queue_ready(shost, sdev))
1911		goto out_dec_device_busy;
1912	if (!scsi_host_queue_ready(q, shost, sdev))
1913		goto out_dec_target_busy;
1914
1915
1916	if (!(req->rq_flags & RQF_DONTPREP)) {
1917		ret = prep_to_mq(scsi_mq_prep_fn(req));
1918		if (ret != BLK_MQ_RQ_QUEUE_OK)
1919			goto out_dec_host_busy;
1920		req->rq_flags |= RQF_DONTPREP;
1921	} else {
1922		blk_mq_start_request(req);
1923	}
1924
 
1925	if (sdev->simple_tags)
1926		cmd->flags |= SCMD_TAGGED;
1927	else
1928		cmd->flags &= ~SCMD_TAGGED;
1929
1930	scsi_init_cmd_errh(cmd);
 
1931	cmd->scsi_done = scsi_mq_done;
1932
 
1933	reason = scsi_dispatch_cmd(cmd);
1934	if (reason) {
1935		scsi_set_blocked(cmd, reason);
1936		ret = BLK_MQ_RQ_QUEUE_BUSY;
1937		goto out_dec_host_busy;
1938	}
1939
1940	return BLK_MQ_RQ_QUEUE_OK;
1941
1942out_dec_host_busy:
1943	atomic_dec(&shost->host_busy);
1944out_dec_target_busy:
1945	if (scsi_target(sdev)->can_queue > 0)
1946		atomic_dec(&scsi_target(sdev)->target_busy);
1947out_dec_device_busy:
1948	atomic_dec(&sdev->device_busy);
1949out_put_device:
1950	put_device(&sdev->sdev_gendev);
1951out:
1952	switch (ret) {
1953	case BLK_MQ_RQ_QUEUE_BUSY:
1954		if (atomic_read(&sdev->device_busy) == 0 &&
1955		    !scsi_device_blocked(sdev))
1956			blk_mq_delay_queue(hctx, SCSI_QUEUE_DELAY);
 
 
1957		break;
1958	case BLK_MQ_RQ_QUEUE_ERROR:
 
 
 
 
 
 
 
 
 
1959		/*
1960		 * Make sure to release all allocated ressources when
1961		 * we hit an error, as we will never see this command
1962		 * again.
1963		 */
1964		if (req->rq_flags & RQF_DONTPREP)
1965			scsi_mq_uninit_cmd(cmd);
1966		break;
1967	default:
1968		break;
1969	}
1970	return ret;
1971}
1972
1973static enum blk_eh_timer_return scsi_timeout(struct request *req,
1974		bool reserved)
1975{
1976	if (reserved)
1977		return BLK_EH_RESET_TIMER;
1978	return scsi_times_out(req);
1979}
1980
1981static int scsi_init_request(void *data, struct request *rq,
1982		unsigned int hctx_idx, unsigned int request_idx,
1983		unsigned int numa_node)
1984{
 
1985	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
 
 
1986
1987	cmd->sense_buffer = kzalloc_node(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL,
1988			numa_node);
1989	if (!cmd->sense_buffer)
1990		return -ENOMEM;
1991	return 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1992}
1993
1994static void scsi_exit_request(void *data, struct request *rq,
1995		unsigned int hctx_idx, unsigned int request_idx)
1996{
 
1997	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
1998
1999	kfree(cmd->sense_buffer);
 
 
2000}
2001
2002static int scsi_map_queues(struct blk_mq_tag_set *set)
 
2003{
2004	struct Scsi_Host *shost = container_of(set, struct Scsi_Host, tag_set);
2005
2006	if (shost->hostt->map_queues)
2007		return shost->hostt->map_queues(shost);
2008	return blk_mq_map_queues(set);
 
2009}
2010
2011static u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
 
2012{
2013	struct device *host_dev;
2014	u64 bounce_limit = 0xffffffff;
2015
2016	if (shost->unchecked_isa_dma)
2017		return BLK_BOUNCE_ISA;
2018	/*
2019	 * Platforms with virtual-DMA translation
2020	 * hardware have no practical limit.
2021	 */
2022	if (!PCI_DMA_BUS_IS_PHYS)
2023		return BLK_BOUNCE_ANY;
2024
2025	host_dev = scsi_get_device(shost);
2026	if (host_dev && host_dev->dma_mask)
2027		bounce_limit = (u64)dma_max_pfn(host_dev) << PAGE_SHIFT;
2028
2029	return bounce_limit;
 
 
2030}
2031
2032static void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q)
2033{
2034	struct device *dev = shost->dma_dev;
2035
2036	/*
2037	 * this limit is imposed by hardware restrictions
2038	 */
2039	blk_queue_max_segments(q, min_t(unsigned short, shost->sg_tablesize,
2040					SG_MAX_SEGMENTS));
2041
2042	if (scsi_host_prot_dma(shost)) {
2043		shost->sg_prot_tablesize =
2044			min_not_zero(shost->sg_prot_tablesize,
2045				     (unsigned short)SCSI_MAX_PROT_SG_SEGMENTS);
2046		BUG_ON(shost->sg_prot_tablesize < shost->sg_tablesize);
2047		blk_queue_max_integrity_segments(q, shost->sg_prot_tablesize);
2048	}
2049
 
 
 
 
2050	blk_queue_max_hw_sectors(q, shost->max_sectors);
2051	blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
2052	blk_queue_segment_boundary(q, shost->dma_boundary);
2053	dma_set_seg_boundary(dev, shost->dma_boundary);
2054
2055	blk_queue_max_segment_size(q, dma_get_max_seg_size(dev));
2056
2057	if (!shost->use_clustering)
2058		q->limits.cluster = 0;
2059
2060	/*
2061	 * set a reasonable default alignment on word boundaries: the
2062	 * host and device may alter it using
2063	 * blk_queue_update_dma_alignment() later.
 
 
2064	 */
2065	blk_queue_dma_alignment(q, 0x03);
2066}
 
2067
2068struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
2069					 request_fn_proc *request_fn)
2070{
2071	struct request_queue *q;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2072
2073	q = blk_init_queue(request_fn, NULL);
2074	if (!q)
2075		return NULL;
2076	__scsi_init_queue(shost, q);
2077	return q;
2078}
2079EXPORT_SYMBOL(__scsi_alloc_queue);
2080
2081struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
2082{
2083	struct request_queue *q;
2084
2085	q = __scsi_alloc_queue(sdev->host, scsi_request_fn);
2086	if (!q)
2087		return NULL;
2088
2089	blk_queue_prep_rq(q, scsi_prep_fn);
2090	blk_queue_unprep_rq(q, scsi_unprep_fn);
2091	blk_queue_softirq_done(q, scsi_softirq_done);
2092	blk_queue_rq_timed_out(q, scsi_times_out);
2093	blk_queue_lld_busy(q, scsi_lld_busy);
2094	return q;
2095}
2096
2097static struct blk_mq_ops scsi_mq_ops = {
 
 
2098	.queue_rq	= scsi_queue_rq,
2099	.complete	= scsi_softirq_done,
 
2100	.timeout	= scsi_timeout,
2101	.init_request	= scsi_init_request,
2102	.exit_request	= scsi_exit_request,
 
 
 
 
 
 
2103	.map_queues	= scsi_map_queues,
 
 
 
 
2104};
2105
2106struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev)
2107{
2108	sdev->request_queue = blk_mq_init_queue(&sdev->host->tag_set);
2109	if (IS_ERR(sdev->request_queue))
2110		return NULL;
2111
2112	sdev->request_queue->queuedata = sdev;
2113	__scsi_init_queue(sdev->host, sdev->request_queue);
2114	return sdev->request_queue;
2115}
2116
2117int scsi_mq_setup_tags(struct Scsi_Host *shost)
2118{
2119	unsigned int cmd_size, sgl_size, tbl_size;
 
2120
2121	tbl_size = shost->sg_tablesize;
2122	if (tbl_size > SG_CHUNK_SIZE)
2123		tbl_size = SG_CHUNK_SIZE;
2124	sgl_size = tbl_size * sizeof(struct scatterlist);
2125	cmd_size = sizeof(struct scsi_cmnd) + shost->hostt->cmd_size + sgl_size;
2126	if (scsi_host_get_prot(shost))
2127		cmd_size += sizeof(struct scsi_data_buffer) + sgl_size;
 
2128
2129	memset(&shost->tag_set, 0, sizeof(shost->tag_set));
2130	shost->tag_set.ops = &scsi_mq_ops;
2131	shost->tag_set.nr_hw_queues = shost->nr_hw_queues ? : 1;
2132	shost->tag_set.queue_depth = shost->can_queue;
2133	shost->tag_set.cmd_size = cmd_size;
2134	shost->tag_set.numa_node = NUMA_NO_NODE;
2135	shost->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
2136	shost->tag_set.flags |=
 
 
 
 
2137		BLK_ALLOC_POLICY_TO_MQ_FLAG(shost->hostt->tag_alloc_policy);
2138	shost->tag_set.driver_data = shost;
 
 
2139
2140	return blk_mq_alloc_tag_set(&shost->tag_set);
2141}
2142
2143void scsi_mq_destroy_tags(struct Scsi_Host *shost)
2144{
2145	blk_mq_free_tag_set(&shost->tag_set);
2146}
2147
2148/**
2149 * scsi_device_from_queue - return sdev associated with a request_queue
2150 * @q: The request queue to return the sdev from
2151 *
2152 * Return the sdev associated with a request queue or NULL if the
2153 * request_queue does not reference a SCSI device.
2154 */
2155struct scsi_device *scsi_device_from_queue(struct request_queue *q)
2156{
2157	struct scsi_device *sdev = NULL;
2158
2159	if (q->mq_ops) {
2160		if (q->mq_ops == &scsi_mq_ops)
2161			sdev = q->queuedata;
2162	} else if (q->request_fn == scsi_request_fn)
2163		sdev = q->queuedata;
2164	if (!sdev || !get_device(&sdev->sdev_gendev))
2165		sdev = NULL;
2166
2167	return sdev;
2168}
2169EXPORT_SYMBOL_GPL(scsi_device_from_queue);
2170
2171/*
2172 * Function:    scsi_block_requests()
2173 *
2174 * Purpose:     Utility function used by low-level drivers to prevent further
2175 *		commands from being queued to the device.
2176 *
2177 * Arguments:   shost       - Host in question
2178 *
2179 * Returns:     Nothing
2180 *
2181 * Lock status: No locks are assumed held.
2182 *
2183 * Notes:       There is no timer nor any other means by which the requests
2184 *		get unblocked other than the low-level driver calling
2185 *		scsi_unblock_requests().
2186 */
2187void scsi_block_requests(struct Scsi_Host *shost)
2188{
2189	shost->host_self_blocked = 1;
2190}
2191EXPORT_SYMBOL(scsi_block_requests);
2192
2193/*
2194 * Function:    scsi_unblock_requests()
2195 *
2196 * Purpose:     Utility function used by low-level drivers to allow further
2197 *		commands from being queued to the device.
2198 *
2199 * Arguments:   shost       - Host in question
2200 *
2201 * Returns:     Nothing
2202 *
2203 * Lock status: No locks are assumed held.
2204 *
2205 * Notes:       There is no timer nor any other means by which the requests
2206 *		get unblocked other than the low-level driver calling
2207 *		scsi_unblock_requests().
2208 *
2209 *		This is done as an API function so that changes to the
2210 *		internals of the scsi mid-layer won't require wholesale
2211 *		changes to drivers that use this feature.
2212 */
2213void scsi_unblock_requests(struct Scsi_Host *shost)
2214{
2215	shost->host_self_blocked = 0;
2216	scsi_run_host_queues(shost);
2217}
2218EXPORT_SYMBOL(scsi_unblock_requests);
2219
2220int __init scsi_init_queue(void)
2221{
2222	scsi_sdb_cache = kmem_cache_create("scsi_data_buffer",
2223					   sizeof(struct scsi_data_buffer),
2224					   0, 0, NULL);
2225	if (!scsi_sdb_cache) {
2226		printk(KERN_ERR "SCSI: can't init scsi sdb cache\n");
2227		return -ENOMEM;
2228	}
2229
2230	return 0;
2231}
2232
2233void scsi_exit_queue(void)
2234{
2235	kmem_cache_destroy(scsi_sdb_cache);
2236}
2237
2238/**
2239 *	scsi_mode_select - issue a mode select
2240 *	@sdev:	SCSI device to be queried
2241 *	@pf:	Page format bit (1 == standard, 0 == vendor specific)
2242 *	@sp:	Save page bit (0 == don't save, 1 == save)
2243 *	@modepage: mode page being requested
2244 *	@buffer: request buffer (may not be smaller than eight bytes)
2245 *	@len:	length of request buffer.
2246 *	@timeout: command timeout
2247 *	@retries: number of retries before failing
2248 *	@data: returns a structure abstracting the mode header data
2249 *	@sshdr: place to put sense data (or NULL if no sense to be collected).
2250 *		must be SCSI_SENSE_BUFFERSIZE big.
2251 *
2252 *	Returns zero if successful; negative error number or scsi
2253 *	status on error
2254 *
2255 */
2256int
2257scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
2258		 unsigned char *buffer, int len, int timeout, int retries,
2259		 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
2260{
2261	unsigned char cmd[10];
2262	unsigned char *real_buffer;
2263	int ret;
2264
2265	memset(cmd, 0, sizeof(cmd));
2266	cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
2267
2268	if (sdev->use_10_for_ms) {
2269		if (len > 65535)
2270			return -EINVAL;
2271		real_buffer = kmalloc(8 + len, GFP_KERNEL);
2272		if (!real_buffer)
2273			return -ENOMEM;
2274		memcpy(real_buffer + 8, buffer, len);
2275		len += 8;
2276		real_buffer[0] = 0;
2277		real_buffer[1] = 0;
2278		real_buffer[2] = data->medium_type;
2279		real_buffer[3] = data->device_specific;
2280		real_buffer[4] = data->longlba ? 0x01 : 0;
2281		real_buffer[5] = 0;
2282		real_buffer[6] = data->block_descriptor_length >> 8;
2283		real_buffer[7] = data->block_descriptor_length;
2284
2285		cmd[0] = MODE_SELECT_10;
2286		cmd[7] = len >> 8;
2287		cmd[8] = len;
2288	} else {
2289		if (len > 255 || data->block_descriptor_length > 255 ||
2290		    data->longlba)
2291			return -EINVAL;
2292
2293		real_buffer = kmalloc(4 + len, GFP_KERNEL);
2294		if (!real_buffer)
2295			return -ENOMEM;
2296		memcpy(real_buffer + 4, buffer, len);
2297		len += 4;
2298		real_buffer[0] = 0;
2299		real_buffer[1] = data->medium_type;
2300		real_buffer[2] = data->device_specific;
2301		real_buffer[3] = data->block_descriptor_length;
2302		
2303
2304		cmd[0] = MODE_SELECT;
2305		cmd[4] = len;
2306	}
2307
2308	ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
2309			       sshdr, timeout, retries, NULL);
2310	kfree(real_buffer);
2311	return ret;
2312}
2313EXPORT_SYMBOL_GPL(scsi_mode_select);
2314
2315/**
2316 *	scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
2317 *	@sdev:	SCSI device to be queried
2318 *	@dbd:	set if mode sense will allow block descriptors to be returned
2319 *	@modepage: mode page being requested
2320 *	@buffer: request buffer (may not be smaller than eight bytes)
2321 *	@len:	length of request buffer.
2322 *	@timeout: command timeout
2323 *	@retries: number of retries before failing
2324 *	@data: returns a structure abstracting the mode header data
2325 *	@sshdr: place to put sense data (or NULL if no sense to be collected).
2326 *		must be SCSI_SENSE_BUFFERSIZE big.
2327 *
2328 *	Returns zero if unsuccessful, or the header offset (either 4
2329 *	or 8 depending on whether a six or ten byte command was
2330 *	issued) if successful.
2331 */
2332int
2333scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
2334		  unsigned char *buffer, int len, int timeout, int retries,
2335		  struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
2336{
2337	unsigned char cmd[12];
2338	int use_10_for_ms;
2339	int header_length;
2340	int result, retry_count = retries;
2341	struct scsi_sense_hdr my_sshdr;
2342
2343	memset(data, 0, sizeof(*data));
2344	memset(&cmd[0], 0, 12);
 
 
2345	cmd[1] = dbd & 0x18;	/* allows DBD and LLBA bits */
2346	cmd[2] = modepage;
2347
2348	/* caller might not be interested in sense, but we need it */
2349	if (!sshdr)
2350		sshdr = &my_sshdr;
2351
2352 retry:
2353	use_10_for_ms = sdev->use_10_for_ms;
2354
2355	if (use_10_for_ms) {
2356		if (len < 8)
2357			len = 8;
2358
2359		cmd[0] = MODE_SENSE_10;
2360		cmd[8] = len;
2361		header_length = 8;
2362	} else {
2363		if (len < 4)
2364			len = 4;
2365
2366		cmd[0] = MODE_SENSE;
2367		cmd[4] = len;
2368		header_length = 4;
2369	}
2370
2371	memset(buffer, 0, len);
2372
2373	result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
2374				  sshdr, timeout, retries, NULL);
 
 
2375
2376	/* This code looks awful: what it's doing is making sure an
2377	 * ILLEGAL REQUEST sense return identifies the actual command
2378	 * byte as the problem.  MODE_SENSE commands can return
2379	 * ILLEGAL REQUEST if the code page isn't supported */
2380
2381	if (use_10_for_ms && !scsi_status_is_good(result) &&
2382	    (driver_byte(result) & DRIVER_SENSE)) {
2383		if (scsi_sense_valid(sshdr)) {
2384			if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
2385			    (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
2386				/* 
2387				 * Invalid command operation code
2388				 */
2389				sdev->use_10_for_ms = 0;
 
 
 
 
 
 
 
 
2390				goto retry;
2391			}
2392		}
 
2393	}
2394
2395	if(scsi_status_is_good(result)) {
2396		if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
2397			     (modepage == 6 || modepage == 8))) {
2398			/* Initio breakage? */
2399			header_length = 0;
2400			data->length = 13;
2401			data->medium_type = 0;
2402			data->device_specific = 0;
2403			data->longlba = 0;
2404			data->block_descriptor_length = 0;
2405		} else if(use_10_for_ms) {
2406			data->length = buffer[0]*256 + buffer[1] + 2;
2407			data->medium_type = buffer[2];
2408			data->device_specific = buffer[3];
2409			data->longlba = buffer[4] & 0x01;
2410			data->block_descriptor_length = buffer[6]*256
2411				+ buffer[7];
2412		} else {
2413			data->length = buffer[0] + 1;
2414			data->medium_type = buffer[1];
2415			data->device_specific = buffer[2];
2416			data->block_descriptor_length = buffer[3];
2417		}
2418		data->header_length = header_length;
2419	} else if ((status_byte(result) == CHECK_CONDITION) &&
2420		   scsi_sense_valid(sshdr) &&
2421		   sshdr->sense_key == UNIT_ATTENTION && retry_count) {
2422		retry_count--;
2423		goto retry;
2424	}
 
2425
2426	return result;
2427}
2428EXPORT_SYMBOL(scsi_mode_sense);
2429
2430/**
2431 *	scsi_test_unit_ready - test if unit is ready
2432 *	@sdev:	scsi device to change the state of.
2433 *	@timeout: command timeout
2434 *	@retries: number of retries before failing
2435 *	@sshdr_external: Optional pointer to struct scsi_sense_hdr for
2436 *		returning sense. Make sure that this is cleared before passing
2437 *		in.
2438 *
2439 *	Returns zero if unsuccessful or an error if TUR failed.  For
2440 *	removable media, UNIT_ATTENTION sets ->changed flag.
2441 **/
2442int
2443scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
2444		     struct scsi_sense_hdr *sshdr_external)
2445{
2446	char cmd[] = {
2447		TEST_UNIT_READY, 0, 0, 0, 0, 0,
2448	};
2449	struct scsi_sense_hdr *sshdr;
2450	int result;
2451
2452	if (!sshdr_external)
2453		sshdr = kzalloc(sizeof(*sshdr), GFP_KERNEL);
2454	else
2455		sshdr = sshdr_external;
2456
2457	/* try to eat the UNIT_ATTENTION if there are enough retries */
2458	do {
2459		result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
2460					  timeout, retries, NULL);
2461		if (sdev->removable && scsi_sense_valid(sshdr) &&
2462		    sshdr->sense_key == UNIT_ATTENTION)
2463			sdev->changed = 1;
2464	} while (scsi_sense_valid(sshdr) &&
2465		 sshdr->sense_key == UNIT_ATTENTION && --retries);
2466
2467	if (!sshdr_external)
2468		kfree(sshdr);
2469	return result;
2470}
2471EXPORT_SYMBOL(scsi_test_unit_ready);
2472
2473/**
2474 *	scsi_device_set_state - Take the given device through the device state model.
2475 *	@sdev:	scsi device to change the state of.
2476 *	@state:	state to change to.
2477 *
2478 *	Returns zero if unsuccessful or an error if the requested 
2479 *	transition is illegal.
2480 */
2481int
2482scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
2483{
2484	enum scsi_device_state oldstate = sdev->sdev_state;
2485
2486	if (state == oldstate)
2487		return 0;
2488
2489	switch (state) {
2490	case SDEV_CREATED:
2491		switch (oldstate) {
2492		case SDEV_CREATED_BLOCK:
2493			break;
2494		default:
2495			goto illegal;
2496		}
2497		break;
2498			
2499	case SDEV_RUNNING:
2500		switch (oldstate) {
2501		case SDEV_CREATED:
2502		case SDEV_OFFLINE:
2503		case SDEV_TRANSPORT_OFFLINE:
2504		case SDEV_QUIESCE:
2505		case SDEV_BLOCK:
2506			break;
2507		default:
2508			goto illegal;
2509		}
2510		break;
2511
2512	case SDEV_QUIESCE:
2513		switch (oldstate) {
2514		case SDEV_RUNNING:
2515		case SDEV_OFFLINE:
2516		case SDEV_TRANSPORT_OFFLINE:
2517			break;
2518		default:
2519			goto illegal;
2520		}
2521		break;
2522
2523	case SDEV_OFFLINE:
2524	case SDEV_TRANSPORT_OFFLINE:
2525		switch (oldstate) {
2526		case SDEV_CREATED:
2527		case SDEV_RUNNING:
2528		case SDEV_QUIESCE:
2529		case SDEV_BLOCK:
2530			break;
2531		default:
2532			goto illegal;
2533		}
2534		break;
2535
2536	case SDEV_BLOCK:
2537		switch (oldstate) {
2538		case SDEV_RUNNING:
2539		case SDEV_CREATED_BLOCK:
 
 
2540			break;
2541		default:
2542			goto illegal;
2543		}
2544		break;
2545
2546	case SDEV_CREATED_BLOCK:
2547		switch (oldstate) {
2548		case SDEV_CREATED:
2549			break;
2550		default:
2551			goto illegal;
2552		}
2553		break;
2554
2555	case SDEV_CANCEL:
2556		switch (oldstate) {
2557		case SDEV_CREATED:
2558		case SDEV_RUNNING:
2559		case SDEV_QUIESCE:
2560		case SDEV_OFFLINE:
2561		case SDEV_TRANSPORT_OFFLINE:
2562		case SDEV_BLOCK:
2563			break;
2564		default:
2565			goto illegal;
2566		}
2567		break;
2568
2569	case SDEV_DEL:
2570		switch (oldstate) {
2571		case SDEV_CREATED:
2572		case SDEV_RUNNING:
2573		case SDEV_OFFLINE:
2574		case SDEV_TRANSPORT_OFFLINE:
2575		case SDEV_CANCEL:
 
2576		case SDEV_CREATED_BLOCK:
2577			break;
2578		default:
2579			goto illegal;
2580		}
2581		break;
2582
2583	}
 
2584	sdev->sdev_state = state;
2585	return 0;
2586
2587 illegal:
2588	SCSI_LOG_ERROR_RECOVERY(1,
2589				sdev_printk(KERN_ERR, sdev,
2590					    "Illegal state transition %s->%s",
2591					    scsi_device_state_name(oldstate),
2592					    scsi_device_state_name(state))
2593				);
2594	return -EINVAL;
2595}
2596EXPORT_SYMBOL(scsi_device_set_state);
2597
2598/**
2599 * 	sdev_evt_emit - emit a single SCSI device uevent
2600 *	@sdev: associated SCSI device
2601 *	@evt: event to emit
2602 *
2603 *	Send a single uevent (scsi_event) to the associated scsi_device.
2604 */
2605static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt)
2606{
2607	int idx = 0;
2608	char *envp[3];
2609
2610	switch (evt->evt_type) {
2611	case SDEV_EVT_MEDIA_CHANGE:
2612		envp[idx++] = "SDEV_MEDIA_CHANGE=1";
2613		break;
2614	case SDEV_EVT_INQUIRY_CHANGE_REPORTED:
2615		scsi_rescan_device(&sdev->sdev_gendev);
2616		envp[idx++] = "SDEV_UA=INQUIRY_DATA_HAS_CHANGED";
2617		break;
2618	case SDEV_EVT_CAPACITY_CHANGE_REPORTED:
2619		envp[idx++] = "SDEV_UA=CAPACITY_DATA_HAS_CHANGED";
2620		break;
2621	case SDEV_EVT_SOFT_THRESHOLD_REACHED_REPORTED:
2622	       envp[idx++] = "SDEV_UA=THIN_PROVISIONING_SOFT_THRESHOLD_REACHED";
2623		break;
2624	case SDEV_EVT_MODE_PARAMETER_CHANGE_REPORTED:
2625		envp[idx++] = "SDEV_UA=MODE_PARAMETERS_CHANGED";
2626		break;
2627	case SDEV_EVT_LUN_CHANGE_REPORTED:
2628		envp[idx++] = "SDEV_UA=REPORTED_LUNS_DATA_HAS_CHANGED";
2629		break;
2630	case SDEV_EVT_ALUA_STATE_CHANGE_REPORTED:
2631		envp[idx++] = "SDEV_UA=ASYMMETRIC_ACCESS_STATE_CHANGED";
2632		break;
 
 
 
2633	default:
2634		/* do nothing */
2635		break;
2636	}
2637
2638	envp[idx++] = NULL;
2639
2640	kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
2641}
2642
2643/**
2644 * 	sdev_evt_thread - send a uevent for each scsi event
2645 *	@work: work struct for scsi_device
2646 *
2647 *	Dispatch queued events to their associated scsi_device kobjects
2648 *	as uevents.
2649 */
2650void scsi_evt_thread(struct work_struct *work)
2651{
2652	struct scsi_device *sdev;
2653	enum scsi_device_event evt_type;
2654	LIST_HEAD(event_list);
2655
2656	sdev = container_of(work, struct scsi_device, event_work);
2657
2658	for (evt_type = SDEV_EVT_FIRST; evt_type <= SDEV_EVT_LAST; evt_type++)
2659		if (test_and_clear_bit(evt_type, sdev->pending_events))
2660			sdev_evt_send_simple(sdev, evt_type, GFP_KERNEL);
2661
2662	while (1) {
2663		struct scsi_event *evt;
2664		struct list_head *this, *tmp;
2665		unsigned long flags;
2666
2667		spin_lock_irqsave(&sdev->list_lock, flags);
2668		list_splice_init(&sdev->event_list, &event_list);
2669		spin_unlock_irqrestore(&sdev->list_lock, flags);
2670
2671		if (list_empty(&event_list))
2672			break;
2673
2674		list_for_each_safe(this, tmp, &event_list) {
2675			evt = list_entry(this, struct scsi_event, node);
2676			list_del(&evt->node);
2677			scsi_evt_emit(sdev, evt);
2678			kfree(evt);
2679		}
2680	}
2681}
2682
2683/**
2684 * 	sdev_evt_send - send asserted event to uevent thread
2685 *	@sdev: scsi_device event occurred on
2686 *	@evt: event to send
2687 *
2688 *	Assert scsi device event asynchronously.
2689 */
2690void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt)
2691{
2692	unsigned long flags;
2693
2694#if 0
2695	/* FIXME: currently this check eliminates all media change events
2696	 * for polled devices.  Need to update to discriminate between AN
2697	 * and polled events */
2698	if (!test_bit(evt->evt_type, sdev->supported_events)) {
2699		kfree(evt);
2700		return;
2701	}
2702#endif
2703
2704	spin_lock_irqsave(&sdev->list_lock, flags);
2705	list_add_tail(&evt->node, &sdev->event_list);
2706	schedule_work(&sdev->event_work);
2707	spin_unlock_irqrestore(&sdev->list_lock, flags);
2708}
2709EXPORT_SYMBOL_GPL(sdev_evt_send);
2710
2711/**
2712 * 	sdev_evt_alloc - allocate a new scsi event
2713 *	@evt_type: type of event to allocate
2714 *	@gfpflags: GFP flags for allocation
2715 *
2716 *	Allocates and returns a new scsi_event.
2717 */
2718struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
2719				  gfp_t gfpflags)
2720{
2721	struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags);
2722	if (!evt)
2723		return NULL;
2724
2725	evt->evt_type = evt_type;
2726	INIT_LIST_HEAD(&evt->node);
2727
2728	/* evt_type-specific initialization, if any */
2729	switch (evt_type) {
2730	case SDEV_EVT_MEDIA_CHANGE:
2731	case SDEV_EVT_INQUIRY_CHANGE_REPORTED:
2732	case SDEV_EVT_CAPACITY_CHANGE_REPORTED:
2733	case SDEV_EVT_SOFT_THRESHOLD_REACHED_REPORTED:
2734	case SDEV_EVT_MODE_PARAMETER_CHANGE_REPORTED:
2735	case SDEV_EVT_LUN_CHANGE_REPORTED:
2736	case SDEV_EVT_ALUA_STATE_CHANGE_REPORTED:
 
2737	default:
2738		/* do nothing */
2739		break;
2740	}
2741
2742	return evt;
2743}
2744EXPORT_SYMBOL_GPL(sdev_evt_alloc);
2745
2746/**
2747 * 	sdev_evt_send_simple - send asserted event to uevent thread
2748 *	@sdev: scsi_device event occurred on
2749 *	@evt_type: type of event to send
2750 *	@gfpflags: GFP flags for allocation
2751 *
2752 *	Assert scsi device event asynchronously, given an event type.
2753 */
2754void sdev_evt_send_simple(struct scsi_device *sdev,
2755			  enum scsi_device_event evt_type, gfp_t gfpflags)
2756{
2757	struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags);
2758	if (!evt) {
2759		sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n",
2760			    evt_type);
2761		return;
2762	}
2763
2764	sdev_evt_send(sdev, evt);
2765}
2766EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
2767
2768/**
2769 * scsi_request_fn_active() - number of kernel threads inside scsi_request_fn()
2770 * @sdev: SCSI device to count the number of scsi_request_fn() callers for.
2771 */
2772static int scsi_request_fn_active(struct scsi_device *sdev)
2773{
2774	struct request_queue *q = sdev->request_queue;
2775	int request_fn_active;
2776
2777	WARN_ON_ONCE(sdev->host->use_blk_mq);
2778
2779	spin_lock_irq(q->queue_lock);
2780	request_fn_active = q->request_fn_active;
2781	spin_unlock_irq(q->queue_lock);
2782
2783	return request_fn_active;
2784}
2785
2786/**
2787 * scsi_wait_for_queuecommand() - wait for ongoing queuecommand() calls
2788 * @sdev: SCSI device pointer.
2789 *
2790 * Wait until the ongoing shost->hostt->queuecommand() calls that are
2791 * invoked from scsi_request_fn() have finished.
2792 */
2793static void scsi_wait_for_queuecommand(struct scsi_device *sdev)
2794{
2795	WARN_ON_ONCE(sdev->host->use_blk_mq);
2796
2797	while (scsi_request_fn_active(sdev))
2798		msleep(20);
2799}
2800
2801/**
2802 *	scsi_device_quiesce - Block user issued commands.
2803 *	@sdev:	scsi device to quiesce.
2804 *
2805 *	This works by trying to transition to the SDEV_QUIESCE state
2806 *	(which must be a legal transition).  When the device is in this
2807 *	state, only special requests will be accepted, all others will
2808 *	be deferred.  Since special requests may also be requeued requests,
2809 *	a successful return doesn't guarantee the device will be 
2810 *	totally quiescent.
2811 *
2812 *	Must be called with user context, may sleep.
2813 *
2814 *	Returns zero if unsuccessful or an error if not.
2815 */
2816int
2817scsi_device_quiesce(struct scsi_device *sdev)
2818{
2819	int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2820	if (err)
2821		return err;
2822
2823	scsi_run_queue(sdev->request_queue);
2824	while (atomic_read(&sdev->device_busy)) {
2825		msleep_interruptible(200);
2826		scsi_run_queue(sdev->request_queue);
2827	}
2828	return 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2829}
2830EXPORT_SYMBOL(scsi_device_quiesce);
2831
2832/**
2833 *	scsi_device_resume - Restart user issued commands to a quiesced device.
2834 *	@sdev:	scsi device to resume.
2835 *
2836 *	Moves the device from quiesced back to running and restarts the
2837 *	queues.
2838 *
2839 *	Must be called with user context, may sleep.
2840 */
2841void scsi_device_resume(struct scsi_device *sdev)
2842{
2843	/* check if the device state was mutated prior to resume, and if
2844	 * so assume the state is being managed elsewhere (for example
2845	 * device deleted during suspend)
2846	 */
2847	if (sdev->sdev_state != SDEV_QUIESCE ||
2848	    scsi_device_set_state(sdev, SDEV_RUNNING))
2849		return;
2850	scsi_run_queue(sdev->request_queue);
 
 
 
 
2851}
2852EXPORT_SYMBOL(scsi_device_resume);
2853
2854static void
2855device_quiesce_fn(struct scsi_device *sdev, void *data)
2856{
2857	scsi_device_quiesce(sdev);
2858}
2859
2860void
2861scsi_target_quiesce(struct scsi_target *starget)
2862{
2863	starget_for_each_device(starget, NULL, device_quiesce_fn);
2864}
2865EXPORT_SYMBOL(scsi_target_quiesce);
2866
2867static void
2868device_resume_fn(struct scsi_device *sdev, void *data)
2869{
2870	scsi_device_resume(sdev);
2871}
2872
2873void
2874scsi_target_resume(struct scsi_target *starget)
2875{
2876	starget_for_each_device(starget, NULL, device_resume_fn);
2877}
2878EXPORT_SYMBOL(scsi_target_resume);
2879
2880/**
2881 * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state
2882 * @sdev:	device to block
2883 * @wait:	Whether or not to wait until ongoing .queuecommand() /
2884 *		.queue_rq() calls have finished.
2885 *
2886 * Block request made by scsi lld's to temporarily stop all
2887 * scsi commands on the specified device. May sleep.
2888 *
2889 * Returns zero if successful or error if not
2890 *
2891 * Notes:       
2892 *	This routine transitions the device to the SDEV_BLOCK state
2893 *	(which must be a legal transition).  When the device is in this
2894 *	state, all commands are deferred until the scsi lld reenables
2895 *	the device with scsi_device_unblock or device_block_tmo fires.
2896 *
2897 * To do: avoid that scsi_send_eh_cmnd() calls queuecommand() after
2898 * scsi_internal_device_block() has blocked a SCSI device and also
2899 * remove the rport mutex lock and unlock calls from srp_queuecommand().
2900 */
2901int
2902scsi_internal_device_block(struct scsi_device *sdev, bool wait)
2903{
2904	struct request_queue *q = sdev->request_queue;
2905	unsigned long flags;
2906	int err = 0;
2907
2908	err = scsi_device_set_state(sdev, SDEV_BLOCK);
2909	if (err) {
2910		err = scsi_device_set_state(sdev, SDEV_CREATED_BLOCK);
2911
2912		if (err)
2913			return err;
2914	}
2915
2916	/* 
2917	 * The device has transitioned to SDEV_BLOCK.  Stop the
2918	 * block layer from calling the midlayer with this device's
2919	 * request queue. 
2920	 */
2921	if (q->mq_ops) {
2922		if (wait)
2923			blk_mq_quiesce_queue(q);
2924		else
2925			blk_mq_stop_hw_queues(q);
2926	} else {
2927		spin_lock_irqsave(q->queue_lock, flags);
2928		blk_stop_queue(q);
2929		spin_unlock_irqrestore(q->queue_lock, flags);
2930		if (wait)
2931			scsi_wait_for_queuecommand(sdev);
2932	}
2933
2934	return 0;
2935}
2936EXPORT_SYMBOL_GPL(scsi_internal_device_block);
2937 
2938/**
2939 * scsi_internal_device_unblock - resume a device after a block request
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2940 * @sdev:	device to resume
2941 * @new_state:	state to set devices to after unblocking
 
 
 
2942 *
2943 * Called by scsi lld's or the midlayer to restart the device queue
2944 * for the previously suspended scsi device.  Called from interrupt or
2945 * normal process context.
2946 *
2947 * Returns zero if successful or error if not.
2948 *
2949 * Notes:       
2950 *	This routine transitions the device to the SDEV_RUNNING state
2951 *	or to one of the offline states (which must be a legal transition)
2952 *	allowing the midlayer to goose the queue for this device.
2953 */
2954int
2955scsi_internal_device_unblock(struct scsi_device *sdev,
2956			     enum scsi_device_state new_state)
2957{
2958	struct request_queue *q = sdev->request_queue; 
2959	unsigned long flags;
 
 
 
 
 
2960
2961	/*
2962	 * Try to transition the scsi device to SDEV_RUNNING or one of the
2963	 * offlined states and goose the device queue if successful.
2964	 */
2965	if ((sdev->sdev_state == SDEV_BLOCK) ||
2966	    (sdev->sdev_state == SDEV_TRANSPORT_OFFLINE))
 
2967		sdev->sdev_state = new_state;
2968	else if (sdev->sdev_state == SDEV_CREATED_BLOCK) {
 
2969		if (new_state == SDEV_TRANSPORT_OFFLINE ||
2970		    new_state == SDEV_OFFLINE)
2971			sdev->sdev_state = new_state;
2972		else
2973			sdev->sdev_state = SDEV_CREATED;
2974	} else if (sdev->sdev_state != SDEV_CANCEL &&
2975		 sdev->sdev_state != SDEV_OFFLINE)
 
 
 
2976		return -EINVAL;
2977
2978	if (q->mq_ops) {
2979		blk_mq_start_stopped_hw_queues(q, false);
2980	} else {
2981		spin_lock_irqsave(q->queue_lock, flags);
2982		blk_start_queue(q);
2983		spin_unlock_irqrestore(q->queue_lock, flags);
2984	}
 
2985
2986	return 0;
2987}
2988EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2989
2990static void
2991device_block(struct scsi_device *sdev, void *data)
2992{
2993	scsi_internal_device_block(sdev, true);
 
 
 
 
 
2994}
2995
2996static int
2997target_block(struct device *dev, void *data)
2998{
2999	if (scsi_is_target_device(dev))
3000		starget_for_each_device(to_scsi_target(dev), NULL,
3001					device_block);
3002	return 0;
3003}
3004
3005void
3006scsi_target_block(struct device *dev)
3007{
3008	if (scsi_is_target_device(dev))
3009		starget_for_each_device(to_scsi_target(dev), NULL,
3010					device_block);
3011	else
3012		device_for_each_child(dev, NULL, target_block);
3013}
3014EXPORT_SYMBOL_GPL(scsi_target_block);
3015
3016static void
3017device_unblock(struct scsi_device *sdev, void *data)
3018{
3019	scsi_internal_device_unblock(sdev, *(enum scsi_device_state *)data);
3020}
3021
3022static int
3023target_unblock(struct device *dev, void *data)
3024{
3025	if (scsi_is_target_device(dev))
3026		starget_for_each_device(to_scsi_target(dev), data,
3027					device_unblock);
3028	return 0;
3029}
3030
3031void
3032scsi_target_unblock(struct device *dev, enum scsi_device_state new_state)
3033{
3034	if (scsi_is_target_device(dev))
3035		starget_for_each_device(to_scsi_target(dev), &new_state,
3036					device_unblock);
3037	else
3038		device_for_each_child(dev, &new_state, target_unblock);
3039}
3040EXPORT_SYMBOL_GPL(scsi_target_unblock);
3041
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3042/**
3043 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
3044 * @sgl:	scatter-gather list
3045 * @sg_count:	number of segments in sg
3046 * @offset:	offset in bytes into sg, on return offset into the mapped area
3047 * @len:	bytes to map, on return number of bytes mapped
3048 *
3049 * Returns virtual address of the start of the mapped page
3050 */
3051void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
3052			  size_t *offset, size_t *len)
3053{
3054	int i;
3055	size_t sg_len = 0, len_complete = 0;
3056	struct scatterlist *sg;
3057	struct page *page;
3058
3059	WARN_ON(!irqs_disabled());
3060
3061	for_each_sg(sgl, sg, sg_count, i) {
3062		len_complete = sg_len; /* Complete sg-entries */
3063		sg_len += sg->length;
3064		if (sg_len > *offset)
3065			break;
3066	}
3067
3068	if (unlikely(i == sg_count)) {
3069		printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
3070			"elements %d\n",
3071		       __func__, sg_len, *offset, sg_count);
3072		WARN_ON(1);
3073		return NULL;
3074	}
3075
3076	/* Offset starting from the beginning of first page in this sg-entry */
3077	*offset = *offset - len_complete + sg->offset;
3078
3079	/* Assumption: contiguous pages can be accessed as "page + i" */
3080	page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
3081	*offset &= ~PAGE_MASK;
3082
3083	/* Bytes in this sg-entry from *offset to the end of the page */
3084	sg_len = PAGE_SIZE - *offset;
3085	if (*len > sg_len)
3086		*len = sg_len;
3087
3088	return kmap_atomic(page);
3089}
3090EXPORT_SYMBOL(scsi_kmap_atomic_sg);
3091
3092/**
3093 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
3094 * @virt:	virtual address to be unmapped
3095 */
3096void scsi_kunmap_atomic_sg(void *virt)
3097{
3098	kunmap_atomic(virt);
3099}
3100EXPORT_SYMBOL(scsi_kunmap_atomic_sg);
3101
3102void sdev_disable_disk_events(struct scsi_device *sdev)
3103{
3104	atomic_inc(&sdev->disk_events_disable_depth);
3105}
3106EXPORT_SYMBOL(sdev_disable_disk_events);
3107
3108void sdev_enable_disk_events(struct scsi_device *sdev)
3109{
3110	if (WARN_ON_ONCE(atomic_read(&sdev->disk_events_disable_depth) <= 0))
3111		return;
3112	atomic_dec(&sdev->disk_events_disable_depth);
3113}
3114EXPORT_SYMBOL(sdev_enable_disk_events);
3115
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3116/**
3117 * scsi_vpd_lun_id - return a unique device identification
3118 * @sdev: SCSI device
3119 * @id:   buffer for the identification
3120 * @id_len:  length of the buffer
3121 *
3122 * Copies a unique device identification into @id based
3123 * on the information in the VPD page 0x83 of the device.
3124 * The string will be formatted as a SCSI name string.
3125 *
3126 * Returns the length of the identification or error on failure.
3127 * If the identifier is longer than the supplied buffer the actual
3128 * identifier length is returned and the buffer is not zero-padded.
3129 */
3130int scsi_vpd_lun_id(struct scsi_device *sdev, char *id, size_t id_len)
3131{
3132	u8 cur_id_type = 0xff;
3133	u8 cur_id_size = 0;
3134	unsigned char *d, *cur_id_str;
3135	unsigned char __rcu *vpd_pg83;
3136	int id_size = -EINVAL;
3137
3138	rcu_read_lock();
3139	vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
3140	if (!vpd_pg83) {
3141		rcu_read_unlock();
3142		return -ENXIO;
3143	}
3144
3145	/*
3146	 * Look for the correct descriptor.
3147	 * Order of preference for lun descriptor:
3148	 * - SCSI name string
3149	 * - NAA IEEE Registered Extended
3150	 * - EUI-64 based 16-byte
3151	 * - EUI-64 based 12-byte
3152	 * - NAA IEEE Registered
3153	 * - NAA IEEE Extended
3154	 * - T10 Vendor ID
3155	 * as longer descriptors reduce the likelyhood
3156	 * of identification clashes.
3157	 */
3158
3159	/* The id string must be at least 20 bytes + terminating NULL byte */
3160	if (id_len < 21) {
3161		rcu_read_unlock();
3162		return -EINVAL;
3163	}
3164
3165	memset(id, 0, id_len);
3166	d = vpd_pg83 + 4;
3167	while (d < vpd_pg83 + sdev->vpd_pg83_len) {
3168		/* Skip designators not referring to the LUN */
3169		if ((d[1] & 0x30) != 0x00)
3170			goto next_desig;
 
 
3171
3172		switch (d[1] & 0xf) {
3173		case 0x1:
3174			/* T10 Vendor ID */
3175			if (cur_id_size > d[3])
3176				break;
3177			/* Prefer anything */
3178			if (cur_id_type > 0x01 && cur_id_type != 0xff)
3179				break;
3180			cur_id_size = d[3];
3181			if (cur_id_size + 4 > id_len)
3182				cur_id_size = id_len - 4;
3183			cur_id_str = d + 4;
3184			cur_id_type = d[1] & 0xf;
3185			id_size = snprintf(id, id_len, "t10.%*pE",
3186					   cur_id_size, cur_id_str);
3187			break;
3188		case 0x2:
3189			/* EUI-64 */
3190			if (cur_id_size > d[3])
3191				break;
3192			/* Prefer NAA IEEE Registered Extended */
3193			if (cur_id_type == 0x3 &&
3194			    cur_id_size == d[3])
3195				break;
3196			cur_id_size = d[3];
3197			cur_id_str = d + 4;
3198			cur_id_type = d[1] & 0xf;
3199			switch (cur_id_size) {
3200			case 8:
3201				id_size = snprintf(id, id_len,
3202						   "eui.%8phN",
3203						   cur_id_str);
3204				break;
3205			case 12:
3206				id_size = snprintf(id, id_len,
3207						   "eui.%12phN",
3208						   cur_id_str);
3209				break;
3210			case 16:
3211				id_size = snprintf(id, id_len,
3212						   "eui.%16phN",
3213						   cur_id_str);
3214				break;
3215			default:
3216				cur_id_size = 0;
3217				break;
3218			}
3219			break;
3220		case 0x3:
3221			/* NAA */
3222			if (cur_id_size > d[3])
3223				break;
3224			cur_id_size = d[3];
3225			cur_id_str = d + 4;
3226			cur_id_type = d[1] & 0xf;
3227			switch (cur_id_size) {
3228			case 8:
3229				id_size = snprintf(id, id_len,
3230						   "naa.%8phN",
3231						   cur_id_str);
3232				break;
3233			case 16:
3234				id_size = snprintf(id, id_len,
3235						   "naa.%16phN",
3236						   cur_id_str);
3237				break;
3238			default:
3239				cur_id_size = 0;
3240				break;
3241			}
3242			break;
3243		case 0x8:
3244			/* SCSI name string */
3245			if (cur_id_size + 4 > d[3])
3246				break;
3247			/* Prefer others for truncated descriptor */
3248			if (cur_id_size && d[3] > id_len)
3249				break;
 
 
 
 
3250			cur_id_size = id_size = d[3];
3251			cur_id_str = d + 4;
3252			cur_id_type = d[1] & 0xf;
3253			if (cur_id_size >= id_len)
3254				cur_id_size = id_len - 1;
3255			memcpy(id, cur_id_str, cur_id_size);
3256			/* Decrease priority for truncated descriptor */
3257			if (cur_id_size != id_size)
3258				cur_id_size = 6;
3259			break;
3260		default:
3261			break;
3262		}
3263next_desig:
3264		d += d[3] + 4;
3265	}
3266	rcu_read_unlock();
3267
3268	return id_size;
3269}
3270EXPORT_SYMBOL(scsi_vpd_lun_id);
3271
3272/*
3273 * scsi_vpd_tpg_id - return a target port group identifier
3274 * @sdev: SCSI device
3275 *
3276 * Returns the Target Port Group identifier from the information
3277 * froom VPD page 0x83 of the device.
3278 *
3279 * Returns the identifier or error on failure.
3280 */
3281int scsi_vpd_tpg_id(struct scsi_device *sdev, int *rel_id)
3282{
3283	unsigned char *d;
3284	unsigned char __rcu *vpd_pg83;
3285	int group_id = -EAGAIN, rel_port = -1;
3286
3287	rcu_read_lock();
3288	vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
3289	if (!vpd_pg83) {
3290		rcu_read_unlock();
3291		return -ENXIO;
3292	}
3293
3294	d = sdev->vpd_pg83 + 4;
3295	while (d < sdev->vpd_pg83 + sdev->vpd_pg83_len) {
3296		switch (d[1] & 0xf) {
3297		case 0x4:
3298			/* Relative target port */
3299			rel_port = get_unaligned_be16(&d[6]);
3300			break;
3301		case 0x5:
3302			/* Target port group */
3303			group_id = get_unaligned_be16(&d[6]);
3304			break;
3305		default:
3306			break;
3307		}
3308		d += d[3] + 4;
3309	}
3310	rcu_read_unlock();
3311
3312	if (group_id >= 0 && rel_id && rel_port != -1)
3313		*rel_id = rel_port;
3314
3315	return group_id;
3316}
3317EXPORT_SYMBOL(scsi_vpd_tpg_id);