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