1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * bvec iterator 4 * 5 * Copyright (C) 2001 Ming Lei <[email protected]> 6 */ 7 #ifndef __LINUX_BVEC_H 8 #define __LINUX_BVEC_H 9 10 #include <linux/highmem.h> 11 #include <linux/bug.h> 12 #include <linux/errno.h> 13 #include <linux/limits.h> 14 #include <linux/minmax.h> 15 #include <linux/types.h> 16 17 struct page; 18 19 /** 20 * struct bio_vec - a contiguous range of physical memory addresses 21 * @bv_page: First page associated with the address range. 22 * @bv_len: Number of bytes in the address range. 23 * @bv_offset: Start of the address range relative to the start of @bv_page. 24 * 25 * The following holds for a bvec if n * PAGE_SIZE < bv_offset + bv_len: 26 * 27 * nth_page(@bv_page, n) == @bv_page + n 28 * 29 * This holds because page_is_mergeable() checks the above property. 30 */ 31 struct bio_vec { 32 struct page *bv_page; 33 unsigned int bv_len; 34 unsigned int bv_offset; 35 }; 36 37 /** 38 * bvec_set_page - initialize a bvec based off a struct page 39 * @bv: bvec to initialize 40 * @page: page the bvec should point to 41 * @len: length of the bvec 42 * @offset: offset into the page 43 */ 44 static inline void bvec_set_page(struct bio_vec *bv, struct page *page, 45 unsigned int len, unsigned int offset) 46 { 47 bv->bv_page = page; 48 bv->bv_len = len; 49 bv->bv_offset = offset; 50 } 51 52 /** 53 * bvec_set_folio - initialize a bvec based off a struct folio 54 * @bv: bvec to initialize 55 * @folio: folio the bvec should point to 56 * @len: length of the bvec 57 * @offset: offset into the folio 58 */ 59 static inline void bvec_set_folio(struct bio_vec *bv, struct folio *folio, 60 unsigned int len, unsigned int offset) 61 { 62 bvec_set_page(bv, &folio->page, len, offset); 63 } 64 65 struct bvec_iter { 66 sector_t bi_sector; /* device address in 512 byte 67 sectors */ 68 unsigned int bi_size; /* residual I/O count */ 69 70 unsigned int bi_idx; /* current index into bvl_vec */ 71 72 unsigned int bi_bvec_done; /* number of bytes completed in 73 current bvec */ 74 } __packed; 75 76 struct bvec_iter_all { 77 struct bio_vec bv; 78 int idx; 79 unsigned done; 80 }; 81 82 /* 83 * various member access, note that bio_data should of course not be used 84 * on highmem page vectors 85 */ 86 #define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx]) 87 88 /* multi-page (mp_bvec) helpers */ 89 #define mp_bvec_iter_page(bvec, iter) \ 90 (__bvec_iter_bvec((bvec), (iter))->bv_page) 91 92 #define mp_bvec_iter_len(bvec, iter) \ 93 min((iter).bi_size, \ 94 __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done) 95 96 #define mp_bvec_iter_offset(bvec, iter) \ 97 (__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done) 98 99 #define mp_bvec_iter_page_idx(bvec, iter) \ 100 (mp_bvec_iter_offset((bvec), (iter)) / PAGE_SIZE) 101 102 #define mp_bvec_iter_bvec(bvec, iter) \ 103 ((struct bio_vec) { \ 104 .bv_page = mp_bvec_iter_page((bvec), (iter)), \ 105 .bv_len = mp_bvec_iter_len((bvec), (iter)), \ 106 .bv_offset = mp_bvec_iter_offset((bvec), (iter)), \ 107 }) 108 109 /* For building single-page bvec in flight */ 110 #define bvec_iter_offset(bvec, iter) \ 111 (mp_bvec_iter_offset((bvec), (iter)) % PAGE_SIZE) 112 113 #define bvec_iter_len(bvec, iter) \ 114 min_t(unsigned, mp_bvec_iter_len((bvec), (iter)), \ 115 PAGE_SIZE - bvec_iter_offset((bvec), (iter))) 116 117 #define bvec_iter_page(bvec, iter) \ 118 (mp_bvec_iter_page((bvec), (iter)) + \ 119 mp_bvec_iter_page_idx((bvec), (iter))) 120 121 #define bvec_iter_bvec(bvec, iter) \ 122 ((struct bio_vec) { \ 123 .bv_page = bvec_iter_page((bvec), (iter)), \ 124 .bv_len = bvec_iter_len((bvec), (iter)), \ 125 .bv_offset = bvec_iter_offset((bvec), (iter)), \ 126 }) 127 128 static inline bool bvec_iter_advance(const struct bio_vec *bv, 129 struct bvec_iter *iter, unsigned bytes) 130 { 131 unsigned int idx = iter->bi_idx; 132 133 if (WARN_ONCE(bytes > iter->bi_size, 134 "Attempted to advance past end of bvec iter\n")) { 135 iter->bi_size = 0; 136 return false; 137 } 138 139 iter->bi_size -= bytes; 140 bytes += iter->bi_bvec_done; 141 142 while (bytes && bytes >= bv[idx].bv_len) { 143 bytes -= bv[idx].bv_len; 144 idx++; 145 } 146 147 iter->bi_idx = idx; 148 iter->bi_bvec_done = bytes; 149 return true; 150 } 151 152 /* 153 * A simpler version of bvec_iter_advance(), @bytes should not span 154 * across multiple bvec entries, i.e. bytes <= bv[i->bi_idx].bv_len 155 */ 156 static inline void bvec_iter_advance_single(const struct bio_vec *bv, 157 struct bvec_iter *iter, unsigned int bytes) 158 { 159 unsigned int done = iter->bi_bvec_done + bytes; 160 161 if (done == bv[iter->bi_idx].bv_len) { 162 done = 0; 163 iter->bi_idx++; 164 } 165 iter->bi_bvec_done = done; 166 iter->bi_size -= bytes; 167 } 168 169 #define for_each_bvec(bvl, bio_vec, iter, start) \ 170 for (iter = (start); \ 171 (iter).bi_size && \ 172 ((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \ 173 bvec_iter_advance_single((bio_vec), &(iter), (bvl).bv_len)) 174 175 /* for iterating one bio from start to end */ 176 #define BVEC_ITER_ALL_INIT (struct bvec_iter) \ 177 { \ 178 .bi_sector = 0, \ 179 .bi_size = UINT_MAX, \ 180 .bi_idx = 0, \ 181 .bi_bvec_done = 0, \ 182 } 183 184 static inline struct bio_vec *bvec_init_iter_all(struct bvec_iter_all *iter_all) 185 { 186 iter_all->done = 0; 187 iter_all->idx = 0; 188 189 return &iter_all->bv; 190 } 191 192 static inline void bvec_advance(const struct bio_vec *bvec, 193 struct bvec_iter_all *iter_all) 194 { 195 struct bio_vec *bv = &iter_all->bv; 196 197 if (iter_all->done) { 198 bv->bv_page++; 199 bv->bv_offset = 0; 200 } else { 201 bv->bv_page = bvec->bv_page + (bvec->bv_offset >> PAGE_SHIFT); 202 bv->bv_offset = bvec->bv_offset & ~PAGE_MASK; 203 } 204 bv->bv_len = min_t(unsigned int, PAGE_SIZE - bv->bv_offset, 205 bvec->bv_len - iter_all->done); 206 iter_all->done += bv->bv_len; 207 208 if (iter_all->done == bvec->bv_len) { 209 iter_all->idx++; 210 iter_all->done = 0; 211 } 212 } 213 214 /** 215 * bvec_kmap_local - map a bvec into the kernel virtual address space 216 * @bvec: bvec to map 217 * 218 * Must be called on single-page bvecs only. Call kunmap_local on the returned 219 * address to unmap. 220 */ 221 static inline void *bvec_kmap_local(struct bio_vec *bvec) 222 { 223 return kmap_local_page(bvec->bv_page) + bvec->bv_offset; 224 } 225 226 /** 227 * memcpy_from_bvec - copy data from a bvec 228 * @bvec: bvec to copy from 229 * 230 * Must be called on single-page bvecs only. 231 */ 232 static inline void memcpy_from_bvec(char *to, struct bio_vec *bvec) 233 { 234 memcpy_from_page(to, bvec->bv_page, bvec->bv_offset, bvec->bv_len); 235 } 236 237 /** 238 * memcpy_to_bvec - copy data to a bvec 239 * @bvec: bvec to copy to 240 * 241 * Must be called on single-page bvecs only. 242 */ 243 static inline void memcpy_to_bvec(struct bio_vec *bvec, const char *from) 244 { 245 memcpy_to_page(bvec->bv_page, bvec->bv_offset, from, bvec->bv_len); 246 } 247 248 /** 249 * memzero_bvec - zero all data in a bvec 250 * @bvec: bvec to zero 251 * 252 * Must be called on single-page bvecs only. 253 */ 254 static inline void memzero_bvec(struct bio_vec *bvec) 255 { 256 memzero_page(bvec->bv_page, bvec->bv_offset, bvec->bv_len); 257 } 258 259 /** 260 * bvec_virt - return the virtual address for a bvec 261 * @bvec: bvec to return the virtual address for 262 * 263 * Note: the caller must ensure that @bvec->bv_page is not a highmem page. 264 */ 265 static inline void *bvec_virt(struct bio_vec *bvec) 266 { 267 WARN_ON_ONCE(PageHighMem(bvec->bv_page)); 268 return page_address(bvec->bv_page) + bvec->bv_offset; 269 } 270 271 #endif /* __LINUX_BVEC_H */ 272