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 #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_cur_sectors(bio) (bio_iovec(bio)->bv_len >> 9) 180 #define bio_data(bio) (page_address(bio_page((bio))) + bio_offset((bio))) 181 #define bio_barrier(bio) ((bio)->bi_rw & (1 << BIO_RW_BARRIER)) 182 #define bio_sync(bio) ((bio)->bi_rw & (1 << BIO_RW_SYNC)) 183 #define bio_failfast(bio) ((bio)->bi_rw & (1 << BIO_RW_FAILFAST)) 184 #define bio_rw_ahead(bio) ((bio)->bi_rw & (1 << BIO_RW_AHEAD)) 185 #define bio_rw_meta(bio) ((bio)->bi_rw & (1 << BIO_RW_META)) 186 187 /* 188 * will die 189 */ 190 #define bio_to_phys(bio) (page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio))) 191 #define bvec_to_phys(bv) (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset) 192 193 /* 194 * queues that have highmem support enabled may still need to revert to 195 * PIO transfers occasionally and thus map high pages temporarily. For 196 * permanent PIO fall back, user is probably better off disabling highmem 197 * I/O completely on that queue (see ide-dma for example) 198 */ 199 #define __bio_kmap_atomic(bio, idx, kmtype) \ 200 (kmap_atomic(bio_iovec_idx((bio), (idx))->bv_page, kmtype) + \ 201 bio_iovec_idx((bio), (idx))->bv_offset) 202 203 #define __bio_kunmap_atomic(addr, kmtype) kunmap_atomic(addr, kmtype) 204 205 /* 206 * merge helpers etc 207 */ 208 209 #define __BVEC_END(bio) bio_iovec_idx((bio), (bio)->bi_vcnt - 1) 210 #define __BVEC_START(bio) bio_iovec_idx((bio), (bio)->bi_idx) 211 212 /* 213 * allow arch override, for eg virtualized architectures (put in asm/io.h) 214 */ 215 #ifndef BIOVEC_PHYS_MERGEABLE 216 #define BIOVEC_PHYS_MERGEABLE(vec1, vec2) \ 217 ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2))) 218 #endif 219 220 #define BIOVEC_VIRT_MERGEABLE(vec1, vec2) \ 221 ((((bvec_to_phys((vec1)) + (vec1)->bv_len) | bvec_to_phys((vec2))) & (BIO_VMERGE_BOUNDARY - 1)) == 0) 222 #define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \ 223 (((addr1) | (mask)) == (((addr2) - 1) | (mask))) 224 #define BIOVEC_SEG_BOUNDARY(q, b1, b2) \ 225 __BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, (q)->seg_boundary_mask) 226 #define BIO_SEG_BOUNDARY(q, b1, b2) \ 227 BIOVEC_SEG_BOUNDARY((q), __BVEC_END((b1)), __BVEC_START((b2))) 228 229 #define bio_io_error(bio) bio_endio((bio), -EIO) 230 231 /* 232 * drivers should not use the __ version unless they _really_ want to 233 * run through the entire bio and not just pending pieces 234 */ 235 #define __bio_for_each_segment(bvl, bio, i, start_idx) \ 236 for (bvl = bio_iovec_idx((bio), (start_idx)), i = (start_idx); \ 237 i < (bio)->bi_vcnt; \ 238 bvl++, i++) 239 240 #define bio_for_each_segment(bvl, bio, i) \ 241 __bio_for_each_segment(bvl, bio, i, (bio)->bi_idx) 242 243 /* 244 * get a reference to a bio, so it won't disappear. the intended use is 245 * something like: 246 * 247 * bio_get(bio); 248 * submit_bio(rw, bio); 249 * if (bio->bi_flags ...) 250 * do_something 251 * bio_put(bio); 252 * 253 * without the bio_get(), it could potentially complete I/O before submit_bio 254 * returns. and then bio would be freed memory when if (bio->bi_flags ...) 255 * runs 256 */ 257 #define bio_get(bio) atomic_inc(&(bio)->bi_cnt) 258 259 260 /* 261 * A bio_pair is used when we need to split a bio. 262 * This can only happen for a bio that refers to just one 263 * page of data, and in the unusual situation when the 264 * page crosses a chunk/device boundary 265 * 266 * The address of the master bio is stored in bio1.bi_private 267 * The address of the pool the pair was allocated from is stored 268 * in bio2.bi_private 269 */ 270 struct bio_pair { 271 struct bio bio1, bio2; 272 struct bio_vec bv1, bv2; 273 atomic_t cnt; 274 int error; 275 }; 276 extern struct bio_pair *bio_split(struct bio *bi, mempool_t *pool, 277 int first_sectors); 278 extern mempool_t *bio_split_pool; 279 extern void bio_pair_release(struct bio_pair *dbio); 280 281 extern struct bio_set *bioset_create(int, int); 282 extern void bioset_free(struct bio_set *); 283 284 extern struct bio *bio_alloc(gfp_t, int); 285 extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *); 286 extern void bio_put(struct bio *); 287 extern void bio_free(struct bio *, struct bio_set *); 288 289 extern void bio_endio(struct bio *, int); 290 struct request_queue; 291 extern int bio_phys_segments(struct request_queue *, struct bio *); 292 extern int bio_hw_segments(struct request_queue *, struct bio *); 293 294 extern void __bio_clone(struct bio *, struct bio *); 295 extern struct bio *bio_clone(struct bio *, gfp_t); 296 297 extern void bio_init(struct bio *); 298 299 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int); 300 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *, 301 unsigned int, unsigned int); 302 extern int bio_get_nr_vecs(struct block_device *); 303 extern struct bio *bio_map_user(struct request_queue *, struct block_device *, 304 unsigned long, unsigned int, int); 305 struct sg_iovec; 306 extern struct bio *bio_map_user_iov(struct request_queue *, 307 struct block_device *, 308 struct sg_iovec *, int, int); 309 extern void bio_unmap_user(struct bio *); 310 extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int, 311 gfp_t); 312 extern void bio_set_pages_dirty(struct bio *bio); 313 extern void bio_check_pages_dirty(struct bio *bio); 314 extern void bio_release_pages(struct bio *bio); 315 extern struct bio *bio_copy_user(struct request_queue *, unsigned long, unsigned int, int); 316 extern int bio_uncopy_user(struct bio *); 317 void zero_fill_bio(struct bio *bio); 318 319 #ifdef CONFIG_HIGHMEM 320 /* 321 * remember to add offset! and never ever reenable interrupts between a 322 * bvec_kmap_irq and bvec_kunmap_irq!! 323 * 324 * This function MUST be inlined - it plays with the CPU interrupt flags. 325 */ 326 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags) 327 { 328 unsigned long addr; 329 330 /* 331 * might not be a highmem page, but the preempt/irq count 332 * balancing is a lot nicer this way 333 */ 334 local_irq_save(*flags); 335 addr = (unsigned long) kmap_atomic(bvec->bv_page, KM_BIO_SRC_IRQ); 336 337 BUG_ON(addr & ~PAGE_MASK); 338 339 return (char *) addr + bvec->bv_offset; 340 } 341 342 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags) 343 { 344 unsigned long ptr = (unsigned long) buffer & PAGE_MASK; 345 346 kunmap_atomic((void *) ptr, KM_BIO_SRC_IRQ); 347 local_irq_restore(*flags); 348 } 349 350 #else 351 #define bvec_kmap_irq(bvec, flags) (page_address((bvec)->bv_page) + (bvec)->bv_offset) 352 #define bvec_kunmap_irq(buf, flags) do { *(flags) = 0; } while (0) 353 #endif 354 355 static inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx, 356 unsigned long *flags) 357 { 358 return bvec_kmap_irq(bio_iovec_idx(bio, idx), flags); 359 } 360 #define __bio_kunmap_irq(buf, flags) bvec_kunmap_irq(buf, flags) 361 362 #define bio_kmap_irq(bio, flags) \ 363 __bio_kmap_irq((bio), (bio)->bi_idx, (flags)) 364 #define bio_kunmap_irq(buf,flags) __bio_kunmap_irq(buf, flags) 365 366 #endif /* CONFIG_BLOCK */ 367 #endif /* __LINUX_BIO_H */ 368