include/linux/blk_types.h - linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Block data types and constants.  Directly include this file only to
  * break include dependency loop.
  */
 #ifndef __LINUX_BLK_TYPES_H
 #define __LINUX_BLK_TYPES_H

 #include <linux/types.h>
 #include <linux/bvec.h>
 #include <linux/ktime.h>

 struct bio_set;
 struct bio;
 struct bio_integrity_payload;
 struct page;
 struct block_device;
 struct io_context;
 struct cgroup_subsys_state;
 typedef void (bio_end_io_t) (struct bio *);

 /*
  * Block error status values.  See block/blk-core:blk_errors for the details.
  * Alpha cannot write a byte atomically, so we need to use 32-bit value.
  */
 #if defined(CONFIG_ALPHA) && !defined(__alpha_bwx__)
 typedef u32 __bitwise blk_status_t;
 #else
 typedef u8 __bitwise blk_status_t;
 #endif
 #define	BLK_STS_OK 0
 #define BLK_STS_NOTSUPP		((__force blk_status_t)1)
 #define BLK_STS_TIMEOUT		((__force blk_status_t)2)
 #define BLK_STS_NOSPC		((__force blk_status_t)3)
 #define BLK_STS_TRANSPORT	((__force blk_status_t)4)
 #define BLK_STS_TARGET		((__force blk_status_t)5)
 #define BLK_STS_NEXUS		((__force blk_status_t)6)
 #define BLK_STS_MEDIUM		((__force blk_status_t)7)
 #define BLK_STS_PROTECTION	((__force blk_status_t)8)
 #define BLK_STS_RESOURCE	((__force blk_status_t)9)
 #define BLK_STS_IOERR		((__force blk_status_t)10)

 /* hack for device mapper, don't use elsewhere: */
 #define BLK_STS_DM_REQUEUE    ((__force blk_status_t)11)

 #define BLK_STS_AGAIN		((__force blk_status_t)12)

 /*
  * BLK_STS_DEV_RESOURCE is returned from the driver to the block layer if
  * device related resources are unavailable, but the driver can guarantee
  * that the queue will be rerun in the future once resources become
  * available again. This is typically the case for device specific
  * resources that are consumed for IO. If the driver fails allocating these
  * resources, we know that inflight (or pending) IO will free these
  * resource upon completion.
  *
  * This is different from BLK_STS_RESOURCE in that it explicitly references
  * a device specific resource. For resources of wider scope, allocation
  * failure can happen without having pending IO. This means that we can't
  * rely on request completions freeing these resources, as IO may not be in
  * flight. Examples of that are kernel memory allocations, DMA mappings, or
  * any other system wide resources.
  */
 #define BLK_STS_DEV_RESOURCE	((__force blk_status_t)13)

 /**
  * blk_path_error - returns true if error may be path related
  * @error: status the request was completed with
  *
  * Description:
  *     This classifies block error status into non-retryable errors and ones
  *     that may be successful if retried on a failover path.
  *
  * Return:
  *     %false - retrying failover path will not help
  *     %true  - may succeed if retried
  */
 static inline bool blk_path_error(blk_status_t error)
 {
 	switch (error) {
 	case BLK_STS_NOTSUPP:
 	case BLK_STS_NOSPC:
 	case BLK_STS_TARGET:
 	case BLK_STS_NEXUS:
 	case BLK_STS_MEDIUM:
 	case BLK_STS_PROTECTION:
 		return false;
 	}

 	/* Anything else could be a path failure, so should be retried */
 	return true;
 }

 /*
  * From most significant bit:
  * 1 bit: reserved for other usage, see below
  * 12 bits: original size of bio
  * 51 bits: issue time of bio
  */
 #define BIO_ISSUE_RES_BITS      1
 #define BIO_ISSUE_SIZE_BITS     12
 #define BIO_ISSUE_RES_SHIFT     (64 - BIO_ISSUE_RES_BITS)
 #define BIO_ISSUE_SIZE_SHIFT    (BIO_ISSUE_RES_SHIFT - BIO_ISSUE_SIZE_BITS)
 #define BIO_ISSUE_TIME_MASK     ((1ULL << BIO_ISSUE_SIZE_SHIFT) - 1)
 #define BIO_ISSUE_SIZE_MASK     \
 	(((1ULL << BIO_ISSUE_SIZE_BITS) - 1) << BIO_ISSUE_SIZE_SHIFT)
 #define BIO_ISSUE_RES_MASK      (~((1ULL << BIO_ISSUE_RES_SHIFT) - 1))

 /* Reserved bit for blk-throtl */
 #define BIO_ISSUE_THROTL_SKIP_LATENCY (1ULL << 63)

 struct bio_issue {
 	u64 value;
 };

 static inline u64 __bio_issue_time(u64 time)
 {
 	return time & BIO_ISSUE_TIME_MASK;
 }

 static inline u64 bio_issue_time(struct bio_issue *issue)
 {
 	return __bio_issue_time(issue->value);
 }

 static inline sector_t bio_issue_size(struct bio_issue *issue)
 {
 	return ((issue->value & BIO_ISSUE_SIZE_MASK) >> BIO_ISSUE_SIZE_SHIFT);
 }

 static inline void bio_issue_init(struct bio_issue *issue,
 				       sector_t size)
 {
 	size &= (1ULL << BIO_ISSUE_SIZE_BITS) - 1;
 	issue->value = ((issue->value & BIO_ISSUE_RES_MASK) |
 			(ktime_get_ns() & BIO_ISSUE_TIME_MASK) |
 			((u64)size << BIO_ISSUE_SIZE_SHIFT));
 }

 /*
  * main unit of I/O for the block layer and lower layers (ie drivers and
  * stacking drivers)
  */
 struct bio {
 	struct bio		*bi_next;	/* request queue link */
 	struct gendisk		*bi_disk;
 	unsigned int		bi_opf;		/* bottom bits req flags,
 						 * top bits REQ_OP. Use
 						 * accessors.
 						 */
 	unsigned short		bi_flags;	/* status, etc and bvec pool number */
 	unsigned short		bi_ioprio;
 	unsigned short		bi_write_hint;
 	blk_status_t		bi_status;
 	u8			bi_partno;

 	/* Number of segments in this BIO after
 	 * physical address coalescing is performed.
 	 */
 	unsigned int		bi_phys_segments;

 	/*
 	 * To keep track of the max segment size, we account for the
 	 * sizes of the first and last mergeable segments in this bio.
 	 */
 	unsigned int		bi_seg_front_size;
 	unsigned int		bi_seg_back_size;

 	struct bvec_iter	bi_iter;

 	atomic_t		__bi_remaining;
 	bio_end_io_t		*bi_end_io;

 	void			*bi_private;
 #ifdef CONFIG_BLK_CGROUP
 	/*
 	 * Optional ioc and css associated with this bio.  Put on bio
 	 * release.  Read comment on top of bio_associate_current().
 	 */
 	struct io_context	*bi_ioc;
 	struct cgroup_subsys_state *bi_css;
 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
 	void			*bi_cg_private;
 	struct bio_issue	bi_issue;
 #endif
 #endif
 	union {
 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 		struct bio_integrity_payload *bi_integrity; /* data integrity */
 #endif
 	};

 	unsigned short		bi_vcnt;	/* how many bio_vec's */

 	/*
 	 * Everything starting with bi_max_vecs will be preserved by bio_reset()
 	 */

 	unsigned short		bi_max_vecs;	/* max bvl_vecs we can hold */

 	atomic_t		__bi_cnt;	/* pin count */

 	struct bio_vec		*bi_io_vec;	/* the actual vec list */

 	struct bio_set		*bi_pool;

 	/*
 	 * We can inline a number of vecs at the end of the bio, to avoid
 	 * double allocations for a small number of bio_vecs. This member
 	 * MUST obviously be kept at the very end of the bio.
 	 */
 	struct bio_vec		bi_inline_vecs[0];
 };

 #define BIO_RESET_BYTES		offsetof(struct bio, bi_max_vecs)

 /*
  * bio flags
  */
 #define BIO_SEG_VALID	1	/* bi_phys_segments valid */
 #define BIO_CLONED	2	/* doesn't own data */
 #define BIO_BOUNCED	3	/* bio is a bounce bio */
 #define BIO_USER_MAPPED 4	/* contains user pages */
 #define BIO_NULL_MAPPED 5	/* contains invalid user pages */
 #define BIO_QUIET	6	/* Make BIO Quiet */
 #define BIO_CHAIN	7	/* chained bio, ->bi_remaining in effect */
 #define BIO_REFFED	8	/* bio has elevated ->bi_cnt */
 #define BIO_THROTTLED	9	/* This bio has already been subjected to
 				 * throttling rules. Don't do it again. */
 #define BIO_TRACE_COMPLETION 10	/* bio_endio() should trace the final completion
 				 * of this bio. */
 #define BIO_QUEUE_ENTERED 11	/* can use blk_queue_enter_live() */

 /* See BVEC_POOL_OFFSET below before adding new flags */

 /*
  * We support 6 different bvec pools, the last one is magic in that it
  * is backed by a mempool.
  */
 #define BVEC_POOL_NR		6
 #define BVEC_POOL_MAX		(BVEC_POOL_NR - 1)

 /*
  * Top 3 bits of bio flags indicate the pool the bvecs came from.  We add
  * 1 to the actual index so that 0 indicates that there are no bvecs to be
  * freed.
  */
 #define BVEC_POOL_BITS		(3)
 #define BVEC_POOL_OFFSET	(16 - BVEC_POOL_BITS)
 #define BVEC_POOL_IDX(bio)	((bio)->bi_flags >> BVEC_POOL_OFFSET)
 #if (1<< BVEC_POOL_BITS) < (BVEC_POOL_NR+1)
 # error "BVEC_POOL_BITS is too small"
 #endif

 /*
  * Flags starting here get preserved by bio_reset() - this includes
  * only BVEC_POOL_IDX()
  */
 #define BIO_RESET_BITS	BVEC_POOL_OFFSET

 typedef __u32 __bitwise blk_mq_req_flags_t;

 /*
  * Operations and flags common to the bio and request structures.
  * We use 8 bits for encoding the operation, and the remaining 24 for flags.
  *
  * The least significant bit of the operation number indicates the data
  * transfer direction:
  *
  *   - if the least significant bit is set transfers are TO the device
  *   - if the least significant bit is not set transfers are FROM the device
  *
  * If a operation does not transfer data the least significant bit has no
  * meaning.
  */
 #define REQ_OP_BITS	8
 #define REQ_OP_MASK	((1 << REQ_OP_BITS) - 1)
 #define REQ_FLAG_BITS	24

 enum req_opf {
 	/* read sectors from the device */
 	REQ_OP_READ		= 0,
 	/* write sectors to the device */
 	REQ_OP_WRITE		= 1,
 	/* flush the volatile write cache */
 	REQ_OP_FLUSH		= 2,
 	/* discard sectors */
 	REQ_OP_DISCARD		= 3,
 	/* get zone information */
 	REQ_OP_ZONE_REPORT	= 4,
 	/* securely erase sectors */
 	REQ_OP_SECURE_ERASE	= 5,
 	/* seset a zone write pointer */
 	REQ_OP_ZONE_RESET	= 6,
 	/* write the same sector many times */
 	REQ_OP_WRITE_SAME	= 7,
 	/* write the zero filled sector many times */
 	REQ_OP_WRITE_ZEROES	= 9,

 	/* SCSI passthrough using struct scsi_request */
 	REQ_OP_SCSI_IN		= 32,
 	REQ_OP_SCSI_OUT		= 33,
 	/* Driver private requests */
 	REQ_OP_DRV_IN		= 34,
 	REQ_OP_DRV_OUT		= 35,

 	REQ_OP_LAST,
 };

 enum req_flag_bits {
 	__REQ_FAILFAST_DEV =	/* no driver retries of device errors */
 		REQ_OP_BITS,
 	__REQ_FAILFAST_TRANSPORT, /* no driver retries of transport errors */
 	__REQ_FAILFAST_DRIVER,	/* no driver retries of driver errors */
 	__REQ_SYNC,		/* request is sync (sync write or read) */
 	__REQ_META,		/* metadata io request */
 	__REQ_PRIO,		/* boost priority in cfq */
 	__REQ_NOMERGE,		/* don't touch this for merging */
 	__REQ_IDLE,		/* anticipate more IO after this one */
 	__REQ_INTEGRITY,	/* I/O includes block integrity payload */
 	__REQ_FUA,		/* forced unit access */
 	__REQ_PREFLUSH,		/* request for cache flush */
 	__REQ_RAHEAD,		/* read ahead, can fail anytime */
 	__REQ_BACKGROUND,	/* background IO */
 	__REQ_NOWAIT,           /* Don't wait if request will block */

 	/* command specific flags for REQ_OP_WRITE_ZEROES: */
 	__REQ_NOUNMAP,		/* do not free blocks when zeroing */

 	/* for driver use */
 	__REQ_DRV,

 	__REQ_NR_BITS,		/* stops here */
 };

 #define REQ_FAILFAST_DEV	(1ULL << __REQ_FAILFAST_DEV)
 #define REQ_FAILFAST_TRANSPORT	(1ULL << __REQ_FAILFAST_TRANSPORT)
 #define REQ_FAILFAST_DRIVER	(1ULL << __REQ_FAILFAST_DRIVER)
 #define REQ_SYNC		(1ULL << __REQ_SYNC)
 #define REQ_META		(1ULL << __REQ_META)
 #define REQ_PRIO		(1ULL << __REQ_PRIO)
 #define REQ_NOMERGE		(1ULL << __REQ_NOMERGE)
 #define REQ_IDLE		(1ULL << __REQ_IDLE)
 #define REQ_INTEGRITY		(1ULL << __REQ_INTEGRITY)
 #define REQ_FUA			(1ULL << __REQ_FUA)
 #define REQ_PREFLUSH		(1ULL << __REQ_PREFLUSH)
 #define REQ_RAHEAD		(1ULL << __REQ_RAHEAD)
 #define REQ_BACKGROUND		(1ULL << __REQ_BACKGROUND)
 #define REQ_NOWAIT		(1ULL << __REQ_NOWAIT)

 #define REQ_NOUNMAP		(1ULL << __REQ_NOUNMAP)

 #define REQ_DRV			(1ULL << __REQ_DRV)

 #define REQ_FAILFAST_MASK \
 	(REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER)

 #define REQ_NOMERGE_FLAGS \
 	(REQ_NOMERGE | REQ_PREFLUSH | REQ_FUA)

 #define bio_op(bio) \
 	((bio)->bi_opf & REQ_OP_MASK)
 #define req_op(req) \
 	((req)->cmd_flags & REQ_OP_MASK)

 /* obsolete, don't use in new code */
 static inline void bio_set_op_attrs(struct bio *bio, unsigned op,
 		unsigned op_flags)
 {
 	bio->bi_opf = op | op_flags;
 }

 static inline bool op_is_write(unsigned int op)
 {
 	return (op & 1);
 }

 /*
  * Check if the bio or request is one that needs special treatment in the
  * flush state machine.
  */
 static inline bool op_is_flush(unsigned int op)
 {
 	return op & (REQ_FUA | REQ_PREFLUSH);
 }

 /*
  * Reads are always treated as synchronous, as are requests with the FUA or
  * PREFLUSH flag.  Other operations may be marked as synchronous using the
  * REQ_SYNC flag.
  */
 static inline bool op_is_sync(unsigned int op)
 {
 	return (op & REQ_OP_MASK) == REQ_OP_READ ||
 		(op & (REQ_SYNC | REQ_FUA | REQ_PREFLUSH));
 }

 typedef unsigned int blk_qc_t;
 #define BLK_QC_T_NONE		-1U
 #define BLK_QC_T_SHIFT		16
 #define BLK_QC_T_INTERNAL	(1U << 31)

 static inline bool blk_qc_t_valid(blk_qc_t cookie)
 {
 	return cookie != BLK_QC_T_NONE;
 }

 static inline blk_qc_t blk_tag_to_qc_t(unsigned int tag, unsigned int queue_num,
 				       bool internal)
 {
 	blk_qc_t ret = tag | (queue_num << BLK_QC_T_SHIFT);

 	if (internal)
 		ret |= BLK_QC_T_INTERNAL;

 	return ret;
 }

 static inline unsigned int blk_qc_t_to_queue_num(blk_qc_t cookie)
 {
 	return (cookie & ~BLK_QC_T_INTERNAL) >> BLK_QC_T_SHIFT;
 }

 static inline unsigned int blk_qc_t_to_tag(blk_qc_t cookie)
 {
 	return cookie & ((1u << BLK_QC_T_SHIFT) - 1);
 }

 static inline bool blk_qc_t_is_internal(blk_qc_t cookie)
 {
 	return (cookie & BLK_QC_T_INTERNAL) != 0;
 }

 struct blk_rq_stat {
 	u64 mean;
 	u64 min;
 	u64 max;
 	u32 nr_samples;
 	u64 batch;
 };

 #endif /* __LINUX_BLK_TYPES_H */
	/* SPDX-License-Identifier: GPL-2.0 */
	/*
	* Block data types and constants. Directly include this file only to
	* break include dependency loop.
	*/
	#ifndef __LINUX_BLK_TYPES_H
	#define __LINUX_BLK_TYPES_H

	#include <linux/types.h>
	#include <linux/bvec.h>
	#include <linux/ktime.h>

	struct bio_set;
	struct bio;
	struct bio_integrity_payload;
	struct page;
	struct block_device;
	struct io_context;
	struct cgroup_subsys_state;
	typedef void (bio_end_io_t) (struct bio *);

	/*
	* Block error status values. See block/blk-core:blk_errors for the details.
	* Alpha cannot write a byte atomically, so we need to use 32-bit value.
	*/
	#if defined(CONFIG_ALPHA) && !defined(__alpha_bwx__)
	typedef u32 __bitwise blk_status_t;
	#else
	typedef u8 __bitwise blk_status_t;
	#endif
	#define BLK_STS_OK 0
	#define BLK_STS_NOTSUPP ((__force blk_status_t)1)
	#define BLK_STS_TIMEOUT ((__force blk_status_t)2)
	#define BLK_STS_NOSPC ((__force blk_status_t)3)
	#define BLK_STS_TRANSPORT ((__force blk_status_t)4)
	#define BLK_STS_TARGET ((__force blk_status_t)5)
	#define BLK_STS_NEXUS ((__force blk_status_t)6)
	#define BLK_STS_MEDIUM ((__force blk_status_t)7)
	#define BLK_STS_PROTECTION ((__force blk_status_t)8)
	#define BLK_STS_RESOURCE ((__force blk_status_t)9)
	#define BLK_STS_IOERR ((__force blk_status_t)10)

	/* hack for device mapper, don't use elsewhere: */
	#define BLK_STS_DM_REQUEUE ((__force blk_status_t)11)

	#define BLK_STS_AGAIN ((__force blk_status_t)12)

	/*
	* BLK_STS_DEV_RESOURCE is returned from the driver to the block layer if
	* device related resources are unavailable, but the driver can guarantee
	* that the queue will be rerun in the future once resources become
	* available again. This is typically the case for device specific
	* resources that are consumed for IO. If the driver fails allocating these
	* resources, we know that inflight (or pending) IO will free these
	* resource upon completion.
	*
	* This is different from BLK_STS_RESOURCE in that it explicitly references
	* a device specific resource. For resources of wider scope, allocation
	* failure can happen without having pending IO. This means that we can't
	* rely on request completions freeing these resources, as IO may not be in
	* flight. Examples of that are kernel memory allocations, DMA mappings, or
	* any other system wide resources.
	*/
	#define BLK_STS_DEV_RESOURCE ((__force blk_status_t)13)

	/**
	* blk_path_error - returns true if error may be path related
	* @error: status the request was completed with
	*
	* Description:
	* This classifies block error status into non-retryable errors and ones
	* that may be successful if retried on a failover path.
	*
	* Return:
	* %false - retrying failover path will not help
	* %true - may succeed if retried
	*/
	static inline bool blk_path_error(blk_status_t error)
	{
	switch (error) {
	case BLK_STS_NOTSUPP:
	case BLK_STS_NOSPC:
	case BLK_STS_TARGET:
	case BLK_STS_NEXUS:
	case BLK_STS_MEDIUM:
	case BLK_STS_PROTECTION:
	return false;
	}

	/* Anything else could be a path failure, so should be retried */
	return true;
	}

	/*
	* From most significant bit:
	* 1 bit: reserved for other usage, see below
	* 12 bits: original size of bio
	* 51 bits: issue time of bio
	*/
	#define BIO_ISSUE_RES_BITS 1
	#define BIO_ISSUE_SIZE_BITS 12
	#define BIO_ISSUE_RES_SHIFT (64 - BIO_ISSUE_RES_BITS)
	#define BIO_ISSUE_SIZE_SHIFT (BIO_ISSUE_RES_SHIFT - BIO_ISSUE_SIZE_BITS)
	#define BIO_ISSUE_TIME_MASK ((1ULL << BIO_ISSUE_SIZE_SHIFT) - 1)
	#define BIO_ISSUE_SIZE_MASK \
	(((1ULL << BIO_ISSUE_SIZE_BITS) - 1) << BIO_ISSUE_SIZE_SHIFT)
	#define BIO_ISSUE_RES_MASK (~((1ULL << BIO_ISSUE_RES_SHIFT) - 1))

	/* Reserved bit for blk-throtl */
	#define BIO_ISSUE_THROTL_SKIP_LATENCY (1ULL << 63)

	struct bio_issue {
	u64 value;
	};

	static inline u64 __bio_issue_time(u64 time)
	{
	return time & BIO_ISSUE_TIME_MASK;
	}

	static inline u64 bio_issue_time(struct bio_issue *issue)
	{
	return __bio_issue_time(issue->value);
	}

	static inline sector_t bio_issue_size(struct bio_issue *issue)
	{
	return ((issue->value & BIO_ISSUE_SIZE_MASK) >> BIO_ISSUE_SIZE_SHIFT);
	}

	static inline void bio_issue_init(struct bio_issue *issue,
	sector_t size)
	{
	size &= (1ULL << BIO_ISSUE_SIZE_BITS) - 1;
	issue->value = ((issue->value & BIO_ISSUE_RES_MASK) \|
	(ktime_get_ns() & BIO_ISSUE_TIME_MASK) \|
	((u64)size << BIO_ISSUE_SIZE_SHIFT));
	}

	/*
	* main unit of I/O for the block layer and lower layers (ie drivers and
	* stacking drivers)
	*/
	struct bio {
	struct bio bi_next; / request queue link */
	struct gendisk *bi_disk;
	unsigned int bi_opf; /* bottom bits req flags,
	* top bits REQ_OP. Use
	* accessors.
	*/
	unsigned short bi_flags; /* status, etc and bvec pool number */
	unsigned short bi_ioprio;
	unsigned short bi_write_hint;
	blk_status_t bi_status;
	u8 bi_partno;

	/* Number of segments in this BIO after
	* physical address coalescing is performed.
	*/
	unsigned int bi_phys_segments;

	/*
	* To keep track of the max segment size, we account for the
	* sizes of the first and last mergeable segments in this bio.
	*/
	unsigned int bi_seg_front_size;
	unsigned int bi_seg_back_size;

	struct bvec_iter bi_iter;

	atomic_t __bi_remaining;
	bio_end_io_t *bi_end_io;

	void *bi_private;
	#ifdef CONFIG_BLK_CGROUP
	/*
	* Optional ioc and css associated with this bio. Put on bio
	* release. Read comment on top of bio_associate_current().
	*/
	struct io_context *bi_ioc;
	struct cgroup_subsys_state *bi_css;
	#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
	void *bi_cg_private;
	struct bio_issue bi_issue;
	#endif
	#endif
	union {
	#if defined(CONFIG_BLK_DEV_INTEGRITY)
	struct bio_integrity_payload bi_integrity; / data integrity */
	#endif
	};

	unsigned short bi_vcnt; /* how many bio_vec's */

	/*
	* Everything starting with bi_max_vecs will be preserved by bio_reset()
	*/

	unsigned short bi_max_vecs; /* max bvl_vecs we can hold */

	atomic_t __bi_cnt; /* pin count */

	struct bio_vec bi_io_vec; / the actual vec list */

	struct bio_set *bi_pool;

	/*
	* We can inline a number of vecs at the end of the bio, to avoid
	* double allocations for a small number of bio_vecs. This member
	* MUST obviously be kept at the very end of the bio.
	*/
	struct bio_vec bi_inline_vecs[0];
	};

	#define BIO_RESET_BYTES offsetof(struct bio, bi_max_vecs)

	/*
	* bio flags
	*/
	#define BIO_SEG_VALID 1 /* bi_phys_segments valid */
	#define BIO_CLONED 2 /* doesn't own data */
	#define BIO_BOUNCED 3 /* bio is a bounce bio */
	#define BIO_USER_MAPPED 4 /* contains user pages */
	#define BIO_NULL_MAPPED 5 /* contains invalid user pages */
	#define BIO_QUIET 6 /* Make BIO Quiet */
	#define BIO_CHAIN 7 /* chained bio, ->bi_remaining in effect */
	#define BIO_REFFED 8 /* bio has elevated ->bi_cnt */
	#define BIO_THROTTLED 9 /* This bio has already been subjected to
	* throttling rules. Don't do it again. */
	#define BIO_TRACE_COMPLETION 10 /* bio_endio() should trace the final completion
	* of this bio. */
	#define BIO_QUEUE_ENTERED 11 /* can use blk_queue_enter_live() */

	/* See BVEC_POOL_OFFSET below before adding new flags */

	/*
	* We support 6 different bvec pools, the last one is magic in that it
	* is backed by a mempool.
	*/
	#define BVEC_POOL_NR 6
	#define BVEC_POOL_MAX (BVEC_POOL_NR - 1)

	/*
	* Top 3 bits of bio flags indicate the pool the bvecs came from. We add
	* 1 to the actual index so that 0 indicates that there are no bvecs to be
	* freed.
	*/
	#define BVEC_POOL_BITS (3)
	#define BVEC_POOL_OFFSET (16 - BVEC_POOL_BITS)
	#define BVEC_POOL_IDX(bio) ((bio)->bi_flags >> BVEC_POOL_OFFSET)
	#if (1<< BVEC_POOL_BITS) < (BVEC_POOL_NR+1)
	# error "BVEC_POOL_BITS is too small"
	#endif

	/*
	* Flags starting here get preserved by bio_reset() - this includes
	* only BVEC_POOL_IDX()
	*/
	#define BIO_RESET_BITS BVEC_POOL_OFFSET

	typedef __u32 __bitwise blk_mq_req_flags_t;

	/*
	* Operations and flags common to the bio and request structures.
	* We use 8 bits for encoding the operation, and the remaining 24 for flags.
	*
	* The least significant bit of the operation number indicates the data
	* transfer direction:
	*
	* - if the least significant bit is set transfers are TO the device
	* - if the least significant bit is not set transfers are FROM the device
	*
	* If a operation does not transfer data the least significant bit has no
	* meaning.
	*/
	#define REQ_OP_BITS 8
	#define REQ_OP_MASK ((1 << REQ_OP_BITS) - 1)
	#define REQ_FLAG_BITS 24

	enum req_opf {
	/* read sectors from the device */
	REQ_OP_READ = 0,
	/* write sectors to the device */
	REQ_OP_WRITE = 1,
	/* flush the volatile write cache */
	REQ_OP_FLUSH = 2,
	/* discard sectors */
	REQ_OP_DISCARD = 3,
	/* get zone information */
	REQ_OP_ZONE_REPORT = 4,
	/* securely erase sectors */
	REQ_OP_SECURE_ERASE = 5,
	/* seset a zone write pointer */
	REQ_OP_ZONE_RESET = 6,
	/* write the same sector many times */
	REQ_OP_WRITE_SAME = 7,
	/* write the zero filled sector many times */
	REQ_OP_WRITE_ZEROES = 9,

	/* SCSI passthrough using struct scsi_request */
	REQ_OP_SCSI_IN = 32,
	REQ_OP_SCSI_OUT = 33,
	/* Driver private requests */
	REQ_OP_DRV_IN = 34,
	REQ_OP_DRV_OUT = 35,

	REQ_OP_LAST,
	};

	enum req_flag_bits {
	__REQ_FAILFAST_DEV = /* no driver retries of device errors */
	REQ_OP_BITS,
	__REQ_FAILFAST_TRANSPORT, /* no driver retries of transport errors */
	__REQ_FAILFAST_DRIVER, /* no driver retries of driver errors */
	__REQ_SYNC, /* request is sync (sync write or read) */
	__REQ_META, /* metadata io request */
	__REQ_PRIO, /* boost priority in cfq */
	__REQ_NOMERGE, /* don't touch this for merging */
	__REQ_IDLE, /* anticipate more IO after this one */
	__REQ_INTEGRITY, /* I/O includes block integrity payload */
	__REQ_FUA, /* forced unit access */
	__REQ_PREFLUSH, /* request for cache flush */
	__REQ_RAHEAD, /* read ahead, can fail anytime */
	__REQ_BACKGROUND, /* background IO */
	__REQ_NOWAIT, /* Don't wait if request will block */

	/* command specific flags for REQ_OP_WRITE_ZEROES: */
	__REQ_NOUNMAP, /* do not free blocks when zeroing */

	/* for driver use */
	__REQ_DRV,

	__REQ_NR_BITS, /* stops here */
	};

	#define REQ_FAILFAST_DEV (1ULL << __REQ_FAILFAST_DEV)
	#define REQ_FAILFAST_TRANSPORT (1ULL << __REQ_FAILFAST_TRANSPORT)
	#define REQ_FAILFAST_DRIVER (1ULL << __REQ_FAILFAST_DRIVER)
	#define REQ_SYNC (1ULL << __REQ_SYNC)
	#define REQ_META (1ULL << __REQ_META)
	#define REQ_PRIO (1ULL << __REQ_PRIO)
	#define REQ_NOMERGE (1ULL << __REQ_NOMERGE)
	#define REQ_IDLE (1ULL << __REQ_IDLE)
	#define REQ_INTEGRITY (1ULL << __REQ_INTEGRITY)
	#define REQ_FUA (1ULL << __REQ_FUA)
	#define REQ_PREFLUSH (1ULL << __REQ_PREFLUSH)
	#define REQ_RAHEAD (1ULL << __REQ_RAHEAD)
	#define REQ_BACKGROUND (1ULL << __REQ_BACKGROUND)
	#define REQ_NOWAIT (1ULL << __REQ_NOWAIT)

	#define REQ_NOUNMAP (1ULL << __REQ_NOUNMAP)

	#define REQ_DRV (1ULL << __REQ_DRV)

	#define REQ_FAILFAST_MASK \
	(REQ_FAILFAST_DEV \| REQ_FAILFAST_TRANSPORT \| REQ_FAILFAST_DRIVER)

	#define REQ_NOMERGE_FLAGS \
	(REQ_NOMERGE \| REQ_PREFLUSH \| REQ_FUA)

	#define bio_op(bio) \
	((bio)->bi_opf & REQ_OP_MASK)
	#define req_op(req) \
	((req)->cmd_flags & REQ_OP_MASK)

	/* obsolete, don't use in new code */
	static inline void bio_set_op_attrs(struct bio *bio, unsigned op,
	unsigned op_flags)
	{
	bio->bi_opf = op \| op_flags;
	}

	static inline bool op_is_write(unsigned int op)
	{
	return (op & 1);
	}

	/*
	* Check if the bio or request is one that needs special treatment in the
	* flush state machine.
	*/
	static inline bool op_is_flush(unsigned int op)
	{
	return op & (REQ_FUA \| REQ_PREFLUSH);
	}

	/*
	* Reads are always treated as synchronous, as are requests with the FUA or
	* PREFLUSH flag. Other operations may be marked as synchronous using the
	* REQ_SYNC flag.
	*/
	static inline bool op_is_sync(unsigned int op)
	{
	return (op & REQ_OP_MASK) == REQ_OP_READ \|\|
	(op & (REQ_SYNC \| REQ_FUA \| REQ_PREFLUSH));
	}

	typedef unsigned int blk_qc_t;
	#define BLK_QC_T_NONE -1U
	#define BLK_QC_T_SHIFT 16
	#define BLK_QC_T_INTERNAL (1U << 31)

	static inline bool blk_qc_t_valid(blk_qc_t cookie)
	{
	return cookie != BLK_QC_T_NONE;
	}

	static inline blk_qc_t blk_tag_to_qc_t(unsigned int tag, unsigned int queue_num,
	bool internal)
	{
	blk_qc_t ret = tag \| (queue_num << BLK_QC_T_SHIFT);

	if (internal)
	ret \|= BLK_QC_T_INTERNAL;

	return ret;
	}

	static inline unsigned int blk_qc_t_to_queue_num(blk_qc_t cookie)
	{
	return (cookie & ~BLK_QC_T_INTERNAL) >> BLK_QC_T_SHIFT;
	}

	static inline unsigned int blk_qc_t_to_tag(blk_qc_t cookie)
	{
	return cookie & ((1u << BLK_QC_T_SHIFT) - 1);
	}

	static inline bool blk_qc_t_is_internal(blk_qc_t cookie)
	{
	return (cookie & BLK_QC_T_INTERNAL) != 0;
	}

	struct blk_rq_stat {
	u64 mean;
	u64 min;
	u64 max;
	u32 nr_samples;
	u64 batch;
	};

	#endif /* __LINUX_BLK_TYPES_H */