include/linux/blkdev.h

   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
  20 struct request_queue;
  21 typedef struct request_queue request_queue_t;
  22 struct elevator_queue;
  23 typedef struct elevator_queue elevator_t;
  24 struct 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  */
  32 struct 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 struct cfq_queue;
  56 struct cfq_io_context {
  57         /*
  58          * circular list of cfq_io_contexts belonging to a process io context
  59          */
  60         struct list_head list;
  61         struct cfq_queue *cfqq;
  62         void *key;
  63
  64         struct io_context *ioc;
  65
  66         unsigned long last_end_request;
  67         unsigned long last_queue;
  68         unsigned long ttime_total;
  69         unsigned long ttime_samples;
  70         unsigned long ttime_mean;
  71
  72         void (*dtor)(struct cfq_io_context *);
  73         void (*exit)(struct cfq_io_context *);
  74 };
  75
  76 /*
  77  * This is the per-process I/O subsystem state.  It is refcounted and
  78  * kmalloc'ed. Currently all fields are modified in process io context
  79  * (apart from the atomic refcount), so require no locking.
  80  */
  81 struct io_context {
  82         atomic_t refcount;
  83         struct task_struct *task;
  84
  85         int (*set_ioprio)(struct io_context *, unsigned int);
  86
  87         /*
  88          * For request batching
  89          */
  90         unsigned long last_waited; /* Time last woken after wait for request */
  91         int nr_batch_requests;     /* Number of requests left in the batch */
  92
  93         struct as_io_context *aic;
  94         struct cfq_io_context *cic;
  95 };
  96
  97 void put_io_context(struct io_context *ioc);
  98 void exit_io_context(void);
  99 struct io_context *current_io_context(int gfp_flags);
 100 struct io_context *get_io_context(int gfp_flags);
 101 void copy_io_context(struct io_context **pdst, struct io_context **psrc);
 102 void swap_io_context(struct io_context **ioc1, struct io_context **ioc2);
 103
 104 struct request;
 105 typedef void (rq_end_io_fn)(struct request *);
 106
 107 struct request_list {
 108         int count[2];
 109         int starved[2];
 110         mempool_t *rq_pool;
 111         wait_queue_head_t wait[2];
 112         wait_queue_head_t drain;
 113 };
 114
 115 #define BLK_MAX_CDB     16
 116
 117 /*
 118  * try to put the fields that are referenced together in the same cacheline
 119  */
 120 struct request {
 121         struct list_head queuelist; /* looking for ->queue? you must _not_
 122                                      * access it directly, use
 123                                      * blkdev_dequeue_request! */
 124         unsigned long flags;            /* see REQ_ bits below */
 125
 126         /* Maintain bio traversal state for part by part I/O submission.
 127          * hard_* are block layer internals, no driver should touch them!
 128          */
 129
 130         sector_t sector;                /* next sector to submit */
 131         unsigned long nr_sectors;       /* no. of sectors left to submit */
 132         /* no. of sectors left to submit in the current segment */
 133         unsigned int current_nr_sectors;
 134
 135         sector_t hard_sector;           /* next sector to complete */
 136         unsigned long hard_nr_sectors;  /* no. of sectors left to complete */
 137         /* no. of sectors left to complete in the current segment */
 138         unsigned int hard_cur_sectors;
 139
 140         struct bio *bio;
 141         struct bio *biotail;
 142
 143         void *elevator_private;
 144
 145         unsigned short ioprio;
 146
 147         int rq_status;  /* should split this into a few status bits */
 148         struct gendisk *rq_disk;
 149         int errors;
 150         unsigned long start_time;
 151
 152         /* Number of scatter-gather DMA addr+len pairs after
 153          * physical address coalescing is performed.
 154          */
 155         unsigned short nr_phys_segments;
 156
 157         /* Number of scatter-gather addr+len pairs after
 158          * physical and DMA remapping hardware coalescing is performed.
 159          * This is the number of scatter-gather entries the driver
 160          * will actually have to deal with after DMA mapping is done.
 161          */
 162         unsigned short nr_hw_segments;
 163
 164         int tag;
 165         char *buffer;
 166
 167         int ref_count;
 168         request_queue_t *q;
 169         struct request_list *rl;
 170
 171         struct completion *waiting;
 172         void *special;
 173
 174         /*
 175          * when request is used as a packet command carrier
 176          */
 177         unsigned int cmd_len;
 178         unsigned char cmd[BLK_MAX_CDB];
 179
 180         unsigned int data_len;
 181         void *data;
 182
 183         unsigned int sense_len;
 184         void *sense;
 185
 186         unsigned int timeout;
 187
 188         /*
 189          * For Power Management requests
 190          */
 191         struct request_pm_state *pm;
 192
 193         /*
 194          * completion callback. end_io_data should be folded in with waiting
 195          */
 196         rq_end_io_fn *end_io;
 197         void *end_io_data;
 198 };
 199
 200 /*
 201  * first three bits match BIO_RW* bits, important
 202  */
 203 enum rq_flag_bits {
 204         __REQ_RW,               /* not set, read. set, write */
 205         __REQ_FAILFAST,         /* no low level driver retries */
 206         __REQ_SORTED,           /* elevator knows about this request */
 207         __REQ_SOFTBARRIER,      /* may not be passed by ioscheduler */
 208         __REQ_HARDBARRIER,      /* may not be passed by drive either */
 209         __REQ_CMD,              /* is a regular fs rw request */
 210         __REQ_NOMERGE,          /* don't touch this for merging */
 211         __REQ_STARTED,          /* drive already may have started this one */
 212         __REQ_DONTPREP,         /* don't call prep for this one */
 213         __REQ_QUEUED,           /* uses queueing */
 214         /*
 215          * for ATA/ATAPI devices
 216          */
 217         __REQ_PC,               /* packet command (special) */
 218         __REQ_BLOCK_PC,         /* queued down pc from block layer */
 219         __REQ_SENSE,            /* sense retrival */
 220
 221         __REQ_FAILED,           /* set if the request failed */
 222         __REQ_QUIET,            /* don't worry about errors */
 223         __REQ_SPECIAL,          /* driver suplied command */
 224         __REQ_DRIVE_CMD,
 225         __REQ_DRIVE_TASK,
 226         __REQ_DRIVE_TASKFILE,
 227         __REQ_PREEMPT,          /* set for "ide_preempt" requests */
 228         __REQ_PM_SUSPEND,       /* suspend request */
 229         __REQ_PM_RESUME,        /* resume request */
 230         __REQ_PM_SHUTDOWN,      /* shutdown request */
 231         __REQ_BAR_PREFLUSH,     /* barrier pre-flush done */
 232         __REQ_BAR_POSTFLUSH,    /* barrier post-flush */
 233         __REQ_BAR_FLUSH,        /* rq is the flush request */
 234         __REQ_NR_BITS,          /* stops here */
 235 };
 236
 237 #define REQ_RW          (1 << __REQ_RW)
 238 #define REQ_FAILFAST    (1 << __REQ_FAILFAST)
 239 #define REQ_SORTED      (1 << __REQ_SORTED)
 240 #define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER)
 241 #define REQ_HARDBARRIER (1 << __REQ_HARDBARRIER)
 242 #define REQ_CMD         (1 << __REQ_CMD)
 243 #define REQ_NOMERGE     (1 << __REQ_NOMERGE)
 244 #define REQ_STARTED     (1 << __REQ_STARTED)
 245 #define REQ_DONTPREP    (1 << __REQ_DONTPREP)
 246 #define REQ_QUEUED      (1 << __REQ_QUEUED)
 247 #define REQ_PC          (1 << __REQ_PC)
 248 #define REQ_BLOCK_PC    (1 << __REQ_BLOCK_PC)
 249 #define REQ_SENSE       (1 << __REQ_SENSE)
 250 #define REQ_FAILED      (1 << __REQ_FAILED)
 251 #define REQ_QUIET       (1 << __REQ_QUIET)
 252 #define REQ_SPECIAL     (1 << __REQ_SPECIAL)
 253 #define REQ_DRIVE_CMD   (1 << __REQ_DRIVE_CMD)
 254 #define REQ_DRIVE_TASK  (1 << __REQ_DRIVE_TASK)
 255 #define REQ_DRIVE_TASKFILE      (1 << __REQ_DRIVE_TASKFILE)
 256 #define REQ_PREEMPT     (1 << __REQ_PREEMPT)
 257 #define REQ_PM_SUSPEND  (1 << __REQ_PM_SUSPEND)
 258 #define REQ_PM_RESUME   (1 << __REQ_PM_RESUME)
 259 #define REQ_PM_SHUTDOWN (1 << __REQ_PM_SHUTDOWN)
 260 #define REQ_BAR_PREFLUSH        (1 << __REQ_BAR_PREFLUSH)
 261 #define REQ_BAR_POSTFLUSH       (1 << __REQ_BAR_POSTFLUSH)
 262 #define REQ_BAR_FLUSH   (1 << __REQ_BAR_FLUSH)
 263
 264 /*
 265  * State information carried for REQ_PM_SUSPEND and REQ_PM_RESUME
 266  * requests. Some step values could eventually be made generic.
 267  */
 268 struct request_pm_state
 269 {
 270         /* PM state machine step value, currently driver specific */
 271         int     pm_step;
 272         /* requested PM state value (S1, S2, S3, S4, ...) */
 273         u32     pm_state;
 274         void*   data;           /* for driver use */
 275 };
 276
 277 #include <linux/elevator.h>
 278
 279 typedef int (merge_request_fn) (request_queue_t *, struct request *,
 280                                 struct bio *);
 281 typedef int (merge_requests_fn) (request_queue_t *, struct request *,
 282                                  struct request *);
 283 typedef void (request_fn_proc) (request_queue_t *q);
 284 typedef int (make_request_fn) (request_queue_t *q, struct bio *bio);
 285 typedef int (prep_rq_fn) (request_queue_t *, struct request *);
 286 typedef void (unplug_fn) (request_queue_t *);
 287
 288 struct bio_vec;
 289 typedef int (merge_bvec_fn) (request_queue_t *, struct bio *, struct bio_vec *);
 290 typedef void (activity_fn) (void *data, int rw);
 291 typedef int (issue_flush_fn) (request_queue_t *, struct gendisk *, sector_t *);
 292 typedef int (prepare_flush_fn) (request_queue_t *, struct request *);
 293 typedef void (end_flush_fn) (request_queue_t *, struct request *);
 294
 295 enum blk_queue_state {
 296         Queue_down,
 297         Queue_up,
 298 };
 299
 300 struct blk_queue_tag {
 301         struct request **tag_index;     /* map of busy tags */
 302         unsigned long *tag_map;         /* bit map of free/busy tags */
 303         struct list_head busy_list;     /* fifo list of busy tags */
 304         int busy;                       /* current depth */
 305         int max_depth;                  /* what we will send to device */
 306         int real_max_depth;             /* what the array can hold */
 307         atomic_t refcnt;                /* map can be shared */
 308 };
 309
 310 struct request_queue
 311 {
 312         /*
 313          * Together with queue_head for cacheline sharing
 314          */
 315         struct list_head        queue_head;
 316         struct request          *last_merge;
 317         elevator_t              *elevator;
 318
 319         /*
 320          * the queue request freelist, one for reads and one for writes
 321          */
 322         struct request_list     rq;
 323
 324         request_fn_proc         *request_fn;
 325         merge_request_fn        *back_merge_fn;
 326         merge_request_fn        *front_merge_fn;
 327         merge_requests_fn       *merge_requests_fn;
 328         make_request_fn         *make_request_fn;
 329         prep_rq_fn              *prep_rq_fn;
 330         unplug_fn               *unplug_fn;
 331         merge_bvec_fn           *merge_bvec_fn;
 332         activity_fn             *activity_fn;
 333         issue_flush_fn          *issue_flush_fn;
 334         prepare_flush_fn        *prepare_flush_fn;
 335         end_flush_fn            *end_flush_fn;
 336
 337         /*
 338          * Dispatch queue sorting
 339          */
 340         sector_t                end_sector;
 341         struct request          *boundary_rq;
 342         unsigned int            max_back_kb;
 343
 344         /*
 345          * Auto-unplugging state
 346          */
 347         struct timer_list       unplug_timer;
 348         int                     unplug_thresh;  /* After this many requests */
 349         unsigned long           unplug_delay;   /* After this many jiffies */
 350         struct work_struct      unplug_work;
 351
 352         struct backing_dev_info backing_dev_info;
 353
 354         /*
 355          * The queue owner gets to use this for whatever they like.
 356          * ll_rw_blk doesn't touch it.
 357          */
 358         void                    *queuedata;
 359
 360         void                    *activity_data;
 361
 362         /*
 363          * queue needs bounce pages for pages above this limit
 364          */
 365         unsigned long           bounce_pfn;
 366         unsigned int            bounce_gfp;
 367
 368         /*
 369          * various queue flags, see QUEUE_* below
 370          */
 371         unsigned long           queue_flags;
 372
 373         /*
 374          * protects queue structures from reentrancy. ->__queue_lock should
 375          * _never_ be used directly, it is queue private. always use
 376          * ->queue_lock.
 377          */
 378         spinlock_t              __queue_lock;
 379         spinlock_t              *queue_lock;
 380
 381         /*
 382          * queue kobject
 383          */
 384         struct kobject kobj;
 385
 386         /*
 387          * queue settings
 388          */
 389         unsigned long           nr_requests;    /* Max # of requests */
 390         unsigned int            nr_congestion_on;
 391         unsigned int            nr_congestion_off;
 392         unsigned int            nr_batching;
 393
 394         unsigned short          max_sectors;
 395         unsigned short          max_hw_sectors;
 396         unsigned short          max_phys_segments;
 397         unsigned short          max_hw_segments;
 398         unsigned short          hardsect_size;
 399         unsigned int            max_segment_size;
 400
 401         unsigned long           seg_boundary_mask;
 402         unsigned int            dma_alignment;
 403
 404         struct blk_queue_tag    *queue_tags;
 405
 406         atomic_t                refcnt;
 407
 408         unsigned int            in_flight;
 409
 410         /*
 411          * sg stuff
 412          */
 413         unsigned int            sg_timeout;
 414         unsigned int            sg_reserved_size;
 415         int                     node;
 416
 417         struct list_head        drain_list;
 418
 419         /*
 420          * reserved for flush operations
 421          */
 422         struct request          *flush_rq;
 423         unsigned char           ordered;
 424 };
 425
 426 enum {
 427         QUEUE_ORDERED_NONE,
 428         QUEUE_ORDERED_TAG,
 429         QUEUE_ORDERED_FLUSH,
 430 };
 431
 432 #define RQ_INACTIVE             (-1)
 433 #define RQ_ACTIVE               1
 434 #define RQ_SCSI_BUSY            0xffff
 435 #define RQ_SCSI_DONE            0xfffe
 436 #define RQ_SCSI_DISCONNECTING   0xffe0
 437
 438 #define QUEUE_FLAG_CLUSTER      0       /* cluster several segments into 1 */
 439 #define QUEUE_FLAG_QUEUED       1       /* uses generic tag queueing */
 440 #define QUEUE_FLAG_STOPPED      2       /* queue is stopped */
 441 #define QUEUE_FLAG_READFULL     3       /* write queue has been filled */
 442 #define QUEUE_FLAG_WRITEFULL    4       /* read queue has been filled */
 443 #define QUEUE_FLAG_DEAD         5       /* queue being torn down */
 444 #define QUEUE_FLAG_REENTER      6       /* Re-entrancy avoidance */
 445 #define QUEUE_FLAG_PLUGGED      7       /* queue is plugged */
 446 #define QUEUE_FLAG_DRAIN        8       /* draining queue for sched switch */
 447 #define QUEUE_FLAG_FLUSH        9       /* doing barrier flush sequence */
 448
 449 #define blk_queue_plugged(q)    test_bit(QUEUE_FLAG_PLUGGED, &(q)->queue_flags)
 450 #define blk_queue_tagged(q)     test_bit(QUEUE_FLAG_QUEUED, &(q)->queue_flags)
 451 #define blk_queue_stopped(q)    test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
 452 #define blk_queue_flushing(q)   test_bit(QUEUE_FLAG_FLUSH, &(q)->queue_flags)
 453
 454 #define blk_fs_request(rq)      ((rq)->flags & REQ_CMD)
 455 #define blk_pc_request(rq)      ((rq)->flags & REQ_BLOCK_PC)
 456 #define blk_noretry_request(rq) ((rq)->flags & REQ_FAILFAST)
 457 #define blk_rq_started(rq)      ((rq)->flags & REQ_STARTED)
 458
 459 #define blk_account_rq(rq)      (blk_rq_started(rq) && blk_fs_request(rq))
 460
 461 #define blk_pm_suspend_request(rq)      ((rq)->flags & REQ_PM_SUSPEND)
 462 #define blk_pm_resume_request(rq)       ((rq)->flags & REQ_PM_RESUME)
 463 #define blk_pm_request(rq)      \
 464         ((rq)->flags & (REQ_PM_SUSPEND | REQ_PM_RESUME))
 465
 466 #define blk_sorted_rq(rq)       ((rq)->flags & REQ_SORTED)
 467 #define blk_barrier_rq(rq)      ((rq)->flags & REQ_HARDBARRIER)
 468 #define blk_barrier_preflush(rq)        ((rq)->flags & REQ_BAR_PREFLUSH)
 469 #define blk_barrier_postflush(rq)       ((rq)->flags & REQ_BAR_POSTFLUSH)
 470
 471 #define list_entry_rq(ptr)      list_entry((ptr), struct request, queuelist)
 472
 473 #define rq_data_dir(rq)         ((rq)->flags & 1)
 474
 475 static inline int blk_queue_full(struct request_queue *q, int rw)
 476 {
 477         if (rw == READ)
 478                 return test_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 479         return test_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 480 }
 481
 482 static inline void blk_set_queue_full(struct request_queue *q, int rw)
 483 {
 484         if (rw == READ)
 485                 set_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 486         else
 487                 set_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 488 }
 489
 490 static inline void blk_clear_queue_full(struct request_queue *q, int rw)
 491 {
 492         if (rw == READ)
 493                 clear_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 494         else
 495                 clear_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 496 }
 497
 498
 499 /*
 500  * mergeable request must not have _NOMERGE or _BARRIER bit set, nor may
 501  * it already be started by driver.
 502  */
 503 #define RQ_NOMERGE_FLAGS        \
 504         (REQ_NOMERGE | REQ_STARTED | REQ_HARDBARRIER | REQ_SOFTBARRIER)
 505 #define rq_mergeable(rq)        \
 506         (!((rq)->flags & RQ_NOMERGE_FLAGS) && blk_fs_request((rq)))
 507
 508 /*
 509  * noop, requests are automagically marked as active/inactive by I/O
 510  * scheduler -- see elv_next_request
 511  */
 512 #define blk_queue_headactive(q, head_active)
 513
 514 /*
 515  * q->prep_rq_fn return values
 516  */
 517 #define BLKPREP_OK              0       /* serve it */
 518 #define BLKPREP_KILL            1       /* fatal error, kill */
 519 #define BLKPREP_DEFER           2       /* leave on queue */
 520
 521 extern unsigned long blk_max_low_pfn, blk_max_pfn;
 522
 523 /*
 524  * standard bounce addresses:
 525  *
 526  * BLK_BOUNCE_HIGH      : bounce all highmem pages
 527  * BLK_BOUNCE_ANY       : don't bounce anything
 528  * BLK_BOUNCE_ISA       : bounce pages above ISA DMA boundary
 529  */
 530 #define BLK_BOUNCE_HIGH         ((u64)blk_max_low_pfn << PAGE_SHIFT)
 531 #define BLK_BOUNCE_ANY          ((u64)blk_max_pfn << PAGE_SHIFT)
 532 #define BLK_BOUNCE_ISA          (ISA_DMA_THRESHOLD)
 533
 534 #ifdef CONFIG_MMU
 535 extern int init_emergency_isa_pool(void);
 536 extern void blk_queue_bounce(request_queue_t *q, struct bio **bio);
 537 #else
 538 static inline int init_emergency_isa_pool(void)
 539 {
 540         return 0;
 541 }
 542 static inline void blk_queue_bounce(request_queue_t *q, struct bio **bio)
 543 {
 544 }
 545 #endif /* CONFIG_MMU */
 546
 547 #define rq_for_each_bio(_bio, rq)       \
 548         if ((rq->bio))                  \
 549                 for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)
 550
 551 struct sec_size {
 552         unsigned block_size;
 553         unsigned block_size_bits;
 554 };
 555
 556 extern int blk_register_queue(struct gendisk *disk);
 557 extern void blk_unregister_queue(struct gendisk *disk);
 558 extern void register_disk(struct gendisk *dev);
 559 extern void generic_make_request(struct bio *bio);
 560 extern void blk_put_request(struct request *);
 561 extern void blk_end_sync_rq(struct request *rq);
 562 extern void blk_attempt_remerge(request_queue_t *, struct request *);
 563 extern struct request *blk_get_request(request_queue_t *, int, int);
 564 extern void blk_insert_request(request_queue_t *, struct request *, int, void *);
 565 extern void blk_requeue_request(request_queue_t *, struct request *);
 566 extern void blk_plug_device(request_queue_t *);
 567 extern int blk_remove_plug(request_queue_t *);
 568 extern void blk_recount_segments(request_queue_t *, struct bio *);
 569 extern int scsi_cmd_ioctl(struct file *, struct gendisk *, unsigned int, void __user *);
 570 extern void blk_start_queue(request_queue_t *q);
 571 extern void blk_stop_queue(request_queue_t *q);
 572 extern void blk_sync_queue(struct request_queue *q);
 573 extern void __blk_stop_queue(request_queue_t *q);
 574 extern void blk_run_queue(request_queue_t *);
 575 extern void blk_queue_activity_fn(request_queue_t *, activity_fn *, void *);
 576 extern int blk_rq_map_user(request_queue_t *, struct request *, void __user *, unsigned int);
 577 extern int blk_rq_unmap_user(struct bio *, unsigned int);
 578 extern int blk_rq_map_kern(request_queue_t *, struct request *, void *, unsigned int, unsigned int);
 579 extern int blk_rq_map_user_iov(request_queue_t *, struct request *, struct sg_iovec *, int);
 580 extern int blk_execute_rq(request_queue_t *, struct gendisk *,
 581                           struct request *, int);
 582 static inline request_queue_t *bdev_get_queue(struct block_device *bdev)
 583 {
 584         return bdev->bd_disk->queue;
 585 }
 586
 587 static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
 588                                        struct page *page)
 589 {
 590         if (bdi && bdi->unplug_io_fn)
 591                 bdi->unplug_io_fn(bdi, page);
 592 }
 593
 594 static inline void blk_run_address_space(struct address_space *mapping)
 595 {
 596         if (mapping)
 597                 blk_run_backing_dev(mapping->backing_dev_info, NULL);
 598 }
 599
 600 /*
 601  * end_request() and friends. Must be called with the request queue spinlock
 602  * acquired. All functions called within end_request() _must_be_ atomic.
 603  *
 604  * Several drivers define their own end_request and call
 605  * end_that_request_first() and end_that_request_last()
 606  * for parts of the original function. This prevents
 607  * code duplication in drivers.
 608  */
 609 extern int end_that_request_first(struct request *, int, int);
 610 extern int end_that_request_chunk(struct request *, int, int);
 611 extern void end_that_request_last(struct request *);
 612 extern void end_request(struct request *req, int uptodate);
 613
 614 /*
 615  * end_that_request_first/chunk() takes an uptodate argument. we account
 616  * any value <= as an io error. 0 means -EIO for compatability reasons,
 617  * any other < 0 value is the direct error type. An uptodate value of
 618  * 1 indicates successful io completion
 619  */
 620 #define end_io_error(uptodate)  (unlikely((uptodate) <= 0))
 621
 622 static inline void blkdev_dequeue_request(struct request *req)
 623 {
 624         elv_dequeue_request(req->q, req);
 625 }
 626
 627 /*
 628  * This should be in elevator.h, but that requires pulling in rq and q
 629  */
 630 static inline void elv_dispatch_add_tail(struct request_queue *q,
 631                                          struct request *rq)
 632 {
 633         if (q->last_merge == rq)
 634                 q->last_merge = NULL;
 635
 636         q->end_sector = rq_end_sector(rq);
 637         q->boundary_rq = rq;
 638         list_add_tail(&rq->queuelist, &q->queue_head);
 639 }
 640
 641 /*
 642  * Access functions for manipulating queue properties
 643  */
 644 extern request_queue_t *blk_init_queue_node(request_fn_proc *rfn,
 645                                         spinlock_t *lock, int node_id);
 646 extern request_queue_t *blk_init_queue(request_fn_proc *, spinlock_t *);
 647 extern void blk_cleanup_queue(request_queue_t *);
 648 extern void blk_queue_make_request(request_queue_t *, make_request_fn *);
 649 extern void blk_queue_bounce_limit(request_queue_t *, u64);
 650 extern void blk_queue_max_sectors(request_queue_t *, unsigned short);
 651 extern void blk_queue_max_phys_segments(request_queue_t *, unsigned short);
 652 extern void blk_queue_max_hw_segments(request_queue_t *, unsigned short);
 653 extern void blk_queue_max_segment_size(request_queue_t *, unsigned int);
 654 extern void blk_queue_hardsect_size(request_queue_t *, unsigned short);
 655 extern void blk_queue_stack_limits(request_queue_t *t, request_queue_t *b);
 656 extern void blk_queue_segment_boundary(request_queue_t *, unsigned long);
 657 extern void blk_queue_prep_rq(request_queue_t *, prep_rq_fn *pfn);
 658 extern void blk_queue_merge_bvec(request_queue_t *, merge_bvec_fn *);
 659 extern void blk_queue_dma_alignment(request_queue_t *, int);
 660 extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);
 661 extern void blk_queue_ordered(request_queue_t *, int);
 662 extern void blk_queue_issue_flush_fn(request_queue_t *, issue_flush_fn *);
 663 extern struct request *blk_start_pre_flush(request_queue_t *,struct request *);
 664 extern int blk_complete_barrier_rq(request_queue_t *, struct request *, int);
 665 extern int blk_complete_barrier_rq_locked(request_queue_t *, struct request *, int);
 666
 667 extern int blk_rq_map_sg(request_queue_t *, struct request *, struct scatterlist *);
 668 extern void blk_dump_rq_flags(struct request *, char *);
 669 extern void generic_unplug_device(request_queue_t *);
 670 extern void __generic_unplug_device(request_queue_t *);
 671 extern long nr_blockdev_pages(void);
 672 extern void blk_wait_queue_drained(request_queue_t *, int);
 673 extern void blk_finish_queue_drain(request_queue_t *);
 674
 675 int blk_get_queue(request_queue_t *);
 676 request_queue_t *blk_alloc_queue(int gfp_mask);
 677 request_queue_t *blk_alloc_queue_node(int,int);
 678 #define blk_put_queue(q) blk_cleanup_queue((q))
 679
 680 /*
 681  * tag stuff
 682  */
 683 #define blk_queue_tag_depth(q)          ((q)->queue_tags->busy)
 684 #define blk_queue_tag_queue(q)          ((q)->queue_tags->busy < (q)->queue_tags->max_depth)
 685 #define blk_rq_tagged(rq)               ((rq)->flags & REQ_QUEUED)
 686 extern int blk_queue_start_tag(request_queue_t *, struct request *);
 687 extern struct request *blk_queue_find_tag(request_queue_t *, int);
 688 extern void blk_queue_end_tag(request_queue_t *, struct request *);
 689 extern int blk_queue_init_tags(request_queue_t *, int, struct blk_queue_tag *);
 690 extern void blk_queue_free_tags(request_queue_t *);
 691 extern int blk_queue_resize_tags(request_queue_t *, int);
 692 extern void blk_queue_invalidate_tags(request_queue_t *);
 693 extern long blk_congestion_wait(int rw, long timeout);
 694
 695 extern void blk_rq_bio_prep(request_queue_t *, struct request *, struct bio *);
 696 extern int blkdev_issue_flush(struct block_device *, sector_t *);
 697
 698 #define MAX_PHYS_SEGMENTS 128
 699 #define MAX_HW_SEGMENTS 128
 700 #define MAX_SECTORS 255
 701
 702 #define MAX_SEGMENT_SIZE        65536
 703
 704 #define blkdev_entry_to_request(entry) list_entry((entry), struct request, queuelist)
 705
 706 static inline int queue_hardsect_size(request_queue_t *q)
 707 {
 708         int retval = 512;
 709
 710         if (q && q->hardsect_size)
 711                 retval = q->hardsect_size;
 712
 713         return retval;
 714 }
 715
 716 static inline int bdev_hardsect_size(struct block_device *bdev)
 717 {
 718         return queue_hardsect_size(bdev_get_queue(bdev));
 719 }
 720
 721 static inline int queue_dma_alignment(request_queue_t *q)
 722 {
 723         int retval = 511;
 724
 725         if (q && q->dma_alignment)
 726                 retval = q->dma_alignment;
 727
 728         return retval;
 729 }
 730
 731 static inline int bdev_dma_aligment(struct block_device *bdev)
 732 {
 733         return queue_dma_alignment(bdev_get_queue(bdev));
 734 }
 735
 736 #define blk_finished_io(nsects) do { } while (0)
 737 #define blk_started_io(nsects)  do { } while (0)
 738
 739 /* assumes size > 256 */
 740 static inline unsigned int blksize_bits(unsigned int size)
 741 {
 742         unsigned int bits = 8;
 743         do {
 744                 bits++;
 745                 size >>= 1;
 746         } while (size > 256);
 747         return bits;
 748 }
 749
 750 static inline unsigned int block_size(struct block_device *bdev)
 751 {
 752         return bdev->bd_block_size;
 753 }
 754
 755 typedef struct {struct page *v;} Sector;
 756
 757 unsigned char *read_dev_sector(struct block_device *, sector_t, Sector *);
 758
 759 static inline void put_dev_sector(Sector p)
 760 {
 761         page_cache_release(p.v);
 762 }
 763
 764 struct work_struct;
 765 int kblockd_schedule_work(struct work_struct *work);
 766 void kblockd_flush(void);
 767
 768 #ifdef CONFIG_LBD
 769 # include <asm/div64.h>
 770 # define sector_div(a, b) do_div(a, b)
 771 #else
 772 # define sector_div(n, b)( \
 773 { \
 774         int _res; \
 775         _res = (n) % (b); \
 776         (n) /= (b); \
 777         _res; \
 778 } \
 779 )
 780 #endif
 781
 782 #define MODULE_ALIAS_BLOCKDEV(major,minor) \
 783         MODULE_ALIAS("block-major-" __stringify(major) "-" __stringify(minor))
 784 #define MODULE_ALIAS_BLOCKDEV_MAJOR(major) \
 785         MODULE_ALIAS("block-major-" __stringify(major) "-*")
 786
 787
 788 #endif