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      1 #ifndef _LINUX_BLKDEV_H
      2 #define _LINUX_BLKDEV_H
      3 
      4 #include <linux/major.h>
      5 #include <linux/genhd.h>
      6 #include <linux/list.h>
      7 #include <linux/timer.h>
      8 #include <linux/workqueue.h>
      9 #include <linux/pagemap.h>
     10 #include <linux/backing-dev.h>
     11 #include <linux/wait.h>
     12 #include <linux/mempool.h>
     13 #include <linux/bio.h>
     14 #include <linux/module.h>
     15 #include <linux/stringify.h>
     16 
     17 #include <asm/scatterlist.h>
     18 
     19 struct scsi_ioctl_command;
     20 
     21 struct request_queue;
     22 typedef struct request_queue request_queue_t;
     23 struct elevator_queue;
     24 typedef struct elevator_queue elevator_t;
     25 struct request_pm_state;
     26 struct blk_trace;
     27 
     28 #define BLKDEV_MIN_RQ	4
     29 #define BLKDEV_MAX_RQ	128	/* Default maximum */
     30 
     31 /*
     32  * This is the per-process anticipatory I/O scheduler state.
     33  */
     34 struct as_io_context {
     35 	spinlock_t lock;
     36 
     37 	void (*dtor)(struct as_io_context *aic); /* destructor */
     38 	void (*exit)(struct as_io_context *aic); /* called on task exit */
     39 
     40 	unsigned long state;
     41 	atomic_t nr_queued; /* queued reads & sync writes */
     42 	atomic_t nr_dispatched; /* number of requests gone to the drivers */
     43 
     44 	/* IO History tracking */
     45 	/* Thinktime */
     46 	unsigned long last_end_request;
     47 	unsigned long ttime_total;
     48 	unsigned long ttime_samples;
     49 	unsigned long ttime_mean;
     50 	/* Layout pattern */
     51 	unsigned int seek_samples;
     52 	sector_t last_request_pos;
     53 	u64 seek_total;
     54 	sector_t seek_mean;
     55 };
     56 
     57 struct cfq_queue;
     58 struct cfq_io_context {
     59 	struct rb_node rb_node;
     60 	void *key;
     61 
     62 	struct cfq_queue *cfqq[2];
     63 
     64 	struct io_context *ioc;
     65 
     66 	unsigned long last_end_request;
     67 	sector_t last_request_pos;
     68  	unsigned long last_queue;
     69 
     70 	unsigned long ttime_total;
     71 	unsigned long ttime_samples;
     72 	unsigned long ttime_mean;
     73 
     74 	unsigned int seek_samples;
     75 	u64 seek_total;
     76 	sector_t seek_mean;
     77 
     78 	struct list_head queue_list;
     79 
     80 	void (*dtor)(struct io_context *); /* destructor */
     81 	void (*exit)(struct io_context *); /* called on task exit */
     82 };
     83 
     84 /*
     85  * This is the per-process I/O subsystem state.  It is refcounted and
     86  * kmalloc'ed. Currently all fields are modified in process io context
     87  * (apart from the atomic refcount), so require no locking.
     88  */
     89 struct io_context {
     90 	atomic_t refcount;
     91 	struct task_struct *task;
     92 
     93 	int (*set_ioprio)(struct io_context *, unsigned int);
     94 
     95 	/*
     96 	 * For request batching
     97 	 */
     98 	unsigned long last_waited; /* Time last woken after wait for request */
     99 	int nr_batch_requests;     /* Number of requests left in the batch */
    100 
    101 	struct as_io_context *aic;
    102 	struct rb_root cic_root;
    103 };
    104 
    105 void put_io_context(struct io_context *ioc);
    106 void exit_io_context(void);
    107 struct io_context *current_io_context(gfp_t gfp_flags);
    108 struct io_context *get_io_context(gfp_t gfp_flags);
    109 void copy_io_context(struct io_context **pdst, struct io_context **psrc);
    110 void swap_io_context(struct io_context **ioc1, struct io_context **ioc2);
    111 
    112 struct request;
    113 typedef void (rq_end_io_fn)(struct request *, int);
    114 
    115 struct request_list {
    116 	int count[2];
    117 	int starved[2];
    118 	int elvpriv;
    119 	mempool_t *rq_pool;
    120 	wait_queue_head_t wait[2];
    121 };
    122 
    123 #define BLK_MAX_CDB	16
    124 
    125 /*
    126  * try to put the fields that are referenced together in the same cacheline
    127  */
    128 struct request {
    129 	struct list_head queuelist;
    130 	struct list_head donelist;
    131 
    132 	unsigned long flags;		/* see REQ_ bits below */
    133 
    134 	/* Maintain bio traversal state for part by part I/O submission.
    135 	 * hard_* are block layer internals, no driver should touch them!
    136 	 */
    137 
    138 	sector_t sector;		/* next sector to submit */
    139 	unsigned long nr_sectors;	/* no. of sectors left to submit */
    140 	/* no. of sectors left to submit in the current segment */
    141 	unsigned int current_nr_sectors;
    142 
    143 	sector_t hard_sector;		/* next sector to complete */
    144 	unsigned long hard_nr_sectors;	/* no. of sectors left to complete */
    145 	/* no. of sectors left to complete in the current segment */
    146 	unsigned int hard_cur_sectors;
    147 
    148 	struct bio *bio;
    149 	struct bio *biotail;
    150 
    151 	void *elevator_private;
    152 	void *completion_data;
    153 
    154 	int rq_status;	/* should split this into a few status bits */
    155 	int errors;
    156 	struct gendisk *rq_disk;
    157 	unsigned long start_time;
    158 
    159 	/* Number of scatter-gather DMA addr+len pairs after
    160 	 * physical address coalescing is performed.
    161 	 */
    162 	unsigned short nr_phys_segments;
    163 
    164 	/* Number of scatter-gather addr+len pairs after
    165 	 * physical and DMA remapping hardware coalescing is performed.
    166 	 * This is the number of scatter-gather entries the driver
    167 	 * will actually have to deal with after DMA mapping is done.
    168 	 */
    169 	unsigned short nr_hw_segments;
    170 
    171 	unsigned short ioprio;
    172 
    173 	int tag;
    174 
    175 	int ref_count;
    176 	request_queue_t *q;
    177 	struct request_list *rl;
    178 
    179 	struct completion *waiting;
    180 	void *special;
    181 	char *buffer;
    182 
    183 	/*
    184 	 * when request is used as a packet command carrier
    185 	 */
    186 	unsigned int cmd_len;
    187 	unsigned char cmd[BLK_MAX_CDB];
    188 
    189 	unsigned int data_len;
    190 	unsigned int sense_len;
    191 	void *data;
    192 	void *sense;
    193 
    194 	unsigned int timeout;
    195 	int retries;
    196 
    197 	/*
    198 	 * completion callback. end_io_data should be folded in with waiting
    199 	 */
    200 	rq_end_io_fn *end_io;
    201 	void *end_io_data;
    202 };
    203 
    204 /*
    205  * first three bits match BIO_RW* bits, important
    206  */
    207 enum rq_flag_bits {
    208 	__REQ_RW,		/* not set, read. set, write */
    209 	__REQ_FAILFAST,		/* no low level driver retries */
    210 	__REQ_SORTED,		/* elevator knows about this request */
    211 	__REQ_SOFTBARRIER,	/* may not be passed by ioscheduler */
    212 	__REQ_HARDBARRIER,	/* may not be passed by drive either */
    213 	__REQ_FUA,		/* forced unit access */
    214 	__REQ_CMD,		/* is a regular fs rw request */
    215 	__REQ_NOMERGE,		/* don't touch this for merging */
    216 	__REQ_STARTED,		/* drive already may have started this one */
    217 	__REQ_DONTPREP,		/* don't call prep for this one */
    218 	__REQ_QUEUED,		/* uses queueing */
    219 	__REQ_ELVPRIV,		/* elevator private data attached */
    220 	/*
    221 	 * for ATA/ATAPI devices
    222 	 */
    223 	__REQ_PC,		/* packet command (special) */
    224 	__REQ_BLOCK_PC,		/* queued down pc from block layer */
    225 	__REQ_SENSE,		/* sense retrival */
    226 
    227 	__REQ_FAILED,		/* set if the request failed */
    228 	__REQ_QUIET,		/* don't worry about errors */
    229 	__REQ_SPECIAL,		/* driver suplied command */
    230 	__REQ_DRIVE_CMD,
    231 	__REQ_DRIVE_TASK,
    232 	__REQ_DRIVE_TASKFILE,
    233 	__REQ_PREEMPT,		/* set for "ide_preempt" requests */
    234 	__REQ_PM_SUSPEND,	/* suspend request */
    235 	__REQ_PM_RESUME,	/* resume request */
    236 	__REQ_PM_SHUTDOWN,	/* shutdown request */
    237 	__REQ_ORDERED_COLOR,	/* is before or after barrier */
    238 	__REQ_RW_SYNC,		/* request is sync (O_DIRECT) */
    239 	__REQ_NR_BITS,		/* stops here */
    240 };
    241 
    242 #define REQ_RW		(1 << __REQ_RW)
    243 #define REQ_FAILFAST	(1 << __REQ_FAILFAST)
    244 #define REQ_SORTED	(1 << __REQ_SORTED)
    245 #define REQ_SOFTBARRIER	(1 << __REQ_SOFTBARRIER)
    246 #define REQ_HARDBARRIER	(1 << __REQ_HARDBARRIER)
    247 #define REQ_FUA		(1 << __REQ_FUA)
    248 #define REQ_CMD		(1 << __REQ_CMD)
    249 #define REQ_NOMERGE	(1 << __REQ_NOMERGE)
    250 #define REQ_STARTED	(1 << __REQ_STARTED)
    251 #define REQ_DONTPREP	(1 << __REQ_DONTPREP)
    252 #define REQ_QUEUED	(1 << __REQ_QUEUED)
    253 #define REQ_ELVPRIV	(1 << __REQ_ELVPRIV)
    254 #define REQ_PC		(1 << __REQ_PC)
    255 #define REQ_BLOCK_PC	(1 << __REQ_BLOCK_PC)
    256 #define REQ_SENSE	(1 << __REQ_SENSE)
    257 #define REQ_FAILED	(1 << __REQ_FAILED)
    258 #define REQ_QUIET	(1 << __REQ_QUIET)
    259 #define REQ_SPECIAL	(1 << __REQ_SPECIAL)
    260 #define REQ_DRIVE_CMD	(1 << __REQ_DRIVE_CMD)
    261 #define REQ_DRIVE_TASK	(1 << __REQ_DRIVE_TASK)
    262 #define REQ_DRIVE_TASKFILE	(1 << __REQ_DRIVE_TASKFILE)
    263 #define REQ_PREEMPT	(1 << __REQ_PREEMPT)
    264 #define REQ_PM_SUSPEND	(1 << __REQ_PM_SUSPEND)
    265 #define REQ_PM_RESUME	(1 << __REQ_PM_RESUME)
    266 #define REQ_PM_SHUTDOWN	(1 << __REQ_PM_SHUTDOWN)
    267 #define REQ_ORDERED_COLOR	(1 << __REQ_ORDERED_COLOR)
    268 #define REQ_RW_SYNC	(1 << __REQ_RW_SYNC)
    269 
    270 /*
    271  * State information carried for REQ_PM_SUSPEND and REQ_PM_RESUME
    272  * requests. Some step values could eventually be made generic.
    273  */
    274 struct request_pm_state
    275 {
    276 	/* PM state machine step value, currently driver specific */
    277 	int	pm_step;
    278 	/* requested PM state value (S1, S2, S3, S4, ...) */
    279 	u32	pm_state;
    280 	void*	data;		/* for driver use */
    281 };
    282 
    283 #include <linux/elevator.h>
    284 
    285 typedef int (merge_request_fn) (request_queue_t *, struct request *,
    286 				struct bio *);
    287 typedef int (merge_requests_fn) (request_queue_t *, struct request *,
    288 				 struct request *);
    289 typedef void (request_fn_proc) (request_queue_t *q);
    290 typedef int (make_request_fn) (request_queue_t *q, struct bio *bio);
    291 typedef int (prep_rq_fn) (request_queue_t *, struct request *);
    292 typedef void (unplug_fn) (request_queue_t *);
    293 
    294 struct bio_vec;
    295 typedef int (merge_bvec_fn) (request_queue_t *, struct bio *, struct bio_vec *);
    296 typedef void (activity_fn) (void *data, int rw);
    297 typedef int (issue_flush_fn) (request_queue_t *, struct gendisk *, sector_t *);
    298 typedef void (prepare_flush_fn) (request_queue_t *, struct request *);
    299 typedef void (softirq_done_fn)(struct request *);
    300 
    301 enum blk_queue_state {
    302 	Queue_down,
    303 	Queue_up,
    304 };
    305 
    306 struct blk_queue_tag {
    307 	struct request **tag_index;	/* map of busy tags */
    308 	unsigned long *tag_map;		/* bit map of free/busy tags */
    309 	struct list_head busy_list;	/* fifo list of busy tags */
    310 	int busy;			/* current depth */
    311 	int max_depth;			/* what we will send to device */
    312 	int real_max_depth;		/* what the array can hold */
    313 	atomic_t refcnt;		/* map can be shared */
    314 };
    315 
    316 struct request_queue
    317 {
    318 	/*
    319 	 * Together with queue_head for cacheline sharing
    320 	 */
    321 	struct list_head	queue_head;
    322 	struct request		*last_merge;
    323 	elevator_t		*elevator;
    324 
    325 	/*
    326 	 * the queue request freelist, one for reads and one for writes
    327 	 */
    328 	struct request_list	rq;
    329 
    330 	request_fn_proc		*request_fn;
    331 	merge_request_fn	*back_merge_fn;
    332 	merge_request_fn	*front_merge_fn;
    333 	merge_requests_fn	*merge_requests_fn;
    334 	make_request_fn		*make_request_fn;
    335 	prep_rq_fn		*prep_rq_fn;
    336 	unplug_fn		*unplug_fn;
    337 	merge_bvec_fn		*merge_bvec_fn;
    338 	activity_fn		*activity_fn;
    339 	issue_flush_fn		*issue_flush_fn;
    340 	prepare_flush_fn	*prepare_flush_fn;
    341 	softirq_done_fn		*softirq_done_fn;
    342 
    343 	/*
    344 	 * Dispatch queue sorting
    345 	 */
    346 	sector_t		end_sector;
    347 	struct request		*boundary_rq;
    348 
    349 	/*
    350 	 * Auto-unplugging state
    351 	 */
    352 	struct timer_list	unplug_timer;
    353 	int			unplug_thresh;	/* After this many requests */
    354 	unsigned long		unplug_delay;	/* After this many jiffies */
    355 	struct work_struct	unplug_work;
    356 
    357 	struct backing_dev_info	backing_dev_info;
    358 
    359 	/*
    360 	 * The queue owner gets to use this for whatever they like.
    361 	 * ll_rw_blk doesn't touch it.
    362 	 */
    363 	void			*queuedata;
    364 
    365 	void			*activity_data;
    366 
    367 	/*
    368 	 * queue needs bounce pages for pages above this limit
    369 	 */
    370 	unsigned long		bounce_pfn;
    371 	gfp_t			bounce_gfp;
    372 
    373 	/*
    374 	 * various queue flags, see QUEUE_* below
    375 	 */
    376 	unsigned long		queue_flags;
    377 
    378 	/*
    379 	 * protects queue structures from reentrancy. ->__queue_lock should
    380 	 * _never_ be used directly, it is queue private. always use
    381 	 * ->queue_lock.
    382 	 */
    383 	spinlock_t		__queue_lock;
    384 	spinlock_t		*queue_lock;
    385 
    386 	/*
    387 	 * queue kobject
    388 	 */
    389 	struct kobject kobj;
    390 
    391 	/*
    392 	 * queue settings
    393 	 */
    394 	unsigned long		nr_requests;	/* Max # of requests */
    395 	unsigned int		nr_congestion_on;
    396 	unsigned int		nr_congestion_off;
    397 	unsigned int		nr_batching;
    398 
    399 	unsigned int		max_sectors;
    400 	unsigned int		max_hw_sectors;
    401 	unsigned short		max_phys_segments;
    402 	unsigned short		max_hw_segments;
    403 	unsigned short		hardsect_size;
    404 	unsigned int		max_segment_size;
    405 
    406 	unsigned long		seg_boundary_mask;
    407 	unsigned int		dma_alignment;
    408 
    409 	struct blk_queue_tag	*queue_tags;
    410 
    411 	unsigned int		nr_sorted;
    412 	unsigned int		in_flight;
    413 
    414 	/*
    415 	 * sg stuff
    416 	 */
    417 	unsigned int		sg_timeout;
    418 	unsigned int		sg_reserved_size;
    419 	int			node;
    420 
    421 	struct blk_trace	*blk_trace;
    422 
    423 	/*
    424 	 * reserved for flush operations
    425 	 */
    426 	unsigned int		ordered, next_ordered, ordseq;
    427 	int			orderr, ordcolor;
    428 	struct request		pre_flush_rq, bar_rq, post_flush_rq;
    429 	struct request		*orig_bar_rq;
    430 	unsigned int		bi_size;
    431 
    432 	struct mutex		sysfs_lock;
    433 };
    434 
    435 #define RQ_INACTIVE		(-1)
    436 #define RQ_ACTIVE		1
    437 
    438 #define QUEUE_FLAG_CLUSTER	0	/* cluster several segments into 1 */
    439 #define QUEUE_FLAG_QUEUED	1	/* uses generic tag queueing */
    440 #define QUEUE_FLAG_STOPPED	2	/* queue is stopped */
    441 #define	QUEUE_FLAG_READFULL	3	/* write queue has been filled */
    442 #define QUEUE_FLAG_WRITEFULL	4	/* read queue has been filled */
    443 #define QUEUE_FLAG_DEAD		5	/* queue being torn down */
    444 #define QUEUE_FLAG_REENTER	6	/* Re-entrancy avoidance */
    445 #define QUEUE_FLAG_PLUGGED	7	/* queue is plugged */
    446 #define QUEUE_FLAG_ELVSWITCH	8	/* don't use elevator, just do FIFO */
    447 
    448 enum {
    449 	/*
    450 	 * Hardbarrier is supported with one of the following methods.
    451 	 *
    452 	 * NONE		: hardbarrier unsupported
    453 	 * DRAIN	: ordering by draining is enough
    454 	 * DRAIN_FLUSH	: ordering by draining w/ pre and post flushes
    455 	 * DRAIN_FUA	: ordering by draining w/ pre flush and FUA write
    456 	 * TAG		: ordering by tag is enough
    457 	 * TAG_FLUSH	: ordering by tag w/ pre and post flushes
    458 	 * TAG_FUA	: ordering by tag w/ pre flush and FUA write
    459 	 */
    460 	QUEUE_ORDERED_NONE	= 0x00,
    461 	QUEUE_ORDERED_DRAIN	= 0x01,
    462 	QUEUE_ORDERED_TAG	= 0x02,
    463 
    464 	QUEUE_ORDERED_PREFLUSH	= 0x10,
    465 	QUEUE_ORDERED_POSTFLUSH	= 0x20,
    466 	QUEUE_ORDERED_FUA	= 0x40,
    467 
    468 	QUEUE_ORDERED_DRAIN_FLUSH = QUEUE_ORDERED_DRAIN |
    469 			QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH,
    470 	QUEUE_ORDERED_DRAIN_FUA	= QUEUE_ORDERED_DRAIN |
    471 			QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_FUA,
    472 	QUEUE_ORDERED_TAG_FLUSH	= QUEUE_ORDERED_TAG |
    473 			QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH,
    474 	QUEUE_ORDERED_TAG_FUA	= QUEUE_ORDERED_TAG |
    475 			QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_FUA,
    476 
    477 	/*
    478 	 * Ordered operation sequence
    479 	 */
    480 	QUEUE_ORDSEQ_STARTED	= 0x01,	/* flushing in progress */
    481 	QUEUE_ORDSEQ_DRAIN	= 0x02,	/* waiting for the queue to be drained */
    482 	QUEUE_ORDSEQ_PREFLUSH	= 0x04,	/* pre-flushing in progress */
    483 	QUEUE_ORDSEQ_BAR	= 0x08,	/* original barrier req in progress */
    484 	QUEUE_ORDSEQ_POSTFLUSH	= 0x10,	/* post-flushing in progress */
    485 	QUEUE_ORDSEQ_DONE	= 0x20,
    486 };
    487 
    488 #define blk_queue_plugged(q)	test_bit(QUEUE_FLAG_PLUGGED, &(q)->queue_flags)
    489 #define blk_queue_tagged(q)	test_bit(QUEUE_FLAG_QUEUED, &(q)->queue_flags)
    490 #define blk_queue_stopped(q)	test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
    491 #define blk_queue_flushing(q)	((q)->ordseq)
    492 
    493 #define blk_fs_request(rq)	((rq)->flags & REQ_CMD)
    494 #define blk_pc_request(rq)	((rq)->flags & REQ_BLOCK_PC)
    495 #define blk_noretry_request(rq)	((rq)->flags & REQ_FAILFAST)
    496 #define blk_rq_started(rq)	((rq)->flags & REQ_STARTED)
    497 
    498 #define blk_account_rq(rq)	(blk_rq_started(rq) && blk_fs_request(rq))
    499 
    500 #define blk_pm_suspend_request(rq)	((rq)->flags & REQ_PM_SUSPEND)
    501 #define blk_pm_resume_request(rq)	((rq)->flags & REQ_PM_RESUME)
    502 #define blk_pm_request(rq)	\
    503 	((rq)->flags & (REQ_PM_SUSPEND | REQ_PM_RESUME))
    504 
    505 #define blk_sorted_rq(rq)	((rq)->flags & REQ_SORTED)
    506 #define blk_barrier_rq(rq)	((rq)->flags & REQ_HARDBARRIER)
    507 #define blk_fua_rq(rq)		((rq)->flags & REQ_FUA)
    508 
    509 #define list_entry_rq(ptr)	list_entry((ptr), struct request, queuelist)
    510 
    511 #define rq_data_dir(rq)		((rq)->flags & 1)
    512 
    513 static inline int blk_queue_full(struct request_queue *q, int rw)
    514 {
    515 	if (rw == READ)
    516 		return test_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
    517 	return test_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
    518 }
    519 
    520 static inline void blk_set_queue_full(struct request_queue *q, int rw)
    521 {
    522 	if (rw == READ)
    523 		set_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
    524 	else
    525 		set_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
    526 }
    527 
    528 static inline void blk_clear_queue_full(struct request_queue *q, int rw)
    529 {
    530 	if (rw == READ)
    531 		clear_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
    532 	else
    533 		clear_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
    534 }
    535 
    536 
    537 /*
    538  * mergeable request must not have _NOMERGE or _BARRIER bit set, nor may
    539  * it already be started by driver.
    540  */
    541 #define RQ_NOMERGE_FLAGS	\
    542 	(REQ_NOMERGE | REQ_STARTED | REQ_HARDBARRIER | REQ_SOFTBARRIER)
    543 #define rq_mergeable(rq)	\
    544 	(!((rq)->flags & RQ_NOMERGE_FLAGS) && blk_fs_request((rq)))
    545 
    546 /*
    547  * noop, requests are automagically marked as active/inactive by I/O
    548  * scheduler -- see elv_next_request
    549  */
    550 #define blk_queue_headactive(q, head_active)
    551 
    552 /*
    553  * q->prep_rq_fn return values
    554  */
    555 #define BLKPREP_OK		0	/* serve it */
    556 #define BLKPREP_KILL		1	/* fatal error, kill */
    557 #define BLKPREP_DEFER		2	/* leave on queue */
    558 
    559 extern unsigned long blk_max_low_pfn, blk_max_pfn;
    560 
    561 /*
    562  * standard bounce addresses:
    563  *
    564  * BLK_BOUNCE_HIGH	: bounce all highmem pages
    565  * BLK_BOUNCE_ANY	: don't bounce anything
    566  * BLK_BOUNCE_ISA	: bounce pages above ISA DMA boundary
    567  */
    568 #define BLK_BOUNCE_HIGH		((u64)blk_max_low_pfn << PAGE_SHIFT)
    569 #define BLK_BOUNCE_ANY		((u64)blk_max_pfn << PAGE_SHIFT)
    570 #define BLK_BOUNCE_ISA		(ISA_DMA_THRESHOLD)
    571 
    572 #ifdef CONFIG_MMU
    573 extern int init_emergency_isa_pool(void);
    574 extern void blk_queue_bounce(request_queue_t *q, struct bio **bio);
    575 #else
    576 static inline int init_emergency_isa_pool(void)
    577 {
    578 	return 0;
    579 }
    580 static inline void blk_queue_bounce(request_queue_t *q, struct bio **bio)
    581 {
    582 }
    583 #endif /* CONFIG_MMU */
    584 
    585 #define rq_for_each_bio(_bio, rq)	\
    586 	if ((rq->bio))			\
    587 		for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)
    588 
    589 struct sec_size {
    590 	unsigned block_size;
    591 	unsigned block_size_bits;
    592 };
    593 
    594 extern int blk_register_queue(struct gendisk *disk);
    595 extern void blk_unregister_queue(struct gendisk *disk);
    596 extern void register_disk(struct gendisk *dev);
    597 extern void generic_make_request(struct bio *bio);
    598 extern void blk_put_request(struct request *);
    599 extern void __blk_put_request(request_queue_t *, struct request *);
    600 extern void blk_end_sync_rq(struct request *rq, int error);
    601 extern struct request *blk_get_request(request_queue_t *, int, gfp_t);
    602 extern void blk_insert_request(request_queue_t *, struct request *, int, void *);
    603 extern void blk_requeue_request(request_queue_t *, struct request *);
    604 extern void blk_plug_device(request_queue_t *);
    605 extern int blk_remove_plug(request_queue_t *);
    606 extern void blk_recount_segments(request_queue_t *, struct bio *);
    607 extern int scsi_cmd_ioctl(struct file *, struct gendisk *, unsigned int, void __user *);
    608 extern int sg_scsi_ioctl(struct file *, struct request_queue *,
    609 		struct gendisk *, struct scsi_ioctl_command __user *);
    610 extern void blk_start_queue(request_queue_t *q);
    611 extern void blk_stop_queue(request_queue_t *q);
    612 extern void blk_sync_queue(struct request_queue *q);
    613 extern void __blk_stop_queue(request_queue_t *q);
    614 extern void blk_run_queue(request_queue_t *);
    615 extern void blk_queue_activity_fn(request_queue_t *, activity_fn *, void *);
    616 extern int blk_rq_map_user(request_queue_t *, struct request *, void __user *, unsigned int);
    617 extern int blk_rq_unmap_user(struct bio *, unsigned int);
    618 extern int blk_rq_map_kern(request_queue_t *, struct request *, void *, unsigned int, gfp_t);
    619 extern int blk_rq_map_user_iov(request_queue_t *, struct request *, struct sg_iovec *, int);
    620 extern int blk_execute_rq(request_queue_t *, struct gendisk *,
    621 			  struct request *, int);
    622 extern void blk_execute_rq_nowait(request_queue_t *, struct gendisk *,
    623 				  struct request *, int, rq_end_io_fn *);
    624 
    625 static inline request_queue_t *bdev_get_queue(struct block_device *bdev)
    626 {
    627 	return bdev->bd_disk->queue;
    628 }
    629 
    630 static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
    631 				       struct page *page)
    632 {
    633 	if (bdi && bdi->unplug_io_fn)
    634 		bdi->unplug_io_fn(bdi, page);
    635 }
    636 
    637 static inline void blk_run_address_space(struct address_space *mapping)
    638 {
    639 	if (mapping)
    640 		blk_run_backing_dev(mapping->backing_dev_info, NULL);
    641 }
    642 
    643 /*
    644  * end_request() and friends. Must be called with the request queue spinlock
    645  * acquired. All functions called within end_request() _must_be_ atomic.
    646  *
    647  * Several drivers define their own end_request and call
    648  * end_that_request_first() and end_that_request_last()
    649  * for parts of the original function. This prevents
    650  * code duplication in drivers.
    651  */
    652 extern int end_that_request_first(struct request *, int, int);
    653 extern int end_that_request_chunk(struct request *, int, int);
    654 extern void end_that_request_last(struct request *, int);
    655 extern void end_request(struct request *req, int uptodate);
    656 extern void blk_complete_request(struct request *);
    657 
    658 static inline int rq_all_done(struct request *rq, unsigned int nr_bytes)
    659 {
    660 	if (blk_fs_request(rq))
    661 		return (nr_bytes >= (rq->hard_nr_sectors << 9));
    662 	else if (blk_pc_request(rq))
    663 		return nr_bytes >= rq->data_len;
    664 
    665 	return 0;
    666 }
    667 
    668 /*
    669  * end_that_request_first/chunk() takes an uptodate argument. we account
    670  * any value <= as an io error. 0 means -EIO for compatability reasons,
    671  * any other < 0 value is the direct error type. An uptodate value of
    672  * 1 indicates successful io completion
    673  */
    674 #define end_io_error(uptodate)	(unlikely((uptodate) <= 0))
    675 
    676 static inline void blkdev_dequeue_request(struct request *req)
    677 {
    678 	elv_dequeue_request(req->q, req);
    679 }
    680 
    681 /*
    682  * This should be in elevator.h, but that requires pulling in rq and q
    683  */
    684 static inline void elv_dispatch_add_tail(struct request_queue *q,
    685 					 struct request *rq)
    686 {
    687 	if (q->last_merge == rq)
    688 		q->last_merge = NULL;
    689 	q->nr_sorted--;
    690 
    691 	q->end_sector = rq_end_sector(rq);
    692 	q->boundary_rq = rq;
    693 	list_add_tail(&rq->queuelist, &q->queue_head);
    694 }
    695 
    696 /*
    697  * Access functions for manipulating queue properties
    698  */
    699 extern request_queue_t *blk_init_queue_node(request_fn_proc *rfn,
    700 					spinlock_t *lock, int node_id);
    701 extern request_queue_t *blk_init_queue(request_fn_proc *, spinlock_t *);
    702 extern void blk_cleanup_queue(request_queue_t *);
    703 extern void blk_queue_make_request(request_queue_t *, make_request_fn *);
    704 extern void blk_queue_bounce_limit(request_queue_t *, u64);
    705 extern void blk_queue_max_sectors(request_queue_t *, unsigned int);
    706 extern void blk_queue_max_phys_segments(request_queue_t *, unsigned short);
    707 extern void blk_queue_max_hw_segments(request_queue_t *, unsigned short);
    708 extern void blk_queue_max_segment_size(request_queue_t *, unsigned int);
    709 extern void blk_queue_hardsect_size(request_queue_t *, unsigned short);
    710 extern void blk_queue_stack_limits(request_queue_t *t, request_queue_t *b);
    711 extern void blk_queue_segment_boundary(request_queue_t *, unsigned long);
    712 extern void blk_queue_prep_rq(request_queue_t *, prep_rq_fn *pfn);
    713 extern void blk_queue_merge_bvec(request_queue_t *, merge_bvec_fn *);
    714 extern void blk_queue_dma_alignment(request_queue_t *, int);
    715 extern void blk_queue_softirq_done(request_queue_t *, softirq_done_fn *);
    716 extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);
    717 extern int blk_queue_ordered(request_queue_t *, unsigned, prepare_flush_fn *);
    718 extern void blk_queue_issue_flush_fn(request_queue_t *, issue_flush_fn *);
    719 extern int blk_do_ordered(request_queue_t *, struct request **);
    720 extern unsigned blk_ordered_cur_seq(request_queue_t *);
    721 extern unsigned blk_ordered_req_seq(struct request *);
    722 extern void blk_ordered_complete_seq(request_queue_t *, unsigned, int);
    723 
    724 extern int blk_rq_map_sg(request_queue_t *, struct request *, struct scatterlist *);
    725 extern void blk_dump_rq_flags(struct request *, char *);
    726 extern void generic_unplug_device(request_queue_t *);
    727 extern void __generic_unplug_device(request_queue_t *);
    728 extern long nr_blockdev_pages(void);
    729 
    730 int blk_get_queue(request_queue_t *);
    731 request_queue_t *blk_alloc_queue(gfp_t);
    732 request_queue_t *blk_alloc_queue_node(gfp_t, int);
    733 extern void blk_put_queue(request_queue_t *);
    734 
    735 /*
    736  * tag stuff
    737  */
    738 #define blk_queue_tag_depth(q)		((q)->queue_tags->busy)
    739 #define blk_queue_tag_queue(q)		((q)->queue_tags->busy < (q)->queue_tags->max_depth)
    740 #define blk_rq_tagged(rq)		((rq)->flags & REQ_QUEUED)
    741 extern int blk_queue_start_tag(request_queue_t *, struct request *);
    742 extern struct request *blk_queue_find_tag(request_queue_t *, int);
    743 extern void blk_queue_end_tag(request_queue_t *, struct request *);
    744 extern int blk_queue_init_tags(request_queue_t *, int, struct blk_queue_tag *);
    745 extern void blk_queue_free_tags(request_queue_t *);
    746 extern int blk_queue_resize_tags(request_queue_t *, int);
    747 extern void blk_queue_invalidate_tags(request_queue_t *);
    748 extern long blk_congestion_wait(int rw, long timeout);
    749 
    750 extern void blk_rq_bio_prep(request_queue_t *, struct request *, struct bio *);
    751 extern int blkdev_issue_flush(struct block_device *, sector_t *);
    752 
    753 #define MAX_PHYS_SEGMENTS 128
    754 #define MAX_HW_SEGMENTS 128
    755 #define SAFE_MAX_SECTORS 255
    756 #define BLK_DEF_MAX_SECTORS 1024
    757 
    758 #define MAX_SEGMENT_SIZE	65536
    759 
    760 #define blkdev_entry_to_request(entry) list_entry((entry), struct request, queuelist)
    761 
    762 static inline int queue_hardsect_size(request_queue_t *q)
    763 {
    764 	int retval = 512;
    765 
    766 	if (q && q->hardsect_size)
    767 		retval = q->hardsect_size;
    768 
    769 	return retval;
    770 }
    771 
    772 static inline int bdev_hardsect_size(struct block_device *bdev)
    773 {
    774 	return queue_hardsect_size(bdev_get_queue(bdev));
    775 }
    776 
    777 static inline int queue_dma_alignment(request_queue_t *q)
    778 {
    779 	int retval = 511;
    780 
    781 	if (q && q->dma_alignment)
    782 		retval = q->dma_alignment;
    783 
    784 	return retval;
    785 }
    786 
    787 static inline int bdev_dma_aligment(struct block_device *bdev)
    788 {
    789 	return queue_dma_alignment(bdev_get_queue(bdev));
    790 }
    791 
    792 #define blk_finished_io(nsects)	do { } while (0)
    793 #define blk_started_io(nsects)	do { } while (0)
    794 
    795 /* assumes size > 256 */
    796 static inline unsigned int blksize_bits(unsigned int size)
    797 {
    798 	unsigned int bits = 8;
    799 	do {
    800 		bits++;
    801 		size >>= 1;
    802 	} while (size > 256);
    803 	return bits;
    804 }
    805 
    806 static inline unsigned int block_size(struct block_device *bdev)
    807 {
    808 	return bdev->bd_block_size;
    809 }
    810 
    811 typedef struct {struct page *v;} Sector;
    812 
    813 unsigned char *read_dev_sector(struct block_device *, sector_t, Sector *);
    814 
    815 static inline void put_dev_sector(Sector p)
    816 {
    817 	page_cache_release(p.v);
    818 }
    819 
    820 struct work_struct;
    821 int kblockd_schedule_work(struct work_struct *work);
    822 void kblockd_flush(void);
    823 
    824 #ifdef CONFIG_LBD
    825 # include <asm/div64.h>
    826 # define sector_div(a, b) do_div(a, b)
    827 #else
    828 # define sector_div(n, b)( \
    829 { \
    830 	int _res; \
    831 	_res = (n) % (b); \
    832 	(n) /= (b); \
    833 	_res; \
    834 } \
    835 )
    836 #endif
    837 
    838 #define MODULE_ALIAS_BLOCKDEV(major,minor) \
    839 	MODULE_ALIAS("block-major-" __stringify(major) "-" __stringify(minor))
    840 #define MODULE_ALIAS_BLOCKDEV_MAJOR(major) \
    841 	MODULE_ALIAS("block-major-" __stringify(major) "-*")
    842 
    843 
    844 #endif
    845