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