projects/linux·blob v6.16 · refs

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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
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 * 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 */
31struct 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 */
44static 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/**
53 * bvec_set_folio - initialize a bvec based off a struct folio
54 * @bv: bvec to initialize
55 * @folio: folio the bvec should point to
56 * @len: length of the bvec
57 * @offset: offset into the folio
58 */
59static inline void bvec_set_folio(struct bio_vec *bv, struct folio *folio,
60 size_t len, size_t offset)
61{
62 unsigned long nr = offset / PAGE_SIZE;
63
64 WARN_ON_ONCE(len > UINT_MAX);
65 bvec_set_page(bv, folio_page(folio, nr), len, offset % PAGE_SIZE);
66}
67
68/**
69 * bvec_set_virt - initialize a bvec based on a virtual address
70 * @bv: bvec to initialize
71 * @vaddr: virtual address to set the bvec to
72 * @len: length of the bvec
73 */
74static inline void bvec_set_virt(struct bio_vec *bv, void *vaddr,
75 unsigned int len)
76{
77 bvec_set_page(bv, virt_to_page(vaddr), len, offset_in_page(vaddr));
78}
79
80struct bvec_iter {
81 sector_t bi_sector; /* device address in 512 byte
82 sectors */
83 unsigned int bi_size; /* residual I/O count */
84
85 unsigned int bi_idx; /* current index into bvl_vec */
86
87 unsigned int bi_bvec_done; /* number of bytes completed in
88 current bvec */
89} __packed __aligned(4);
90
91struct bvec_iter_all {
92 struct bio_vec bv;
93 int idx;
94 unsigned done;
95};
96
97/*
98 * various member access, note that bio_data should of course not be used
99 * on highmem page vectors
100 */
101#define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx])
102
103/* multi-page (mp_bvec) helpers */
104#define mp_bvec_iter_page(bvec, iter) \
105 (__bvec_iter_bvec((bvec), (iter))->bv_page)
106
107#define mp_bvec_iter_len(bvec, iter) \
108 min((iter).bi_size, \
109 __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
110
111#define mp_bvec_iter_offset(bvec, iter) \
112 (__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
113
114#define mp_bvec_iter_page_idx(bvec, iter) \
115 (mp_bvec_iter_offset((bvec), (iter)) / PAGE_SIZE)
116
117#define mp_bvec_iter_bvec(bvec, iter) \
118((struct bio_vec) { \
119 .bv_page = mp_bvec_iter_page((bvec), (iter)), \
120 .bv_len = mp_bvec_iter_len((bvec), (iter)), \
121 .bv_offset = mp_bvec_iter_offset((bvec), (iter)), \
122})
123
124/* For building single-page bvec in flight */
125 #define bvec_iter_offset(bvec, iter) \
126 (mp_bvec_iter_offset((bvec), (iter)) % PAGE_SIZE)
127
128#define bvec_iter_len(bvec, iter) \
129 min_t(unsigned, mp_bvec_iter_len((bvec), (iter)), \
130 PAGE_SIZE - bvec_iter_offset((bvec), (iter)))
131
132#define bvec_iter_page(bvec, iter) \
133 (mp_bvec_iter_page((bvec), (iter)) + \
134 mp_bvec_iter_page_idx((bvec), (iter)))
135
136#define bvec_iter_bvec(bvec, iter) \
137((struct bio_vec) { \
138 .bv_page = bvec_iter_page((bvec), (iter)), \
139 .bv_len = bvec_iter_len((bvec), (iter)), \
140 .bv_offset = bvec_iter_offset((bvec), (iter)), \
141})
142
143static inline bool bvec_iter_advance(const struct bio_vec *bv,
144 struct bvec_iter *iter, unsigned bytes)
145{
146 unsigned int idx = iter->bi_idx;
147
148 if (WARN_ONCE(bytes > iter->bi_size,
149 "Attempted to advance past end of bvec iter\n")) {
150 iter->bi_size = 0;
151 return false;
152 }
153
154 iter->bi_size -= bytes;
155 bytes += iter->bi_bvec_done;
156
157 while (bytes && bytes >= bv[idx].bv_len) {
158 bytes -= bv[idx].bv_len;
159 idx++;
160 }
161
162 iter->bi_idx = idx;
163 iter->bi_bvec_done = bytes;
164 return true;
165}
166
167/*
168 * A simpler version of bvec_iter_advance(), @bytes should not span
169 * across multiple bvec entries, i.e. bytes <= bv[i->bi_idx].bv_len
170 */
171static inline void bvec_iter_advance_single(const struct bio_vec *bv,
172 struct bvec_iter *iter, unsigned int bytes)
173{
174 unsigned int done = iter->bi_bvec_done + bytes;
175
176 if (done == bv[iter->bi_idx].bv_len) {
177 done = 0;
178 iter->bi_idx++;
179 }
180 iter->bi_bvec_done = done;
181 iter->bi_size -= bytes;
182}
183
184#define for_each_bvec(bvl, bio_vec, iter, start) \
185 for (iter = (start); \
186 (iter).bi_size && \
187 ((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \
188 bvec_iter_advance_single((bio_vec), &(iter), (bvl).bv_len))
189
190#define for_each_mp_bvec(bvl, bio_vec, iter, start) \
191 for (iter = (start); \
192 (iter).bi_size && \
193 ((bvl = mp_bvec_iter_bvec((bio_vec), (iter))), 1); \
194 bvec_iter_advance_single((bio_vec), &(iter), (bvl).bv_len))
195
196/* for iterating one bio from start to end */
197#define BVEC_ITER_ALL_INIT (struct bvec_iter) \
198{ \
199 .bi_sector = 0, \
200 .bi_size = UINT_MAX, \
201 .bi_idx = 0, \
202 .bi_bvec_done = 0, \
203}
204
205static inline struct bio_vec *bvec_init_iter_all(struct bvec_iter_all *iter_all)
206{
207 iter_all->done = 0;
208 iter_all->idx = 0;
209
210 return &iter_all->bv;
211}
212
213static inline void bvec_advance(const struct bio_vec *bvec,
214 struct bvec_iter_all *iter_all)
215{
216 struct bio_vec *bv = &iter_all->bv;
217
218 if (iter_all->done) {
219 bv->bv_page++;
220 bv->bv_offset = 0;
221 } else {
222 bv->bv_page = bvec->bv_page + (bvec->bv_offset >> PAGE_SHIFT);
223 bv->bv_offset = bvec->bv_offset & ~PAGE_MASK;
224 }
225 bv->bv_len = min_t(unsigned int, PAGE_SIZE - bv->bv_offset,
226 bvec->bv_len - iter_all->done);
227 iter_all->done += bv->bv_len;
228
229 if (iter_all->done == bvec->bv_len) {
230 iter_all->idx++;
231 iter_all->done = 0;
232 }
233}
234
235/**
236 * bvec_kmap_local - map a bvec into the kernel virtual address space
237 * @bvec: bvec to map
238 *
239 * Must be called on single-page bvecs only. Call kunmap_local on the returned
240 * address to unmap.
241 */
242static inline void *bvec_kmap_local(struct bio_vec *bvec)
243{
244 return kmap_local_page(bvec->bv_page) + bvec->bv_offset;
245}
246
247/**
248 * memcpy_from_bvec - copy data from a bvec
249 * @bvec: bvec to copy from
250 *
251 * Must be called on single-page bvecs only.
252 */
253static inline void memcpy_from_bvec(char *to, struct bio_vec *bvec)
254{
255 memcpy_from_page(to, bvec->bv_page, bvec->bv_offset, bvec->bv_len);
256}
257
258/**
259 * memcpy_to_bvec - copy data to a bvec
260 * @bvec: bvec to copy to
261 *
262 * Must be called on single-page bvecs only.
263 */
264static inline void memcpy_to_bvec(struct bio_vec *bvec, const char *from)
265{
266 memcpy_to_page(bvec->bv_page, bvec->bv_offset, from, bvec->bv_len);
267}
268
269/**
270 * memzero_bvec - zero all data in a bvec
271 * @bvec: bvec to zero
272 *
273 * Must be called on single-page bvecs only.
274 */
275static inline void memzero_bvec(struct bio_vec *bvec)
276{
277 memzero_page(bvec->bv_page, bvec->bv_offset, bvec->bv_len);
278}
279
280/**
281 * bvec_virt - return the virtual address for a bvec
282 * @bvec: bvec to return the virtual address for
283 *
284 * Note: the caller must ensure that @bvec->bv_page is not a highmem page.
285 */
286static inline void *bvec_virt(struct bio_vec *bvec)
287{
288 WARN_ON_ONCE(PageHighMem(bvec->bv_page));
289 return page_address(bvec->bv_page) + bvec->bv_offset;
290}
291
292/**
293 * bvec_phys - return the physical address for a bvec
294 * @bvec: bvec to return the physical address for
295 */
296static inline phys_addr_t bvec_phys(const struct bio_vec *bvec)
297{
298 return page_to_phys(bvec->bv_page) + bvec->bv_offset;
299}
300
301#endif /* __LINUX_BVEC_H */