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/gfp.h>
  20 #include <linux/bsg.h>
  21 #include <linux/smp.h>
  22
  23 #include <asm/scatterlist.h>
  24
  25 struct scsi_ioctl_command;
  26
  27 struct request_queue;
  28 struct elevator_queue;
  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 struct request;
  38 typedef void (rq_end_io_fn)(struct request *, int);
  39
  40 struct request_list {
  41         /*
  42          * count[], starved[], and wait[] are indexed by
  43          * BLK_RW_SYNC/BLK_RW_ASYNC
  44          */
  45         int count[2];
  46         int starved[2];
  47         int elvpriv;
  48         mempool_t *rq_pool;
  49         wait_queue_head_t wait[2];
  50 };
  51
  52 /*
  53  * request command types
  54  */
  55 enum rq_cmd_type_bits {
  56         REQ_TYPE_FS             = 1,    /* fs request */
  57         REQ_TYPE_BLOCK_PC,              /* scsi command */
  58         REQ_TYPE_SENSE,                 /* sense request */
  59         REQ_TYPE_PM_SUSPEND,            /* suspend request */
  60         REQ_TYPE_PM_RESUME,             /* resume request */
  61         REQ_TYPE_PM_SHUTDOWN,           /* shutdown request */
  62         REQ_TYPE_SPECIAL,               /* driver defined type */
  63         REQ_TYPE_LINUX_BLOCK,           /* generic block layer message */
  64         /*
  65          * for ATA/ATAPI devices. this really doesn't belong here, ide should
  66          * use REQ_TYPE_SPECIAL and use rq->cmd[0] with the range of driver
  67          * private REQ_LB opcodes to differentiate what type of request this is
  68          */
  69         REQ_TYPE_ATA_TASKFILE,
  70         REQ_TYPE_ATA_PC,
  71 };
  72
  73 enum {
  74         BLK_RW_ASYNC    = 0,
  75         BLK_RW_SYNC     = 1,
  76 };
  77
  78 /*
  79  * For request of type REQ_TYPE_LINUX_BLOCK, rq->cmd[0] is the opcode being
  80  * sent down (similar to how REQ_TYPE_BLOCK_PC means that ->cmd[] holds a
  81  * SCSI cdb.
  82  *
  83  * 0x00 -> 0x3f are driver private, to be used for whatever purpose they need,
  84  * typically to differentiate REQ_TYPE_SPECIAL requests.
  85  *
  86  */
  87 enum {
  88         REQ_LB_OP_EJECT = 0x40,         /* eject request */
  89         REQ_LB_OP_FLUSH = 0x41,         /* flush request */
  90         REQ_LB_OP_DISCARD = 0x42,       /* discard sectors */
  91 };
  92
  93 /*
  94  * request type modified bits. first two bits match BIO_RW* bits, important
  95  */
  96 enum rq_flag_bits {
  97         __REQ_RW,               /* not set, read. set, write */
  98         __REQ_FAILFAST_DEV,     /* no driver retries of device errors */
  99         __REQ_FAILFAST_TRANSPORT, /* no driver retries of transport errors */
 100         __REQ_FAILFAST_DRIVER,  /* no driver retries of driver errors */
 101         __REQ_DISCARD,          /* request to discard sectors */
 102         __REQ_SORTED,           /* elevator knows about this request */
 103         __REQ_SOFTBARRIER,      /* may not be passed by ioscheduler */
 104         __REQ_HARDBARRIER,      /* may not be passed by drive either */
 105         __REQ_FUA,              /* forced unit access */
 106         __REQ_NOMERGE,          /* don't touch this for merging */
 107         __REQ_STARTED,          /* drive already may have started this one */
 108         __REQ_DONTPREP,         /* don't call prep for this one */
 109         __REQ_QUEUED,           /* uses queueing */
 110         __REQ_ELVPRIV,          /* elevator private data attached */
 111         __REQ_FAILED,           /* set if the request failed */
 112         __REQ_QUIET,            /* don't worry about errors */
 113         __REQ_PREEMPT,          /* set for "ide_preempt" requests */
 114         __REQ_ORDERED_COLOR,    /* is before or after barrier */
 115         __REQ_RW_SYNC,          /* request is sync (sync write or read) */
 116         __REQ_ALLOCED,          /* request came from our alloc pool */
 117         __REQ_RW_META,          /* metadata io request */
 118         __REQ_COPY_USER,        /* contains copies of user pages */
 119         __REQ_INTEGRITY,        /* integrity metadata has been remapped */
 120         __REQ_NOIDLE,           /* Don't anticipate more IO after this one */
 121         __REQ_NR_BITS,          /* stops here */
 122 };
 123
 124 #define REQ_RW          (1 << __REQ_RW)
 125 #define REQ_FAILFAST_DEV        (1 << __REQ_FAILFAST_DEV)
 126 #define REQ_FAILFAST_TRANSPORT  (1 << __REQ_FAILFAST_TRANSPORT)
 127 #define REQ_FAILFAST_DRIVER     (1 << __REQ_FAILFAST_DRIVER)
 128 #define REQ_DISCARD     (1 << __REQ_DISCARD)
 129 #define REQ_SORTED      (1 << __REQ_SORTED)
 130 #define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER)
 131 #define REQ_HARDBARRIER (1 << __REQ_HARDBARRIER)
 132 #define REQ_FUA         (1 << __REQ_FUA)
 133 #define REQ_NOMERGE     (1 << __REQ_NOMERGE)
 134 #define REQ_STARTED     (1 << __REQ_STARTED)
 135 #define REQ_DONTPREP    (1 << __REQ_DONTPREP)
 136 #define REQ_QUEUED      (1 << __REQ_QUEUED)
 137 #define REQ_ELVPRIV     (1 << __REQ_ELVPRIV)
 138 #define REQ_FAILED      (1 << __REQ_FAILED)
 139 #define REQ_QUIET       (1 << __REQ_QUIET)
 140 #define REQ_PREEMPT     (1 << __REQ_PREEMPT)
 141 #define REQ_ORDERED_COLOR       (1 << __REQ_ORDERED_COLOR)
 142 #define REQ_RW_SYNC     (1 << __REQ_RW_SYNC)
 143 #define REQ_ALLOCED     (1 << __REQ_ALLOCED)
 144 #define REQ_RW_META     (1 << __REQ_RW_META)
 145 #define REQ_COPY_USER   (1 << __REQ_COPY_USER)
 146 #define REQ_INTEGRITY   (1 << __REQ_INTEGRITY)
 147 #define REQ_NOIDLE      (1 << __REQ_NOIDLE)
 148
 149 #define BLK_MAX_CDB     16
 150
 151 /*
 152  * try to put the fields that are referenced together in the same cacheline.
 153  * if you modify this structure, be sure to check block/blk-core.c:rq_init()
 154  * as well!
 155  */
 156 struct request {
 157         struct list_head queuelist;
 158         struct call_single_data csd;
 159         int cpu;
 160
 161         struct request_queue *q;
 162
 163         unsigned int cmd_flags;
 164         enum rq_cmd_type_bits cmd_type;
 165         unsigned long atomic_flags;
 166
 167         /* Maintain bio traversal state for part by part I/O submission.
 168          * hard_* are block layer internals, no driver should touch them!
 169          */
 170
 171         sector_t sector;                /* next sector to submit */
 172         sector_t hard_sector;           /* next sector to complete */
 173         unsigned long nr_sectors;       /* no. of sectors left to submit */
 174         unsigned long hard_nr_sectors;  /* no. of sectors left to complete */
 175         /* no. of sectors left to submit in the current segment */
 176         unsigned int current_nr_sectors;
 177
 178         /* no. of sectors left to complete in the current segment */
 179         unsigned int hard_cur_sectors;
 180
 181         struct bio *bio;
 182         struct bio *biotail;
 183
 184         struct hlist_node hash; /* merge hash */
 185         /*
 186          * The rb_node is only used inside the io scheduler, requests
 187          * are pruned when moved to the dispatch queue. So let the
 188          * completion_data share space with the rb_node.
 189          */
 190         union {
 191                 struct rb_node rb_node; /* sort/lookup */
 192                 void *completion_data;
 193         };
 194
 195         /*
 196          * two pointers are available for the IO schedulers, if they need
 197          * more they have to dynamically allocate it.
 198          */
 199         void *elevator_private;
 200         void *elevator_private2;
 201
 202         struct gendisk *rq_disk;
 203         unsigned long start_time;
 204
 205         /* Number of scatter-gather DMA addr+len pairs after
 206          * physical address coalescing is performed.
 207          */
 208         unsigned short nr_phys_segments;
 209
 210         unsigned short ioprio;
 211
 212         void *special;
 213         char *buffer;
 214
 215         int tag;
 216         int errors;
 217
 218         int ref_count;
 219
 220         /*
 221          * when request is used as a packet command carrier
 222          */
 223         unsigned short cmd_len;
 224         unsigned char __cmd[BLK_MAX_CDB];
 225         unsigned char *cmd;
 226
 227         unsigned int data_len;
 228         unsigned int extra_len; /* length of alignment and padding */
 229         unsigned int sense_len;
 230         void *data;
 231         void *sense;
 232
 233         unsigned long deadline;
 234         struct list_head timeout_list;
 235         unsigned int timeout;
 236         int retries;
 237
 238         /*
 239          * completion callback.
 240          */
 241         rq_end_io_fn *end_io;
 242         void *end_io_data;
 243
 244         /* for bidi */
 245         struct request *next_rq;
 246 };
 247
 248 static inline unsigned short req_get_ioprio(struct request *req)
 249 {
 250         return req->ioprio;
 251 }
 252
 253 /*
 254  * State information carried for REQ_TYPE_PM_SUSPEND and REQ_TYPE_PM_RESUME
 255  * requests. Some step values could eventually be made generic.
 256  */
 257 struct request_pm_state
 258 {
 259         /* PM state machine step value, currently driver specific */
 260         int     pm_step;
 261         /* requested PM state value (S1, S2, S3, S4, ...) */
 262         u32     pm_state;
 263         void*   data;           /* for driver use */
 264 };
 265
 266 #include <linux/elevator.h>
 267
 268 typedef void (request_fn_proc) (struct request_queue *q);
 269 typedef int (make_request_fn) (struct request_queue *q, struct bio *bio);
 270 typedef int (prep_rq_fn) (struct request_queue *, struct request *);
 271 typedef void (unplug_fn) (struct request_queue *);
 272 typedef int (prepare_discard_fn) (struct request_queue *, struct request *);
 273
 274 struct bio_vec;
 275 struct bvec_merge_data {
 276         struct block_device *bi_bdev;
 277         sector_t bi_sector;
 278         unsigned bi_size;
 279         unsigned long bi_rw;
 280 };
 281 typedef int (merge_bvec_fn) (struct request_queue *, struct bvec_merge_data *,
 282                              struct bio_vec *);
 283 typedef void (prepare_flush_fn) (struct request_queue *, struct request *);
 284 typedef void (softirq_done_fn)(struct request *);
 285 typedef int (dma_drain_needed_fn)(struct request *);
 286 typedef int (lld_busy_fn) (struct request_queue *q);
 287
 288 enum blk_eh_timer_return {
 289         BLK_EH_NOT_HANDLED,
 290         BLK_EH_HANDLED,
 291         BLK_EH_RESET_TIMER,
 292 };
 293
 294 typedef enum blk_eh_timer_return (rq_timed_out_fn)(struct request *);
 295
 296 enum blk_queue_state {
 297         Queue_down,
 298         Queue_up,
 299 };
 300
 301 struct blk_queue_tag {
 302         struct request **tag_index;     /* map of busy tags */
 303         unsigned long *tag_map;         /* bit map of free/busy tags */
 304         int busy;                       /* current depth */
 305         int max_depth;                  /* what we will send to device */
 306         int real_max_depth;             /* what the array can hold */
 307         atomic_t refcnt;                /* map can be shared */
 308 };
 309
 310 #define BLK_SCSI_MAX_CMDS       (256)
 311 #define BLK_SCSI_CMD_PER_LONG   (BLK_SCSI_MAX_CMDS / (sizeof(long) * 8))
 312
 313 struct blk_cmd_filter {
 314         unsigned long read_ok[BLK_SCSI_CMD_PER_LONG];
 315         unsigned long write_ok[BLK_SCSI_CMD_PER_LONG];
 316         struct kobject kobj;
 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         struct elevator_queue   *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         make_request_fn         *make_request_fn;
 335         prep_rq_fn              *prep_rq_fn;
 336         unplug_fn               *unplug_fn;
 337         prepare_discard_fn      *prepare_discard_fn;
 338         merge_bvec_fn           *merge_bvec_fn;
 339         prepare_flush_fn        *prepare_flush_fn;
 340         softirq_done_fn         *softirq_done_fn;
 341         rq_timed_out_fn         *rq_timed_out_fn;
 342         dma_drain_needed_fn     *dma_drain_needed;
 343         lld_busy_fn             *lld_busy_fn;
 344
 345         /*
 346          * Dispatch queue sorting
 347          */
 348         sector_t                end_sector;
 349         struct request          *boundary_rq;
 350
 351         /*
 352          * Auto-unplugging state
 353          */
 354         struct timer_list       unplug_timer;
 355         int                     unplug_thresh;  /* After this many requests */
 356         unsigned long           unplug_delay;   /* After this many jiffies */
 357         struct work_struct      unplug_work;
 358
 359         struct backing_dev_info backing_dev_info;
 360
 361         /*
 362          * The queue owner gets to use this for whatever they like.
 363          * ll_rw_blk doesn't touch it.
 364          */
 365         void                    *queuedata;
 366
 367         /*
 368          * queue needs bounce pages for pages above this limit
 369          */
 370         unsigned long           bounce_pfn;
 371         gfp_t                   bounce_gfp;
 372
 373         /*
 374          * various queue flags, see QUEUE_* below
 375          */
 376         unsigned long           queue_flags;
 377
 378         /*
 379          * protects queue structures from reentrancy. ->__queue_lock should
 380          * _never_ be used directly, it is queue private. always use
 381          * ->queue_lock.
 382          */
 383         spinlock_t              __queue_lock;
 384         spinlock_t              *queue_lock;
 385
 386         /*
 387          * queue kobject
 388          */
 389         struct kobject kobj;
 390
 391         /*
 392          * queue settings
 393          */
 394         unsigned long           nr_requests;    /* Max # of requests */
 395         unsigned int            nr_congestion_on;
 396         unsigned int            nr_congestion_off;
 397         unsigned int            nr_batching;
 398
 399         unsigned int            max_sectors;
 400         unsigned int            max_hw_sectors;
 401         unsigned short          max_phys_segments;
 402         unsigned short          max_hw_segments;
 403         unsigned short          hardsect_size;
 404         unsigned int            max_segment_size;
 405
 406         unsigned long           seg_boundary_mask;
 407         void                    *dma_drain_buffer;
 408         unsigned int            dma_drain_size;
 409         unsigned int            dma_pad_mask;
 410         unsigned int            dma_alignment;
 411
 412         struct blk_queue_tag    *queue_tags;
 413         struct list_head        tag_busy_list;
 414
 415         unsigned int            nr_sorted;
 416         unsigned int            in_flight;
 417
 418         unsigned int            rq_timeout;
 419         struct timer_list       timeout;
 420         struct list_head        timeout_list;
 421
 422         /*
 423          * sg stuff
 424          */
 425         unsigned int            sg_timeout;
 426         unsigned int            sg_reserved_size;
 427         int                     node;
 428 #ifdef CONFIG_BLK_DEV_IO_TRACE
 429         struct blk_trace        *blk_trace;
 430 #endif
 431         /*
 432          * reserved for flush operations
 433          */
 434         unsigned int            ordered, next_ordered, ordseq;
 435         int                     orderr, ordcolor;
 436         struct request          pre_flush_rq, bar_rq, post_flush_rq;
 437         struct request          *orig_bar_rq;
 438
 439         struct mutex            sysfs_lock;
 440
 441 #if defined(CONFIG_BLK_DEV_BSG)
 442         struct bsg_class_device bsg_dev;
 443 #endif
 444         struct blk_cmd_filter cmd_filter;
 445 };
 446
 447 #define QUEUE_FLAG_CLUSTER      0       /* cluster several segments into 1 */
 448 #define QUEUE_FLAG_QUEUED       1       /* uses generic tag queueing */
 449 #define QUEUE_FLAG_STOPPED      2       /* queue is stopped */
 450 #define QUEUE_FLAG_SYNCFULL     3       /* read queue has been filled */
 451 #define QUEUE_FLAG_ASYNCFULL    4       /* write queue has been filled */
 452 #define QUEUE_FLAG_DEAD         5       /* queue being torn down */
 453 #define QUEUE_FLAG_REENTER      6       /* Re-entrancy avoidance */
 454 #define QUEUE_FLAG_PLUGGED      7       /* queue is plugged */
 455 #define QUEUE_FLAG_ELVSWITCH    8       /* don't use elevator, just do FIFO */
 456 #define QUEUE_FLAG_BIDI         9       /* queue supports bidi requests */
 457 #define QUEUE_FLAG_NOMERGES    10       /* disable merge attempts */
 458 #define QUEUE_FLAG_SAME_COMP   11       /* force complete on same CPU */
 459 #define QUEUE_FLAG_FAIL_IO     12       /* fake timeout */
 460 #define QUEUE_FLAG_STACKABLE   13       /* supports request stacking */
 461 #define QUEUE_FLAG_NONROT      14       /* non-rotational device (SSD) */
 462 #define QUEUE_FLAG_VIRT        QUEUE_FLAG_NONROT /* paravirt device */
 463 #define QUEUE_FLAG_IO_STAT     15       /* do IO stats */
 464
 465 #define QUEUE_FLAG_DEFAULT      ((1 << QUEUE_FLAG_IO_STAT) |            \
 466                                  (1 << QUEUE_FLAG_CLUSTER) |            \
 467                                  (1 << QUEUE_FLAG_STACKABLE))
 468
 469 static inline int queue_is_locked(struct request_queue *q)
 470 {
 471 #ifdef CONFIG_SMP
 472         spinlock_t *lock = q->queue_lock;
 473         return lock && spin_is_locked(lock);
 474 #else
 475         return 1;
 476 #endif
 477 }
 478
 479 static inline void queue_flag_set_unlocked(unsigned int flag,
 480                                            struct request_queue *q)
 481 {
 482         __set_bit(flag, &q->queue_flags);
 483 }
 484
 485 static inline int queue_flag_test_and_clear(unsigned int flag,
 486                                             struct request_queue *q)
 487 {
 488         WARN_ON_ONCE(!queue_is_locked(q));
 489
 490         if (test_bit(flag, &q->queue_flags)) {
 491                 __clear_bit(flag, &q->queue_flags);
 492                 return 1;
 493         }
 494
 495         return 0;
 496 }
 497
 498 static inline int queue_flag_test_and_set(unsigned int flag,
 499                                           struct request_queue *q)
 500 {
 501         WARN_ON_ONCE(!queue_is_locked(q));
 502
 503         if (!test_bit(flag, &q->queue_flags)) {
 504                 __set_bit(flag, &q->queue_flags);
 505                 return 0;
 506         }
 507
 508         return 1;
 509 }
 510
 511 static inline void queue_flag_set(unsigned int flag, struct request_queue *q)
 512 {
 513         WARN_ON_ONCE(!queue_is_locked(q));
 514         __set_bit(flag, &q->queue_flags);
 515 }
 516
 517 static inline void queue_flag_clear_unlocked(unsigned int flag,
 518                                              struct request_queue *q)
 519 {
 520         __clear_bit(flag, &q->queue_flags);
 521 }
 522
 523 static inline void queue_flag_clear(unsigned int flag, struct request_queue *q)
 524 {
 525         WARN_ON_ONCE(!queue_is_locked(q));
 526         __clear_bit(flag, &q->queue_flags);
 527 }
 528
 529 enum {
 530         /*
 531          * Hardbarrier is supported with one of the following methods.
 532          *
 533          * NONE         : hardbarrier unsupported
 534          * DRAIN        : ordering by draining is enough
 535          * DRAIN_FLUSH  : ordering by draining w/ pre and post flushes
 536          * DRAIN_FUA    : ordering by draining w/ pre flush and FUA write
 537          * TAG          : ordering by tag is enough
 538          * TAG_FLUSH    : ordering by tag w/ pre and post flushes
 539          * TAG_FUA      : ordering by tag w/ pre flush and FUA write
 540          */
 541         QUEUE_ORDERED_BY_DRAIN          = 0x01,
 542         QUEUE_ORDERED_BY_TAG            = 0x02,
 543         QUEUE_ORDERED_DO_PREFLUSH       = 0x10,
 544         QUEUE_ORDERED_DO_BAR            = 0x20,
 545         QUEUE_ORDERED_DO_POSTFLUSH      = 0x40,
 546         QUEUE_ORDERED_DO_FUA            = 0x80,
 547
 548         QUEUE_ORDERED_NONE              = 0x00,
 549
 550         QUEUE_ORDERED_DRAIN             = QUEUE_ORDERED_BY_DRAIN |
 551                                           QUEUE_ORDERED_DO_BAR,
 552         QUEUE_ORDERED_DRAIN_FLUSH       = QUEUE_ORDERED_DRAIN |
 553                                           QUEUE_ORDERED_DO_PREFLUSH |
 554                                           QUEUE_ORDERED_DO_POSTFLUSH,
 555         QUEUE_ORDERED_DRAIN_FUA         = QUEUE_ORDERED_DRAIN |
 556                                           QUEUE_ORDERED_DO_PREFLUSH |
 557                                           QUEUE_ORDERED_DO_FUA,
 558
 559         QUEUE_ORDERED_TAG               = QUEUE_ORDERED_BY_TAG |
 560                                           QUEUE_ORDERED_DO_BAR,
 561         QUEUE_ORDERED_TAG_FLUSH         = QUEUE_ORDERED_TAG |
 562                                           QUEUE_ORDERED_DO_PREFLUSH |
 563                                           QUEUE_ORDERED_DO_POSTFLUSH,
 564         QUEUE_ORDERED_TAG_FUA           = QUEUE_ORDERED_TAG |
 565                                           QUEUE_ORDERED_DO_PREFLUSH |
 566                                           QUEUE_ORDERED_DO_FUA,
 567
 568         /*
 569          * Ordered operation sequence
 570          */
 571         QUEUE_ORDSEQ_STARTED    = 0x01, /* flushing in progress */
 572         QUEUE_ORDSEQ_DRAIN      = 0x02, /* waiting for the queue to be drained */
 573         QUEUE_ORDSEQ_PREFLUSH   = 0x04, /* pre-flushing in progress */
 574         QUEUE_ORDSEQ_BAR        = 0x08, /* original barrier req in progress */
 575         QUEUE_ORDSEQ_POSTFLUSH  = 0x10, /* post-flushing in progress */
 576         QUEUE_ORDSEQ_DONE       = 0x20,
 577 };
 578
 579 #define blk_queue_plugged(q)    test_bit(QUEUE_FLAG_PLUGGED, &(q)->queue_flags)
 580 #define blk_queue_tagged(q)     test_bit(QUEUE_FLAG_QUEUED, &(q)->queue_flags)
 581 #define blk_queue_stopped(q)    test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
 582 #define blk_queue_nomerges(q)   test_bit(QUEUE_FLAG_NOMERGES, &(q)->queue_flags)
 583 #define blk_queue_nonrot(q)     test_bit(QUEUE_FLAG_NONROT, &(q)->queue_flags)
 584 #define blk_queue_io_stat(q)    test_bit(QUEUE_FLAG_IO_STAT, &(q)->queue_flags)
 585 #define blk_queue_flushing(q)   ((q)->ordseq)
 586 #define blk_queue_stackable(q)  \
 587         test_bit(QUEUE_FLAG_STACKABLE, &(q)->queue_flags)
 588
 589 #define blk_fs_request(rq)      ((rq)->cmd_type == REQ_TYPE_FS)
 590 #define blk_pc_request(rq)      ((rq)->cmd_type == REQ_TYPE_BLOCK_PC)
 591 #define blk_special_request(rq) ((rq)->cmd_type == REQ_TYPE_SPECIAL)
 592 #define blk_sense_request(rq)   ((rq)->cmd_type == REQ_TYPE_SENSE)
 593
 594 #define blk_failfast_dev(rq)    ((rq)->cmd_flags & REQ_FAILFAST_DEV)
 595 #define blk_failfast_transport(rq) ((rq)->cmd_flags & REQ_FAILFAST_TRANSPORT)
 596 #define blk_failfast_driver(rq) ((rq)->cmd_flags & REQ_FAILFAST_DRIVER)
 597 #define blk_noretry_request(rq) (blk_failfast_dev(rq) ||        \
 598                                  blk_failfast_transport(rq) ||  \
 599                                  blk_failfast_driver(rq))
 600 #define blk_rq_started(rq)      ((rq)->cmd_flags & REQ_STARTED)
 601
 602 #define blk_account_rq(rq)      (blk_rq_started(rq) && (blk_fs_request(rq) || blk_discard_rq(rq)))
 603
 604 #define blk_pm_suspend_request(rq)      ((rq)->cmd_type == REQ_TYPE_PM_SUSPEND)
 605 #define blk_pm_resume_request(rq)       ((rq)->cmd_type == REQ_TYPE_PM_RESUME)
 606 #define blk_pm_request(rq)      \
 607         (blk_pm_suspend_request(rq) || blk_pm_resume_request(rq))
 608
 609 #define blk_rq_cpu_valid(rq)    ((rq)->cpu != -1)
 610 #define blk_sorted_rq(rq)       ((rq)->cmd_flags & REQ_SORTED)
 611 #define blk_barrier_rq(rq)      ((rq)->cmd_flags & REQ_HARDBARRIER)
 612 #define blk_fua_rq(rq)          ((rq)->cmd_flags & REQ_FUA)
 613 #define blk_discard_rq(rq)      ((rq)->cmd_flags & REQ_DISCARD)
 614 #define blk_bidi_rq(rq)         ((rq)->next_rq != NULL)
 615 /* rq->queuelist of dequeued request must be list_empty() */
 616 #define blk_queued_rq(rq)       (!list_empty(&(rq)->queuelist))
 617
 618 #define list_entry_rq(ptr)      list_entry((ptr), struct request, queuelist)
 619
 620 #define rq_data_dir(rq)         ((rq)->cmd_flags & 1)
 621
 622 /*
 623  * We regard a request as sync, if either a read or a sync write
 624  */
 625 static inline bool rw_is_sync(unsigned int rw_flags)
 626 {
 627         return !(rw_flags & REQ_RW) || (rw_flags & REQ_RW_SYNC);
 628 }
 629
 630 static inline bool rq_is_sync(struct request *rq)
 631 {
 632         return rw_is_sync(rq->cmd_flags);
 633 }
 634
 635 #define rq_is_meta(rq)          ((rq)->cmd_flags & REQ_RW_META)
 636 #define rq_noidle(rq)           ((rq)->cmd_flags & REQ_NOIDLE)
 637
 638 static inline int blk_queue_full(struct request_queue *q, int sync)
 639 {
 640         if (sync)
 641                 return test_bit(QUEUE_FLAG_SYNCFULL, &q->queue_flags);
 642         return test_bit(QUEUE_FLAG_ASYNCFULL, &q->queue_flags);
 643 }
 644
 645 static inline void blk_set_queue_full(struct request_queue *q, int sync)
 646 {
 647         if (sync)
 648                 queue_flag_set(QUEUE_FLAG_SYNCFULL, q);
 649         else
 650                 queue_flag_set(QUEUE_FLAG_ASYNCFULL, q);
 651 }
 652
 653 static inline void blk_clear_queue_full(struct request_queue *q, int sync)
 654 {
 655         if (sync)
 656                 queue_flag_clear(QUEUE_FLAG_SYNCFULL, q);
 657         else
 658                 queue_flag_clear(QUEUE_FLAG_ASYNCFULL, q);
 659 }
 660
 661
 662 /*
 663  * mergeable request must not have _NOMERGE or _BARRIER bit set, nor may
 664  * it already be started by driver.
 665  */
 666 #define RQ_NOMERGE_FLAGS        \
 667         (REQ_NOMERGE | REQ_STARTED | REQ_HARDBARRIER | REQ_SOFTBARRIER)
 668 #define rq_mergeable(rq)        \
 669         (!((rq)->cmd_flags & RQ_NOMERGE_FLAGS) && \
 670          (blk_discard_rq(rq) || blk_fs_request((rq))))
 671
 672 /*
 673  * q->prep_rq_fn return values
 674  */
 675 #define BLKPREP_OK              0       /* serve it */
 676 #define BLKPREP_KILL            1       /* fatal error, kill */
 677 #define BLKPREP_DEFER           2       /* leave on queue */
 678
 679 extern unsigned long blk_max_low_pfn, blk_max_pfn;
 680
 681 /*
 682  * standard bounce addresses:
 683  *
 684  * BLK_BOUNCE_HIGH      : bounce all highmem pages
 685  * BLK_BOUNCE_ANY       : don't bounce anything
 686  * BLK_BOUNCE_ISA       : bounce pages above ISA DMA boundary
 687  */
 688
 689 #if BITS_PER_LONG == 32
 690 #define BLK_BOUNCE_HIGH         ((u64)blk_max_low_pfn << PAGE_SHIFT)
 691 #else
 692 #define BLK_BOUNCE_HIGH         -1ULL
 693 #endif
 694 #define BLK_BOUNCE_ANY          (-1ULL)
 695 #define BLK_BOUNCE_ISA          (ISA_DMA_THRESHOLD)
 696
 697 /*
 698  * default timeout for SG_IO if none specified
 699  */
 700 #define BLK_DEFAULT_SG_TIMEOUT  (60 * HZ)
 701 #define BLK_MIN_SG_TIMEOUT      (7 * HZ)
 702
 703 #ifdef CONFIG_BOUNCE
 704 extern int init_emergency_isa_pool(void);
 705 extern void blk_queue_bounce(struct request_queue *q, struct bio **bio);
 706 #else
 707 static inline int init_emergency_isa_pool(void)
 708 {
 709         return 0;
 710 }
 711 static inline void blk_queue_bounce(struct request_queue *q, struct bio **bio)
 712 {
 713 }
 714 #endif /* CONFIG_MMU */
 715
 716 struct rq_map_data {
 717         struct page **pages;
 718         int page_order;
 719         int nr_entries;
 720         unsigned long offset;
 721         int null_mapped;
 722 };
 723
 724 struct req_iterator {
 725         int i;
 726         struct bio *bio;
 727 };
 728
 729 /* This should not be used directly - use rq_for_each_segment */
 730 #define for_each_bio(_bio)              \
 731         for (; _bio; _bio = _bio->bi_next)
 732 #define __rq_for_each_bio(_bio, rq)     \
 733         if ((rq->bio))                  \
 734                 for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)
 735
 736 #define rq_for_each_segment(bvl, _rq, _iter)                    \
 737         __rq_for_each_bio(_iter.bio, _rq)                       \
 738                 bio_for_each_segment(bvl, _iter.bio, _iter.i)
 739
 740 #define rq_iter_last(rq, _iter)                                 \
 741                 (_iter.bio->bi_next == NULL && _iter.i == _iter.bio->bi_vcnt-1)
 742
 743 extern int blk_register_queue(struct gendisk *disk);
 744 extern void blk_unregister_queue(struct gendisk *disk);
 745 extern void register_disk(struct gendisk *dev);
 746 extern void generic_make_request(struct bio *bio);
 747 extern void blk_rq_init(struct request_queue *q, struct request *rq);
 748 extern void blk_put_request(struct request *);
 749 extern void __blk_put_request(struct request_queue *, struct request *);
 750 extern struct request *blk_get_request(struct request_queue *, int, gfp_t);
 751 extern void blk_insert_request(struct request_queue *, struct request *, int, void *);
 752 extern void blk_requeue_request(struct request_queue *, struct request *);
 753 extern int blk_rq_check_limits(struct request_queue *q, struct request *rq);
 754 extern int blk_lld_busy(struct request_queue *q);
 755 extern int blk_insert_cloned_request(struct request_queue *q,
 756                                      struct request *rq);
 757 extern void blk_plug_device(struct request_queue *);
 758 extern void blk_plug_device_unlocked(struct request_queue *);
 759 extern int blk_remove_plug(struct request_queue *);
 760 extern void blk_recount_segments(struct request_queue *, struct bio *);
 761 extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t,
 762                           unsigned int, void __user *);
 763 extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t,
 764                          struct scsi_ioctl_command __user *);
 765
 766 /*
 767  * Temporary export, until SCSI gets fixed up.
 768  */
 769 extern int blk_rq_append_bio(struct request_queue *q, struct request *rq,
 770                              struct bio *bio);
 771
 772 /*
 773  * A queue has just exitted congestion.  Note this in the global counter of
 774  * congested queues, and wake up anyone who was waiting for requests to be
 775  * put back.
 776  */
 777 static inline void blk_clear_queue_congested(struct request_queue *q, int rw)
 778 {
 779         clear_bdi_congested(&q->backing_dev_info, rw);
 780 }
 781
 782 /*
 783  * A queue has just entered congestion.  Flag that in the queue's VM-visible
 784  * state flags and increment the global gounter of congested queues.
 785  */
 786 static inline void blk_set_queue_congested(struct request_queue *q, int rw)
 787 {
 788         set_bdi_congested(&q->backing_dev_info, rw);
 789 }
 790
 791 extern void blk_start_queue(struct request_queue *q);
 792 extern void blk_stop_queue(struct request_queue *q);
 793 extern void blk_sync_queue(struct request_queue *q);
 794 extern void __blk_stop_queue(struct request_queue *q);
 795 extern void __blk_run_queue(struct request_queue *);
 796 extern void blk_run_queue(struct request_queue *);
 797 extern void blk_start_queueing(struct request_queue *);
 798 extern int blk_rq_map_user(struct request_queue *, struct request *,
 799                            struct rq_map_data *, void __user *, unsigned long,
 800                            gfp_t);
 801 extern int blk_rq_unmap_user(struct bio *);
 802 extern int blk_rq_map_kern(struct request_queue *, struct request *, void *, unsigned int, gfp_t);
 803 extern int blk_rq_map_user_iov(struct request_queue *, struct request *,
 804                                struct rq_map_data *, struct sg_iovec *, int,
 805                                unsigned int, gfp_t);
 806 extern int blk_execute_rq(struct request_queue *, struct gendisk *,
 807                           struct request *, int);
 808 extern void blk_execute_rq_nowait(struct request_queue *, struct gendisk *,
 809                                   struct request *, int, rq_end_io_fn *);
 810 extern void blk_unplug(struct request_queue *q);
 811
 812 static inline struct request_queue *bdev_get_queue(struct block_device *bdev)
 813 {
 814         return bdev->bd_disk->queue;
 815 }
 816
 817 static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
 818                                        struct page *page)
 819 {
 820         if (bdi && bdi->unplug_io_fn)
 821                 bdi->unplug_io_fn(bdi, page);
 822 }
 823
 824 static inline void blk_run_address_space(struct address_space *mapping)
 825 {
 826         if (mapping)
 827                 blk_run_backing_dev(mapping->backing_dev_info, NULL);
 828 }
 829
 830 extern void blkdev_dequeue_request(struct request *req);
 831
 832 /*
 833  * blk_end_request() and friends.
 834  * __blk_end_request() and end_request() must be called with
 835  * the request queue spinlock acquired.
 836  *
 837  * Several drivers define their own end_request and call
 838  * blk_end_request() for parts of the original function.
 839  * This prevents code duplication in drivers.
 840  */
 841 extern int blk_end_request(struct request *rq, int error,
 842                                 unsigned int nr_bytes);
 843 extern int __blk_end_request(struct request *rq, int error,
 844                                 unsigned int nr_bytes);
 845 extern int blk_end_bidi_request(struct request *rq, int error,
 846                                 unsigned int nr_bytes, unsigned int bidi_bytes);
 847 extern void end_request(struct request *, int);
 848 extern int blk_end_request_callback(struct request *rq, int error,
 849                                 unsigned int nr_bytes,
 850                                 int (drv_callback)(struct request *));
 851 extern void blk_complete_request(struct request *);
 852 extern void __blk_complete_request(struct request *);
 853 extern void blk_abort_request(struct request *);
 854 extern void blk_abort_queue(struct request_queue *);
 855 extern void blk_update_request(struct request *rq, int error,
 856                                unsigned int nr_bytes);
 857
 858 /*
 859  * blk_end_request() takes bytes instead of sectors as a complete size.
 860  * blk_rq_bytes() returns bytes left to complete in the entire request.
 861  * blk_rq_cur_bytes() returns bytes left to complete in the current segment.
 862  */
 863 extern unsigned int blk_rq_bytes(struct request *rq);
 864 extern unsigned int blk_rq_cur_bytes(struct request *rq);
 865
 866 /*
 867  * Access functions for manipulating queue properties
 868  */
 869 extern struct request_queue *blk_init_queue_node(request_fn_proc *rfn,
 870                                         spinlock_t *lock, int node_id);
 871 extern struct request_queue *blk_init_queue(request_fn_proc *, spinlock_t *);
 872 extern void blk_cleanup_queue(struct request_queue *);
 873 extern void blk_queue_make_request(struct request_queue *, make_request_fn *);
 874 extern void blk_queue_bounce_limit(struct request_queue *, u64);
 875 extern void blk_queue_max_sectors(struct request_queue *, unsigned int);
 876 extern void blk_queue_max_phys_segments(struct request_queue *, unsigned short);
 877 extern void blk_queue_max_hw_segments(struct request_queue *, unsigned short);
 878 extern void blk_queue_max_segment_size(struct request_queue *, unsigned int);
 879 extern void blk_queue_hardsect_size(struct request_queue *, unsigned short);
 880 extern void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b);
 881 extern void blk_queue_dma_pad(struct request_queue *, unsigned int);
 882 extern void blk_queue_update_dma_pad(struct request_queue *, unsigned int);
 883 extern int blk_queue_dma_drain(struct request_queue *q,
 884                                dma_drain_needed_fn *dma_drain_needed,
 885                                void *buf, unsigned int size);
 886 extern void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn);
 887 extern void blk_queue_segment_boundary(struct request_queue *, unsigned long);
 888 extern void blk_queue_prep_rq(struct request_queue *, prep_rq_fn *pfn);
 889 extern void blk_queue_merge_bvec(struct request_queue *, merge_bvec_fn *);
 890 extern void blk_queue_dma_alignment(struct request_queue *, int);
 891 extern void blk_queue_update_dma_alignment(struct request_queue *, int);
 892 extern void blk_queue_softirq_done(struct request_queue *, softirq_done_fn *);
 893 extern void blk_queue_set_discard(struct request_queue *, prepare_discard_fn *);
 894 extern void blk_queue_rq_timed_out(struct request_queue *, rq_timed_out_fn *);
 895 extern void blk_queue_rq_timeout(struct request_queue *, unsigned int);
 896 extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);
 897 extern int blk_queue_ordered(struct request_queue *, unsigned, prepare_flush_fn *);
 898 extern bool blk_do_ordered(struct request_queue *, struct request **);
 899 extern unsigned blk_ordered_cur_seq(struct request_queue *);
 900 extern unsigned blk_ordered_req_seq(struct request *);
 901 extern bool blk_ordered_complete_seq(struct request_queue *, unsigned, int);
 902
 903 extern int blk_rq_map_sg(struct request_queue *, struct request *, struct scatterlist *);
 904 extern void blk_dump_rq_flags(struct request *, char *);
 905 extern void generic_unplug_device(struct request_queue *);
 906 extern long nr_blockdev_pages(void);
 907
 908 int blk_get_queue(struct request_queue *);
 909 struct request_queue *blk_alloc_queue(gfp_t);
 910 struct request_queue *blk_alloc_queue_node(gfp_t, int);
 911 extern void blk_put_queue(struct request_queue *);
 912
 913 /*
 914  * tag stuff
 915  */
 916 #define blk_rq_tagged(rq)               ((rq)->cmd_flags & REQ_QUEUED)
 917 extern int blk_queue_start_tag(struct request_queue *, struct request *);
 918 extern struct request *blk_queue_find_tag(struct request_queue *, int);
 919 extern void blk_queue_end_tag(struct request_queue *, struct request *);
 920 extern int blk_queue_init_tags(struct request_queue *, int, struct blk_queue_tag *);
 921 extern void blk_queue_free_tags(struct request_queue *);
 922 extern int blk_queue_resize_tags(struct request_queue *, int);
 923 extern void blk_queue_invalidate_tags(struct request_queue *);
 924 extern struct blk_queue_tag *blk_init_tags(int);
 925 extern void blk_free_tags(struct blk_queue_tag *);
 926
 927 static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
 928                                                 int tag)
 929 {
 930         if (unlikely(bqt == NULL || tag >= bqt->real_max_depth))
 931                 return NULL;
 932         return bqt->tag_index[tag];
 933 }
 934
 935 extern int blkdev_issue_flush(struct block_device *, sector_t *);
 936 extern int blkdev_issue_discard(struct block_device *,
 937                                 sector_t sector, sector_t nr_sects, gfp_t);
 938
 939 static inline int sb_issue_discard(struct super_block *sb,
 940                                    sector_t block, sector_t nr_blocks)
 941 {
 942         block <<= (sb->s_blocksize_bits - 9);
 943         nr_blocks <<= (sb->s_blocksize_bits - 9);
 944         return blkdev_issue_discard(sb->s_bdev, block, nr_blocks, GFP_KERNEL);
 945 }
 946
 947 /*
 948 * command filter functions
 949 */
 950 extern int blk_verify_command(struct blk_cmd_filter *filter,
 951                               unsigned char *cmd, fmode_t has_write_perm);
 952 extern void blk_unregister_filter(struct gendisk *disk);
 953 extern void blk_set_cmd_filter_defaults(struct blk_cmd_filter *filter);
 954
 955 #define MAX_PHYS_SEGMENTS 128
 956 #define MAX_HW_SEGMENTS 128
 957 #define SAFE_MAX_SECTORS 255
 958 #define BLK_DEF_MAX_SECTORS 1024
 959
 960 #define MAX_SEGMENT_SIZE        65536
 961
 962 #define BLK_SEG_BOUNDARY_MASK   0xFFFFFFFFUL
 963
 964 #define blkdev_entry_to_request(entry) list_entry((entry), struct request, queuelist)
 965
 966 static inline int queue_hardsect_size(struct request_queue *q)
 967 {
 968         int retval = 512;
 969
 970         if (q && q->hardsect_size)
 971                 retval = q->hardsect_size;
 972
 973         return retval;
 974 }
 975
 976 static inline int bdev_hardsect_size(struct block_device *bdev)
 977 {
 978         return queue_hardsect_size(bdev_get_queue(bdev));
 979 }
 980
 981 static inline int queue_dma_alignment(struct request_queue *q)
 982 {
 983         return q ? q->dma_alignment : 511;
 984 }
 985
 986 static inline int blk_rq_aligned(struct request_queue *q, void *addr,
 987                                  unsigned int len)
 988 {
 989         unsigned int alignment = queue_dma_alignment(q) | q->dma_pad_mask;
 990         return !((unsigned long)addr & alignment) && !(len & alignment);
 991 }
 992
 993 /* assumes size > 256 */
 994 static inline unsigned int blksize_bits(unsigned int size)
 995 {
 996         unsigned int bits = 8;
 997         do {
 998                 bits++;
 999                 size >>= 1;
1000         } while (size > 256);
1001         return bits;
1002 }
1003
1004 static inline unsigned int block_size(struct block_device *bdev)
1005 {
1006         return bdev->bd_block_size;
1007 }
1008
1009 typedef struct {struct page *v;} Sector;
1010
1011 unsigned char *read_dev_sector(struct block_device *, sector_t, Sector *);
1012
1013 static inline void put_dev_sector(Sector p)
1014 {
1015         page_cache_release(p.v);
1016 }
1017
1018 struct work_struct;
1019 int kblockd_schedule_work(struct request_queue *q, struct work_struct *work);
1020
1021 #define MODULE_ALIAS_BLOCKDEV(major,minor) \
1022         MODULE_ALIAS("block-major-" __stringify(major) "-" __stringify(minor))
1023 #define MODULE_ALIAS_BLOCKDEV_MAJOR(major) \
1024         MODULE_ALIAS("block-major-" __stringify(major) "-*")
1025
1026 #if defined(CONFIG_BLK_DEV_INTEGRITY)
1027
1028 #define INTEGRITY_FLAG_READ     2       /* verify data integrity on read */
1029 #define INTEGRITY_FLAG_WRITE    4       /* generate data integrity on write */
1030
1031 struct blk_integrity_exchg {
1032         void                    *prot_buf;
1033         void                    *data_buf;
1034         sector_t                sector;
1035         unsigned int            data_size;
1036         unsigned short          sector_size;
1037         const char              *disk_name;
1038 };
1039
1040 typedef void (integrity_gen_fn) (struct blk_integrity_exchg *);
1041 typedef int (integrity_vrfy_fn) (struct blk_integrity_exchg *);
1042 typedef void (integrity_set_tag_fn) (void *, void *, unsigned int);
1043 typedef void (integrity_get_tag_fn) (void *, void *, unsigned int);
1044
1045 struct blk_integrity {
1046         integrity_gen_fn        *generate_fn;
1047         integrity_vrfy_fn       *verify_fn;
1048         integrity_set_tag_fn    *set_tag_fn;
1049         integrity_get_tag_fn    *get_tag_fn;
1050
1051         unsigned short          flags;
1052         unsigned short          tuple_size;
1053         unsigned short          sector_size;
1054         unsigned short          tag_size;
1055
1056         const char              *name;
1057
1058         struct kobject          kobj;
1059 };
1060
1061 extern int blk_integrity_register(struct gendisk *, struct blk_integrity *);
1062 extern void blk_integrity_unregister(struct gendisk *);
1063 extern int blk_integrity_compare(struct gendisk *, struct gendisk *);
1064 extern int blk_rq_map_integrity_sg(struct request *, struct scatterlist *);
1065 extern int blk_rq_count_integrity_sg(struct request *);
1066
1067 static inline
1068 struct blk_integrity *bdev_get_integrity(struct block_device *bdev)
1069 {
1070         return bdev->bd_disk->integrity;
1071 }
1072
1073 static inline struct blk_integrity *blk_get_integrity(struct gendisk *disk)
1074 {
1075         return disk->integrity;
1076 }
1077
1078 static inline int blk_integrity_rq(struct request *rq)
1079 {
1080         if (rq->bio == NULL)
1081                 return 0;
1082
1083         return bio_integrity(rq->bio);
1084 }
1085
1086 #else /* CONFIG_BLK_DEV_INTEGRITY */
1087
1088 #define blk_integrity_rq(rq)                    (0)
1089 #define blk_rq_count_integrity_sg(a)            (0)
1090 #define blk_rq_map_integrity_sg(a, b)           (0)
1091 #define bdev_get_integrity(a)                   (0)
1092 #define blk_get_integrity(a)                    (0)
1093 #define blk_integrity_compare(a, b)             (0)
1094 #define blk_integrity_register(a, b)            (0)
1095 #define blk_integrity_unregister(a)             do { } while (0);
1096
1097 #endif /* CONFIG_BLK_DEV_INTEGRITY */
1098
1099 struct block_device_operations {
1100         int (*open) (struct block_device *, fmode_t);
1101         int (*release) (struct gendisk *, fmode_t);
1102         int (*locked_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
1103         int (*ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
1104         int (*compat_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
1105         int (*direct_access) (struct block_device *, sector_t,
1106                                                 void **, unsigned long *);
1107         int (*media_changed) (struct gendisk *);
1108         int (*revalidate_disk) (struct gendisk *);
1109         int (*getgeo)(struct block_device *, struct hd_geometry *);
1110         struct module *owner;
1111 };
1112
1113 extern int __blkdev_driver_ioctl(struct block_device *, fmode_t, unsigned int,
1114                                  unsigned long);
1115 #else /* CONFIG_BLOCK */
1116 /*
1117  * stubs for when the block layer is configured out
1118  */
1119 #define buffer_heads_over_limit 0
1120
1121 static inline long nr_blockdev_pages(void)
1122 {
1123         return 0;
1124 }
1125
1126 #endif /* CONFIG_BLOCK */
1127
1128 #endif