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_ITER_H 8 #define __LINUX_BVEC_ITER_H 9 10 #include <linux/kernel.h> 11 #include <linux/bug.h> 12 #include <linux/errno.h> 13 #include <linux/mm.h> 14 15 /* 16 * was unsigned short, but we might as well be ready for > 64kB I/O pages 17 */ 18 struct bio_vec { 19 struct page *bv_page; 20 unsigned int bv_len; 21 unsigned int bv_offset; 22 }; 23 24 struct bvec_iter { 25 sector_t bi_sector; /* device address in 512 byte 26 sectors */ 27 unsigned int bi_size; /* residual I/O count */ 28 29 unsigned int bi_idx; /* current index into bvl_vec */ 30 31 unsigned int bi_bvec_done; /* number of bytes completed in 32 current bvec */ 33 }; 34 35 struct bvec_iter_all { 36 struct bio_vec bv; 37 int idx; 38 unsigned done; 39 }; 40 41 /* 42 * various member access, note that bio_data should of course not be used 43 * on highmem page vectors 44 */ 45 #define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx]) 46 47 /* multi-page (mp_bvec) helpers */ 48 #define mp_bvec_iter_page(bvec, iter) \ 49 (__bvec_iter_bvec((bvec), (iter))->bv_page) 50 51 #define mp_bvec_iter_len(bvec, iter) \ 52 min((iter).bi_size, \ 53 __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done) 54 55 #define mp_bvec_iter_offset(bvec, iter) \ 56 (__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done) 57 58 #define mp_bvec_iter_page_idx(bvec, iter) \ 59 (mp_bvec_iter_offset((bvec), (iter)) / PAGE_SIZE) 60 61 #define mp_bvec_iter_bvec(bvec, iter) \ 62 ((struct bio_vec) { \ 63 .bv_page = mp_bvec_iter_page((bvec), (iter)), \ 64 .bv_len = mp_bvec_iter_len((bvec), (iter)), \ 65 .bv_offset = mp_bvec_iter_offset((bvec), (iter)), \ 66 }) 67 68 /* For building single-page bvec in flight */ 69 #define bvec_iter_offset(bvec, iter) \ 70 (mp_bvec_iter_offset((bvec), (iter)) % PAGE_SIZE) 71 72 #define bvec_iter_len(bvec, iter) \ 73 min_t(unsigned, mp_bvec_iter_len((bvec), (iter)), \ 74 PAGE_SIZE - bvec_iter_offset((bvec), (iter))) 75 76 #define bvec_iter_page(bvec, iter) \ 77 (mp_bvec_iter_page((bvec), (iter)) + \ 78 mp_bvec_iter_page_idx((bvec), (iter))) 79 80 #define bvec_iter_bvec(bvec, iter) \ 81 ((struct bio_vec) { \ 82 .bv_page = bvec_iter_page((bvec), (iter)), \ 83 .bv_len = bvec_iter_len((bvec), (iter)), \ 84 .bv_offset = bvec_iter_offset((bvec), (iter)), \ 85 }) 86 87 static inline bool bvec_iter_advance(const struct bio_vec *bv, 88 struct bvec_iter *iter, unsigned bytes) 89 { 90 unsigned int idx = iter->bi_idx; 91 92 if (WARN_ONCE(bytes > iter->bi_size, 93 "Attempted to advance past end of bvec iter\n")) { 94 iter->bi_size = 0; 95 return false; 96 } 97 98 iter->bi_size -= bytes; 99 bytes += iter->bi_bvec_done; 100 101 while (bytes && bytes >= bv[idx].bv_len) { 102 bytes -= bv[idx].bv_len; 103 idx++; 104 } 105 106 iter->bi_idx = idx; 107 iter->bi_bvec_done = bytes; 108 return true; 109 } 110 111 #define for_each_bvec(bvl, bio_vec, iter, start) \ 112 for (iter = (start); \ 113 (iter).bi_size && \ 114 ((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \ 115 bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len)) 116 117 /* for iterating one bio from start to end */ 118 #define BVEC_ITER_ALL_INIT (struct bvec_iter) \ 119 { \ 120 .bi_sector = 0, \ 121 .bi_size = UINT_MAX, \ 122 .bi_idx = 0, \ 123 .bi_bvec_done = 0, \ 124 } 125 126 static inline struct bio_vec *bvec_init_iter_all(struct bvec_iter_all *iter_all) 127 { 128 iter_all->done = 0; 129 iter_all->idx = 0; 130 131 return &iter_all->bv; 132 } 133 134 static inline void bvec_advance(const struct bio_vec *bvec, 135 struct bvec_iter_all *iter_all) 136 { 137 struct bio_vec *bv = &iter_all->bv; 138 139 if (iter_all->done) { 140 bv->bv_page++; 141 bv->bv_offset = 0; 142 } else { 143 bv->bv_page = bvec->bv_page + (bvec->bv_offset >> PAGE_SHIFT); 144 bv->bv_offset = bvec->bv_offset & ~PAGE_MASK; 145 } 146 bv->bv_len = min_t(unsigned int, PAGE_SIZE - bv->bv_offset, 147 bvec->bv_len - iter_all->done); 148 iter_all->done += bv->bv_len; 149 150 if (iter_all->done == bvec->bv_len) { 151 iter_all->idx++; 152 iter_all->done = 0; 153 } 154 } 155 156 #endif /* __LINUX_BVEC_ITER_H */ 157