text: /*
   * 2.5 block I/O model
   *
   * Copyright (C) 2001 Jens Axboe <axboe@suse.de>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   *
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public Licens
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
   */
  #ifndef __LINUX_BIO_H
  #define __LINUX_BIO_H
  
  #include <linux/highmem.h>
  #include <linux/mempool.h>
  #include <linux/ioprio.h>
  #include <linux/bug.h>
  
  #ifdef CONFIG_BLOCK
  
  #include <asm/io.h>
  
  /* struct bio, bio_vec and BIO_* flags are defined in blk_types.h */
  #include <linux/blk_types.h>
  
  #define BIO_DEBUG
  
  #ifdef BIO_DEBUG
  #define BIO_BUG_ON	BUG_ON
  #else
  #define BIO_BUG_ON
  #endif
  
  #define BIO_MAX_PAGES		256
  #define BIO_MAX_SIZE		(BIO_MAX_PAGES << PAGE_CACHE_SHIFT)
  #define BIO_MAX_SECTORS		(BIO_MAX_SIZE >> 9)
  
  /*
   * upper 16 bits of bi_rw define the io priority of this bio
   */
  #define BIO_PRIO_SHIFT	(8 * sizeof(unsigned long) - IOPRIO_BITS)
  #define bio_prio(bio)	((bio)->bi_rw >> BIO_PRIO_SHIFT)
  #define bio_prio_valid(bio)	ioprio_valid(bio_prio(bio))
  
  #define bio_set_prio(bio, prio)		do {			\
  	WARN_ON(prio >= (1 << IOPRIO_BITS));			\
  	(bio)->bi_rw &= ((1UL << BIO_PRIO_SHIFT) - 1);		\
  	(bio)->bi_rw |= ((unsigned long) (prio) << BIO_PRIO_SHIFT);	\
  } while (0)
  
  /*
   * various member access, note that bio_data should of course not be used
   * on highmem page vectors
   */
  #define bio_iovec_idx(bio, idx)	(&((bio)->bi_io_vec[(idx)]))
  #define bio_iovec(bio)		bio_iovec_idx((bio), (bio)->bi_idx)
  #define bio_page(bio)		bio_iovec((bio))->bv_page
  #define bio_offset(bio)		bio_iovec((bio))->bv_offset
  #define bio_segments(bio)	((bio)->bi_vcnt - (bio)->bi_idx)
  #define bio_sectors(bio)	((bio)->bi_size >> 9)
  #define bio_end_sector(bio)	((bio)->bi_sector + bio_sectors((bio)))
  
  static inline unsigned int bio_cur_bytes(struct bio *bio)
  {
  	if (bio->bi_vcnt)
  		return bio_iovec(bio)->bv_len;
  	else /* dataless requests such as discard */
  		return bio->bi_size;
  }
  
  static inline void *bio_data(struct bio *bio)
  {
  	if (bio->bi_vcnt)
  		return page_address(bio_page(bio)) + bio_offset(bio);
  
  	return NULL;
  }
  
  /*
   * will die
   */
  #define bio_to_phys(bio)	(page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio)))
  #define bvec_to_phys(bv)	(page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
  
  /*
   * queues that have highmem support enabled may still need to revert to
   * PIO transfers occasionally and thus map high pages temporarily. For
   * permanent PIO fall back, user is probably better off disabling highmem
   * I/O completely on that queue (see ide-dma for example)
   */
  #define __bio_kmap_atomic(bio, idx)				\
  	(kmap_atomic(bio_iovec_idx((bio), (idx))->bv_page) +	\
  		bio_iovec_idx((bio), (idx))->bv_offset)
  
  #define __bio_kunmap_atomic(addr) kunmap_atomic(addr)
  
  /*
   * merge helpers etc
   */
  
  #define __BVEC_END(bio)		bio_iovec_idx((bio), (bio)->bi_vcnt - 1)
  #define __BVEC_START(bio)	bio_iovec_idx((bio), (bio)->bi_idx)
  
  /* Default implementation of BIOVEC_PHYS_MERGEABLE */
  #define __BIOVEC_PHYS_MERGEABLE(vec1, vec2)	\
  	((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
  
  /*
   * allow arch override, for eg virtualized architectures (put in asm/io.h)
   */
  #ifndef BIOVEC_PHYS_MERGEABLE
  #define BIOVEC_PHYS_MERGEABLE(vec1, vec2)	\
  	__BIOVEC_PHYS_MERGEABLE(vec1, vec2)
  #endif
  
  #define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
  	(((addr1) | (mask)) == (((addr2) - 1) | (mask)))
  #define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
  	__BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, queue_segment_boundary((q)))
  #define BIO_SEG_BOUNDARY(q, b1, b2) \
  	BIOVEC_SEG_BOUNDARY((q), __BVEC_END((b1)), __BVEC_START((b2)))
  
  #define bio_io_error(bio) bio_endio((bio), -EIO)
  
  /*
   * drivers should not use the __ version unless they _really_ know what
   * they're doing
   */
  #define __bio_for_each_segment(bvl, bio, i, start_idx)			\
  	for (bvl = bio_iovec_idx((bio), (start_idx)), i = (start_idx);	\
  	     i < (bio)->bi_vcnt;					\
  	     bvl++, i++)
  
  /*
   * drivers should _never_ use the all version - the bio may have been split
   * before it got to the driver and the driver won't own all of it
   */
  #define bio_for_each_segment_all(bvl, bio, i)				\
  	for (i = 0;							\
  	     bvl = bio_iovec_idx((bio), (i)), i < (bio)->bi_vcnt;	\
  	     i++)
  
  #define bio_for_each_segment(bvl, bio, i)				\
  	for (i = (bio)->bi_idx;						\
  	     bvl = bio_iovec_idx((bio), (i)), i < (bio)->bi_vcnt;	\
  	     i++)
  
  /*
   * get a reference to a bio, so it won't disappear. the intended use is
   * something like:
   *
   * bio_get(bio);
   * submit_bio(rw, bio);
   * if (bio->bi_flags ...)
   *	do_something
   * bio_put(bio);
   *
   * without the bio_get(), it could potentially complete I/O before submit_bio
   * returns. and then bio would be freed memory when if (bio->bi_flags ...)
   * runs
   */
  #define bio_get(bio)	atomic_inc(&(bio)->bi_cnt)
  
  #if defined(CONFIG_BLK_DEV_INTEGRITY)
  /*
   * bio integrity payload
   */
  struct bio_integrity_payload {
  	struct bio		*bip_bio;	/* parent bio */
  
  	sector_t		bip_sector;	/* virtual start sector */
  
  	void			*bip_buf;	/* generated integrity data */
  	bio_end_io_t		*bip_end_io;	/* saved I/O completion fn */
  
  	unsigned int		bip_size;
  
  	unsigned short		bip_slab;	/* slab the bip came from */
  	unsigned short		bip_vcnt;	/* # of integrity bio_vecs */
  	unsigned short		bip_idx;	/* current bip_vec index */
  	unsigned		bip_owns_buf:1;	/* should free bip_buf */
  
  	struct work_struct	bip_work;	/* I/O completion */
  
  	struct bio_vec		*bip_vec;
  	struct bio_vec		bip_inline_vecs[0];/* embedded bvec array */
  };
  #endif /* CONFIG_BLK_DEV_INTEGRITY */
  
  /*
   * A bio_pair is used when we need to split a bio.
   * This can only happen for a bio that refers to just one
   * page of data, and in the unusual situation when the
   * page crosses a chunk/device boundary
   *
   * The address of the master bio is stored in bio1.bi_private
   * The address of the pool the pair was allocated from is stored
   *   in bio2.bi_private
   */
  struct bio_pair {
  	struct bio			bio1, bio2;
  	struct bio_vec			bv1, bv2;
  #if defined(CONFIG_BLK_DEV_INTEGRITY)
  	struct bio_integrity_payload	bip1, bip2;
  	struct bio_vec			iv1, iv2;
  #endif
  	atomic_t			cnt;
  	int				error;
  };
  extern struct bio_pair *bio_split(struct bio *bi, int first_sectors);
  extern void bio_pair_release(struct bio_pair *dbio);
  extern void bio_trim(struct bio *bio, int offset, int size);
  
  extern struct bio_set *bioset_create(unsigned int, unsigned int);
  extern void bioset_free(struct bio_set *);
  extern mempool_t *biovec_create_pool(struct bio_set *bs, int pool_entries);
  
  extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
  extern void bio_put(struct bio *);
  
  extern void __bio_clone(struct bio *, struct bio *);
  extern struct bio *bio_clone_bioset(struct bio *, gfp_t, struct bio_set *bs);
  
  extern struct bio_set *fs_bio_set;
  
  static inline struct bio *bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
  {
  	return bio_alloc_bioset(gfp_mask, nr_iovecs, fs_bio_set);
  }
  
  static inline struct bio *bio_clone(struct bio *bio, gfp_t gfp_mask)
  {
  	return bio_clone_bioset(bio, gfp_mask, fs_bio_set);
  }
  
  static inline struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned int nr_iovecs)
  {
  	return bio_alloc_bioset(gfp_mask, nr_iovecs, NULL);
  }
  
  static inline struct bio *bio_clone_kmalloc(struct bio *bio, gfp_t gfp_mask)
  {
  	return bio_clone_bioset(bio, gfp_mask, NULL);
  
  }
  
  extern void bio_endio(struct bio *, int);
  struct request_queue;
  extern int bio_phys_segments(struct request_queue *, struct bio *);
  
  extern int submit_bio_wait(int rw, struct bio *bio);
  extern void bio_advance(struct bio *, unsigned);
  
  extern void bio_init(struct bio *);
  extern void bio_reset(struct bio *);
  
  extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
  extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
  			   unsigned int, unsigned int);
  extern int bio_get_nr_vecs(struct block_device *);
  extern sector_t bio_sector_offset(struct bio *, unsigned short, unsigned int);
  extern struct bio *bio_map_user(struct request_queue *, struct block_device *,
  				unsigned long, unsigned int, int, gfp_t);
  struct sg_iovec;
  struct rq_map_data;
  extern struct bio *bio_map_user_iov(struct request_queue *,
  				    struct block_device *,
  				    struct sg_iovec *, int, int, gfp_t);
  extern void bio_unmap_user(struct bio *);
  extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
  				gfp_t);
  extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
  				 gfp_t, int);
  extern void bio_set_pages_dirty(struct bio *bio);
  extern void bio_check_pages_dirty(struct bio *bio);
  
  #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 bio_flush_dcache_pages(struct bio *bi);
  #else
  static inline void bio_flush_dcache_pages(struct bio *bi)
  {
  }
  #endif
  
  extern void bio_copy_data(struct bio *dst, struct bio *src);
  extern int bio_alloc_pages(struct bio *bio, gfp_t gfp);
  
  extern struct bio *bio_copy_user(struct request_queue *, struct rq_map_data *,
  				 unsigned long, unsigned int, int, gfp_t);
  extern struct bio *bio_copy_user_iov(struct request_queue *,
  				     struct rq_map_data *, struct sg_iovec *,
  				     int, int, gfp_t);
  extern int bio_uncopy_user(struct bio *);
  void zero_fill_bio(struct bio *bio);
  extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *);
  extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
  extern unsigned int bvec_nr_vecs(unsigned short idx);
  
  #ifdef CONFIG_BLK_CGROUP
  int bio_associate_current(struct bio *bio);
  void bio_disassociate_task(struct bio *bio);
  #else	/* CONFIG_BLK_CGROUP */
  static inline int bio_associate_current(struct bio *bio) { return -ENOENT; }
  static inline void bio_disassociate_task(struct bio *bio) { }
  #endif	/* CONFIG_BLK_CGROUP */
  
  #ifdef CONFIG_HIGHMEM
  /*
   * remember never ever reenable interrupts between a bvec_kmap_irq and
   * bvec_kunmap_irq!
   */
  static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
  {
  	unsigned long addr;
  
  	/*
  	 * might not be a highmem page, but the preempt/irq count
  	 * balancing is a lot nicer this way
  	 */
  	local_irq_save(*flags);
  	addr = (unsigned long) kmap_atomic(bvec->bv_page);
  
  	BUG_ON(addr & ~PAGE_MASK);
  
  	return (char *) addr + bvec->bv_offset;
  }
  
  static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
  {
  	unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
  
  	kunmap_atomic((void *) ptr);
  	local_irq_restore(*flags);
  }
  
  #else
  static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
  {
  	return page_address(bvec->bv_page) + bvec->bv_offset;
  }
  
  static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
  {
  	*flags = 0;
  }
  #endif
  
  static inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx,
  				   unsigned long *flags)
  {
  	return bvec_kmap_irq(bio_iovec_idx(bio, idx), flags);
  }
  #define __bio_kunmap_irq(buf, flags)	bvec_kunmap_irq(buf, flags)
  
  #define bio_kmap_irq(bio, flags) \
  	__bio_kmap_irq((bio), (bio)->bi_idx, (flags))
  #define bio_kunmap_irq(buf,flags)	__bio_kunmap_irq(buf, flags)
  
  /*
   * Check whether this bio carries any data or not. A NULL bio is allowed.
   */
  static inline bool bio_has_data(struct bio *bio)
  {
  	if (bio && bio->bi_vcnt)
  		return true;
  
  	return false;
  }
  
  static inline bool bio_is_rw(struct bio *bio)
  {
  	if (!bio_has_data(bio))
  		return false;
  
  	if (bio->bi_rw & REQ_WRITE_SAME)
  		return false;
  
  	return true;
  }
  
  static inline bool bio_mergeable(struct bio *bio)
  {
  	if (bio->bi_rw & REQ_NOMERGE_FLAGS)
  		return false;
  
  	return true;
  }
  
  /*
   * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
   *
   * A bio_list anchors a singly-linked list of bios chained through the bi_next
   * member of the bio.  The bio_list also caches the last list member to allow
   * fast access to the tail.
   */
  struct bio_list {
  	struct bio *head;
  	struct bio *tail;
  };
  
  static inline int bio_list_empty(const struct bio_list *bl)
  {
  	return bl->head == NULL;
  }
  
  static inline void bio_list_init(struct bio_list *bl)
  {
  	bl->head = bl->tail = NULL;
  }
  
  #define BIO_EMPTY_LIST	{ NULL, NULL }
  
  #define bio_list_for_each(bio, bl) \
  	for (bio = (bl)->head; bio; bio = bio->bi_next)
  
  static inline unsigned bio_list_size(const struct bio_list *bl)
  {
  	unsigned sz = 0;
  	struct bio *bio;
  
  	bio_list_for_each(bio, bl)
  		sz++;
  
  	return sz;
  }
  
  static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
  {
  	bio->bi_next = NULL;
  
  	if (bl->tail)
  		bl->tail->bi_next = bio;
  	else
  		bl->head = bio;
  
  	bl->tail = bio;
  }
  
  static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
  {
  	bio->bi_next = bl->head;
  
  	bl->head = bio;
  
  	if (!bl->tail)
  		bl->tail = bio;
  }
  
  static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
  {
  	if (!bl2->head)
  		return;
  
  	if (bl->tail)
  		bl->tail->bi_next = bl2->head;
  	else
  		bl->head = bl2->head;
  
  	bl->tail = bl2->tail;
  }
  
  static inline void bio_list_merge_head(struct bio_list *bl,
  				       struct bio_list *bl2)
  {
  	if (!bl2->head)
  		return;
  
  	if (bl->head)
  		bl2->tail->bi_next = bl->head;
  	else
  		bl->tail = bl2->tail;
  
  	bl->head = bl2->head;
  }
  
  static inline struct bio *bio_list_peek(struct bio_list *bl)
  {
  	return bl->head;
  }
  
  static inline struct bio *bio_list_pop(struct bio_list *bl)
  {
  	struct bio *bio = bl->head;
  
  	if (bio) {
  		bl->head = bl->head->bi_next;
  		if (!bl->head)
  			bl->tail = NULL;
  
  		bio->bi_next = NULL;
  	}
  
  	return bio;
  }
  
  static inline struct bio *bio_list_get(struct bio_list *bl)
  {
  	struct bio *bio = bl->head;
  
  	bl->head = bl->tail = NULL;
  
  	return bio;
  }
  
  /*
   * bio_set is used to allow other portions of the IO system to
   * allocate their own private memory pools for bio and iovec structures.
   * These memory pools in turn all allocate from the bio_slab
   * and the bvec_slabs[].
   */
  #define BIO_POOL_SIZE 2
  #define BIOVEC_NR_POOLS 6
  #define BIOVEC_MAX_IDX	(BIOVEC_NR_POOLS - 1)
  
  struct bio_set {
  	struct kmem_cache *bio_slab;
  	unsigned int front_pad;
  
  	mempool_t *bio_pool;
  	mempool_t *bvec_pool;
  #if defined(CONFIG_BLK_DEV_INTEGRITY)
  	mempool_t *bio_integrity_pool;
  	mempool_t *bvec_integrity_pool;
  #endif
  
  	/*
  	 * Deadlock avoidance for stacking block drivers: see comments in
  	 * bio_alloc_bioset() for details
  	 */
  	spinlock_t		rescue_lock;
  	struct bio_list		rescue_list;
  	struct work_struct	rescue_work;
  	struct workqueue_struct	*rescue_workqueue;
  };
  
  struct biovec_slab {
  	int nr_vecs;
  	char *name;
  	struct kmem_cache *slab;
  };
  
  /*
   * a small number of entries is fine, not going to be performance critical.
   * basically we just need to survive
   */
  #define BIO_SPLIT_ENTRIES 2
  
  #if defined(CONFIG_BLK_DEV_INTEGRITY)
  
  #define bip_vec_idx(bip, idx)	(&(bip->bip_vec[(idx)]))
  #define bip_vec(bip)		bip_vec_idx(bip, 0)
  
  #define __bip_for_each_vec(bvl, bip, i, start_idx)			\
  	for (bvl = bip_vec_idx((bip), (start_idx)), i = (start_idx);	\
  	     i < (bip)->bip_vcnt;					\
  	     bvl++, i++)
  
  #define bip_for_each_vec(bvl, bip, i)					\
  	__bip_for_each_vec(bvl, bip, i, (bip)->bip_idx)
  
  #define bio_for_each_integrity_vec(_bvl, _bio, _iter)			\
  	for_each_bio(_bio)						\
  		bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)
  
  #define bio_integrity(bio) (bio->bi_integrity != NULL)
  
  extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
  extern void bio_integrity_free(struct bio *);
  extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
  extern int bio_integrity_enabled(struct bio *bio);
  extern int bio_integrity_set_tag(struct bio *, void *, unsigned int);
  extern int bio_integrity_get_tag(struct bio *, void *, unsigned int);
  extern int bio_integrity_prep(struct bio *);
  extern void bio_integrity_endio(struct bio *, int);
  extern void bio_integrity_advance(struct bio *, unsigned int);
  extern void bio_integrity_trim(struct bio *, unsigned int, unsigned int);
  extern void bio_integrity_split(struct bio *, struct bio_pair *, int);
  extern int bio_integrity_clone(struct bio *, struct bio *, gfp_t);
  extern int bioset_integrity_create(struct bio_set *, int);
  extern void bioset_integrity_free(struct bio_set *);
  extern void bio_integrity_init(void);
  
  #else /* CONFIG_BLK_DEV_INTEGRITY */
  
  static inline int bio_integrity(struct bio *bio)
  {
  	return 0;
  }
  
  static inline int bio_integrity_enabled(struct bio *bio)
  {
  	return 0;
  }
  
  static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
  {
  	return 0;
  }
  
  static inline void bioset_integrity_free (struct bio_set *bs)
  {
  	return;
  }
  
  static inline int bio_integrity_prep(struct bio *bio)
  {
  	return 0;
  }
  
  static inline void bio_integrity_free(struct bio *bio)
  {
  	return;
  }
  
  static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
  				      gfp_t gfp_mask)
  {
  	return 0;
  }
  
  static inline void bio_integrity_split(struct bio *bio, struct bio_pair *bp,
  				       int sectors)
  {
  	return;
  }
  
  static inline void bio_integrity_advance(struct bio *bio,
  					 unsigned int bytes_done)
  {
  	return;
  }
  
  static inline void bio_integrity_trim(struct bio *bio, unsigned int offset,
  				      unsigned int sectors)
  {
  	return;
  }
  
  static inline void bio_integrity_init(void)
  {
  	return;
  }
  
  #endif /* CONFIG_BLK_DEV_INTEGRITY */
  
  #endif /* CONFIG_BLOCK */
  #endif /* __LINUX_BIO_H */
  