linux/drivers/scsi/scsi_lib.c
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   1/*
   2 *  scsi_lib.c Copyright (C) 1999 Eric Youngdale
   3 *
   4 *  SCSI queueing library.
   5 *      Initial versions: Eric Youngdale (eric@andante.org).
   6 *                        Based upon conversations with large numbers
   7 *                        of people at Linux Expo.
   8 */
   9
  10#include <linux/bio.h>
  11#include <linux/bitops.h>
  12#include <linux/blkdev.h>
  13#include <linux/completion.h>
  14#include <linux/kernel.h>
  15#include <linux/export.h>
  16#include <linux/mempool.h>
  17#include <linux/slab.h>
  18#include <linux/init.h>
  19#include <linux/pci.h>
  20#include <linux/delay.h>
  21#include <linux/hardirq.h>
  22#include <linux/scatterlist.h>
  23
  24#include <scsi/scsi.h>
  25#include <scsi/scsi_cmnd.h>
  26#include <scsi/scsi_dbg.h>
  27#include <scsi/scsi_device.h>
  28#include <scsi/scsi_driver.h>
  29#include <scsi/scsi_eh.h>
  30#include <scsi/scsi_host.h>
  31
  32#include "scsi_priv.h"
  33#include "scsi_logging.h"
  34
  35
  36#define SG_MEMPOOL_NR           ARRAY_SIZE(scsi_sg_pools)
  37#define SG_MEMPOOL_SIZE         2
  38
  39struct scsi_host_sg_pool {
  40        size_t          size;
  41        char            *name;
  42        struct kmem_cache       *slab;
  43        mempool_t       *pool;
  44};
  45
  46#define SP(x) { x, "sgpool-" __stringify(x) }
  47#if (SCSI_MAX_SG_SEGMENTS < 32)
  48#error SCSI_MAX_SG_SEGMENTS is too small (must be 32 or greater)
  49#endif
  50static struct scsi_host_sg_pool scsi_sg_pools[] = {
  51        SP(8),
  52        SP(16),
  53#if (SCSI_MAX_SG_SEGMENTS > 32)
  54        SP(32),
  55#if (SCSI_MAX_SG_SEGMENTS > 64)
  56        SP(64),
  57#if (SCSI_MAX_SG_SEGMENTS > 128)
  58        SP(128),
  59#if (SCSI_MAX_SG_SEGMENTS > 256)
  60#error SCSI_MAX_SG_SEGMENTS is too large (256 MAX)
  61#endif
  62#endif
  63#endif
  64#endif
  65        SP(SCSI_MAX_SG_SEGMENTS)
  66};
  67#undef SP
  68
  69struct kmem_cache *scsi_sdb_cache;
  70
  71#ifdef CONFIG_ACPI
  72#include <acpi/acpi_bus.h>
  73
  74int scsi_register_acpi_bus_type(struct acpi_bus_type *bus)
  75{
  76        bus->bus = &scsi_bus_type;
  77        return register_acpi_bus_type(bus);
  78}
  79EXPORT_SYMBOL_GPL(scsi_register_acpi_bus_type);
  80
  81void scsi_unregister_acpi_bus_type(struct acpi_bus_type *bus)
  82{
  83        unregister_acpi_bus_type(bus);
  84}
  85EXPORT_SYMBOL_GPL(scsi_unregister_acpi_bus_type);
  86#endif
  87
  88/*
  89 * When to reinvoke queueing after a resource shortage. It's 3 msecs to
  90 * not change behaviour from the previous unplug mechanism, experimentation
  91 * may prove this needs changing.
  92 */
  93#define SCSI_QUEUE_DELAY        3
  94
  95/*
  96 * Function:    scsi_unprep_request()
  97 *
  98 * Purpose:     Remove all preparation done for a request, including its
  99 *              associated scsi_cmnd, so that it can be requeued.
 100 *
 101 * Arguments:   req     - request to unprepare
 102 *
 103 * Lock status: Assumed that no locks are held upon entry.
 104 *
 105 * Returns:     Nothing.
 106 */
 107static void scsi_unprep_request(struct request *req)
 108{
 109        struct scsi_cmnd *cmd = req->special;
 110
 111        blk_unprep_request(req);
 112        req->special = NULL;
 113
 114        scsi_put_command(cmd);
 115}
 116
 117/**
 118 * __scsi_queue_insert - private queue insertion
 119 * @cmd: The SCSI command being requeued
 120 * @reason:  The reason for the requeue
 121 * @unbusy: Whether the queue should be unbusied
 122 *
 123 * This is a private queue insertion.  The public interface
 124 * scsi_queue_insert() always assumes the queue should be unbusied
 125 * because it's always called before the completion.  This function is
 126 * for a requeue after completion, which should only occur in this
 127 * file.
 128 */
 129static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy)
 130{
 131        struct Scsi_Host *host = cmd->device->host;
 132        struct scsi_device *device = cmd->device;
 133        struct scsi_target *starget = scsi_target(device);
 134        struct request_queue *q = device->request_queue;
 135        unsigned long flags;
 136
 137        SCSI_LOG_MLQUEUE(1,
 138                 printk("Inserting command %p into mlqueue\n", cmd));
 139
 140        /*
 141         * Set the appropriate busy bit for the device/host.
 142         *
 143         * If the host/device isn't busy, assume that something actually
 144         * completed, and that we should be able to queue a command now.
 145         *
 146         * Note that the prior mid-layer assumption that any host could
 147         * always queue at least one command is now broken.  The mid-layer
 148         * will implement a user specifiable stall (see
 149         * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
 150         * if a command is requeued with no other commands outstanding
 151         * either for the device or for the host.
 152         */
 153        switch (reason) {
 154        case SCSI_MLQUEUE_HOST_BUSY:
 155                host->host_blocked = host->max_host_blocked;
 156                break;
 157        case SCSI_MLQUEUE_DEVICE_BUSY:
 158        case SCSI_MLQUEUE_EH_RETRY:
 159                device->device_blocked = device->max_device_blocked;
 160                break;
 161        case SCSI_MLQUEUE_TARGET_BUSY:
 162                starget->target_blocked = starget->max_target_blocked;
 163                break;
 164        }
 165
 166        /*
 167         * Decrement the counters, since these commands are no longer
 168         * active on the host/device.
 169         */
 170        if (unbusy)
 171                scsi_device_unbusy(device);
 172
 173        /*
 174         * Requeue this command.  It will go before all other commands
 175         * that are already in the queue. Schedule requeue work under
 176         * lock such that the kblockd_schedule_work() call happens
 177         * before blk_cleanup_queue() finishes.
 178         */
 179        spin_lock_irqsave(q->queue_lock, flags);
 180        blk_requeue_request(q, cmd->request);
 181        kblockd_schedule_work(q, &device->requeue_work);
 182        spin_unlock_irqrestore(q->queue_lock, flags);
 183}
 184
 185/*
 186 * Function:    scsi_queue_insert()
 187 *
 188 * Purpose:     Insert a command in the midlevel queue.
 189 *
 190 * Arguments:   cmd    - command that we are adding to queue.
 191 *              reason - why we are inserting command to queue.
 192 *
 193 * Lock status: Assumed that lock is not held upon entry.
 194 *
 195 * Returns:     Nothing.
 196 *
 197 * Notes:       We do this for one of two cases.  Either the host is busy
 198 *              and it cannot accept any more commands for the time being,
 199 *              or the device returned QUEUE_FULL and can accept no more
 200 *              commands.
 201 * Notes:       This could be called either from an interrupt context or a
 202 *              normal process context.
 203 */
 204void scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
 205{
 206        __scsi_queue_insert(cmd, reason, 1);
 207}
 208/**
 209 * scsi_execute - insert request and wait for the result
 210 * @sdev:       scsi device
 211 * @cmd:        scsi command
 212 * @data_direction: data direction
 213 * @buffer:     data buffer
 214 * @bufflen:    len of buffer
 215 * @sense:      optional sense buffer
 216 * @timeout:    request timeout in seconds
 217 * @retries:    number of times to retry request
 218 * @flags:      or into request flags;
 219 * @resid:      optional residual length
 220 *
 221 * returns the req->errors value which is the scsi_cmnd result
 222 * field.
 223 */
 224int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
 225                 int data_direction, void *buffer, unsigned bufflen,
 226                 unsigned char *sense, int timeout, int retries, int flags,
 227                 int *resid)
 228{
 229        struct request *req;
 230        int write = (data_direction == DMA_TO_DEVICE);
 231        int ret = DRIVER_ERROR << 24;
 232
 233        req = blk_get_request(sdev->request_queue, write, __GFP_WAIT);
 234        if (!req)
 235                return ret;
 236
 237        if (bufflen &&  blk_rq_map_kern(sdev->request_queue, req,
 238                                        buffer, bufflen, __GFP_WAIT))
 239                goto out;
 240
 241        req->cmd_len = COMMAND_SIZE(cmd[0]);
 242        memcpy(req->cmd, cmd, req->cmd_len);
 243        req->sense = sense;
 244        req->sense_len = 0;
 245        req->retries = retries;
 246        req->timeout = timeout;
 247        req->cmd_type = REQ_TYPE_BLOCK_PC;
 248        req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT;
 249
 250        /*
 251         * head injection *required* here otherwise quiesce won't work
 252         */
 253        blk_execute_rq(req->q, NULL, req, 1);
 254
 255        /*
 256         * Some devices (USB mass-storage in particular) may transfer
 257         * garbage data together with a residue indicating that the data
 258         * is invalid.  Prevent the garbage from being misinterpreted
 259         * and prevent security leaks by zeroing out the excess data.
 260         */
 261        if (unlikely(req->resid_len > 0 && req->resid_len <= bufflen))
 262                memset(buffer + (bufflen - req->resid_len), 0, req->resid_len);
 263
 264        if (resid)
 265                *resid = req->resid_len;
 266        ret = req->errors;
 267 out:
 268        blk_put_request(req);
 269
 270        return ret;
 271}
 272EXPORT_SYMBOL(scsi_execute);
 273
 274
 275int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
 276                     int data_direction, void *buffer, unsigned bufflen,
 277                     struct scsi_sense_hdr *sshdr, int timeout, int retries,
 278                     int *resid)
 279{
 280        char *sense = NULL;
 281        int result;
 282        
 283        if (sshdr) {
 284                sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
 285                if (!sense)
 286                        return DRIVER_ERROR << 24;
 287        }
 288        result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
 289                              sense, timeout, retries, 0, resid);
 290        if (sshdr)
 291                scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
 292
 293        kfree(sense);
 294        return result;
 295}
 296EXPORT_SYMBOL(scsi_execute_req);
 297
 298/*
 299 * Function:    scsi_init_cmd_errh()
 300 *
 301 * Purpose:     Initialize cmd fields related to error handling.
 302 *
 303 * Arguments:   cmd     - command that is ready to be queued.
 304 *
 305 * Notes:       This function has the job of initializing a number of
 306 *              fields related to error handling.   Typically this will
 307 *              be called once for each command, as required.
 308 */
 309static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
 310{
 311        cmd->serial_number = 0;
 312        scsi_set_resid(cmd, 0);
 313        memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
 314        if (cmd->cmd_len == 0)
 315                cmd->cmd_len = scsi_command_size(cmd->cmnd);
 316}
 317
 318void scsi_device_unbusy(struct scsi_device *sdev)
 319{
 320        struct Scsi_Host *shost = sdev->host;
 321        struct scsi_target *starget = scsi_target(sdev);
 322        unsigned long flags;
 323
 324        spin_lock_irqsave(shost->host_lock, flags);
 325        shost->host_busy--;
 326        starget->target_busy--;
 327        if (unlikely(scsi_host_in_recovery(shost) &&
 328                     (shost->host_failed || shost->host_eh_scheduled)))
 329                scsi_eh_wakeup(shost);
 330        spin_unlock(shost->host_lock);
 331        spin_lock(sdev->request_queue->queue_lock);
 332        sdev->device_busy--;
 333        spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
 334}
 335
 336/*
 337 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
 338 * and call blk_run_queue for all the scsi_devices on the target -
 339 * including current_sdev first.
 340 *
 341 * Called with *no* scsi locks held.
 342 */
 343static void scsi_single_lun_run(struct scsi_device *current_sdev)
 344{
 345        struct Scsi_Host *shost = current_sdev->host;
 346        struct scsi_device *sdev, *tmp;
 347        struct scsi_target *starget = scsi_target(current_sdev);
 348        unsigned long flags;
 349
 350        spin_lock_irqsave(shost->host_lock, flags);
 351        starget->starget_sdev_user = NULL;
 352        spin_unlock_irqrestore(shost->host_lock, flags);
 353
 354        /*
 355         * Call blk_run_queue for all LUNs on the target, starting with
 356         * current_sdev. We race with others (to set starget_sdev_user),
 357         * but in most cases, we will be first. Ideally, each LU on the
 358         * target would get some limited time or requests on the target.
 359         */
 360        blk_run_queue(current_sdev->request_queue);
 361
 362        spin_lock_irqsave(shost->host_lock, flags);
 363        if (starget->starget_sdev_user)
 364                goto out;
 365        list_for_each_entry_safe(sdev, tmp, &starget->devices,
 366                        same_target_siblings) {
 367                if (sdev == current_sdev)
 368                        continue;
 369                if (scsi_device_get(sdev))
 370                        continue;
 371
 372                spin_unlock_irqrestore(shost->host_lock, flags);
 373                blk_run_queue(sdev->request_queue);
 374                spin_lock_irqsave(shost->host_lock, flags);
 375        
 376                scsi_device_put(sdev);
 377        }
 378 out:
 379        spin_unlock_irqrestore(shost->host_lock, flags);
 380}
 381
 382static inline int scsi_device_is_busy(struct scsi_device *sdev)
 383{
 384        if (sdev->device_busy >= sdev->queue_depth || sdev->device_blocked)
 385                return 1;
 386
 387        return 0;
 388}
 389
 390static inline int scsi_target_is_busy(struct scsi_target *starget)
 391{
 392        return ((starget->can_queue > 0 &&
 393                 starget->target_busy >= starget->can_queue) ||
 394                 starget->target_blocked);
 395}
 396
 397static inline int scsi_host_is_busy(struct Scsi_Host *shost)
 398{
 399        if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
 400            shost->host_blocked || shost->host_self_blocked)
 401                return 1;
 402
 403        return 0;
 404}
 405
 406/*
 407 * Function:    scsi_run_queue()
 408 *
 409 * Purpose:     Select a proper request queue to serve next
 410 *
 411 * Arguments:   q       - last request's queue
 412 *
 413 * Returns:     Nothing
 414 *
 415 * Notes:       The previous command was completely finished, start
 416 *              a new one if possible.
 417 */
 418static void scsi_run_queue(struct request_queue *q)
 419{
 420        struct scsi_device *sdev = q->queuedata;
 421        struct Scsi_Host *shost;
 422        LIST_HEAD(starved_list);
 423        unsigned long flags;
 424
 425        shost = sdev->host;
 426        if (scsi_target(sdev)->single_lun)
 427                scsi_single_lun_run(sdev);
 428
 429        spin_lock_irqsave(shost->host_lock, flags);
 430        list_splice_init(&shost->starved_list, &starved_list);
 431
 432        while (!list_empty(&starved_list)) {
 433                /*
 434                 * As long as shost is accepting commands and we have
 435                 * starved queues, call blk_run_queue. scsi_request_fn
 436                 * drops the queue_lock and can add us back to the
 437                 * starved_list.
 438                 *
 439                 * host_lock protects the starved_list and starved_entry.
 440                 * scsi_request_fn must get the host_lock before checking
 441                 * or modifying starved_list or starved_entry.
 442                 */
 443                if (scsi_host_is_busy(shost))
 444                        break;
 445
 446                sdev = list_entry(starved_list.next,
 447                                  struct scsi_device, starved_entry);
 448                list_del_init(&sdev->starved_entry);
 449                if (scsi_target_is_busy(scsi_target(sdev))) {
 450                        list_move_tail(&sdev->starved_entry,
 451                                       &shost->starved_list);
 452                        continue;
 453                }
 454
 455                spin_unlock(shost->host_lock);
 456                spin_lock(sdev->request_queue->queue_lock);
 457                __blk_run_queue(sdev->request_queue);
 458                spin_unlock(sdev->request_queue->queue_lock);
 459                spin_lock(shost->host_lock);
 460        }
 461        /* put any unprocessed entries back */
 462        list_splice(&starved_list, &shost->starved_list);
 463        spin_unlock_irqrestore(shost->host_lock, flags);
 464
 465        blk_run_queue(q);
 466}
 467
 468void scsi_requeue_run_queue(struct work_struct *work)
 469{
 470        struct scsi_device *sdev;
 471        struct request_queue *q;
 472
 473        sdev = container_of(work, struct scsi_device, requeue_work);
 474        q = sdev->request_queue;
 475        scsi_run_queue(q);
 476}
 477
 478/*
 479 * Function:    scsi_requeue_command()
 480 *
 481 * Purpose:     Handle post-processing of completed commands.
 482 *
 483 * Arguments:   q       - queue to operate on
 484 *              cmd     - command that may need to be requeued.
 485 *
 486 * Returns:     Nothing
 487 *
 488 * Notes:       After command completion, there may be blocks left
 489 *              over which weren't finished by the previous command
 490 *              this can be for a number of reasons - the main one is
 491 *              I/O errors in the middle of the request, in which case
 492 *              we need to request the blocks that come after the bad
 493 *              sector.
 494 * Notes:       Upon return, cmd is a stale pointer.
 495 */
 496static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
 497{
 498        struct scsi_device *sdev = cmd->device;
 499        struct request *req = cmd->request;
 500        unsigned long flags;
 501
 502        /*
 503         * We need to hold a reference on the device to avoid the queue being
 504         * killed after the unlock and before scsi_run_queue is invoked which
 505         * may happen because scsi_unprep_request() puts the command which
 506         * releases its reference on the device.
 507         */
 508        get_device(&sdev->sdev_gendev);
 509
 510        spin_lock_irqsave(q->queue_lock, flags);
 511        scsi_unprep_request(req);
 512        blk_requeue_request(q, req);
 513        spin_unlock_irqrestore(q->queue_lock, flags);
 514
 515        scsi_run_queue(q);
 516
 517        put_device(&sdev->sdev_gendev);
 518}
 519
 520void scsi_next_command(struct scsi_cmnd *cmd)
 521{
 522        struct scsi_device *sdev = cmd->device;
 523        struct request_queue *q = sdev->request_queue;
 524
 525        /* need to hold a reference on the device before we let go of the cmd */
 526        get_device(&sdev->sdev_gendev);
 527
 528        scsi_put_command(cmd);
 529        scsi_run_queue(q);
 530
 531        /* ok to remove device now */
 532        put_device(&sdev->sdev_gendev);
 533}
 534
 535void scsi_run_host_queues(struct Scsi_Host *shost)
 536{
 537        struct scsi_device *sdev;
 538
 539        shost_for_each_device(sdev, shost)
 540                scsi_run_queue(sdev->request_queue);
 541}
 542
 543static void __scsi_release_buffers(struct scsi_cmnd *, int);
 544
 545/*
 546 * Function:    scsi_end_request()
 547 *
 548 * Purpose:     Post-processing of completed commands (usually invoked at end
 549 *              of upper level post-processing and scsi_io_completion).
 550 *
 551 * Arguments:   cmd      - command that is complete.
 552 *              error    - 0 if I/O indicates success, < 0 for I/O error.
 553 *              bytes    - number of bytes of completed I/O
 554 *              requeue  - indicates whether we should requeue leftovers.
 555 *
 556 * Lock status: Assumed that lock is not held upon entry.
 557 *
 558 * Returns:     cmd if requeue required, NULL otherwise.
 559 *
 560 * Notes:       This is called for block device requests in order to
 561 *              mark some number of sectors as complete.
 562 * 
 563 *              We are guaranteeing that the request queue will be goosed
 564 *              at some point during this call.
 565 * Notes:       If cmd was requeued, upon return it will be a stale pointer.
 566 */
 567static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error,
 568                                          int bytes, int requeue)
 569{
 570        struct request_queue *q = cmd->device->request_queue;
 571        struct request *req = cmd->request;
 572
 573        /*
 574         * If there are blocks left over at the end, set up the command
 575         * to queue the remainder of them.
 576         */
 577        if (blk_end_request(req, error, bytes)) {
 578                /* kill remainder if no retrys */
 579                if (error && scsi_noretry_cmd(cmd))
 580                        blk_end_request_all(req, error);
 581                else {
 582                        if (requeue) {
 583                                /*
 584                                 * Bleah.  Leftovers again.  Stick the
 585                                 * leftovers in the front of the
 586                                 * queue, and goose the queue again.
 587                                 */
 588                                scsi_release_buffers(cmd);
 589                                scsi_requeue_command(q, cmd);
 590                                cmd = NULL;
 591                        }
 592                        return cmd;
 593                }
 594        }
 595
 596        /*
 597         * This will goose the queue request function at the end, so we don't
 598         * need to worry about launching another command.
 599         */
 600        __scsi_release_buffers(cmd, 0);
 601        scsi_next_command(cmd);
 602        return NULL;
 603}
 604
 605static inline unsigned int scsi_sgtable_index(unsigned short nents)
 606{
 607        unsigned int index;
 608
 609        BUG_ON(nents > SCSI_MAX_SG_SEGMENTS);
 610
 611        if (nents <= 8)
 612                index = 0;
 613        else
 614                index = get_count_order(nents) - 3;
 615
 616        return index;
 617}
 618
 619static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents)
 620{
 621        struct scsi_host_sg_pool *sgp;
 622
 623        sgp = scsi_sg_pools + scsi_sgtable_index(nents);
 624        mempool_free(sgl, sgp->pool);
 625}
 626
 627static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)
 628{
 629        struct scsi_host_sg_pool *sgp;
 630
 631        sgp = scsi_sg_pools + scsi_sgtable_index(nents);
 632        return mempool_alloc(sgp->pool, gfp_mask);
 633}
 634
 635static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents,
 636                              gfp_t gfp_mask)
 637{
 638        int ret;
 639
 640        BUG_ON(!nents);
 641
 642        ret = __sg_alloc_table(&sdb->table, nents, SCSI_MAX_SG_SEGMENTS,
 643                               gfp_mask, scsi_sg_alloc);
 644        if (unlikely(ret))
 645                __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS,
 646                                scsi_sg_free);
 647
 648        return ret;
 649}
 650
 651static void scsi_free_sgtable(struct scsi_data_buffer *sdb)
 652{
 653        __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free);
 654}
 655
 656static void __scsi_release_buffers(struct scsi_cmnd *cmd, int do_bidi_check)
 657{
 658
 659        if (cmd->sdb.table.nents)
 660                scsi_free_sgtable(&cmd->sdb);
 661
 662        memset(&cmd->sdb, 0, sizeof(cmd->sdb));
 663
 664        if (do_bidi_check && scsi_bidi_cmnd(cmd)) {
 665                struct scsi_data_buffer *bidi_sdb =
 666                        cmd->request->next_rq->special;
 667                scsi_free_sgtable(bidi_sdb);
 668                kmem_cache_free(scsi_sdb_cache, bidi_sdb);
 669                cmd->request->next_rq->special = NULL;
 670        }
 671
 672        if (scsi_prot_sg_count(cmd))
 673                scsi_free_sgtable(cmd->prot_sdb);
 674}
 675
 676/*
 677 * Function:    scsi_release_buffers()
 678 *
 679 * Purpose:     Completion processing for block device I/O requests.
 680 *
 681 * Arguments:   cmd     - command that we are bailing.
 682 *
 683 * Lock status: Assumed that no lock is held upon entry.
 684 *
 685 * Returns:     Nothing
 686 *
 687 * Notes:       In the event that an upper level driver rejects a
 688 *              command, we must release resources allocated during
 689 *              the __init_io() function.  Primarily this would involve
 690 *              the scatter-gather table, and potentially any bounce
 691 *              buffers.
 692 */
 693void scsi_release_buffers(struct scsi_cmnd *cmd)
 694{
 695        __scsi_release_buffers(cmd, 1);
 696}
 697EXPORT_SYMBOL(scsi_release_buffers);
 698
 699static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result)
 700{
 701        int error = 0;
 702
 703        switch(host_byte(result)) {
 704        case DID_TRANSPORT_FAILFAST:
 705                error = -ENOLINK;
 706                break;
 707        case DID_TARGET_FAILURE:
 708                set_host_byte(cmd, DID_OK);
 709                error = -EREMOTEIO;
 710                break;
 711        case DID_NEXUS_FAILURE:
 712                set_host_byte(cmd, DID_OK);
 713                error = -EBADE;
 714                break;
 715        default:
 716                error = -EIO;
 717                break;
 718        }
 719
 720        return error;
 721}
 722
 723/*
 724 * Function:    scsi_io_completion()
 725 *
 726 * Purpose:     Completion processing for block device I/O requests.
 727 *
 728 * Arguments:   cmd   - command that is finished.
 729 *
 730 * Lock status: Assumed that no lock is held upon entry.
 731 *
 732 * Returns:     Nothing
 733 *
 734 * Notes:       This function is matched in terms of capabilities to
 735 *              the function that created the scatter-gather list.
 736 *              In other words, if there are no bounce buffers
 737 *              (the normal case for most drivers), we don't need
 738 *              the logic to deal with cleaning up afterwards.
 739 *
 740 *              We must call scsi_end_request().  This will finish off
 741 *              the specified number of sectors.  If we are done, the
 742 *              command block will be released and the queue function
 743 *              will be goosed.  If we are not done then we have to
 744 *              figure out what to do next:
 745 *
 746 *              a) We can call scsi_requeue_command().  The request
 747 *                 will be unprepared and put back on the queue.  Then
 748 *                 a new command will be created for it.  This should
 749 *                 be used if we made forward progress, or if we want
 750 *                 to switch from READ(10) to READ(6) for example.
 751 *
 752 *              b) We can call scsi_queue_insert().  The request will
 753 *                 be put back on the queue and retried using the same
 754 *                 command as before, possibly after a delay.
 755 *
 756 *              c) We can call blk_end_request() with -EIO to fail
 757 *                 the remainder of the request.
 758 */
 759void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 760{
 761        int result = cmd->result;
 762        struct request_queue *q = cmd->device->request_queue;
 763        struct request *req = cmd->request;
 764        int error = 0;
 765        struct scsi_sense_hdr sshdr;
 766        int sense_valid = 0;
 767        int sense_deferred = 0;
 768        enum {ACTION_FAIL, ACTION_REPREP, ACTION_RETRY,
 769              ACTION_DELAYED_RETRY} action;
 770        char *description = NULL;
 771
 772        if (result) {
 773                sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
 774                if (sense_valid)
 775                        sense_deferred = scsi_sense_is_deferred(&sshdr);
 776        }
 777
 778        if (req->cmd_type == REQ_TYPE_BLOCK_PC) { /* SG_IO ioctl from block level */
 779                if (result) {
 780                        if (sense_valid && req->sense) {
 781                                /*
 782                                 * SG_IO wants current and deferred errors
 783                                 */
 784                                int len = 8 + cmd->sense_buffer[7];
 785
 786                                if (len > SCSI_SENSE_BUFFERSIZE)
 787                                        len = SCSI_SENSE_BUFFERSIZE;
 788                                memcpy(req->sense, cmd->sense_buffer,  len);
 789                                req->sense_len = len;
 790                        }
 791                        if (!sense_deferred)
 792                                error = __scsi_error_from_host_byte(cmd, result);
 793                }
 794                /*
 795                 * __scsi_error_from_host_byte may have reset the host_byte
 796                 */
 797                req->errors = cmd->result;
 798
 799                req->resid_len = scsi_get_resid(cmd);
 800
 801                if (scsi_bidi_cmnd(cmd)) {
 802                        /*
 803                         * Bidi commands Must be complete as a whole,
 804                         * both sides at once.
 805                         */
 806                        req->next_rq->resid_len = scsi_in(cmd)->resid;
 807
 808                        scsi_release_buffers(cmd);
 809                        blk_end_request_all(req, 0);
 810
 811                        scsi_next_command(cmd);
 812                        return;
 813                }
 814        }
 815
 816        /* no bidi support for !REQ_TYPE_BLOCK_PC yet */
 817        BUG_ON(blk_bidi_rq(req));
 818
 819        /*
 820         * Next deal with any sectors which we were able to correctly
 821         * handle.
 822         */
 823        SCSI_LOG_HLCOMPLETE(1, printk("%u sectors total, "
 824                                      "%d bytes done.\n",
 825                                      blk_rq_sectors(req), good_bytes));
 826
 827        /*
 828         * Recovered errors need reporting, but they're always treated
 829         * as success, so fiddle the result code here.  For BLOCK_PC
 830         * we already took a copy of the original into rq->errors which
 831         * is what gets returned to the user
 832         */
 833        if (sense_valid && (sshdr.sense_key == RECOVERED_ERROR)) {
 834                /* if ATA PASS-THROUGH INFORMATION AVAILABLE skip
 835                 * print since caller wants ATA registers. Only occurs on
 836                 * SCSI ATA PASS_THROUGH commands when CK_COND=1
 837                 */
 838                if ((sshdr.asc == 0x0) && (sshdr.ascq == 0x1d))
 839                        ;
 840                else if (!(req->cmd_flags & REQ_QUIET))
 841                        scsi_print_sense("", cmd);
 842                result = 0;
 843                /* BLOCK_PC may have set error */
 844                error = 0;
 845        }
 846
 847        /*
 848         * A number of bytes were successfully read.  If there
 849         * are leftovers and there is some kind of error
 850         * (result != 0), retry the rest.
 851         */
 852        if (scsi_end_request(cmd, error, good_bytes, result == 0) == NULL)
 853                return;
 854
 855        error = __scsi_error_from_host_byte(cmd, result);
 856
 857        if (host_byte(result) == DID_RESET) {
 858                /* Third party bus reset or reset for error recovery
 859                 * reasons.  Just retry the command and see what
 860                 * happens.
 861                 */
 862                action = ACTION_RETRY;
 863        } else if (sense_valid && !sense_deferred) {
 864                switch (sshdr.sense_key) {
 865                case UNIT_ATTENTION:
 866                        if (cmd->device->removable) {
 867                                /* Detected disc change.  Set a bit
 868                                 * and quietly refuse further access.
 869                                 */
 870                                cmd->device->changed = 1;
 871                                description = "Media Changed";
 872                                action = ACTION_FAIL;
 873                        } else {
 874                                /* Must have been a power glitch, or a
 875                                 * bus reset.  Could not have been a
 876                                 * media change, so we just retry the
 877                                 * command and see what happens.
 878                                 */
 879                                action = ACTION_RETRY;
 880                        }
 881                        break;
 882                case ILLEGAL_REQUEST:
 883                        /* If we had an ILLEGAL REQUEST returned, then
 884                         * we may have performed an unsupported
 885                         * command.  The only thing this should be
 886                         * would be a ten byte read where only a six
 887                         * byte read was supported.  Also, on a system
 888                         * where READ CAPACITY failed, we may have
 889                         * read past the end of the disk.
 890                         */
 891                        if ((cmd->device->use_10_for_rw &&
 892                            sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
 893                            (cmd->cmnd[0] == READ_10 ||
 894                             cmd->cmnd[0] == WRITE_10)) {
 895                                /* This will issue a new 6-byte command. */
 896                                cmd->device->use_10_for_rw = 0;
 897                                action = ACTION_REPREP;
 898                        } else if (sshdr.asc == 0x10) /* DIX */ {
 899                                description = "Host Data Integrity Failure";
 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                                switch (cmd->cmnd[0]) {
 905                                case UNMAP:
 906                                        description = "Discard failure";
 907                                        break;
 908                                case WRITE_SAME:
 909                                case WRITE_SAME_16:
 910                                        if (cmd->cmnd[1] & 0x8)
 911                                                description = "Discard failure";
 912                                        else
 913                                                description =
 914                                                        "Write same failure";
 915                                        break;
 916                                default:
 917                                        description = "Invalid command failure";
 918                                        break;
 919                                }
 920                                action = ACTION_FAIL;
 921                                error = -EREMOTEIO;
 922                        } else
 923                                action = ACTION_FAIL;
 924                        break;
 925                case ABORTED_COMMAND:
 926                        action = ACTION_FAIL;
 927                        if (sshdr.asc == 0x10) { /* DIF */
 928                                description = "Target Data Integrity Failure";
 929                                error = -EILSEQ;
 930                        }
 931                        break;
 932                case NOT_READY:
 933                        /* If the device is in the process of becoming
 934                         * ready, or has a temporary blockage, retry.
 935                         */
 936                        if (sshdr.asc == 0x04) {
 937                                switch (sshdr.ascq) {
 938                                case 0x01: /* becoming ready */
 939                                case 0x04: /* format in progress */
 940                                case 0x05: /* rebuild in progress */
 941                                case 0x06: /* recalculation in progress */
 942                                case 0x07: /* operation in progress */
 943                                case 0x08: /* Long write in progress */
 944                                case 0x09: /* self test in progress */
 945                                case 0x14: /* space allocation in progress */
 946                                        action = ACTION_DELAYED_RETRY;
 947                                        break;
 948                                default:
 949                                        description = "Device not ready";
 950                                        action = ACTION_FAIL;
 951                                        break;
 952                                }
 953                        } else {
 954                                description = "Device not ready";
 955                                action = ACTION_FAIL;
 956                        }
 957                        break;
 958                case VOLUME_OVERFLOW:
 959                        /* See SSC3rXX or current. */
 960                        action = ACTION_FAIL;
 961                        break;
 962                default:
 963                        description = "Unhandled sense code";
 964                        action = ACTION_FAIL;
 965                        break;
 966                }
 967        } else {
 968                description = "Unhandled error code";
 969                action = ACTION_FAIL;
 970        }
 971
 972        switch (action) {
 973        case ACTION_FAIL:
 974                /* Give up and fail the remainder of the request */
 975                scsi_release_buffers(cmd);
 976                if (!(req->cmd_flags & REQ_QUIET)) {
 977                        if (description)
 978                                scmd_printk(KERN_INFO, cmd, "%s\n",
 979                                            description);
 980                        scsi_print_result(cmd);
 981                        if (driver_byte(result) & DRIVER_SENSE)
 982                                scsi_print_sense("", cmd);
 983                        scsi_print_command(cmd);
 984                }
 985                if (blk_end_request_err(req, error))
 986                        scsi_requeue_command(q, cmd);
 987                else
 988                        scsi_next_command(cmd);
 989                break;
 990        case ACTION_REPREP:
 991                /* Unprep the request and put it back at the head of the queue.
 992                 * A new command will be prepared and issued.
 993                 */
 994                scsi_release_buffers(cmd);
 995                scsi_requeue_command(q, cmd);
 996                break;
 997        case ACTION_RETRY:
 998                /* Retry the same command immediately */
 999                __scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, 0);
1000                break;
1001        case ACTION_DELAYED_RETRY:
1002                /* Retry the same command after a delay */
1003                __scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0);
1004                break;
1005        }
1006}
1007
1008static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
1009                             gfp_t gfp_mask)
1010{
1011        int count;
1012
1013        /*
1014         * If sg table allocation fails, requeue request later.
1015         */
1016        if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments,
1017                                        gfp_mask))) {
1018                return BLKPREP_DEFER;
1019        }
1020
1021        req->buffer = NULL;
1022
1023        /* 
1024         * Next, walk the list, and fill in the addresses and sizes of
1025         * each segment.
1026         */
1027        count = blk_rq_map_sg(req->q, req, sdb->table.sgl);
1028        BUG_ON(count > sdb->table.nents);
1029        sdb->table.nents = count;
1030        sdb->length = blk_rq_bytes(req);
1031        return BLKPREP_OK;
1032}
1033
1034/*
1035 * Function:    scsi_init_io()
1036 *
1037 * Purpose:     SCSI I/O initialize function.
1038 *
1039 * Arguments:   cmd   - Command descriptor we wish to initialize
1040 *
1041 * Returns:     0 on success
1042 *              BLKPREP_DEFER if the failure is retryable
1043 *              BLKPREP_KILL if the failure is fatal
1044 */
1045int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
1046{
1047        struct request *rq = cmd->request;
1048
1049        int error = scsi_init_sgtable(rq, &cmd->sdb, gfp_mask);
1050        if (error)
1051                goto err_exit;
1052
1053        if (blk_bidi_rq(rq)) {
1054                struct scsi_data_buffer *bidi_sdb = kmem_cache_zalloc(
1055                        scsi_sdb_cache, GFP_ATOMIC);
1056                if (!bidi_sdb) {
1057                        error = BLKPREP_DEFER;
1058                        goto err_exit;
1059                }
1060
1061                rq->next_rq->special = bidi_sdb;
1062                error = scsi_init_sgtable(rq->next_rq, bidi_sdb, GFP_ATOMIC);
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                BUG_ON(prot_sdb == NULL);
1072                ivecs = blk_rq_count_integrity_sg(rq->q, rq->bio);
1073
1074                if (scsi_alloc_sgtable(prot_sdb, ivecs, gfp_mask)) {
1075                        error = BLKPREP_DEFER;
1076                        goto err_exit;
1077                }
1078
1079                count = blk_rq_map_integrity_sg(rq->q, rq->bio,
1080                                                prot_sdb->table.sgl);
1081                BUG_ON(unlikely(count > ivecs));
1082                BUG_ON(unlikely(count > queue_max_integrity_segments(rq->q)));
1083
1084                cmd->prot_sdb = prot_sdb;
1085                cmd->prot_sdb->table.nents = count;
1086        }
1087
1088        return BLKPREP_OK ;
1089
1090err_exit:
1091        scsi_release_buffers(cmd);
1092        cmd->request->special = NULL;
1093        scsi_put_command(cmd);
1094        return error;
1095}
1096EXPORT_SYMBOL(scsi_init_io);
1097
1098static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
1099                struct request *req)
1100{
1101        struct scsi_cmnd *cmd;
1102
1103        if (!req->special) {
1104                cmd = scsi_get_command(sdev, GFP_ATOMIC);
1105                if (unlikely(!cmd))
1106                        return NULL;
1107                req->special = cmd;
1108        } else {
1109                cmd = req->special;
1110        }
1111
1112        /* pull a tag out of the request if we have one */
1113        cmd->tag = req->tag;
1114        cmd->request = req;
1115
1116        cmd->cmnd = req->cmd;
1117        cmd->prot_op = SCSI_PROT_NORMAL;
1118
1119        return cmd;
1120}
1121
1122int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
1123{
1124        struct scsi_cmnd *cmd;
1125        int ret = scsi_prep_state_check(sdev, req);
1126
1127        if (ret != BLKPREP_OK)
1128                return ret;
1129
1130        cmd = scsi_get_cmd_from_req(sdev, req);
1131        if (unlikely(!cmd))
1132                return BLKPREP_DEFER;
1133
1134        /*
1135         * BLOCK_PC requests may transfer data, in which case they must
1136         * a bio attached to them.  Or they might contain a SCSI command
1137         * that does not transfer data, in which case they may optionally
1138         * submit a request without an attached bio.
1139         */
1140        if (req->bio) {
1141                int ret;
1142
1143                BUG_ON(!req->nr_phys_segments);
1144
1145                ret = scsi_init_io(cmd, GFP_ATOMIC);
1146                if (unlikely(ret))
1147                        return ret;
1148        } else {
1149                BUG_ON(blk_rq_bytes(req));
1150
1151                memset(&cmd->sdb, 0, sizeof(cmd->sdb));
1152                req->buffer = NULL;
1153        }
1154
1155        cmd->cmd_len = req->cmd_len;
1156        if (!blk_rq_bytes(req))
1157                cmd->sc_data_direction = DMA_NONE;
1158        else if (rq_data_dir(req) == WRITE)
1159                cmd->sc_data_direction = DMA_TO_DEVICE;
1160        else
1161                cmd->sc_data_direction = DMA_FROM_DEVICE;
1162        
1163        cmd->transfersize = blk_rq_bytes(req);
1164        cmd->allowed = req->retries;
1165        return BLKPREP_OK;
1166}
1167EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd);
1168
1169/*
1170 * Setup a REQ_TYPE_FS command.  These are simple read/write request
1171 * from filesystems that still need to be translated to SCSI CDBs from
1172 * the ULD.
1173 */
1174int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
1175{
1176        struct scsi_cmnd *cmd;
1177        int ret = scsi_prep_state_check(sdev, req);
1178
1179        if (ret != BLKPREP_OK)
1180                return ret;
1181
1182        if (unlikely(sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh
1183                         && sdev->scsi_dh_data->scsi_dh->prep_fn)) {
1184                ret = sdev->scsi_dh_data->scsi_dh->prep_fn(sdev, req);
1185                if (ret != BLKPREP_OK)
1186                        return ret;
1187        }
1188
1189        /*
1190         * Filesystem requests must transfer data.
1191         */
1192        BUG_ON(!req->nr_phys_segments);
1193
1194        cmd = scsi_get_cmd_from_req(sdev, req);
1195        if (unlikely(!cmd))
1196                return BLKPREP_DEFER;
1197
1198        memset(cmd->cmnd, 0, BLK_MAX_CDB);
1199        return scsi_init_io(cmd, GFP_ATOMIC);
1200}
1201EXPORT_SYMBOL(scsi_setup_fs_cmnd);
1202
1203int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
1204{
1205        int ret = BLKPREP_OK;
1206
1207        /*
1208         * If the device is not in running state we will reject some
1209         * or all commands.
1210         */
1211        if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1212                switch (sdev->sdev_state) {
1213                case SDEV_OFFLINE:
1214                case SDEV_TRANSPORT_OFFLINE:
1215                        /*
1216                         * If the device is offline we refuse to process any
1217                         * commands.  The device must be brought online
1218                         * before trying any recovery commands.
1219                         */
1220                        sdev_printk(KERN_ERR, sdev,
1221                                    "rejecting I/O to offline device\n");
1222                        ret = BLKPREP_KILL;
1223                        break;
1224                case SDEV_DEL:
1225                        /*
1226                         * If the device is fully deleted, we refuse to
1227                         * process any commands as well.
1228                         */
1229                        sdev_printk(KERN_ERR, sdev,
1230                                    "rejecting I/O to dead device\n");
1231                        ret = BLKPREP_KILL;
1232                        break;
1233                case SDEV_QUIESCE:
1234                case SDEV_BLOCK:
1235                case SDEV_CREATED_BLOCK:
1236                        /*
1237                         * If the devices is blocked we defer normal commands.
1238                         */
1239                        if (!(req->cmd_flags & REQ_PREEMPT))
1240                                ret = BLKPREP_DEFER;
1241                        break;
1242                default:
1243                        /*
1244                         * For any other not fully online state we only allow
1245                         * special commands.  In particular any user initiated
1246                         * command is not allowed.
1247                         */
1248                        if (!(req->cmd_flags & REQ_PREEMPT))
1249                                ret = BLKPREP_KILL;
1250                        break;
1251                }
1252        }
1253        return ret;
1254}
1255EXPORT_SYMBOL(scsi_prep_state_check);
1256
1257int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
1258{
1259        struct scsi_device *sdev = q->queuedata;
1260
1261        switch (ret) {
1262        case BLKPREP_KILL:
1263                req->errors = DID_NO_CONNECT << 16;
1264                /* release the command and kill it */
1265                if (req->special) {
1266                        struct scsi_cmnd *cmd = req->special;
1267                        scsi_release_buffers(cmd);
1268                        scsi_put_command(cmd);
1269                        req->special = NULL;
1270                }
1271                break;
1272        case BLKPREP_DEFER:
1273                /*
1274                 * If we defer, the blk_peek_request() returns NULL, but the
1275                 * queue must be restarted, so we schedule a callback to happen
1276                 * shortly.
1277                 */
1278                if (sdev->device_busy == 0)
1279                        blk_delay_queue(q, SCSI_QUEUE_DELAY);
1280                break;
1281        default:
1282                req->cmd_flags |= REQ_DONTPREP;
1283        }
1284
1285        return ret;
1286}
1287EXPORT_SYMBOL(scsi_prep_return);
1288
1289int scsi_prep_fn(struct request_queue *q, struct request *req)
1290{
1291        struct scsi_device *sdev = q->queuedata;
1292        int ret = BLKPREP_KILL;
1293
1294        if (req->cmd_type == REQ_TYPE_BLOCK_PC)
1295                ret = scsi_setup_blk_pc_cmnd(sdev, req);
1296        return scsi_prep_return(q, req, ret);
1297}
1298EXPORT_SYMBOL(scsi_prep_fn);
1299
1300/*
1301 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1302 * return 0.
1303 *
1304 * Called with the queue_lock held.
1305 */
1306static inline int scsi_dev_queue_ready(struct request_queue *q,
1307                                  struct scsi_device *sdev)
1308{
1309        if (sdev->device_busy == 0 && sdev->device_blocked) {
1310                /*
1311                 * unblock after device_blocked iterates to zero
1312                 */
1313                if (--sdev->device_blocked == 0) {
1314                        SCSI_LOG_MLQUEUE(3,
1315                                   sdev_printk(KERN_INFO, sdev,
1316                                   "unblocking device at zero depth\n"));
1317                } else {
1318                        blk_delay_queue(q, SCSI_QUEUE_DELAY);
1319                        return 0;
1320                }
1321        }
1322        if (scsi_device_is_busy(sdev))
1323                return 0;
1324
1325        return 1;
1326}
1327
1328
1329/*
1330 * scsi_target_queue_ready: checks if there we can send commands to target
1331 * @sdev: scsi device on starget to check.
1332 *
1333 * Called with the host lock held.
1334 */
1335static inline int scsi_target_queue_ready(struct Scsi_Host *shost,
1336                                           struct scsi_device *sdev)
1337{
1338        struct scsi_target *starget = scsi_target(sdev);
1339
1340        if (starget->single_lun) {
1341                if (starget->starget_sdev_user &&
1342                    starget->starget_sdev_user != sdev)
1343                        return 0;
1344                starget->starget_sdev_user = sdev;
1345        }
1346
1347        if (starget->target_busy == 0 && starget->target_blocked) {
1348                /*
1349                 * unblock after target_blocked iterates to zero
1350                 */
1351                if (--starget->target_blocked == 0) {
1352                        SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget,
1353                                         "unblocking target at zero depth\n"));
1354                } else
1355                        return 0;
1356        }
1357
1358        if (scsi_target_is_busy(starget)) {
1359                list_move_tail(&sdev->starved_entry, &shost->starved_list);
1360                return 0;
1361        }
1362
1363        return 1;
1364}
1365
1366/*
1367 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1368 * return 0. We must end up running the queue again whenever 0 is
1369 * returned, else IO can hang.
1370 *
1371 * Called with host_lock held.
1372 */
1373static inline int scsi_host_queue_ready(struct request_queue *q,
1374                                   struct Scsi_Host *shost,
1375                                   struct scsi_device *sdev)
1376{
1377        if (scsi_host_in_recovery(shost))
1378                return 0;
1379        if (shost->host_busy == 0 && shost->host_blocked) {
1380                /*
1381                 * unblock after host_blocked iterates to zero
1382                 */
1383                if (--shost->host_blocked == 0) {
1384                        SCSI_LOG_MLQUEUE(3,
1385                                printk("scsi%d unblocking host at zero depth\n",
1386                                        shost->host_no));
1387                } else {
1388                        return 0;
1389                }
1390        }
1391        if (scsi_host_is_busy(shost)) {
1392                if (list_empty(&sdev->starved_entry))
1393                        list_add_tail(&sdev->starved_entry, &shost->starved_list);
1394                return 0;
1395        }
1396
1397        /* We're OK to process the command, so we can't be starved */
1398        if (!list_empty(&sdev->starved_entry))
1399                list_del_init(&sdev->starved_entry);
1400
1401        return 1;
1402}
1403
1404/*
1405 * Busy state exporting function for request stacking drivers.
1406 *
1407 * For efficiency, no lock is taken to check the busy state of
1408 * shost/starget/sdev, since the returned value is not guaranteed and
1409 * may be changed after request stacking drivers call the function,
1410 * regardless of taking lock or not.
1411 *
1412 * When scsi can't dispatch I/Os anymore and needs to kill I/Os scsi
1413 * needs to return 'not busy'. Otherwise, request stacking drivers
1414 * may hold requests forever.
1415 */
1416static int scsi_lld_busy(struct request_queue *q)
1417{
1418        struct scsi_device *sdev = q->queuedata;
1419        struct Scsi_Host *shost;
1420
1421        if (blk_queue_dying(q))
1422                return 0;
1423
1424        shost = sdev->host;
1425
1426        /*
1427         * Ignore host/starget busy state.
1428         * Since block layer does not have a concept of fairness across
1429         * multiple queues, congestion of host/starget needs to be handled
1430         * in SCSI layer.
1431         */
1432        if (scsi_host_in_recovery(shost) || scsi_device_is_busy(sdev))
1433                return 1;
1434
1435        return 0;
1436}
1437
1438/*
1439 * Kill a request for a dead device
1440 */
1441static void scsi_kill_request(struct request *req, struct request_queue *q)
1442{
1443        struct scsi_cmnd *cmd = req->special;
1444        struct scsi_device *sdev;
1445        struct scsi_target *starget;
1446        struct Scsi_Host *shost;
1447
1448        blk_start_request(req);
1449
1450        scmd_printk(KERN_INFO, cmd, "killing request\n");
1451
1452        sdev = cmd->device;
1453        starget = scsi_target(sdev);
1454        shost = sdev->host;
1455        scsi_init_cmd_errh(cmd);
1456        cmd->result = DID_NO_CONNECT << 16;
1457        atomic_inc(&cmd->device->iorequest_cnt);
1458
1459        /*
1460         * SCSI request completion path will do scsi_device_unbusy(),
1461         * bump busy counts.  To bump the counters, we need to dance
1462         * with the locks as normal issue path does.
1463         */
1464        sdev->device_busy++;
1465        spin_unlock(sdev->request_queue->queue_lock);
1466        spin_lock(shost->host_lock);
1467        shost->host_busy++;
1468        starget->target_busy++;
1469        spin_unlock(shost->host_lock);
1470        spin_lock(sdev->request_queue->queue_lock);
1471
1472        blk_complete_request(req);
1473}
1474
1475static void scsi_softirq_done(struct request *rq)
1476{
1477        struct scsi_cmnd *cmd = rq->special;
1478        unsigned long wait_for = (cmd->allowed + 1) * rq->timeout;
1479        int disposition;
1480
1481        INIT_LIST_HEAD(&cmd->eh_entry);
1482
1483        atomic_inc(&cmd->device->iodone_cnt);
1484        if (cmd->result)
1485                atomic_inc(&cmd->device->ioerr_cnt);
1486
1487        disposition = scsi_decide_disposition(cmd);
1488        if (disposition != SUCCESS &&
1489            time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
1490                sdev_printk(KERN_ERR, cmd->device,
1491                            "timing out command, waited %lus\n",
1492                            wait_for/HZ);
1493                disposition = SUCCESS;
1494        }
1495                        
1496        scsi_log_completion(cmd, disposition);
1497
1498        switch (disposition) {
1499                case SUCCESS:
1500                        scsi_finish_command(cmd);
1501                        break;
1502                case NEEDS_RETRY:
1503                        scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
1504                        break;
1505                case ADD_TO_MLQUEUE:
1506                        scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1507                        break;
1508                default:
1509                        if (!scsi_eh_scmd_add(cmd, 0))
1510                                scsi_finish_command(cmd);
1511        }
1512}
1513
1514/*
1515 * Function:    scsi_request_fn()
1516 *
1517 * Purpose:     Main strategy routine for SCSI.
1518 *
1519 * Arguments:   q       - Pointer to actual queue.
1520 *
1521 * Returns:     Nothing
1522 *
1523 * Lock status: IO request lock assumed to be held when called.
1524 */
1525static void scsi_request_fn(struct request_queue *q)
1526{
1527        struct scsi_device *sdev = q->queuedata;
1528        struct Scsi_Host *shost;
1529        struct scsi_cmnd *cmd;
1530        struct request *req;
1531
1532        if(!get_device(&sdev->sdev_gendev))
1533                /* We must be tearing the block queue down already */
1534                return;
1535
1536        /*
1537         * To start with, we keep looping until the queue is empty, or until
1538         * the host is no longer able to accept any more requests.
1539         */
1540        shost = sdev->host;
1541        for (;;) {
1542                int rtn;
1543                /*
1544                 * get next queueable request.  We do this early to make sure
1545                 * that the request is fully prepared even if we cannot 
1546                 * accept it.
1547                 */
1548                req = blk_peek_request(q);
1549                if (!req || !scsi_dev_queue_ready(q, sdev))
1550                        break;
1551
1552                if (unlikely(!scsi_device_online(sdev))) {
1553                        sdev_printk(KERN_ERR, sdev,
1554                                    "rejecting I/O to offline device\n");
1555                        scsi_kill_request(req, q);
1556                        continue;
1557                }
1558
1559
1560                /*
1561                 * Remove the request from the request list.
1562                 */
1563                if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1564                        blk_start_request(req);
1565                sdev->device_busy++;
1566
1567                spin_unlock(q->queue_lock);
1568                cmd = req->special;
1569                if (unlikely(cmd == NULL)) {
1570                        printk(KERN_CRIT "impossible request in %s.\n"
1571                                         "please mail a stack trace to "
1572                                         "linux-scsi@vger.kernel.org\n",
1573                                         __func__);
1574                        blk_dump_rq_flags(req, "foo");
1575                        BUG();
1576                }
1577                spin_lock(shost->host_lock);
1578
1579                /*
1580                 * We hit this when the driver is using a host wide
1581                 * tag map. For device level tag maps the queue_depth check
1582                 * in the device ready fn would prevent us from trying
1583                 * to allocate a tag. Since the map is a shared host resource
1584                 * we add the dev to the starved list so it eventually gets
1585                 * a run when a tag is freed.
1586                 */
1587                if (blk_queue_tagged(q) && !blk_rq_tagged(req)) {
1588                        if (list_empty(&sdev->starved_entry))
1589                                list_add_tail(&sdev->starved_entry,
1590                                              &shost->starved_list);
1591                        goto not_ready;
1592                }
1593
1594                if (!scsi_target_queue_ready(shost, sdev))
1595                        goto not_ready;
1596
1597                if (!scsi_host_queue_ready(q, shost, sdev))
1598                        goto not_ready;
1599
1600                scsi_target(sdev)->target_busy++;
1601                shost->host_busy++;
1602
1603                /*
1604                 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1605                 *              take the lock again.
1606                 */
1607                spin_unlock_irq(shost->host_lock);
1608
1609                /*
1610                 * Finally, initialize any error handling parameters, and set up
1611                 * the timers for timeouts.
1612                 */
1613                scsi_init_cmd_errh(cmd);
1614
1615                /*
1616                 * Dispatch the command to the low-level driver.
1617                 */
1618                rtn = scsi_dispatch_cmd(cmd);
1619                spin_lock_irq(q->queue_lock);
1620                if (rtn)
1621                        goto out_delay;
1622        }
1623
1624        goto out;
1625
1626 not_ready:
1627        spin_unlock_irq(shost->host_lock);
1628
1629        /*
1630         * lock q, handle tag, requeue req, and decrement device_busy. We
1631         * must return with queue_lock held.
1632         *
1633         * Decrementing device_busy without checking it is OK, as all such
1634         * cases (host limits or settings) should run the queue at some
1635         * later time.
1636         */
1637        spin_lock_irq(q->queue_lock);
1638        blk_requeue_request(q, req);
1639        sdev->device_busy--;
1640out_delay:
1641        if (sdev->device_busy == 0)
1642                blk_delay_queue(q, SCSI_QUEUE_DELAY);
1643out:
1644        /* must be careful here...if we trigger the ->remove() function
1645         * we cannot be holding the q lock */
1646        spin_unlock_irq(q->queue_lock);
1647        put_device(&sdev->sdev_gendev);
1648        spin_lock_irq(q->queue_lock);
1649}
1650
1651u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1652{
1653        struct device *host_dev;
1654        u64 bounce_limit = 0xffffffff;
1655
1656        if (shost->unchecked_isa_dma)
1657                return BLK_BOUNCE_ISA;
1658        /*
1659         * Platforms with virtual-DMA translation
1660         * hardware have no practical limit.
1661         */
1662        if (!PCI_DMA_BUS_IS_PHYS)
1663                return BLK_BOUNCE_ANY;
1664
1665        host_dev = scsi_get_device(shost);
1666        if (host_dev && host_dev->dma_mask)
1667                bounce_limit = *host_dev->dma_mask;
1668
1669        return bounce_limit;
1670}
1671EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1672
1673struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
1674                                         request_fn_proc *request_fn)
1675{
1676        struct request_queue *q;
1677        struct device *dev = shost->dma_dev;
1678
1679        q = blk_init_queue(request_fn, NULL);
1680        if (!q)
1681                return NULL;
1682
1683        /*
1684         * this limit is imposed by hardware restrictions
1685         */
1686        blk_queue_max_segments(q, min_t(unsigned short, shost->sg_tablesize,
1687                                        SCSI_MAX_SG_CHAIN_SEGMENTS));
1688
1689        if (scsi_host_prot_dma(shost)) {
1690                shost->sg_prot_tablesize =
1691                        min_not_zero(shost->sg_prot_tablesize,
1692                                     (unsigned short)SCSI_MAX_PROT_SG_SEGMENTS);
1693                BUG_ON(shost->sg_prot_tablesize < shost->sg_tablesize);
1694                blk_queue_max_integrity_segments(q, shost->sg_prot_tablesize);
1695        }
1696
1697        blk_queue_max_hw_sectors(q, shost->max_sectors);
1698        blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1699        blk_queue_segment_boundary(q, shost->dma_boundary);
1700        dma_set_seg_boundary(dev, shost->dma_boundary);
1701
1702        blk_queue_max_segment_size(q, dma_get_max_seg_size(dev));
1703
1704        if (!shost->use_clustering)
1705                q->limits.cluster = 0;
1706
1707        /*
1708         * set a reasonable default alignment on word boundaries: the
1709         * host and device may alter it using
1710         * blk_queue_update_dma_alignment() later.
1711         */
1712        blk_queue_dma_alignment(q, 0x03);
1713
1714        return q;
1715}
1716EXPORT_SYMBOL(__scsi_alloc_queue);
1717
1718struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1719{
1720        struct request_queue *q;
1721
1722        q = __scsi_alloc_queue(sdev->host, scsi_request_fn);
1723        if (!q)
1724                return NULL;
1725
1726        blk_queue_prep_rq(q, scsi_prep_fn);
1727        blk_queue_softirq_done(q, scsi_softirq_done);
1728        blk_queue_rq_timed_out(q, scsi_times_out);
1729        blk_queue_lld_busy(q, scsi_lld_busy);
1730        return q;
1731}
1732
1733/*
1734 * Function:    scsi_block_requests()
1735 *
1736 * Purpose:     Utility function used by low-level drivers to prevent further
1737 *              commands from being queued to the device.
1738 *
1739 * Arguments:   shost       - Host in question
1740 *
1741 * Returns:     Nothing
1742 *
1743 * Lock status: No locks are assumed held.
1744 *
1745 * Notes:       There is no timer nor any other means by which the requests
1746 *              get unblocked other than the low-level driver calling
1747 *              scsi_unblock_requests().
1748 */
1749void scsi_block_requests(struct Scsi_Host *shost)
1750{
1751        shost->host_self_blocked = 1;
1752}
1753EXPORT_SYMBOL(scsi_block_requests);
1754
1755/*
1756 * Function:    scsi_unblock_requests()
1757 *
1758 * Purpose:     Utility function used by low-level drivers to allow further
1759 *              commands from being queued to the device.
1760 *
1761 * Arguments:   shost       - Host in question
1762 *
1763 * Returns:     Nothing
1764 *
1765 * Lock status: No locks are assumed held.
1766 *
1767 * Notes:       There is no timer nor any other means by which the requests
1768 *              get unblocked other than the low-level driver calling
1769 *              scsi_unblock_requests().
1770 *
1771 *              This is done as an API function so that changes to the
1772 *              internals of the scsi mid-layer won't require wholesale
1773 *              changes to drivers that use this feature.
1774 */
1775void scsi_unblock_requests(struct Scsi_Host *shost)
1776{
1777        shost->host_self_blocked = 0;
1778        scsi_run_host_queues(shost);
1779}
1780EXPORT_SYMBOL(scsi_unblock_requests);
1781
1782int __init scsi_init_queue(void)
1783{
1784        int i;
1785
1786        scsi_sdb_cache = kmem_cache_create("scsi_data_buffer",
1787                                           sizeof(struct scsi_data_buffer),
1788                                           0, 0, NULL);
1789        if (!scsi_sdb_cache) {
1790                printk(KERN_ERR "SCSI: can't init scsi sdb cache\n");
1791                return -ENOMEM;
1792        }
1793
1794        for (i = 0; i < SG_MEMPOOL_NR; i++) {
1795                struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1796                int size = sgp->size * sizeof(struct scatterlist);
1797
1798                sgp->slab = kmem_cache_create(sgp->name, size, 0,
1799                                SLAB_HWCACHE_ALIGN, NULL);
1800                if (!sgp->slab) {
1801                        printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1802                                        sgp->name);
1803                        goto cleanup_sdb;
1804                }
1805
1806                sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
1807                                                     sgp->slab);
1808                if (!sgp->pool) {
1809                        printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1810                                        sgp->name);
1811                        goto cleanup_sdb;
1812                }
1813        }
1814
1815        return 0;
1816
1817cleanup_sdb:
1818        for (i = 0; i < SG_MEMPOOL_NR; i++) {
1819                struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1820                if (sgp->pool)
1821                        mempool_destroy(sgp->pool);
1822                if (sgp->slab)
1823                        kmem_cache_destroy(sgp->slab);
1824        }
1825        kmem_cache_destroy(scsi_sdb_cache);
1826
1827        return -ENOMEM;
1828}
1829
1830void scsi_exit_queue(void)
1831{
1832        int i;
1833
1834        kmem_cache_destroy(scsi_sdb_cache);
1835
1836        for (i = 0; i < SG_MEMPOOL_NR; i++) {
1837                struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1838                mempool_destroy(sgp->pool);
1839                kmem_cache_destroy(sgp->slab);
1840        }
1841}
1842
1843/**
1844 *      scsi_mode_select - issue a mode select
1845 *      @sdev:  SCSI device to be queried
1846 *      @pf:    Page format bit (1 == standard, 0 == vendor specific)
1847 *      @sp:    Save page bit (0 == don't save, 1 == save)
1848 *      @modepage: mode page being requested
1849 *      @buffer: request buffer (may not be smaller than eight bytes)
1850 *      @len:   length of request buffer.
1851 *      @timeout: command timeout
1852 *      @retries: number of retries before failing
1853 *      @data: returns a structure abstracting the mode header data
1854 *      @sshdr: place to put sense data (or NULL if no sense to be collected).
1855 *              must be SCSI_SENSE_BUFFERSIZE big.
1856 *
1857 *      Returns zero if successful; negative error number or scsi
1858 *      status on error
1859 *
1860 */
1861int
1862scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
1863                 unsigned char *buffer, int len, int timeout, int retries,
1864                 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1865{
1866        unsigned char cmd[10];
1867        unsigned char *real_buffer;
1868        int ret;
1869
1870        memset(cmd, 0, sizeof(cmd));
1871        cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
1872
1873        if (sdev->use_10_for_ms) {
1874                if (len > 65535)
1875                        return -EINVAL;
1876                real_buffer = kmalloc(8 + len, GFP_KERNEL);
1877                if (!real_buffer)
1878                        return -ENOMEM;
1879                memcpy(real_buffer + 8, buffer, len);
1880                len += 8;
1881                real_buffer[0] = 0;
1882                real_buffer[1] = 0;
1883                real_buffer[2] = data->medium_type;
1884                real_buffer[3] = data->device_specific;
1885                real_buffer[4] = data->longlba ? 0x01 : 0;
1886                real_buffer[5] = 0;
1887                real_buffer[6] = data->block_descriptor_length >> 8;
1888                real_buffer[7] = data->block_descriptor_length;
1889
1890                cmd[0] = MODE_SELECT_10;
1891                cmd[7] = len >> 8;
1892                cmd[8] = len;
1893        } else {
1894                if (len > 255 || data->block_descriptor_length > 255 ||
1895                    data->longlba)
1896                        return -EINVAL;
1897
1898                real_buffer = kmalloc(4 + len, GFP_KERNEL);
1899                if (!real_buffer)
1900                        return -ENOMEM;
1901                memcpy(real_buffer + 4, buffer, len);
1902                len += 4;
1903                real_buffer[0] = 0;
1904                real_buffer[1] = data->medium_type;
1905                real_buffer[2] = data->device_specific;
1906                real_buffer[3] = data->block_descriptor_length;
1907                
1908
1909                cmd[0] = MODE_SELECT;
1910                cmd[4] = len;
1911        }
1912
1913        ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
1914                               sshdr, timeout, retries, NULL);
1915        kfree(real_buffer);
1916        return ret;
1917}
1918EXPORT_SYMBOL_GPL(scsi_mode_select);
1919
1920/**
1921 *      scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
1922 *      @sdev:  SCSI device to be queried
1923 *      @dbd:   set if mode sense will allow block descriptors to be returned
1924 *      @modepage: mode page being requested
1925 *      @buffer: request buffer (may not be smaller than eight bytes)
1926 *      @len:   length of request buffer.
1927 *      @timeout: command timeout
1928 *      @retries: number of retries before failing
1929 *      @data: returns a structure abstracting the mode header data
1930 *      @sshdr: place to put sense data (or NULL if no sense to be collected).
1931 *              must be SCSI_SENSE_BUFFERSIZE big.
1932 *
1933 *      Returns zero if unsuccessful, or the header offset (either 4
1934 *      or 8 depending on whether a six or ten byte command was
1935 *      issued) if successful.
1936 */
1937int
1938scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
1939                  unsigned char *buffer, int len, int timeout, int retries,
1940                  struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1941{
1942        unsigned char cmd[12];
1943        int use_10_for_ms;
1944        int header_length;
1945        int result;
1946        struct scsi_sense_hdr my_sshdr;
1947
1948        memset(data, 0, sizeof(*data));
1949        memset(&cmd[0], 0, 12);
1950        cmd[1] = dbd & 0x18;    /* allows DBD and LLBA bits */
1951        cmd[2] = modepage;
1952
1953        /* caller might not be interested in sense, but we need it */
1954        if (!sshdr)
1955                sshdr = &my_sshdr;
1956
1957 retry:
1958        use_10_for_ms = sdev->use_10_for_ms;
1959
1960        if (use_10_for_ms) {
1961                if (len < 8)
1962                        len = 8;
1963
1964                cmd[0] = MODE_SENSE_10;
1965                cmd[8] = len;
1966                header_length = 8;
1967        } else {
1968                if (len < 4)
1969                        len = 4;
1970
1971                cmd[0] = MODE_SENSE;
1972                cmd[4] = len;
1973                header_length = 4;
1974        }
1975
1976        memset(buffer, 0, len);
1977
1978        result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
1979                                  sshdr, timeout, retries, NULL);
1980
1981        /* This code looks awful: what it's doing is making sure an
1982         * ILLEGAL REQUEST sense return identifies the actual command
1983         * byte as the problem.  MODE_SENSE commands can return
1984         * ILLEGAL REQUEST if the code page isn't supported */
1985
1986        if (use_10_for_ms && !scsi_status_is_good(result) &&
1987            (driver_byte(result) & DRIVER_SENSE)) {
1988                if (scsi_sense_valid(sshdr)) {
1989                        if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
1990                            (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
1991                                /* 
1992                                 * Invalid command operation code
1993                                 */
1994                                sdev->use_10_for_ms = 0;
1995                                goto retry;
1996                        }
1997                }
1998        }
1999
2000        if(scsi_status_is_good(result)) {
2001                if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
2002                             (modepage == 6 || modepage == 8))) {
2003                        /* Initio breakage? */
2004                        header_length = 0;
2005                        data->length = 13;
2006                        data->medium_type = 0;
2007                        data->device_specific = 0;
2008                        data->longlba = 0;
2009                        data->block_descriptor_length = 0;
2010                } else if(use_10_for_ms) {
2011                        data->length = buffer[0]*256 + buffer[1] + 2;
2012                        data->medium_type = buffer[2];
2013                        data->device_specific = buffer[3];
2014                        data->longlba = buffer[4] & 0x01;
2015                        data->block_descriptor_length = buffer[6]*256
2016                                + buffer[7];
2017                } else {
2018                        data->length = buffer[0] + 1;
2019                        data->medium_type = buffer[1];
2020                        data->device_specific = buffer[2];
2021                        data->block_descriptor_length = buffer[3];
2022                }
2023                data->header_length = header_length;
2024        }
2025
2026        return result;
2027}
2028EXPORT_SYMBOL(scsi_mode_sense);
2029
2030/**
2031 *      scsi_test_unit_ready - test if unit is ready
2032 *      @sdev:  scsi device to change the state of.
2033 *      @timeout: command timeout
2034 *      @retries: number of retries before failing
2035 *      @sshdr_external: Optional pointer to struct scsi_sense_hdr for
2036 *              returning sense. Make sure that this is cleared before passing
2037 *              in.
2038 *
2039 *      Returns zero if unsuccessful or an error if TUR failed.  For
2040 *      removable media, UNIT_ATTENTION sets ->changed flag.
2041 **/
2042int
2043scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
2044                     struct scsi_sense_hdr *sshdr_external)
2045{
2046        char cmd[] = {
2047                TEST_UNIT_READY, 0, 0, 0, 0, 0,
2048        };
2049        struct scsi_sense_hdr *sshdr;
2050        int result;
2051
2052        if (!sshdr_external)
2053                sshdr = kzalloc(sizeof(*sshdr), GFP_KERNEL);
2054        else
2055                sshdr = sshdr_external;
2056
2057        /* try to eat the UNIT_ATTENTION if there are enough retries */
2058        do {
2059                result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
2060                                          timeout, retries, NULL);
2061                if (sdev->removable && scsi_sense_valid(sshdr) &&
2062                    sshdr->sense_key == UNIT_ATTENTION)
2063                        sdev->changed = 1;
2064        } while (scsi_sense_valid(sshdr) &&
2065                 sshdr->sense_key == UNIT_ATTENTION && --retries);
2066
2067        if (!sshdr_external)
2068                kfree(sshdr);
2069        return result;
2070}
2071EXPORT_SYMBOL(scsi_test_unit_ready);
2072
2073/**
2074 *      scsi_device_set_state - Take the given device through the device state model.
2075 *      @sdev:  scsi device to change the state of.
2076 *      @state: state to change to.
2077 *
2078 *      Returns zero if unsuccessful or an error if the requested 
2079 *      transition is illegal.
2080 */
2081int
2082scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
2083{
2084        enum scsi_device_state oldstate = sdev->sdev_state;
2085
2086        if (state == oldstate)
2087                return 0;
2088
2089        switch (state) {
2090        case SDEV_CREATED:
2091                switch (oldstate) {
2092                case SDEV_CREATED_BLOCK:
2093                        break;
2094                default:
2095                        goto illegal;
2096                }
2097                break;
2098                        
2099        case SDEV_RUNNING:
2100                switch (oldstate) {
2101                case SDEV_CREATED:
2102                case SDEV_OFFLINE:
2103                case SDEV_TRANSPORT_OFFLINE:
2104                case SDEV_QUIESCE:
2105                case SDEV_BLOCK:
2106                        break;
2107                default:
2108                        goto illegal;
2109                }
2110                break;
2111
2112        case SDEV_QUIESCE:
2113                switch (oldstate) {
2114                case SDEV_RUNNING:
2115                case SDEV_OFFLINE:
2116                case SDEV_TRANSPORT_OFFLINE:
2117                        break;
2118                default:
2119                        goto illegal;
2120                }
2121                break;
2122
2123        case SDEV_OFFLINE:
2124        case SDEV_TRANSPORT_OFFLINE:
2125                switch (oldstate) {
2126                case SDEV_CREATED:
2127                case SDEV_RUNNING:
2128                case SDEV_QUIESCE:
2129                case SDEV_BLOCK:
2130                        break;
2131                default:
2132                        goto illegal;
2133                }
2134                break;
2135
2136        case SDEV_BLOCK:
2137                switch (oldstate) {
2138                case SDEV_RUNNING:
2139                case SDEV_CREATED_BLOCK:
2140                        break;
2141                default:
2142                        goto illegal;
2143                }
2144                break;
2145
2146        case SDEV_CREATED_BLOCK:
2147                switch (oldstate) {
2148                case SDEV_CREATED:
2149                        break;
2150                default:
2151                        goto illegal;
2152                }
2153                break;
2154
2155        case SDEV_CANCEL:
2156                switch (oldstate) {
2157                case SDEV_CREATED:
2158                case SDEV_RUNNING:
2159                case SDEV_QUIESCE:
2160                case SDEV_OFFLINE:
2161                case SDEV_TRANSPORT_OFFLINE:
2162                case SDEV_BLOCK:
2163                        break;
2164                default:
2165                        goto illegal;
2166                }
2167                break;
2168
2169        case SDEV_DEL:
2170                switch (oldstate) {
2171                case SDEV_CREATED:
2172                case SDEV_RUNNING:
2173                case SDEV_OFFLINE:
2174                case SDEV_TRANSPORT_OFFLINE:
2175                case SDEV_CANCEL:
2176                        break;
2177                default:
2178                        goto illegal;
2179                }
2180                break;
2181
2182        }
2183        sdev->sdev_state = state;
2184        return 0;
2185
2186 illegal:
2187        SCSI_LOG_ERROR_RECOVERY(1, 
2188                                sdev_printk(KERN_ERR, sdev,
2189                                            "Illegal state transition %s->%s\n",
2190                                            scsi_device_state_name(oldstate),
2191                                            scsi_device_state_name(state))
2192                                );
2193        return -EINVAL;
2194}
2195EXPORT_SYMBOL(scsi_device_set_state);
2196
2197/**
2198 *      sdev_evt_emit - emit a single SCSI device uevent
2199 *      @sdev: associated SCSI device
2200 *      @evt: event to emit
2201 *
2202 *      Send a single uevent (scsi_event) to the associated scsi_device.
2203 */
2204static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt)
2205{
2206        int idx = 0;
2207        char *envp[3];
2208
2209        switch (evt->evt_type) {
2210        case SDEV_EVT_MEDIA_CHANGE:
2211                envp[idx++] = "SDEV_MEDIA_CHANGE=1";
2212                break;
2213
2214        default:
2215                /* do nothing */
2216                break;
2217        }
2218
2219        envp[idx++] = NULL;
2220
2221        kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
2222}
2223
2224/**
2225 *      sdev_evt_thread - send a uevent for each scsi event
2226 *      @work: work struct for scsi_device
2227 *
2228 *      Dispatch queued events to their associated scsi_device kobjects
2229 *      as uevents.
2230 */
2231void scsi_evt_thread(struct work_struct *work)
2232{
2233        struct scsi_device *sdev;
2234        LIST_HEAD(event_list);
2235
2236        sdev = container_of(work, struct scsi_device, event_work);
2237
2238        while (1) {
2239                struct scsi_event *evt;
2240                struct list_head *this, *tmp;
2241                unsigned long flags;
2242
2243                spin_lock_irqsave(&sdev->list_lock, flags);
2244                list_splice_init(&sdev->event_list, &event_list);
2245                spin_unlock_irqrestore(&sdev->list_lock, flags);
2246
2247                if (list_empty(&event_list))
2248                        break;
2249
2250                list_for_each_safe(this, tmp, &event_list) {
2251                        evt = list_entry(this, struct scsi_event, node);
2252                        list_del(&evt->node);
2253                        scsi_evt_emit(sdev, evt);
2254                        kfree(evt);
2255                }
2256        }
2257}
2258
2259/**
2260 *      sdev_evt_send - send asserted event to uevent thread
2261 *      @sdev: scsi_device event occurred on
2262 *      @evt: event to send
2263 *
2264 *      Assert scsi device event asynchronously.
2265 */
2266void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt)
2267{
2268        unsigned long flags;
2269
2270#if 0
2271        /* FIXME: currently this check eliminates all media change events
2272         * for polled devices.  Need to update to discriminate between AN
2273         * and polled events */
2274        if (!test_bit(evt->evt_type, sdev->supported_events)) {
2275                kfree(evt);
2276                return;
2277        }
2278#endif
2279
2280        spin_lock_irqsave(&sdev->list_lock, flags);
2281        list_add_tail(&evt->node, &sdev->event_list);
2282        schedule_work(&sdev->event_work);
2283        spin_unlock_irqrestore(&sdev->list_lock, flags);
2284}
2285EXPORT_SYMBOL_GPL(sdev_evt_send);
2286
2287/**
2288 *      sdev_evt_alloc - allocate a new scsi event
2289 *      @evt_type: type of event to allocate
2290 *      @gfpflags: GFP flags for allocation
2291 *
2292 *      Allocates and returns a new scsi_event.
2293 */
2294struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
2295                                  gfp_t gfpflags)
2296{
2297        struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags);
2298        if (!evt)
2299                return NULL;
2300
2301        evt->evt_type = evt_type;
2302        INIT_LIST_HEAD(&evt->node);
2303
2304        /* evt_type-specific initialization, if any */
2305        switch (evt_type) {
2306        case SDEV_EVT_MEDIA_CHANGE:
2307        default:
2308                /* do nothing */
2309                break;
2310        }
2311
2312        return evt;
2313}
2314EXPORT_SYMBOL_GPL(sdev_evt_alloc);
2315
2316/**
2317 *      sdev_evt_send_simple - send asserted event to uevent thread
2318 *      @sdev: scsi_device event occurred on
2319 *      @evt_type: type of event to send
2320 *      @gfpflags: GFP flags for allocation
2321 *
2322 *      Assert scsi device event asynchronously, given an event type.
2323 */
2324void sdev_evt_send_simple(struct scsi_device *sdev,
2325                          enum scsi_device_event evt_type, gfp_t gfpflags)
2326{
2327        struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags);
2328        if (!evt) {
2329                sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n",
2330                            evt_type);
2331                return;
2332        }
2333
2334        sdev_evt_send(sdev, evt);
2335}
2336EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
2337
2338/**
2339 *      scsi_device_quiesce - Block user issued commands.
2340 *      @sdev:  scsi device to quiesce.
2341 *
2342 *      This works by trying to transition to the SDEV_QUIESCE state
2343 *      (which must be a legal transition).  When the device is in this
2344 *      state, only special requests will be accepted, all others will
2345 *      be deferred.  Since special requests may also be requeued requests,
2346 *      a successful return doesn't guarantee the device will be 
2347 *      totally quiescent.
2348 *
2349 *      Must be called with user context, may sleep.
2350 *
2351 *      Returns zero if unsuccessful or an error if not.
2352 */
2353int
2354scsi_device_quiesce(struct scsi_device *sdev)
2355{
2356        int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2357        if (err)
2358                return err;
2359
2360        scsi_run_queue(sdev->request_queue);
2361        while (sdev->device_busy) {
2362                msleep_interruptible(200);
2363                scsi_run_queue(sdev->request_queue);
2364        }
2365        return 0;
2366}
2367EXPORT_SYMBOL(scsi_device_quiesce);
2368
2369/**
2370 *      scsi_device_resume - Restart user issued commands to a quiesced device.
2371 *      @sdev:  scsi device to resume.
2372 *
2373 *      Moves the device from quiesced back to running and restarts the
2374 *      queues.
2375 *
2376 *      Must be called with user context, may sleep.
2377 */
2378void scsi_device_resume(struct scsi_device *sdev)
2379{
2380        /* check if the device state was mutated prior to resume, and if
2381         * so assume the state is being managed elsewhere (for example
2382         * device deleted during suspend)
2383         */
2384        if (sdev->sdev_state != SDEV_QUIESCE ||
2385            scsi_device_set_state(sdev, SDEV_RUNNING))
2386                return;
2387        scsi_run_queue(sdev->request_queue);
2388}
2389EXPORT_SYMBOL(scsi_device_resume);
2390
2391static void
2392device_quiesce_fn(struct scsi_device *sdev, void *data)
2393{
2394        scsi_device_quiesce(sdev);
2395}
2396
2397void
2398scsi_target_quiesce(struct scsi_target *starget)
2399{
2400        starget_for_each_device(starget, NULL, device_quiesce_fn);
2401}
2402EXPORT_SYMBOL(scsi_target_quiesce);
2403
2404static void
2405device_resume_fn(struct scsi_device *sdev, void *data)
2406{
2407        scsi_device_resume(sdev);
2408}
2409
2410void
2411scsi_target_resume(struct scsi_target *starget)
2412{
2413        starget_for_each_device(starget, NULL, device_resume_fn);
2414}
2415EXPORT_SYMBOL(scsi_target_resume);
2416
2417/**
2418 * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state
2419 * @sdev:       device to block
2420 *
2421 * Block request made by scsi lld's to temporarily stop all
2422 * scsi commands on the specified device.  Called from interrupt
2423 * or normal process context.
2424 *
2425 * Returns zero if successful or error if not
2426 *
2427 * Notes:       
2428 *      This routine transitions the device to the SDEV_BLOCK state
2429 *      (which must be a legal transition).  When the device is in this
2430 *      state, all commands are deferred until the scsi lld reenables
2431 *      the device with scsi_device_unblock or device_block_tmo fires.
2432 */
2433int
2434scsi_internal_device_block(struct scsi_device *sdev)
2435{
2436        struct request_queue *q = sdev->request_queue;
2437        unsigned long flags;
2438        int err = 0;
2439
2440        err = scsi_device_set_state(sdev, SDEV_BLOCK);
2441        if (err) {
2442                err = scsi_device_set_state(sdev, SDEV_CREATED_BLOCK);
2443
2444                if (err)
2445                        return err;
2446        }
2447
2448        /* 
2449         * The device has transitioned to SDEV_BLOCK.  Stop the
2450         * block layer from calling the midlayer with this device's
2451         * request queue. 
2452         */
2453        spin_lock_irqsave(q->queue_lock, flags);
2454        blk_stop_queue(q);
2455        spin_unlock_irqrestore(q->queue_lock, flags);
2456
2457        return 0;
2458}
2459EXPORT_SYMBOL_GPL(scsi_internal_device_block);
2460 
2461/**
2462 * scsi_internal_device_unblock - resume a device after a block request
2463 * @sdev:       device to resume
2464 * @new_state:  state to set devices to after unblocking
2465 *
2466 * Called by scsi lld's or the midlayer to restart the device queue
2467 * for the previously suspended scsi device.  Called from interrupt or
2468 * normal process context.
2469 *
2470 * Returns zero if successful or error if not.
2471 *
2472 * Notes:       
2473 *      This routine transitions the device to the SDEV_RUNNING state
2474 *      or to one of the offline states (which must be a legal transition)
2475 *      allowing the midlayer to goose the queue for this device.
2476 */
2477int
2478scsi_internal_device_unblock(struct scsi_device *sdev,
2479                             enum scsi_device_state new_state)
2480{
2481        struct request_queue *q = sdev->request_queue; 
2482        unsigned long flags;
2483
2484        /*
2485         * Try to transition the scsi device to SDEV_RUNNING or one of the
2486         * offlined states and goose the device queue if successful.
2487         */
2488        if ((sdev->sdev_state == SDEV_BLOCK) ||
2489            (sdev->sdev_state == SDEV_TRANSPORT_OFFLINE))
2490                sdev->sdev_state = new_state;
2491        else if (sdev->sdev_state == SDEV_CREATED_BLOCK) {
2492                if (new_state == SDEV_TRANSPORT_OFFLINE ||
2493                    new_state == SDEV_OFFLINE)
2494                        sdev->sdev_state = new_state;
2495                else
2496                        sdev->sdev_state = SDEV_CREATED;
2497        } else if (sdev->sdev_state != SDEV_CANCEL &&
2498                 sdev->sdev_state != SDEV_OFFLINE)
2499                return -EINVAL;
2500
2501        spin_lock_irqsave(q->queue_lock, flags);
2502        blk_start_queue(q);
2503        spin_unlock_irqrestore(q->queue_lock, flags);
2504
2505        return 0;
2506}
2507EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
2508
2509static void
2510device_block(struct scsi_device *sdev, void *data)
2511{
2512        scsi_internal_device_block(sdev);
2513}
2514
2515static int
2516target_block(struct device *dev, void *data)
2517{
2518        if (scsi_is_target_device(dev))
2519                starget_for_each_device(to_scsi_target(dev), NULL,
2520                                        device_block);
2521        return 0;
2522}
2523
2524void
2525scsi_target_block(struct device *dev)
2526{
2527        if (scsi_is_target_device(dev))
2528                starget_for_each_device(to_scsi_target(dev), NULL,
2529                                        device_block);
2530        else
2531                device_for_each_child(dev, NULL, target_block);
2532}
2533EXPORT_SYMBOL_GPL(scsi_target_block);
2534
2535static void
2536device_unblock(struct scsi_device *sdev, void *data)
2537{
2538        scsi_internal_device_unblock(sdev, *(enum scsi_device_state *)data);
2539}
2540
2541static int
2542target_unblock(struct device *dev, void *data)
2543{
2544        if (scsi_is_target_device(dev))
2545                starget_for_each_device(to_scsi_target(dev), data,
2546                                        device_unblock);
2547        return 0;
2548}
2549
2550void
2551scsi_target_unblock(struct device *dev, enum scsi_device_state new_state)
2552{
2553        if (scsi_is_target_device(dev))
2554                starget_for_each_device(to_scsi_target(dev), &new_state,
2555                                        device_unblock);
2556        else
2557                device_for_each_child(dev, &new_state, target_unblock);
2558}
2559EXPORT_SYMBOL_GPL(scsi_target_unblock);
2560
2561/**
2562 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2563 * @sgl:        scatter-gather list
2564 * @sg_count:   number of segments in sg
2565 * @offset:     offset in bytes into sg, on return offset into the mapped area
2566 * @len:        bytes to map, on return number of bytes mapped
2567 *
2568 * Returns virtual address of the start of the mapped page
2569 */
2570void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
2571                          size_t *offset, size_t *len)
2572{
2573        int i;
2574        size_t sg_len = 0, len_complete = 0;
2575        struct scatterlist *sg;
2576        struct page *page;
2577
2578        WARN_ON(!irqs_disabled());
2579
2580        for_each_sg(sgl, sg, sg_count, i) {
2581                len_complete = sg_len; /* Complete sg-entries */
2582                sg_len += sg->length;
2583                if (sg_len > *offset)
2584                        break;
2585        }
2586
2587        if (unlikely(i == sg_count)) {
2588                printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
2589                        "elements %d\n",
2590                       __func__, sg_len, *offset, sg_count);
2591                WARN_ON(1);
2592                return NULL;
2593        }
2594
2595        /* Offset starting from the beginning of first page in this sg-entry */
2596        *offset = *offset - len_complete + sg->offset;
2597
2598        /* Assumption: contiguous pages can be accessed as "page + i" */
2599        page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
2600        *offset &= ~PAGE_MASK;
2601
2602        /* Bytes in this sg-entry from *offset to the end of the page */
2603        sg_len = PAGE_SIZE - *offset;
2604        if (*len > sg_len)
2605                *len = sg_len;
2606
2607        return kmap_atomic(page);
2608}
2609EXPORT_SYMBOL(scsi_kmap_atomic_sg);
2610
2611/**
2612 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
2613 * @virt:       virtual address to be unmapped
2614 */
2615void scsi_kunmap_atomic_sg(void *virt)
2616{
2617        kunmap_atomic(virt);
2618}
2619EXPORT_SYMBOL(scsi_kunmap_atomic_sg);
2620
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