include/linux/blkdev.h

   1 #ifndef _LINUX_BLKDEV_H
   2 #define _LINUX_BLKDEV_H
   3
   4 #include <linux/major.h>
   5 #include <linux/genhd.h>
   6 #include <linux/list.h>
   7 #include <linux/timer.h>
   8 #include <linux/workqueue.h>
   9 #include <linux/pagemap.h>
  10 #include <linux/backing-dev.h>
  11 #include <linux/wait.h>
  12 #include <linux/mempool.h>
  13 #include <linux/bio.h>
  14 #include <linux/module.h>
  15 #include <linux/stringify.h>
  16
  17 #include <asm/scatterlist.h>
  18
  19 struct scsi_ioctl_command;
  20
  21 struct request_queue;
  22 typedef struct request_queue request_queue_t;
  23 struct elevator_queue;
  24 typedef struct elevator_queue elevator_t;
  25 struct request_pm_state;
  26 struct blk_trace;
  27
  28 #define BLKDEV_MIN_RQ   4
  29 #define BLKDEV_MAX_RQ   128     /* Default maximum */
  30
  31 /*
  32  * This is the per-process anticipatory I/O scheduler state.
  33  */
  34 struct as_io_context {
  35         spinlock_t lock;
  36
  37         void (*dtor)(struct as_io_context *aic); /* destructor */
  38         void (*exit)(struct as_io_context *aic); /* called on task exit */
  39
  40         unsigned long state;
  41         atomic_t nr_queued; /* queued reads & sync writes */
  42         atomic_t nr_dispatched; /* number of requests gone to the drivers */
  43
  44         /* IO History tracking */
  45         /* Thinktime */
  46         unsigned long last_end_request;
  47         unsigned long ttime_total;
  48         unsigned long ttime_samples;
  49         unsigned long ttime_mean;
  50         /* Layout pattern */
  51         unsigned int seek_samples;
  52         sector_t last_request_pos;
  53         u64 seek_total;
  54         sector_t seek_mean;
  55 };
  56
  57 struct cfq_queue;
  58 struct cfq_io_context {
  59         struct rb_node rb_node;
  60         void *key;
  61
  62         struct cfq_queue *cfqq[2];
  63
  64         struct io_context *ioc;
  65
  66         unsigned long last_end_request;
  67         sector_t last_request_pos;
  68         unsigned long last_queue;
  69
  70         unsigned long ttime_total;
  71         unsigned long ttime_samples;
  72         unsigned long ttime_mean;
  73
  74         unsigned int seek_samples;
  75         u64 seek_total;
  76         sector_t seek_mean;
  77
  78         struct list_head queue_list;
  79
  80         void (*dtor)(struct io_context *); /* destructor */
  81         void (*exit)(struct io_context *); /* called on task exit */
  82 };
  83
  84 /*
  85  * This is the per-process I/O subsystem state.  It is refcounted and
  86  * kmalloc'ed. Currently all fields are modified in process io context
  87  * (apart from the atomic refcount), so require no locking.
  88  */
  89 struct io_context {
  90         atomic_t refcount;
  91         struct task_struct *task;
  92
  93         int (*set_ioprio)(struct io_context *, unsigned int);
  94
  95         /*
  96          * For request batching
  97          */
  98         unsigned long last_waited; /* Time last woken after wait for request */
  99         int nr_batch_requests;     /* Number of requests left in the batch */
 100
 101         struct as_io_context *aic;
 102         struct rb_root cic_root;
 103 };
 104
 105 void put_io_context(struct io_context *ioc);
 106 void exit_io_context(void);
 107 struct io_context *current_io_context(gfp_t gfp_flags);
 108 struct io_context *get_io_context(gfp_t gfp_flags);
 109 void copy_io_context(struct io_context **pdst, struct io_context **psrc);
 110 void swap_io_context(struct io_context **ioc1, struct io_context **ioc2);
 111
 112 struct request;
 113 typedef void (rq_end_io_fn)(struct request *, int);
 114
 115 struct request_list {
 116         int count[2];
 117         int starved[2];
 118         int elvpriv;
 119         mempool_t *rq_pool;
 120         wait_queue_head_t wait[2];
 121 };
 122
 123 #define BLK_MAX_CDB     16
 124
 125 /*
 126  * try to put the fields that are referenced together in the same cacheline
 127  */
 128 struct request {
 129         struct list_head queuelist;
 130         struct list_head donelist;
 131
 132         unsigned long flags;            /* see REQ_ bits below */
 133
 134         /* Maintain bio traversal state for part by part I/O submission.
 135          * hard_* are block layer internals, no driver should touch them!
 136          */
 137
 138         sector_t sector;                /* next sector to submit */
 139         unsigned long nr_sectors;       /* no. of sectors left to submit */
 140         /* no. of sectors left to submit in the current segment */
 141         unsigned int current_nr_sectors;
 142
 143         sector_t hard_sector;           /* next sector to complete */
 144         unsigned long hard_nr_sectors;  /* no. of sectors left to complete */
 145         /* no. of sectors left to complete in the current segment */
 146         unsigned int hard_cur_sectors;
 147
 148         struct bio *bio;
 149         struct bio *biotail;
 150
 151         void *elevator_private;
 152         void *completion_data;
 153
 154         int rq_status;  /* should split this into a few status bits */
 155         int errors;
 156         struct gendisk *rq_disk;
 157         unsigned long start_time;
 158
 159         /* Number of scatter-gather DMA addr+len pairs after
 160          * physical address coalescing is performed.
 161          */
 162         unsigned short nr_phys_segments;
 163
 164         /* Number of scatter-gather addr+len pairs after
 165          * physical and DMA remapping hardware coalescing is performed.
 166          * This is the number of scatter-gather entries the driver
 167          * will actually have to deal with after DMA mapping is done.
 168          */
 169         unsigned short nr_hw_segments;
 170
 171         unsigned short ioprio;
 172
 173         int tag;
 174
 175         int ref_count;
 176         request_queue_t *q;
 177         struct request_list *rl;
 178
 179         struct completion *waiting;
 180         void *special;
 181         char *buffer;
 182
 183         /*
 184          * when request is used as a packet command carrier
 185          */
 186         unsigned int cmd_len;
 187         unsigned char cmd[BLK_MAX_CDB];
 188
 189         unsigned int data_len;
 190         unsigned int sense_len;
 191         void *data;
 192         void *sense;
 193
 194         unsigned int timeout;
 195         int retries;
 196
 197         /*
 198          * completion callback. end_io_data should be folded in with waiting
 199          */
 200         rq_end_io_fn *end_io;
 201         void *end_io_data;
 202 };
 203
 204 /*
 205  * first three bits match BIO_RW* bits, important
 206  */
 207 enum rq_flag_bits {
 208         __REQ_RW,               /* not set, read. set, write */
 209         __REQ_FAILFAST,         /* no low level driver retries */
 210         __REQ_SORTED,           /* elevator knows about this request */
 211         __REQ_SOFTBARRIER,      /* may not be passed by ioscheduler */
 212         __REQ_HARDBARRIER,      /* may not be passed by drive either */
 213         __REQ_FUA,              /* forced unit access */
 214         __REQ_CMD,              /* is a regular fs rw request */
 215         __REQ_NOMERGE,          /* don't touch this for merging */
 216         __REQ_STARTED,          /* drive already may have started this one */
 217         __REQ_DONTPREP,         /* don't call prep for this one */
 218         __REQ_QUEUED,           /* uses queueing */
 219         __REQ_ELVPRIV,          /* elevator private data attached */
 220         /*
 221          * for ATA/ATAPI devices
 222          */
 223         __REQ_PC,               /* packet command (special) */
 224         __REQ_BLOCK_PC,         /* queued down pc from block layer */
 225         __REQ_SENSE,            /* sense retrival */
 226
 227         __REQ_FAILED,           /* set if the request failed */
 228         __REQ_QUIET,            /* don't worry about errors */
 229         __REQ_SPECIAL,          /* driver suplied command */
 230         __REQ_DRIVE_CMD,
 231         __REQ_DRIVE_TASK,
 232         __REQ_DRIVE_TASKFILE,
 233         __REQ_PREEMPT,          /* set for "ide_preempt" requests */
 234         __REQ_PM_SUSPEND,       /* suspend request */
 235         __REQ_PM_RESUME,        /* resume request */
 236         __REQ_PM_SHUTDOWN,      /* shutdown request */
 237         __REQ_ORDERED_COLOR,    /* is before or after barrier */
 238         __REQ_RW_SYNC,          /* request is sync (O_DIRECT) */
 239         __REQ_NR_BITS,          /* stops here */
 240 };
 241
 242 #define REQ_RW          (1 << __REQ_RW)
 243 #define REQ_FAILFAST    (1 << __REQ_FAILFAST)
 244 #define REQ_SORTED      (1 << __REQ_SORTED)
 245 #define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER)
 246 #define REQ_HARDBARRIER (1 << __REQ_HARDBARRIER)
 247 #define REQ_FUA         (1 << __REQ_FUA)
 248 #define REQ_CMD         (1 << __REQ_CMD)
 249 #define REQ_NOMERGE     (1 << __REQ_NOMERGE)
 250 #define REQ_STARTED     (1 << __REQ_STARTED)
 251 #define REQ_DONTPREP    (1 << __REQ_DONTPREP)
 252 #define REQ_QUEUED      (1 << __REQ_QUEUED)
 253 #define REQ_ELVPRIV     (1 << __REQ_ELVPRIV)
 254 #define REQ_PC          (1 << __REQ_PC)
 255 #define REQ_BLOCK_PC    (1 << __REQ_BLOCK_PC)
 256 #define REQ_SENSE       (1 << __REQ_SENSE)
 257 #define REQ_FAILED      (1 << __REQ_FAILED)
 258 #define REQ_QUIET       (1 << __REQ_QUIET)
 259 #define REQ_SPECIAL     (1 << __REQ_SPECIAL)
 260 #define REQ_DRIVE_CMD   (1 << __REQ_DRIVE_CMD)
 261 #define REQ_DRIVE_TASK  (1 << __REQ_DRIVE_TASK)
 262 #define REQ_DRIVE_TASKFILE      (1 << __REQ_DRIVE_TASKFILE)
 263 #define REQ_PREEMPT     (1 << __REQ_PREEMPT)
 264 #define REQ_PM_SUSPEND  (1 << __REQ_PM_SUSPEND)
 265 #define REQ_PM_RESUME   (1 << __REQ_PM_RESUME)
 266 #define REQ_PM_SHUTDOWN (1 << __REQ_PM_SHUTDOWN)
 267 #define REQ_ORDERED_COLOR       (1 << __REQ_ORDERED_COLOR)
 268 #define REQ_RW_SYNC     (1 << __REQ_RW_SYNC)
 269
 270 /*
 271  * State information carried for REQ_PM_SUSPEND and REQ_PM_RESUME
 272  * requests. Some step values could eventually be made generic.
 273  */
 274 struct request_pm_state
 275 {
 276         /* PM state machine step value, currently driver specific */
 277         int     pm_step;
 278         /* requested PM state value (S1, S2, S3, S4, ...) */
 279         u32     pm_state;
 280         void*   data;           /* for driver use */
 281 };
 282
 283 #include <linux/elevator.h>
 284
 285 typedef int (merge_request_fn) (request_queue_t *, struct request *,
 286                                 struct bio *);
 287 typedef int (merge_requests_fn) (request_queue_t *, struct request *,
 288                                  struct request *);
 289 typedef void (request_fn_proc) (request_queue_t *q);
 290 typedef int (make_request_fn) (request_queue_t *q, struct bio *bio);
 291 typedef int (prep_rq_fn) (request_queue_t *, struct request *);
 292 typedef void (unplug_fn) (request_queue_t *);
 293
 294 struct bio_vec;
 295 typedef int (merge_bvec_fn) (request_queue_t *, struct bio *, struct bio_vec *);
 296 typedef void (activity_fn) (void *data, int rw);
 297 typedef int (issue_flush_fn) (request_queue_t *, struct gendisk *, sector_t *);
 298 typedef void (prepare_flush_fn) (request_queue_t *, struct request *);
 299 typedef void (softirq_done_fn)(struct request *);
 300
 301 enum blk_queue_state {
 302         Queue_down,
 303         Queue_up,
 304 };
 305
 306 struct blk_queue_tag {
 307         struct request **tag_index;     /* map of busy tags */
 308         unsigned long *tag_map;         /* bit map of free/busy tags */
 309         struct list_head busy_list;     /* fifo list of busy tags */
 310         int busy;                       /* current depth */
 311         int max_depth;                  /* what we will send to device */
 312         int real_max_depth;             /* what the array can hold */
 313         atomic_t refcnt;                /* map can be shared */
 314 };
 315
 316 struct request_queue
 317 {
 318         /*
 319          * Together with queue_head for cacheline sharing
 320          */
 321         struct list_head        queue_head;
 322         struct request          *last_merge;
 323         elevator_t              *elevator;
 324
 325         /*
 326          * the queue request freelist, one for reads and one for writes
 327          */
 328         struct request_list     rq;
 329
 330         request_fn_proc         *request_fn;
 331         merge_request_fn        *back_merge_fn;
 332         merge_request_fn        *front_merge_fn;
 333         merge_requests_fn       *merge_requests_fn;
 334         make_request_fn         *make_request_fn;
 335         prep_rq_fn              *prep_rq_fn;
 336         unplug_fn               *unplug_fn;
 337         merge_bvec_fn           *merge_bvec_fn;
 338         activity_fn             *activity_fn;
 339         issue_flush_fn          *issue_flush_fn;
 340         prepare_flush_fn        *prepare_flush_fn;
 341         softirq_done_fn         *softirq_done_fn;
 342
 343         /*
 344          * Dispatch queue sorting
 345          */
 346         sector_t                end_sector;
 347         struct request          *boundary_rq;
 348
 349         /*
 350          * Auto-unplugging state
 351          */
 352         struct timer_list       unplug_timer;
 353         int                     unplug_thresh;  /* After this many requests */
 354         unsigned long           unplug_delay;   /* After this many jiffies */
 355         struct work_struct      unplug_work;
 356
 357         struct backing_dev_info backing_dev_info;
 358
 359         /*
 360          * The queue owner gets to use this for whatever they like.
 361          * ll_rw_blk doesn't touch it.
 362          */
 363         void                    *queuedata;
 364
 365         void                    *activity_data;
 366
 367         /*
 368          * queue needs bounce pages for pages above this limit
 369          */
 370         unsigned long           bounce_pfn;
 371         gfp_t                   bounce_gfp;
 372
 373         /*
 374          * various queue flags, see QUEUE_* below
 375          */
 376         unsigned long           queue_flags;
 377
 378         /*
 379          * protects queue structures from reentrancy. ->__queue_lock should
 380          * _never_ be used directly, it is queue private. always use
 381          * ->queue_lock.
 382          */
 383         spinlock_t              __queue_lock;
 384         spinlock_t              *queue_lock;
 385
 386         /*
 387          * queue kobject
 388          */
 389         struct kobject kobj;
 390
 391         /*
 392          * queue settings
 393          */
 394         unsigned long           nr_requests;    /* Max # of requests */
 395         unsigned int            nr_congestion_on;
 396         unsigned int            nr_congestion_off;
 397         unsigned int            nr_batching;
 398
 399         unsigned int            max_sectors;
 400         unsigned int            max_hw_sectors;
 401         unsigned short          max_phys_segments;
 402         unsigned short          max_hw_segments;
 403         unsigned short          hardsect_size;
 404         unsigned int            max_segment_size;
 405
 406         unsigned long           seg_boundary_mask;
 407         unsigned int            dma_alignment;
 408
 409         struct blk_queue_tag    *queue_tags;
 410
 411         unsigned int            nr_sorted;
 412         unsigned int            in_flight;
 413
 414         /*
 415          * sg stuff
 416          */
 417         unsigned int            sg_timeout;
 418         unsigned int            sg_reserved_size;
 419         int                     node;
 420
 421         struct blk_trace        *blk_trace;
 422
 423         /*
 424          * reserved for flush operations
 425          */
 426         unsigned int            ordered, next_ordered, ordseq;
 427         int                     orderr, ordcolor;
 428         struct request          pre_flush_rq, bar_rq, post_flush_rq;
 429         struct request          *orig_bar_rq;
 430         unsigned int            bi_size;
 431
 432         struct mutex            sysfs_lock;
 433 };
 434
 435 #define RQ_INACTIVE             (-1)
 436 #define RQ_ACTIVE               1
 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_ELVSWITCH    8       /* don't use elevator, just do FIFO */
 447
 448 enum {
 449         /*
 450          * Hardbarrier is supported with one of the following methods.
 451          *
 452          * NONE         : hardbarrier unsupported
 453          * DRAIN        : ordering by draining is enough
 454          * DRAIN_FLUSH  : ordering by draining w/ pre and post flushes
 455          * DRAIN_FUA    : ordering by draining w/ pre flush and FUA write
 456          * TAG          : ordering by tag is enough
 457          * TAG_FLUSH    : ordering by tag w/ pre and post flushes
 458          * TAG_FUA      : ordering by tag w/ pre flush and FUA write
 459          */
 460         QUEUE_ORDERED_NONE      = 0x00,
 461         QUEUE_ORDERED_DRAIN     = 0x01,
 462         QUEUE_ORDERED_TAG       = 0x02,
 463
 464         QUEUE_ORDERED_PREFLUSH  = 0x10,
 465         QUEUE_ORDERED_POSTFLUSH = 0x20,
 466         QUEUE_ORDERED_FUA       = 0x40,
 467
 468         QUEUE_ORDERED_DRAIN_FLUSH = QUEUE_ORDERED_DRAIN |
 469                         QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH,
 470         QUEUE_ORDERED_DRAIN_FUA = QUEUE_ORDERED_DRAIN |
 471                         QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_FUA,
 472         QUEUE_ORDERED_TAG_FLUSH = QUEUE_ORDERED_TAG |
 473                         QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH,
 474         QUEUE_ORDERED_TAG_FUA   = QUEUE_ORDERED_TAG |
 475                         QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_FUA,
 476
 477         /*
 478          * Ordered operation sequence
 479          */
 480         QUEUE_ORDSEQ_STARTED    = 0x01, /* flushing in progress */
 481         QUEUE_ORDSEQ_DRAIN      = 0x02, /* waiting for the queue to be drained */
 482         QUEUE_ORDSEQ_PREFLUSH   = 0x04, /* pre-flushing in progress */
 483         QUEUE_ORDSEQ_BAR        = 0x08, /* original barrier req in progress */
 484         QUEUE_ORDSEQ_POSTFLUSH  = 0x10, /* post-flushing in progress */
 485         QUEUE_ORDSEQ_DONE       = 0x20,
 486 };
 487
 488 #define blk_queue_plugged(q)    test_bit(QUEUE_FLAG_PLUGGED, &(q)->queue_flags)
 489 #define blk_queue_tagged(q)     test_bit(QUEUE_FLAG_QUEUED, &(q)->queue_flags)
 490 #define blk_queue_stopped(q)    test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
 491 #define blk_queue_flushing(q)   ((q)->ordseq)
 492
 493 #define blk_fs_request(rq)      ((rq)->flags & REQ_CMD)
 494 #define blk_pc_request(rq)      ((rq)->flags & REQ_BLOCK_PC)
 495 #define blk_noretry_request(rq) ((rq)->flags & REQ_FAILFAST)
 496 #define blk_rq_started(rq)      ((rq)->flags & REQ_STARTED)
 497
 498 #define blk_account_rq(rq)      (blk_rq_started(rq) && blk_fs_request(rq))
 499
 500 #define blk_pm_suspend_request(rq)      ((rq)->flags & REQ_PM_SUSPEND)
 501 #define blk_pm_resume_request(rq)       ((rq)->flags & REQ_PM_RESUME)
 502 #define blk_pm_request(rq)      \
 503         ((rq)->flags & (REQ_PM_SUSPEND | REQ_PM_RESUME))
 504
 505 #define blk_sorted_rq(rq)       ((rq)->flags & REQ_SORTED)
 506 #define blk_barrier_rq(rq)      ((rq)->flags & REQ_HARDBARRIER)
 507 #define blk_fua_rq(rq)          ((rq)->flags & REQ_FUA)
 508
 509 #define list_entry_rq(ptr)      list_entry((ptr), struct request, queuelist)
 510
 511 #define rq_data_dir(rq)         ((rq)->flags & 1)
 512
 513 static inline int blk_queue_full(struct request_queue *q, int rw)
 514 {
 515         if (rw == READ)
 516                 return test_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 517         return test_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 518 }
 519
 520 static inline void blk_set_queue_full(struct request_queue *q, int rw)
 521 {
 522         if (rw == READ)
 523                 set_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 524         else
 525                 set_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 526 }
 527
 528 static inline void blk_clear_queue_full(struct request_queue *q, int rw)
 529 {
 530         if (rw == READ)
 531                 clear_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 532         else
 533                 clear_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 534 }
 535
 536
 537 /*
 538  * mergeable request must not have _NOMERGE or _BARRIER bit set, nor may
 539  * it already be started by driver.
 540  */
 541 #define RQ_NOMERGE_FLAGS        \
 542         (REQ_NOMERGE | REQ_STARTED | REQ_HARDBARRIER | REQ_SOFTBARRIER)
 543 #define rq_mergeable(rq)        \
 544         (!((rq)->flags & RQ_NOMERGE_FLAGS) && blk_fs_request((rq)))
 545
 546 /*
 547  * noop, requests are automagically marked as active/inactive by I/O
 548  * scheduler -- see elv_next_request
 549  */
 550 #define blk_queue_headactive(q, head_active)
 551
 552 /*
 553  * q->prep_rq_fn return values
 554  */
 555 #define BLKPREP_OK              0       /* serve it */
 556 #define BLKPREP_KILL            1       /* fatal error, kill */
 557 #define BLKPREP_DEFER           2       /* leave on queue */
 558
 559 extern unsigned long blk_max_low_pfn, blk_max_pfn;
 560
 561 /*
 562  * standard bounce addresses:
 563  *
 564  * BLK_BOUNCE_HIGH      : bounce all highmem pages
 565  * BLK_BOUNCE_ANY       : don't bounce anything
 566  * BLK_BOUNCE_ISA       : bounce pages above ISA DMA boundary
 567  */
 568 #define BLK_BOUNCE_HIGH         ((u64)blk_max_low_pfn << PAGE_SHIFT)
 569 #define BLK_BOUNCE_ANY          ((u64)blk_max_pfn << PAGE_SHIFT)
 570 #define BLK_BOUNCE_ISA          (ISA_DMA_THRESHOLD)
 571
 572 #ifdef CONFIG_MMU
 573 extern int init_emergency_isa_pool(void);
 574 extern void blk_queue_bounce(request_queue_t *q, struct bio **bio);
 575 #else
 576 static inline int init_emergency_isa_pool(void)
 577 {
 578         return 0;
 579 }
 580 static inline void blk_queue_bounce(request_queue_t *q, struct bio **bio)
 581 {
 582 }
 583 #endif /* CONFIG_MMU */
 584
 585 #define rq_for_each_bio(_bio, rq)       \
 586         if ((rq->bio))                  \
 587                 for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)
 588
 589 struct sec_size {
 590         unsigned block_size;
 591         unsigned block_size_bits;
 592 };
 593
 594 extern int blk_register_queue(struct gendisk *disk);
 595 extern void blk_unregister_queue(struct gendisk *disk);
 596 extern void register_disk(struct gendisk *dev);
 597 extern void generic_make_request(struct bio *bio);
 598 extern void blk_put_request(struct request *);
 599 extern void __blk_put_request(request_queue_t *, struct request *);
 600 extern void blk_end_sync_rq(struct request *rq, int error);
 601 extern struct request *blk_get_request(request_queue_t *, int, gfp_t);
 602 extern void blk_insert_request(request_queue_t *, struct request *, int, void *);
 603 extern void blk_requeue_request(request_queue_t *, struct request *);
 604 extern void blk_plug_device(request_queue_t *);
 605 extern int blk_remove_plug(request_queue_t *);
 606 extern void blk_recount_segments(request_queue_t *, struct bio *);
 607 extern int scsi_cmd_ioctl(struct file *, struct gendisk *, unsigned int, void __user *);
 608 extern int sg_scsi_ioctl(struct file *, struct request_queue *,
 609                 struct gendisk *, struct scsi_ioctl_command __user *);
 610 extern void blk_start_queue(request_queue_t *q);
 611 extern void blk_stop_queue(request_queue_t *q);
 612 extern void blk_sync_queue(struct request_queue *q);
 613 extern void __blk_stop_queue(request_queue_t *q);
 614 extern void blk_run_queue(request_queue_t *);
 615 extern void blk_queue_activity_fn(request_queue_t *, activity_fn *, void *);
 616 extern int blk_rq_map_user(request_queue_t *, struct request *, void __user *, unsigned int);
 617 extern int blk_rq_unmap_user(struct bio *, unsigned int);
 618 extern int blk_rq_map_kern(request_queue_t *, struct request *, void *, unsigned int, gfp_t);
 619 extern int blk_rq_map_user_iov(request_queue_t *, struct request *, struct sg_iovec *, int);
 620 extern int blk_execute_rq(request_queue_t *, struct gendisk *,
 621                           struct request *, int);
 622 extern void blk_execute_rq_nowait(request_queue_t *, struct gendisk *,
 623                                   struct request *, int, rq_end_io_fn *);
 624
 625 static inline request_queue_t *bdev_get_queue(struct block_device *bdev)
 626 {
 627         return bdev->bd_disk->queue;
 628 }
 629
 630 static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
 631                                        struct page *page)
 632 {
 633         if (bdi && bdi->unplug_io_fn)
 634                 bdi->unplug_io_fn(bdi, page);
 635 }
 636
 637 static inline void blk_run_address_space(struct address_space *mapping)
 638 {
 639         if (mapping)
 640                 blk_run_backing_dev(mapping->backing_dev_info, NULL);
 641 }
 642
 643 /*
 644  * end_request() and friends. Must be called with the request queue spinlock
 645  * acquired. All functions called within end_request() _must_be_ atomic.
 646  *
 647  * Several drivers define their own end_request and call
 648  * end_that_request_first() and end_that_request_last()
 649  * for parts of the original function. This prevents
 650  * code duplication in drivers.
 651  */
 652 extern int end_that_request_first(struct request *, int, int);
 653 extern int end_that_request_chunk(struct request *, int, int);
 654 extern void end_that_request_last(struct request *, int);
 655 extern void end_request(struct request *req, int uptodate);
 656 extern void blk_complete_request(struct request *);
 657
 658 static inline int rq_all_done(struct request *rq, unsigned int nr_bytes)
 659 {
 660         if (blk_fs_request(rq))
 661                 return (nr_bytes >= (rq->hard_nr_sectors << 9));
 662         else if (blk_pc_request(rq))
 663                 return nr_bytes >= rq->data_len;
 664
 665         return 0;
 666 }
 667
 668 /*
 669  * end_that_request_first/chunk() takes an uptodate argument. we account
 670  * any value <= as an io error. 0 means -EIO for compatability reasons,
 671  * any other < 0 value is the direct error type. An uptodate value of
 672  * 1 indicates successful io completion
 673  */
 674 #define end_io_error(uptodate)  (unlikely((uptodate) <= 0))
 675
 676 static inline void blkdev_dequeue_request(struct request *req)
 677 {
 678         elv_dequeue_request(req->q, req);
 679 }
 680
 681 /*
 682  * This should be in elevator.h, but that requires pulling in rq and q
 683  */
 684 static inline void elv_dispatch_add_tail(struct request_queue *q,
 685                                          struct request *rq)
 686 {
 687         if (q->last_merge == rq)
 688                 q->last_merge = NULL;
 689         q->nr_sorted--;
 690
 691         q->end_sector = rq_end_sector(rq);
 692         q->boundary_rq = rq;
 693         list_add_tail(&rq->queuelist, &q->queue_head);
 694 }
 695
 696 /*
 697  * Access functions for manipulating queue properties
 698  */
 699 extern request_queue_t *blk_init_queue_node(request_fn_proc *rfn,
 700                                         spinlock_t *lock, int node_id);
 701 extern request_queue_t *blk_init_queue(request_fn_proc *, spinlock_t *);
 702 extern void blk_cleanup_queue(request_queue_t *);
 703 extern void blk_queue_make_request(request_queue_t *, make_request_fn *);
 704 extern void blk_queue_bounce_limit(request_queue_t *, u64);
 705 extern void blk_queue_max_sectors(request_queue_t *, unsigned int);
 706 extern void blk_queue_max_phys_segments(request_queue_t *, unsigned short);
 707 extern void blk_queue_max_hw_segments(request_queue_t *, unsigned short);
 708 extern void blk_queue_max_segment_size(request_queue_t *, unsigned int);
 709 extern void blk_queue_hardsect_size(request_queue_t *, unsigned short);
 710 extern void blk_queue_stack_limits(request_queue_t *t, request_queue_t *b);
 711 extern void blk_queue_segment_boundary(request_queue_t *, unsigned long);
 712 extern void blk_queue_prep_rq(request_queue_t *, prep_rq_fn *pfn);
 713 extern void blk_queue_merge_bvec(request_queue_t *, merge_bvec_fn *);
 714 extern void blk_queue_dma_alignment(request_queue_t *, int);
 715 extern void blk_queue_softirq_done(request_queue_t *, softirq_done_fn *);
 716 extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);
 717 extern int blk_queue_ordered(request_queue_t *, unsigned, prepare_flush_fn *);
 718 extern void blk_queue_issue_flush_fn(request_queue_t *, issue_flush_fn *);
 719 extern int blk_do_ordered(request_queue_t *, struct request **);
 720 extern unsigned blk_ordered_cur_seq(request_queue_t *);
 721 extern unsigned blk_ordered_req_seq(struct request *);
 722 extern void blk_ordered_complete_seq(request_queue_t *, unsigned, int);
 723
 724 extern int blk_rq_map_sg(request_queue_t *, struct request *, struct scatterlist *);
 725 extern void blk_dump_rq_flags(struct request *, char *);
 726 extern void generic_unplug_device(request_queue_t *);
 727 extern void __generic_unplug_device(request_queue_t *);
 728 extern long nr_blockdev_pages(void);
 729
 730 int blk_get_queue(request_queue_t *);
 731 request_queue_t *blk_alloc_queue(gfp_t);
 732 request_queue_t *blk_alloc_queue_node(gfp_t, int);
 733 extern void blk_put_queue(request_queue_t *);
 734
 735 /*
 736  * tag stuff
 737  */
 738 #define blk_queue_tag_depth(q)          ((q)->queue_tags->busy)
 739 #define blk_queue_tag_queue(q)          ((q)->queue_tags->busy < (q)->queue_tags->max_depth)
 740 #define blk_rq_tagged(rq)               ((rq)->flags & REQ_QUEUED)
 741 extern int blk_queue_start_tag(request_queue_t *, struct request *);
 742 extern struct request *blk_queue_find_tag(request_queue_t *, int);
 743 extern void blk_queue_end_tag(request_queue_t *, struct request *);
 744 extern int blk_queue_init_tags(request_queue_t *, int, struct blk_queue_tag *);
 745 extern void blk_queue_free_tags(request_queue_t *);
 746 extern int blk_queue_resize_tags(request_queue_t *, int);
 747 extern void blk_queue_invalidate_tags(request_queue_t *);
 748 extern long blk_congestion_wait(int rw, long timeout);
 749
 750 extern void blk_rq_bio_prep(request_queue_t *, struct request *, struct bio *);
 751 extern int blkdev_issue_flush(struct block_device *, sector_t *);
 752
 753 #define MAX_PHYS_SEGMENTS 128
 754 #define MAX_HW_SEGMENTS 128
 755 #define SAFE_MAX_SECTORS 255
 756 #define BLK_DEF_MAX_SECTORS 1024
 757
 758 #define MAX_SEGMENT_SIZE        65536
 759
 760 #define blkdev_entry_to_request(entry) list_entry((entry), struct request, queuelist)
 761
 762 static inline int queue_hardsect_size(request_queue_t *q)
 763 {
 764         int retval = 512;
 765
 766         if (q && q->hardsect_size)
 767                 retval = q->hardsect_size;
 768
 769         return retval;
 770 }
 771
 772 static inline int bdev_hardsect_size(struct block_device *bdev)
 773 {
 774         return queue_hardsect_size(bdev_get_queue(bdev));
 775 }
 776
 777 static inline int queue_dma_alignment(request_queue_t *q)
 778 {
 779         int retval = 511;
 780
 781         if (q && q->dma_alignment)
 782                 retval = q->dma_alignment;
 783
 784         return retval;
 785 }
 786
 787 static inline int bdev_dma_aligment(struct block_device *bdev)
 788 {
 789         return queue_dma_alignment(bdev_get_queue(bdev));
 790 }
 791
 792 #define blk_finished_io(nsects) do { } while (0)
 793 #define blk_started_io(nsects)  do { } while (0)
 794
 795 /* assumes size > 256 */
 796 static inline unsigned int blksize_bits(unsigned int size)
 797 {
 798         unsigned int bits = 8;
 799         do {
 800                 bits++;
 801                 size >>= 1;
 802         } while (size > 256);
 803         return bits;
 804 }
 805
 806 static inline unsigned int block_size(struct block_device *bdev)
 807 {
 808         return bdev->bd_block_size;
 809 }
 810
 811 typedef struct {struct page *v;} Sector;
 812
 813 unsigned char *read_dev_sector(struct block_device *, sector_t, Sector *);
 814
 815 static inline void put_dev_sector(Sector p)
 816 {
 817         page_cache_release(p.v);
 818 }
 819
 820 struct work_struct;
 821 int kblockd_schedule_work(struct work_struct *work);
 822 void kblockd_flush(void);
 823
 824 #ifdef CONFIG_LBD
 825 # include <asm/div64.h>
 826 # define sector_div(a, b) do_div(a, b)
 827 #else
 828 # define sector_div(n, b)( \
 829 { \
 830         int _res; \
 831         _res = (n) % (b); \
 832         (n) /= (b); \
 833         _res; \
 834 } \
 835 )
 836 #endif
 837
 838 #define MODULE_ALIAS_BLOCKDEV(major,minor) \
 839         MODULE_ALIAS("block-major-" __stringify(major) "-" __stringify(minor))
 840 #define MODULE_ALIAS_BLOCKDEV_MAJOR(major) \
 841         MODULE_ALIAS("block-major-" __stringify(major) "-*")
 842
 843
 844 #endif