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 #ifdef CONFIG_LBD
  24 # include <asm/div64.h>
  25 # define sector_div(a, b) do_div(a, b)
  26 #else
  27 # define sector_div(n, b)( \
  28 { \
  29         int _res; \
  30         _res = (n) % (b); \
  31         (n) /= (b); \
  32         _res; \
  33 } \
  34 )
  35 #endif
  36
  37 struct scsi_ioctl_command;
  38
  39 struct request_queue;
  40 typedef struct request_queue request_queue_t __deprecated;
  41 struct elevator_queue;
  42 typedef struct elevator_queue elevator_t;
  43 struct request_pm_state;
  44 struct blk_trace;
  45 struct request;
  46 struct sg_io_hdr;
  47
  48 #define BLKDEV_MIN_RQ   4
  49 #define BLKDEV_MAX_RQ   128     /* Default maximum */
  50
  51 /*
  52  * This is the per-process anticipatory I/O scheduler state.
  53  */
  54 struct as_io_context {
  55         spinlock_t lock;
  56
  57         void (*dtor)(struct as_io_context *aic); /* destructor */
  58         void (*exit)(struct as_io_context *aic); /* called on task exit */
  59
  60         unsigned long state;
  61         atomic_t nr_queued; /* queued reads & sync writes */
  62         atomic_t nr_dispatched; /* number of requests gone to the drivers */
  63
  64         /* IO History tracking */
  65         /* Thinktime */
  66         unsigned long last_end_request;
  67         unsigned long ttime_total;
  68         unsigned long ttime_samples;
  69         unsigned long ttime_mean;
  70         /* Layout pattern */
  71         unsigned int seek_samples;
  72         sector_t last_request_pos;
  73         u64 seek_total;
  74         sector_t seek_mean;
  75 };
  76
  77 struct cfq_queue;
  78 struct cfq_io_context {
  79         struct rb_node rb_node;
  80         void *key;
  81
  82         struct cfq_queue *cfqq[2];
  83
  84         struct io_context *ioc;
  85
  86         unsigned long last_end_request;
  87         sector_t last_request_pos;
  88
  89         unsigned long ttime_total;
  90         unsigned long ttime_samples;
  91         unsigned long ttime_mean;
  92
  93         unsigned int seek_samples;
  94         u64 seek_total;
  95         sector_t seek_mean;
  96
  97         struct list_head queue_list;
  98
  99         void (*dtor)(struct io_context *); /* destructor */
 100         void (*exit)(struct io_context *); /* called on task exit */
 101 };
 102
 103 /*
 104  * This is the per-process I/O subsystem state.  It is refcounted and
 105  * kmalloc'ed. Currently all fields are modified in process io context
 106  * (apart from the atomic refcount), so require no locking.
 107  */
 108 struct io_context {
 109         atomic_t refcount;
 110         struct task_struct *task;
 111
 112         unsigned int ioprio_changed;
 113
 114         /*
 115          * For request batching
 116          */
 117         unsigned long last_waited; /* Time last woken after wait for request */
 118         int nr_batch_requests;     /* Number of requests left in the batch */
 119
 120         struct as_io_context *aic;
 121         struct rb_root cic_root;
 122         void *ioc_data;
 123 };
 124
 125 void put_io_context(struct io_context *ioc);
 126 void exit_io_context(void);
 127 struct io_context *get_io_context(gfp_t gfp_flags, int node);
 128 void copy_io_context(struct io_context **pdst, struct io_context **psrc);
 129 void swap_io_context(struct io_context **ioc1, struct io_context **ioc2);
 130
 131 struct request;
 132 typedef void (rq_end_io_fn)(struct request *, int);
 133
 134 struct request_list {
 135         int count[2];
 136         int starved[2];
 137         int elvpriv;
 138         mempool_t *rq_pool;
 139         wait_queue_head_t wait[2];
 140 };
 141
 142 /*
 143  * request command types
 144  */
 145 enum rq_cmd_type_bits {
 146         REQ_TYPE_FS             = 1,    /* fs request */
 147         REQ_TYPE_BLOCK_PC,              /* scsi command */
 148         REQ_TYPE_SENSE,                 /* sense request */
 149         REQ_TYPE_PM_SUSPEND,            /* suspend request */
 150         REQ_TYPE_PM_RESUME,             /* resume request */
 151         REQ_TYPE_PM_SHUTDOWN,           /* shutdown request */
 152         REQ_TYPE_FLUSH,                 /* flush request */
 153         REQ_TYPE_SPECIAL,               /* driver defined type */
 154         REQ_TYPE_LINUX_BLOCK,           /* generic block layer message */
 155         /*
 156          * for ATA/ATAPI devices. this really doesn't belong here, ide should
 157          * use REQ_TYPE_SPECIAL and use rq->cmd[0] with the range of driver
 158          * private REQ_LB opcodes to differentiate what type of request this is
 159          */
 160         REQ_TYPE_ATA_CMD,
 161         REQ_TYPE_ATA_TASK,
 162         REQ_TYPE_ATA_TASKFILE,
 163         REQ_TYPE_ATA_PC,
 164 };
 165
 166 /*
 167  * For request of type REQ_TYPE_LINUX_BLOCK, rq->cmd[0] is the opcode being
 168  * sent down (similar to how REQ_TYPE_BLOCK_PC means that ->cmd[] holds a
 169  * SCSI cdb.
 170  *
 171  * 0x00 -> 0x3f are driver private, to be used for whatever purpose they need,
 172  * typically to differentiate REQ_TYPE_SPECIAL requests.
 173  *
 174  */
 175 enum {
 176         /*
 177          * just examples for now
 178          */
 179         REQ_LB_OP_EJECT = 0x40,         /* eject request */
 180         REQ_LB_OP_FLUSH = 0x41,         /* flush device */
 181 };
 182
 183 /*
 184  * request type modified bits. first three bits match BIO_RW* bits, important
 185  */
 186 enum rq_flag_bits {
 187         __REQ_RW,               /* not set, read. set, write */
 188         __REQ_FAILFAST,         /* no low level driver retries */
 189         __REQ_SORTED,           /* elevator knows about this request */
 190         __REQ_SOFTBARRIER,      /* may not be passed by ioscheduler */
 191         __REQ_HARDBARRIER,      /* may not be passed by drive either */
 192         __REQ_FUA,              /* forced unit access */
 193         __REQ_NOMERGE,          /* don't touch this for merging */
 194         __REQ_STARTED,          /* drive already may have started this one */
 195         __REQ_DONTPREP,         /* don't call prep for this one */
 196         __REQ_QUEUED,           /* uses queueing */
 197         __REQ_ELVPRIV,          /* elevator private data attached */
 198         __REQ_FAILED,           /* set if the request failed */
 199         __REQ_QUIET,            /* don't worry about errors */
 200         __REQ_PREEMPT,          /* set for "ide_preempt" requests */
 201         __REQ_ORDERED_COLOR,    /* is before or after barrier */
 202         __REQ_RW_SYNC,          /* request is sync (O_DIRECT) */
 203         __REQ_ALLOCED,          /* request came from our alloc pool */
 204         __REQ_RW_META,          /* metadata io request */
 205         __REQ_NR_BITS,          /* stops here */
 206 };
 207
 208 #define REQ_RW          (1 << __REQ_RW)
 209 #define REQ_FAILFAST    (1 << __REQ_FAILFAST)
 210 #define REQ_SORTED      (1 << __REQ_SORTED)
 211 #define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER)
 212 #define REQ_HARDBARRIER (1 << __REQ_HARDBARRIER)
 213 #define REQ_FUA         (1 << __REQ_FUA)
 214 #define REQ_NOMERGE     (1 << __REQ_NOMERGE)
 215 #define REQ_STARTED     (1 << __REQ_STARTED)
 216 #define REQ_DONTPREP    (1 << __REQ_DONTPREP)
 217 #define REQ_QUEUED      (1 << __REQ_QUEUED)
 218 #define REQ_ELVPRIV     (1 << __REQ_ELVPRIV)
 219 #define REQ_FAILED      (1 << __REQ_FAILED)
 220 #define REQ_QUIET       (1 << __REQ_QUIET)
 221 #define REQ_PREEMPT     (1 << __REQ_PREEMPT)
 222 #define REQ_ORDERED_COLOR       (1 << __REQ_ORDERED_COLOR)
 223 #define REQ_RW_SYNC     (1 << __REQ_RW_SYNC)
 224 #define REQ_ALLOCED     (1 << __REQ_ALLOCED)
 225 #define REQ_RW_META     (1 << __REQ_RW_META)
 226
 227 #define BLK_MAX_CDB     16
 228
 229 /*
 230  * try to put the fields that are referenced together in the same cacheline
 231  */
 232 struct request {
 233         struct list_head queuelist;
 234         struct list_head donelist;
 235
 236         struct request_queue *q;
 237
 238         unsigned int cmd_flags;
 239         enum rq_cmd_type_bits cmd_type;
 240
 241         /* Maintain bio traversal state for part by part I/O submission.
 242          * hard_* are block layer internals, no driver should touch them!
 243          */
 244
 245         sector_t sector;                /* next sector to submit */
 246         sector_t hard_sector;           /* next sector to complete */
 247         unsigned long nr_sectors;       /* no. of sectors left to submit */
 248         unsigned long hard_nr_sectors;  /* no. of sectors left to complete */
 249         /* no. of sectors left to submit in the current segment */
 250         unsigned int current_nr_sectors;
 251
 252         /* no. of sectors left to complete in the current segment */
 253         unsigned int hard_cur_sectors;
 254
 255         struct bio *bio;
 256         struct bio *biotail;
 257
 258         struct hlist_node hash; /* merge hash */
 259         /*
 260          * The rb_node is only used inside the io scheduler, requests
 261          * are pruned when moved to the dispatch queue. So let the
 262          * completion_data share space with the rb_node.
 263          */
 264         union {
 265                 struct rb_node rb_node; /* sort/lookup */
 266                 void *completion_data;
 267         };
 268
 269         /*
 270          * two pointers are available for the IO schedulers, if they need
 271          * more they have to dynamically allocate it.
 272          */
 273         void *elevator_private;
 274         void *elevator_private2;
 275
 276         struct gendisk *rq_disk;
 277         unsigned long start_time;
 278
 279         /* Number of scatter-gather DMA addr+len pairs after
 280          * physical address coalescing is performed.
 281          */
 282         unsigned short nr_phys_segments;
 283
 284         /* Number of scatter-gather addr+len pairs after
 285          * physical and DMA remapping hardware coalescing is performed.
 286          * This is the number of scatter-gather entries the driver
 287          * will actually have to deal with after DMA mapping is done.
 288          */
 289         unsigned short nr_hw_segments;
 290
 291         unsigned short ioprio;
 292
 293         void *special;
 294         char *buffer;
 295
 296         int tag;
 297         int errors;
 298
 299         int ref_count;
 300
 301         /*
 302          * when request is used as a packet command carrier
 303          */
 304         unsigned int cmd_len;
 305         unsigned char cmd[BLK_MAX_CDB];
 306
 307         unsigned int data_len;
 308         unsigned int sense_len;
 309         void *data;
 310         void *sense;
 311
 312         unsigned int timeout;
 313         int retries;
 314
 315         /*
 316          * completion callback.
 317          */
 318         rq_end_io_fn *end_io;
 319         void *end_io_data;
 320
 321         /* for bidi */
 322         struct request *next_rq;
 323 };
 324
 325 /*
 326  * State information carried for REQ_TYPE_PM_SUSPEND and REQ_TYPE_PM_RESUME
 327  * requests. Some step values could eventually be made generic.
 328  */
 329 struct request_pm_state
 330 {
 331         /* PM state machine step value, currently driver specific */
 332         int     pm_step;
 333         /* requested PM state value (S1, S2, S3, S4, ...) */
 334         u32     pm_state;
 335         void*   data;           /* for driver use */
 336 };
 337
 338 #include <linux/elevator.h>
 339
 340 typedef void (request_fn_proc) (struct request_queue *q);
 341 typedef int (make_request_fn) (struct request_queue *q, struct bio *bio);
 342 typedef int (prep_rq_fn) (struct request_queue *, struct request *);
 343 typedef void (unplug_fn) (struct request_queue *);
 344
 345 struct bio_vec;
 346 typedef int (merge_bvec_fn) (struct request_queue *, struct bio *, struct bio_vec *);
 347 typedef int (issue_flush_fn) (struct request_queue *, struct gendisk *, sector_t *);
 348 typedef void (prepare_flush_fn) (struct request_queue *, struct request *);
 349 typedef void (softirq_done_fn)(struct request *);
 350
 351 enum blk_queue_state {
 352         Queue_down,
 353         Queue_up,
 354 };
 355
 356 struct blk_queue_tag {
 357         struct request **tag_index;     /* map of busy tags */
 358         unsigned long *tag_map;         /* bit map of free/busy tags */
 359         struct list_head busy_list;     /* fifo list of busy tags */
 360         int busy;                       /* current depth */
 361         int max_depth;                  /* what we will send to device */
 362         int real_max_depth;             /* what the array can hold */
 363         atomic_t refcnt;                /* map can be shared */
 364 };
 365
 366 struct request_queue
 367 {
 368         /*
 369          * Together with queue_head for cacheline sharing
 370          */
 371         struct list_head        queue_head;
 372         struct request          *last_merge;
 373         elevator_t              *elevator;
 374
 375         /*
 376          * the queue request freelist, one for reads and one for writes
 377          */
 378         struct request_list     rq;
 379
 380         request_fn_proc         *request_fn;
 381         make_request_fn         *make_request_fn;
 382         prep_rq_fn              *prep_rq_fn;
 383         unplug_fn               *unplug_fn;
 384         merge_bvec_fn           *merge_bvec_fn;
 385         issue_flush_fn          *issue_flush_fn;
 386         prepare_flush_fn        *prepare_flush_fn;
 387         softirq_done_fn         *softirq_done_fn;
 388
 389         /*
 390          * Dispatch queue sorting
 391          */
 392         sector_t                end_sector;
 393         struct request          *boundary_rq;
 394
 395         /*
 396          * Auto-unplugging state
 397          */
 398         struct timer_list       unplug_timer;
 399         int                     unplug_thresh;  /* After this many requests */
 400         unsigned long           unplug_delay;   /* After this many jiffies */
 401         struct work_struct      unplug_work;
 402
 403         struct backing_dev_info backing_dev_info;
 404
 405         /*
 406          * The queue owner gets to use this for whatever they like.
 407          * ll_rw_blk doesn't touch it.
 408          */
 409         void                    *queuedata;
 410
 411         /*
 412          * queue needs bounce pages for pages above this limit
 413          */
 414         unsigned long           bounce_pfn;
 415         gfp_t                   bounce_gfp;
 416
 417         /*
 418          * various queue flags, see QUEUE_* below
 419          */
 420         unsigned long           queue_flags;
 421
 422         /*
 423          * protects queue structures from reentrancy. ->__queue_lock should
 424          * _never_ be used directly, it is queue private. always use
 425          * ->queue_lock.
 426          */
 427         spinlock_t              __queue_lock;
 428         spinlock_t              *queue_lock;
 429
 430         /*
 431          * queue kobject
 432          */
 433         struct kobject kobj;
 434
 435         /*
 436          * queue settings
 437          */
 438         unsigned long           nr_requests;    /* Max # of requests */
 439         unsigned int            nr_congestion_on;
 440         unsigned int            nr_congestion_off;
 441         unsigned int            nr_batching;
 442
 443         unsigned int            max_sectors;
 444         unsigned int            max_hw_sectors;
 445         unsigned short          max_phys_segments;
 446         unsigned short          max_hw_segments;
 447         unsigned short          hardsect_size;
 448         unsigned int            max_segment_size;
 449
 450         unsigned long           seg_boundary_mask;
 451         unsigned int            dma_alignment;
 452
 453         struct blk_queue_tag    *queue_tags;
 454
 455         unsigned int            nr_sorted;
 456         unsigned int            in_flight;
 457
 458         /*
 459          * sg stuff
 460          */
 461         unsigned int            sg_timeout;
 462         unsigned int            sg_reserved_size;
 463         int                     node;
 464 #ifdef CONFIG_BLK_DEV_IO_TRACE
 465         struct blk_trace        *blk_trace;
 466 #endif
 467         /*
 468          * reserved for flush operations
 469          */
 470         unsigned int            ordered, next_ordered, ordseq;
 471         int                     orderr, ordcolor;
 472         struct request          pre_flush_rq, bar_rq, post_flush_rq;
 473         struct request          *orig_bar_rq;
 474
 475         struct mutex            sysfs_lock;
 476
 477 #if defined(CONFIG_BLK_DEV_BSG)
 478         struct bsg_class_device bsg_dev;
 479 #endif
 480 };
 481
 482 #define QUEUE_FLAG_CLUSTER      0       /* cluster several segments into 1 */
 483 #define QUEUE_FLAG_QUEUED       1       /* uses generic tag queueing */
 484 #define QUEUE_FLAG_STOPPED      2       /* queue is stopped */
 485 #define QUEUE_FLAG_READFULL     3       /* read queue has been filled */
 486 #define QUEUE_FLAG_WRITEFULL    4       /* write queue has been filled */
 487 #define QUEUE_FLAG_DEAD         5       /* queue being torn down */
 488 #define QUEUE_FLAG_REENTER      6       /* Re-entrancy avoidance */
 489 #define QUEUE_FLAG_PLUGGED      7       /* queue is plugged */
 490 #define QUEUE_FLAG_ELVSWITCH    8       /* don't use elevator, just do FIFO */
 491 #define QUEUE_FLAG_BIDI         9       /* queue supports bidi requests */
 492
 493 enum {
 494         /*
 495          * Hardbarrier is supported with one of the following methods.
 496          *
 497          * NONE         : hardbarrier unsupported
 498          * DRAIN        : ordering by draining is enough
 499          * DRAIN_FLUSH  : ordering by draining w/ pre and post flushes
 500          * DRAIN_FUA    : ordering by draining w/ pre flush and FUA write
 501          * TAG          : ordering by tag is enough
 502          * TAG_FLUSH    : ordering by tag w/ pre and post flushes
 503          * TAG_FUA      : ordering by tag w/ pre flush and FUA write
 504          */
 505         QUEUE_ORDERED_NONE      = 0x00,
 506         QUEUE_ORDERED_DRAIN     = 0x01,
 507         QUEUE_ORDERED_TAG       = 0x02,
 508
 509         QUEUE_ORDERED_PREFLUSH  = 0x10,
 510         QUEUE_ORDERED_POSTFLUSH = 0x20,
 511         QUEUE_ORDERED_FUA       = 0x40,
 512
 513         QUEUE_ORDERED_DRAIN_FLUSH = QUEUE_ORDERED_DRAIN |
 514                         QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH,
 515         QUEUE_ORDERED_DRAIN_FUA = QUEUE_ORDERED_DRAIN |
 516                         QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_FUA,
 517         QUEUE_ORDERED_TAG_FLUSH = QUEUE_ORDERED_TAG |
 518                         QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH,
 519         QUEUE_ORDERED_TAG_FUA   = QUEUE_ORDERED_TAG |
 520                         QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_FUA,
 521
 522         /*
 523          * Ordered operation sequence
 524          */
 525         QUEUE_ORDSEQ_STARTED    = 0x01, /* flushing in progress */
 526         QUEUE_ORDSEQ_DRAIN      = 0x02, /* waiting for the queue to be drained */
 527         QUEUE_ORDSEQ_PREFLUSH   = 0x04, /* pre-flushing in progress */
 528         QUEUE_ORDSEQ_BAR        = 0x08, /* original barrier req in progress */
 529         QUEUE_ORDSEQ_POSTFLUSH  = 0x10, /* post-flushing in progress */
 530         QUEUE_ORDSEQ_DONE       = 0x20,
 531 };
 532
 533 #define blk_queue_plugged(q)    test_bit(QUEUE_FLAG_PLUGGED, &(q)->queue_flags)
 534 #define blk_queue_tagged(q)     test_bit(QUEUE_FLAG_QUEUED, &(q)->queue_flags)
 535 #define blk_queue_stopped(q)    test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
 536 #define blk_queue_flushing(q)   ((q)->ordseq)
 537
 538 #define blk_fs_request(rq)      ((rq)->cmd_type == REQ_TYPE_FS)
 539 #define blk_pc_request(rq)      ((rq)->cmd_type == REQ_TYPE_BLOCK_PC)
 540 #define blk_special_request(rq) ((rq)->cmd_type == REQ_TYPE_SPECIAL)
 541 #define blk_sense_request(rq)   ((rq)->cmd_type == REQ_TYPE_SENSE)
 542
 543 #define blk_noretry_request(rq) ((rq)->cmd_flags & REQ_FAILFAST)
 544 #define blk_rq_started(rq)      ((rq)->cmd_flags & REQ_STARTED)
 545
 546 #define blk_account_rq(rq)      (blk_rq_started(rq) && blk_fs_request(rq))
 547
 548 #define blk_pm_suspend_request(rq)      ((rq)->cmd_type == REQ_TYPE_PM_SUSPEND)
 549 #define blk_pm_resume_request(rq)       ((rq)->cmd_type == REQ_TYPE_PM_RESUME)
 550 #define blk_pm_request(rq)      \
 551         (blk_pm_suspend_request(rq) || blk_pm_resume_request(rq))
 552
 553 #define blk_sorted_rq(rq)       ((rq)->cmd_flags & REQ_SORTED)
 554 #define blk_barrier_rq(rq)      ((rq)->cmd_flags & REQ_HARDBARRIER)
 555 #define blk_fua_rq(rq)          ((rq)->cmd_flags & REQ_FUA)
 556 #define blk_bidi_rq(rq)         ((rq)->next_rq != NULL)
 557
 558 #define list_entry_rq(ptr)      list_entry((ptr), struct request, queuelist)
 559
 560 #define rq_data_dir(rq)         ((rq)->cmd_flags & 1)
 561
 562 /*
 563  * We regard a request as sync, if it's a READ or a SYNC write.
 564  */
 565 #define rq_is_sync(rq)          (rq_data_dir((rq)) == READ || (rq)->cmd_flags & REQ_RW_SYNC)
 566 #define rq_is_meta(rq)          ((rq)->cmd_flags & REQ_RW_META)
 567
 568 static inline int blk_queue_full(struct request_queue *q, int rw)
 569 {
 570         if (rw == READ)
 571                 return test_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 572         return test_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 573 }
 574
 575 static inline void blk_set_queue_full(struct request_queue *q, int rw)
 576 {
 577         if (rw == READ)
 578                 set_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 579         else
 580                 set_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 581 }
 582
 583 static inline void blk_clear_queue_full(struct request_queue *q, int rw)
 584 {
 585         if (rw == READ)
 586                 clear_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
 587         else
 588                 clear_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
 589 }
 590
 591
 592 /*
 593  * mergeable request must not have _NOMERGE or _BARRIER bit set, nor may
 594  * it already be started by driver.
 595  */
 596 #define RQ_NOMERGE_FLAGS        \
 597         (REQ_NOMERGE | REQ_STARTED | REQ_HARDBARRIER | REQ_SOFTBARRIER)
 598 #define rq_mergeable(rq)        \
 599         (!((rq)->cmd_flags & RQ_NOMERGE_FLAGS) && blk_fs_request((rq)))
 600
 601 /*
 602  * q->prep_rq_fn return values
 603  */
 604 #define BLKPREP_OK              0       /* serve it */
 605 #define BLKPREP_KILL            1       /* fatal error, kill */
 606 #define BLKPREP_DEFER           2       /* leave on queue */
 607
 608 extern unsigned long blk_max_low_pfn, blk_max_pfn;
 609
 610 /*
 611  * standard bounce addresses:
 612  *
 613  * BLK_BOUNCE_HIGH      : bounce all highmem pages
 614  * BLK_BOUNCE_ANY       : don't bounce anything
 615  * BLK_BOUNCE_ISA       : bounce pages above ISA DMA boundary
 616  */
 617 #define BLK_BOUNCE_HIGH         ((u64)blk_max_low_pfn << PAGE_SHIFT)
 618 #define BLK_BOUNCE_ANY          ((u64)blk_max_pfn << PAGE_SHIFT)
 619 #define BLK_BOUNCE_ISA          (ISA_DMA_THRESHOLD)
 620
 621 /*
 622  * default timeout for SG_IO if none specified
 623  */
 624 #define BLK_DEFAULT_SG_TIMEOUT  (60 * HZ)
 625
 626 #ifdef CONFIG_BOUNCE
 627 extern int init_emergency_isa_pool(void);
 628 extern void blk_queue_bounce(struct request_queue *q, struct bio **bio);
 629 #else
 630 static inline int init_emergency_isa_pool(void)
 631 {
 632         return 0;
 633 }
 634 static inline void blk_queue_bounce(struct request_queue *q, struct bio **bio)
 635 {
 636 }
 637 #endif /* CONFIG_MMU */
 638
 639 struct req_iterator {
 640         int i;
 641         struct bio *bio;
 642 };
 643
 644 /* This should not be used directly - use rq_for_each_segment */
 645 #define __rq_for_each_bio(_bio, rq)     \
 646         if ((rq->bio))                  \
 647                 for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)
 648
 649 #define rq_for_each_segment(bvl, _rq, _iter)                    \
 650         __rq_for_each_bio(_iter.bio, _rq)                       \
 651                 bio_for_each_segment(bvl, _iter.bio, _iter.i)
 652
 653 #define rq_iter_last(rq, _iter)                                 \
 654                 (_iter.bio->bi_next == NULL && _iter.i == _iter.bio->bi_vcnt-1)
 655
 656 extern int blk_register_queue(struct gendisk *disk);
 657 extern void blk_unregister_queue(struct gendisk *disk);
 658 extern void register_disk(struct gendisk *dev);
 659 extern void generic_make_request(struct bio *bio);
 660 extern void blk_put_request(struct request *);
 661 extern void __blk_put_request(struct request_queue *, struct request *);
 662 extern void blk_end_sync_rq(struct request *rq, int error);
 663 extern struct request *blk_get_request(struct request_queue *, int, gfp_t);
 664 extern void blk_insert_request(struct request_queue *, struct request *, int, void *);
 665 extern void blk_requeue_request(struct request_queue *, struct request *);
 666 extern void blk_plug_device(struct request_queue *);
 667 extern int blk_remove_plug(struct request_queue *);
 668 extern void blk_recount_segments(struct request_queue *, struct bio *);
 669 extern int scsi_cmd_ioctl(struct file *, struct request_queue *,
 670                           struct gendisk *, unsigned int, void __user *);
 671 extern int sg_scsi_ioctl(struct file *, struct request_queue *,
 672                 struct gendisk *, struct scsi_ioctl_command __user *);
 673
 674 /*
 675  * Temporary export, until SCSI gets fixed up.
 676  */
 677 extern int blk_rq_append_bio(struct request_queue *q, struct request *rq,
 678                              struct bio *bio);
 679
 680 /*
 681  * A queue has just exitted congestion.  Note this in the global counter of
 682  * congested queues, and wake up anyone who was waiting for requests to be
 683  * put back.
 684  */
 685 static inline void blk_clear_queue_congested(struct request_queue *q, int rw)
 686 {
 687         clear_bdi_congested(&q->backing_dev_info, rw);
 688 }
 689
 690 /*
 691  * A queue has just entered congestion.  Flag that in the queue's VM-visible
 692  * state flags and increment the global gounter of congested queues.
 693  */
 694 static inline void blk_set_queue_congested(struct request_queue *q, int rw)
 695 {
 696         set_bdi_congested(&q->backing_dev_info, rw);
 697 }
 698
 699 extern void blk_start_queue(struct request_queue *q);
 700 extern void blk_stop_queue(struct request_queue *q);
 701 extern void blk_sync_queue(struct request_queue *q);
 702 extern void __blk_stop_queue(struct request_queue *q);
 703 extern void blk_run_queue(struct request_queue *);
 704 extern void blk_start_queueing(struct request_queue *);
 705 extern int blk_rq_map_user(struct request_queue *, struct request *, void __user *, unsigned long);
 706 extern int blk_rq_unmap_user(struct bio *);
 707 extern int blk_rq_map_kern(struct request_queue *, struct request *, void *, unsigned int, gfp_t);
 708 extern int blk_rq_map_user_iov(struct request_queue *, struct request *,
 709                                struct sg_iovec *, int, unsigned int);
 710 extern int blk_execute_rq(struct request_queue *, struct gendisk *,
 711                           struct request *, int);
 712 extern void blk_execute_rq_nowait(struct request_queue *, struct gendisk *,
 713                                   struct request *, int, rq_end_io_fn *);
 714 extern int blk_verify_command(unsigned char *, int);
 715
 716 static inline struct request_queue *bdev_get_queue(struct block_device *bdev)
 717 {
 718         return bdev->bd_disk->queue;
 719 }
 720
 721 static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
 722                                        struct page *page)
 723 {
 724         if (bdi && bdi->unplug_io_fn)
 725                 bdi->unplug_io_fn(bdi, page);
 726 }
 727
 728 static inline void blk_run_address_space(struct address_space *mapping)
 729 {
 730         if (mapping)
 731                 blk_run_backing_dev(mapping->backing_dev_info, NULL);
 732 }
 733
 734 /*
 735  * end_request() and friends. Must be called with the request queue spinlock
 736  * acquired. All functions called within end_request() _must_be_ atomic.
 737  *
 738  * Several drivers define their own end_request and call
 739  * end_that_request_first() and end_that_request_last()
 740  * for parts of the original function. This prevents
 741  * code duplication in drivers.
 742  */
 743 extern int end_that_request_first(struct request *, int, int);
 744 extern int end_that_request_chunk(struct request *, int, int);
 745 extern void end_that_request_last(struct request *, int);
 746 extern void end_request(struct request *req, int uptodate);
 747 extern void blk_complete_request(struct request *);
 748
 749 /*
 750  * end_that_request_first/chunk() takes an uptodate argument. we account
 751  * any value <= as an io error. 0 means -EIO for compatability reasons,
 752  * any other < 0 value is the direct error type. An uptodate value of
 753  * 1 indicates successful io completion
 754  */
 755 #define end_io_error(uptodate)  (unlikely((uptodate) <= 0))
 756
 757 static inline void blkdev_dequeue_request(struct request *req)
 758 {
 759         elv_dequeue_request(req->q, req);
 760 }
 761
 762 /*
 763  * Access functions for manipulating queue properties
 764  */
 765 extern struct request_queue *blk_init_queue_node(request_fn_proc *rfn,
 766                                         spinlock_t *lock, int node_id);
 767 extern struct request_queue *blk_init_queue(request_fn_proc *, spinlock_t *);
 768 extern void blk_cleanup_queue(struct request_queue *);
 769 extern void blk_queue_make_request(struct request_queue *, make_request_fn *);
 770 extern void blk_queue_bounce_limit(struct request_queue *, u64);
 771 extern void blk_queue_max_sectors(struct request_queue *, unsigned int);
 772 extern void blk_queue_max_phys_segments(struct request_queue *, unsigned short);
 773 extern void blk_queue_max_hw_segments(struct request_queue *, unsigned short);
 774 extern void blk_queue_max_segment_size(struct request_queue *, unsigned int);
 775 extern void blk_queue_hardsect_size(struct request_queue *, unsigned short);
 776 extern void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b);
 777 extern void blk_queue_segment_boundary(struct request_queue *, unsigned long);
 778 extern void blk_queue_prep_rq(struct request_queue *, prep_rq_fn *pfn);
 779 extern void blk_queue_merge_bvec(struct request_queue *, merge_bvec_fn *);
 780 extern void blk_queue_dma_alignment(struct request_queue *, int);
 781 extern void blk_queue_softirq_done(struct request_queue *, softirq_done_fn *);
 782 extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);
 783 extern int blk_queue_ordered(struct request_queue *, unsigned, prepare_flush_fn *);
 784 extern void blk_queue_issue_flush_fn(struct request_queue *, issue_flush_fn *);
 785 extern int blk_do_ordered(struct request_queue *, struct request **);
 786 extern unsigned blk_ordered_cur_seq(struct request_queue *);
 787 extern unsigned blk_ordered_req_seq(struct request *);
 788 extern void blk_ordered_complete_seq(struct request_queue *, unsigned, int);
 789
 790 extern int blk_rq_map_sg(struct request_queue *, struct request *, struct scatterlist *);
 791 extern void blk_dump_rq_flags(struct request *, char *);
 792 extern void generic_unplug_device(struct request_queue *);
 793 extern void __generic_unplug_device(struct request_queue *);
 794 extern long nr_blockdev_pages(void);
 795
 796 int blk_get_queue(struct request_queue *);
 797 struct request_queue *blk_alloc_queue(gfp_t);
 798 struct request_queue *blk_alloc_queue_node(gfp_t, int);
 799 extern void blk_put_queue(struct request_queue *);
 800
 801 /*
 802  * tag stuff
 803  */
 804 #define blk_queue_tag_depth(q)          ((q)->queue_tags->busy)
 805 #define blk_queue_tag_queue(q)          ((q)->queue_tags->busy < (q)->queue_tags->max_depth)
 806 #define blk_rq_tagged(rq)               ((rq)->cmd_flags & REQ_QUEUED)
 807 extern int blk_queue_start_tag(struct request_queue *, struct request *);
 808 extern struct request *blk_queue_find_tag(struct request_queue *, int);
 809 extern void blk_queue_end_tag(struct request_queue *, struct request *);
 810 extern int blk_queue_init_tags(struct request_queue *, int, struct blk_queue_tag *);
 811 extern void blk_queue_free_tags(struct request_queue *);
 812 extern int blk_queue_resize_tags(struct request_queue *, int);
 813 extern void blk_queue_invalidate_tags(struct request_queue *);
 814 extern struct blk_queue_tag *blk_init_tags(int);
 815 extern void blk_free_tags(struct blk_queue_tag *);
 816
 817 static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
 818                                                 int tag)
 819 {
 820         if (unlikely(bqt == NULL || tag >= bqt->real_max_depth))
 821                 return NULL;
 822         return bqt->tag_index[tag];
 823 }
 824
 825 extern int blkdev_issue_flush(struct block_device *, sector_t *);
 826
 827 #define MAX_PHYS_SEGMENTS 128
 828 #define MAX_HW_SEGMENTS 128
 829 #define SAFE_MAX_SECTORS 255
 830 #define BLK_DEF_MAX_SECTORS 1024
 831
 832 #define MAX_SEGMENT_SIZE        65536
 833
 834 #define blkdev_entry_to_request(entry) list_entry((entry), struct request, queuelist)
 835
 836 static inline int queue_hardsect_size(struct request_queue *q)
 837 {
 838         int retval = 512;
 839
 840         if (q && q->hardsect_size)
 841                 retval = q->hardsect_size;
 842
 843         return retval;
 844 }
 845
 846 static inline int bdev_hardsect_size(struct block_device *bdev)
 847 {
 848         return queue_hardsect_size(bdev_get_queue(bdev));
 849 }
 850
 851 static inline int queue_dma_alignment(struct request_queue *q)
 852 {
 853         int retval = 511;
 854
 855         if (q && q->dma_alignment)
 856                 retval = q->dma_alignment;
 857
 858         return retval;
 859 }
 860
 861 /* assumes size > 256 */
 862 static inline unsigned int blksize_bits(unsigned int size)
 863 {
 864         unsigned int bits = 8;
 865         do {
 866                 bits++;
 867                 size >>= 1;
 868         } while (size > 256);
 869         return bits;
 870 }
 871
 872 static inline unsigned int block_size(struct block_device *bdev)
 873 {
 874         return bdev->bd_block_size;
 875 }
 876
 877 typedef struct {struct page *v;} Sector;
 878
 879 unsigned char *read_dev_sector(struct block_device *, sector_t, Sector *);
 880
 881 static inline void put_dev_sector(Sector p)
 882 {
 883         page_cache_release(p.v);
 884 }
 885
 886 struct work_struct;
 887 int kblockd_schedule_work(struct work_struct *work);
 888 void kblockd_flush_work(struct work_struct *work);
 889
 890 #define MODULE_ALIAS_BLOCKDEV(major,minor) \
 891         MODULE_ALIAS("block-major-" __stringify(major) "-" __stringify(minor))
 892 #define MODULE_ALIAS_BLOCKDEV_MAJOR(major) \
 893         MODULE_ALIAS("block-major-" __stringify(major) "-*")
 894
 895
 896 #else /* CONFIG_BLOCK */
 897 /*
 898  * stubs for when the block layer is configured out
 899  */
 900 #define buffer_heads_over_limit 0
 901
 902 static inline long nr_blockdev_pages(void)
 903 {
 904         return 0;
 905 }
 906
 907 static inline void exit_io_context(void)
 908 {
 909 }
 910
 911 #endif /* CONFIG_BLOCK */
 912
 913 #endif