Commit | Line | Data |
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4f18cd31 AV |
1 | #include <linux/export.h> |
2 | #include <linux/uio.h> | |
3 | #include <linux/pagemap.h> | |
91f79c43 AV |
4 | #include <linux/slab.h> |
5 | #include <linux/vmalloc.h> | |
4f18cd31 | 6 | |
62a8067a | 7 | static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes, |
4f18cd31 AV |
8 | struct iov_iter *i) |
9 | { | |
10 | size_t skip, copy, left, wanted; | |
11 | const struct iovec *iov; | |
12 | char __user *buf; | |
13 | void *kaddr, *from; | |
14 | ||
15 | if (unlikely(bytes > i->count)) | |
16 | bytes = i->count; | |
17 | ||
18 | if (unlikely(!bytes)) | |
19 | return 0; | |
20 | ||
21 | wanted = bytes; | |
22 | iov = i->iov; | |
23 | skip = i->iov_offset; | |
24 | buf = iov->iov_base + skip; | |
25 | copy = min(bytes, iov->iov_len - skip); | |
26 | ||
27 | if (!fault_in_pages_writeable(buf, copy)) { | |
28 | kaddr = kmap_atomic(page); | |
29 | from = kaddr + offset; | |
30 | ||
31 | /* first chunk, usually the only one */ | |
32 | left = __copy_to_user_inatomic(buf, from, copy); | |
33 | copy -= left; | |
34 | skip += copy; | |
35 | from += copy; | |
36 | bytes -= copy; | |
37 | ||
38 | while (unlikely(!left && bytes)) { | |
39 | iov++; | |
40 | buf = iov->iov_base; | |
41 | copy = min(bytes, iov->iov_len); | |
42 | left = __copy_to_user_inatomic(buf, from, copy); | |
43 | copy -= left; | |
44 | skip = copy; | |
45 | from += copy; | |
46 | bytes -= copy; | |
47 | } | |
48 | if (likely(!bytes)) { | |
49 | kunmap_atomic(kaddr); | |
50 | goto done; | |
51 | } | |
52 | offset = from - kaddr; | |
53 | buf += copy; | |
54 | kunmap_atomic(kaddr); | |
55 | copy = min(bytes, iov->iov_len - skip); | |
56 | } | |
57 | /* Too bad - revert to non-atomic kmap */ | |
58 | kaddr = kmap(page); | |
59 | from = kaddr + offset; | |
60 | left = __copy_to_user(buf, from, copy); | |
61 | copy -= left; | |
62 | skip += copy; | |
63 | from += copy; | |
64 | bytes -= copy; | |
65 | while (unlikely(!left && bytes)) { | |
66 | iov++; | |
67 | buf = iov->iov_base; | |
68 | copy = min(bytes, iov->iov_len); | |
69 | left = __copy_to_user(buf, from, copy); | |
70 | copy -= left; | |
71 | skip = copy; | |
72 | from += copy; | |
73 | bytes -= copy; | |
74 | } | |
75 | kunmap(page); | |
76 | done: | |
81055e58 AV |
77 | if (skip == iov->iov_len) { |
78 | iov++; | |
79 | skip = 0; | |
80 | } | |
4f18cd31 AV |
81 | i->count -= wanted - bytes; |
82 | i->nr_segs -= iov - i->iov; | |
83 | i->iov = iov; | |
84 | i->iov_offset = skip; | |
85 | return wanted - bytes; | |
86 | } | |
4f18cd31 | 87 | |
62a8067a | 88 | static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t bytes, |
f0d1bec9 AV |
89 | struct iov_iter *i) |
90 | { | |
91 | size_t skip, copy, left, wanted; | |
92 | const struct iovec *iov; | |
93 | char __user *buf; | |
94 | void *kaddr, *to; | |
95 | ||
96 | if (unlikely(bytes > i->count)) | |
97 | bytes = i->count; | |
98 | ||
99 | if (unlikely(!bytes)) | |
100 | return 0; | |
101 | ||
102 | wanted = bytes; | |
103 | iov = i->iov; | |
104 | skip = i->iov_offset; | |
105 | buf = iov->iov_base + skip; | |
106 | copy = min(bytes, iov->iov_len - skip); | |
107 | ||
108 | if (!fault_in_pages_readable(buf, copy)) { | |
109 | kaddr = kmap_atomic(page); | |
110 | to = kaddr + offset; | |
111 | ||
112 | /* first chunk, usually the only one */ | |
113 | left = __copy_from_user_inatomic(to, buf, copy); | |
114 | copy -= left; | |
115 | skip += copy; | |
116 | to += copy; | |
117 | bytes -= copy; | |
118 | ||
119 | while (unlikely(!left && bytes)) { | |
120 | iov++; | |
121 | buf = iov->iov_base; | |
122 | copy = min(bytes, iov->iov_len); | |
123 | left = __copy_from_user_inatomic(to, buf, copy); | |
124 | copy -= left; | |
125 | skip = copy; | |
126 | to += copy; | |
127 | bytes -= copy; | |
128 | } | |
129 | if (likely(!bytes)) { | |
130 | kunmap_atomic(kaddr); | |
131 | goto done; | |
132 | } | |
133 | offset = to - kaddr; | |
134 | buf += copy; | |
135 | kunmap_atomic(kaddr); | |
136 | copy = min(bytes, iov->iov_len - skip); | |
137 | } | |
138 | /* Too bad - revert to non-atomic kmap */ | |
139 | kaddr = kmap(page); | |
140 | to = kaddr + offset; | |
141 | left = __copy_from_user(to, buf, copy); | |
142 | copy -= left; | |
143 | skip += copy; | |
144 | to += copy; | |
145 | bytes -= copy; | |
146 | while (unlikely(!left && bytes)) { | |
147 | iov++; | |
148 | buf = iov->iov_base; | |
149 | copy = min(bytes, iov->iov_len); | |
150 | left = __copy_from_user(to, buf, copy); | |
151 | copy -= left; | |
152 | skip = copy; | |
153 | to += copy; | |
154 | bytes -= copy; | |
155 | } | |
156 | kunmap(page); | |
157 | done: | |
81055e58 AV |
158 | if (skip == iov->iov_len) { |
159 | iov++; | |
160 | skip = 0; | |
161 | } | |
f0d1bec9 AV |
162 | i->count -= wanted - bytes; |
163 | i->nr_segs -= iov - i->iov; | |
164 | i->iov = iov; | |
165 | i->iov_offset = skip; | |
166 | return wanted - bytes; | |
167 | } | |
f0d1bec9 | 168 | |
4f18cd31 AV |
169 | static size_t __iovec_copy_from_user_inatomic(char *vaddr, |
170 | const struct iovec *iov, size_t base, size_t bytes) | |
171 | { | |
172 | size_t copied = 0, left = 0; | |
173 | ||
174 | while (bytes) { | |
175 | char __user *buf = iov->iov_base + base; | |
176 | int copy = min(bytes, iov->iov_len - base); | |
177 | ||
178 | base = 0; | |
179 | left = __copy_from_user_inatomic(vaddr, buf, copy); | |
180 | copied += copy; | |
181 | bytes -= copy; | |
182 | vaddr += copy; | |
183 | iov++; | |
184 | ||
185 | if (unlikely(left)) | |
186 | break; | |
187 | } | |
188 | return copied - left; | |
189 | } | |
190 | ||
191 | /* | |
192 | * Copy as much as we can into the page and return the number of bytes which | |
193 | * were successfully copied. If a fault is encountered then return the number of | |
194 | * bytes which were copied. | |
195 | */ | |
62a8067a | 196 | static size_t copy_from_user_atomic_iovec(struct page *page, |
4f18cd31 AV |
197 | struct iov_iter *i, unsigned long offset, size_t bytes) |
198 | { | |
199 | char *kaddr; | |
200 | size_t copied; | |
201 | ||
202 | kaddr = kmap_atomic(page); | |
203 | if (likely(i->nr_segs == 1)) { | |
204 | int left; | |
205 | char __user *buf = i->iov->iov_base + i->iov_offset; | |
206 | left = __copy_from_user_inatomic(kaddr + offset, buf, bytes); | |
207 | copied = bytes - left; | |
208 | } else { | |
209 | copied = __iovec_copy_from_user_inatomic(kaddr + offset, | |
210 | i->iov, i->iov_offset, bytes); | |
211 | } | |
212 | kunmap_atomic(kaddr); | |
213 | ||
214 | return copied; | |
215 | } | |
4f18cd31 | 216 | |
62a8067a | 217 | static void advance_iovec(struct iov_iter *i, size_t bytes) |
4f18cd31 AV |
218 | { |
219 | BUG_ON(i->count < bytes); | |
220 | ||
221 | if (likely(i->nr_segs == 1)) { | |
222 | i->iov_offset += bytes; | |
223 | i->count -= bytes; | |
224 | } else { | |
225 | const struct iovec *iov = i->iov; | |
226 | size_t base = i->iov_offset; | |
227 | unsigned long nr_segs = i->nr_segs; | |
228 | ||
229 | /* | |
230 | * The !iov->iov_len check ensures we skip over unlikely | |
231 | * zero-length segments (without overruning the iovec). | |
232 | */ | |
233 | while (bytes || unlikely(i->count && !iov->iov_len)) { | |
234 | int copy; | |
235 | ||
236 | copy = min(bytes, iov->iov_len - base); | |
237 | BUG_ON(!i->count || i->count < copy); | |
238 | i->count -= copy; | |
239 | bytes -= copy; | |
240 | base += copy; | |
241 | if (iov->iov_len == base) { | |
242 | iov++; | |
243 | nr_segs--; | |
244 | base = 0; | |
245 | } | |
246 | } | |
247 | i->iov = iov; | |
248 | i->iov_offset = base; | |
249 | i->nr_segs = nr_segs; | |
250 | } | |
251 | } | |
4f18cd31 AV |
252 | |
253 | /* | |
254 | * Fault in the first iovec of the given iov_iter, to a maximum length | |
255 | * of bytes. Returns 0 on success, or non-zero if the memory could not be | |
256 | * accessed (ie. because it is an invalid address). | |
257 | * | |
258 | * writev-intensive code may want this to prefault several iovecs -- that | |
259 | * would be possible (callers must not rely on the fact that _only_ the | |
260 | * first iovec will be faulted with the current implementation). | |
261 | */ | |
262 | int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) | |
263 | { | |
62a8067a AV |
264 | if (!(i->type & ITER_BVEC)) { |
265 | char __user *buf = i->iov->iov_base + i->iov_offset; | |
266 | bytes = min(bytes, i->iov->iov_len - i->iov_offset); | |
267 | return fault_in_pages_readable(buf, bytes); | |
268 | } | |
269 | return 0; | |
4f18cd31 AV |
270 | } |
271 | EXPORT_SYMBOL(iov_iter_fault_in_readable); | |
272 | ||
62a8067a | 273 | static unsigned long alignment_iovec(const struct iov_iter *i) |
886a3911 AV |
274 | { |
275 | const struct iovec *iov = i->iov; | |
276 | unsigned long res; | |
277 | size_t size = i->count; | |
278 | size_t n; | |
279 | ||
280 | if (!size) | |
281 | return 0; | |
282 | ||
283 | res = (unsigned long)iov->iov_base + i->iov_offset; | |
284 | n = iov->iov_len - i->iov_offset; | |
285 | if (n >= size) | |
286 | return res | size; | |
287 | size -= n; | |
288 | res |= n; | |
289 | while (size > (++iov)->iov_len) { | |
290 | res |= (unsigned long)iov->iov_base | iov->iov_len; | |
291 | size -= iov->iov_len; | |
292 | } | |
293 | res |= (unsigned long)iov->iov_base | size; | |
294 | return res; | |
295 | } | |
71d8e532 AV |
296 | |
297 | void iov_iter_init(struct iov_iter *i, int direction, | |
298 | const struct iovec *iov, unsigned long nr_segs, | |
299 | size_t count) | |
300 | { | |
301 | /* It will get better. Eventually... */ | |
302 | if (segment_eq(get_fs(), KERNEL_DS)) | |
62a8067a | 303 | direction |= ITER_KVEC; |
71d8e532 AV |
304 | i->type = direction; |
305 | i->iov = iov; | |
306 | i->nr_segs = nr_segs; | |
307 | i->iov_offset = 0; | |
308 | i->count = count; | |
309 | } | |
310 | EXPORT_SYMBOL(iov_iter_init); | |
7b2c99d1 | 311 | |
62a8067a | 312 | static ssize_t get_pages_iovec(struct iov_iter *i, |
2c80929c | 313 | struct page **pages, size_t maxsize, unsigned maxpages, |
7b2c99d1 AV |
314 | size_t *start) |
315 | { | |
316 | size_t offset = i->iov_offset; | |
317 | const struct iovec *iov = i->iov; | |
318 | size_t len; | |
319 | unsigned long addr; | |
320 | int n; | |
321 | int res; | |
322 | ||
323 | len = iov->iov_len - offset; | |
324 | if (len > i->count) | |
325 | len = i->count; | |
2c80929c MS |
326 | if (len > maxsize) |
327 | len = maxsize; | |
7b2c99d1 AV |
328 | addr = (unsigned long)iov->iov_base + offset; |
329 | len += *start = addr & (PAGE_SIZE - 1); | |
c7f3888a AV |
330 | if (len > maxpages * PAGE_SIZE) |
331 | len = maxpages * PAGE_SIZE; | |
7b2c99d1 AV |
332 | addr &= ~(PAGE_SIZE - 1); |
333 | n = (len + PAGE_SIZE - 1) / PAGE_SIZE; | |
334 | res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, pages); | |
335 | if (unlikely(res < 0)) | |
336 | return res; | |
337 | return (res == n ? len : res * PAGE_SIZE) - *start; | |
338 | } | |
f67da30c | 339 | |
62a8067a | 340 | static ssize_t get_pages_alloc_iovec(struct iov_iter *i, |
91f79c43 AV |
341 | struct page ***pages, size_t maxsize, |
342 | size_t *start) | |
343 | { | |
344 | size_t offset = i->iov_offset; | |
345 | const struct iovec *iov = i->iov; | |
346 | size_t len; | |
347 | unsigned long addr; | |
348 | void *p; | |
349 | int n; | |
350 | int res; | |
351 | ||
352 | len = iov->iov_len - offset; | |
353 | if (len > i->count) | |
354 | len = i->count; | |
355 | if (len > maxsize) | |
356 | len = maxsize; | |
357 | addr = (unsigned long)iov->iov_base + offset; | |
358 | len += *start = addr & (PAGE_SIZE - 1); | |
359 | addr &= ~(PAGE_SIZE - 1); | |
360 | n = (len + PAGE_SIZE - 1) / PAGE_SIZE; | |
361 | ||
362 | p = kmalloc(n * sizeof(struct page *), GFP_KERNEL); | |
363 | if (!p) | |
364 | p = vmalloc(n * sizeof(struct page *)); | |
365 | if (!p) | |
366 | return -ENOMEM; | |
367 | ||
368 | res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, p); | |
369 | if (unlikely(res < 0)) { | |
370 | kvfree(p); | |
371 | return res; | |
372 | } | |
373 | *pages = p; | |
374 | return (res == n ? len : res * PAGE_SIZE) - *start; | |
375 | } | |
91f79c43 | 376 | |
62a8067a | 377 | static int iov_iter_npages_iovec(const struct iov_iter *i, int maxpages) |
f67da30c AV |
378 | { |
379 | size_t offset = i->iov_offset; | |
380 | size_t size = i->count; | |
381 | const struct iovec *iov = i->iov; | |
382 | int npages = 0; | |
383 | int n; | |
384 | ||
385 | for (n = 0; size && n < i->nr_segs; n++, iov++) { | |
386 | unsigned long addr = (unsigned long)iov->iov_base + offset; | |
387 | size_t len = iov->iov_len - offset; | |
388 | offset = 0; | |
389 | if (unlikely(!len)) /* empty segment */ | |
390 | continue; | |
391 | if (len > size) | |
392 | len = size; | |
393 | npages += (addr + len + PAGE_SIZE - 1) / PAGE_SIZE | |
394 | - addr / PAGE_SIZE; | |
395 | if (npages >= maxpages) /* don't bother going further */ | |
396 | return maxpages; | |
397 | size -= len; | |
398 | offset = 0; | |
399 | } | |
400 | return min(npages, maxpages); | |
401 | } | |
62a8067a AV |
402 | |
403 | static void memcpy_from_page(char *to, struct page *page, size_t offset, size_t len) | |
404 | { | |
405 | char *from = kmap_atomic(page); | |
406 | memcpy(to, from + offset, len); | |
407 | kunmap_atomic(from); | |
408 | } | |
409 | ||
410 | static void memcpy_to_page(struct page *page, size_t offset, char *from, size_t len) | |
411 | { | |
412 | char *to = kmap_atomic(page); | |
413 | memcpy(to + offset, from, len); | |
414 | kunmap_atomic(to); | |
415 | } | |
416 | ||
417 | static size_t copy_page_to_iter_bvec(struct page *page, size_t offset, size_t bytes, | |
418 | struct iov_iter *i) | |
419 | { | |
420 | size_t skip, copy, wanted; | |
421 | const struct bio_vec *bvec; | |
422 | void *kaddr, *from; | |
423 | ||
424 | if (unlikely(bytes > i->count)) | |
425 | bytes = i->count; | |
426 | ||
427 | if (unlikely(!bytes)) | |
428 | return 0; | |
429 | ||
430 | wanted = bytes; | |
431 | bvec = i->bvec; | |
432 | skip = i->iov_offset; | |
433 | copy = min_t(size_t, bytes, bvec->bv_len - skip); | |
434 | ||
435 | kaddr = kmap_atomic(page); | |
436 | from = kaddr + offset; | |
437 | memcpy_to_page(bvec->bv_page, skip + bvec->bv_offset, from, copy); | |
438 | skip += copy; | |
439 | from += copy; | |
440 | bytes -= copy; | |
441 | while (bytes) { | |
442 | bvec++; | |
443 | copy = min(bytes, (size_t)bvec->bv_len); | |
444 | memcpy_to_page(bvec->bv_page, bvec->bv_offset, from, copy); | |
445 | skip = copy; | |
446 | from += copy; | |
447 | bytes -= copy; | |
448 | } | |
449 | kunmap_atomic(kaddr); | |
450 | if (skip == bvec->bv_len) { | |
451 | bvec++; | |
452 | skip = 0; | |
453 | } | |
454 | i->count -= wanted - bytes; | |
455 | i->nr_segs -= bvec - i->bvec; | |
456 | i->bvec = bvec; | |
457 | i->iov_offset = skip; | |
458 | return wanted - bytes; | |
459 | } | |
460 | ||
461 | static size_t copy_page_from_iter_bvec(struct page *page, size_t offset, size_t bytes, | |
462 | struct iov_iter *i) | |
463 | { | |
464 | size_t skip, copy, wanted; | |
465 | const struct bio_vec *bvec; | |
466 | void *kaddr, *to; | |
467 | ||
468 | if (unlikely(bytes > i->count)) | |
469 | bytes = i->count; | |
470 | ||
471 | if (unlikely(!bytes)) | |
472 | return 0; | |
473 | ||
474 | wanted = bytes; | |
475 | bvec = i->bvec; | |
476 | skip = i->iov_offset; | |
477 | ||
478 | kaddr = kmap_atomic(page); | |
479 | ||
480 | to = kaddr + offset; | |
481 | ||
482 | copy = min(bytes, bvec->bv_len - skip); | |
483 | ||
484 | memcpy_from_page(to, bvec->bv_page, bvec->bv_offset + skip, copy); | |
485 | ||
486 | to += copy; | |
487 | skip += copy; | |
488 | bytes -= copy; | |
489 | ||
490 | while (bytes) { | |
491 | bvec++; | |
492 | copy = min(bytes, (size_t)bvec->bv_len); | |
493 | memcpy_from_page(to, bvec->bv_page, bvec->bv_offset, copy); | |
494 | skip = copy; | |
495 | to += copy; | |
496 | bytes -= copy; | |
497 | } | |
498 | kunmap_atomic(kaddr); | |
499 | if (skip == bvec->bv_len) { | |
500 | bvec++; | |
501 | skip = 0; | |
502 | } | |
503 | i->count -= wanted; | |
504 | i->nr_segs -= bvec - i->bvec; | |
505 | i->bvec = bvec; | |
506 | i->iov_offset = skip; | |
507 | return wanted; | |
508 | } | |
509 | ||
510 | static size_t copy_from_user_bvec(struct page *page, | |
511 | struct iov_iter *i, unsigned long offset, size_t bytes) | |
512 | { | |
513 | char *kaddr; | |
514 | size_t left; | |
515 | const struct bio_vec *bvec; | |
516 | size_t base = i->iov_offset; | |
517 | ||
518 | kaddr = kmap_atomic(page); | |
519 | for (left = bytes, bvec = i->bvec; left; bvec++, base = 0) { | |
520 | size_t copy = min(left, bvec->bv_len - base); | |
521 | if (!bvec->bv_len) | |
522 | continue; | |
523 | memcpy_from_page(kaddr + offset, bvec->bv_page, | |
524 | bvec->bv_offset + base, copy); | |
525 | offset += copy; | |
526 | left -= copy; | |
527 | } | |
528 | kunmap_atomic(kaddr); | |
529 | return bytes; | |
530 | } | |
531 | ||
532 | static void advance_bvec(struct iov_iter *i, size_t bytes) | |
533 | { | |
534 | BUG_ON(i->count < bytes); | |
535 | ||
536 | if (likely(i->nr_segs == 1)) { | |
537 | i->iov_offset += bytes; | |
538 | i->count -= bytes; | |
539 | } else { | |
540 | const struct bio_vec *bvec = i->bvec; | |
541 | size_t base = i->iov_offset; | |
542 | unsigned long nr_segs = i->nr_segs; | |
543 | ||
544 | /* | |
545 | * The !iov->iov_len check ensures we skip over unlikely | |
546 | * zero-length segments (without overruning the iovec). | |
547 | */ | |
548 | while (bytes || unlikely(i->count && !bvec->bv_len)) { | |
549 | int copy; | |
550 | ||
551 | copy = min(bytes, bvec->bv_len - base); | |
552 | BUG_ON(!i->count || i->count < copy); | |
553 | i->count -= copy; | |
554 | bytes -= copy; | |
555 | base += copy; | |
556 | if (bvec->bv_len == base) { | |
557 | bvec++; | |
558 | nr_segs--; | |
559 | base = 0; | |
560 | } | |
561 | } | |
562 | i->bvec = bvec; | |
563 | i->iov_offset = base; | |
564 | i->nr_segs = nr_segs; | |
565 | } | |
566 | } | |
567 | ||
568 | static unsigned long alignment_bvec(const struct iov_iter *i) | |
569 | { | |
570 | const struct bio_vec *bvec = i->bvec; | |
571 | unsigned long res; | |
572 | size_t size = i->count; | |
573 | size_t n; | |
574 | ||
575 | if (!size) | |
576 | return 0; | |
577 | ||
578 | res = bvec->bv_offset + i->iov_offset; | |
579 | n = bvec->bv_len - i->iov_offset; | |
580 | if (n >= size) | |
581 | return res | size; | |
582 | size -= n; | |
583 | res |= n; | |
584 | while (size > (++bvec)->bv_len) { | |
585 | res |= bvec->bv_offset | bvec->bv_len; | |
586 | size -= bvec->bv_len; | |
587 | } | |
588 | res |= bvec->bv_offset | size; | |
589 | return res; | |
590 | } | |
591 | ||
592 | static ssize_t get_pages_bvec(struct iov_iter *i, | |
2c80929c | 593 | struct page **pages, size_t maxsize, unsigned maxpages, |
62a8067a AV |
594 | size_t *start) |
595 | { | |
596 | const struct bio_vec *bvec = i->bvec; | |
597 | size_t len = bvec->bv_len - i->iov_offset; | |
598 | if (len > i->count) | |
599 | len = i->count; | |
2c80929c MS |
600 | if (len > maxsize) |
601 | len = maxsize; | |
c7f3888a | 602 | /* can't be more than PAGE_SIZE */ |
62a8067a AV |
603 | *start = bvec->bv_offset + i->iov_offset; |
604 | ||
605 | get_page(*pages = bvec->bv_page); | |
606 | ||
607 | return len; | |
608 | } | |
609 | ||
610 | static ssize_t get_pages_alloc_bvec(struct iov_iter *i, | |
611 | struct page ***pages, size_t maxsize, | |
612 | size_t *start) | |
613 | { | |
614 | const struct bio_vec *bvec = i->bvec; | |
615 | size_t len = bvec->bv_len - i->iov_offset; | |
616 | if (len > i->count) | |
617 | len = i->count; | |
618 | if (len > maxsize) | |
619 | len = maxsize; | |
620 | *start = bvec->bv_offset + i->iov_offset; | |
621 | ||
622 | *pages = kmalloc(sizeof(struct page *), GFP_KERNEL); | |
623 | if (!*pages) | |
624 | return -ENOMEM; | |
625 | ||
626 | get_page(**pages = bvec->bv_page); | |
627 | ||
628 | return len; | |
629 | } | |
630 | ||
631 | static int iov_iter_npages_bvec(const struct iov_iter *i, int maxpages) | |
632 | { | |
633 | size_t offset = i->iov_offset; | |
634 | size_t size = i->count; | |
635 | const struct bio_vec *bvec = i->bvec; | |
636 | int npages = 0; | |
637 | int n; | |
638 | ||
639 | for (n = 0; size && n < i->nr_segs; n++, bvec++) { | |
640 | size_t len = bvec->bv_len - offset; | |
641 | offset = 0; | |
642 | if (unlikely(!len)) /* empty segment */ | |
643 | continue; | |
644 | if (len > size) | |
645 | len = size; | |
646 | npages++; | |
647 | if (npages >= maxpages) /* don't bother going further */ | |
648 | return maxpages; | |
649 | size -= len; | |
650 | offset = 0; | |
651 | } | |
652 | return min(npages, maxpages); | |
653 | } | |
654 | ||
655 | size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, | |
656 | struct iov_iter *i) | |
657 | { | |
658 | if (i->type & ITER_BVEC) | |
659 | return copy_page_to_iter_bvec(page, offset, bytes, i); | |
660 | else | |
661 | return copy_page_to_iter_iovec(page, offset, bytes, i); | |
662 | } | |
663 | EXPORT_SYMBOL(copy_page_to_iter); | |
664 | ||
665 | size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, | |
666 | struct iov_iter *i) | |
667 | { | |
668 | if (i->type & ITER_BVEC) | |
669 | return copy_page_from_iter_bvec(page, offset, bytes, i); | |
670 | else | |
671 | return copy_page_from_iter_iovec(page, offset, bytes, i); | |
672 | } | |
673 | EXPORT_SYMBOL(copy_page_from_iter); | |
674 | ||
675 | size_t iov_iter_copy_from_user_atomic(struct page *page, | |
676 | struct iov_iter *i, unsigned long offset, size_t bytes) | |
677 | { | |
678 | if (i->type & ITER_BVEC) | |
679 | return copy_from_user_bvec(page, i, offset, bytes); | |
680 | else | |
681 | return copy_from_user_atomic_iovec(page, i, offset, bytes); | |
682 | } | |
683 | EXPORT_SYMBOL(iov_iter_copy_from_user_atomic); | |
684 | ||
685 | void iov_iter_advance(struct iov_iter *i, size_t size) | |
686 | { | |
687 | if (i->type & ITER_BVEC) | |
688 | advance_bvec(i, size); | |
689 | else | |
690 | advance_iovec(i, size); | |
691 | } | |
692 | EXPORT_SYMBOL(iov_iter_advance); | |
693 | ||
694 | /* | |
695 | * Return the count of just the current iov_iter segment. | |
696 | */ | |
697 | size_t iov_iter_single_seg_count(const struct iov_iter *i) | |
698 | { | |
699 | if (i->nr_segs == 1) | |
700 | return i->count; | |
701 | else if (i->type & ITER_BVEC) | |
702 | return min(i->count, i->iov->iov_len - i->iov_offset); | |
703 | else | |
704 | return min(i->count, i->bvec->bv_len - i->iov_offset); | |
705 | } | |
706 | EXPORT_SYMBOL(iov_iter_single_seg_count); | |
707 | ||
708 | unsigned long iov_iter_alignment(const struct iov_iter *i) | |
709 | { | |
710 | if (i->type & ITER_BVEC) | |
711 | return alignment_bvec(i); | |
712 | else | |
713 | return alignment_iovec(i); | |
714 | } | |
715 | EXPORT_SYMBOL(iov_iter_alignment); | |
716 | ||
717 | ssize_t iov_iter_get_pages(struct iov_iter *i, | |
2c80929c | 718 | struct page **pages, size_t maxsize, unsigned maxpages, |
62a8067a AV |
719 | size_t *start) |
720 | { | |
721 | if (i->type & ITER_BVEC) | |
2c80929c | 722 | return get_pages_bvec(i, pages, maxsize, maxpages, start); |
62a8067a | 723 | else |
2c80929c | 724 | return get_pages_iovec(i, pages, maxsize, maxpages, start); |
62a8067a AV |
725 | } |
726 | EXPORT_SYMBOL(iov_iter_get_pages); | |
727 | ||
728 | ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, | |
729 | struct page ***pages, size_t maxsize, | |
730 | size_t *start) | |
731 | { | |
732 | if (i->type & ITER_BVEC) | |
733 | return get_pages_alloc_bvec(i, pages, maxsize, start); | |
734 | else | |
735 | return get_pages_alloc_iovec(i, pages, maxsize, start); | |
736 | } | |
737 | EXPORT_SYMBOL(iov_iter_get_pages_alloc); | |
738 | ||
739 | int iov_iter_npages(const struct iov_iter *i, int maxpages) | |
740 | { | |
741 | if (i->type & ITER_BVEC) | |
742 | return iov_iter_npages_bvec(i, maxpages); | |
743 | else | |
744 | return iov_iter_npages_iovec(i, maxpages); | |
745 | } | |
f67da30c | 746 | EXPORT_SYMBOL(iov_iter_npages); |