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 struct bvec_iter { 53 sector_t bi_sector; /* device address in 512 byte 54 sectors */ 55 unsigned int bi_size; /* residual I/O count */ 56 57 unsigned int bi_idx; /* current index into bvl_vec */ 58 59 unsigned int bi_bvec_done; /* number of bytes completed in 60 current bvec */ 61 } __packed; 62 63 struct bvec_iter_all { 64 struct bio_vec bv; 65 int idx; 66 unsigned done; 67 }; 68 69 /* 70 * various member access, note that bio_data should of course not be used 71 * on highmem page vectors 72 */ 73 #define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx]) 74 75 /* multi-page (mp_bvec) helpers */ 76 #define mp_bvec_iter_page(bvec, iter) \ 77 (__bvec_iter_bvec((bvec), (iter))->bv_page) 78 79 #define mp_bvec_iter_len(bvec, iter) \ 80 min((iter).bi_size, \ 81 __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done) 82 83 #define mp_bvec_iter_offset(bvec, iter) \ 84 (__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done) 85 86 #define mp_bvec_iter_page_idx(bvec, iter) \ 87 (mp_bvec_iter_offset((bvec), (iter)) / PAGE_SIZE) 88 89 #define mp_bvec_iter_bvec(bvec, iter) \ 90 ((struct bio_vec) { \ 91 .bv_page = mp_bvec_iter_page((bvec), (iter)), \ 92 .bv_len = mp_bvec_iter_len((bvec), (iter)), \ 93 .bv_offset = mp_bvec_iter_offset((bvec), (iter)), \ 94 }) 95 96 /* For building single-page bvec in flight */ 97 #define bvec_iter_offset(bvec, iter) \ 98 (mp_bvec_iter_offset((bvec), (iter)) % PAGE_SIZE) 99 100 #define bvec_iter_len(bvec, iter) \ 101 min_t(unsigned, mp_bvec_iter_len((bvec), (iter)), \ 102 PAGE_SIZE - bvec_iter_offset((bvec), (iter))) 103 104 #define bvec_iter_page(bvec, iter) \ 105 (mp_bvec_iter_page((bvec), (iter)) + \ 106 mp_bvec_iter_page_idx((bvec), (iter))) 107 108 #define bvec_iter_bvec(bvec, iter) \ 109 ((struct bio_vec) { \ 110 .bv_page = bvec_iter_page((bvec), (iter)), \ 111 .bv_len = bvec_iter_len((bvec), (iter)), \ 112 .bv_offset = bvec_iter_offset((bvec), (iter)), \ 113 }) 114 115 static inline bool bvec_iter_advance(const struct bio_vec *bv, 116 struct bvec_iter *iter, unsigned bytes) 117 { 118 unsigned int idx = iter->bi_idx; 119 120 if (WARN_ONCE(bytes > iter->bi_size, 121 "Attempted to advance past end of bvec iter\n")) { 122 iter->bi_size = 0; 123 return false; 124 } 125 126 iter->bi_size -= bytes; 127 bytes += iter->bi_bvec_done; 128 129 while (bytes && bytes >= bv[idx].bv_len) { 130 bytes -= bv[idx].bv_len; 131 idx++; 132 } 133 134 iter->bi_idx = idx; 135 iter->bi_bvec_done = bytes; 136 return true; 137 } 138 139 /* 140 * A simpler version of bvec_iter_advance(), @bytes should not span 141 * across multiple bvec entries, i.e. bytes <= bv[i->bi_idx].bv_len 142 */ 143 static inline void bvec_iter_advance_single(const struct bio_vec *bv, 144 struct bvec_iter *iter, unsigned int bytes) 145 { 146 unsigned int done = iter->bi_bvec_done + bytes; 147 148 if (done == bv[iter->bi_idx].bv_len) { 149 done = 0; 150 iter->bi_idx++; 151 } 152 iter->bi_bvec_done = done; 153 iter->bi_size -= bytes; 154 } 155 156 #define for_each_bvec(bvl, bio_vec, iter, start) \ 157 for (iter = (start); \ 158 (iter).bi_size && \ 159 ((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \ 160 bvec_iter_advance_single((bio_vec), &(iter), (bvl).bv_len)) 161 162 /* for iterating one bio from start to end */ 163 #define BVEC_ITER_ALL_INIT (struct bvec_iter) \ 164 { \ 165 .bi_sector = 0, \ 166 .bi_size = UINT_MAX, \ 167 .bi_idx = 0, \ 168 .bi_bvec_done = 0, \ 169 } 170 171 static inline struct bio_vec *bvec_init_iter_all(struct bvec_iter_all *iter_all) 172 { 173 iter_all->done = 0; 174 iter_all->idx = 0; 175 176 return &iter_all->bv; 177 } 178 179 static inline void bvec_advance(const struct bio_vec *bvec, 180 struct bvec_iter_all *iter_all) 181 { 182 struct bio_vec *bv = &iter_all->bv; 183 184 if (iter_all->done) { 185 bv->bv_page++; 186 bv->bv_offset = 0; 187 } else { 188 bv->bv_page = bvec->bv_page + (bvec->bv_offset >> PAGE_SHIFT); 189 bv->bv_offset = bvec->bv_offset & ~PAGE_MASK; 190 } 191 bv->bv_len = min_t(unsigned int, PAGE_SIZE - bv->bv_offset, 192 bvec->bv_len - iter_all->done); 193 iter_all->done += bv->bv_len; 194 195 if (iter_all->done == bvec->bv_len) { 196 iter_all->idx++; 197 iter_all->done = 0; 198 } 199 } 200 201 /** 202 * bvec_kmap_local - map a bvec into the kernel virtual address space 203 * @bvec: bvec to map 204 * 205 * Must be called on single-page bvecs only. Call kunmap_local on the returned 206 * address to unmap. 207 */ 208 static inline void *bvec_kmap_local(struct bio_vec *bvec) 209 { 210 return kmap_local_page(bvec->bv_page) + bvec->bv_offset; 211 } 212 213 /** 214 * memcpy_from_bvec - copy data from a bvec 215 * @bvec: bvec to copy from 216 * 217 * Must be called on single-page bvecs only. 218 */ 219 static inline void memcpy_from_bvec(char *to, struct bio_vec *bvec) 220 { 221 memcpy_from_page(to, bvec->bv_page, bvec->bv_offset, bvec->bv_len); 222 } 223 224 /** 225 * memcpy_to_bvec - copy data to a bvec 226 * @bvec: bvec to copy to 227 * 228 * Must be called on single-page bvecs only. 229 */ 230 static inline void memcpy_to_bvec(struct bio_vec *bvec, const char *from) 231 { 232 memcpy_to_page(bvec->bv_page, bvec->bv_offset, from, bvec->bv_len); 233 } 234 235 /** 236 * memzero_bvec - zero all data in a bvec 237 * @bvec: bvec to zero 238 * 239 * Must be called on single-page bvecs only. 240 */ 241 static inline void memzero_bvec(struct bio_vec *bvec) 242 { 243 memzero_page(bvec->bv_page, bvec->bv_offset, bvec->bv_len); 244 } 245 246 /** 247 * bvec_virt - return the virtual address for a bvec 248 * @bvec: bvec to return the virtual address for 249 * 250 * Note: the caller must ensure that @bvec->bv_page is not a highmem page. 251 */ 252 static inline void *bvec_virt(struct bio_vec *bvec) 253 { 254 WARN_ON_ONCE(PageHighMem(bvec->bv_page)); 255 return page_address(bvec->bv_page) + bvec->bv_offset; 256 } 257 258 #endif /* __LINUX_BVEC_H */ 259