1 /* 2 * 2.5 block I/O model 3 * 4 * Copyright (C) 2001 Jens Axboe <[email protected]> 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 */ 57 struct bio_vec { 58 struct page *bv_page; 59 unsigned int bv_len; 60 unsigned int bv_offset; 61 }; 62 63 struct bio_set; 64 struct bio; 65 typedef int (bio_end_io_t) (struct bio *, unsigned int, int); 66 typedef 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 */ 72 struct 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 struct bio_set *bi_set; /* memory pools set */ 115 }; 116 117 /* 118 * bio flags 119 */ 120 #define BIO_UPTODATE 0 /* ok after I/O completion */ 121 #define BIO_RW_BLOCK 1 /* RW_AHEAD set, and read/write would block */ 122 #define BIO_EOF 2 /* out-out-bounds error */ 123 #define BIO_SEG_VALID 3 /* nr_hw_seg valid */ 124 #define BIO_CLONED 4 /* doesn't own data */ 125 #define BIO_BOUNCED 5 /* bio is a bounce bio */ 126 #define BIO_USER_MAPPED 6 /* contains user pages */ 127 #define BIO_EOPNOTSUPP 7 /* not supported */ 128 #define bio_flagged(bio, flag) ((bio)->bi_flags & (1 << (flag))) 129 130 /* 131 * top 4 bits of bio flags indicate the pool this bio came from 132 */ 133 #define BIO_POOL_BITS (4) 134 #define BIO_POOL_OFFSET (BITS_PER_LONG - BIO_POOL_BITS) 135 #define BIO_POOL_MASK (1UL << BIO_POOL_OFFSET) 136 #define BIO_POOL_IDX(bio) ((bio)->bi_flags >> BIO_POOL_OFFSET) 137 138 /* 139 * bio bi_rw flags 140 * 141 * bit 0 -- read (not set) or write (set) 142 * bit 1 -- rw-ahead when set 143 * bit 2 -- barrier 144 * bit 3 -- fail fast, don't want low level driver retries 145 * bit 4 -- synchronous I/O hint: the block layer will unplug immediately 146 */ 147 #define BIO_RW 0 148 #define BIO_RW_AHEAD 1 149 #define BIO_RW_BARRIER 2 150 #define BIO_RW_FAILFAST 3 151 #define BIO_RW_SYNC 4 152 153 /* 154 * upper 16 bits of bi_rw define the io priority of this bio 155 */ 156 #define BIO_PRIO_SHIFT (8 * sizeof(unsigned long) - IOPRIO_BITS) 157 #define bio_prio(bio) ((bio)->bi_rw >> BIO_PRIO_SHIFT) 158 #define bio_prio_valid(bio) ioprio_valid(bio_prio(bio)) 159 160 #define bio_set_prio(bio, prio) do { \ 161 WARN_ON(prio >= (1 << IOPRIO_BITS)); \ 162 (bio)->bi_rw &= ((1UL << BIO_PRIO_SHIFT) - 1); \ 163 (bio)->bi_rw |= ((unsigned long) (prio) << BIO_PRIO_SHIFT); \ 164 } while (0) 165 166 /* 167 * various member access, note that bio_data should of course not be used 168 * on highmem page vectors 169 */ 170 #define bio_iovec_idx(bio, idx) (&((bio)->bi_io_vec[(idx)])) 171 #define bio_iovec(bio) bio_iovec_idx((bio), (bio)->bi_idx) 172 #define bio_page(bio) bio_iovec((bio))->bv_page 173 #define bio_offset(bio) bio_iovec((bio))->bv_offset 174 #define bio_segments(bio) ((bio)->bi_vcnt - (bio)->bi_idx) 175 #define bio_sectors(bio) ((bio)->bi_size >> 9) 176 #define bio_cur_sectors(bio) (bio_iovec(bio)->bv_len >> 9) 177 #define bio_data(bio) (page_address(bio_page((bio))) + bio_offset((bio))) 178 #define bio_barrier(bio) ((bio)->bi_rw & (1 << BIO_RW_BARRIER)) 179 #define bio_sync(bio) ((bio)->bi_rw & (1 << BIO_RW_SYNC)) 180 #define bio_failfast(bio) ((bio)->bi_rw & (1 << BIO_RW_FAILFAST)) 181 #define bio_rw_ahead(bio) ((bio)->bi_rw & (1 << BIO_RW_AHEAD)) 182 183 /* 184 * will die 185 */ 186 #define bio_to_phys(bio) (page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio))) 187 #define bvec_to_phys(bv) (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset) 188 189 /* 190 * queues that have highmem support enabled may still need to revert to 191 * PIO transfers occasionally and thus map high pages temporarily. For 192 * permanent PIO fall back, user is probably better off disabling highmem 193 * I/O completely on that queue (see ide-dma for example) 194 */ 195 #define __bio_kmap_atomic(bio, idx, kmtype) \ 196 (kmap_atomic(bio_iovec_idx((bio), (idx))->bv_page, kmtype) + \ 197 bio_iovec_idx((bio), (idx))->bv_offset) 198 199 #define __bio_kunmap_atomic(addr, kmtype) kunmap_atomic(addr, kmtype) 200 201 /* 202 * merge helpers etc 203 */ 204 205 #define __BVEC_END(bio) bio_iovec_idx((bio), (bio)->bi_vcnt - 1) 206 #define __BVEC_START(bio) bio_iovec_idx((bio), (bio)->bi_idx) 207 208 /* 209 * allow arch override, for eg virtualized architectures (put in asm/io.h) 210 */ 211 #ifndef BIOVEC_PHYS_MERGEABLE 212 #define BIOVEC_PHYS_MERGEABLE(vec1, vec2) \ 213 ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2))) 214 #endif 215 216 #define BIOVEC_VIRT_MERGEABLE(vec1, vec2) \ 217 ((((bvec_to_phys((vec1)) + (vec1)->bv_len) | bvec_to_phys((vec2))) & (BIO_VMERGE_BOUNDARY - 1)) == 0) 218 #define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \ 219 (((addr1) | (mask)) == (((addr2) - 1) | (mask))) 220 #define BIOVEC_SEG_BOUNDARY(q, b1, b2) \ 221 __BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, (q)->seg_boundary_mask) 222 #define BIO_SEG_BOUNDARY(q, b1, b2) \ 223 BIOVEC_SEG_BOUNDARY((q), __BVEC_END((b1)), __BVEC_START((b2))) 224 225 #define bio_io_error(bio, bytes) bio_endio((bio), (bytes), -EIO) 226 227 /* 228 * drivers should not use the __ version unless they _really_ want to 229 * run through the entire bio and not just pending pieces 230 */ 231 #define __bio_for_each_segment(bvl, bio, i, start_idx) \ 232 for (bvl = bio_iovec_idx((bio), (start_idx)), i = (start_idx); \ 233 i < (bio)->bi_vcnt; \ 234 bvl++, i++) 235 236 #define bio_for_each_segment(bvl, bio, i) \ 237 __bio_for_each_segment(bvl, bio, i, (bio)->bi_idx) 238 239 /* 240 * get a reference to a bio, so it won't disappear. the intended use is 241 * something like: 242 * 243 * bio_get(bio); 244 * submit_bio(rw, bio); 245 * if (bio->bi_flags ...) 246 * do_something 247 * bio_put(bio); 248 * 249 * without the bio_get(), it could potentially complete I/O before submit_bio 250 * returns. and then bio would be freed memory when if (bio->bi_flags ...) 251 * runs 252 */ 253 #define bio_get(bio) atomic_inc(&(bio)->bi_cnt) 254 255 256 /* 257 * A bio_pair is used when we need to split a bio. 258 * This can only happen for a bio that refers to just one 259 * page of data, and in the unusual situation when the 260 * page crosses a chunk/device boundary 261 * 262 * The address of the master bio is stored in bio1.bi_private 263 * The address of the pool the pair was allocated from is stored 264 * in bio2.bi_private 265 */ 266 struct bio_pair { 267 struct bio bio1, bio2; 268 struct bio_vec bv1, bv2; 269 atomic_t cnt; 270 int error; 271 }; 272 extern struct bio_pair *bio_split(struct bio *bi, mempool_t *pool, 273 int first_sectors); 274 extern mempool_t *bio_split_pool; 275 extern void bio_pair_release(struct bio_pair *dbio); 276 277 extern struct bio_set *bioset_create(int, int, int); 278 extern void bioset_free(struct bio_set *); 279 280 extern struct bio *bio_alloc(unsigned int __nocast, int); 281 extern struct bio *bio_alloc_bioset(unsigned int __nocast, int, struct bio_set *); 282 extern void bio_put(struct bio *); 283 284 extern void bio_endio(struct bio *, unsigned int, int); 285 struct request_queue; 286 extern int bio_phys_segments(struct request_queue *, struct bio *); 287 extern int bio_hw_segments(struct request_queue *, struct bio *); 288 289 extern void __bio_clone(struct bio *, struct bio *); 290 extern struct bio *bio_clone(struct bio *, unsigned int __nocast); 291 292 extern void bio_init(struct bio *); 293 294 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int); 295 extern int bio_get_nr_vecs(struct block_device *); 296 extern struct bio *bio_map_user(struct request_queue *, struct block_device *, 297 unsigned long, unsigned int, int); 298 extern void bio_unmap_user(struct bio *); 299 extern void bio_set_pages_dirty(struct bio *bio); 300 extern void bio_check_pages_dirty(struct bio *bio); 301 extern struct bio *bio_copy_user(struct request_queue *, unsigned long, unsigned int, int); 302 extern int bio_uncopy_user(struct bio *); 303 void zero_fill_bio(struct bio *bio); 304 305 #ifdef CONFIG_HIGHMEM 306 /* 307 * remember to add offset! and never ever reenable interrupts between a 308 * bvec_kmap_irq and bvec_kunmap_irq!! 309 * 310 * This function MUST be inlined - it plays with the CPU interrupt flags. 311 * Hence the `extern inline'. 312 */ 313 extern inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags) 314 { 315 unsigned long addr; 316 317 /* 318 * might not be a highmem page, but the preempt/irq count 319 * balancing is a lot nicer this way 320 */ 321 local_irq_save(*flags); 322 addr = (unsigned long) kmap_atomic(bvec->bv_page, KM_BIO_SRC_IRQ); 323 324 BUG_ON(addr & ~PAGE_MASK); 325 326 return (char *) addr + bvec->bv_offset; 327 } 328 329 extern inline void bvec_kunmap_irq(char *buffer, unsigned long *flags) 330 { 331 unsigned long ptr = (unsigned long) buffer & PAGE_MASK; 332 333 kunmap_atomic((void *) ptr, KM_BIO_SRC_IRQ); 334 local_irq_restore(*flags); 335 } 336 337 #else 338 #define bvec_kmap_irq(bvec, flags) (page_address((bvec)->bv_page) + (bvec)->bv_offset) 339 #define bvec_kunmap_irq(buf, flags) do { *(flags) = 0; } while (0) 340 #endif 341 342 extern inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx, 343 unsigned long *flags) 344 { 345 return bvec_kmap_irq(bio_iovec_idx(bio, idx), flags); 346 } 347 #define __bio_kunmap_irq(buf, flags) bvec_kunmap_irq(buf, flags) 348 349 #define bio_kmap_irq(bio, flags) \ 350 __bio_kmap_irq((bio), (bio)->bi_idx, (flags)) 351 #define bio_kunmap_irq(buf,flags) __bio_kunmap_irq(buf, flags) 352 353 #endif /* __LINUX_BIO_H */ 354