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 struct blk_trace;
  26
  27 #define BLKDEV_MIN_RQ   4
  28 #define BLKDEV_MAX_RQ   128     /* Default maximum */
  29
  30 /*
  31  * This is the per-process anticipatory I/O scheduler state.
  32  */
  33 struct as_io_context {
  34         spinlock_t lock;
  35
  36         void (*dtor)(struct as_io_context *aic); /* destructor */
  37         void (*exit)(struct as_io_context *aic); /* called on task exit */
  38
  39         unsigned long state;
  40         atomic_t nr_queued; /* queued reads & sync writes */
  41         atomic_t nr_dispatched; /* number of requests gone to the drivers */
  42
  43         /* IO History tracking */
  44         /* Thinktime */
  45         unsigned long last_end_request;
  46         unsigned long ttime_total;
  47         unsigned long ttime_samples;
  48         unsigned long ttime_mean;
  49         /* Layout pattern */
  50         unsigned int seek_samples;
  51         sector_t last_request_pos;
  52         u64 seek_total;
  53         sector_t seek_mean;
  54 };
  55
  56 struct cfq_queue;
  57 struct cfq_io_context {
  58         struct rb_node rb_node;
  59         void *key;
  60
  61         struct cfq_queue *cfqq[2];
  62
  63         struct io_context *ioc;
  64
  65         unsigned long last_end_request;
  66         sector_t last_request_pos;
  67         unsigned long last_queue;
  68
  69         unsigned long ttime_total;
  70         unsigned long ttime_samples;
  71         unsigned long ttime_mean;
  72
  73         unsigned int seek_samples;
  74         u64 seek_total;
  75         sector_t seek_mean;
  76
  77         struct list_head queue_list;
  78
  79         void (*dtor)(struct io_context *); /* destructor */
  80         void (*exit)(struct io_context *); /* called on task exit */
  81 };
  82
  83 /*
  84  * This is the per-process I/O subsystem state.  It is refcounted and
  85  * kmalloc'ed. Currently all fields are modified in process io context
  86  * (apart from the atomic refcount), so require no locking.
  87  */
  88 struct io_context {
  89         atomic_t refcount;
  90         struct task_struct *task;
  91
  92         int (*set_ioprio)(struct io_context *, unsigned int);
  93
  94         /*
  95          * For request batching
  96          */
  97         unsigned long last_waited; /* Time last woken after wait for request */
  98         int nr_batch_requests;     /* Number of requests left in the batch */
  99
 100         struct as_io_context *aic;
 101         struct rb_root cic_root;
 102 };
 103
 104 void put_io_context(struct io_context *ioc);
 105 void exit_io_context(void);
 106 struct io_context *current_io_context(gfp_t gfp_flags);
 107 struct io_context *get_io_context(gfp_t gfp_flags);
 108 void copy_io_context(struct io_context **pdst, struct io_context **psrc);
 109 void swap_io_context(struct io_context **ioc1, struct io_context **ioc2);
 110
 111 struct request;
 112 typedef void (rq_end_io_fn)(struct request *, int);
 113
 114 struct request_list {
 115         int count[2];
 116         int starved[2];
 117         int elvpriv;
 118         mempool_t *rq_pool;
 119         wait_queue_head_t wait[2];
 120 };
 121
 122 #define BLK_MAX_CDB     16
 123
 124 /*
 125  * try to put the fields that are referenced together in the same cacheline
 126  */
 127 struct request {
 128         struct list_head queuelist;
 129         struct list_head donelist;
 130
 131         unsigned long flags;            /* see REQ_ bits below */
 132
 133         /* Maintain bio traversal state for part by part I/O submission.
 134          * hard_* are block layer internals, no driver should touch them!
 135          */
 136
 137         sector_t sector;                /* next sector to submit */
 138         unsigned long nr_sectors;       /* no. of sectors left to submit */
 139         /* no. of sectors left to submit in the current segment */
 140         unsigned int current_nr_sectors;
 141
 142         sector_t hard_sector;           /* next sector to complete */
 143         unsigned long hard_nr_sectors;  /* no. of sectors left to complete */
 144         /* no. of sectors left to complete in the current segment */
 145         unsigned int hard_cur_sectors;
 146
 147         struct bio *bio;
 148         struct bio *biotail;
 149
 150         void *elevator_private;
 151         void *completion_data;
 152
 153         unsigned short ioprio;
 154
 155         int rq_status;  /* should split this into a few status bits */
 156         struct gendisk *rq_disk;
 157         int errors;
 158         unsigned long start_time;
 159
 160         /* Number of scatter-gather DMA addr+len pairs after
 161          * physical address coalescing is performed.
 162          */
 163         unsigned short nr_phys_segments;
 164
 165         /* Number of scatter-gather addr+len pairs after
 166          * physical and DMA remapping hardware coalescing is performed.
 167          * This is the number of scatter-gather entries the driver
 168          * will actually have to deal with after DMA mapping is done.
 169          */
 170         unsigned short nr_hw_segments;
 171
 172         int tag;
 173         char *buffer;
 174
 175         int ref_count;
 176         request_queue_t *q;
 177         struct request_list *rl;
 178
 179         struct completion *waiting;
 180         void *special;
 181
 182         /*
 183          * when request is used as a packet command carrier
 184          */
 185         unsigned int cmd_len;
 186         unsigned char cmd[BLK_MAX_CDB];
 187
 188         unsigned int data_len;
 189         void *data;
 190
 191         unsigned int sense_len;
 192         void *sense;
 193
 194         unsigned int timeout;
 195         int retries;
 196
 197         /*
 198          * For Power Management requests
 199          */
 200         struct request_pm_state *pm;
 201
 202         /*
 203          * completion callback. end_io_data should be folded in with waiting
 204          */
 205         rq_end_io_fn *end_io;
 206         void *end_io_data;
 207 };
 208
 209 /*
 210  * first three bits match BIO_RW* bits, important
 211  */
 212 enum rq_flag_bits {
 213         __REQ_RW,               /* not set, read. set, write */
 214         __REQ_FAILFAST,         /* no low level driver retries */
 215         __REQ_SORTED,           /* elevator knows about this request */
 216         __REQ_SOFTBARRIER,      /* may not be passed by ioscheduler */
 217         __REQ_HARDBARRIER,      /* may not be passed by drive either */
 218         __REQ_FUA,              /* forced unit access */
 219         __REQ_CMD,              /* is a regular fs rw request */
 220         __REQ_NOMERGE,          /* don't touch this for merging */
 221         __REQ_STARTED,          /* drive already may have started this one */
 222         __REQ_DONTPREP,         /* don't call prep for this one */
 223         __REQ_QUEUED,           /* uses queueing */
 224         __REQ_ELVPRIV,          /* elevator private data attached */
 225         /*
 226          * for ATA/ATAPI devices
 227          */
 228         __REQ_PC,               /* packet command (special) */
 229         __REQ_BLOCK_PC,         /* queued down pc from block layer */
 230         __REQ_SENSE,            /* sense retrival */
 231
 232         __REQ_FAILED,           /* set if the request failed */
 233         __REQ_QUIET,            /* don't worry about errors */
 234         __REQ_SPECIAL,          /* driver suplied command */
 235         __REQ_DRIVE_CMD,
 236         __REQ_DRIVE_TASK,
 237         __REQ_DRIVE_TASKFILE,
 238         __REQ_PREEMPT,          /* set for "ide_preempt" requests */
 239         __REQ_PM_SUSPEND,       /* suspend request */
 240         __REQ_PM_RESUME,        /* resume request */
 241         __REQ_PM_SHUTDOWN,      /* shutdown request */
 242         __REQ_ORDERED_COLOR,    /* is before or after barrier */
 243         __REQ_NR_BITS,          /* stops here */
 244 };
 245
 246 #define REQ_RW          (1 << __REQ_RW)
 247 #define REQ_FAILFAST    (1 << __REQ_FAILFAST)
 248 #define REQ_SORTED      (1 << __REQ_SORTED)
 249 #define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER)
 250 #define REQ_HARDBARRIER (1 << __REQ_HARDBARRIER)
 251 #define REQ_FUA         (1 << __REQ_FUA)
 252 #define REQ_CMD         (1 << __REQ_CMD)
 253 #define REQ_NOMERGE     (1 << __REQ_NOMERGE)
 254 #define REQ_STARTED     (1 << __REQ_STARTED)
 255 #define REQ_DONTPREP    (1 << __REQ_DONTPREP)
 256 #define REQ_QUEUED      (1 << __REQ_QUEUED)
 257 #define REQ_ELVPRIV     (1 << __REQ_ELVPRIV)
 258 #define REQ_PC          (1 << __REQ_PC)
 259 #define REQ_BLOCK_PC    (1 << __REQ_BLOCK_PC)
 260 #define REQ_SENSE       (1 << __REQ_SENSE)
 261 #define REQ_FAILED      (1 << __REQ_FAILED)
 262 #define REQ_QUIET       (1 << __REQ_QUIET)
 263 #define REQ_SPECIAL     (1 << __REQ_SPECIAL)
 264 #define REQ_DRIVE_CMD   (1 << __REQ_DRIVE_CMD)
 265 #define REQ_DRIVE_TASK  (1 << __REQ_DRIVE_TASK)
 266 #define REQ_DRIVE_TASKFILE      (1 << __REQ_DRIVE_TASKFILE)
 267 #define REQ_PREEMPT     (1 << __REQ_PREEMPT)
 268 #define REQ_PM_SUSPEND  (1 << __REQ_PM_SUSPEND)
 269 #define REQ_PM_RESUME   (1 << __REQ_PM_RESUME)
 270 #define REQ_PM_SHUTDOWN (1 << __REQ_PM_SHUTDOWN)
 271 #define REQ_ORDERED_COLOR       (1 << __REQ_ORDERED_COLOR)
 272
 273 /*
 274  * State information carried for REQ_PM_SUSPEND and REQ_PM_RESUME
 275  * requests. Some step values could eventually be made generic.
 276  */
 277 struct request_pm_state
 278 {
 279         /* PM state machine step value, currently driver specific */
 280         int     pm_step;
 281         /* requested PM state value (S1, S2, S3, S4, ...) */
 282         u32     pm_state;
 283         void*   data;           /* for driver use */
 284 };
 285
 286 #include <linux/elevator.h>
 287
 288 typedef int (merge_request_fn) (request_queue_t *, struct request *,
 289                                 struct bio *);
 290 typedef int (merge_requests_fn) (request_queue_t *, struct request *,
 291                                  struct request *);
 292 typedef void (request_fn_proc) (request_queue_t *q);
 293 typedef int (make_request_fn) (request_queue_t *q, struct bio *bio);
 294 typedef int (prep_rq_fn) (request_queue_t *, struct request *);
 295 typedef void (unplug_fn) (request_queue_t *);
 296
 297 struct bio_vec;
 298 typedef int (merge_bvec_fn) (request_queue_t *, struct bio *, struct bio_vec *);
 299 typedef void (activity_fn) (void *data, int rw);
 300 typedef int (issue_flush_fn) (request_queue_t *, struct gendisk *, sector_t *);
 301 typedef void (prepare_flush_fn) (request_queue_t *, struct request *);
 302 typedef void (softirq_done_fn)(struct request *);
 303
 304 enum blk_queue_state {
 305         Queue_down,
 306         Queue_up,
 307 };
 308
 309 struct blk_queue_tag {
 310         struct request **tag_index;     /* map of busy tags */
 311         unsigned long *tag_map;         /* bit map of free/busy tags */
 312         struct list_head busy_list;     /* fifo list of busy tags */
 313         int busy;                       /* current depth */
 314         int max_depth;                  /* what we will send to device */
 315         int real_max_depth;             /* what the array can hold */
 316         atomic_t refcnt;                /* map can be shared */
 317 };
 318
 319 struct request_queue
 320 {
 321         /*
 322          * Together with queue_head for cacheline sharing
 323          */
 324         struct list_head        queue_head;
 325         struct request          *last_merge;
 326         elevator_t              *elevator;
 327
 328         /*
 329          * the queue request freelist, one for reads and one for writes
 330          */
 331         struct request_list     rq;
 332
 333         request_fn_proc         *request_fn;
 334         merge_request_fn        *back_merge_fn;
 335         merge_request_fn        *front_merge_fn;
 336         merge_requests_fn       *merge_requests_fn;
 337         make_request_fn         *make_request_fn;
 338         prep_rq_fn              *prep_rq_fn;
 339         unplug_fn               *unplug_fn;
 340         merge_bvec_fn           *merge_bvec_fn;
 341         activity_fn             *activity_fn;
 342         issue_flush_fn          *issue_flush_fn;
 343         prepare_flush_fn        *prepare_flush_fn;
 344         softirq_done_fn         *softirq_done_fn;
 345
 346         /*
 347          * Dispatch queue sorting
 348          */
 349         sector_t                end_sector;
 350         struct request          *boundary_rq;
 351
 352         /*
 353          * Auto-unplugging state
 354          */
 355         struct timer_list       unplug_timer;
 356         int                     unplug_thresh;  /* After this many requests */
 357         unsigned long           unplug_delay;   /* After this many jiffies */
 358         struct work_struct      unplug_work;
 359
 360         struct backing_dev_info backing_dev_info;
 361
 362         /*
 363          * The queue owner gets to use this for whatever they like.
 364          * ll_rw_blk doesn't touch it.
 365          */
 366         void                    *queuedata;
 367
 368         void                    *activity_data;
 369
 370         /*
 371          * queue needs bounce pages for pages above this limit
 372          */
 373         unsigned long           bounce_pfn;
 374         gfp_t                   bounce_gfp;
 375
 376         /*
 377          * various queue flags, see QUEUE_* below
 378          */
 379         unsigned long           queue_flags;
 380
 381         /*
 382          * protects queue structures from reentrancy. ->__queue_lock should
 383          * _never_ be used directly, it is queue private. always use
 384          * ->queue_lock.
 385          */
 386         spinlock_t              __queue_lock;
 387         spinlock_t              *queue_lock;
 388
 389         /*
 390          * queue kobject
 391          */
 392         struct kobject kobj;
 393
 394         /*
 395          * queue settings
 396          */
 397         unsigned long           nr_requests;    /* Max # of requests */
 398         unsigned int            nr_congestion_on;
 399         unsigned int            nr_congestion_off;
 400         unsigned int            nr_batching;
 401
 402         unsigned int            max_sectors;
 403         unsigned int            max_hw_sectors;
 404         unsigned short          max_phys_segments;
 405         unsigned short          max_hw_segments;
 406         unsigned short          hardsect_size;
 407         unsigned int            max_segment_size;
 408
 409         unsigned long           seg_boundary_mask;
 410         unsigned int            dma_alignment;
 411
 412         struct blk_queue_tag    *queue_tags;
 413
 414         unsigned int            nr_sorted;
 415         unsigned int            in_flight;
 416
 417         /*
 418          * sg stuff
 419          */
 420         unsigned int            sg_timeout;
 421         unsigned int            sg_reserved_size;
 422         int                     node;
 423
 424         struct blk_trace        *blk_trace;
 425
 426         /*
 427          * reserved for flush operations
 428          */
 429         unsigned int            ordered, next_ordered, ordseq;
 430         int                     orderr, ordcolor;
 431         struct request          pre_flush_rq, bar_rq, post_flush_rq;
 432         struct request          *orig_bar_rq;
 433         unsigned int            bi_size;
 434
 435         struct mutex            sysfs_lock;
 436 };
 437
 438 #define RQ_INACTIVE             (-1)
 439 #define RQ_ACTIVE               1
 440 #define RQ_SCSI_BUSY            0xffff
 441 #define RQ_SCSI_DONE            0xfffe
 442 #define RQ_SCSI_DISCONNECTING   0xffe0
 443
 444 #define QUEUE_FLAG_CLUSTER      0       /* cluster several segments into 1 */
 445 #define QUEUE_FLAG_QUEUED       1       /* uses generic tag queueing */
 446 #define QUEUE_FLAG_STOPPED      2       /* queue is stopped */
 447 #define QUEUE_FLAG_READFULL     3       /* write queue has been filled */
 448 #define QUEUE_FLAG_WRITEFULL    4       /* read queue has been filled */
 449 #define QUEUE_FLAG_DEAD         5       /* queue being torn down */
 450 #define QUEUE_FLAG_REENTER      6       /* Re-entrancy avoidance */
 451 #define QUEUE_FLAG_PLUGGED      7       /* queue is plugged */
 452 #define QUEUE_FLAG_ELVSWITCH    8       /* don't use elevator, just do FIFO */
 453
 454 enum {
 455         /*
 456          * Hardbarrier is supported with one of the following methods.
 457          *
 458          * NONE         : hardbarrier unsupported
 459          * DRAIN        : ordering by draining is enough
 460          * DRAIN_FLUSH  : ordering by draining w/ pre and post flushes
 461          * DRAIN_FUA    : ordering by draining w/ pre flush and FUA write
 462          * TAG          : ordering by tag is enough
 463          * TAG_FLUSH    : ordering by tag w/ pre and post flushes
 464          * TAG_FUA      : ordering by tag w/ pre flush and FUA write
 465          */
 466         QUEUE_ORDERED_NONE      = 0x00,
 467         QUEUE_ORDERED_DRAIN     = 0x01,
 468         QUEUE_ORDERED_TAG       = 0x02,
 469
 470         QUEUE_ORDERED_PREFLUSH  = 0x10,
 471         QUEUE_ORDERED_POSTFLUSH = 0x20,
 472         QUEUE_ORDERED_FUA       = 0x40,
 473
 474         QUEUE_ORDERED_DRAIN_FLUSH = QUEUE_ORDERED_DRAIN |
 475                         QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH,
 476         QUEUE_ORDERED_DRAIN_FUA = QUEUE_ORDERED_DRAIN |
 477                         QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_FUA,
 478         QUEUE_ORDERED_TAG_FLUSH = QUEUE_ORDERED_TAG |
 479                         QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH,
 480         QUEUE_ORDERED_TAG_FUA   = QUEUE_ORDERED_TAG |
 481                         QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_FUA,
 482
 483         /*
 484          * Ordered operation sequence
 485          */
 486         QUEUE_ORDSEQ_STARTED    = 0x01, /* flushing in progress */
 487         QUEUE_ORDSEQ_DRAIN      = 0x02, /* waiting for the queue to be drained */
 488         QUEUE_ORDSEQ_PREFLUSH   = 0x04, /* pre-flushing in progress */
 489         QUEUE_ORDSEQ_BAR        = 0x08, /* original barrier req in progress */
 490         QUEUE_ORDSEQ_POSTFLUSH  = 0x10, /* post-flushing in progress */
 491         QUEUE_ORDSEQ_DONE       = 0x20,
 492 };
 493
 494 #define blk_queue_plugged(q)    test_bit(QUEUE_FLAG_PLUGGED, &(q)->queue_flags)
 495 #define blk_queue_tagged(q)     test_bit(QUEUE_FLAG_QUEUED, &(q)->queue_flags)
 496 #define blk_queue_stopped(q)    test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
 497 #define blk_queue_flushing(q)   ((q)->ordseq)
 498
 499 #define blk_fs_request(rq)      ((rq)->flags & REQ_CMD)
 500 #define blk_pc_request(rq)      ((rq)->flags & REQ_BLOCK_PC)
 501 #define blk_noretry_request(rq) ((rq)->flags & REQ_FAILFAST)
 502 #define blk_rq_started(rq)      ((rq)->flags & REQ_STARTED)
 503
 504 #define blk_account_rq(rq)      (blk_rq_started(rq) && blk_fs_request(rq))
 505
 506 #define blk_pm_suspend_request(rq)      ((rq)->flags & REQ_PM_SUSPEND)
 507 #define blk_pm_resume_request(rq)       ((rq)->flags & REQ_PM_RESUME)
 508 #define blk_pm_request(rq)      \
 509         ((rq)->flags & (REQ_PM_SUSPEND | REQ_PM_RESUME))
 510
 511 #define blk_sorted_rq(rq)       ((rq)->flags & REQ_SORTED)
 512 #define blk_barrier_rq(rq)      ((rq)->flags & REQ_HARDBARRIER)
 513 #define blk_fua_rq(rq)          ((rq)->flags & REQ_FUA)
 514
 515 #define list_entry_rq(ptr)      list_entry((ptr), struct request, queuelist)
 516
 517 #define rq_data_dir(rq)         ((rq)->flags & 1)
 518
 519 static inline int blk_queue_full(struct request_queue *q, int rw)
 520 {
 521         if (rw == READ)
 522                 return test_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 523         return test_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 524 }
 525
 526 static inline void blk_set_queue_full(struct request_queue *q, int rw)
 527 {
 528         if (rw == READ)
 529                 set_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 530         else
 531                 set_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 532 }
 533
 534 static inline void blk_clear_queue_full(struct request_queue *q, int rw)
 535 {
 536         if (rw == READ)
 537                 clear_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 538         else
 539                 clear_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 540 }
 541
 542
 543 /*
 544  * mergeable request must not have _NOMERGE or _BARRIER bit set, nor may
 545  * it already be started by driver.
 546  */
 547 #define RQ_NOMERGE_FLAGS        \
 548         (REQ_NOMERGE | REQ_STARTED | REQ_HARDBARRIER | REQ_SOFTBARRIER)
 549 #define rq_mergeable(rq)        \
 550         (!((rq)->flags & RQ_NOMERGE_FLAGS) && blk_fs_request((rq)))
 551
 552 /*
 553  * noop, requests are automagically marked as active/inactive by I/O
 554  * scheduler -- see elv_next_request
 555  */
 556 #define blk_queue_headactive(q, head_active)
 557
 558 /*
 559  * q->prep_rq_fn return values
 560  */
 561 #define BLKPREP_OK              0       /* serve it */
 562 #define BLKPREP_KILL            1       /* fatal error, kill */
 563 #define BLKPREP_DEFER           2       /* leave on queue */
 564
 565 extern unsigned long blk_max_low_pfn, blk_max_pfn;
 566
 567 /*
 568  * standard bounce addresses:
 569  *
 570  * BLK_BOUNCE_HIGH      : bounce all highmem pages
 571  * BLK_BOUNCE_ANY       : don't bounce anything
 572  * BLK_BOUNCE_ISA       : bounce pages above ISA DMA boundary
 573  */
 574 #define BLK_BOUNCE_HIGH         ((u64)blk_max_low_pfn << PAGE_SHIFT)
 575 #define BLK_BOUNCE_ANY          ((u64)blk_max_pfn << PAGE_SHIFT)
 576 #define BLK_BOUNCE_ISA          (ISA_DMA_THRESHOLD)
 577
 578 #ifdef CONFIG_MMU
 579 extern int init_emergency_isa_pool(void);
 580 extern void blk_queue_bounce(request_queue_t *q, struct bio **bio);
 581 #else
 582 static inline int init_emergency_isa_pool(void)
 583 {
 584         return 0;
 585 }
 586 static inline void blk_queue_bounce(request_queue_t *q, struct bio **bio)
 587 {
 588 }
 589 #endif /* CONFIG_MMU */
 590
 591 #define rq_for_each_bio(_bio, rq)       \
 592         if ((rq->bio))                  \
 593                 for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)
 594
 595 struct sec_size {
 596         unsigned block_size;
 597         unsigned block_size_bits;
 598 };
 599
 600 extern int blk_register_queue(struct gendisk *disk);
 601 extern void blk_unregister_queue(struct gendisk *disk);
 602 extern void register_disk(struct gendisk *dev);
 603 extern void generic_make_request(struct bio *bio);
 604 extern void blk_put_request(struct request *);
 605 extern void __blk_put_request(request_queue_t *, struct request *);
 606 extern void blk_end_sync_rq(struct request *rq, int error);
 607 extern struct request *blk_get_request(request_queue_t *, int, gfp_t);
 608 extern void blk_insert_request(request_queue_t *, struct request *, int, void *);
 609 extern void blk_requeue_request(request_queue_t *, struct request *);
 610 extern void blk_plug_device(request_queue_t *);
 611 extern int blk_remove_plug(request_queue_t *);
 612 extern void blk_recount_segments(request_queue_t *, struct bio *);
 613 extern int scsi_cmd_ioctl(struct file *, struct gendisk *, unsigned int, void __user *);
 614 extern void blk_start_queue(request_queue_t *q);
 615 extern void blk_stop_queue(request_queue_t *q);
 616 extern void blk_sync_queue(struct request_queue *q);
 617 extern void __blk_stop_queue(request_queue_t *q);
 618 extern void blk_run_queue(request_queue_t *);
 619 extern void blk_queue_activity_fn(request_queue_t *, activity_fn *, void *);
 620 extern int blk_rq_map_user(request_queue_t *, struct request *, void __user *, unsigned int);
 621 extern int blk_rq_unmap_user(struct bio *, unsigned int);
 622 extern int blk_rq_map_kern(request_queue_t *, struct request *, void *, unsigned int, gfp_t);
 623 extern int blk_rq_map_user_iov(request_queue_t *, struct request *, struct sg_iovec *, int);
 624 extern int blk_execute_rq(request_queue_t *, struct gendisk *,
 625                           struct request *, int);
 626 extern void blk_execute_rq_nowait(request_queue_t *, struct gendisk *,
 627                                   struct request *, int, rq_end_io_fn *);
 628
 629 static inline request_queue_t *bdev_get_queue(struct block_device *bdev)
 630 {
 631         return bdev->bd_disk->queue;
 632 }
 633
 634 static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
 635                                        struct page *page)
 636 {
 637         if (bdi && bdi->unplug_io_fn)
 638                 bdi->unplug_io_fn(bdi, page);
 639 }
 640
 641 static inline void blk_run_address_space(struct address_space *mapping)
 642 {
 643         if (mapping)
 644                 blk_run_backing_dev(mapping->backing_dev_info, NULL);
 645 }
 646
 647 /*
 648  * end_request() and friends. Must be called with the request queue spinlock
 649  * acquired. All functions called within end_request() _must_be_ atomic.
 650  *
 651  * Several drivers define their own end_request and call
 652  * end_that_request_first() and end_that_request_last()
 653  * for parts of the original function. This prevents
 654  * code duplication in drivers.
 655  */
 656 extern int end_that_request_first(struct request *, int, int);
 657 extern int end_that_request_chunk(struct request *, int, int);
 658 extern void end_that_request_last(struct request *, int);
 659 extern void end_request(struct request *req, int uptodate);
 660 extern void blk_complete_request(struct request *);
 661
 662 static inline int rq_all_done(struct request *rq, unsigned int nr_bytes)
 663 {
 664         if (blk_fs_request(rq))
 665                 return (nr_bytes >= (rq->hard_nr_sectors << 9));
 666         else if (blk_pc_request(rq))
 667                 return nr_bytes >= rq->data_len;
 668
 669         return 0;
 670 }
 671
 672 /*
 673  * end_that_request_first/chunk() takes an uptodate argument. we account
 674  * any value <= as an io error. 0 means -EIO for compatability reasons,
 675  * any other < 0 value is the direct error type. An uptodate value of
 676  * 1 indicates successful io completion
 677  */
 678 #define end_io_error(uptodate)  (unlikely((uptodate) <= 0))
 679
 680 static inline void blkdev_dequeue_request(struct request *req)
 681 {
 682         elv_dequeue_request(req->q, req);
 683 }
 684
 685 /*
 686  * This should be in elevator.h, but that requires pulling in rq and q
 687  */
 688 static inline void elv_dispatch_add_tail(struct request_queue *q,
 689                                          struct request *rq)
 690 {
 691         if (q->last_merge == rq)
 692                 q->last_merge = NULL;
 693         q->nr_sorted--;
 694
 695         q->end_sector = rq_end_sector(rq);
 696         q->boundary_rq = rq;
 697         list_add_tail(&rq->queuelist, &q->queue_head);
 698 }
 699
 700 /*
 701  * Access functions for manipulating queue properties
 702  */
 703 extern request_queue_t *blk_init_queue_node(request_fn_proc *rfn,
 704                                         spinlock_t *lock, int node_id);
 705 extern request_queue_t *blk_init_queue(request_fn_proc *, spinlock_t *);
 706 extern void blk_cleanup_queue(request_queue_t *);
 707 extern void blk_queue_make_request(request_queue_t *, make_request_fn *);
 708 extern void blk_queue_bounce_limit(request_queue_t *, u64);
 709 extern void blk_queue_max_sectors(request_queue_t *, unsigned int);
 710 extern void blk_queue_max_phys_segments(request_queue_t *, unsigned short);
 711 extern void blk_queue_max_hw_segments(request_queue_t *, unsigned short);
 712 extern void blk_queue_max_segment_size(request_queue_t *, unsigned int);
 713 extern void blk_queue_hardsect_size(request_queue_t *, unsigned short);
 714 extern void blk_queue_stack_limits(request_queue_t *t, request_queue_t *b);
 715 extern void blk_queue_segment_boundary(request_queue_t *, unsigned long);
 716 extern void blk_queue_prep_rq(request_queue_t *, prep_rq_fn *pfn);
 717 extern void blk_queue_merge_bvec(request_queue_t *, merge_bvec_fn *);
 718 extern void blk_queue_dma_alignment(request_queue_t *, int);
 719 extern void blk_queue_softirq_done(request_queue_t *, softirq_done_fn *);
 720 extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);
 721 extern int blk_queue_ordered(request_queue_t *, unsigned, prepare_flush_fn *);
 722 extern void blk_queue_issue_flush_fn(request_queue_t *, issue_flush_fn *);
 723 extern int blk_do_ordered(request_queue_t *, struct request **);
 724 extern unsigned blk_ordered_cur_seq(request_queue_t *);
 725 extern unsigned blk_ordered_req_seq(struct request *);
 726 extern void blk_ordered_complete_seq(request_queue_t *, unsigned, int);
 727
 728 extern int blk_rq_map_sg(request_queue_t *, struct request *, struct scatterlist *);
 729 extern void blk_dump_rq_flags(struct request *, char *);
 730 extern void generic_unplug_device(request_queue_t *);
 731 extern void __generic_unplug_device(request_queue_t *);
 732 extern long nr_blockdev_pages(void);
 733
 734 int blk_get_queue(request_queue_t *);
 735 request_queue_t *blk_alloc_queue(gfp_t);
 736 request_queue_t *blk_alloc_queue_node(gfp_t, int);
 737 extern void blk_put_queue(request_queue_t *);
 738
 739 /*
 740  * tag stuff
 741  */
 742 #define blk_queue_tag_depth(q)          ((q)->queue_tags->busy)
 743 #define blk_queue_tag_queue(q)          ((q)->queue_tags->busy < (q)->queue_tags->max_depth)
 744 #define blk_rq_tagged(rq)               ((rq)->flags & REQ_QUEUED)
 745 extern int blk_queue_start_tag(request_queue_t *, struct request *);
 746 extern struct request *blk_queue_find_tag(request_queue_t *, int);
 747 extern void blk_queue_end_tag(request_queue_t *, struct request *);
 748 extern int blk_queue_init_tags(request_queue_t *, int, struct blk_queue_tag *);
 749 extern void blk_queue_free_tags(request_queue_t *);
 750 extern int blk_queue_resize_tags(request_queue_t *, int);
 751 extern void blk_queue_invalidate_tags(request_queue_t *);
 752 extern long blk_congestion_wait(int rw, long timeout);
 753
 754 extern void blk_rq_bio_prep(request_queue_t *, struct request *, struct bio *);
 755 extern int blkdev_issue_flush(struct block_device *, sector_t *);
 756
 757 #define MAX_PHYS_SEGMENTS 128
 758 #define MAX_HW_SEGMENTS 128
 759 #define SAFE_MAX_SECTORS 255
 760 #define BLK_DEF_MAX_SECTORS 1024
 761
 762 #define MAX_SEGMENT_SIZE        65536
 763
 764 #define blkdev_entry_to_request(entry) list_entry((entry), struct request, queuelist)
 765
 766 static inline int queue_hardsect_size(request_queue_t *q)
 767 {
 768         int retval = 512;
 769
 770         if (q && q->hardsect_size)
 771                 retval = q->hardsect_size;
 772
 773         return retval;
 774 }
 775
 776 static inline int bdev_hardsect_size(struct block_device *bdev)
 777 {
 778         return queue_hardsect_size(bdev_get_queue(bdev));
 779 }
 780
 781 static inline int queue_dma_alignment(request_queue_t *q)
 782 {
 783         int retval = 511;
 784
 785         if (q && q->dma_alignment)
 786                 retval = q->dma_alignment;
 787
 788         return retval;
 789 }
 790
 791 static inline int bdev_dma_aligment(struct block_device *bdev)
 792 {
 793         return queue_dma_alignment(bdev_get_queue(bdev));
 794 }
 795
 796 #define blk_finished_io(nsects) do { } while (0)
 797 #define blk_started_io(nsects)  do { } while (0)
 798
 799 /* assumes size > 256 */
 800 static inline unsigned int blksize_bits(unsigned int size)
 801 {
 802         unsigned int bits = 8;
 803         do {
 804                 bits++;
 805                 size >>= 1;
 806         } while (size > 256);
 807         return bits;
 808 }
 809
 810 static inline unsigned int block_size(struct block_device *bdev)
 811 {
 812         return bdev->bd_block_size;
 813 }
 814
 815 typedef struct {struct page *v;} Sector;
 816
 817 unsigned char *read_dev_sector(struct block_device *, sector_t, Sector *);
 818
 819 static inline void put_dev_sector(Sector p)
 820 {
 821         page_cache_release(p.v);
 822 }
 823
 824 struct work_struct;
 825 int kblockd_schedule_work(struct work_struct *work);
 826 void kblockd_flush(void);
 827
 828 #ifdef CONFIG_LBD
 829 # include <asm/div64.h>
 830 # define sector_div(a, b) do_div(a, b)
 831 #else
 832 # define sector_div(n, b)( \
 833 { \
 834         int _res; \
 835         _res = (n) % (b); \
 836         (n) /= (b); \
 837         _res; \
 838 } \
 839 )
 840 #endif
 841
 842 #define MODULE_ALIAS_BLOCKDEV(major,minor) \
 843         MODULE_ALIAS("block-major-" __stringify(major) "-" __stringify(minor))
 844 #define MODULE_ALIAS_BLOCKDEV_MAJOR(major) \
 845         MODULE_ALIAS("block-major-" __stringify(major) "-*")
 846
 847
 848 #endif