LXR linux/include/linux/bio.h

   1/*
   2 * 2.5 block I/O model
   3 *
   4 * Copyright (C) 2001 Jens Axboe <axboe@suse.de>
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License version 2 as
   8 * published by the Free Software Foundation.
   9 *
  10 * This program is distributed in the hope that it will be useful,
  11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public Licens
  17 * along with this program; if not, write to the Free Software
  18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
  19 */
  20#ifndef __LINUX_BIO_H
  21#define __LINUX_BIO_H
  22
  23#include <linux/highmem.h>
  24#include <linux/mempool.h>
  25#include <linux/ioprio.h>
  26
  27#ifdef CONFIG_BLOCK
  28
  29/* Platforms may set this to teach the BIO layer about IOMMU hardware. */
  30#include <asm/io.h>
  31
  32#if defined(BIO_VMERGE_MAX_SIZE) && defined(BIO_VMERGE_BOUNDARY)
  33#define BIOVEC_VIRT_START_SIZE(x) (bvec_to_phys(x) & (BIO_VMERGE_BOUNDARY - 1))
  34#define BIOVEC_VIRT_OVERSIZE(x) ((x) > BIO_VMERGE_MAX_SIZE)
  35#else
  36#define BIOVEC_VIRT_START_SIZE(x)       0
  37#define BIOVEC_VIRT_OVERSIZE(x)         0
  38#endif
  39
  40#ifndef BIO_VMERGE_BOUNDARY
  41#define BIO_VMERGE_BOUNDARY     0
  42#endif
  43
  44#define BIO_DEBUG
  45
  46#ifdef BIO_DEBUG
  47#define BIO_BUG_ON      BUG_ON
  48#else
  49#define BIO_BUG_ON
  50#endif
  51
  52#define BIO_MAX_PAGES           256
  53#define BIO_MAX_SIZE            (BIO_MAX_PAGES << PAGE_CACHE_SHIFT)
  54#define BIO_MAX_SECTORS         (BIO_MAX_SIZE >> 9)
  55
  56/*
  57 * was unsigned short, but we might as well be ready for > 64kB I/O pages
  58 */
  59struct bio_vec {
  60        struct page     *bv_page;
  61        unsigned int    bv_len;
  62        unsigned int    bv_offset;
  63};
  64
  65struct bio_set;
  66struct bio;
  67struct bio_integrity_payload;
  68typedef void (bio_end_io_t) (struct bio *, int);
  69typedef void (bio_destructor_t) (struct bio *);
  70
  71/*
  72 * main unit of I/O for the block layer and lower layers (ie drivers and
  73 * stacking drivers)
  74 */
  75struct bio {
  76        sector_t                bi_sector;      /* device address in 512 byte
  77                                                   sectors */
  78        struct bio              *bi_next;       /* request queue link */
  79        struct block_device     *bi_bdev;
  80        unsigned long           bi_flags;       /* status, command, etc */
  81        unsigned long           bi_rw;          /* bottom bits READ/WRITE,
  82                                                 * top bits priority
  83                                                 */
  84
  85        unsigned short          bi_vcnt;        /* how many bio_vec's */
  86        unsigned short          bi_idx;         /* current index into bvl_vec */
  87
  88        /* Number of segments in this BIO after
  89         * physical address coalescing is performed.
  90         */
  91        unsigned short          bi_phys_segments;
  92
  93        /* Number of segments after physical and DMA remapping
  94         * hardware coalescing is performed.
  95         */
  96        unsigned short          bi_hw_segments;
  97
  98        unsigned int            bi_size;        /* residual I/O count */
  99
 100        /*
 101         * To keep track of the max hw size, we account for the
 102         * sizes of the first and last virtually mergeable segments
 103         * in this bio
 104         */
 105        unsigned int            bi_hw_front_size;
 106        unsigned int            bi_hw_back_size;
 107
 108        unsigned int            bi_max_vecs;    /* max bvl_vecs we can hold */
 109
 110        struct bio_vec          *bi_io_vec;     /* the actual vec list */
 111
 112        bio_end_io_t            *bi_end_io;
 113        atomic_t                bi_cnt;         /* pin count */
 114
 115        void                    *bi_private;
 116#if defined(CONFIG_BLK_DEV_INTEGRITY)
 117        struct bio_integrity_payload *bi_integrity;  /* data integrity */
 118#endif
 119
 120        bio_destructor_t        *bi_destructor; /* destructor */
 121};
 122
 123/*
 124 * bio flags
 125 */
 126#define BIO_UPTODATE    0       /* ok after I/O completion */
 127#define BIO_RW_BLOCK    1       /* RW_AHEAD set, and read/write would block */
 128#define BIO_EOF         2       /* out-out-bounds error */
 129#define BIO_SEG_VALID   3       /* nr_hw_seg valid */
 130#define BIO_CLONED      4       /* doesn't own data */
 131#define BIO_BOUNCED     5       /* bio is a bounce bio */
 132#define BIO_USER_MAPPED 6       /* contains user pages */
 133#define BIO_EOPNOTSUPP  7       /* not supported */
 134#define bio_flagged(bio, flag)  ((bio)->bi_flags & (1 << (flag)))
 135
 136/*
 137 * top 4 bits of bio flags indicate the pool this bio came from
 138 */
 139#define BIO_POOL_BITS           (4)
 140#define BIO_POOL_OFFSET         (BITS_PER_LONG - BIO_POOL_BITS)
 141#define BIO_POOL_MASK           (1UL << BIO_POOL_OFFSET)
 142#define BIO_POOL_IDX(bio)       ((bio)->bi_flags >> BIO_POOL_OFFSET)    
 143
 144/*
 145 * bio bi_rw flags
 146 *
 147 * bit 0 -- read (not set) or write (set)
 148 * bit 1 -- rw-ahead when set
 149 * bit 2 -- barrier
 150 * bit 3 -- fail fast, don't want low level driver retries
 151 * bit 4 -- synchronous I/O hint: the block layer will unplug immediately
 152 */
 153#define BIO_RW          0
 154#define BIO_RW_AHEAD    1
 155#define BIO_RW_BARRIER  2
 156#define BIO_RW_FAILFAST 3
 157#define BIO_RW_SYNC     4
 158#define BIO_RW_META     5
 159
 160/*
 161 * upper 16 bits of bi_rw define the io priority of this bio
 162 */
 163#define BIO_PRIO_SHIFT  (8 * sizeof(unsigned long) - IOPRIO_BITS)
 164#define bio_prio(bio)   ((bio)->bi_rw >> BIO_PRIO_SHIFT)
 165#define bio_prio_valid(bio)     ioprio_valid(bio_prio(bio))
 166
 167#define bio_set_prio(bio, prio)         do {                    \
 168        WARN_ON(prio >= (1 << IOPRIO_BITS));                    \
 169        (bio)->bi_rw &= ((1UL << BIO_PRIO_SHIFT) - 1);          \
 170        (bio)->bi_rw |= ((unsigned long) (prio) << BIO_PRIO_SHIFT);     \
 171} while (0)
 172
 173/*
 174 * various member access, note that bio_data should of course not be used
 175 * on highmem page vectors
 176 */
 177#define bio_iovec_idx(bio, idx) (&((bio)->bi_io_vec[(idx)]))
 178#define bio_iovec(bio)          bio_iovec_idx((bio), (bio)->bi_idx)
 179#define bio_page(bio)           bio_iovec((bio))->bv_page
 180#define bio_offset(bio)         bio_iovec((bio))->bv_offset
 181#define bio_segments(bio)       ((bio)->bi_vcnt - (bio)->bi_idx)
 182#define bio_sectors(bio)        ((bio)->bi_size >> 9)
 183#define bio_barrier(bio)        ((bio)->bi_rw & (1 << BIO_RW_BARRIER))
 184#define bio_sync(bio)           ((bio)->bi_rw & (1 << BIO_RW_SYNC))
 185#define bio_failfast(bio)       ((bio)->bi_rw & (1 << BIO_RW_FAILFAST))
 186#define bio_rw_ahead(bio)       ((bio)->bi_rw & (1 << BIO_RW_AHEAD))
 187#define bio_rw_meta(bio)        ((bio)->bi_rw & (1 << BIO_RW_META))
 188#define bio_empty_barrier(bio)  (bio_barrier(bio) && !(bio)->bi_size)
 189
 190static inline unsigned int bio_cur_sectors(struct bio *bio)
 191{
 192        if (bio->bi_vcnt)
 193                return bio_iovec(bio)->bv_len >> 9;
 194
 195        return 0;
 196}
 197
 198static inline void *bio_data(struct bio *bio)
 199{
 200        if (bio->bi_vcnt)
 201                return page_address(bio_page(bio)) + bio_offset(bio);
 202
 203        return NULL;
 204}
 205
 206/*
 207 * will die
 208 */
 209#define bio_to_phys(bio)        (page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio)))
 210#define bvec_to_phys(bv)        (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
 211
 212/*
 213 * queues that have highmem support enabled may still need to revert to
 214 * PIO transfers occasionally and thus map high pages temporarily. For
 215 * permanent PIO fall back, user is probably better off disabling highmem
 216 * I/O completely on that queue (see ide-dma for example)
 217 */
 218#define __bio_kmap_atomic(bio, idx, kmtype)                             \
 219        (kmap_atomic(bio_iovec_idx((bio), (idx))->bv_page, kmtype) +    \
 220                bio_iovec_idx((bio), (idx))->bv_offset)
 221
 222#define __bio_kunmap_atomic(addr, kmtype) kunmap_atomic(addr, kmtype)
 223
 224/*
 225 * merge helpers etc
 226 */
 227
 228#define __BVEC_END(bio)         bio_iovec_idx((bio), (bio)->bi_vcnt - 1)
 229#define __BVEC_START(bio)       bio_iovec_idx((bio), (bio)->bi_idx)
 230
 231/*
 232 * allow arch override, for eg virtualized architectures (put in asm/io.h)
 233 */
 234#ifndef BIOVEC_PHYS_MERGEABLE
 235#define BIOVEC_PHYS_MERGEABLE(vec1, vec2)       \
 236        ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
 237#endif
 238
 239#define BIOVEC_VIRT_MERGEABLE(vec1, vec2)       \
 240        ((((bvec_to_phys((vec1)) + (vec1)->bv_len) | bvec_to_phys((vec2))) & (BIO_VMERGE_BOUNDARY - 1)) == 0)
 241#define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
 242        (((addr1) | (mask)) == (((addr2) - 1) | (mask)))
 243#define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
 244        __BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, (q)->seg_boundary_mask)
 245#define BIO_SEG_BOUNDARY(q, b1, b2) \
 246        BIOVEC_SEG_BOUNDARY((q), __BVEC_END((b1)), __BVEC_START((b2)))
 247
 248#define bio_io_error(bio) bio_endio((bio), -EIO)
 249
 250/*
 251 * drivers should not use the __ version unless they _really_ want to
 252 * run through the entire bio and not just pending pieces
 253 */
 254#define __bio_for_each_segment(bvl, bio, i, start_idx)                  \
 255        for (bvl = bio_iovec_idx((bio), (start_idx)), i = (start_idx);  \
 256             i < (bio)->bi_vcnt;                                        \
 257             bvl++, i++)
 258
 259#define bio_for_each_segment(bvl, bio, i)                               \
 260        __bio_for_each_segment(bvl, bio, i, (bio)->bi_idx)
 261
 262/*
 263 * get a reference to a bio, so it won't disappear. the intended use is
 264 * something like:
 265 *
 266 * bio_get(bio);
 267 * submit_bio(rw, bio);
 268 * if (bio->bi_flags ...)
 269 *      do_something
 270 * bio_put(bio);
 271 *
 272 * without the bio_get(), it could potentially complete I/O before submit_bio
 273 * returns. and then bio would be freed memory when if (bio->bi_flags ...)
 274 * runs
 275 */
 276#define bio_get(bio)    atomic_inc(&(bio)->bi_cnt)
 277
 278#if defined(CONFIG_BLK_DEV_INTEGRITY)
 279/*
 280 * bio integrity payload
 281 */
 282struct bio_integrity_payload {
 283        struct bio              *bip_bio;       /* parent bio */
 284        struct bio_vec          *bip_vec;       /* integrity data vector */
 285
 286        sector_t                bip_sector;     /* virtual start sector */
 287
 288        void                    *bip_buf;       /* generated integrity data */
 289        bio_end_io_t            *bip_end_io;    /* saved I/O completion fn */
 290
 291        int                     bip_error;      /* saved I/O error */
 292        unsigned int            bip_size;
 293
 294        unsigned short          bip_pool;       /* pool the ivec came from */
 295        unsigned short          bip_vcnt;       /* # of integrity bio_vecs */
 296        unsigned short          bip_idx;        /* current bip_vec index */
 297
 298        struct work_struct      bip_work;       /* I/O completion */
 299};
 300#endif /* CONFIG_BLK_DEV_INTEGRITY */
 301
 302/*
 303 * A bio_pair is used when we need to split a bio.
 304 * This can only happen for a bio that refers to just one
 305 * page of data, and in the unusual situation when the
 306 * page crosses a chunk/device boundary
 307 *
 308 * The address of the master bio is stored in bio1.bi_private
 309 * The address of the pool the pair was allocated from is stored
 310 *   in bio2.bi_private
 311 */
 312struct bio_pair {
 313        struct bio                      bio1, bio2;
 314        struct bio_vec                  bv1, bv2;
 315#if defined(CONFIG_BLK_DEV_INTEGRITY)
 316        struct bio_integrity_payload    bip1, bip2;
 317        struct bio_vec                  iv1, iv2;
 318#endif
 319        atomic_t                        cnt;
 320        int                             error;
 321};
 322extern struct bio_pair *bio_split(struct bio *bi, mempool_t *pool,
 323                                  int first_sectors);
 324extern mempool_t *bio_split_pool;
 325extern void bio_pair_release(struct bio_pair *dbio);
 326
 327extern struct bio_set *bioset_create(int, int);
 328extern void bioset_free(struct bio_set *);
 329
 330extern struct bio *bio_alloc(gfp_t, int);
 331extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
 332extern void bio_put(struct bio *);
 333extern void bio_free(struct bio *, struct bio_set *);
 334
 335extern void bio_endio(struct bio *, int);
 336struct request_queue;
 337extern int bio_phys_segments(struct request_queue *, struct bio *);
 338extern int bio_hw_segments(struct request_queue *, struct bio *);
 339
 340extern void __bio_clone(struct bio *, struct bio *);
 341extern struct bio *bio_clone(struct bio *, gfp_t);
 342
 343extern void bio_init(struct bio *);
 344
 345extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 346extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 347                           unsigned int, unsigned int);
 348extern int bio_get_nr_vecs(struct block_device *);
 349extern struct bio *bio_map_user(struct request_queue *, struct block_device *,
 350                                unsigned long, unsigned int, int);
 351struct sg_iovec;
 352extern struct bio *bio_map_user_iov(struct request_queue *,
 353                                    struct block_device *,
 354                                    struct sg_iovec *, int, int);
 355extern void bio_unmap_user(struct bio *);
 356extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
 357                                gfp_t);
 358extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
 359                                 gfp_t, int);
 360extern void bio_set_pages_dirty(struct bio *bio);
 361extern void bio_check_pages_dirty(struct bio *bio);
 362extern struct bio *bio_copy_user(struct request_queue *, unsigned long, unsigned int, int);
 363extern struct bio *bio_copy_user_iov(struct request_queue *, struct sg_iovec *,
 364                                     int, int);
 365extern int bio_uncopy_user(struct bio *);
 366void zero_fill_bio(struct bio *bio);
 367extern struct bio_vec *bvec_alloc_bs(gfp_t, int, unsigned long *, struct bio_set *);
 368extern unsigned int bvec_nr_vecs(unsigned short idx);
 369
 370/*
 371 * bio_set is used to allow other portions of the IO system to
 372 * allocate their own private memory pools for bio and iovec structures.
 373 * These memory pools in turn all allocate from the bio_slab
 374 * and the bvec_slabs[].
 375 */
 376#define BIO_POOL_SIZE 2
 377#define BIOVEC_NR_POOLS 6
 378
 379struct bio_set {
 380        mempool_t *bio_pool;
 381#if defined(CONFIG_BLK_DEV_INTEGRITY)
 382        mempool_t *bio_integrity_pool;
 383#endif
 384        mempool_t *bvec_pools[BIOVEC_NR_POOLS];
 385};
 386
 387struct biovec_slab {
 388        int nr_vecs;
 389        char *name;
 390        struct kmem_cache *slab;
 391};
 392
 393extern struct bio_set *fs_bio_set;
 394
 395/*
 396 * a small number of entries is fine, not going to be performance critical.
 397 * basically we just need to survive
 398 */
 399#define BIO_SPLIT_ENTRIES 2
 400
 401#ifdef CONFIG_HIGHMEM
 402/*
 403 * remember to add offset! and never ever reenable interrupts between a
 404 * bvec_kmap_irq and bvec_kunmap_irq!!
 405 *
 406 * This function MUST be inlined - it plays with the CPU interrupt flags.
 407 */
 408static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 409{
 410        unsigned long addr;
 411
 412        /*
 413         * might not be a highmem page, but the preempt/irq count
 414         * balancing is a lot nicer this way
 415         */
 416        local_irq_save(*flags);
 417        addr = (unsigned long) kmap_atomic(bvec->bv_page, KM_BIO_SRC_IRQ);
 418
 419        BUG_ON(addr & ~PAGE_MASK);
 420
 421        return (char *) addr + bvec->bv_offset;
 422}
 423
 424static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 425{
 426        unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
 427
 428        kunmap_atomic((void *) ptr, KM_BIO_SRC_IRQ);
 429        local_irq_restore(*flags);
 430}
 431
 432#else
 433#define bvec_kmap_irq(bvec, flags)      (page_address((bvec)->bv_page) + (bvec)->bv_offset)
 434#define bvec_kunmap_irq(buf, flags)     do { *(flags) = 0; } while (0)
 435#endif
 436
 437static inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx,
 438                                   unsigned long *flags)
 439{
 440        return bvec_kmap_irq(bio_iovec_idx(bio, idx), flags);
 441}
 442#define __bio_kunmap_irq(buf, flags)    bvec_kunmap_irq(buf, flags)
 443
 444#define bio_kmap_irq(bio, flags) \
 445        __bio_kmap_irq((bio), (bio)->bi_idx, (flags))
 446#define bio_kunmap_irq(buf,flags)       __bio_kunmap_irq(buf, flags)
 447
 448#if defined(CONFIG_BLK_DEV_INTEGRITY)
 449
 450#define bip_vec_idx(bip, idx)   (&(bip->bip_vec[(idx)]))
 451#define bip_vec(bip)            bip_vec_idx(bip, 0)
 452
 453#define __bip_for_each_vec(bvl, bip, i, start_idx)                      \
 454        for (bvl = bip_vec_idx((bip), (start_idx)), i = (start_idx);    \
 455             i < (bip)->bip_vcnt;                                       \
 456             bvl++, i++)
 457
 458#define bip_for_each_vec(bvl, bip, i)                                   \
 459        __bip_for_each_vec(bvl, bip, i, (bip)->bip_idx)
 460
 461static inline int bio_integrity(struct bio *bio)
 462{
 463#if defined(CONFIG_BLK_DEV_INTEGRITY)
 464        return bio->bi_integrity != NULL;
 465#else
 466        return 0;
 467#endif
 468}
 469
 470extern struct bio_integrity_payload *bio_integrity_alloc_bioset(struct bio *, gfp_t, unsigned int, struct bio_set *);
 471extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
 472extern void bio_integrity_free(struct bio *, struct bio_set *);
 473extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
 474extern int bio_integrity_enabled(struct bio *bio);
 475extern int bio_integrity_set_tag(struct bio *, void *, unsigned int);
 476extern int bio_integrity_get_tag(struct bio *, void *, unsigned int);
 477extern int bio_integrity_prep(struct bio *);
 478extern void bio_integrity_endio(struct bio *, int);
 479extern void bio_integrity_advance(struct bio *, unsigned int);
 480extern void bio_integrity_trim(struct bio *, unsigned int, unsigned int);
 481extern void bio_integrity_split(struct bio *, struct bio_pair *, int);
 482extern int bio_integrity_clone(struct bio *, struct bio *, struct bio_set *);
 483extern int bioset_integrity_create(struct bio_set *, int);
 484extern void bioset_integrity_free(struct bio_set *);
 485extern void bio_integrity_init_slab(void);
 486
 487#else /* CONFIG_BLK_DEV_INTEGRITY */
 488
 489#define bio_integrity(a)                (0)
 490#define bioset_integrity_create(a, b)   (0)
 491#define bio_integrity_prep(a)           (0)
 492#define bio_integrity_enabled(a)        (0)
 493#define bio_integrity_clone(a, b, c)    (0)
 494#define bioset_integrity_free(a)        do { } while (0)
 495#define bio_integrity_free(a, b)        do { } while (0)
 496#define bio_integrity_endio(a, b)       do { } while (0)
 497#define bio_integrity_advance(a, b)     do { } while (0)
 498#define bio_integrity_trim(a, b, c)     do { } while (0)
 499#define bio_integrity_split(a, b, c)    do { } while (0)
 500#define bio_integrity_set_tag(a, b, c)  do { } while (0)
 501#define bio_integrity_get_tag(a, b, c)  do { } while (0)
 502#define bio_integrity_init_slab(a)      do { } while (0)
 503
 504#endif /* CONFIG_BLK_DEV_INTEGRITY */
 505
 506#endif /* CONFIG_BLOCK */
 507#endif /* __LINUX_BIO_H */
 508