Line data Source code
1 : /*
2 : * Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com>
3 : *
4 : * Scatterlist handling helpers.
5 : *
6 : * This source code is licensed under the GNU General Public License,
7 : * Version 2. See the file COPYING for more details.
8 : */
9 : #include <linux/export.h>
10 : #include <linux/slab.h>
11 : #include <linux/scatterlist.h>
12 : #include <linux/highmem.h>
13 : #include <linux/kmemleak.h>
14 :
15 : /**
16 : * sg_next - return the next scatterlist entry in a list
17 : * @sg: The current sg entry
18 : *
19 : * Description:
20 : * Usually the next entry will be @sg@ + 1, but if this sg element is part
21 : * of a chained scatterlist, it could jump to the start of a new
22 : * scatterlist array.
23 : *
24 : **/
25 138310 : struct scatterlist *sg_next(struct scatterlist *sg)
26 : {
27 : #ifdef CONFIG_DEBUG_SG
28 : BUG_ON(sg->sg_magic != SG_MAGIC);
29 : #endif
30 138310 : if (sg_is_last(sg))
31 : return NULL;
32 :
33 119010 : sg++;
34 119010 : if (unlikely(sg_is_chain(sg)))
35 0 : sg = sg_chain_ptr(sg);
36 :
37 119010 : return sg;
38 : }
39 : EXPORT_SYMBOL(sg_next);
40 :
41 : /**
42 : * sg_nents - return total count of entries in scatterlist
43 : * @sg: The scatterlist
44 : *
45 : * Description:
46 : * Allows to know how many entries are in sg, taking into acount
47 : * chaining as well
48 : *
49 : **/
50 0 : int sg_nents(struct scatterlist *sg)
51 : {
52 : int nents;
53 0 : for (nents = 0; sg; sg = sg_next(sg))
54 0 : nents++;
55 0 : return nents;
56 : }
57 : EXPORT_SYMBOL(sg_nents);
58 :
59 :
60 : /**
61 : * sg_last - return the last scatterlist entry in a list
62 : * @sgl: First entry in the scatterlist
63 : * @nents: Number of entries in the scatterlist
64 : *
65 : * Description:
66 : * Should only be used casually, it (currently) scans the entire list
67 : * to get the last entry.
68 : *
69 : * Note that the @sgl@ pointer passed in need not be the first one,
70 : * the important bit is that @nents@ denotes the number of entries that
71 : * exist from @sgl@.
72 : *
73 : **/
74 0 : struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents)
75 : {
76 : #ifndef CONFIG_ARCH_HAS_SG_CHAIN
77 0 : struct scatterlist *ret = &sgl[nents - 1];
78 : #else
79 : struct scatterlist *sg, *ret = NULL;
80 : unsigned int i;
81 :
82 : for_each_sg(sgl, sg, nents, i)
83 : ret = sg;
84 :
85 : #endif
86 : #ifdef CONFIG_DEBUG_SG
87 : BUG_ON(sgl[0].sg_magic != SG_MAGIC);
88 : BUG_ON(!sg_is_last(ret));
89 : #endif
90 0 : return ret;
91 : }
92 : EXPORT_SYMBOL(sg_last);
93 :
94 : /**
95 : * sg_init_table - Initialize SG table
96 : * @sgl: The SG table
97 : * @nents: Number of entries in table
98 : *
99 : * Notes:
100 : * If this is part of a chained sg table, sg_mark_end() should be
101 : * used only on the last table part.
102 : *
103 : **/
104 6 : void sg_init_table(struct scatterlist *sgl, unsigned int nents)
105 : {
106 6 : memset(sgl, 0, sizeof(*sgl) * nents);
107 : #ifdef CONFIG_DEBUG_SG
108 : {
109 : unsigned int i;
110 : for (i = 0; i < nents; i++)
111 : sgl[i].sg_magic = SG_MAGIC;
112 : }
113 : #endif
114 6 : sg_mark_end(&sgl[nents - 1]);
115 6 : }
116 : EXPORT_SYMBOL(sg_init_table);
117 :
118 : /**
119 : * sg_init_one - Initialize a single entry sg list
120 : * @sg: SG entry
121 : * @buf: Virtual address for IO
122 : * @buflen: IO length
123 : *
124 : **/
125 4 : void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen)
126 : {
127 4 : sg_init_table(sg, 1);
128 : sg_set_buf(sg, buf, buflen);
129 4 : }
130 : EXPORT_SYMBOL(sg_init_one);
131 :
132 : /*
133 : * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree
134 : * helpers.
135 : */
136 0 : static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
137 : {
138 0 : if (nents == SG_MAX_SINGLE_ALLOC) {
139 : /*
140 : * Kmemleak doesn't track page allocations as they are not
141 : * commonly used (in a raw form) for kernel data structures.
142 : * As we chain together a list of pages and then a normal
143 : * kmalloc (tracked by kmemleak), in order to for that last
144 : * allocation not to become decoupled (and thus a
145 : * false-positive) we need to inform kmemleak of all the
146 : * intermediate allocations.
147 : */
148 0 : void *ptr = (void *) __get_free_page(gfp_mask);
149 : kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask);
150 0 : return ptr;
151 : } else
152 0 : return kmalloc(nents * sizeof(struct scatterlist), gfp_mask);
153 : }
154 :
155 0 : static void sg_kfree(struct scatterlist *sg, unsigned int nents)
156 : {
157 0 : if (nents == SG_MAX_SINGLE_ALLOC) {
158 : kmemleak_free(sg);
159 0 : free_page((unsigned long) sg);
160 : } else
161 0 : kfree(sg);
162 0 : }
163 :
164 : /**
165 : * __sg_free_table - Free a previously mapped sg table
166 : * @table: The sg table header to use
167 : * @max_ents: The maximum number of entries per single scatterlist
168 : * @skip_first_chunk: don't free the (preallocated) first scatterlist chunk
169 : * @free_fn: Free function
170 : *
171 : * Description:
172 : * Free an sg table previously allocated and setup with
173 : * __sg_alloc_table(). The @max_ents value must be identical to
174 : * that previously used with __sg_alloc_table().
175 : *
176 : **/
177 0 : void __sg_free_table(struct sg_table *table, unsigned int max_ents,
178 : bool skip_first_chunk, sg_free_fn *free_fn)
179 : {
180 : struct scatterlist *sgl, *next;
181 :
182 0 : if (unlikely(!table->sgl))
183 0 : return;
184 :
185 : sgl = table->sgl;
186 0 : while (table->orig_nents) {
187 : unsigned int alloc_size = table->orig_nents;
188 : unsigned int sg_size;
189 :
190 : /*
191 : * If we have more than max_ents segments left,
192 : * then assign 'next' to the sg table after the current one.
193 : * sg_size is then one less than alloc size, since the last
194 : * element is the chain pointer.
195 : */
196 0 : if (alloc_size > max_ents) {
197 0 : next = sg_chain_ptr(&sgl[max_ents - 1]);
198 : alloc_size = max_ents;
199 0 : sg_size = alloc_size - 1;
200 : } else {
201 : sg_size = alloc_size;
202 : next = NULL;
203 : }
204 :
205 0 : table->orig_nents -= sg_size;
206 0 : if (skip_first_chunk)
207 : skip_first_chunk = false;
208 : else
209 0 : free_fn(sgl, alloc_size);
210 : sgl = next;
211 : }
212 :
213 0 : table->sgl = NULL;
214 : }
215 : EXPORT_SYMBOL(__sg_free_table);
216 :
217 : /**
218 : * sg_free_table - Free a previously allocated sg table
219 : * @table: The mapped sg table header
220 : *
221 : **/
222 0 : void sg_free_table(struct sg_table *table)
223 : {
224 0 : __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);
225 0 : }
226 : EXPORT_SYMBOL(sg_free_table);
227 :
228 : /**
229 : * __sg_alloc_table - Allocate and initialize an sg table with given allocator
230 : * @table: The sg table header to use
231 : * @nents: Number of entries in sg list
232 : * @max_ents: The maximum number of entries the allocator returns per call
233 : * @gfp_mask: GFP allocation mask
234 : * @alloc_fn: Allocator to use
235 : *
236 : * Description:
237 : * This function returns a @table @nents long. The allocator is
238 : * defined to return scatterlist chunks of maximum size @max_ents.
239 : * Thus if @nents is bigger than @max_ents, the scatterlists will be
240 : * chained in units of @max_ents.
241 : *
242 : * Notes:
243 : * If this function returns non-0 (eg failure), the caller must call
244 : * __sg_free_table() to cleanup any leftover allocations.
245 : *
246 : **/
247 0 : int __sg_alloc_table(struct sg_table *table, unsigned int nents,
248 : unsigned int max_ents, struct scatterlist *first_chunk,
249 : gfp_t gfp_mask, sg_alloc_fn *alloc_fn)
250 : {
251 : struct scatterlist *sg, *prv;
252 : unsigned int left;
253 :
254 0 : memset(table, 0, sizeof(*table));
255 :
256 0 : if (nents == 0)
257 : return -EINVAL;
258 : #ifndef CONFIG_ARCH_HAS_SG_CHAIN
259 0 : if (WARN_ON_ONCE(nents > max_ents))
260 : return -EINVAL;
261 : #endif
262 :
263 : left = nents;
264 : prv = NULL;
265 : do {
266 : unsigned int sg_size, alloc_size = left;
267 :
268 0 : if (alloc_size > max_ents) {
269 : alloc_size = max_ents;
270 0 : sg_size = alloc_size - 1;
271 : } else
272 : sg_size = alloc_size;
273 :
274 0 : left -= sg_size;
275 :
276 0 : if (first_chunk) {
277 : sg = first_chunk;
278 : first_chunk = NULL;
279 : } else {
280 0 : sg = alloc_fn(alloc_size, gfp_mask);
281 : }
282 0 : if (unlikely(!sg)) {
283 : /*
284 : * Adjust entry count to reflect that the last
285 : * entry of the previous table won't be used for
286 : * linkage. Without this, sg_kfree() may get
287 : * confused.
288 : */
289 0 : if (prv)
290 0 : table->nents = ++table->orig_nents;
291 :
292 : return -ENOMEM;
293 : }
294 :
295 0 : sg_init_table(sg, alloc_size);
296 0 : table->nents = table->orig_nents += sg_size;
297 :
298 : /*
299 : * If this is the first mapping, assign the sg table header.
300 : * If this is not the first mapping, chain previous part.
301 : */
302 0 : if (prv)
303 : sg_chain(prv, max_ents, sg);
304 : else
305 0 : table->sgl = sg;
306 :
307 : /*
308 : * If no more entries after this one, mark the end
309 : */
310 0 : if (!left)
311 0 : sg_mark_end(&sg[sg_size - 1]);
312 :
313 : prv = sg;
314 0 : } while (left);
315 :
316 : return 0;
317 : }
318 : EXPORT_SYMBOL(__sg_alloc_table);
319 :
320 : /**
321 : * sg_alloc_table - Allocate and initialize an sg table
322 : * @table: The sg table header to use
323 : * @nents: Number of entries in sg list
324 : * @gfp_mask: GFP allocation mask
325 : *
326 : * Description:
327 : * Allocate and initialize an sg table. If @nents@ is larger than
328 : * SG_MAX_SINGLE_ALLOC a chained sg table will be setup.
329 : *
330 : **/
331 0 : int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
332 : {
333 : int ret;
334 :
335 0 : ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
336 : NULL, gfp_mask, sg_kmalloc);
337 0 : if (unlikely(ret))
338 0 : __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);
339 :
340 0 : return ret;
341 : }
342 : EXPORT_SYMBOL(sg_alloc_table);
343 :
344 : /**
345 : * sg_alloc_table_from_pages - Allocate and initialize an sg table from
346 : * an array of pages
347 : * @sgt: The sg table header to use
348 : * @pages: Pointer to an array of page pointers
349 : * @n_pages: Number of pages in the pages array
350 : * @offset: Offset from start of the first page to the start of a buffer
351 : * @size: Number of valid bytes in the buffer (after offset)
352 : * @gfp_mask: GFP allocation mask
353 : *
354 : * Description:
355 : * Allocate and initialize an sg table from a list of pages. Contiguous
356 : * ranges of the pages are squashed into a single scatterlist node. A user
357 : * may provide an offset at a start and a size of valid data in a buffer
358 : * specified by the page array. The returned sg table is released by
359 : * sg_free_table.
360 : *
361 : * Returns:
362 : * 0 on success, negative error on failure
363 : */
364 0 : int sg_alloc_table_from_pages(struct sg_table *sgt,
365 : struct page **pages, unsigned int n_pages,
366 : unsigned long offset, unsigned long size,
367 : gfp_t gfp_mask)
368 : {
369 : unsigned int chunks;
370 : unsigned int i;
371 : unsigned int cur_page;
372 : int ret;
373 : struct scatterlist *s;
374 :
375 : /* compute number of contiguous chunks */
376 : chunks = 1;
377 0 : for (i = 1; i < n_pages; ++i)
378 0 : if (page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1)
379 0 : ++chunks;
380 :
381 0 : ret = sg_alloc_table(sgt, chunks, gfp_mask);
382 0 : if (unlikely(ret))
383 : return ret;
384 :
385 : /* merging chunks and putting them into the scatterlist */
386 : cur_page = 0;
387 0 : for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
388 : unsigned long chunk_size;
389 : unsigned int j;
390 :
391 : /* look for the end of the current chunk */
392 0 : for (j = cur_page + 1; j < n_pages; ++j)
393 0 : if (page_to_pfn(pages[j]) !=
394 0 : page_to_pfn(pages[j - 1]) + 1)
395 : break;
396 :
397 0 : chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset;
398 0 : sg_set_page(s, pages[cur_page], min(size, chunk_size), offset);
399 0 : size -= chunk_size;
400 : offset = 0;
401 : cur_page = j;
402 : }
403 :
404 : return 0;
405 : }
406 : EXPORT_SYMBOL(sg_alloc_table_from_pages);
407 :
408 0 : void __sg_page_iter_start(struct sg_page_iter *piter,
409 : struct scatterlist *sglist, unsigned int nents,
410 : unsigned long pgoffset)
411 : {
412 3899 : piter->__pg_advance = 0;
413 3899 : piter->__nents = nents;
414 :
415 3899 : piter->sg = sglist;
416 3899 : piter->sg_pgoffset = pgoffset;
417 0 : }
418 : EXPORT_SYMBOL(__sg_page_iter_start);
419 :
420 : static int sg_page_count(struct scatterlist *sg)
421 : {
422 39 : return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT;
423 : }
424 :
425 39 : bool __sg_page_iter_next(struct sg_page_iter *piter)
426 : {
427 78 : if (!piter->__nents || !piter->sg)
428 : return false;
429 :
430 39 : piter->sg_pgoffset += piter->__pg_advance;
431 39 : piter->__pg_advance = 1;
432 :
433 117 : while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {
434 0 : piter->sg_pgoffset -= sg_page_count(piter->sg);
435 0 : piter->sg = sg_next(piter->sg);
436 0 : if (!--piter->__nents || !piter->sg)
437 : return false;
438 : }
439 :
440 : return true;
441 : }
442 : EXPORT_SYMBOL(__sg_page_iter_next);
443 :
444 : /**
445 : * sg_miter_start - start mapping iteration over a sg list
446 : * @miter: sg mapping iter to be started
447 : * @sgl: sg list to iterate over
448 : * @nents: number of sg entries
449 : *
450 : * Description:
451 : * Starts mapping iterator @miter.
452 : *
453 : * Context:
454 : * Don't care.
455 : */
456 3899 : void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
457 : unsigned int nents, unsigned int flags)
458 : {
459 3899 : memset(miter, 0, sizeof(struct sg_mapping_iter));
460 :
461 : __sg_page_iter_start(&miter->piter, sgl, nents, 0);
462 : WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG)));
463 3899 : miter->__flags = flags;
464 3899 : }
465 : EXPORT_SYMBOL(sg_miter_start);
466 :
467 40 : static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)
468 : {
469 40 : if (!miter->__remaining) {
470 : struct scatterlist *sg;
471 : unsigned long pgoffset;
472 :
473 39 : if (!__sg_page_iter_next(&miter->piter))
474 : return false;
475 :
476 39 : sg = miter->piter.sg;
477 39 : pgoffset = miter->piter.sg_pgoffset;
478 :
479 39 : miter->__offset = pgoffset ? 0 : sg->offset;
480 117 : miter->__remaining = sg->offset + sg->length -
481 78 : (pgoffset << PAGE_SHIFT) - miter->__offset;
482 39 : miter->__remaining = min_t(unsigned long, miter->__remaining,
483 : PAGE_SIZE - miter->__offset);
484 : }
485 :
486 : return true;
487 : }
488 :
489 : /**
490 : * sg_miter_skip - reposition mapping iterator
491 : * @miter: sg mapping iter to be skipped
492 : * @offset: number of bytes to plus the current location
493 : *
494 : * Description:
495 : * Sets the offset of @miter to its current location plus @offset bytes.
496 : * If mapping iterator @miter has been proceeded by sg_miter_next(), this
497 : * stops @miter.
498 : *
499 : * Context:
500 : * Don't care if @miter is stopped, or not proceeded yet.
501 : * Otherwise, preemption disabled if the SG_MITER_ATOMIC is set.
502 : *
503 : * Returns:
504 : * true if @miter contains the valid mapping. false if end of sg
505 : * list is reached.
506 : */
507 0 : bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset)
508 : {
509 0 : sg_miter_stop(miter);
510 :
511 0 : while (offset) {
512 : off_t consumed;
513 :
514 0 : if (!sg_miter_get_next_page(miter))
515 : return false;
516 :
517 0 : consumed = min_t(off_t, offset, miter->__remaining);
518 0 : miter->__offset += consumed;
519 0 : miter->__remaining -= consumed;
520 0 : offset -= consumed;
521 : }
522 :
523 : return true;
524 : }
525 : EXPORT_SYMBOL(sg_miter_skip);
526 :
527 : /**
528 : * sg_miter_next - proceed mapping iterator to the next mapping
529 : * @miter: sg mapping iter to proceed
530 : *
531 : * Description:
532 : * Proceeds @miter to the next mapping. @miter should have been started
533 : * using sg_miter_start(). On successful return, @miter->page,
534 : * @miter->addr and @miter->length point to the current mapping.
535 : *
536 : * Context:
537 : * Preemption disabled if SG_MITER_ATOMIC. Preemption must stay disabled
538 : * till @miter is stopped. May sleep if !SG_MITER_ATOMIC.
539 : *
540 : * Returns:
541 : * true if @miter contains the next mapping. false if end of sg
542 : * list is reached.
543 : */
544 40 : bool sg_miter_next(struct sg_mapping_iter *miter)
545 : {
546 40 : sg_miter_stop(miter);
547 :
548 : /*
549 : * Get to the next page if necessary.
550 : * __remaining, __offset is adjusted by sg_miter_stop
551 : */
552 40 : if (!sg_miter_get_next_page(miter))
553 : return false;
554 :
555 80 : miter->page = sg_page_iter_page(&miter->piter);
556 40 : miter->consumed = miter->length = miter->__remaining;
557 :
558 40 : if (miter->__flags & SG_MITER_ATOMIC)
559 40 : miter->addr = kmap_atomic(miter->page) + miter->__offset;
560 : else
561 0 : miter->addr = kmap(miter->page) + miter->__offset;
562 :
563 : return true;
564 : }
565 : EXPORT_SYMBOL(sg_miter_next);
566 :
567 : /**
568 : * sg_miter_stop - stop mapping iteration
569 : * @miter: sg mapping iter to be stopped
570 : *
571 : * Description:
572 : * Stops mapping iterator @miter. @miter should have been started
573 : * started using sg_miter_start(). A stopped iteration can be
574 : * resumed by calling sg_miter_next() on it. This is useful when
575 : * resources (kmap) need to be released during iteration.
576 : *
577 : * Context:
578 : * Preemption disabled if the SG_MITER_ATOMIC is set. Don't care
579 : * otherwise.
580 : */
581 80 : void sg_miter_stop(struct sg_mapping_iter *miter)
582 : {
583 : WARN_ON(miter->consumed > miter->length);
584 :
585 : /* drop resources from the last iteration */
586 80 : if (miter->addr) {
587 40 : miter->__offset += miter->consumed;
588 40 : miter->__remaining -= miter->consumed;
589 :
590 79 : if ((miter->__flags & SG_MITER_TO_SG) &&
591 39 : !PageSlab(miter->page))
592 35 : flush_kernel_dcache_page(miter->page);
593 :
594 40 : if (miter->__flags & SG_MITER_ATOMIC) {
595 40 : WARN_ON_ONCE(preemptible());
596 : kunmap_atomic(miter->addr);
597 : } else
598 : kunmap(miter->page);
599 :
600 40 : miter->page = NULL;
601 40 : miter->addr = NULL;
602 40 : miter->length = 0;
603 40 : miter->consumed = 0;
604 : }
605 80 : }
606 : EXPORT_SYMBOL(sg_miter_stop);
607 :
608 : /**
609 : * sg_copy_buffer - Copy data between a linear buffer and an SG list
610 : * @sgl: The SG list
611 : * @nents: Number of SG entries
612 : * @buf: Where to copy from
613 : * @buflen: The number of bytes to copy
614 : * @skip: Number of bytes to skip before copying
615 : * @to_buffer: transfer direction (true == from an sg list to a
616 : * buffer, false == from a buffer to an sg list
617 : *
618 : * Returns the number of copied bytes.
619 : *
620 : **/
621 0 : static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents,
622 : void *buf, size_t buflen, off_t skip,
623 : bool to_buffer)
624 : {
625 : unsigned int offset = 0;
626 : struct sg_mapping_iter miter;
627 : unsigned long flags;
628 : unsigned int sg_flags = SG_MITER_ATOMIC;
629 :
630 0 : if (to_buffer)
631 : sg_flags |= SG_MITER_FROM_SG;
632 : else
633 : sg_flags |= SG_MITER_TO_SG;
634 :
635 : sg_miter_start(&miter, sgl, nents, sg_flags);
636 :
637 0 : if (!sg_miter_skip(&miter, skip))
638 : return false;
639 :
640 : local_irq_save(flags);
641 :
642 0 : while (sg_miter_next(&miter) && offset < buflen) {
643 : unsigned int len;
644 :
645 0 : len = min(miter.length, buflen - offset);
646 :
647 0 : if (to_buffer)
648 0 : memcpy(buf + offset, miter.addr, len);
649 : else
650 0 : memcpy(miter.addr, buf + offset, len);
651 :
652 0 : offset += len;
653 : }
654 :
655 0 : sg_miter_stop(&miter);
656 :
657 0 : local_irq_restore(flags);
658 0 : return offset;
659 : }
660 :
661 : /**
662 : * sg_copy_from_buffer - Copy from a linear buffer to an SG list
663 : * @sgl: The SG list
664 : * @nents: Number of SG entries
665 : * @buf: Where to copy from
666 : * @buflen: The number of bytes to copy
667 : *
668 : * Returns the number of copied bytes.
669 : *
670 : **/
671 0 : size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
672 : void *buf, size_t buflen)
673 : {
674 0 : return sg_copy_buffer(sgl, nents, buf, buflen, 0, false);
675 : }
676 : EXPORT_SYMBOL(sg_copy_from_buffer);
677 :
678 : /**
679 : * sg_copy_to_buffer - Copy from an SG list to a linear buffer
680 : * @sgl: The SG list
681 : * @nents: Number of SG entries
682 : * @buf: Where to copy to
683 : * @buflen: The number of bytes to copy
684 : *
685 : * Returns the number of copied bytes.
686 : *
687 : **/
688 0 : size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
689 : void *buf, size_t buflen)
690 : {
691 0 : return sg_copy_buffer(sgl, nents, buf, buflen, 0, true);
692 : }
693 : EXPORT_SYMBOL(sg_copy_to_buffer);
694 :
695 : /**
696 : * sg_pcopy_from_buffer - Copy from a linear buffer to an SG list
697 : * @sgl: The SG list
698 : * @nents: Number of SG entries
699 : * @buf: Where to copy from
700 : * @skip: Number of bytes to skip before copying
701 : * @buflen: The number of bytes to copy
702 : *
703 : * Returns the number of copied bytes.
704 : *
705 : **/
706 0 : size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
707 : void *buf, size_t buflen, off_t skip)
708 : {
709 0 : return sg_copy_buffer(sgl, nents, buf, buflen, skip, false);
710 : }
711 : EXPORT_SYMBOL(sg_pcopy_from_buffer);
712 :
713 : /**
714 : * sg_pcopy_to_buffer - Copy from an SG list to a linear buffer
715 : * @sgl: The SG list
716 : * @nents: Number of SG entries
717 : * @buf: Where to copy to
718 : * @skip: Number of bytes to skip before copying
719 : * @buflen: The number of bytes to copy
720 : *
721 : * Returns the number of copied bytes.
722 : *
723 : **/
724 0 : size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
725 : void *buf, size_t buflen, off_t skip)
726 : {
727 0 : return sg_copy_buffer(sgl, nents, buf, buflen, skip, true);
728 : }
729 : EXPORT_SYMBOL(sg_pcopy_to_buffer);
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