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/* Platforms may set this to teach the BIO layer about IOMMU hardware. */
  28#include <asm/io.h>
  29
  30#if defined(BIO_VMERGE_MAX_SIZE) && defined(BIO_VMERGE_BOUNDARY)
  31#define BIOVEC_VIRT_START_SIZE(x) (bvec_to_phys(x) & (BIO_VMERGE_BOUNDARY - 1))
  32#define BIOVEC_VIRT_OVERSIZE(x) ((x) > BIO_VMERGE_MAX_SIZE)
  33#else
  34#define BIOVEC_VIRT_START_SIZE(x)       0
  35#define BIOVEC_VIRT_OVERSIZE(x)         0
  36#endif
  37
  38#ifndef BIO_VMERGE_BOUNDARY
  39#define BIO_VMERGE_BOUNDARY     0
  40#endif
  41
  42#define BIO_DEBUG
  43
  44#ifdef BIO_DEBUG
  45#define BIO_BUG_ON      BUG_ON
  46#else
  47#define BIO_BUG_ON
  48#endif
  49
  50#define BIO_MAX_PAGES           256
  51#define BIO_MAX_SIZE            (BIO_MAX_PAGES << PAGE_CACHE_SHIFT)
  52#define BIO_MAX_SECTORS         (BIO_MAX_SIZE >> 9)
  53
  54/*
  55 * was unsigned short, but we might as well be ready for > 64kB I/O pages
  56 */
  57struct bio_vec {
  58        struct page     *bv_page;
  59        unsigned int    bv_len;
  60        unsigned int    bv_offset;
  61};
  62
  63struct bio_set;
  64struct bio;
  65typedef int (bio_end_io_t) (struct bio *, unsigned int, int);
  66typedef void (bio_destructor_t) (struct bio *);
  67
  68/*
  69 * main unit of I/O for the block layer and lower layers (ie drivers and
  70 * stacking drivers)
  71 */
  72struct bio {
  73        sector_t                bi_sector;
  74        struct bio              *bi_next;       /* request queue link */
  75        struct block_device     *bi_bdev;
  76        unsigned long           bi_flags;       /* status, command, etc */
  77        unsigned long           bi_rw;          /* bottom bits READ/WRITE,
  78                                                 * top bits priority
  79                                                 */
  80
  81        unsigned short          bi_vcnt;        /* how many bio_vec's */
  82        unsigned short          bi_idx;         /* current index into bvl_vec */
  83
  84        /* Number of segments in this BIO after
  85         * physical address coalescing is performed.
  86         */
  87        unsigned short          bi_phys_segments;
  88
  89        /* Number of segments after physical and DMA remapping
  90         * hardware coalescing is performed.
  91         */
  92        unsigned short          bi_hw_segments;
  93
  94        unsigned int            bi_size;        /* residual I/O count */
  95
  96        /*
  97         * To keep track of the max hw size, we account for the
  98         * sizes of the first and last virtually mergeable segments
  99         * in this bio
 100         */
 101        unsigned int            bi_hw_front_size;
 102        unsigned int            bi_hw_back_size;
 103
 104        unsigned int            bi_max_vecs;    /* max bvl_vecs we can hold */
 105
 106        struct bio_vec          *bi_io_vec;     /* the actual vec list */
 107
 108        bio_end_io_t            *bi_end_io;
 109        atomic_t                bi_cnt;         /* pin count */
 110
 111        void                    *bi_private;
 112
 113        bio_destructor_t        *bi_destructor; /* destructor */
 114};
 115
 116/*
 117 * bio flags
 118 */
 119#define BIO_UPTODATE    0       /* ok after I/O completion */
 120#define BIO_RW_BLOCK    1       /* RW_AHEAD set, and read/write would block */
 121#define BIO_EOF         2       /* out-out-bounds error */
 122#define BIO_SEG_VALID   3       /* nr_hw_seg valid */
 123#define BIO_CLONED      4       /* doesn't own data */
 124#define BIO_BOUNCED     5       /* bio is a bounce bio */
 125#define BIO_USER_MAPPED 6       /* contains user pages */
 126#define BIO_EOPNOTSUPP  7       /* not supported */
 127#define bio_flagged(bio, flag)  ((bio)->bi_flags & (1 << (flag)))
 128
 129/*
 130 * top 4 bits of bio flags indicate the pool this bio came from
 131 */
 132#define BIO_POOL_BITS           (4)
 133#define BIO_POOL_OFFSET         (BITS_PER_LONG - BIO_POOL_BITS)
 134#define BIO_POOL_MASK           (1UL << BIO_POOL_OFFSET)
 135#define BIO_POOL_IDX(bio)       ((bio)->bi_flags >> BIO_POOL_OFFSET)    
 136
 137/*
 138 * bio bi_rw flags
 139 *
 140 * bit 0 -- read (not set) or write (set)
 141 * bit 1 -- rw-ahead when set
 142 * bit 2 -- barrier
 143 * bit 3 -- fail fast, don't want low level driver retries
 144 * bit 4 -- synchronous I/O hint: the block layer will unplug immediately
 145 */
 146#define BIO_RW          0
 147#define BIO_RW_AHEAD    1
 148#define BIO_RW_BARRIER  2
 149#define BIO_RW_FAILFAST 3
 150#define BIO_RW_SYNC     4
 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_cur_sectors(bio)    (bio_iovec(bio)->bv_len >> 9)
 176#define bio_data(bio)           (page_address(bio_page((bio))) + bio_offset((bio)))
 177#define bio_barrier(bio)        ((bio)->bi_rw & (1 << BIO_RW_BARRIER))
 178#define bio_sync(bio)           ((bio)->bi_rw & (1 << BIO_RW_SYNC))
 179#define bio_failfast(bio)       ((bio)->bi_rw & (1 << BIO_RW_FAILFAST))
 180#define bio_rw_ahead(bio)       ((bio)->bi_rw & (1 << BIO_RW_AHEAD))
 181
 182/*
 183 * will die
 184 */
 185#define bio_to_phys(bio)        (page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio)))
 186#define bvec_to_phys(bv)        (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
 187
 188/*
 189 * queues that have highmem support enabled may still need to revert to
 190 * PIO transfers occasionally and thus map high pages temporarily. For
 191 * permanent PIO fall back, user is probably better off disabling highmem
 192 * I/O completely on that queue (see ide-dma for example)
 193 */
 194#define __bio_kmap_atomic(bio, idx, kmtype)                             \
 195        (kmap_atomic(bio_iovec_idx((bio), (idx))->bv_page, kmtype) +    \
 196                bio_iovec_idx((bio), (idx))->bv_offset)
 197
 198#define __bio_kunmap_atomic(addr, kmtype) kunmap_atomic(addr, kmtype)
 199
 200/*
 201 * merge helpers etc
 202 */
 203
 204#define __BVEC_END(bio)         bio_iovec_idx((bio), (bio)->bi_vcnt - 1)
 205#define __BVEC_START(bio)       bio_iovec_idx((bio), (bio)->bi_idx)
 206
 207/*
 208 * allow arch override, for eg virtualized architectures (put in asm/io.h)
 209 */
 210#ifndef BIOVEC_PHYS_MERGEABLE
 211#define BIOVEC_PHYS_MERGEABLE(vec1, vec2)       \
 212        ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
 213#endif
 214
 215#define BIOVEC_VIRT_MERGEABLE(vec1, vec2)       \
 216        ((((bvec_to_phys((vec1)) + (vec1)->bv_len) | bvec_to_phys((vec2))) & (BIO_VMERGE_BOUNDARY - 1)) == 0)
 217#define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
 218        (((addr1) | (mask)) == (((addr2) - 1) | (mask)))
 219#define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
 220        __BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, (q)->seg_boundary_mask)
 221#define BIO_SEG_BOUNDARY(q, b1, b2) \
 222        BIOVEC_SEG_BOUNDARY((q), __BVEC_END((b1)), __BVEC_START((b2)))
 223
 224#define bio_io_error(bio, bytes) bio_endio((bio), (bytes), -EIO)
 225
 226/*
 227 * drivers should not use the __ version unless they _really_ want to
 228 * run through the entire bio and not just pending pieces
 229 */
 230#define __bio_for_each_segment(bvl, bio, i, start_idx)                  \
 231        for (bvl = bio_iovec_idx((bio), (start_idx)), i = (start_idx);  \
 232             i < (bio)->bi_vcnt;                                        \
 233             bvl++, i++)
 234
 235#define bio_for_each_segment(bvl, bio, i)                               \
 236        __bio_for_each_segment(bvl, bio, i, (bio)->bi_idx)
 237
 238/*
 239 * get a reference to a bio, so it won't disappear. the intended use is
 240 * something like:
 241 *
 242 * bio_get(bio);
 243 * submit_bio(rw, bio);
 244 * if (bio->bi_flags ...)
 245 *      do_something
 246 * bio_put(bio);
 247 *
 248 * without the bio_get(), it could potentially complete I/O before submit_bio
 249 * returns. and then bio would be freed memory when if (bio->bi_flags ...)
 250 * runs
 251 */
 252#define bio_get(bio)    atomic_inc(&(bio)->bi_cnt)
 253
 254
 255/*
 256 * A bio_pair is used when we need to split a bio.
 257 * This can only happen for a bio that refers to just one
 258 * page of data, and in the unusual situation when the
 259 * page crosses a chunk/device boundary
 260 *
 261 * The address of the master bio is stored in bio1.bi_private
 262 * The address of the pool the pair was allocated from is stored
 263 *   in bio2.bi_private
 264 */
 265struct bio_pair {
 266        struct bio      bio1, bio2;
 267        struct bio_vec  bv1, bv2;
 268        atomic_t        cnt;
 269        int             error;
 270};
 271extern struct bio_pair *bio_split(struct bio *bi, mempool_t *pool,
 272                                  int first_sectors);
 273extern mempool_t *bio_split_pool;
 274extern void bio_pair_release(struct bio_pair *dbio);
 275
 276extern struct bio_set *bioset_create(int, int, int);
 277extern void bioset_free(struct bio_set *);
 278
 279extern struct bio *bio_alloc(gfp_t, int);
 280extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
 281extern void bio_put(struct bio *);
 282extern void bio_free(struct bio *, struct bio_set *);
 283
 284extern void bio_endio(struct bio *, unsigned int, int);
 285struct request_queue;
 286extern int bio_phys_segments(struct request_queue *, struct bio *);
 287extern int bio_hw_segments(struct request_queue *, struct bio *);
 288
 289extern void __bio_clone(struct bio *, struct bio *);
 290extern struct bio *bio_clone(struct bio *, gfp_t);
 291
 292extern void bio_init(struct bio *);
 293
 294extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 295extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 296                           unsigned int, unsigned int);
 297extern int bio_get_nr_vecs(struct block_device *);
 298extern struct bio *bio_map_user(struct request_queue *, struct block_device *,
 299                                unsigned long, unsigned int, int);
 300struct sg_iovec;
 301extern struct bio *bio_map_user_iov(struct request_queue *,
 302                                    struct block_device *,
 303                                    struct sg_iovec *, int, int);
 304extern void bio_unmap_user(struct bio *);
 305extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
 306                                gfp_t);
 307extern void bio_set_pages_dirty(struct bio *bio);
 308extern void bio_check_pages_dirty(struct bio *bio);
 309extern struct bio *bio_copy_user(struct request_queue *, unsigned long, unsigned int, int);
 310extern int bio_uncopy_user(struct bio *);
 311void zero_fill_bio(struct bio *bio);
 312
 313#ifdef CONFIG_HIGHMEM
 314/*
 315 * remember to add offset! and never ever reenable interrupts between a
 316 * bvec_kmap_irq and bvec_kunmap_irq!!
 317 *
 318 * This function MUST be inlined - it plays with the CPU interrupt flags.
 319 */
 320static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 321{
 322        unsigned long addr;
 323
 324        /*
 325         * might not be a highmem page, but the preempt/irq count
 326         * balancing is a lot nicer this way
 327         */
 328        local_irq_save(*flags);
 329        addr = (unsigned long) kmap_atomic(bvec->bv_page, KM_BIO_SRC_IRQ);
 330
 331        BUG_ON(addr & ~PAGE_MASK);
 332
 333        return (char *) addr + bvec->bv_offset;
 334}
 335
 336static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 337{
 338        unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
 339
 340        kunmap_atomic((void *) ptr, KM_BIO_SRC_IRQ);
 341        local_irq_restore(*flags);
 342}
 343
 344#else
 345#define bvec_kmap_irq(bvec, flags)      (page_address((bvec)->bv_page) + (bvec)->bv_offset)
 346#define bvec_kunmap_irq(buf, flags)     do { *(flags) = 0; } while (0)
 347#endif
 348
 349static inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx,
 350                                   unsigned long *flags)
 351{
 352        return bvec_kmap_irq(bio_iovec_idx(bio, idx), flags);
 353}
 354#define __bio_kunmap_irq(buf, flags)    bvec_kunmap_irq(buf, flags)
 355
 356#define bio_kmap_irq(bio, flags) \
 357        __bio_kmap_irq((bio), (bio)->bi_idx, (flags))
 358#define bio_kunmap_irq(buf,flags)       __bio_kunmap_irq(buf, flags)
 359
 360#endif /* __LINUX_BIO_H */
 361