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 | |