linux-bk/include/linux/blkdev.h
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   1#ifndef _LINUX_BLKDEV_H
   2#define _LINUX_BLKDEV_H
   3
   4#include <linux/config.h>
   5#include <linux/major.h>
   6#include <linux/genhd.h>
   7#include <linux/list.h>
   8#include <linux/timer.h>
   9#include <linux/workqueue.h>
  10#include <linux/pagemap.h>
  11#include <linux/backing-dev.h>
  12#include <linux/wait.h>
  13#include <linux/mempool.h>
  14#include <linux/bio.h>
  15#include <linux/module.h>
  16#include <linux/stringify.h>
  17
  18#include <asm/scatterlist.h>
  19
  20struct request_queue;
  21typedef struct request_queue request_queue_t;
  22struct elevator_s;
  23typedef struct elevator_s elevator_t;
  24struct request_pm_state;
  25
  26#define BLKDEV_MIN_RQ   4
  27#define BLKDEV_MAX_RQ   128     /* Default maximum */
  28
  29/*
  30 * This is the per-process anticipatory I/O scheduler state.
  31 */
  32struct as_io_context {
  33        spinlock_t lock;
  34
  35        void (*dtor)(struct as_io_context *aic); /* destructor */
  36        void (*exit)(struct as_io_context *aic); /* called on task exit */
  37
  38        unsigned long state;
  39        atomic_t nr_queued; /* queued reads & sync writes */
  40        atomic_t nr_dispatched; /* number of requests gone to the drivers */
  41
  42        /* IO History tracking */
  43        /* Thinktime */
  44        unsigned long last_end_request;
  45        unsigned long ttime_total;
  46        unsigned long ttime_samples;
  47        unsigned long ttime_mean;
  48        /* Layout pattern */
  49        unsigned int seek_samples;
  50        sector_t last_request_pos;
  51        u64 seek_total;
  52        sector_t seek_mean;
  53};
  54
  55/*
  56 * This is the per-process I/O subsystem state.  It is refcounted and
  57 * kmalloc'ed. Currently all fields are modified in process io context
  58 * (apart from the atomic refcount), so require no locking.
  59 */
  60struct io_context {
  61        atomic_t refcount;
  62        pid_t pid;
  63
  64        /*
  65         * For request batching
  66         */
  67        unsigned long last_waited; /* Time last woken after wait for request */
  68        int nr_batch_requests;     /* Number of requests left in the batch */
  69
  70        struct as_io_context *aic;
  71};
  72
  73void put_io_context(struct io_context *ioc);
  74void exit_io_context(void);
  75struct io_context *get_io_context(int gfp_flags);
  76void copy_io_context(struct io_context **pdst, struct io_context **psrc);
  77void swap_io_context(struct io_context **ioc1, struct io_context **ioc2);
  78
  79struct request_list {
  80        int count[2];
  81        mempool_t *rq_pool;
  82        wait_queue_head_t wait[2];
  83};
  84
  85#define BLK_MAX_CDB     16
  86
  87/*
  88 * try to put the fields that are referenced together in the same cacheline
  89 */
  90struct request {
  91        struct list_head queuelist; /* looking for ->queue? you must _not_
  92                                     * access it directly, use
  93                                     * blkdev_dequeue_request! */
  94        unsigned long flags;            /* see REQ_ bits below */
  95
  96        /* Maintain bio traversal state for part by part I/O submission.
  97         * hard_* are block layer internals, no driver should touch them!
  98         */
  99
 100        sector_t sector;                /* next sector to submit */
 101        unsigned long nr_sectors;       /* no. of sectors left to submit */
 102        /* no. of sectors left to submit in the current segment */
 103        unsigned int current_nr_sectors;
 104
 105        sector_t hard_sector;           /* next sector to complete */
 106        unsigned long hard_nr_sectors;  /* no. of sectors left to complete */
 107        /* no. of sectors left to complete in the current segment */
 108        unsigned int hard_cur_sectors;
 109
 110        /* no. of segments left to submit in the current bio */
 111        unsigned short nr_cbio_segments;
 112        /* no. of sectors left to submit in the current bio */
 113        unsigned long nr_cbio_sectors;
 114
 115        struct bio *cbio;               /* next bio to submit */
 116        struct bio *bio;                /* next unfinished bio to complete */
 117        struct bio *biotail;
 118
 119        void *elevator_private;
 120
 121        int rq_status;  /* should split this into a few status bits */
 122        struct gendisk *rq_disk;
 123        int errors;
 124        unsigned long start_time;
 125
 126        /* Number of scatter-gather DMA addr+len pairs after
 127         * physical address coalescing is performed.
 128         */
 129        unsigned short nr_phys_segments;
 130
 131        /* Number of scatter-gather addr+len pairs after
 132         * physical and DMA remapping hardware coalescing is performed.
 133         * This is the number of scatter-gather entries the driver
 134         * will actually have to deal with after DMA mapping is done.
 135         */
 136        unsigned short nr_hw_segments;
 137
 138        int tag;
 139        char *buffer;
 140
 141        int ref_count;
 142        request_queue_t *q;
 143        struct request_list *rl;
 144
 145        struct completion *waiting;
 146        void *special;
 147
 148        /*
 149         * when request is used as a packet command carrier
 150         */
 151        unsigned int cmd_len;
 152        unsigned char cmd[BLK_MAX_CDB];
 153
 154        unsigned int data_len;
 155        void *data;
 156
 157        unsigned int sense_len;
 158        void *sense;
 159
 160        unsigned int timeout;
 161
 162        /*
 163         * For Power Management requests
 164         */
 165        struct request_pm_state *pm;
 166};
 167
 168/*
 169 * first three bits match BIO_RW* bits, important
 170 */
 171enum rq_flag_bits {
 172        __REQ_RW,               /* not set, read. set, write */
 173        __REQ_FAILFAST,         /* no low level driver retries */
 174        __REQ_SOFTBARRIER,      /* may not be passed by ioscheduler */
 175        __REQ_HARDBARRIER,      /* may not be passed by drive either */
 176        __REQ_CMD,              /* is a regular fs rw request */
 177        __REQ_NOMERGE,          /* don't touch this for merging */
 178        __REQ_STARTED,          /* drive already may have started this one */
 179        __REQ_DONTPREP,         /* don't call prep for this one */
 180        __REQ_QUEUED,           /* uses queueing */
 181        /*
 182         * for ATA/ATAPI devices
 183         */
 184        __REQ_PC,               /* packet command (special) */
 185        __REQ_BLOCK_PC,         /* queued down pc from block layer */
 186        __REQ_SENSE,            /* sense retrival */
 187
 188        __REQ_FAILED,           /* set if the request failed */
 189        __REQ_QUIET,            /* don't worry about errors */
 190        __REQ_SPECIAL,          /* driver suplied command */
 191        __REQ_DRIVE_CMD,
 192        __REQ_DRIVE_TASK,
 193        __REQ_DRIVE_TASKFILE,
 194        __REQ_PREEMPT,          /* set for "ide_preempt" requests */
 195        __REQ_PM_SUSPEND,       /* suspend request */
 196        __REQ_PM_RESUME,        /* resume request */
 197        __REQ_PM_SHUTDOWN,      /* shutdown request */
 198        __REQ_NR_BITS,          /* stops here */
 199};
 200
 201#define REQ_RW          (1 << __REQ_RW)
 202#define REQ_FAILFAST    (1 << __REQ_FAILFAST)
 203#define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER)
 204#define REQ_HARDBARRIER (1 << __REQ_HARDBARRIER)
 205#define REQ_CMD         (1 << __REQ_CMD)
 206#define REQ_NOMERGE     (1 << __REQ_NOMERGE)
 207#define REQ_STARTED     (1 << __REQ_STARTED)
 208#define REQ_DONTPREP    (1 << __REQ_DONTPREP)
 209#define REQ_QUEUED      (1 << __REQ_QUEUED)
 210#define REQ_PC          (1 << __REQ_PC)
 211#define REQ_BLOCK_PC    (1 << __REQ_BLOCK_PC)
 212#define REQ_SENSE       (1 << __REQ_SENSE)
 213#define REQ_FAILED      (1 << __REQ_FAILED)
 214#define REQ_QUIET       (1 << __REQ_QUIET)
 215#define REQ_SPECIAL     (1 << __REQ_SPECIAL)
 216#define REQ_DRIVE_CMD   (1 << __REQ_DRIVE_CMD)
 217#define REQ_DRIVE_TASK  (1 << __REQ_DRIVE_TASK)
 218#define REQ_DRIVE_TASKFILE      (1 << __REQ_DRIVE_TASKFILE)
 219#define REQ_PREEMPT     (1 << __REQ_PREEMPT)
 220#define REQ_PM_SUSPEND  (1 << __REQ_PM_SUSPEND)
 221#define REQ_PM_RESUME   (1 << __REQ_PM_RESUME)
 222#define REQ_PM_SHUTDOWN (1 << __REQ_PM_SHUTDOWN)
 223
 224/*
 225 * State information carried for REQ_PM_SUSPEND and REQ_PM_RESUME
 226 * requests. Some step values could eventually be made generic.
 227 */
 228struct request_pm_state
 229{
 230        /* PM state machine step value, currently driver specific */
 231        int     pm_step;
 232        /* requested PM state value (S1, S2, S3, S4, ...) */
 233        u32     pm_state;
 234        void*   data;           /* for driver use */
 235};
 236
 237#include <linux/elevator.h>
 238
 239typedef int (merge_request_fn) (request_queue_t *, struct request *,
 240                                struct bio *);
 241typedef int (merge_requests_fn) (request_queue_t *, struct request *,
 242                                 struct request *);
 243typedef void (request_fn_proc) (request_queue_t *q);
 244typedef int (make_request_fn) (request_queue_t *q, struct bio *bio);
 245typedef int (prep_rq_fn) (request_queue_t *, struct request *);
 246typedef void (unplug_fn) (request_queue_t *);
 247
 248struct bio_vec;
 249typedef int (merge_bvec_fn) (request_queue_t *, struct bio *, struct bio_vec *);
 250typedef void (activity_fn) (void *data, int rw);
 251
 252enum blk_queue_state {
 253        Queue_down,
 254        Queue_up,
 255};
 256
 257#define BLK_TAGS_PER_LONG       (sizeof(unsigned long) * 8)
 258#define BLK_TAGS_MASK           (BLK_TAGS_PER_LONG - 1)
 259
 260struct blk_queue_tag {
 261        struct request **tag_index;     /* map of busy tags */
 262        unsigned long *tag_map;         /* bit map of free/busy tags */
 263        struct list_head busy_list;     /* fifo list of busy tags */
 264        int busy;                       /* current depth */
 265        int max_depth;                  /* what we will send to device */
 266        int real_max_depth;             /* what the array can hold */
 267        atomic_t refcnt;                /* map can be shared */
 268};
 269
 270struct request_queue
 271{
 272        /*
 273         * Together with queue_head for cacheline sharing
 274         */
 275        struct list_head        queue_head;
 276        struct request          *last_merge;
 277        elevator_t              elevator;
 278
 279        /*
 280         * the queue request freelist, one for reads and one for writes
 281         */
 282        struct request_list     rq;
 283
 284        request_fn_proc         *request_fn;
 285        merge_request_fn        *back_merge_fn;
 286        merge_request_fn        *front_merge_fn;
 287        merge_requests_fn       *merge_requests_fn;
 288        make_request_fn         *make_request_fn;
 289        prep_rq_fn              *prep_rq_fn;
 290        unplug_fn               *unplug_fn;
 291        merge_bvec_fn           *merge_bvec_fn;
 292        activity_fn             *activity_fn;
 293
 294        /*
 295         * Auto-unplugging state
 296         */
 297        struct timer_list       unplug_timer;
 298        int                     unplug_thresh;  /* After this many requests */
 299        unsigned long           unplug_delay;   /* After this many jiffies */
 300        struct work_struct      unplug_work;
 301
 302        struct backing_dev_info backing_dev_info;
 303
 304        /*
 305         * The queue owner gets to use this for whatever they like.
 306         * ll_rw_blk doesn't touch it.
 307         */
 308        void                    *queuedata;
 309
 310        void                    *activity_data;
 311
 312        /*
 313         * queue needs bounce pages for pages above this limit
 314         */
 315        unsigned long           bounce_pfn;
 316        int                     bounce_gfp;
 317
 318        /*
 319         * various queue flags, see QUEUE_* below
 320         */
 321        unsigned long           queue_flags;
 322
 323        /*
 324         * protects queue structures from reentrancy
 325         */
 326        spinlock_t              *queue_lock;
 327
 328        /*
 329         * queue kobject
 330         */
 331        struct kobject kobj;
 332
 333        /*
 334         * queue settings
 335         */
 336        unsigned long           nr_requests;    /* Max # of requests */
 337        unsigned int            nr_congestion_on;
 338        unsigned int            nr_congestion_off;
 339
 340        unsigned short          max_sectors;
 341        unsigned short          max_phys_segments;
 342        unsigned short          max_hw_segments;
 343        unsigned short          hardsect_size;
 344        unsigned int            max_segment_size;
 345
 346        unsigned long           seg_boundary_mask;
 347        unsigned int            dma_alignment;
 348
 349        struct blk_queue_tag    *queue_tags;
 350
 351        atomic_t                refcnt;
 352
 353        unsigned int            in_flight;
 354
 355        /*
 356         * sg stuff
 357         */
 358        unsigned int            sg_timeout;
 359        unsigned int            sg_reserved_size;
 360};
 361
 362#define RQ_INACTIVE             (-1)
 363#define RQ_ACTIVE               1
 364#define RQ_SCSI_BUSY            0xffff
 365#define RQ_SCSI_DONE            0xfffe
 366#define RQ_SCSI_DISCONNECTING   0xffe0
 367
 368#define QUEUE_FLAG_CLUSTER      0       /* cluster several segments into 1 */
 369#define QUEUE_FLAG_QUEUED       1       /* uses generic tag queueing */
 370#define QUEUE_FLAG_STOPPED      2       /* queue is stopped */
 371#define QUEUE_FLAG_READFULL     3       /* write queue has been filled */
 372#define QUEUE_FLAG_WRITEFULL    4       /* read queue has been filled */
 373#define QUEUE_FLAG_DEAD         5       /* queue being torn down */
 374#define QUEUE_FLAG_REENTER      6       /* Re-entrancy avoidance */
 375#define QUEUE_FLAG_PLUGGED      7       /* queue is plugged */
 376
 377#define blk_queue_plugged(q)    test_bit(QUEUE_FLAG_PLUGGED, &(q)->queue_flags)
 378#define blk_queue_tagged(q)     test_bit(QUEUE_FLAG_QUEUED, &(q)->queue_flags)
 379#define blk_queue_stopped(q)    test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
 380
 381#define blk_fs_request(rq)      ((rq)->flags & REQ_CMD)
 382#define blk_pc_request(rq)      ((rq)->flags & REQ_BLOCK_PC)
 383#define blk_noretry_request(rq) ((rq)->flags & REQ_FAILFAST)
 384#define blk_rq_started(rq)      ((rq)->flags & REQ_STARTED)
 385
 386#define blk_account_rq(rq)      (blk_rq_started(rq) && blk_fs_request(rq))
 387
 388#define blk_pm_suspend_request(rq)      ((rq)->flags & REQ_PM_SUSPEND)
 389#define blk_pm_resume_request(rq)       ((rq)->flags & REQ_PM_RESUME)
 390#define blk_pm_request(rq)      \
 391        ((rq)->flags & (REQ_PM_SUSPEND | REQ_PM_RESUME))
 392
 393#define list_entry_rq(ptr)      list_entry((ptr), struct request, queuelist)
 394
 395#define rq_data_dir(rq)         ((rq)->flags & 1)
 396
 397static inline int blk_queue_full(struct request_queue *q, int rw)
 398{
 399        if (rw == READ)
 400                return test_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 401        return test_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 402}
 403
 404static inline void blk_set_queue_full(struct request_queue *q, int rw)
 405{
 406        if (rw == READ)
 407                set_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 408        else
 409                set_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 410}
 411
 412static inline void blk_clear_queue_full(struct request_queue *q, int rw)
 413{
 414        if (rw == READ)
 415                clear_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 416        else
 417                clear_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 418}
 419
 420
 421/*
 422 * mergeable request must not have _NOMERGE or _BARRIER bit set, nor may
 423 * it already be started by driver.
 424 */
 425#define RQ_NOMERGE_FLAGS        \
 426        (REQ_NOMERGE | REQ_STARTED | REQ_HARDBARRIER | REQ_SOFTBARRIER)
 427#define rq_mergeable(rq)        \
 428        (!((rq)->flags & RQ_NOMERGE_FLAGS) && blk_fs_request((rq)))
 429
 430/*
 431 * noop, requests are automagically marked as active/inactive by I/O
 432 * scheduler -- see elv_next_request
 433 */
 434#define blk_queue_headactive(q, head_active)
 435
 436/* current index into bio being processed for submission */
 437#define blk_rq_idx(rq)  ((rq)->cbio->bi_vcnt - (rq)->nr_cbio_segments)
 438
 439/* current bio vector being processed */
 440#define blk_rq_vec(rq)  (bio_iovec_idx((rq)->cbio, blk_rq_idx(rq)))
 441
 442/* current offset with respect to start of the segment being submitted */
 443#define blk_rq_offset(rq) \
 444        (((rq)->hard_cur_sectors - (rq)->current_nr_sectors) << 9)
 445
 446/*
 447 * temporarily mapping a (possible) highmem bio (typically for PIO transfer)
 448 */
 449
 450/* Assumes rq->cbio != NULL */
 451static inline char * rq_map_buffer(struct request *rq, unsigned long *flags)
 452{
 453        return (__bio_kmap_irq(rq->cbio, blk_rq_idx(rq), flags)
 454                + blk_rq_offset(rq));
 455}
 456
 457static inline void rq_unmap_buffer(char *buffer, unsigned long *flags)
 458{
 459        __bio_kunmap_irq(buffer, flags);
 460}
 461
 462/*
 463 * q->prep_rq_fn return values
 464 */
 465#define BLKPREP_OK              0       /* serve it */
 466#define BLKPREP_KILL            1       /* fatal error, kill */
 467#define BLKPREP_DEFER           2       /* leave on queue */
 468
 469extern unsigned long blk_max_low_pfn, blk_max_pfn;
 470
 471/*
 472 * standard bounce addresses:
 473 *
 474 * BLK_BOUNCE_HIGH      : bounce all highmem pages
 475 * BLK_BOUNCE_ANY       : don't bounce anything
 476 * BLK_BOUNCE_ISA       : bounce pages above ISA DMA boundary
 477 */
 478#define BLK_BOUNCE_HIGH         ((u64)blk_max_low_pfn << PAGE_SHIFT)
 479#define BLK_BOUNCE_ANY          ((u64)blk_max_pfn << PAGE_SHIFT)
 480#define BLK_BOUNCE_ISA          (ISA_DMA_THRESHOLD)
 481
 482#ifdef CONFIG_MMU
 483extern int init_emergency_isa_pool(void);
 484extern void blk_queue_bounce(request_queue_t *q, struct bio **bio);
 485#else
 486static inline int init_emergency_isa_pool(void)
 487{
 488        return 0;
 489}
 490static inline void blk_queue_bounce(request_queue_t *q, struct bio **bio)
 491{
 492}
 493#endif /* CONFIG_MMU */
 494
 495#define rq_for_each_bio(_bio, rq)       \
 496        if ((rq->bio))                  \
 497                for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)
 498
 499struct sec_size {
 500        unsigned block_size;
 501        unsigned block_size_bits;
 502};
 503
 504extern int blk_register_queue(struct gendisk *disk);
 505extern void blk_unregister_queue(struct gendisk *disk);
 506extern void register_disk(struct gendisk *dev);
 507extern void generic_make_request(struct bio *bio);
 508extern void blk_put_request(struct request *);
 509extern void blk_attempt_remerge(request_queue_t *, struct request *);
 510extern void __blk_attempt_remerge(request_queue_t *, struct request *);
 511extern struct request *blk_get_request(request_queue_t *, int, int);
 512extern void blk_put_request(struct request *);
 513extern void blk_insert_request(request_queue_t *, struct request *, int, void *, int);
 514extern void blk_requeue_request(request_queue_t *, struct request *);
 515extern void blk_plug_device(request_queue_t *);
 516extern int blk_remove_plug(request_queue_t *);
 517extern void blk_recount_segments(request_queue_t *, struct bio *);
 518extern int blk_phys_contig_segment(request_queue_t *q, struct bio *, struct bio *);
 519extern int blk_hw_contig_segment(request_queue_t *q, struct bio *, struct bio *);
 520extern int scsi_cmd_ioctl(struct file *, struct gendisk *, unsigned int, void __user *);
 521extern void blk_start_queue(request_queue_t *q);
 522extern void blk_stop_queue(request_queue_t *q);
 523extern void __blk_stop_queue(request_queue_t *q);
 524extern void blk_run_queue(request_queue_t *);
 525extern void blk_queue_activity_fn(request_queue_t *, activity_fn *, void *);
 526extern struct request *blk_rq_map_user(request_queue_t *, int, void __user *, unsigned int);
 527extern int blk_rq_unmap_user(struct request *, struct bio *, unsigned int);
 528extern int blk_execute_rq(request_queue_t *, struct gendisk *, struct request *);
 529
 530static inline request_queue_t *bdev_get_queue(struct block_device *bdev)
 531{
 532        return bdev->bd_disk->queue;
 533}
 534
 535static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
 536                                       struct page *page)
 537{
 538        if (bdi && bdi->unplug_io_fn)
 539                bdi->unplug_io_fn(bdi, page);
 540}
 541
 542static inline void blk_run_address_space(struct address_space *mapping)
 543{
 544        if (mapping)
 545                blk_run_backing_dev(mapping->backing_dev_info, NULL);
 546}
 547
 548/*
 549 * end_request() and friends. Must be called with the request queue spinlock
 550 * acquired. All functions called within end_request() _must_be_ atomic.
 551 *
 552 * Several drivers define their own end_request and call
 553 * end_that_request_first() and end_that_request_last()
 554 * for parts of the original function. This prevents
 555 * code duplication in drivers.
 556 */
 557extern int end_that_request_first(struct request *, int, int);
 558extern int end_that_request_chunk(struct request *, int, int);
 559extern void end_that_request_last(struct request *);
 560extern int process_that_request_first(struct request *, unsigned int);
 561extern void end_request(struct request *req, int uptodate);
 562
 563static inline void blkdev_dequeue_request(struct request *req)
 564{
 565        BUG_ON(list_empty(&req->queuelist));
 566
 567        list_del_init(&req->queuelist);
 568
 569        if (req->rl)
 570                elv_remove_request(req->q, req);
 571}
 572
 573/*
 574 * Access functions for manipulating queue properties
 575 */
 576extern request_queue_t *blk_init_queue(request_fn_proc *, spinlock_t *);
 577extern void blk_cleanup_queue(request_queue_t *);
 578extern void blk_queue_make_request(request_queue_t *, make_request_fn *);
 579extern void blk_queue_bounce_limit(request_queue_t *, u64);
 580extern void blk_queue_max_sectors(request_queue_t *, unsigned short);
 581extern void blk_queue_max_phys_segments(request_queue_t *, unsigned short);
 582extern void blk_queue_max_hw_segments(request_queue_t *, unsigned short);
 583extern void blk_queue_max_segment_size(request_queue_t *, unsigned int);
 584extern void blk_queue_hardsect_size(request_queue_t *, unsigned short);
 585extern void blk_queue_stack_limits(request_queue_t *t, request_queue_t *b);
 586extern void blk_queue_segment_boundary(request_queue_t *, unsigned long);
 587extern void blk_queue_prep_rq(request_queue_t *, prep_rq_fn *pfn);
 588extern void blk_queue_merge_bvec(request_queue_t *, merge_bvec_fn *);
 589extern void blk_queue_dma_alignment(request_queue_t *, int);
 590extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);
 591
 592extern int blk_rq_map_sg(request_queue_t *, struct request *, struct scatterlist *);
 593extern void blk_dump_rq_flags(struct request *, char *);
 594extern void generic_unplug_device(request_queue_t *);
 595extern void __generic_unplug_device(request_queue_t *);
 596extern long nr_blockdev_pages(void);
 597
 598int blk_get_queue(request_queue_t *);
 599request_queue_t *blk_alloc_queue(int);
 600#define blk_put_queue(q) blk_cleanup_queue((q))
 601
 602/*
 603 * tag stuff
 604 */
 605#define blk_queue_tag_depth(q)          ((q)->queue_tags->busy)
 606#define blk_queue_tag_queue(q)          ((q)->queue_tags->busy < (q)->queue_tags->max_depth)
 607#define blk_rq_tagged(rq)               ((rq)->flags & REQ_QUEUED)
 608extern int blk_queue_start_tag(request_queue_t *, struct request *);
 609extern struct request *blk_queue_find_tag(request_queue_t *, int);
 610extern void blk_queue_end_tag(request_queue_t *, struct request *);
 611extern int blk_queue_init_tags(request_queue_t *, int, struct blk_queue_tag *);
 612extern void blk_queue_free_tags(request_queue_t *);
 613extern int blk_queue_resize_tags(request_queue_t *, int);
 614extern void blk_queue_invalidate_tags(request_queue_t *);
 615extern long blk_congestion_wait(int rw, long timeout);
 616
 617extern void blk_rq_bio_prep(request_queue_t *, struct request *, struct bio *);
 618extern void blk_rq_prep_restart(struct request *);
 619
 620#define MAX_PHYS_SEGMENTS 128
 621#define MAX_HW_SEGMENTS 128
 622#define MAX_SECTORS 255
 623
 624#define MAX_SEGMENT_SIZE        65536
 625
 626#define blkdev_entry_to_request(entry) list_entry((entry), struct request, queuelist)
 627
 628extern void drive_stat_acct(struct request *, int, int);
 629
 630static inline int queue_hardsect_size(request_queue_t *q)
 631{
 632        int retval = 512;
 633
 634        if (q && q->hardsect_size)
 635                retval = q->hardsect_size;
 636
 637        return retval;
 638}
 639
 640static inline int bdev_hardsect_size(struct block_device *bdev)
 641{
 642        return queue_hardsect_size(bdev_get_queue(bdev));
 643}
 644
 645static inline int queue_dma_alignment(request_queue_t *q)
 646{
 647        int retval = 511;
 648
 649        if (q && q->dma_alignment)
 650                retval = q->dma_alignment;
 651
 652        return retval;
 653}
 654
 655static inline int bdev_dma_aligment(struct block_device *bdev)
 656{
 657        return queue_dma_alignment(bdev_get_queue(bdev));
 658}
 659
 660#define blk_finished_io(nsects) do { } while (0)
 661#define blk_started_io(nsects)  do { } while (0)
 662
 663/* assumes size > 256 */
 664static inline unsigned int blksize_bits(unsigned int size)
 665{
 666        unsigned int bits = 8;
 667        do {
 668                bits++;
 669                size >>= 1;
 670        } while (size > 256);
 671        return bits;
 672}
 673
 674extern inline unsigned int block_size(struct block_device *bdev)
 675{
 676        return bdev->bd_block_size;
 677}
 678
 679typedef struct {struct page *v;} Sector;
 680
 681unsigned char *read_dev_sector(struct block_device *, sector_t, Sector *);
 682
 683static inline void put_dev_sector(Sector p)
 684{
 685        page_cache_release(p.v);
 686}
 687
 688struct work_struct;
 689int kblockd_schedule_work(struct work_struct *work);
 690void kblockd_flush(void);
 691
 692#ifdef CONFIG_LBD
 693# include <asm/div64.h>
 694# define sector_div(a, b) do_div(a, b)
 695#else
 696# define sector_div(n, b)( \
 697{ \
 698        int _res; \
 699        _res = (n) % (b); \
 700        (n) /= (b); \
 701        _res; \
 702} \
 703)
 704#endif 
 705
 706#define MODULE_ALIAS_BLOCKDEV(major,minor) \
 707        MODULE_ALIAS("block-major-" __stringify(major) "-" __stringify(minor))
 708#define MODULE_ALIAS_BLOCKDEV_MAJOR(major) \
 709        MODULE_ALIAS("block-major-" __stringify(major) "-*")
 710
 711
 712#endif
 713
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