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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
17struct 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 * All pages within a bio_vec starting from @bv_page are contiguous and
26 * can simply be iterated (see bvec_advance()).
27 */
28struct bio_vec {
29 struct page *bv_page;
30 unsigned int bv_len;
31 unsigned int bv_offset;
32};
33
34/**
35 * bvec_set_page - initialize a bvec based off a struct page
36 * @bv: bvec to initialize
37 * @page: page the bvec should point to
38 * @len: length of the bvec
39 * @offset: offset into the page
40 */
41static inline void bvec_set_page(struct bio_vec *bv, struct page *page,
42 unsigned int len, unsigned int offset)
43{
44 bv->bv_page = page;
45 bv->bv_len = len;
46 bv->bv_offset = offset;
47}
48
49/**
50 * bvec_set_folio - initialize a bvec based off a struct folio
51 * @bv: bvec to initialize
52 * @folio: folio the bvec should point to
53 * @len: length of the bvec
54 * @offset: offset into the folio
55 */
56static inline void bvec_set_folio(struct bio_vec *bv, struct folio *folio,
57 size_t len, size_t offset)
58{
59 unsigned long nr = offset / PAGE_SIZE;
60
61 WARN_ON_ONCE(len > UINT_MAX);
62 bvec_set_page(bv, folio_page(folio, nr), len, offset: offset % PAGE_SIZE);
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 */
71static 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
77struct 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 __aligned(4);
87
88struct 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
140static 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 */
168static 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#define for_each_mp_bvec(bvl, bio_vec, iter, start) \
188 for (iter = (start); \
189 (iter).bi_size && \
190 ((bvl = mp_bvec_iter_bvec((bio_vec), (iter))), 1); \
191 bvec_iter_advance_single((bio_vec), &(iter), (bvl).bv_len))
192
193/* for iterating one bio from start to end */
194#define BVEC_ITER_ALL_INIT (struct bvec_iter) \
195{ \
196 .bi_sector = 0, \
197 .bi_size = UINT_MAX, \
198 .bi_idx = 0, \
199 .bi_bvec_done = 0, \
200}
201
202static inline struct bio_vec *bvec_init_iter_all(struct bvec_iter_all *iter_all)
203{
204 iter_all->done = 0;
205 iter_all->idx = 0;
206
207 return &iter_all->bv;
208}
209
210static inline void bvec_advance(const struct bio_vec *bvec,
211 struct bvec_iter_all *iter_all)
212{
213 struct bio_vec *bv = &iter_all->bv;
214
215 if (iter_all->done) {
216 bv->bv_page++;
217 bv->bv_offset = 0;
218 } else {
219 bv->bv_page = bvec->bv_page + (bvec->bv_offset >> PAGE_SHIFT);
220 bv->bv_offset = bvec->bv_offset & ~PAGE_MASK;
221 }
222 bv->bv_len = min_t(unsigned int, PAGE_SIZE - bv->bv_offset,
223 bvec->bv_len - iter_all->done);
224 iter_all->done += bv->bv_len;
225
226 if (iter_all->done == bvec->bv_len) {
227 iter_all->idx++;
228 iter_all->done = 0;
229 }
230}
231
232/**
233 * bvec_kmap_local - map a bvec into the kernel virtual address space
234 * @bvec: bvec to map
235 *
236 * Must be called on single-page bvecs only. Call kunmap_local on the returned
237 * address to unmap.
238 */
239static inline void *bvec_kmap_local(struct bio_vec *bvec)
240{
241 return kmap_local_page(page: bvec->bv_page) + bvec->bv_offset;
242}
243
244/**
245 * memcpy_from_bvec - copy data from a bvec
246 * @bvec: bvec to copy from
247 *
248 * Must be called on single-page bvecs only.
249 */
250static inline void memcpy_from_bvec(char *to, struct bio_vec *bvec)
251{
252 memcpy_from_page(to, page: bvec->bv_page, offset: bvec->bv_offset, len: bvec->bv_len);
253}
254
255/**
256 * memcpy_to_bvec - copy data to a bvec
257 * @bvec: bvec to copy to
258 *
259 * Must be called on single-page bvecs only.
260 */
261static inline void memcpy_to_bvec(struct bio_vec *bvec, const char *from)
262{
263 memcpy_to_page(page: bvec->bv_page, offset: bvec->bv_offset, from, len: bvec->bv_len);
264}
265
266/**
267 * memzero_bvec - zero all data in a bvec
268 * @bvec: bvec to zero
269 *
270 * Must be called on single-page bvecs only.
271 */
272static inline void memzero_bvec(struct bio_vec *bvec)
273{
274 memzero_page(page: bvec->bv_page, offset: bvec->bv_offset, len: bvec->bv_len);
275}
276
277/**
278 * bvec_virt - return the virtual address for a bvec
279 * @bvec: bvec to return the virtual address for
280 *
281 * Note: the caller must ensure that @bvec->bv_page is not a highmem page.
282 */
283static inline void *bvec_virt(struct bio_vec *bvec)
284{
285 WARN_ON_ONCE(PageHighMem(bvec->bv_page));
286 return page_address(bvec->bv_page) + bvec->bv_offset;
287}
288
289/**
290 * bvec_phys - return the physical address for a bvec
291 * @bvec: bvec to return the physical address for
292 */
293static inline phys_addr_t bvec_phys(const struct bio_vec *bvec)
294{
295 return page_to_phys(bvec->bv_page) + bvec->bv_offset;
296}
297
298#endif /* __LINUX_BVEC_H */
299

source code of linux/include/linux/bvec.h