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_SOFTBARRIER,      /* may not be passed by ioscheduler */
 207         __REQ_HARDBARRIER,      /* may not be passed by drive either */
 208         __REQ_CMD,              /* is a regular fs rw request */
 209         __REQ_NOMERGE,          /* don't touch this for merging */
 210         __REQ_STARTED,          /* drive already may have started this one */
 211         __REQ_DONTPREP,         /* don't call prep for this one */
 212         __REQ_QUEUED,           /* uses queueing */
 213         /*
 214          * for ATA/ATAPI devices
 215          */
 216         __REQ_PC,               /* packet command (special) */
 217         __REQ_BLOCK_PC,         /* queued down pc from block layer */
 218         __REQ_SENSE,            /* sense retrival */
 219
 220         __REQ_FAILED,           /* set if the request failed */
 221         __REQ_QUIET,            /* don't worry about errors */
 222         __REQ_SPECIAL,          /* driver suplied command */
 223         __REQ_DRIVE_CMD,
 224         __REQ_DRIVE_TASK,
 225         __REQ_DRIVE_TASKFILE,
 226         __REQ_PREEMPT,          /* set for "ide_preempt" requests */
 227         __REQ_PM_SUSPEND,       /* suspend request */
 228         __REQ_PM_RESUME,        /* resume request */
 229         __REQ_PM_SHUTDOWN,      /* shutdown request */
 230         __REQ_BAR_PREFLUSH,     /* barrier pre-flush done */
 231         __REQ_BAR_POSTFLUSH,    /* barrier post-flush */
 232         __REQ_BAR_FLUSH,        /* rq is the flush request */
 233         __REQ_NR_BITS,          /* stops here */
 234 };
 235
 236 #define REQ_RW          (1 << __REQ_RW)
 237 #define REQ_FAILFAST    (1 << __REQ_FAILFAST)
 238 #define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER)
 239 #define REQ_HARDBARRIER (1 << __REQ_HARDBARRIER)
 240 #define REQ_CMD         (1 << __REQ_CMD)
 241 #define REQ_NOMERGE     (1 << __REQ_NOMERGE)
 242 #define REQ_STARTED     (1 << __REQ_STARTED)
 243 #define REQ_DONTPREP    (1 << __REQ_DONTPREP)
 244 #define REQ_QUEUED      (1 << __REQ_QUEUED)
 245 #define REQ_PC          (1 << __REQ_PC)
 246 #define REQ_BLOCK_PC    (1 << __REQ_BLOCK_PC)
 247 #define REQ_SENSE       (1 << __REQ_SENSE)
 248 #define REQ_FAILED      (1 << __REQ_FAILED)
 249 #define REQ_QUIET       (1 << __REQ_QUIET)
 250 #define REQ_SPECIAL     (1 << __REQ_SPECIAL)
 251 #define REQ_DRIVE_CMD   (1 << __REQ_DRIVE_CMD)
 252 #define REQ_DRIVE_TASK  (1 << __REQ_DRIVE_TASK)
 253 #define REQ_DRIVE_TASKFILE      (1 << __REQ_DRIVE_TASKFILE)
 254 #define REQ_PREEMPT     (1 << __REQ_PREEMPT)
 255 #define REQ_PM_SUSPEND  (1 << __REQ_PM_SUSPEND)
 256 #define REQ_PM_RESUME   (1 << __REQ_PM_RESUME)
 257 #define REQ_PM_SHUTDOWN (1 << __REQ_PM_SHUTDOWN)
 258 #define REQ_BAR_PREFLUSH        (1 << __REQ_BAR_PREFLUSH)
 259 #define REQ_BAR_POSTFLUSH       (1 << __REQ_BAR_POSTFLUSH)
 260 #define REQ_BAR_FLUSH   (1 << __REQ_BAR_FLUSH)
 261
 262 /*
 263  * State information carried for REQ_PM_SUSPEND and REQ_PM_RESUME
 264  * requests. Some step values could eventually be made generic.
 265  */
 266 struct request_pm_state
 267 {
 268         /* PM state machine step value, currently driver specific */
 269         int     pm_step;
 270         /* requested PM state value (S1, S2, S3, S4, ...) */
 271         u32     pm_state;
 272         void*   data;           /* for driver use */
 273 };
 274
 275 #include <linux/elevator.h>
 276
 277 typedef int (merge_request_fn) (request_queue_t *, struct request *,
 278                                 struct bio *);
 279 typedef int (merge_requests_fn) (request_queue_t *, struct request *,
 280                                  struct request *);
 281 typedef void (request_fn_proc) (request_queue_t *q);
 282 typedef int (make_request_fn) (request_queue_t *q, struct bio *bio);
 283 typedef int (prep_rq_fn) (request_queue_t *, struct request *);
 284 typedef void (unplug_fn) (request_queue_t *);
 285
 286 struct bio_vec;
 287 typedef int (merge_bvec_fn) (request_queue_t *, struct bio *, struct bio_vec *);
 288 typedef void (activity_fn) (void *data, int rw);
 289 typedef int (issue_flush_fn) (request_queue_t *, struct gendisk *, sector_t *);
 290 typedef int (prepare_flush_fn) (request_queue_t *, struct request *);
 291 typedef void (end_flush_fn) (request_queue_t *, struct request *);
 292
 293 enum blk_queue_state {
 294         Queue_down,
 295         Queue_up,
 296 };
 297
 298 struct blk_queue_tag {
 299         struct request **tag_index;     /* map of busy tags */
 300         unsigned long *tag_map;         /* bit map of free/busy tags */
 301         struct list_head busy_list;     /* fifo list of busy tags */
 302         int busy;                       /* current depth */
 303         int max_depth;                  /* what we will send to device */
 304         int real_max_depth;             /* what the array can hold */
 305         atomic_t refcnt;                /* map can be shared */
 306 };
 307
 308 struct request_queue
 309 {
 310         /*
 311          * Together with queue_head for cacheline sharing
 312          */
 313         struct list_head        queue_head;
 314         struct request          *last_merge;
 315         elevator_t              *elevator;
 316
 317         /*
 318          * the queue request freelist, one for reads and one for writes
 319          */
 320         struct request_list     rq;
 321
 322         request_fn_proc         *request_fn;
 323         merge_request_fn        *back_merge_fn;
 324         merge_request_fn        *front_merge_fn;
 325         merge_requests_fn       *merge_requests_fn;
 326         make_request_fn         *make_request_fn;
 327         prep_rq_fn              *prep_rq_fn;
 328         unplug_fn               *unplug_fn;
 329         merge_bvec_fn           *merge_bvec_fn;
 330         activity_fn             *activity_fn;
 331         issue_flush_fn          *issue_flush_fn;
 332         prepare_flush_fn        *prepare_flush_fn;
 333         end_flush_fn            *end_flush_fn;
 334
 335         /*
 336          * Auto-unplugging state
 337          */
 338         struct timer_list       unplug_timer;
 339         int                     unplug_thresh;  /* After this many requests */
 340         unsigned long           unplug_delay;   /* After this many jiffies */
 341         struct work_struct      unplug_work;
 342
 343         struct backing_dev_info backing_dev_info;
 344
 345         /*
 346          * The queue owner gets to use this for whatever they like.
 347          * ll_rw_blk doesn't touch it.
 348          */
 349         void                    *queuedata;
 350
 351         void                    *activity_data;
 352
 353         /*
 354          * queue needs bounce pages for pages above this limit
 355          */
 356         unsigned long           bounce_pfn;
 357         unsigned int            bounce_gfp;
 358
 359         /*
 360          * various queue flags, see QUEUE_* below
 361          */
 362         unsigned long           queue_flags;
 363
 364         /*
 365          * protects queue structures from reentrancy. ->__queue_lock should
 366          * _never_ be used directly, it is queue private. always use
 367          * ->queue_lock.
 368          */
 369         spinlock_t              __queue_lock;
 370         spinlock_t              *queue_lock;
 371
 372         /*
 373          * queue kobject
 374          */
 375         struct kobject kobj;
 376
 377         /*
 378          * queue settings
 379          */
 380         unsigned long           nr_requests;    /* Max # of requests */
 381         unsigned int            nr_congestion_on;
 382         unsigned int            nr_congestion_off;
 383         unsigned int            nr_batching;
 384
 385         unsigned short          max_sectors;
 386         unsigned short          max_hw_sectors;
 387         unsigned short          max_phys_segments;
 388         unsigned short          max_hw_segments;
 389         unsigned short          hardsect_size;
 390         unsigned int            max_segment_size;
 391
 392         unsigned long           seg_boundary_mask;
 393         unsigned int            dma_alignment;
 394
 395         struct blk_queue_tag    *queue_tags;
 396
 397         atomic_t                refcnt;
 398
 399         unsigned int            in_flight;
 400
 401         /*
 402          * sg stuff
 403          */
 404         unsigned int            sg_timeout;
 405         unsigned int            sg_reserved_size;
 406         int                     node;
 407
 408         struct list_head        drain_list;
 409
 410         /*
 411          * reserved for flush operations
 412          */
 413         struct request          *flush_rq;
 414         unsigned char           ordered;
 415 };
 416
 417 enum {
 418         QUEUE_ORDERED_NONE,
 419         QUEUE_ORDERED_TAG,
 420         QUEUE_ORDERED_FLUSH,
 421 };
 422
 423 #define RQ_INACTIVE             (-1)
 424 #define RQ_ACTIVE               1
 425 #define RQ_SCSI_BUSY            0xffff
 426 #define RQ_SCSI_DONE            0xfffe
 427 #define RQ_SCSI_DISCONNECTING   0xffe0
 428
 429 #define QUEUE_FLAG_CLUSTER      0       /* cluster several segments into 1 */
 430 #define QUEUE_FLAG_QUEUED       1       /* uses generic tag queueing */
 431 #define QUEUE_FLAG_STOPPED      2       /* queue is stopped */
 432 #define QUEUE_FLAG_READFULL     3       /* write queue has been filled */
 433 #define QUEUE_FLAG_WRITEFULL    4       /* read queue has been filled */
 434 #define QUEUE_FLAG_DEAD         5       /* queue being torn down */
 435 #define QUEUE_FLAG_REENTER      6       /* Re-entrancy avoidance */
 436 #define QUEUE_FLAG_PLUGGED      7       /* queue is plugged */
 437 #define QUEUE_FLAG_DRAIN        8       /* draining queue for sched switch */
 438 #define QUEUE_FLAG_FLUSH        9       /* doing barrier flush sequence */
 439
 440 #define blk_queue_plugged(q)    test_bit(QUEUE_FLAG_PLUGGED, &(q)->queue_flags)
 441 #define blk_queue_tagged(q)     test_bit(QUEUE_FLAG_QUEUED, &(q)->queue_flags)
 442 #define blk_queue_stopped(q)    test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
 443 #define blk_queue_flushing(q)   test_bit(QUEUE_FLAG_FLUSH, &(q)->queue_flags)
 444
 445 #define blk_fs_request(rq)      ((rq)->flags & REQ_CMD)
 446 #define blk_pc_request(rq)      ((rq)->flags & REQ_BLOCK_PC)
 447 #define blk_noretry_request(rq) ((rq)->flags & REQ_FAILFAST)
 448 #define blk_rq_started(rq)      ((rq)->flags & REQ_STARTED)
 449
 450 #define blk_account_rq(rq)      (blk_rq_started(rq) && blk_fs_request(rq))
 451
 452 #define blk_pm_suspend_request(rq)      ((rq)->flags & REQ_PM_SUSPEND)
 453 #define blk_pm_resume_request(rq)       ((rq)->flags & REQ_PM_RESUME)
 454 #define blk_pm_request(rq)      \
 455         ((rq)->flags & (REQ_PM_SUSPEND | REQ_PM_RESUME))
 456
 457 #define blk_barrier_rq(rq)      ((rq)->flags & REQ_HARDBARRIER)
 458 #define blk_barrier_preflush(rq)        ((rq)->flags & REQ_BAR_PREFLUSH)
 459 #define blk_barrier_postflush(rq)       ((rq)->flags & REQ_BAR_POSTFLUSH)
 460
 461 #define list_entry_rq(ptr)      list_entry((ptr), struct request, queuelist)
 462
 463 #define rq_data_dir(rq)         ((rq)->flags & 1)
 464
 465 static inline int blk_queue_full(struct request_queue *q, int rw)
 466 {
 467         if (rw == READ)
 468                 return test_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 469         return test_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 470 }
 471
 472 static inline void blk_set_queue_full(struct request_queue *q, int rw)
 473 {
 474         if (rw == READ)
 475                 set_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 476         else
 477                 set_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 478 }
 479
 480 static inline void blk_clear_queue_full(struct request_queue *q, int rw)
 481 {
 482         if (rw == READ)
 483                 clear_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 484         else
 485                 clear_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 486 }
 487
 488
 489 /*
 490  * mergeable request must not have _NOMERGE or _BARRIER bit set, nor may
 491  * it already be started by driver.
 492  */
 493 #define RQ_NOMERGE_FLAGS        \
 494         (REQ_NOMERGE | REQ_STARTED | REQ_HARDBARRIER | REQ_SOFTBARRIER)
 495 #define rq_mergeable(rq)        \
 496         (!((rq)->flags & RQ_NOMERGE_FLAGS) && blk_fs_request((rq)))
 497
 498 /*
 499  * noop, requests are automagically marked as active/inactive by I/O
 500  * scheduler -- see elv_next_request
 501  */
 502 #define blk_queue_headactive(q, head_active)
 503
 504 /*
 505  * q->prep_rq_fn return values
 506  */
 507 #define BLKPREP_OK              0       /* serve it */
 508 #define BLKPREP_KILL            1       /* fatal error, kill */
 509 #define BLKPREP_DEFER           2       /* leave on queue */
 510
 511 extern unsigned long blk_max_low_pfn, blk_max_pfn;
 512
 513 /*
 514  * standard bounce addresses:
 515  *
 516  * BLK_BOUNCE_HIGH      : bounce all highmem pages
 517  * BLK_BOUNCE_ANY       : don't bounce anything
 518  * BLK_BOUNCE_ISA       : bounce pages above ISA DMA boundary
 519  */
 520 #define BLK_BOUNCE_HIGH         ((u64)blk_max_low_pfn << PAGE_SHIFT)
 521 #define BLK_BOUNCE_ANY          ((u64)blk_max_pfn << PAGE_SHIFT)
 522 #define BLK_BOUNCE_ISA          (ISA_DMA_THRESHOLD)
 523
 524 #ifdef CONFIG_MMU
 525 extern int init_emergency_isa_pool(void);
 526 extern void blk_queue_bounce(request_queue_t *q, struct bio **bio);
 527 #else
 528 static inline int init_emergency_isa_pool(void)
 529 {
 530         return 0;
 531 }
 532 static inline void blk_queue_bounce(request_queue_t *q, struct bio **bio)
 533 {
 534 }
 535 #endif /* CONFIG_MMU */
 536
 537 #define rq_for_each_bio(_bio, rq)       \
 538         if ((rq->bio))                  \
 539                 for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)
 540
 541 struct sec_size {
 542         unsigned block_size;
 543         unsigned block_size_bits;
 544 };
 545
 546 extern int blk_register_queue(struct gendisk *disk);
 547 extern void blk_unregister_queue(struct gendisk *disk);
 548 extern void register_disk(struct gendisk *dev);
 549 extern void generic_make_request(struct bio *bio);
 550 extern void blk_put_request(struct request *);
 551 extern void blk_end_sync_rq(struct request *rq);
 552 extern void blk_attempt_remerge(request_queue_t *, struct request *);
 553 extern struct request *blk_get_request(request_queue_t *, int, int);
 554 extern void blk_insert_request(request_queue_t *, struct request *, int, void *);
 555 extern void blk_requeue_request(request_queue_t *, struct request *);
 556 extern void blk_plug_device(request_queue_t *);
 557 extern int blk_remove_plug(request_queue_t *);
 558 extern void blk_recount_segments(request_queue_t *, struct bio *);
 559 extern int scsi_cmd_ioctl(struct file *, struct gendisk *, unsigned int, void __user *);
 560 extern void blk_start_queue(request_queue_t *q);
 561 extern void blk_stop_queue(request_queue_t *q);
 562 extern void blk_sync_queue(struct request_queue *q);
 563 extern void __blk_stop_queue(request_queue_t *q);
 564 extern void blk_run_queue(request_queue_t *);
 565 extern void blk_queue_activity_fn(request_queue_t *, activity_fn *, void *);
 566 extern int blk_rq_map_user(request_queue_t *, struct request *, void __user *, unsigned int);
 567 extern int blk_rq_unmap_user(struct bio *, unsigned int);
 568 extern int blk_rq_map_kern(request_queue_t *, struct request *, void *, unsigned int, unsigned int);
 569 extern int blk_rq_map_user_iov(request_queue_t *, struct request *, struct sg_iovec *, int);
 570 extern int blk_execute_rq(request_queue_t *, struct gendisk *,
 571                           struct request *, int);
 572 static inline request_queue_t *bdev_get_queue(struct block_device *bdev)
 573 {
 574         return bdev->bd_disk->queue;
 575 }
 576
 577 static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
 578                                        struct page *page)
 579 {
 580         if (bdi && bdi->unplug_io_fn)
 581                 bdi->unplug_io_fn(bdi, page);
 582 }
 583
 584 static inline void blk_run_address_space(struct address_space *mapping)
 585 {
 586         if (mapping)
 587                 blk_run_backing_dev(mapping->backing_dev_info, NULL);
 588 }
 589
 590 /*
 591  * end_request() and friends. Must be called with the request queue spinlock
 592  * acquired. All functions called within end_request() _must_be_ atomic.
 593  *
 594  * Several drivers define their own end_request and call
 595  * end_that_request_first() and end_that_request_last()
 596  * for parts of the original function. This prevents
 597  * code duplication in drivers.
 598  */
 599 extern int end_that_request_first(struct request *, int, int);
 600 extern int end_that_request_chunk(struct request *, int, int);
 601 extern void end_that_request_last(struct request *);
 602 extern void end_request(struct request *req, int uptodate);
 603
 604 /*
 605  * end_that_request_first/chunk() takes an uptodate argument. we account
 606  * any value <= as an io error. 0 means -EIO for compatability reasons,
 607  * any other < 0 value is the direct error type. An uptodate value of
 608  * 1 indicates successful io completion
 609  */
 610 #define end_io_error(uptodate)  (unlikely((uptodate) <= 0))
 611
 612 static inline void blkdev_dequeue_request(struct request *req)
 613 {
 614         BUG_ON(list_empty(&req->queuelist));
 615
 616         list_del_init(&req->queuelist);
 617
 618         if (req->rl)
 619                 elv_remove_request(req->q, req);
 620 }
 621
 622 /*
 623  * Access functions for manipulating queue properties
 624  */
 625 extern request_queue_t *blk_init_queue_node(request_fn_proc *rfn,
 626                                         spinlock_t *lock, int node_id);
 627 extern request_queue_t *blk_init_queue(request_fn_proc *, spinlock_t *);
 628 extern void blk_cleanup_queue(request_queue_t *);
 629 extern void blk_queue_make_request(request_queue_t *, make_request_fn *);
 630 extern void blk_queue_bounce_limit(request_queue_t *, u64);
 631 extern void blk_queue_max_sectors(request_queue_t *, unsigned short);
 632 extern void blk_queue_max_phys_segments(request_queue_t *, unsigned short);
 633 extern void blk_queue_max_hw_segments(request_queue_t *, unsigned short);
 634 extern void blk_queue_max_segment_size(request_queue_t *, unsigned int);
 635 extern void blk_queue_hardsect_size(request_queue_t *, unsigned short);
 636 extern void blk_queue_stack_limits(request_queue_t *t, request_queue_t *b);
 637 extern void blk_queue_segment_boundary(request_queue_t *, unsigned long);
 638 extern void blk_queue_prep_rq(request_queue_t *, prep_rq_fn *pfn);
 639 extern void blk_queue_merge_bvec(request_queue_t *, merge_bvec_fn *);
 640 extern void blk_queue_dma_alignment(request_queue_t *, int);
 641 extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);
 642 extern void blk_queue_ordered(request_queue_t *, int);
 643 extern void blk_queue_issue_flush_fn(request_queue_t *, issue_flush_fn *);
 644 extern struct request *blk_start_pre_flush(request_queue_t *,struct request *);
 645 extern int blk_complete_barrier_rq(request_queue_t *, struct request *, int);
 646 extern int blk_complete_barrier_rq_locked(request_queue_t *, struct request *, int);
 647
 648 extern int blk_rq_map_sg(request_queue_t *, struct request *, struct scatterlist *);
 649 extern void blk_dump_rq_flags(struct request *, char *);
 650 extern void generic_unplug_device(request_queue_t *);
 651 extern void __generic_unplug_device(request_queue_t *);
 652 extern long nr_blockdev_pages(void);
 653 extern void blk_wait_queue_drained(request_queue_t *, int);
 654 extern void blk_finish_queue_drain(request_queue_t *);
 655
 656 int blk_get_queue(request_queue_t *);
 657 request_queue_t *blk_alloc_queue(int gfp_mask);
 658 request_queue_t *blk_alloc_queue_node(int,int);
 659 #define blk_put_queue(q) blk_cleanup_queue((q))
 660
 661 /*
 662  * tag stuff
 663  */
 664 #define blk_queue_tag_depth(q)          ((q)->queue_tags->busy)
 665 #define blk_queue_tag_queue(q)          ((q)->queue_tags->busy < (q)->queue_tags->max_depth)
 666 #define blk_rq_tagged(rq)               ((rq)->flags & REQ_QUEUED)
 667 extern int blk_queue_start_tag(request_queue_t *, struct request *);
 668 extern struct request *blk_queue_find_tag(request_queue_t *, int);
 669 extern void blk_queue_end_tag(request_queue_t *, struct request *);
 670 extern int blk_queue_init_tags(request_queue_t *, int, struct blk_queue_tag *);
 671 extern void blk_queue_free_tags(request_queue_t *);
 672 extern int blk_queue_resize_tags(request_queue_t *, int);
 673 extern void blk_queue_invalidate_tags(request_queue_t *);
 674 extern long blk_congestion_wait(int rw, long timeout);
 675
 676 extern void blk_rq_bio_prep(request_queue_t *, struct request *, struct bio *);
 677 extern int blkdev_issue_flush(struct block_device *, sector_t *);
 678
 679 #define MAX_PHYS_SEGMENTS 128
 680 #define MAX_HW_SEGMENTS 128
 681 #define MAX_SECTORS 255
 682
 683 #define MAX_SEGMENT_SIZE        65536
 684
 685 #define blkdev_entry_to_request(entry) list_entry((entry), struct request, queuelist)
 686
 687 static inline int queue_hardsect_size(request_queue_t *q)
 688 {
 689         int retval = 512;
 690
 691         if (q && q->hardsect_size)
 692                 retval = q->hardsect_size;
 693
 694         return retval;
 695 }
 696
 697 static inline int bdev_hardsect_size(struct block_device *bdev)
 698 {
 699         return queue_hardsect_size(bdev_get_queue(bdev));
 700 }
 701
 702 static inline int queue_dma_alignment(request_queue_t *q)
 703 {
 704         int retval = 511;
 705
 706         if (q && q->dma_alignment)
 707                 retval = q->dma_alignment;
 708
 709         return retval;
 710 }
 711
 712 static inline int bdev_dma_aligment(struct block_device *bdev)
 713 {
 714         return queue_dma_alignment(bdev_get_queue(bdev));
 715 }
 716
 717 #define blk_finished_io(nsects) do { } while (0)
 718 #define blk_started_io(nsects)  do { } while (0)
 719
 720 /* assumes size > 256 */
 721 static inline unsigned int blksize_bits(unsigned int size)
 722 {
 723         unsigned int bits = 8;
 724         do {
 725                 bits++;
 726                 size >>= 1;
 727         } while (size > 256);
 728         return bits;
 729 }
 730
 731 extern inline unsigned int block_size(struct block_device *bdev)
 732 {
 733         return bdev->bd_block_size;
 734 }
 735
 736 typedef struct {struct page *v;} Sector;
 737
 738 unsigned char *read_dev_sector(struct block_device *, sector_t, Sector *);
 739
 740 static inline void put_dev_sector(Sector p)
 741 {
 742         page_cache_release(p.v);
 743 }
 744
 745 struct work_struct;
 746 int kblockd_schedule_work(struct work_struct *work);
 747 void kblockd_flush(void);
 748
 749 #ifdef CONFIG_LBD
 750 # include <asm/div64.h>
 751 # define sector_div(a, b) do_div(a, b)
 752 #else
 753 # define sector_div(n, b)( \
 754 { \
 755         int _res; \
 756         _res = (n) % (b); \
 757         (n) /= (b); \
 758         _res; \
 759 } \
 760 )
 761 #endif
 762
 763 #define MODULE_ALIAS_BLOCKDEV(major,minor) \
 764         MODULE_ALIAS("block-major-" __stringify(major) "-" __stringify(minor))
 765 #define MODULE_ALIAS_BLOCKDEV_MAJOR(major) \
 766         MODULE_ALIAS("block-major-" __stringify(major) "-*")
 767
 768
 769 #endif