1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * bvec iterator 4 * 5 * Copyright (C) 2001 Ming Lei <ming.lei@canonical.com> 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 /** 66 * bvec_set_virt - initialize a bvec based on a virtual address 67 * @bv: bvec to initialize 68 * @vaddr: virtual address to set the bvec to 69 * @len: length of the bvec 70 */ 71 static inline void bvec_set_virt(struct bio_vec *bv, void *vaddr, 72 unsigned int len) 73 { 74 bvec_set_page(bv, virt_to_page(vaddr), len, offset_in_page(vaddr)); 75 } 76 77 struct bvec_iter { 78 sector_t bi_sector; /* device address in 512 byte 79 sectors */ 80 unsigned int bi_size; /* residual I/O count */ 81 82 unsigned int bi_idx; /* current index into bvl_vec */ 83 84 unsigned int bi_bvec_done; /* number of bytes completed in 85 current bvec */ 86 } __packed; 87 88 struct bvec_iter_all { 89 struct bio_vec bv; 90 int idx; 91 unsigned done; 92 }; 93 94 /* 95 * various member access, note that bio_data should of course not be used 96 * on highmem page vectors 97 */ 98 #define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx]) 99 100 /* multi-page (mp_bvec) helpers */ 101 #define mp_bvec_iter_page(bvec, iter) \ 102 (__bvec_iter_bvec((bvec), (iter))->bv_page) 103 104 #define mp_bvec_iter_len(bvec, iter) \ 105 min((iter).bi_size, \ 106 __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done) 107 108 #define mp_bvec_iter_offset(bvec, iter) \ 109 (__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done) 110 111 #define mp_bvec_iter_page_idx(bvec, iter) \ 112 (mp_bvec_iter_offset((bvec), (iter)) / PAGE_SIZE) 113 114 #define mp_bvec_iter_bvec(bvec, iter) \ 115 ((struct bio_vec) { \ 116 .bv_page = mp_bvec_iter_page((bvec), (iter)), \ 117 .bv_len = mp_bvec_iter_len((bvec), (iter)), \ 118 .bv_offset = mp_bvec_iter_offset((bvec), (iter)), \ 119 }) 120 121 /* For building single-page bvec in flight */ 122 #define bvec_iter_offset(bvec, iter) \ 123 (mp_bvec_iter_offset((bvec), (iter)) % PAGE_SIZE) 124 125 #define bvec_iter_len(bvec, iter) \ 126 min_t(unsigned, mp_bvec_iter_len((bvec), (iter)), \ 127 PAGE_SIZE - bvec_iter_offset((bvec), (iter))) 128 129 #define bvec_iter_page(bvec, iter) \ 130 (mp_bvec_iter_page((bvec), (iter)) + \ 131 mp_bvec_iter_page_idx((bvec), (iter))) 132 133 #define bvec_iter_bvec(bvec, iter) \ 134 ((struct bio_vec) { \ 135 .bv_page = bvec_iter_page((bvec), (iter)), \ 136 .bv_len = bvec_iter_len((bvec), (iter)), \ 137 .bv_offset = bvec_iter_offset((bvec), (iter)), \ 138 }) 139 140 static inline bool bvec_iter_advance(const struct bio_vec *bv, 141 struct bvec_iter *iter, unsigned bytes) 142 { 143 unsigned int idx = iter->bi_idx; 144 145 if (WARN_ONCE(bytes > iter->bi_size, 146 "Attempted to advance past end of bvec iter\n")) { 147 iter->bi_size = 0; 148 return false; 149 } 150 151 iter->bi_size -= bytes; 152 bytes += iter->bi_bvec_done; 153 154 while (bytes && bytes >= bv[idx].bv_len) { 155 bytes -= bv[idx].bv_len; 156 idx++; 157 } 158 159 iter->bi_idx = idx; 160 iter->bi_bvec_done = bytes; 161 return true; 162 } 163 164 /* 165 * A simpler version of bvec_iter_advance(), @bytes should not span 166 * across multiple bvec entries, i.e. bytes <= bv[i->bi_idx].bv_len 167 */ 168 static inline void bvec_iter_advance_single(const struct bio_vec *bv, 169 struct bvec_iter *iter, unsigned int bytes) 170 { 171 unsigned int done = iter->bi_bvec_done + bytes; 172 173 if (done == bv[iter->bi_idx].bv_len) { 174 done = 0; 175 iter->bi_idx++; 176 } 177 iter->bi_bvec_done = done; 178 iter->bi_size -= bytes; 179 } 180 181 #define for_each_bvec(bvl, bio_vec, iter, start) \ 182 for (iter = (start); \ 183 (iter).bi_size && \ 184 ((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \ 185 bvec_iter_advance_single((bio_vec), &(iter), (bvl).bv_len)) 186 187 /* for iterating one bio from start to end */ 188 #define BVEC_ITER_ALL_INIT (struct bvec_iter) \ 189 { \ 190 .bi_sector = 0, \ 191 .bi_size = UINT_MAX, \ 192 .bi_idx = 0, \ 193 .bi_bvec_done = 0, \ 194 } 195 196 static inline struct bio_vec *bvec_init_iter_all(struct bvec_iter_all *iter_all) 197 { 198 iter_all->done = 0; 199 iter_all->idx = 0; 200 201 return &iter_all->bv; 202 } 203 204 static inline void bvec_advance(const struct bio_vec *bvec, 205 struct bvec_iter_all *iter_all) 206 { 207 struct bio_vec *bv = &iter_all->bv; 208 209 if (iter_all->done) { 210 bv->bv_page++; 211 bv->bv_offset = 0; 212 } else { 213 bv->bv_page = bvec->bv_page + (bvec->bv_offset >> PAGE_SHIFT); 214 bv->bv_offset = bvec->bv_offset & ~PAGE_MASK; 215 } 216 bv->bv_len = min_t(unsigned int, PAGE_SIZE - bv->bv_offset, 217 bvec->bv_len - iter_all->done); 218 iter_all->done += bv->bv_len; 219 220 if (iter_all->done == bvec->bv_len) { 221 iter_all->idx++; 222 iter_all->done = 0; 223 } 224 } 225 226 /** 227 * bvec_kmap_local - map a bvec into the kernel virtual address space 228 * @bvec: bvec to map 229 * 230 * Must be called on single-page bvecs only. Call kunmap_local on the returned 231 * address to unmap. 232 */ 233 static inline void *bvec_kmap_local(struct bio_vec *bvec) 234 { 235 return kmap_local_page(bvec->bv_page) + bvec->bv_offset; 236 } 237 238 /** 239 * memcpy_from_bvec - copy data from a bvec 240 * @bvec: bvec to copy from 241 * 242 * Must be called on single-page bvecs only. 243 */ 244 static inline void memcpy_from_bvec(char *to, struct bio_vec *bvec) 245 { 246 memcpy_from_page(to, bvec->bv_page, bvec->bv_offset, bvec->bv_len); 247 } 248 249 /** 250 * memcpy_to_bvec - copy data to a bvec 251 * @bvec: bvec to copy to 252 * 253 * Must be called on single-page bvecs only. 254 */ 255 static inline void memcpy_to_bvec(struct bio_vec *bvec, const char *from) 256 { 257 memcpy_to_page(bvec->bv_page, bvec->bv_offset, from, bvec->bv_len); 258 } 259 260 /** 261 * memzero_bvec - zero all data in a bvec 262 * @bvec: bvec to zero 263 * 264 * Must be called on single-page bvecs only. 265 */ 266 static inline void memzero_bvec(struct bio_vec *bvec) 267 { 268 memzero_page(bvec->bv_page, bvec->bv_offset, bvec->bv_len); 269 } 270 271 /** 272 * bvec_virt - return the virtual address for a bvec 273 * @bvec: bvec to return the virtual address for 274 * 275 * Note: the caller must ensure that @bvec->bv_page is not a highmem page. 276 */ 277 static inline void *bvec_virt(struct bio_vec *bvec) 278 { 279 WARN_ON_ONCE(PageHighMem(bvec->bv_page)); 280 return page_address(bvec->bv_page) + bvec->bv_offset; 281 } 282 283 #endif /* __LINUX_BVEC_H */ 284