blkdev.h

此工具是arm-linux-GCC交叉编译工具（cross-3.4.4）

#ifndef _LINUX_BLKDEV_H
#define _LINUX_BLKDEV_H

#include <linux/config.h>
#include <linux/major.h>
#include <linux/genhd.h>
#include <linux/list.h>
#include <linux/timer.h>
#include <linux/workqueue.h>
#include <linux/pagemap.h>
#include <linux/backing-dev.h>
#include <linux/wait.h>
#include <linux/mempool.h>
#include <linux/bio.h>
#include <linux/module.h>
#include <linux/stringify.h>

#include <asm/scatterlist.h>

struct request_queue;
typedef struct request_queue request_queue_t;
struct elevator_queue;
typedef struct elevator_queue elevator_t;
struct request_pm_state;

#define BLKDEV_MIN_RQ	4
#define BLKDEV_MAX_RQ	128	/* Default maximum */

/*
 * This is the per-process anticipatory I/O scheduler state.
 */
struct as_io_context {
	spinlock_t lock;

	void (*dtor)(struct as_io_context *aic); /* destructor */
	void (*exit)(struct as_io_context *aic); /* called on task exit */

	unsigned long state;
	atomic_t nr_queued; /* queued reads & sync writes */
	atomic_t nr_dispatched; /* number of requests gone to the drivers */

	/* IO History tracking */
	/* Thinktime */
	unsigned long last_end_request;
	unsigned long ttime_total;
	unsigned long ttime_samples;
	unsigned long ttime_mean;
	/* Layout pattern */
	unsigned int seek_samples;
	sector_t last_request_pos;
	u64 seek_total;
	sector_t seek_mean;
};

struct cfq_queue;
struct cfq_io_context {
	/*
	 * circular list of cfq_io_contexts belonging to a process io context
	 */
	struct list_head list;
	struct cfq_queue *cfqq;
	void *key;

	struct io_context *ioc;

	unsigned long last_end_request;
	unsigned long last_queue;
	unsigned long ttime_total;
	unsigned long ttime_samples;
	unsigned long ttime_mean;

	void (*dtor)(struct cfq_io_context *);
	void (*exit)(struct cfq_io_context *);
};

/*
 * This is the per-process I/O subsystem state.  It is refcounted and
 * kmalloc'ed. Currently all fields are modified in process io context
 * (apart from the atomic refcount), so require no locking.
 */
struct io_context {
	atomic_t refcount;
	struct task_struct *task;

	int (*set_ioprio)(struct io_context *, unsigned int);

	/*
	 * For request batching
	 */
	unsigned long last_waited; /* Time last woken after wait for request */
	int nr_batch_requests;     /* Number of requests left in the batch */

	struct as_io_context *aic;
	struct cfq_io_context *cic;
};

void put_io_context(struct io_context *ioc);
void exit_io_context(void);
struct io_context *current_io_context(int gfp_flags);
struct io_context *get_io_context(int gfp_flags);
void copy_io_context(struct io_context **pdst, struct io_context **psrc);
void swap_io_context(struct io_context **ioc1, struct io_context **ioc2);

struct request;
typedef void (rq_end_io_fn)(struct request *);

struct request_list {
	int count[2];
	int starved[2];
	mempool_t *rq_pool;
	wait_queue_head_t wait[2];
	wait_queue_head_t drain;
};

#define BLK_MAX_CDB	16

/*
 * try to put the fields that are referenced together in the same cacheline
 */
struct request {
	struct list_head queuelist; /* looking for ->queue? you must _not_
				     * access it directly, use
				     * blkdev_dequeue_request! */
	unsigned long flags;		/* see REQ_ bits below */

	/* Maintain bio traversal state for part by part I/O submission.
	 * hard_* are block layer internals, no driver should touch them!
	 */

	sector_t sector;		/* next sector to submit */
	unsigned long nr_sectors;	/* no. of sectors left to submit */
	/* no. of sectors left to submit in the current segment */
	unsigned int current_nr_sectors;

	sector_t hard_sector;		/* next sector to complete */
	unsigned long hard_nr_sectors;	/* no. of sectors left to complete */
	/* no. of sectors left to complete in the current segment */
	unsigned int hard_cur_sectors;

	struct bio *bio;
	struct bio *biotail;

	void *elevator_private;

	unsigned short ioprio;

	int rq_status;	/* should split this into a few status bits */
	struct gendisk *rq_disk;
	int errors;
	unsigned long start_time;

	/* Number of scatter-gather DMA addr+len pairs after
	 * physical address coalescing is performed.
	 */
	unsigned short nr_phys_segments;

	/* Number of scatter-gather addr+len pairs after
	 * physical and DMA remapping hardware coalescing is performed.
	 * This is the number of scatter-gather entries the driver
	 * will actually have to deal with after DMA mapping is done.
	 */
	unsigned short nr_hw_segments;

	int tag;
	char *buffer;

	int ref_count;
	request_queue_t *q;
	struct request_list *rl;

	struct completion *waiting;
	void *special;

	/*
	 * when request is used as a packet command carrier
	 */
	unsigned int cmd_len;
	unsigned char cmd[BLK_MAX_CDB];

	unsigned int data_len;
	void *data;

	unsigned int sense_len;
	void *sense;

	unsigned int timeout;

	/*
	 * For Power Management requests
	 */
	struct request_pm_state *pm;

	/*
	 * completion callback. end_io_data should be folded in with waiting
	 */
	rq_end_io_fn *end_io;
	void *end_io_data;
};

/*
 * first three bits match BIO_RW* bits, important
 */
enum rq_flag_bits {
	__REQ_RW,		/* not set, read. set, write */
	__REQ_FAILFAST,		/* no low level driver retries */
	__REQ_SOFTBARRIER,	/* may not be passed by ioscheduler */
	__REQ_HARDBARRIER,	/* may not be passed by drive either */
	__REQ_CMD,		/* is a regular fs rw request */
	__REQ_NOMERGE,		/* don't touch this for merging */
	__REQ_STARTED,		/* drive already may have started this one */
	__REQ_DONTPREP,		/* don't call prep for this one */
	__REQ_QUEUED,		/* uses queueing */
	/*
	 * for ATA/ATAPI devices
	 */
	__REQ_PC,		/* packet command (special) */
	__REQ_BLOCK_PC,		/* queued down pc from block layer */
	__REQ_SENSE,		/* sense retrival */

	__REQ_FAILED,		/* set if the request failed */
	__REQ_QUIET,		/* don't worry about errors */
	__REQ_SPECIAL,		/* driver suplied command */
	__REQ_DRIVE_CMD,
	__REQ_DRIVE_TASK,
	__REQ_DRIVE_TASKFILE,
	__REQ_PREEMPT,		/* set for "ide_preempt" requests */
	__REQ_PM_SUSPEND,	/* suspend request */
	__REQ_PM_RESUME,	/* resume request */
	__REQ_PM_SHUTDOWN,	/* shutdown request */
	__REQ_BAR_PREFLUSH,	/* barrier pre-flush done */
	__REQ_BAR_POSTFLUSH,	/* barrier post-flush */
	__REQ_BAR_FLUSH,	/* rq is the flush request */
	__REQ_NR_BITS,		/* stops here */
};

#define REQ_RW		(1 << __REQ_RW)
#define REQ_FAILFAST	(1 << __REQ_FAILFAST)
#define REQ_SOFTBARRIER	(1 << __REQ_SOFTBARRIER)
#define REQ_HARDBARRIER	(1 << __REQ_HARDBARRIER)
#define REQ_CMD		(1 << __REQ_CMD)
#define REQ_NOMERGE	(1 << __REQ_NOMERGE)
#define REQ_STARTED	(1 << __REQ_STARTED)
#define REQ_DONTPREP	(1 << __REQ_DONTPREP)
#define REQ_QUEUED	(1 << __REQ_QUEUED)
#define REQ_PC		(1 << __REQ_PC)
#define REQ_BLOCK_PC	(1 << __REQ_BLOCK_PC)
#define REQ_SENSE	(1 << __REQ_SENSE)
#define REQ_FAILED	(1 << __REQ_FAILED)
#define REQ_QUIET	(1 << __REQ_QUIET)
#define REQ_SPECIAL	(1 << __REQ_SPECIAL)
#define REQ_DRIVE_CMD	(1 << __REQ_DRIVE_CMD)
#define REQ_DRIVE_TASK	(1 << __REQ_DRIVE_TASK)
#define REQ_DRIVE_TASKFILE	(1 << __REQ_DRIVE_TASKFILE)
#define REQ_PREEMPT	(1 << __REQ_PREEMPT)
#define REQ_PM_SUSPEND	(1 << __REQ_PM_SUSPEND)
#define REQ_PM_RESUME	(1 << __REQ_PM_RESUME)
#define REQ_PM_SHUTDOWN	(1 << __REQ_PM_SHUTDOWN)
#define REQ_BAR_PREFLUSH	(1 << __REQ_BAR_PREFLUSH)
#define REQ_BAR_POSTFLUSH	(1 << __REQ_BAR_POSTFLUSH)
#define REQ_BAR_FLUSH	(1 << __REQ_BAR_FLUSH)

/*
 * State information carried for REQ_PM_SUSPEND and REQ_PM_RESUME
 * requests. Some step values could eventually be made generic.
 */
struct request_pm_state
{
	/* PM state machine step value, currently driver specific */
	int	pm_step;
	/* requested PM state value (S1, S2, S3, S4, ...) */
	u32	pm_state;
	void*	data;		/* for driver use */
};

#include <linux/elevator.h>

typedef int (merge_request_fn) (request_queue_t *, struct request *,
				struct bio *);
typedef int (merge_requests_fn) (request_queue_t *, struct request *,
				 struct request *);
typedef void (request_fn_proc) (request_queue_t *q);
typedef int (make_request_fn) (request_queue_t *q, struct bio *bio);
typedef int (prep_rq_fn) (request_queue_t *, struct request *);
typedef void (unplug_fn) (request_queue_t *);

struct bio_vec;
typedef int (merge_bvec_fn) (request_queue_t *, struct bio *, struct bio_vec *);
typedef void (activity_fn) (void *data, int rw);
typedef int (issue_flush_fn) (request_queue_t *, struct gendisk *, sector_t *);
typedef int (prepare_flush_fn) (request_queue_t *, struct request *);
typedef void (end_flush_fn) (request_queue_t *, struct request *);

enum blk_queue_state {
	Queue_down,
	Queue_up,
};

struct blk_queue_tag {
	struct request **tag_index;	/* map of busy tags */
	unsigned long *tag_map;		/* bit map of free/busy tags */
	struct list_head busy_list;	/* fifo list of busy tags */
	int busy;			/* current depth */
	int max_depth;			/* what we will send to device */
	int real_max_depth;		/* what the array can hold */
	atomic_t refcnt;		/* map can be shared */
};

struct request_queue
{
	/*
	 * Together with queue_head for cacheline sharing
	 */
	struct list_head	queue_head;
	struct request		*last_merge;
	elevator_t		*elevator;

	/*
	 * the queue request freelist, one for reads and one for writes
	 */
	struct request_list	rq;

	request_fn_proc		*request_fn;
	merge_request_fn	*back_merge_fn;
	merge_request_fn	*front_merge_fn;
	merge_requests_fn	*merge_requests_fn;
	make_request_fn		*make_request_fn;
	prep_rq_fn		*prep_rq_fn;
	unplug_fn		*unplug_fn;
	merge_bvec_fn		*merge_bvec_fn;
	activity_fn		*activity_fn;
	issue_flush_fn		*issue_flush_fn;
	prepare_flush_fn	*prepare_flush_fn;
	end_flush_fn		*end_flush_fn;

	/*
	 * Auto-unplugging state
	 */
	struct timer_list	unplug_timer;
	int			unplug_thresh;	/* After this many requests */
	unsigned long		unplug_delay;	/* After this many jiffies */
	struct work_struct	unplug_work;

	struct backing_dev_info	backing_dev_info;

	/*
	 * The queue owner gets to use this for whatever they like.
	 * ll_rw_blk doesn't touch it.
	 */
	void			*queuedata;

	void			*activity_data;

	/*
	 * queue needs bounce pages for pages above this limit
	 */
	unsigned long		bounce_pfn;
	unsigned int		bounce_gfp;

	/*
	 * various queue flags, see QUEUE_* below
	 */
	unsigned long		queue_flags;

	/*
	 * protects queue structures from reentrancy. ->__queue_lock should
	 * _never_ be used directly, it is queue private. always use
	 * ->queue_lock.
	 */
	spinlock_t		__queue_lock;
	spinlock_t		*queue_lock;

	/*
	 * queue kobject
	 */
	struct kobject kobj;

	/*
	 * queue settings
	 */
	unsigned long		nr_requests;	/* Max # of requests */
	unsigned int		nr_congestion_on;
	unsigned int		nr_congestion_off;
	unsigned int		nr_batching;

	unsigned short		max_sectors;