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