include/linux/blkdev.h

   1 #ifndef _LINUX_BLKDEV_H
   2 #define _LINUX_BLKDEV_H
   3
   4 #ifdef CONFIG_BLOCK
   5
   6 #include <linux/sched.h>
   7 #include <linux/major.h>
   8 #include <linux/genhd.h>
   9 #include <linux/list.h>
  10 #include <linux/timer.h>
  11 #include <linux/workqueue.h>
  12 #include <linux/pagemap.h>
  13 #include <linux/backing-dev.h>
  14 #include <linux/wait.h>
  15 #include <linux/mempool.h>
  16 #include <linux/bio.h>
  17 #include <linux/module.h>
  18 #include <linux/stringify.h>
  19 #include <linux/bsg.h>
  20
  21 #include <asm/scatterlist.h>
  22
  23 struct scsi_ioctl_command;
  24
  25 struct request_queue;
  26 typedef struct request_queue request_queue_t __deprecated;
  27 struct elevator_queue;
  28 typedef struct elevator_queue elevator_t;
  29 struct request_pm_state;
  30 struct blk_trace;
  31 struct request;
  32 struct sg_io_hdr;
  33
  34 #define BLKDEV_MIN_RQ   4
  35 #define BLKDEV_MAX_RQ   128     /* Default maximum */
  36
  37 int put_io_context(struct io_context *ioc);
  38 void exit_io_context(void);
  39 struct io_context *get_io_context(gfp_t gfp_flags, int node);
  40 struct io_context *alloc_io_context(gfp_t gfp_flags, int node);
  41 void copy_io_context(struct io_context **pdst, struct io_context **psrc);
  42
  43 struct request;
  44 typedef void (rq_end_io_fn)(struct request *, int);
  45
  46 struct request_list {
  47         int count[2];
  48         int starved[2];
  49         int elvpriv;
  50         mempool_t *rq_pool;
  51         wait_queue_head_t wait[2];
  52 };
  53
  54 /*
  55  * request command types
  56  */
  57 enum rq_cmd_type_bits {
  58         REQ_TYPE_FS             = 1,    /* fs request */
  59         REQ_TYPE_BLOCK_PC,              /* scsi command */
  60         REQ_TYPE_SENSE,                 /* sense request */
  61         REQ_TYPE_PM_SUSPEND,            /* suspend request */
  62         REQ_TYPE_PM_RESUME,             /* resume request */
  63         REQ_TYPE_PM_SHUTDOWN,           /* shutdown request */
  64         REQ_TYPE_FLUSH,                 /* flush request */
  65         REQ_TYPE_SPECIAL,               /* driver defined type */
  66         REQ_TYPE_LINUX_BLOCK,           /* generic block layer message */
  67         /*
  68          * for ATA/ATAPI devices. this really doesn't belong here, ide should
  69          * use REQ_TYPE_SPECIAL and use rq->cmd[0] with the range of driver
  70          * private REQ_LB opcodes to differentiate what type of request this is
  71          */
  72         REQ_TYPE_ATA_TASKFILE,
  73         REQ_TYPE_ATA_PC,
  74 };
  75
  76 /*
  77  * For request of type REQ_TYPE_LINUX_BLOCK, rq->cmd[0] is the opcode being
  78  * sent down (similar to how REQ_TYPE_BLOCK_PC means that ->cmd[] holds a
  79  * SCSI cdb.
  80  *
  81  * 0x00 -> 0x3f are driver private, to be used for whatever purpose they need,
  82  * typically to differentiate REQ_TYPE_SPECIAL requests.
  83  *
  84  */
  85 enum {
  86         /*
  87          * just examples for now
  88          */
  89         REQ_LB_OP_EJECT = 0x40,         /* eject request */
  90         REQ_LB_OP_FLUSH = 0x41,         /* flush device */
  91 };
  92
  93 /*
  94  * request type modified bits. first three bits match BIO_RW* bits, important
  95  */
  96 enum rq_flag_bits {
  97         __REQ_RW,               /* not set, read. set, write */
  98         __REQ_FAILFAST,         /* no low level driver retries */
  99         __REQ_SORTED,           /* elevator knows about this request */
 100         __REQ_SOFTBARRIER,      /* may not be passed by ioscheduler */
 101         __REQ_HARDBARRIER,      /* may not be passed by drive either */
 102         __REQ_FUA,              /* forced unit access */
 103         __REQ_NOMERGE,          /* don't touch this for merging */
 104         __REQ_STARTED,          /* drive already may have started this one */
 105         __REQ_DONTPREP,         /* don't call prep for this one */
 106         __REQ_QUEUED,           /* uses queueing */
 107         __REQ_ELVPRIV,          /* elevator private data attached */
 108         __REQ_FAILED,           /* set if the request failed */
 109         __REQ_QUIET,            /* don't worry about errors */
 110         __REQ_PREEMPT,          /* set for "ide_preempt" requests */
 111         __REQ_ORDERED_COLOR,    /* is before or after barrier */
 112         __REQ_RW_SYNC,          /* request is sync (O_DIRECT) */
 113         __REQ_ALLOCED,          /* request came from our alloc pool */
 114         __REQ_RW_META,          /* metadata io request */
 115         __REQ_COPY_USER,        /* contains copies of user pages */
 116         __REQ_NR_BITS,          /* stops here */
 117 };
 118
 119 #define REQ_RW          (1 << __REQ_RW)
 120 #define REQ_FAILFAST    (1 << __REQ_FAILFAST)
 121 #define REQ_SORTED      (1 << __REQ_SORTED)
 122 #define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER)
 123 #define REQ_HARDBARRIER (1 << __REQ_HARDBARRIER)
 124 #define REQ_FUA         (1 << __REQ_FUA)
 125 #define REQ_NOMERGE     (1 << __REQ_NOMERGE)
 126 #define REQ_STARTED     (1 << __REQ_STARTED)
 127 #define REQ_DONTPREP    (1 << __REQ_DONTPREP)
 128 #define REQ_QUEUED      (1 << __REQ_QUEUED)
 129 #define REQ_ELVPRIV     (1 << __REQ_ELVPRIV)
 130 #define REQ_FAILED      (1 << __REQ_FAILED)
 131 #define REQ_QUIET       (1 << __REQ_QUIET)
 132 #define REQ_PREEMPT     (1 << __REQ_PREEMPT)
 133 #define REQ_ORDERED_COLOR       (1 << __REQ_ORDERED_COLOR)
 134 #define REQ_RW_SYNC     (1 << __REQ_RW_SYNC)
 135 #define REQ_ALLOCED     (1 << __REQ_ALLOCED)
 136 #define REQ_RW_META     (1 << __REQ_RW_META)
 137 #define REQ_COPY_USER   (1 << __REQ_COPY_USER)
 138
 139 #define BLK_MAX_CDB     16
 140
 141 /*
 142  * try to put the fields that are referenced together in the same cacheline.
 143  * if you modify this structure, be sure to check block/blk-core.c:rq_init()
 144  * as well!
 145  */
 146 struct request {
 147         struct list_head queuelist;
 148         struct list_head donelist;
 149
 150         struct request_queue *q;
 151
 152         unsigned int cmd_flags;
 153         enum rq_cmd_type_bits cmd_type;
 154
 155         /* Maintain bio traversal state for part by part I/O submission.
 156          * hard_* are block layer internals, no driver should touch them!
 157          */
 158
 159         sector_t sector;                /* next sector to submit */
 160         sector_t hard_sector;           /* next sector to complete */
 161         unsigned long nr_sectors;       /* no. of sectors left to submit */
 162         unsigned long hard_nr_sectors;  /* no. of sectors left to complete */
 163         /* no. of sectors left to submit in the current segment */
 164         unsigned int current_nr_sectors;
 165
 166         /* no. of sectors left to complete in the current segment */
 167         unsigned int hard_cur_sectors;
 168
 169         struct bio *bio;
 170         struct bio *biotail;
 171
 172         struct hlist_node hash; /* merge hash */
 173         /*
 174          * The rb_node is only used inside the io scheduler, requests
 175          * are pruned when moved to the dispatch queue. So let the
 176          * completion_data share space with the rb_node.
 177          */
 178         union {
 179                 struct rb_node rb_node; /* sort/lookup */
 180                 void *completion_data;
 181         };
 182
 183         /*
 184          * two pointers are available for the IO schedulers, if they need
 185          * more they have to dynamically allocate it.
 186          */
 187         void *elevator_private;
 188         void *elevator_private2;
 189
 190         struct gendisk *rq_disk;
 191         unsigned long start_time;
 192
 193         /* Number of scatter-gather DMA addr+len pairs after
 194          * physical address coalescing is performed.
 195          */
 196         unsigned short nr_phys_segments;
 197
 198         /* Number of scatter-gather addr+len pairs after
 199          * physical and DMA remapping hardware coalescing is performed.
 200          * This is the number of scatter-gather entries the driver
 201          * will actually have to deal with after DMA mapping is done.
 202          */
 203         unsigned short nr_hw_segments;
 204
 205         unsigned short ioprio;
 206
 207         void *special;
 208         char *buffer;
 209
 210         int tag;
 211         int errors;
 212
 213         int ref_count;
 214
 215         /*
 216          * when request is used as a packet command carrier
 217          */
 218         unsigned int cmd_len;
 219         unsigned char cmd[BLK_MAX_CDB];
 220
 221         unsigned int data_len;
 222         unsigned int extra_len; /* length of alignment and padding */
 223         unsigned int sense_len;
 224         void *data;
 225         void *sense;
 226
 227         unsigned int timeout;
 228         int retries;
 229
 230         /*
 231          * completion callback.
 232          */
 233         rq_end_io_fn *end_io;
 234         void *end_io_data;
 235
 236         /* for bidi */
 237         struct request *next_rq;
 238 };
 239
 240 /*
 241  * State information carried for REQ_TYPE_PM_SUSPEND and REQ_TYPE_PM_RESUME
 242  * requests. Some step values could eventually be made generic.
 243  */
 244 struct request_pm_state
 245 {
 246         /* PM state machine step value, currently driver specific */
 247         int     pm_step;
 248         /* requested PM state value (S1, S2, S3, S4, ...) */
 249         u32     pm_state;
 250         void*   data;           /* for driver use */
 251 };
 252
 253 #include <linux/elevator.h>
 254
 255 typedef void (request_fn_proc) (struct request_queue *q);
 256 typedef int (make_request_fn) (struct request_queue *q, struct bio *bio);
 257 typedef int (prep_rq_fn) (struct request_queue *, struct request *);
 258 typedef void (unplug_fn) (struct request_queue *);
 259
 260 struct bio_vec;
 261 typedef int (merge_bvec_fn) (struct request_queue *, struct bio *, struct bio_vec *);
 262 typedef void (prepare_flush_fn) (struct request_queue *, struct request *);
 263 typedef void (softirq_done_fn)(struct request *);
 264 typedef int (dma_drain_needed_fn)(struct request *);
 265
 266 enum blk_queue_state {
 267         Queue_down,
 268         Queue_up,
 269 };
 270
 271 struct blk_queue_tag {
 272         struct request **tag_index;     /* map of busy tags */
 273         unsigned long *tag_map;         /* bit map of free/busy tags */
 274         int busy;                       /* current depth */
 275         int max_depth;                  /* what we will send to device */
 276         int real_max_depth;             /* what the array can hold */
 277         atomic_t refcnt;                /* map can be shared */
 278 };
 279
 280 struct request_queue
 281 {
 282         /*
 283          * Together with queue_head for cacheline sharing
 284          */
 285         struct list_head        queue_head;
 286         struct request          *last_merge;
 287         elevator_t              *elevator;
 288
 289         /*
 290          * the queue request freelist, one for reads and one for writes
 291          */
 292         struct request_list     rq;
 293
 294         request_fn_proc         *request_fn;
 295         make_request_fn         *make_request_fn;
 296         prep_rq_fn              *prep_rq_fn;
 297         unplug_fn               *unplug_fn;
 298         merge_bvec_fn           *merge_bvec_fn;
 299         prepare_flush_fn        *prepare_flush_fn;
 300         softirq_done_fn         *softirq_done_fn;
 301         dma_drain_needed_fn     *dma_drain_needed;
 302
 303         /*
 304          * Dispatch queue sorting
 305          */
 306         sector_t                end_sector;
 307         struct request          *boundary_rq;
 308
 309         /*
 310          * Auto-unplugging state
 311          */
 312         struct timer_list       unplug_timer;
 313         int                     unplug_thresh;  /* After this many requests */
 314         unsigned long           unplug_delay;   /* After this many jiffies */
 315         struct work_struct      unplug_work;
 316
 317         struct backing_dev_info backing_dev_info;
 318
 319         /*
 320          * The queue owner gets to use this for whatever they like.
 321          * ll_rw_blk doesn't touch it.
 322          */
 323         void                    *queuedata;
 324
 325         /*
 326          * queue needs bounce pages for pages above this limit
 327          */
 328         unsigned long           bounce_pfn;
 329         gfp_t                   bounce_gfp;
 330
 331         /*
 332          * various queue flags, see QUEUE_* below
 333          */
 334         unsigned long           queue_flags;
 335
 336         /*
 337          * protects queue structures from reentrancy. ->__queue_lock should
 338          * _never_ be used directly, it is queue private. always use
 339          * ->queue_lock.
 340          */
 341         spinlock_t              __queue_lock;
 342         spinlock_t              *queue_lock;
 343
 344         /*
 345          * queue kobject
 346          */
 347         struct kobject kobj;
 348
 349         /*
 350          * queue settings
 351          */
 352         unsigned long           nr_requests;    /* Max # of requests */
 353         unsigned int            nr_congestion_on;
 354         unsigned int            nr_congestion_off;
 355         unsigned int            nr_batching;
 356
 357         unsigned int            max_sectors;
 358         unsigned int            max_hw_sectors;
 359         unsigned short          max_phys_segments;
 360         unsigned short          max_hw_segments;
 361         unsigned short          hardsect_size;
 362         unsigned int            max_segment_size;
 363
 364         unsigned long           seg_boundary_mask;
 365         void                    *dma_drain_buffer;
 366         unsigned int            dma_drain_size;
 367         unsigned int            dma_pad_mask;
 368         unsigned int            dma_alignment;
 369
 370         struct blk_queue_tag    *queue_tags;
 371         struct list_head        tag_busy_list;
 372
 373         unsigned int            nr_sorted;
 374         unsigned int            in_flight;
 375
 376         /*
 377          * sg stuff
 378          */
 379         unsigned int            sg_timeout;
 380         unsigned int            sg_reserved_size;
 381         int                     node;
 382 #ifdef CONFIG_BLK_DEV_IO_TRACE
 383         struct blk_trace        *blk_trace;
 384 #endif
 385         /*
 386          * reserved for flush operations
 387          */
 388         unsigned int            ordered, next_ordered, ordseq;
 389         int                     orderr, ordcolor;
 390         struct request          pre_flush_rq, bar_rq, post_flush_rq;
 391         struct request          *orig_bar_rq;
 392
 393         struct mutex            sysfs_lock;
 394
 395 #if defined(CONFIG_BLK_DEV_BSG)
 396         struct bsg_class_device bsg_dev;
 397 #endif
 398 };
 399
 400 #define QUEUE_FLAG_CLUSTER      0       /* cluster several segments into 1 */
 401 #define QUEUE_FLAG_QUEUED       1       /* uses generic tag queueing */
 402 #define QUEUE_FLAG_STOPPED      2       /* queue is stopped */
 403 #define QUEUE_FLAG_READFULL     3       /* read queue has been filled */
 404 #define QUEUE_FLAG_WRITEFULL    4       /* write queue has been filled */
 405 #define QUEUE_FLAG_DEAD         5       /* queue being torn down */
 406 #define QUEUE_FLAG_REENTER      6       /* Re-entrancy avoidance */
 407 #define QUEUE_FLAG_PLUGGED      7       /* queue is plugged */
 408 #define QUEUE_FLAG_ELVSWITCH    8       /* don't use elevator, just do FIFO */
 409 #define QUEUE_FLAG_BIDI         9       /* queue supports bidi requests */
 410
 411 enum {
 412         /*
 413          * Hardbarrier is supported with one of the following methods.
 414          *
 415          * NONE         : hardbarrier unsupported
 416          * DRAIN        : ordering by draining is enough
 417          * DRAIN_FLUSH  : ordering by draining w/ pre and post flushes
 418          * DRAIN_FUA    : ordering by draining w/ pre flush and FUA write
 419          * TAG          : ordering by tag is enough
 420          * TAG_FLUSH    : ordering by tag w/ pre and post flushes
 421          * TAG_FUA      : ordering by tag w/ pre flush and FUA write
 422          */
 423         QUEUE_ORDERED_NONE      = 0x00,
 424         QUEUE_ORDERED_DRAIN     = 0x01,
 425         QUEUE_ORDERED_TAG       = 0x02,
 426
 427         QUEUE_ORDERED_PREFLUSH  = 0x10,
 428         QUEUE_ORDERED_POSTFLUSH = 0x20,
 429         QUEUE_ORDERED_FUA       = 0x40,
 430
 431         QUEUE_ORDERED_DRAIN_FLUSH = QUEUE_ORDERED_DRAIN |
 432                         QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH,
 433         QUEUE_ORDERED_DRAIN_FUA = QUEUE_ORDERED_DRAIN |
 434                         QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_FUA,
 435         QUEUE_ORDERED_TAG_FLUSH = QUEUE_ORDERED_TAG |
 436                         QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH,
 437         QUEUE_ORDERED_TAG_FUA   = QUEUE_ORDERED_TAG |
 438                         QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_FUA,
 439
 440         /*
 441          * Ordered operation sequence
 442          */
 443         QUEUE_ORDSEQ_STARTED    = 0x01, /* flushing in progress */
 444         QUEUE_ORDSEQ_DRAIN      = 0x02, /* waiting for the queue to be drained */
 445         QUEUE_ORDSEQ_PREFLUSH   = 0x04, /* pre-flushing in progress */
 446         QUEUE_ORDSEQ_BAR        = 0x08, /* original barrier req in progress */
 447         QUEUE_ORDSEQ_POSTFLUSH  = 0x10, /* post-flushing in progress */
 448         QUEUE_ORDSEQ_DONE       = 0x20,
 449 };
 450
 451 #define blk_queue_plugged(q)    test_bit(QUEUE_FLAG_PLUGGED, &(q)->queue_flags)
 452 #define blk_queue_tagged(q)     test_bit(QUEUE_FLAG_QUEUED, &(q)->queue_flags)
 453 #define blk_queue_stopped(q)    test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
 454 #define blk_queue_flushing(q)   ((q)->ordseq)
 455
 456 #define blk_fs_request(rq)      ((rq)->cmd_type == REQ_TYPE_FS)
 457 #define blk_pc_request(rq)      ((rq)->cmd_type == REQ_TYPE_BLOCK_PC)
 458 #define blk_special_request(rq) ((rq)->cmd_type == REQ_TYPE_SPECIAL)
 459 #define blk_sense_request(rq)   ((rq)->cmd_type == REQ_TYPE_SENSE)
 460
 461 #define blk_noretry_request(rq) ((rq)->cmd_flags & REQ_FAILFAST)
 462 #define blk_rq_started(rq)      ((rq)->cmd_flags & REQ_STARTED)
 463
 464 #define blk_account_rq(rq)      (blk_rq_started(rq) && blk_fs_request(rq))
 465
 466 #define blk_pm_suspend_request(rq)      ((rq)->cmd_type == REQ_TYPE_PM_SUSPEND)
 467 #define blk_pm_resume_request(rq)       ((rq)->cmd_type == REQ_TYPE_PM_RESUME)
 468 #define blk_pm_request(rq)      \
 469         (blk_pm_suspend_request(rq) || blk_pm_resume_request(rq))
 470
 471 #define blk_sorted_rq(rq)       ((rq)->cmd_flags & REQ_SORTED)
 472 #define blk_barrier_rq(rq)      ((rq)->cmd_flags & REQ_HARDBARRIER)
 473 #define blk_fua_rq(rq)          ((rq)->cmd_flags & REQ_FUA)
 474 #define blk_bidi_rq(rq)         ((rq)->next_rq != NULL)
 475 #define blk_empty_barrier(rq)   (blk_barrier_rq(rq) && blk_fs_request(rq) && !(rq)->hard_nr_sectors)
 476 /* rq->queuelist of dequeued request must be list_empty() */
 477 #define blk_queued_rq(rq)       (!list_empty(&(rq)->queuelist))
 478
 479 #define list_entry_rq(ptr)      list_entry((ptr), struct request, queuelist)
 480
 481 #define rq_data_dir(rq)         ((rq)->cmd_flags & 1)
 482
 483 /*
 484  * We regard a request as sync, if it's a READ or a SYNC write.
 485  */
 486 #define rq_is_sync(rq)          (rq_data_dir((rq)) == READ || (rq)->cmd_flags & REQ_RW_SYNC)
 487 #define rq_is_meta(rq)          ((rq)->cmd_flags & REQ_RW_META)
 488
 489 static inline int blk_queue_full(struct request_queue *q, int rw)
 490 {
 491         if (rw == READ)
 492                 return test_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 493         return test_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 494 }
 495
 496 static inline void blk_set_queue_full(struct request_queue *q, int rw)
 497 {
 498         if (rw == READ)
 499                 set_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 500         else
 501                 set_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 502 }
 503
 504 static inline void blk_clear_queue_full(struct request_queue *q, int rw)
 505 {
 506         if (rw == READ)
 507                 clear_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 508         else
 509                 clear_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 510 }
 511
 512
 513 /*
 514  * mergeable request must not have _NOMERGE or _BARRIER bit set, nor may
 515  * it already be started by driver.
 516  */
 517 #define RQ_NOMERGE_FLAGS        \
 518         (REQ_NOMERGE | REQ_STARTED | REQ_HARDBARRIER | REQ_SOFTBARRIER)
 519 #define rq_mergeable(rq)        \
 520         (!((rq)->cmd_flags & RQ_NOMERGE_FLAGS) && blk_fs_request((rq)))
 521
 522 /*
 523  * q->prep_rq_fn return values
 524  */
 525 #define BLKPREP_OK              0       /* serve it */
 526 #define BLKPREP_KILL            1       /* fatal error, kill */
 527 #define BLKPREP_DEFER           2       /* leave on queue */
 528
 529 extern unsigned long blk_max_low_pfn, blk_max_pfn;
 530
 531 /*
 532  * standard bounce addresses:
 533  *
 534  * BLK_BOUNCE_HIGH      : bounce all highmem pages
 535  * BLK_BOUNCE_ANY       : don't bounce anything
 536  * BLK_BOUNCE_ISA       : bounce pages above ISA DMA boundary
 537  */
 538
 539 #if BITS_PER_LONG == 32
 540 #define BLK_BOUNCE_HIGH         ((u64)blk_max_low_pfn << PAGE_SHIFT)
 541 #else
 542 #define BLK_BOUNCE_HIGH         -1ULL
 543 #endif
 544 #define BLK_BOUNCE_ANY          (-1ULL)
 545 #define BLK_BOUNCE_ISA          (ISA_DMA_THRESHOLD)
 546
 547 /*
 548  * default timeout for SG_IO if none specified
 549  */
 550 #define BLK_DEFAULT_SG_TIMEOUT  (60 * HZ)
 551
 552 #ifdef CONFIG_BOUNCE
 553 extern int init_emergency_isa_pool(void);
 554 extern void blk_queue_bounce(struct request_queue *q, struct bio **bio);
 555 #else
 556 static inline int init_emergency_isa_pool(void)
 557 {
 558         return 0;
 559 }
 560 static inline void blk_queue_bounce(struct request_queue *q, struct bio **bio)
 561 {
 562 }
 563 #endif /* CONFIG_MMU */
 564
 565 struct req_iterator {
 566         int i;
 567         struct bio *bio;
 568 };
 569
 570 /* This should not be used directly - use rq_for_each_segment */
 571 #define __rq_for_each_bio(_bio, rq)     \
 572         if ((rq->bio))                  \
 573                 for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)
 574
 575 #define rq_for_each_segment(bvl, _rq, _iter)                    \
 576         __rq_for_each_bio(_iter.bio, _rq)                       \
 577                 bio_for_each_segment(bvl, _iter.bio, _iter.i)
 578
 579 #define rq_iter_last(rq, _iter)                                 \
 580                 (_iter.bio->bi_next == NULL && _iter.i == _iter.bio->bi_vcnt-1)
 581
 582 extern int blk_register_queue(struct gendisk *disk);
 583 extern void blk_unregister_queue(struct gendisk *disk);
 584 extern void register_disk(struct gendisk *dev);
 585 extern void generic_make_request(struct bio *bio);
 586 extern void blk_put_request(struct request *);
 587 extern void __blk_put_request(struct request_queue *, struct request *);
 588 extern void blk_end_sync_rq(struct request *rq, int error);
 589 extern struct request *blk_get_request(struct request_queue *, int, gfp_t);
 590 extern void blk_insert_request(struct request_queue *, struct request *, int, void *);
 591 extern void blk_requeue_request(struct request_queue *, struct request *);
 592 extern void blk_plug_device(struct request_queue *);
 593 extern int blk_remove_plug(struct request_queue *);
 594 extern void blk_recount_segments(struct request_queue *, struct bio *);
 595 extern int scsi_cmd_ioctl(struct file *, struct request_queue *,
 596                           struct gendisk *, unsigned int, void __user *);
 597 extern int sg_scsi_ioctl(struct file *, struct request_queue *,
 598                 struct gendisk *, struct scsi_ioctl_command __user *);
 599
 600 /*
 601  * Temporary export, until SCSI gets fixed up.
 602  */
 603 extern int blk_rq_append_bio(struct request_queue *q, struct request *rq,
 604                              struct bio *bio);
 605
 606 /*
 607  * A queue has just exitted congestion.  Note this in the global counter of
 608  * congested queues, and wake up anyone who was waiting for requests to be
 609  * put back.
 610  */
 611 static inline void blk_clear_queue_congested(struct request_queue *q, int rw)
 612 {
 613         clear_bdi_congested(&q->backing_dev_info, rw);
 614 }
 615
 616 /*
 617  * A queue has just entered congestion.  Flag that in the queue's VM-visible
 618  * state flags and increment the global gounter of congested queues.
 619  */
 620 static inline void blk_set_queue_congested(struct request_queue *q, int rw)
 621 {
 622         set_bdi_congested(&q->backing_dev_info, rw);
 623 }
 624
 625 extern void blk_start_queue(struct request_queue *q);
 626 extern void blk_stop_queue(struct request_queue *q);
 627 extern void blk_sync_queue(struct request_queue *q);
 628 extern void __blk_stop_queue(struct request_queue *q);
 629 extern void blk_run_queue(struct request_queue *);
 630 extern void blk_start_queueing(struct request_queue *);
 631 extern int blk_rq_map_user(struct request_queue *, struct request *, void __user *, unsigned long);
 632 extern int blk_rq_unmap_user(struct bio *);
 633 extern int blk_rq_map_kern(struct request_queue *, struct request *, void *, unsigned int, gfp_t);
 634 extern int blk_rq_map_user_iov(struct request_queue *, struct request *,
 635                                struct sg_iovec *, int, unsigned int);
 636 extern int blk_execute_rq(struct request_queue *, struct gendisk *,
 637                           struct request *, int);
 638 extern void blk_execute_rq_nowait(struct request_queue *, struct gendisk *,
 639                                   struct request *, int, rq_end_io_fn *);
 640 extern int blk_verify_command(unsigned char *, int);
 641 extern void blk_unplug(struct request_queue *q);
 642
 643 static inline struct request_queue *bdev_get_queue(struct block_device *bdev)
 644 {
 645         return bdev->bd_disk->queue;
 646 }
 647
 648 static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
 649                                        struct page *page)
 650 {
 651         if (bdi && bdi->unplug_io_fn)
 652                 bdi->unplug_io_fn(bdi, page);
 653 }
 654
 655 static inline void blk_run_address_space(struct address_space *mapping)
 656 {
 657         if (mapping)
 658                 blk_run_backing_dev(mapping->backing_dev_info, NULL);
 659 }
 660
 661 /*
 662  * blk_end_request() and friends.
 663  * __blk_end_request() and end_request() must be called with
 664  * the request queue spinlock acquired.
 665  *
 666  * Several drivers define their own end_request and call
 667  * blk_end_request() for parts of the original function.
 668  * This prevents code duplication in drivers.
 669  */
 670 extern int blk_end_request(struct request *rq, int error,
 671                                 unsigned int nr_bytes);
 672 extern int __blk_end_request(struct request *rq, int error,
 673                                 unsigned int nr_bytes);
 674 extern int blk_end_bidi_request(struct request *rq, int error,
 675                                 unsigned int nr_bytes, unsigned int bidi_bytes);
 676 extern void end_request(struct request *, int);
 677 extern void end_queued_request(struct request *, int);
 678 extern void end_dequeued_request(struct request *, int);
 679 extern int blk_end_request_callback(struct request *rq, int error,
 680                                 unsigned int nr_bytes,
 681                                 int (drv_callback)(struct request *));
 682 extern void blk_complete_request(struct request *);
 683
 684 /*
 685  * blk_end_request() takes bytes instead of sectors as a complete size.
 686  * blk_rq_bytes() returns bytes left to complete in the entire request.
 687  * blk_rq_cur_bytes() returns bytes left to complete in the current segment.
 688  */
 689 extern unsigned int blk_rq_bytes(struct request *rq);
 690 extern unsigned int blk_rq_cur_bytes(struct request *rq);
 691
 692 static inline void blkdev_dequeue_request(struct request *req)
 693 {
 694         elv_dequeue_request(req->q, req);
 695 }
 696
 697 /*
 698  * Access functions for manipulating queue properties
 699  */
 700 extern struct request_queue *blk_init_queue_node(request_fn_proc *rfn,
 701                                         spinlock_t *lock, int node_id);
 702 extern struct request_queue *blk_init_queue(request_fn_proc *, spinlock_t *);
 703 extern void blk_cleanup_queue(struct request_queue *);
 704 extern void blk_queue_make_request(struct request_queue *, make_request_fn *);
 705 extern void blk_queue_bounce_limit(struct request_queue *, u64);
 706 extern void blk_queue_max_sectors(struct request_queue *, unsigned int);
 707 extern void blk_queue_max_phys_segments(struct request_queue *, unsigned short);
 708 extern void blk_queue_max_hw_segments(struct request_queue *, unsigned short);
 709 extern void blk_queue_max_segment_size(struct request_queue *, unsigned int);
 710 extern void blk_queue_hardsect_size(struct request_queue *, unsigned short);
 711 extern void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b);
 712 extern void blk_queue_dma_pad(struct request_queue *, unsigned int);
 713 extern int blk_queue_dma_drain(struct request_queue *q,
 714                                dma_drain_needed_fn *dma_drain_needed,
 715                                void *buf, unsigned int size);
 716 extern void blk_queue_segment_boundary(struct request_queue *, unsigned long);
 717 extern void blk_queue_prep_rq(struct request_queue *, prep_rq_fn *pfn);
 718 extern void blk_queue_merge_bvec(struct request_queue *, merge_bvec_fn *);
 719 extern void blk_queue_dma_alignment(struct request_queue *, int);
 720 extern void blk_queue_update_dma_alignment(struct request_queue *, int);
 721 extern void blk_queue_softirq_done(struct request_queue *, softirq_done_fn *);
 722 extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);
 723 extern int blk_queue_ordered(struct request_queue *, unsigned, prepare_flush_fn *);
 724 extern int blk_do_ordered(struct request_queue *, struct request **);
 725 extern unsigned blk_ordered_cur_seq(struct request_queue *);
 726 extern unsigned blk_ordered_req_seq(struct request *);
 727 extern void blk_ordered_complete_seq(struct request_queue *, unsigned, int);
 728
 729 extern int blk_rq_map_sg(struct request_queue *, struct request *, struct scatterlist *);
 730 extern void blk_dump_rq_flags(struct request *, char *);
 731 extern void generic_unplug_device(struct request_queue *);
 732 extern void __generic_unplug_device(struct request_queue *);
 733 extern long nr_blockdev_pages(void);
 734
 735 int blk_get_queue(struct request_queue *);
 736 struct request_queue *blk_alloc_queue(gfp_t);
 737 struct request_queue *blk_alloc_queue_node(gfp_t, int);
 738 extern void blk_put_queue(struct request_queue *);
 739
 740 /*
 741  * tag stuff
 742  */
 743 #define blk_queue_tag_depth(q)          ((q)->queue_tags->busy)
 744 #define blk_queue_tag_queue(q)          ((q)->queue_tags->busy < (q)->queue_tags->max_depth)
 745 #define blk_rq_tagged(rq)               ((rq)->cmd_flags & REQ_QUEUED)
 746 extern int blk_queue_start_tag(struct request_queue *, struct request *);
 747 extern struct request *blk_queue_find_tag(struct request_queue *, int);
 748 extern void blk_queue_end_tag(struct request_queue *, struct request *);
 749 extern int blk_queue_init_tags(struct request_queue *, int, struct blk_queue_tag *);
 750 extern void blk_queue_free_tags(struct request_queue *);
 751 extern int blk_queue_resize_tags(struct request_queue *, int);
 752 extern void blk_queue_invalidate_tags(struct request_queue *);
 753 extern struct blk_queue_tag *blk_init_tags(int);
 754 extern void blk_free_tags(struct blk_queue_tag *);
 755
 756 static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
 757                                                 int tag)
 758 {
 759         if (unlikely(bqt == NULL || tag >= bqt->real_max_depth))
 760                 return NULL;
 761         return bqt->tag_index[tag];
 762 }
 763
 764 extern int blkdev_issue_flush(struct block_device *, sector_t *);
 765
 766 #define MAX_PHYS_SEGMENTS 128
 767 #define MAX_HW_SEGMENTS 128
 768 #define SAFE_MAX_SECTORS 255
 769 #define BLK_DEF_MAX_SECTORS 1024
 770
 771 #define MAX_SEGMENT_SIZE        65536
 772
 773 #define blkdev_entry_to_request(entry) list_entry((entry), struct request, queuelist)
 774
 775 static inline int queue_hardsect_size(struct request_queue *q)
 776 {
 777         int retval = 512;
 778
 779         if (q && q->hardsect_size)
 780                 retval = q->hardsect_size;
 781
 782         return retval;
 783 }
 784
 785 static inline int bdev_hardsect_size(struct block_device *bdev)
 786 {
 787         return queue_hardsect_size(bdev_get_queue(bdev));
 788 }
 789
 790 static inline int queue_dma_alignment(struct request_queue *q)
 791 {
 792         return q ? q->dma_alignment : 511;
 793 }
 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_work(struct work_struct *work);
 823
 824 #define MODULE_ALIAS_BLOCKDEV(major,minor) \
 825         MODULE_ALIAS("block-major-" __stringify(major) "-" __stringify(minor))
 826 #define MODULE_ALIAS_BLOCKDEV_MAJOR(major) \
 827         MODULE_ALIAS("block-major-" __stringify(major) "-*")
 828
 829
 830 #else /* CONFIG_BLOCK */
 831 /*
 832  * stubs for when the block layer is configured out
 833  */
 834 #define buffer_heads_over_limit 0
 835
 836 static inline long nr_blockdev_pages(void)
 837 {
 838         return 0;
 839 }
 840
 841 static inline void exit_io_context(void)
 842 {
 843 }
 844
 845 struct io_context;
 846 static inline int put_io_context(struct io_context *ioc)
 847 {
 848         return 1;
 849 }
 850
 851
 852 #endif /* CONFIG_BLOCK */
 853
 854 #endif