include/linux/blkdev.h

#ifndef _LINUX_BLKDEV_H
#define _LINUX_BLKDEV_H

#include <linux/sched.h>

#ifdef CONFIG_BLOCK

#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/stringify.h>
#include <linux/gfp.h>
#include <linux/bsg.h>
#include <linux/smp.h>

#include <asm/scatterlist.h>

struct module;
struct scsi_ioctl_command;

struct request_queue;
struct elevator_queue;
struct request_pm_state;
struct blk_trace;
struct request;
struct sg_io_hdr;
struct bsg_job;

#define BLKDEV_MIN_RQ	4
#define BLKDEV_MAX_RQ	128	

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

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

enum rq_cmd_type_bits {
	REQ_TYPE_FS		= 1,	
	REQ_TYPE_BLOCK_PC,		
	REQ_TYPE_SENSE,			
	REQ_TYPE_PM_SUSPEND,		
	REQ_TYPE_PM_RESUME,		
	REQ_TYPE_PM_SHUTDOWN,		
	REQ_TYPE_SPECIAL,		
	REQ_TYPE_ATA_TASKFILE,
	REQ_TYPE_ATA_PC,
};

#define BLK_MAX_CDB	16

struct request {
	struct list_head queuelist;
	struct call_single_data csd;

	struct request_queue *q;

	unsigned int cmd_flags;
	enum rq_cmd_type_bits cmd_type;
	unsigned long atomic_flags;

	int cpu;

	
	unsigned int __data_len;	
	sector_t __sector;		

	struct bio *bio;
	struct bio *biotail;

	struct hlist_node hash;	
	union {
		struct rb_node rb_node;	
		void *completion_data;
	};

	union {
		struct {
			struct io_cq		*icq;
			void			*priv[2];
		} elv;

		struct {
			unsigned int		seq;
			struct list_head	list;
			rq_end_io_fn		*saved_end_io;
		} flush;
	};

	struct gendisk *rq_disk;
	struct hd_struct *part;
	unsigned long start_time;
#ifdef CONFIG_BLK_CGROUP
	unsigned long long start_time_ns;
	unsigned long long io_start_time_ns;    
#endif
	unsigned short nr_phys_segments;
#if defined(CONFIG_BLK_DEV_INTEGRITY)
	unsigned short nr_integrity_segments;
#endif

	unsigned short ioprio;

	int ref_count;

	void *special;		
	char *buffer;		

	int tag;
	int errors;

	unsigned char __cmd[BLK_MAX_CDB];
	unsigned char *cmd;
	unsigned short cmd_len;

	unsigned int extra_len;	
	unsigned int sense_len;
	unsigned int resid_len;	
	void *sense;

	unsigned long deadline;
	struct list_head timeout_list;
	unsigned int timeout;
	int retries;

	rq_end_io_fn *end_io;
	void *end_io_data;

	
	struct request *next_rq;
};

static inline unsigned short req_get_ioprio(struct request *req)
{
	return req->ioprio;
}

struct request_pm_state
{
	
	int	pm_step;
	
	u32	pm_state;
	void*	data;		
};

#include <linux/elevator.h>

typedef void (request_fn_proc) (struct request_queue *q);
typedef void (make_request_fn) (struct request_queue *q, struct bio *bio);
typedef int (prep_rq_fn) (struct request_queue *, struct request *);
typedef void (unprep_rq_fn) (struct request_queue *, struct request *);

struct bio_vec;
struct bvec_merge_data {
	struct block_device *bi_bdev;
	sector_t bi_sector;
	unsigned bi_size;
	unsigned long bi_rw;
};
typedef int (merge_bvec_fn) (struct request_queue *, struct bvec_merge_data *,
			     struct bio_vec *);
typedef void (softirq_done_fn)(struct request *);
typedef int (dma_drain_needed_fn)(struct request *);
typedef int (lld_busy_fn) (struct request_queue *q);
typedef int (bsg_job_fn) (struct bsg_job *);

enum blk_eh_timer_return {
	BLK_EH_NOT_HANDLED,
	BLK_EH_HANDLED,
	BLK_EH_RESET_TIMER,
};

typedef enum blk_eh_timer_return (rq_timed_out_fn)(struct request *);

enum blk_queue_state {
	Queue_down,
	Queue_up,
};

struct blk_queue_tag {
	struct request **tag_index;	
	unsigned long *tag_map;		
	int busy;			
	int max_depth;			
	int real_max_depth;		
	atomic_t refcnt;		
};

#define BLK_SCSI_MAX_CMDS	(256)
#define BLK_SCSI_CMD_PER_LONG	(BLK_SCSI_MAX_CMDS / (sizeof(long) * 8))

struct queue_limits {
	unsigned long		bounce_pfn;
	unsigned long		seg_boundary_mask;

	unsigned int		max_hw_sectors;
	unsigned int		max_sectors;
	unsigned int		max_segment_size;
	unsigned int		physical_block_size;
	unsigned int		alignment_offset;
	unsigned int		io_min;
	unsigned int		io_opt;
	unsigned int		max_discard_sectors;
	unsigned int		discard_granularity;
	unsigned int		discard_alignment;

	unsigned short		logical_block_size;
	unsigned short		max_segments;
	unsigned short		max_integrity_segments;

	unsigned char		misaligned;
	unsigned char		discard_misaligned;
	unsigned char		cluster;
	unsigned char		discard_zeroes_data;
};

struct request_queue {
	struct list_head	queue_head;
	struct request		*last_merge;
	struct elevator_queue	*elevator;

	struct request_list	rq;

	request_fn_proc		*request_fn;
	make_request_fn		*make_request_fn;
	prep_rq_fn		*prep_rq_fn;
	unprep_rq_fn		*unprep_rq_fn;
	merge_bvec_fn		*merge_bvec_fn;
	softirq_done_fn		*softirq_done_fn;
	rq_timed_out_fn		*rq_timed_out_fn;
	dma_drain_needed_fn	*dma_drain_needed;
	lld_busy_fn		*lld_busy_fn;

	sector_t		end_sector;
	struct request		*boundary_rq;

	struct delayed_work	delay_work;

	struct backing_dev_info	backing_dev_info;

	void			*queuedata;

	unsigned long		queue_flags;

	int			id;

	gfp_t			bounce_gfp;

	spinlock_t		__queue_lock;
	spinlock_t		*queue_lock;

	struct kobject kobj;

	unsigned long		nr_requests;	
	unsigned int		nr_congestion_on;
	unsigned int		nr_congestion_off;
	unsigned int		nr_batching;

	unsigned int		dma_drain_size;
	void			*dma_drain_buffer;
	unsigned int		dma_pad_mask;
	unsigned int		dma_alignment;

	struct blk_queue_tag	*queue_tags;
	struct list_head	tag_busy_list;

	unsigned int		nr_sorted;
	unsigned int		in_flight[2];

	unsigned int		rq_timeout;
	struct timer_list	timeout;
	struct list_head	timeout_list;

	struct list_head	icq_list;

	struct queue_limits	limits;

	unsigned int		sg_timeout;
	unsigned int		sg_reserved_size;
	int			node;
#ifdef CONFIG_BLK_DEV_IO_TRACE
	struct blk_trace	*blk_trace;
#endif
	unsigned int		flush_flags;
	unsigned int		flush_not_queueable:1;
	unsigned int		flush_queue_delayed:1;
	unsigned int		flush_pending_idx:1;
	unsigned int		flush_running_idx:1;
	unsigned long		flush_pending_since;
	struct list_head	flush_queue[2];
	struct list_head	flush_data_in_flight;
	struct request		flush_rq;

	struct mutex		sysfs_lock;

#if defined(CONFIG_BLK_DEV_BSG)
	bsg_job_fn		*bsg_job_fn;
	int			bsg_job_size;
	struct bsg_class_device bsg_dev;
#endif

#ifdef CONFIG_BLK_DEV_THROTTLING
	
	struct throtl_data *td;
#endif
};

#define QUEUE_FLAG_QUEUED	1	
#define QUEUE_FLAG_STOPPED	2	
#define	QUEUE_FLAG_SYNCFULL	3	
#define QUEUE_FLAG_ASYNCFULL	4	
#define QUEUE_FLAG_DEAD		5	
#define QUEUE_FLAG_ELVSWITCH	6	
#define QUEUE_FLAG_BIDI		7	
#define QUEUE_FLAG_NOMERGES     8	
#define QUEUE_FLAG_SAME_COMP	9	
#define QUEUE_FLAG_FAIL_IO     10	
#define QUEUE_FLAG_STACKABLE   11	
#define QUEUE_FLAG_NONROT      12	
#define QUEUE_FLAG_VIRT        QUEUE_FLAG_NONROT 
#define QUEUE_FLAG_IO_STAT     13	
#define QUEUE_FLAG_DISCARD     14	
#define QUEUE_FLAG_NOXMERGES   15	
#define QUEUE_FLAG_ADD_RANDOM  16	
#define QUEUE_FLAG_SECDISCARD  17	
#define QUEUE_FLAG_SAME_FORCE  18	
#define QUEUE_FLAG_SANITIZE    19	

#define QUEUE_FLAG_DEFAULT	((1 << QUEUE_FLAG_IO_STAT) |		\
				 (1 << QUEUE_FLAG_STACKABLE)	|	\
				 (1 << QUEUE_FLAG_SAME_COMP)	|	\
				 (1 << QUEUE_FLAG_ADD_RANDOM))

static inline void queue_lockdep_assert_held(struct request_queue *q)
{
	if (q->queue_lock)
		lockdep_assert_held(q->queue_lock);
}

static inline void queue_flag_set_unlocked(unsigned int flag,
					   struct request_queue *q)
{
	__set_bit(flag, &q->queue_flags);
}

static inline int queue_flag_test_and_clear(unsigned int flag,
					    struct request_queue *q)
{
	queue_lockdep_assert_held(q);

	if (test_bit(flag, &q->queue_flags)) {
		__clear_bit(flag, &q->queue_flags);
		return 1;
	}

	return 0;
}

static inline int queue_flag_test_and_set(unsigned int flag,
					  struct request_queue *q)
{
	queue_lockdep_assert_held(q);

	if (!test_bit(flag, &q->queue_flags)) {
		__set_bit(flag, &q->queue_flags);
		return 0;
	}

	return 1;
}

static inline void queue_flag_set(unsigned int flag, struct request_queue *q)
{
	queue_lockdep_assert_held(q);
	__set_bit(flag, &q->queue_flags);
}

static inline void queue_flag_clear_unlocked(unsigned int flag,
					     struct request_queue *q)
{
	__clear_bit(flag, &q->queue_flags);
}

static inline int queue_in_flight(struct request_queue *q)
{
	return q->in_flight[0] + q->in_flight[1];
}

static inline void queue_flag_clear(unsigned int flag, struct request_queue *q)
{
	queue_lockdep_assert_held(q);
	__clear_bit(flag, &q->queue_flags);
}

#define blk_queue_tagged(q)	test_bit(QUEUE_FLAG_QUEUED, &(q)->queue_flags)
#define blk_queue_stopped(q)	test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
#define blk_queue_dead(q)	test_bit(QUEUE_FLAG_DEAD, &(q)->queue_flags)
#define blk_queue_nomerges(q)	test_bit(QUEUE_FLAG_NOMERGES, &(q)->queue_flags)
#define blk_queue_noxmerges(q)	\
	test_bit(QUEUE_FLAG_NOXMERGES, &(q)->queue_flags)
#define blk_queue_nonrot(q)	test_bit(QUEUE_FLAG_NONROT, &(q)->queue_flags)
#define blk_queue_io_stat(q)	test_bit(QUEUE_FLAG_IO_STAT, &(q)->queue_flags)
#define blk_queue_add_random(q)	test_bit(QUEUE_FLAG_ADD_RANDOM, &(q)->queue_flags)
#define blk_queue_stackable(q)	\
	test_bit(QUEUE_FLAG_STACKABLE, &(q)->queue_flags)
#define blk_queue_discard(q)	test_bit(QUEUE_FLAG_DISCARD, &(q)->queue_flags)
#define blk_queue_sanitize(q)	test_bit(QUEUE_FLAG_SANITIZE, &(q)->queue_flags)
#define blk_queue_secdiscard(q)	(blk_queue_discard(q) && \
	test_bit(QUEUE_FLAG_SECDISCARD, &(q)->queue_flags))

#define blk_noretry_request(rq) \
	((rq)->cmd_flags & (REQ_FAILFAST_DEV|REQ_FAILFAST_TRANSPORT| \
			     REQ_FAILFAST_DRIVER))

#define blk_account_rq(rq) \
	(((rq)->cmd_flags & REQ_STARTED) && \
	 ((rq)->cmd_type == REQ_TYPE_FS || \
	  ((rq)->cmd_flags & REQ_DISCARD)))

#define blk_pm_request(rq)	\
	((rq)->cmd_type == REQ_TYPE_PM_SUSPEND || \
	 (rq)->cmd_type == REQ_TYPE_PM_RESUME)

#define blk_rq_cpu_valid(rq)	((rq)->cpu != -1)
#define blk_bidi_rq(rq)		((rq)->next_rq != NULL)
#define blk_queued_rq(rq)	(!list_empty(&(rq)->queuelist))

#define list_entry_rq(ptr)	list_entry((ptr), struct request, queuelist)

#define rq_data_dir(rq)		((rq)->cmd_flags & 1)

static inline unsigned int blk_queue_cluster(struct request_queue *q)
{
	return q->limits.cluster;
}

static inline bool rw_is_sync(unsigned int rw_flags)
{
	return !(rw_flags & REQ_WRITE) || (rw_flags & REQ_SYNC);
}

static inline bool rq_is_sync(struct request *rq)
{
	return rw_is_sync(rq->cmd_flags);
}

static inline int blk_queue_full(struct request_queue *q, int sync)
{
	if (sync)
		return test_bit(QUEUE_FLAG_SYNCFULL, &q->queue_flags);
	return test_bit(QUEUE_FLAG_ASYNCFULL, &q->queue_flags);
}

static inline void blk_set_queue_full(struct request_queue *q, int sync)
{
	if (sync)
		queue_flag_set(QUEUE_FLAG_SYNCFULL, q);
	else
		queue_flag_set(QUEUE_FLAG_ASYNCFULL, q);
}

static inline void blk_clear_queue_full(struct request_queue *q, int sync)
{
	if (sync)
		queue_flag_clear(QUEUE_FLAG_SYNCFULL, q);
	else
		queue_flag_clear(QUEUE_FLAG_ASYNCFULL, q);
}


#define RQ_NOMERGE_FLAGS	\
	(REQ_NOMERGE | REQ_STARTED | REQ_SOFTBARRIER | REQ_FLUSH | REQ_FUA)
#define rq_mergeable(rq)	\
	(!((rq)->cmd_flags & RQ_NOMERGE_FLAGS) && \
	 (((rq)->cmd_flags & REQ_DISCARD) || \
	  (rq)->cmd_type == REQ_TYPE_FS))

#define BLKPREP_OK		0	
#define BLKPREP_KILL		1	
#define BLKPREP_DEFER		2	

extern unsigned long blk_max_low_pfn, blk_max_pfn;


#if BITS_PER_LONG == 32
#define BLK_BOUNCE_HIGH		((u64)blk_max_low_pfn << PAGE_SHIFT)
#else
#define BLK_BOUNCE_HIGH		-1ULL
#endif
#define BLK_BOUNCE_ANY		(-1ULL)
#define BLK_BOUNCE_ISA		(DMA_BIT_MASK(24))

#define BLK_DEFAULT_SG_TIMEOUT	(60 * HZ)
#define BLK_MIN_SG_TIMEOUT	(7 * HZ)

#ifdef CONFIG_BOUNCE
extern int init_emergency_isa_pool(void);
extern void blk_queue_bounce(struct request_queue *q, struct bio **bio);
#else
static inline int init_emergency_isa_pool(void)
{
	return 0;
}
static inline void blk_queue_bounce(struct request_queue *q, struct bio **bio)
{
}
#endif 

struct rq_map_data {
	struct page **pages;
	int page_order;
	int nr_entries;
	unsigned long offset;
	int null_mapped;
	int from_user;
};

struct req_iterator {
	int i;
	struct bio *bio;
};

#define for_each_bio(_bio)		\
	for (; _bio; _bio = _bio->bi_next)
#define __rq_for_each_bio(_bio, rq)	\
	if ((rq->bio))			\
		for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)

#define rq_for_each_segment(bvl, _rq, _iter)			\
	__rq_for_each_bio(_iter.bio, _rq)			\
		bio_for_each_segment(bvl, _iter.bio, _iter.i)

#define rq_iter_last(rq, _iter)					\
		(_iter.bio->bi_next == NULL && _iter.i == _iter.bio->bi_vcnt-1)

#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
# error	"You should define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform"
#endif
#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
extern void rq_flush_dcache_pages(struct request *rq);
#else
static inline void rq_flush_dcache_pages(struct request *rq)
{
}
#endif

extern int blk_register_queue(struct gendisk *disk);
extern void blk_unregister_queue(struct gendisk *disk);
extern void generic_make_request(struct bio *bio);
extern void blk_rq_init(struct request_queue *q, struct request *rq);
extern void blk_put_request(struct request *);
extern void __blk_put_request(struct request_queue *, struct request *);
extern struct request *blk_get_request(struct request_queue *, int, gfp_t);
extern struct request *blk_make_request(struct request_queue *, struct bio *,
					gfp_t);
extern void blk_requeue_request(struct request_queue *, struct request *);
extern void blk_add_request_payload(struct request *rq, struct page *page,
		unsigned int len);
extern int blk_rq_check_limits(struct request_queue *q, struct request *rq);
extern int blk_lld_busy(struct request_queue *q);
extern int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
			     struct bio_set *bs, gfp_t gfp_mask,
			     int (*bio_ctr)(struct bio *, struct bio *, void *),
			     void *data);
extern void blk_rq_unprep_clone(struct request *rq);
extern int blk_insert_cloned_request(struct request_queue *q,
				     struct request *rq);
extern void blk_delay_queue(struct request_queue *, unsigned long);
extern void blk_recount_segments(struct request_queue *, struct bio *);
extern int scsi_verify_blk_ioctl(struct block_device *, unsigned int);
extern int scsi_cmd_blk_ioctl(struct block_device *, fmode_t,
			      unsigned int, void __user *);
extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t,
			  unsigned int, void __user *);
extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t,
			 struct scsi_ioctl_command __user *);

extern void blk_queue_bio(struct request_queue *q, struct bio *bio);

static inline void blk_clear_queue_congested(struct request_queue *q, int sync)
{
	clear_bdi_congested(&q->backing_dev_info, sync);
}

static inline void blk_set_queue_congested(struct request_queue *q, int sync)
{
	set_bdi_congested(&q->backing_dev_info, sync);
}

extern void blk_start_queue(struct request_queue *q);
extern void blk_stop_queue(struct request_queue *q);
extern void blk_sync_queue(struct request_queue *q);
extern void __blk_stop_queue(struct request_queue *q);
extern void __blk_run_queue(struct request_queue *q);
extern void blk_run_queue(struct request_queue *);
extern void blk_run_queue_async(struct request_queue *q);
extern int blk_rq_map_user(struct request_queue *, struct request *,
			   struct rq_map_data *, void __user *, unsigned long,
			   gfp_t);
extern int blk_rq_unmap_user(struct bio *);
extern int blk_rq_map_kern(struct request_queue *, struct request *, void *, unsigned int, gfp_t);
extern int blk_rq_map_user_iov(struct request_queue *, struct request *,
			       struct rq_map_data *, struct sg_iovec *, int,
			       unsigned int, gfp_t);
extern int blk_execute_rq(struct request_queue *, struct gendisk *,
			  struct request *, int);
extern void blk_execute_rq_nowait(struct request_queue *, struct gendisk *,
				  struct request *, int, rq_end_io_fn *);

static inline struct request_queue *bdev_get_queue(struct block_device *bdev)
{
	return bdev->bd_disk->queue;
}

static inline sector_t blk_rq_pos(const struct request *rq)
{
	return rq->__sector;
}

static inline unsigned int blk_rq_bytes(const struct request *rq)
{
	return rq->__data_len;
}

static inline int blk_rq_cur_bytes(const struct request *rq)
{
	return rq->bio ? bio_cur_bytes(rq->bio) : 0;
}

extern unsigned int blk_rq_err_bytes(const struct request *rq);

static inline unsigned int blk_rq_sectors(const struct request *rq)
{
	return blk_rq_bytes(rq) >> 9;
}

static inline unsigned int blk_rq_cur_sectors(const struct request *rq)
{
	return blk_rq_cur_bytes(rq) >> 9;
}

extern struct request *blk_peek_request(struct request_queue *q);
extern void blk_start_request(struct request *rq);
extern struct request *blk_fetch_request(struct request_queue *q);

extern bool blk_update_request(struct request *rq, int error,
			       unsigned int nr_bytes);
extern bool blk_end_request(struct request *rq, int error,
			    unsigned int nr_bytes);
extern void blk_end_request_all(struct request *rq, int error);
extern bool blk_end_request_cur(struct request *rq, int error);
extern bool blk_end_request_err(struct request *rq, int error);
extern bool __blk_end_request(struct request *rq, int error,
			      unsigned int nr_bytes);
extern void __blk_end_request_all(struct request *rq, int error);
extern bool __blk_end_request_cur(struct request *rq, int error);
extern bool __blk_end_request_err(struct request *rq, int error);

extern void blk_complete_request(struct request *);
extern void __blk_complete_request(struct request *);
extern void blk_abort_request(struct request *);
extern void blk_abort_queue(struct request_queue *);
extern void blk_unprep_request(struct request *);

extern struct request_queue *blk_init_queue_node(request_fn_proc *rfn,
					spinlock_t *lock, int node_id);
extern struct request_queue *blk_init_queue(request_fn_proc *, spinlock_t *);
extern struct request_queue *blk_init_allocated_queue(struct request_queue *,
						      request_fn_proc *, spinlock_t *);
extern void blk_cleanup_queue(struct request_queue *);
extern void blk_queue_make_request(struct request_queue *, make_request_fn *);
extern void blk_queue_bounce_limit(struct request_queue *, u64);
extern void blk_limits_max_hw_sectors(struct queue_limits *, unsigned int);
extern void blk_queue_max_hw_sectors(struct request_queue *, unsigned int);
extern void blk_queue_max_segments(struct request_queue *, unsigned short);
extern void blk_queue_max_segment_size(struct request_queue *, unsigned int);
extern void blk_queue_max_discard_sectors(struct request_queue *q,
		unsigned int max_discard_sectors);
extern void blk_queue_logical_block_size(struct request_queue *, unsigned short);
extern void blk_queue_physical_block_size(struct request_queue *, unsigned int);
extern void blk_queue_alignment_offset(struct request_queue *q,
				       unsigned int alignment);
extern void blk_limits_io_min(struct queue_limits *limits, unsigned int min);
extern void blk_queue_io_min(struct request_queue *q, unsigned int min);
extern void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt);
extern void blk_queue_io_opt(struct request_queue *q, unsigned int opt);
extern void blk_set_default_limits(struct queue_limits *lim);
extern void blk_set_stacking_limits(struct queue_limits *lim);
extern int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
			    sector_t offset);
extern int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev,
			    sector_t offset);
extern void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
			      sector_t offset);
extern void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b);
extern void blk_queue_dma_pad(struct request_queue *, unsigned int);
extern void blk_queue_update_dma_pad(struct request_queue *, unsigned int);
extern int blk_queue_dma_drain(struct request_queue *q,
			       dma_drain_needed_fn *dma_drain_needed,
			       void *buf, unsigned int size);
extern void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn);
extern void blk_queue_segment_boundary(struct request_queue *, unsigned long);
extern void blk_queue_prep_rq(struct request_queue *, prep_rq_fn *pfn);
extern void blk_queue_unprep_rq(struct request_queue *, unprep_rq_fn *ufn);
extern void blk_queue_merge_bvec(struct request_queue *, merge_bvec_fn *);
extern void blk_queue_dma_alignment(struct request_queue *, int);
extern void blk_queue_update_dma_alignment(struct request_queue *, int);
extern void blk_queue_softirq_done(struct request_queue *, softirq_done_fn *);
extern void blk_queue_rq_timed_out(struct request_queue *, rq_timed_out_fn *);
extern void blk_queue_rq_timeout(struct request_queue *, unsigned int);
extern void blk_queue_flush(struct request_queue *q, unsigned int flush);
extern void blk_queue_flush_queueable(struct request_queue *q, bool queueable);
extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);

extern int blk_rq_map_sg(struct request_queue *, struct request *, struct scatterlist *);
extern void blk_dump_rq_flags(struct request *, char *);
extern long nr_blockdev_pages(void);

bool __must_check blk_get_queue(struct request_queue *);
struct request_queue *blk_alloc_queue(gfp_t);
struct request_queue *blk_alloc_queue_node(gfp_t, int);
extern void blk_put_queue(struct request_queue *);

struct blk_plug {
	unsigned long magic; 
	struct list_head list; 
	struct list_head cb_list; 
	unsigned int should_sort; 
};
#define BLK_MAX_REQUEST_COUNT 16

struct blk_plug_cb {
	struct list_head list;
	void (*callback)(struct blk_plug_cb *);
};

extern void blk_start_plug(struct blk_plug *);
extern void blk_finish_plug(struct blk_plug *);
extern void blk_flush_plug_list(struct blk_plug *, bool);

static inline void blk_flush_plug(struct task_struct *tsk)
{
	struct blk_plug *plug = tsk->plug;

	if (plug)
		blk_flush_plug_list(plug, false);
}

static inline void blk_schedule_flush_plug(struct task_struct *tsk)
{
	struct blk_plug *plug = tsk->plug;

	if (plug)
		blk_flush_plug_list(plug, true);
}

static inline bool blk_needs_flush_plug(struct task_struct *tsk)
{
	struct blk_plug *plug = tsk->plug;

	return plug && (!list_empty(&plug->list) || !list_empty(&plug->cb_list));
}

#define blk_rq_tagged(rq)		((rq)->cmd_flags & REQ_QUEUED)
extern int blk_queue_start_tag(struct request_queue *, struct request *);
extern struct request *blk_queue_find_tag(struct request_queue *, int);
extern void blk_queue_end_tag(struct request_queue *, struct request *);
extern int blk_queue_init_tags(struct request_queue *, int, struct blk_queue_tag *);
extern void blk_queue_free_tags(struct request_queue *);
extern int blk_queue_resize_tags(struct request_queue *, int);
extern void blk_queue_invalidate_tags(struct request_queue *);
extern struct blk_queue_tag *blk_init_tags(int);
extern void blk_free_tags(struct blk_queue_tag *);

static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
						int tag)
{
	if (unlikely(bqt == NULL || tag >= bqt->real_max_depth))
		return NULL;
	return bqt->tag_index[tag];
}

#define BLKDEV_DISCARD_SECURE  0x01    

extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *);
extern int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
		sector_t nr_sects, gfp_t gfp_mask, unsigned long flags);
extern int blkdev_issue_sanitize(struct block_device *bdev, gfp_t gfp_mask);
extern int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
			sector_t nr_sects, gfp_t gfp_mask);
static inline int sb_issue_discard(struct super_block *sb, sector_t block,
		sector_t nr_blocks, gfp_t gfp_mask, unsigned long flags)
{
	return blkdev_issue_discard(sb->s_bdev, block << (sb->s_blocksize_bits - 9),
				    nr_blocks << (sb->s_blocksize_bits - 9),
				    gfp_mask, flags);
}
static inline int sb_issue_zeroout(struct super_block *sb, sector_t block,
		sector_t nr_blocks, gfp_t gfp_mask)
{
	return blkdev_issue_zeroout(sb->s_bdev,
				    block << (sb->s_blocksize_bits - 9),
				    nr_blocks << (sb->s_blocksize_bits - 9),
				    gfp_mask);
}

extern int blk_verify_command(unsigned char *cmd, fmode_t has_write_perm);

enum blk_default_limits {
	BLK_MAX_SEGMENTS	= 128,
	BLK_SAFE_MAX_SECTORS	= 255,
	BLK_DEF_MAX_SECTORS	= 4096,
	BLK_MAX_SEGMENT_SIZE	= 65536,
	BLK_SEG_BOUNDARY_MASK	= 0xFFFFFFFFUL,
};

#define blkdev_entry_to_request(entry) list_entry((entry), struct request, queuelist)

static inline unsigned long queue_bounce_pfn(struct request_queue *q)
{
	return q->limits.bounce_pfn;
}

static inline unsigned long queue_segment_boundary(struct request_queue *q)
{
	return q->limits.seg_boundary_mask;
}

static inline unsigned int queue_max_sectors(struct request_queue *q)
{
	return q->limits.max_sectors;
}

static inline unsigned int queue_max_hw_sectors(struct request_queue *q)
{
	return q->limits.max_hw_sectors;
}

static inline unsigned short queue_max_segments(struct request_queue *q)
{
	return q->limits.max_segments;
}

static inline unsigned int queue_max_segment_size(struct request_queue *q)
{
	return q->limits.max_segment_size;
}

static inline unsigned short queue_logical_block_size(struct request_queue *q)
{
	int retval = 512;

	if (q && q->limits.logical_block_size)
		retval = q->limits.logical_block_size;

	return retval;
}

static inline unsigned short bdev_logical_block_size(struct block_device *bdev)
{
	return queue_logical_block_size(bdev_get_queue(bdev));
}

static inline unsigned int queue_physical_block_size(struct request_queue *q)
{
	return q->limits.physical_block_size;
}

static inline unsigned int bdev_physical_block_size(struct block_device *bdev)
{
	return queue_physical_block_size(bdev_get_queue(bdev));
}

static inline unsigned int queue_io_min(struct request_queue *q)
{
	return q->limits.io_min;
}

static inline int bdev_io_min(struct block_device *bdev)
{
	return queue_io_min(bdev_get_queue(bdev));
}

static inline unsigned int queue_io_opt(struct request_queue *q)
{
	return q->limits.io_opt;
}

static inline int bdev_io_opt(struct block_device *bdev)
{
	return queue_io_opt(bdev_get_queue(bdev));
}

static inline int queue_alignment_offset(struct request_queue *q)
{
	if (q->limits.misaligned)
		return -1;

	return q->limits.alignment_offset;
}

static inline int queue_limit_alignment_offset(struct queue_limits *lim, sector_t sector)
{
	unsigned int granularity = max(lim->physical_block_size, lim->io_min);
	unsigned int alignment = (sector << 9) & (granularity - 1);

	return (granularity + lim->alignment_offset - alignment)
		& (granularity - 1);
}

static inline int bdev_alignment_offset(struct block_device *bdev)
{
	struct request_queue *q = bdev_get_queue(bdev);

	if (q->limits.misaligned)
		return -1;

	if (bdev != bdev->bd_contains)
		return bdev->bd_part->alignment_offset;

	return q->limits.alignment_offset;
}

static inline int queue_discard_alignment(struct request_queue *q)
{
	if (q->limits.discard_misaligned)
		return -1;

	return q->limits.discard_alignment;
}

static inline int queue_limit_discard_alignment(struct queue_limits *lim, sector_t sector)
{
	unsigned int alignment = (sector << 9) & (lim->discard_granularity - 1);

	if (!lim->max_discard_sectors)
		return 0;

	return (lim->discard_granularity + lim->discard_alignment - alignment)
		& (lim->discard_granularity - 1);
}

static inline unsigned int queue_discard_zeroes_data(struct request_queue *q)
{
	if (q->limits.max_discard_sectors && q->limits.discard_zeroes_data == 1)
		return 1;

	return 0;
}

static inline unsigned int bdev_discard_zeroes_data(struct block_device *bdev)
{
	return queue_discard_zeroes_data(bdev_get_queue(bdev));
}

static inline int queue_dma_alignment(struct request_queue *q)
{
	return q ? q->dma_alignment : 511;
}

static inline int blk_rq_aligned(struct request_queue *q, unsigned long addr,
				 unsigned int len)
{
	unsigned int alignment = queue_dma_alignment(q) | q->dma_pad_mask;
	return !(addr & alignment) && !(len & alignment);
}

static inline unsigned int blksize_bits(unsigned int size)
{
	unsigned int bits = 8;
	do {
		bits++;
		size >>= 1;
	} while (size > 256);
	return bits;
}

static inline unsigned int block_size(struct block_device *bdev)
{
	return bdev->bd_block_size;
}

static inline bool queue_flush_queueable(struct request_queue *q)
{
	return !q->flush_not_queueable;
}

typedef struct {struct page *v;} Sector;

unsigned char *read_dev_sector(struct block_device *, sector_t, Sector *);

static inline void put_dev_sector(Sector p)
{
	page_cache_release(p.v);
}

struct work_struct;
int kblockd_schedule_work(struct request_queue *q, struct work_struct *work);

#ifdef CONFIG_BLK_CGROUP
static inline void set_start_time_ns(struct request *req)
{
	preempt_disable();
	req->start_time_ns = sched_clock();
	preempt_enable();
}

static inline void set_io_start_time_ns(struct request *req)
{
	preempt_disable();
	req->io_start_time_ns = sched_clock();
	preempt_enable();
}

static inline uint64_t rq_start_time_ns(struct request *req)
{
        return req->start_time_ns;
}

static inline uint64_t rq_io_start_time_ns(struct request *req)
{
        return req->io_start_time_ns;
}
#else
static inline void set_start_time_ns(struct request *req) {}
static inline void set_io_start_time_ns(struct request *req) {}
static inline uint64_t rq_start_time_ns(struct request *req)
{
	return 0;
}
static inline uint64_t rq_io_start_time_ns(struct request *req)
{
	return 0;
}
#endif

#define MODULE_ALIAS_BLOCKDEV(major,minor) \
	MODULE_ALIAS("block-major-" __stringify(major) "-" __stringify(minor))
#define MODULE_ALIAS_BLOCKDEV_MAJOR(major) \
	MODULE_ALIAS("block-major-" __stringify(major) "-*")

#if defined(CONFIG_BLK_DEV_INTEGRITY)

#define INTEGRITY_FLAG_READ	2	
#define INTEGRITY_FLAG_WRITE	4	

struct blk_integrity_exchg {
	void			*prot_buf;
	void			*data_buf;
	sector_t		sector;
	unsigned int		data_size;
	unsigned short		sector_size;
	const char		*disk_name;
};

typedef void (integrity_gen_fn) (struct blk_integrity_exchg *);
typedef int (integrity_vrfy_fn) (struct blk_integrity_exchg *);
typedef void (integrity_set_tag_fn) (void *, void *, unsigned int);
typedef void (integrity_get_tag_fn) (void *, void *, unsigned int);

struct blk_integrity {
	integrity_gen_fn	*generate_fn;
	integrity_vrfy_fn	*verify_fn;
	integrity_set_tag_fn	*set_tag_fn;
	integrity_get_tag_fn	*get_tag_fn;

	unsigned short		flags;
	unsigned short		tuple_size;
	unsigned short		sector_size;
	unsigned short		tag_size;

	const char		*name;

	struct kobject		kobj;
};

extern bool blk_integrity_is_initialized(struct gendisk *);
extern int blk_integrity_register(struct gendisk *, struct blk_integrity *);
extern void blk_integrity_unregister(struct gendisk *);
extern int blk_integrity_compare(struct gendisk *, struct gendisk *);
extern int blk_rq_map_integrity_sg(struct request_queue *, struct bio *,
				   struct scatterlist *);
extern int blk_rq_count_integrity_sg(struct request_queue *, struct bio *);
extern int blk_integrity_merge_rq(struct request_queue *, struct request *,
				  struct request *);
extern int blk_integrity_merge_bio(struct request_queue *, struct request *,
				   struct bio *);

static inline
struct blk_integrity *bdev_get_integrity(struct block_device *bdev)
{
	return bdev->bd_disk->integrity;
}

static inline struct blk_integrity *blk_get_integrity(struct gendisk *disk)
{
	return disk->integrity;
}

static inline int blk_integrity_rq(struct request *rq)
{
	if (rq->bio == NULL)
		return 0;

	return bio_integrity(rq->bio);
}

static inline void blk_queue_max_integrity_segments(struct request_queue *q,
						    unsigned int segs)
{
	q->limits.max_integrity_segments = segs;
}

static inline unsigned short
queue_max_integrity_segments(struct request_queue *q)
{
	return q->limits.max_integrity_segments;
}

#else 

struct bio;
struct block_device;
struct gendisk;
struct blk_integrity;

static inline int blk_integrity_rq(struct request *rq)
{
	return 0;
}
static inline int blk_rq_count_integrity_sg(struct request_queue *q,
					    struct bio *b)
{
	return 0;
}
static inline int blk_rq_map_integrity_sg(struct request_queue *q,
					  struct bio *b,
					  struct scatterlist *s)
{
	return 0;
}
static inline struct blk_integrity *bdev_get_integrity(struct block_device *b)
{
	return 0;
}
static inline struct blk_integrity *blk_get_integrity(struct gendisk *disk)
{
	return NULL;
}
static inline int blk_integrity_compare(struct gendisk *a, struct gendisk *b)
{
	return 0;
}
static inline int blk_integrity_register(struct gendisk *d,
					 struct blk_integrity *b)
{
	return 0;
}
static inline void blk_integrity_unregister(struct gendisk *d)
{
}
static inline void blk_queue_max_integrity_segments(struct request_queue *q,
						    unsigned int segs)
{
}
static inline unsigned short queue_max_integrity_segments(struct request_queue *q)
{
	return 0;
}
static inline int blk_integrity_merge_rq(struct request_queue *rq,
					 struct request *r1,
					 struct request *r2)
{
	return 0;
}
static inline int blk_integrity_merge_bio(struct request_queue *rq,
					  struct request *r,
					  struct bio *b)
{
	return 0;
}
static inline bool blk_integrity_is_initialized(struct gendisk *g)
{
	return 0;
}

#endif 

struct block_device_operations {
	int (*open) (struct block_device *, fmode_t);
	int (*release) (struct gendisk *, fmode_t);
	int (*ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
	int (*compat_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
	int (*direct_access) (struct block_device *, sector_t,
						void **, unsigned long *);
	unsigned int (*check_events) (struct gendisk *disk,
				      unsigned int clearing);
	
	int (*media_changed) (struct gendisk *);
	void (*unlock_native_capacity) (struct gendisk *);
	int (*revalidate_disk) (struct gendisk *);
	int (*getgeo)(struct block_device *, struct hd_geometry *);
	
	void (*swap_slot_free_notify) (struct block_device *, unsigned long);
	struct module *owner;
};

extern int __blkdev_driver_ioctl(struct block_device *, fmode_t, unsigned int,
				 unsigned long);
#else 
#define buffer_heads_over_limit 0

static inline long nr_blockdev_pages(void)
{
	return 0;
}

struct blk_plug {
};

static inline void blk_start_plug(struct blk_plug *plug)
{
}

static inline void blk_finish_plug(struct blk_plug *plug)
{
}

static inline void blk_flush_plug(struct task_struct *task)
{
}

static inline void blk_schedule_flush_plug(struct task_struct *task)
{
}


static inline bool blk_needs_flush_plug(struct task_struct *tsk)
{
	return false;
}

#endif 

#endif