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  */
  59 struct bio_vec {
  60         struct page     *bv_page;
  61         unsigned int    bv_len;
  62         unsigned int    bv_offset;
  63 };
  64
  65 struct bio_set;
  66 struct bio;
  67 typedef void (bio_end_io_t) (struct bio *, int);
  68 typedef void (bio_destructor_t) (struct bio *);
  69
  70 /*
  71  * main unit of I/O for the block layer and lower layers (ie drivers and
  72  * stacking drivers)
  73  */
  74 struct bio {
  75         sector_t                bi_sector;      /* device address in 512 byte
  76                                                    sectors */
  77         struct bio              *bi_next;       /* request queue link */
  78         struct block_device     *bi_bdev;
  79         unsigned long           bi_flags;       /* status, command, etc */
  80         unsigned long           bi_rw;          /* bottom bits READ/WRITE,
  81                                                  * top bits priority
  82                                                  */
  83
  84         unsigned short          bi_vcnt;        /* how many bio_vec's */
  85         unsigned short          bi_idx;         /* current index into bvl_vec */
  86
  87         /* Number of segments in this BIO after
  88          * physical address coalescing is performed.
  89          */
  90         unsigned short          bi_phys_segments;
  91
  92         /* Number of segments after physical and DMA remapping
  93          * hardware coalescing is performed.
  94          */
  95         unsigned short          bi_hw_segments;
  96
  97         unsigned int            bi_size;        /* residual I/O count */
  98
  99         /*
 100          * To keep track of the max hw size, we account for the
 101          * sizes of the first and last virtually mergeable segments
 102          * in this bio
 103          */
 104         unsigned int            bi_hw_front_size;
 105         unsigned int            bi_hw_back_size;
 106
 107         unsigned int            bi_max_vecs;    /* max bvl_vecs we can hold */
 108
 109         struct bio_vec          *bi_io_vec;     /* the actual vec list */
 110
 111         bio_end_io_t            *bi_end_io;
 112         atomic_t                bi_cnt;         /* pin count */
 113
 114         void                    *bi_private;
 115
 116         bio_destructor_t        *bi_destructor; /* destructor */
 117 };
 118
 119 /*
 120  * bio flags
 121  */
 122 #define BIO_UPTODATE    0       /* ok after I/O completion */
 123 #define BIO_RW_BLOCK    1       /* RW_AHEAD set, and read/write would block */
 124 #define BIO_EOF         2       /* out-out-bounds error */
 125 #define BIO_SEG_VALID   3       /* nr_hw_seg valid */
 126 #define BIO_CLONED      4       /* doesn't own data */
 127 #define BIO_BOUNCED     5       /* bio is a bounce bio */
 128 #define BIO_USER_MAPPED 6       /* contains user pages */
 129 #define BIO_EOPNOTSUPP  7       /* not supported */
 130 #define bio_flagged(bio, flag)  ((bio)->bi_flags & (1 << (flag)))
 131
 132 /*
 133  * top 4 bits of bio flags indicate the pool this bio came from
 134  */
 135 #define BIO_POOL_BITS           (4)
 136 #define BIO_POOL_OFFSET         (BITS_PER_LONG - BIO_POOL_BITS)
 137 #define BIO_POOL_MASK           (1UL << BIO_POOL_OFFSET)
 138 #define BIO_POOL_IDX(bio)       ((bio)->bi_flags >> BIO_POOL_OFFSET)
 139
 140 /*
 141  * bio bi_rw flags
 142  *
 143  * bit 0 -- read (not set) or write (set)
 144  * bit 1 -- rw-ahead when set
 145  * bit 2 -- barrier
 146  * bit 3 -- fail fast, don't want low level driver retries
 147  * bit 4 -- synchronous I/O hint: the block layer will unplug immediately
 148  */
 149 #define BIO_RW          0
 150 #define BIO_RW_AHEAD    1
 151 #define BIO_RW_BARRIER  2
 152 #define BIO_RW_FAILFAST 3
 153 #define BIO_RW_SYNC     4
 154 #define BIO_RW_META     5
 155
 156 /*
 157  * upper 16 bits of bi_rw define the io priority of this bio
 158  */
 159 #define BIO_PRIO_SHIFT  (8 * sizeof(unsigned long) - IOPRIO_BITS)
 160 #define bio_prio(bio)   ((bio)->bi_rw >> BIO_PRIO_SHIFT)
 161 #define bio_prio_valid(bio)     ioprio_valid(bio_prio(bio))
 162
 163 #define bio_set_prio(bio, prio)         do {                    \
 164         WARN_ON(prio >= (1 << IOPRIO_BITS));                    \
 165         (bio)->bi_rw &= ((1UL << BIO_PRIO_SHIFT) - 1);          \
 166         (bio)->bi_rw |= ((unsigned long) (prio) << BIO_PRIO_SHIFT);     \
 167 } while (0)
 168
 169 /*
 170  * various member access, note that bio_data should of course not be used
 171  * on highmem page vectors
 172  */
 173 #define bio_iovec_idx(bio, idx) (&((bio)->bi_io_vec[(idx)]))
 174 #define bio_iovec(bio)          bio_iovec_idx((bio), (bio)->bi_idx)
 175 #define bio_page(bio)           bio_iovec((bio))->bv_page
 176 #define bio_offset(bio)         bio_iovec((bio))->bv_offset
 177 #define bio_segments(bio)       ((bio)->bi_vcnt - (bio)->bi_idx)
 178 #define bio_sectors(bio)        ((bio)->bi_size >> 9)
 179 #define bio_barrier(bio)        ((bio)->bi_rw & (1 << BIO_RW_BARRIER))
 180 #define bio_sync(bio)           ((bio)->bi_rw & (1 << BIO_RW_SYNC))
 181 #define bio_failfast(bio)       ((bio)->bi_rw & (1 << BIO_RW_FAILFAST))
 182 #define bio_rw_ahead(bio)       ((bio)->bi_rw & (1 << BIO_RW_AHEAD))
 183 #define bio_rw_meta(bio)        ((bio)->bi_rw & (1 << BIO_RW_META))
 184 #define bio_empty_barrier(bio)  (bio_barrier(bio) && !(bio)->bi_size)
 185
 186 static inline unsigned int bio_cur_sectors(struct bio *bio)
 187 {
 188         if (bio->bi_vcnt)
 189                 return bio_iovec(bio)->bv_len >> 9;
 190
 191         return 0;
 192 }
 193
 194 static inline void *bio_data(struct bio *bio)
 195 {
 196         if (bio->bi_vcnt)
 197                 return page_address(bio_page(bio)) + bio_offset(bio);
 198
 199         return NULL;
 200 }
 201
 202 /*
 203  * will die
 204  */
 205 #define bio_to_phys(bio)        (page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio)))
 206 #define bvec_to_phys(bv)        (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
 207
 208 /*
 209  * queues that have highmem support enabled may still need to revert to
 210  * PIO transfers occasionally and thus map high pages temporarily. For
 211  * permanent PIO fall back, user is probably better off disabling highmem
 212  * I/O completely on that queue (see ide-dma for example)
 213  */
 214 #define __bio_kmap_atomic(bio, idx, kmtype)                             \
 215         (kmap_atomic(bio_iovec_idx((bio), (idx))->bv_page, kmtype) +    \
 216                 bio_iovec_idx((bio), (idx))->bv_offset)
 217
 218 #define __bio_kunmap_atomic(addr, kmtype) kunmap_atomic(addr, kmtype)
 219
 220 /*
 221  * merge helpers etc
 222  */
 223
 224 #define __BVEC_END(bio)         bio_iovec_idx((bio), (bio)->bi_vcnt - 1)
 225 #define __BVEC_START(bio)       bio_iovec_idx((bio), (bio)->bi_idx)
 226
 227 /*
 228  * allow arch override, for eg virtualized architectures (put in asm/io.h)
 229  */
 230 #ifndef BIOVEC_PHYS_MERGEABLE
 231 #define BIOVEC_PHYS_MERGEABLE(vec1, vec2)       \
 232         ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
 233 #endif
 234
 235 #define BIOVEC_VIRT_MERGEABLE(vec1, vec2)       \
 236         ((((bvec_to_phys((vec1)) + (vec1)->bv_len) | bvec_to_phys((vec2))) & (BIO_VMERGE_BOUNDARY - 1)) == 0)
 237 #define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
 238         (((addr1) | (mask)) == (((addr2) - 1) | (mask)))
 239 #define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
 240         __BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, (q)->seg_boundary_mask)
 241 #define BIO_SEG_BOUNDARY(q, b1, b2) \
 242         BIOVEC_SEG_BOUNDARY((q), __BVEC_END((b1)), __BVEC_START((b2)))
 243
 244 #define bio_io_error(bio) bio_endio((bio), -EIO)
 245
 246 /*
 247  * drivers should not use the __ version unless they _really_ want to
 248  * run through the entire bio and not just pending pieces
 249  */
 250 #define __bio_for_each_segment(bvl, bio, i, start_idx)                  \
 251         for (bvl = bio_iovec_idx((bio), (start_idx)), i = (start_idx);  \
 252              i < (bio)->bi_vcnt;                                        \
 253              bvl++, i++)
 254
 255 #define bio_for_each_segment(bvl, bio, i)                               \
 256         __bio_for_each_segment(bvl, bio, i, (bio)->bi_idx)
 257
 258 /*
 259  * get a reference to a bio, so it won't disappear. the intended use is
 260  * something like:
 261  *
 262  * bio_get(bio);
 263  * submit_bio(rw, bio);
 264  * if (bio->bi_flags ...)
 265  *      do_something
 266  * bio_put(bio);
 267  *
 268  * without the bio_get(), it could potentially complete I/O before submit_bio
 269  * returns. and then bio would be freed memory when if (bio->bi_flags ...)
 270  * runs
 271  */
 272 #define bio_get(bio)    atomic_inc(&(bio)->bi_cnt)
 273
 274
 275 /*
 276  * A bio_pair is used when we need to split a bio.
 277  * This can only happen for a bio that refers to just one
 278  * page of data, and in the unusual situation when the
 279  * page crosses a chunk/device boundary
 280  *
 281  * The address of the master bio is stored in bio1.bi_private
 282  * The address of the pool the pair was allocated from is stored
 283  *   in bio2.bi_private
 284  */
 285 struct bio_pair {
 286         struct bio      bio1, bio2;
 287         struct bio_vec  bv1, bv2;
 288         atomic_t        cnt;
 289         int             error;
 290 };
 291 extern struct bio_pair *bio_split(struct bio *bi, mempool_t *pool,
 292                                   int first_sectors);
 293 extern mempool_t *bio_split_pool;
 294 extern void bio_pair_release(struct bio_pair *dbio);
 295
 296 extern struct bio_set *bioset_create(int, int);
 297 extern void bioset_free(struct bio_set *);
 298
 299 extern struct bio *bio_alloc(gfp_t, int);
 300 extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
 301 extern void bio_put(struct bio *);
 302 extern void bio_free(struct bio *, struct bio_set *);
 303
 304 extern void bio_endio(struct bio *, int);
 305 struct request_queue;
 306 extern int bio_phys_segments(struct request_queue *, struct bio *);
 307 extern int bio_hw_segments(struct request_queue *, struct bio *);
 308
 309 extern void __bio_clone(struct bio *, struct bio *);
 310 extern struct bio *bio_clone(struct bio *, gfp_t);
 311
 312 extern void bio_init(struct bio *);
 313
 314 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 315 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 316                            unsigned int, unsigned int);
 317 extern int bio_get_nr_vecs(struct block_device *);
 318 extern struct bio *bio_map_user(struct request_queue *, struct block_device *,
 319                                 unsigned long, unsigned int, int);
 320 struct sg_iovec;
 321 extern struct bio *bio_map_user_iov(struct request_queue *,
 322                                     struct block_device *,
 323                                     struct sg_iovec *, int, int);
 324 extern void bio_unmap_user(struct bio *);
 325 extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
 326                                 gfp_t);
 327 extern void bio_set_pages_dirty(struct bio *bio);
 328 extern void bio_check_pages_dirty(struct bio *bio);
 329 extern struct bio *bio_copy_user(struct request_queue *, unsigned long, unsigned int, int);
 330 extern int bio_uncopy_user(struct bio *);
 331 void zero_fill_bio(struct bio *bio);
 332
 333 #ifdef CONFIG_HIGHMEM
 334 /*
 335  * remember to add offset! and never ever reenable interrupts between a
 336  * bvec_kmap_irq and bvec_kunmap_irq!!
 337  *
 338  * This function MUST be inlined - it plays with the CPU interrupt flags.
 339  */
 340 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 341 {
 342         unsigned long addr;
 343
 344         /*
 345          * might not be a highmem page, but the preempt/irq count
 346          * balancing is a lot nicer this way
 347          */
 348         local_irq_save(*flags);
 349         addr = (unsigned long) kmap_atomic(bvec->bv_page, KM_BIO_SRC_IRQ);
 350
 351         BUG_ON(addr & ~PAGE_MASK);
 352
 353         return (char *) addr + bvec->bv_offset;
 354 }
 355
 356 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 357 {
 358         unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
 359
 360         kunmap_atomic((void *) ptr, KM_BIO_SRC_IRQ);
 361         local_irq_restore(*flags);
 362 }
 363
 364 #else
 365 #define bvec_kmap_irq(bvec, flags)      (page_address((bvec)->bv_page) + (bvec)->bv_offset)
 366 #define bvec_kunmap_irq(buf, flags)     do { *(flags) = 0; } while (0)
 367 #endif
 368
 369 static inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx,
 370                                    unsigned long *flags)
 371 {
 372         return bvec_kmap_irq(bio_iovec_idx(bio, idx), flags);
 373 }
 374 #define __bio_kunmap_irq(buf, flags)    bvec_kunmap_irq(buf, flags)
 375
 376 #define bio_kmap_irq(bio, flags) \
 377         __bio_kmap_irq((bio), (bio)->bi_idx, (flags))
 378 #define bio_kunmap_irq(buf,flags)       __bio_kunmap_irq(buf, flags)
 379
 380 #endif /* CONFIG_BLOCK */
 381 #endif /* __LINUX_BIO_H */