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Jens Axboe0db92992007-11-30 09:16:50 +01001/*
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 */
Paul Gortmaker8bc3bcc2011-11-16 21:29:17 -05009#include <linux/export.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090010#include <linux/slab.h>
Jens Axboe0db92992007-11-30 09:16:50 +010011#include <linux/scatterlist.h>
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +090012#include <linux/highmem.h>
Chris Wilsonb94de9b2010-07-28 22:59:02 +010013#include <linux/kmemleak.h>
Jens Axboe0db92992007-11-30 09:16:50 +010014
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 **/
25struct scatterlist *sg_next(struct scatterlist *sg)
26{
27#ifdef CONFIG_DEBUG_SG
28 BUG_ON(sg->sg_magic != SG_MAGIC);
29#endif
30 if (sg_is_last(sg))
31 return NULL;
32
33 sg++;
34 if (unlikely(sg_is_chain(sg)))
35 sg = sg_chain_ptr(sg);
36
37 return sg;
38}
39EXPORT_SYMBOL(sg_next);
40
41/**
Maxim Levitsky2e484612012-09-27 12:45:28 +020042 * 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 **/
50int sg_nents(struct scatterlist *sg)
51{
Maxim Levitsky232f1b52012-09-28 10:38:15 +020052 int nents;
53 for (nents = 0; sg; sg = sg_next(sg))
Maxim Levitsky2e484612012-09-27 12:45:28 +020054 nents++;
Maxim Levitsky2e484612012-09-27 12:45:28 +020055 return nents;
56}
57EXPORT_SYMBOL(sg_nents);
58
Tom Lendackycfaed102015-06-01 11:15:25 -050059/**
60 * sg_nents_for_len - return total count of entries in scatterlist
61 * needed to satisfy the supplied length
62 * @sg: The scatterlist
63 * @len: The total required length
64 *
65 * Description:
66 * Determines the number of entries in sg that are required to meet
67 * the supplied length, taking into acount chaining as well
68 *
69 * Returns:
70 * the number of sg entries needed, negative error on failure
71 *
72 **/
73int sg_nents_for_len(struct scatterlist *sg, u64 len)
74{
75 int nents;
76 u64 total;
77
78 if (!len)
79 return 0;
80
81 for (nents = 0, total = 0; sg; sg = sg_next(sg)) {
82 nents++;
83 total += sg->length;
84 if (total >= len)
85 return nents;
86 }
87
88 return -EINVAL;
89}
90EXPORT_SYMBOL(sg_nents_for_len);
Maxim Levitsky2e484612012-09-27 12:45:28 +020091
92/**
Jens Axboe0db92992007-11-30 09:16:50 +010093 * sg_last - return the last scatterlist entry in a list
94 * @sgl: First entry in the scatterlist
95 * @nents: Number of entries in the scatterlist
96 *
97 * Description:
98 * Should only be used casually, it (currently) scans the entire list
99 * to get the last entry.
100 *
101 * Note that the @sgl@ pointer passed in need not be the first one,
102 * the important bit is that @nents@ denotes the number of entries that
103 * exist from @sgl@.
104 *
105 **/
106struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents)
107{
Laura Abbott308c09f2014-08-08 14:23:25 -0700108#ifndef CONFIG_ARCH_HAS_SG_CHAIN
Jens Axboe0db92992007-11-30 09:16:50 +0100109 struct scatterlist *ret = &sgl[nents - 1];
110#else
111 struct scatterlist *sg, *ret = NULL;
112 unsigned int i;
113
114 for_each_sg(sgl, sg, nents, i)
115 ret = sg;
116
117#endif
118#ifdef CONFIG_DEBUG_SG
119 BUG_ON(sgl[0].sg_magic != SG_MAGIC);
120 BUG_ON(!sg_is_last(ret));
121#endif
122 return ret;
123}
124EXPORT_SYMBOL(sg_last);
125
126/**
127 * sg_init_table - Initialize SG table
128 * @sgl: The SG table
129 * @nents: Number of entries in table
130 *
131 * Notes:
132 * If this is part of a chained sg table, sg_mark_end() should be
133 * used only on the last table part.
134 *
135 **/
136void sg_init_table(struct scatterlist *sgl, unsigned int nents)
137{
138 memset(sgl, 0, sizeof(*sgl) * nents);
139#ifdef CONFIG_DEBUG_SG
140 {
141 unsigned int i;
142 for (i = 0; i < nents; i++)
143 sgl[i].sg_magic = SG_MAGIC;
144 }
145#endif
146 sg_mark_end(&sgl[nents - 1]);
147}
148EXPORT_SYMBOL(sg_init_table);
149
150/**
151 * sg_init_one - Initialize a single entry sg list
152 * @sg: SG entry
153 * @buf: Virtual address for IO
154 * @buflen: IO length
155 *
156 **/
157void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen)
158{
159 sg_init_table(sg, 1);
160 sg_set_buf(sg, buf, buflen);
161}
162EXPORT_SYMBOL(sg_init_one);
163
164/*
165 * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree
166 * helpers.
167 */
168static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
169{
Chris Wilsonb94de9b2010-07-28 22:59:02 +0100170 if (nents == SG_MAX_SINGLE_ALLOC) {
171 /*
172 * Kmemleak doesn't track page allocations as they are not
173 * commonly used (in a raw form) for kernel data structures.
174 * As we chain together a list of pages and then a normal
175 * kmalloc (tracked by kmemleak), in order to for that last
176 * allocation not to become decoupled (and thus a
177 * false-positive) we need to inform kmemleak of all the
178 * intermediate allocations.
179 */
180 void *ptr = (void *) __get_free_page(gfp_mask);
181 kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask);
182 return ptr;
183 } else
Jens Axboe0db92992007-11-30 09:16:50 +0100184 return kmalloc(nents * sizeof(struct scatterlist), gfp_mask);
185}
186
187static void sg_kfree(struct scatterlist *sg, unsigned int nents)
188{
Chris Wilsonb94de9b2010-07-28 22:59:02 +0100189 if (nents == SG_MAX_SINGLE_ALLOC) {
190 kmemleak_free(sg);
Jens Axboe0db92992007-11-30 09:16:50 +0100191 free_page((unsigned long) sg);
Chris Wilsonb94de9b2010-07-28 22:59:02 +0100192 } else
Jens Axboe0db92992007-11-30 09:16:50 +0100193 kfree(sg);
194}
195
196/**
197 * __sg_free_table - Free a previously mapped sg table
198 * @table: The sg table header to use
James Bottomley7cedb1f2008-01-13 14:15:28 -0600199 * @max_ents: The maximum number of entries per single scatterlist
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200200 * @skip_first_chunk: don't free the (preallocated) first scatterlist chunk
Jens Axboe0db92992007-11-30 09:16:50 +0100201 * @free_fn: Free function
202 *
203 * Description:
James Bottomley7cedb1f2008-01-13 14:15:28 -0600204 * Free an sg table previously allocated and setup with
205 * __sg_alloc_table(). The @max_ents value must be identical to
206 * that previously used with __sg_alloc_table().
Jens Axboe0db92992007-11-30 09:16:50 +0100207 *
208 **/
James Bottomley7cedb1f2008-01-13 14:15:28 -0600209void __sg_free_table(struct sg_table *table, unsigned int max_ents,
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200210 bool skip_first_chunk, sg_free_fn *free_fn)
Jens Axboe0db92992007-11-30 09:16:50 +0100211{
212 struct scatterlist *sgl, *next;
213
214 if (unlikely(!table->sgl))
215 return;
216
217 sgl = table->sgl;
218 while (table->orig_nents) {
219 unsigned int alloc_size = table->orig_nents;
220 unsigned int sg_size;
221
222 /*
James Bottomley7cedb1f2008-01-13 14:15:28 -0600223 * If we have more than max_ents segments left,
Jens Axboe0db92992007-11-30 09:16:50 +0100224 * then assign 'next' to the sg table after the current one.
225 * sg_size is then one less than alloc size, since the last
226 * element is the chain pointer.
227 */
James Bottomley7cedb1f2008-01-13 14:15:28 -0600228 if (alloc_size > max_ents) {
229 next = sg_chain_ptr(&sgl[max_ents - 1]);
230 alloc_size = max_ents;
Jens Axboe0db92992007-11-30 09:16:50 +0100231 sg_size = alloc_size - 1;
232 } else {
233 sg_size = alloc_size;
234 next = NULL;
235 }
236
237 table->orig_nents -= sg_size;
Tony Battersbyc21e59d2014-10-23 15:10:21 -0400238 if (skip_first_chunk)
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200239 skip_first_chunk = false;
Tony Battersbyc21e59d2014-10-23 15:10:21 -0400240 else
241 free_fn(sgl, alloc_size);
Jens Axboe0db92992007-11-30 09:16:50 +0100242 sgl = next;
243 }
244
245 table->sgl = NULL;
246}
247EXPORT_SYMBOL(__sg_free_table);
248
249/**
250 * sg_free_table - Free a previously allocated sg table
251 * @table: The mapped sg table header
252 *
253 **/
254void sg_free_table(struct sg_table *table)
255{
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200256 __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);
Jens Axboe0db92992007-11-30 09:16:50 +0100257}
258EXPORT_SYMBOL(sg_free_table);
259
260/**
261 * __sg_alloc_table - Allocate and initialize an sg table with given allocator
262 * @table: The sg table header to use
263 * @nents: Number of entries in sg list
James Bottomley7cedb1f2008-01-13 14:15:28 -0600264 * @max_ents: The maximum number of entries the allocator returns per call
Jens Axboe0db92992007-11-30 09:16:50 +0100265 * @gfp_mask: GFP allocation mask
266 * @alloc_fn: Allocator to use
267 *
James Bottomley7cedb1f2008-01-13 14:15:28 -0600268 * Description:
269 * This function returns a @table @nents long. The allocator is
270 * defined to return scatterlist chunks of maximum size @max_ents.
271 * Thus if @nents is bigger than @max_ents, the scatterlists will be
272 * chained in units of @max_ents.
273 *
Jens Axboe0db92992007-11-30 09:16:50 +0100274 * Notes:
275 * If this function returns non-0 (eg failure), the caller must call
276 * __sg_free_table() to cleanup any leftover allocations.
277 *
278 **/
James Bottomley7cedb1f2008-01-13 14:15:28 -0600279int __sg_alloc_table(struct sg_table *table, unsigned int nents,
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200280 unsigned int max_ents, struct scatterlist *first_chunk,
281 gfp_t gfp_mask, sg_alloc_fn *alloc_fn)
Jens Axboe0db92992007-11-30 09:16:50 +0100282{
283 struct scatterlist *sg, *prv;
284 unsigned int left;
285
Dan Carpenter27daabd2013-07-08 16:01:58 -0700286 memset(table, 0, sizeof(*table));
287
288 if (nents == 0)
289 return -EINVAL;
Laura Abbott308c09f2014-08-08 14:23:25 -0700290#ifndef CONFIG_ARCH_HAS_SG_CHAIN
Nick Bowler6fd59a82012-12-17 16:05:20 -0800291 if (WARN_ON_ONCE(nents > max_ents))
292 return -EINVAL;
Jens Axboe0db92992007-11-30 09:16:50 +0100293#endif
294
Jens Axboe0db92992007-11-30 09:16:50 +0100295 left = nents;
296 prv = NULL;
297 do {
298 unsigned int sg_size, alloc_size = left;
299
James Bottomley7cedb1f2008-01-13 14:15:28 -0600300 if (alloc_size > max_ents) {
301 alloc_size = max_ents;
Jens Axboe0db92992007-11-30 09:16:50 +0100302 sg_size = alloc_size - 1;
303 } else
304 sg_size = alloc_size;
305
306 left -= sg_size;
307
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200308 if (first_chunk) {
309 sg = first_chunk;
310 first_chunk = NULL;
311 } else {
312 sg = alloc_fn(alloc_size, gfp_mask);
313 }
Jeffrey Carlyleedce6822010-08-30 19:55:09 +0200314 if (unlikely(!sg)) {
315 /*
316 * Adjust entry count to reflect that the last
317 * entry of the previous table won't be used for
318 * linkage. Without this, sg_kfree() may get
319 * confused.
320 */
321 if (prv)
322 table->nents = ++table->orig_nents;
323
324 return -ENOMEM;
325 }
Jens Axboe0db92992007-11-30 09:16:50 +0100326
327 sg_init_table(sg, alloc_size);
328 table->nents = table->orig_nents += sg_size;
329
330 /*
331 * If this is the first mapping, assign the sg table header.
332 * If this is not the first mapping, chain previous part.
333 */
334 if (prv)
James Bottomley7cedb1f2008-01-13 14:15:28 -0600335 sg_chain(prv, max_ents, sg);
Jens Axboe0db92992007-11-30 09:16:50 +0100336 else
337 table->sgl = sg;
338
339 /*
340 * If no more entries after this one, mark the end
341 */
342 if (!left)
343 sg_mark_end(&sg[sg_size - 1]);
344
Jens Axboe0db92992007-11-30 09:16:50 +0100345 prv = sg;
346 } while (left);
347
348 return 0;
349}
350EXPORT_SYMBOL(__sg_alloc_table);
351
352/**
353 * sg_alloc_table - Allocate and initialize an sg table
354 * @table: The sg table header to use
355 * @nents: Number of entries in sg list
356 * @gfp_mask: GFP allocation mask
357 *
358 * Description:
359 * Allocate and initialize an sg table. If @nents@ is larger than
360 * SG_MAX_SINGLE_ALLOC a chained sg table will be setup.
361 *
362 **/
363int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
364{
365 int ret;
366
James Bottomley7cedb1f2008-01-13 14:15:28 -0600367 ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200368 NULL, gfp_mask, sg_kmalloc);
Jens Axboe0db92992007-11-30 09:16:50 +0100369 if (unlikely(ret))
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200370 __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);
Jens Axboe0db92992007-11-30 09:16:50 +0100371
372 return ret;
373}
374EXPORT_SYMBOL(sg_alloc_table);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900375
376/**
Tomasz Stanislawskiefc42bc2012-06-18 09:25:01 +0200377 * sg_alloc_table_from_pages - Allocate and initialize an sg table from
378 * an array of pages
379 * @sgt: The sg table header to use
380 * @pages: Pointer to an array of page pointers
381 * @n_pages: Number of pages in the pages array
382 * @offset: Offset from start of the first page to the start of a buffer
383 * @size: Number of valid bytes in the buffer (after offset)
384 * @gfp_mask: GFP allocation mask
385 *
386 * Description:
387 * Allocate and initialize an sg table from a list of pages. Contiguous
388 * ranges of the pages are squashed into a single scatterlist node. A user
389 * may provide an offset at a start and a size of valid data in a buffer
390 * specified by the page array. The returned sg table is released by
391 * sg_free_table.
392 *
393 * Returns:
394 * 0 on success, negative error on failure
395 */
396int sg_alloc_table_from_pages(struct sg_table *sgt,
397 struct page **pages, unsigned int n_pages,
398 unsigned long offset, unsigned long size,
399 gfp_t gfp_mask)
400{
401 unsigned int chunks;
402 unsigned int i;
403 unsigned int cur_page;
404 int ret;
405 struct scatterlist *s;
406
407 /* compute number of contiguous chunks */
408 chunks = 1;
409 for (i = 1; i < n_pages; ++i)
410 if (page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1)
411 ++chunks;
412
413 ret = sg_alloc_table(sgt, chunks, gfp_mask);
414 if (unlikely(ret))
415 return ret;
416
417 /* merging chunks and putting them into the scatterlist */
418 cur_page = 0;
419 for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
420 unsigned long chunk_size;
421 unsigned int j;
422
423 /* look for the end of the current chunk */
424 for (j = cur_page + 1; j < n_pages; ++j)
425 if (page_to_pfn(pages[j]) !=
426 page_to_pfn(pages[j - 1]) + 1)
427 break;
428
429 chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset;
430 sg_set_page(s, pages[cur_page], min(size, chunk_size), offset);
431 size -= chunk_size;
432 offset = 0;
433 cur_page = j;
434 }
435
436 return 0;
437}
438EXPORT_SYMBOL(sg_alloc_table_from_pages);
439
Imre Deaka321e912013-02-27 17:02:56 -0800440void __sg_page_iter_start(struct sg_page_iter *piter,
441 struct scatterlist *sglist, unsigned int nents,
442 unsigned long pgoffset)
443{
444 piter->__pg_advance = 0;
445 piter->__nents = nents;
446
Imre Deaka321e912013-02-27 17:02:56 -0800447 piter->sg = sglist;
448 piter->sg_pgoffset = pgoffset;
449}
450EXPORT_SYMBOL(__sg_page_iter_start);
451
452static int sg_page_count(struct scatterlist *sg)
453{
454 return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT;
455}
456
457bool __sg_page_iter_next(struct sg_page_iter *piter)
458{
459 if (!piter->__nents || !piter->sg)
460 return false;
461
462 piter->sg_pgoffset += piter->__pg_advance;
463 piter->__pg_advance = 1;
464
465 while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {
466 piter->sg_pgoffset -= sg_page_count(piter->sg);
467 piter->sg = sg_next(piter->sg);
468 if (!--piter->__nents || !piter->sg)
469 return false;
470 }
Imre Deaka321e912013-02-27 17:02:56 -0800471
472 return true;
473}
474EXPORT_SYMBOL(__sg_page_iter_next);
475
Tomasz Stanislawskiefc42bc2012-06-18 09:25:01 +0200476/**
Tejun Heo137d3ed2008-07-19 23:03:35 +0900477 * sg_miter_start - start mapping iteration over a sg list
478 * @miter: sg mapping iter to be started
479 * @sgl: sg list to iterate over
480 * @nents: number of sg entries
481 *
482 * Description:
483 * Starts mapping iterator @miter.
484 *
485 * Context:
486 * Don't care.
487 */
488void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
489 unsigned int nents, unsigned int flags)
490{
491 memset(miter, 0, sizeof(struct sg_mapping_iter));
492
Imre Deak4225fc82013-02-27 17:02:57 -0800493 __sg_page_iter_start(&miter->piter, sgl, nents, 0);
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200494 WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG)));
Tejun Heo137d3ed2008-07-19 23:03:35 +0900495 miter->__flags = flags;
496}
497EXPORT_SYMBOL(sg_miter_start);
498
Akinobu Mita11052002013-07-08 16:01:52 -0700499static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)
500{
501 if (!miter->__remaining) {
502 struct scatterlist *sg;
503 unsigned long pgoffset;
504
505 if (!__sg_page_iter_next(&miter->piter))
506 return false;
507
508 sg = miter->piter.sg;
509 pgoffset = miter->piter.sg_pgoffset;
510
511 miter->__offset = pgoffset ? 0 : sg->offset;
512 miter->__remaining = sg->offset + sg->length -
513 (pgoffset << PAGE_SHIFT) - miter->__offset;
514 miter->__remaining = min_t(unsigned long, miter->__remaining,
515 PAGE_SIZE - miter->__offset);
516 }
517
518 return true;
519}
520
Tejun Heo137d3ed2008-07-19 23:03:35 +0900521/**
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700522 * sg_miter_skip - reposition mapping iterator
523 * @miter: sg mapping iter to be skipped
524 * @offset: number of bytes to plus the current location
525 *
526 * Description:
527 * Sets the offset of @miter to its current location plus @offset bytes.
528 * If mapping iterator @miter has been proceeded by sg_miter_next(), this
529 * stops @miter.
530 *
531 * Context:
532 * Don't care if @miter is stopped, or not proceeded yet.
533 * Otherwise, preemption disabled if the SG_MITER_ATOMIC is set.
534 *
535 * Returns:
536 * true if @miter contains the valid mapping. false if end of sg
537 * list is reached.
538 */
Ming Lei0d6077f2013-11-26 12:43:37 +0800539bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset)
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700540{
541 sg_miter_stop(miter);
542
543 while (offset) {
544 off_t consumed;
545
546 if (!sg_miter_get_next_page(miter))
547 return false;
548
549 consumed = min_t(off_t, offset, miter->__remaining);
550 miter->__offset += consumed;
551 miter->__remaining -= consumed;
552 offset -= consumed;
553 }
554
555 return true;
556}
Ming Lei0d6077f2013-11-26 12:43:37 +0800557EXPORT_SYMBOL(sg_miter_skip);
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700558
559/**
Tejun Heo137d3ed2008-07-19 23:03:35 +0900560 * sg_miter_next - proceed mapping iterator to the next mapping
561 * @miter: sg mapping iter to proceed
562 *
563 * Description:
Tejun Heo8290e2d2012-10-04 17:13:28 -0700564 * Proceeds @miter to the next mapping. @miter should have been started
565 * using sg_miter_start(). On successful return, @miter->page,
566 * @miter->addr and @miter->length point to the current mapping.
Tejun Heo137d3ed2008-07-19 23:03:35 +0900567 *
568 * Context:
Tejun Heo8290e2d2012-10-04 17:13:28 -0700569 * Preemption disabled if SG_MITER_ATOMIC. Preemption must stay disabled
570 * till @miter is stopped. May sleep if !SG_MITER_ATOMIC.
Tejun Heo137d3ed2008-07-19 23:03:35 +0900571 *
572 * Returns:
573 * true if @miter contains the next mapping. false if end of sg
574 * list is reached.
575 */
576bool sg_miter_next(struct sg_mapping_iter *miter)
577{
Tejun Heo137d3ed2008-07-19 23:03:35 +0900578 sg_miter_stop(miter);
579
Imre Deak4225fc82013-02-27 17:02:57 -0800580 /*
581 * Get to the next page if necessary.
582 * __remaining, __offset is adjusted by sg_miter_stop
583 */
Akinobu Mita11052002013-07-08 16:01:52 -0700584 if (!sg_miter_get_next_page(miter))
585 return false;
Imre Deak4225fc82013-02-27 17:02:57 -0800586
Imre Deak2db76d72013-03-26 15:14:18 +0200587 miter->page = sg_page_iter_page(&miter->piter);
Imre Deak4225fc82013-02-27 17:02:57 -0800588 miter->consumed = miter->length = miter->__remaining;
Tejun Heo137d3ed2008-07-19 23:03:35 +0900589
590 if (miter->__flags & SG_MITER_ATOMIC)
Imre Deak4225fc82013-02-27 17:02:57 -0800591 miter->addr = kmap_atomic(miter->page) + miter->__offset;
Tejun Heo137d3ed2008-07-19 23:03:35 +0900592 else
Imre Deak4225fc82013-02-27 17:02:57 -0800593 miter->addr = kmap(miter->page) + miter->__offset;
Tejun Heo137d3ed2008-07-19 23:03:35 +0900594
595 return true;
596}
597EXPORT_SYMBOL(sg_miter_next);
598
599/**
600 * sg_miter_stop - stop mapping iteration
601 * @miter: sg mapping iter to be stopped
602 *
603 * Description:
604 * Stops mapping iterator @miter. @miter should have been started
605 * started using sg_miter_start(). A stopped iteration can be
606 * resumed by calling sg_miter_next() on it. This is useful when
607 * resources (kmap) need to be released during iteration.
608 *
609 * Context:
Tejun Heo8290e2d2012-10-04 17:13:28 -0700610 * Preemption disabled if the SG_MITER_ATOMIC is set. Don't care
611 * otherwise.
Tejun Heo137d3ed2008-07-19 23:03:35 +0900612 */
613void sg_miter_stop(struct sg_mapping_iter *miter)
614{
615 WARN_ON(miter->consumed > miter->length);
616
617 /* drop resources from the last iteration */
618 if (miter->addr) {
619 miter->__offset += miter->consumed;
Imre Deak4225fc82013-02-27 17:02:57 -0800620 miter->__remaining -= miter->consumed;
Tejun Heo137d3ed2008-07-19 23:03:35 +0900621
Ming Lei3d77b502013-10-31 16:34:17 -0700622 if ((miter->__flags & SG_MITER_TO_SG) &&
623 !PageSlab(miter->page))
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200624 flush_kernel_dcache_page(miter->page);
625
Tejun Heo137d3ed2008-07-19 23:03:35 +0900626 if (miter->__flags & SG_MITER_ATOMIC) {
Tejun Heo8290e2d2012-10-04 17:13:28 -0700627 WARN_ON_ONCE(preemptible());
Cong Wangc3eede82011-11-25 23:14:39 +0800628 kunmap_atomic(miter->addr);
Tejun Heo137d3ed2008-07-19 23:03:35 +0900629 } else
Arjan van de Venf652c522008-11-19 15:36:19 -0800630 kunmap(miter->page);
Tejun Heo137d3ed2008-07-19 23:03:35 +0900631
632 miter->page = NULL;
633 miter->addr = NULL;
634 miter->length = 0;
635 miter->consumed = 0;
636 }
637}
638EXPORT_SYMBOL(sg_miter_stop);
639
640/**
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900641 * sg_copy_buffer - Copy data between a linear buffer and an SG list
642 * @sgl: The SG list
643 * @nents: Number of SG entries
644 * @buf: Where to copy from
645 * @buflen: The number of bytes to copy
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700646 * @skip: Number of bytes to skip before copying
647 * @to_buffer: transfer direction (true == from an sg list to a
648 * buffer, false == from a buffer to an sg list
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900649 *
650 * Returns the number of copied bytes.
651 *
652 **/
Dave Gordon386ecb12015-06-30 14:58:57 -0700653size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
654 size_t buflen, off_t skip, bool to_buffer)
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900655{
Tejun Heo137d3ed2008-07-19 23:03:35 +0900656 unsigned int offset = 0;
657 struct sg_mapping_iter miter;
FUJITA Tomonori50bed2e2008-09-11 18:35:39 +0200658 unsigned long flags;
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200659 unsigned int sg_flags = SG_MITER_ATOMIC;
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900660
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200661 if (to_buffer)
662 sg_flags |= SG_MITER_FROM_SG;
663 else
664 sg_flags |= SG_MITER_TO_SG;
665
666 sg_miter_start(&miter, sgl, nents, sg_flags);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900667
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700668 if (!sg_miter_skip(&miter, skip))
669 return false;
670
FUJITA Tomonori50bed2e2008-09-11 18:35:39 +0200671 local_irq_save(flags);
672
Tejun Heo137d3ed2008-07-19 23:03:35 +0900673 while (sg_miter_next(&miter) && offset < buflen) {
674 unsigned int len;
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900675
Tejun Heo137d3ed2008-07-19 23:03:35 +0900676 len = min(miter.length, buflen - offset);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900677
Tejun Heo137d3ed2008-07-19 23:03:35 +0900678 if (to_buffer)
679 memcpy(buf + offset, miter.addr, len);
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200680 else
Tejun Heo137d3ed2008-07-19 23:03:35 +0900681 memcpy(miter.addr, buf + offset, len);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900682
Tejun Heo137d3ed2008-07-19 23:03:35 +0900683 offset += len;
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900684 }
685
Tejun Heo137d3ed2008-07-19 23:03:35 +0900686 sg_miter_stop(&miter);
687
FUJITA Tomonori50bed2e2008-09-11 18:35:39 +0200688 local_irq_restore(flags);
Tejun Heo137d3ed2008-07-19 23:03:35 +0900689 return offset;
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900690}
Dave Gordon386ecb12015-06-30 14:58:57 -0700691EXPORT_SYMBOL(sg_copy_buffer);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900692
693/**
694 * sg_copy_from_buffer - Copy from a linear buffer to an SG list
695 * @sgl: The SG list
696 * @nents: Number of SG entries
697 * @buf: Where to copy from
698 * @buflen: The number of bytes to copy
699 *
700 * Returns the number of copied bytes.
701 *
702 **/
703size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
Dave Gordon2a1bf8f2015-06-30 14:58:54 -0700704 const void *buf, size_t buflen)
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900705{
Dave Gordon2a1bf8f2015-06-30 14:58:54 -0700706 return sg_copy_buffer(sgl, nents, (void *)buf, buflen, 0, false);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900707}
708EXPORT_SYMBOL(sg_copy_from_buffer);
709
710/**
711 * sg_copy_to_buffer - Copy from an SG list to a linear buffer
712 * @sgl: The SG list
713 * @nents: Number of SG entries
714 * @buf: Where to copy to
715 * @buflen: The number of bytes to copy
716 *
717 * Returns the number of copied bytes.
718 *
719 **/
720size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
721 void *buf, size_t buflen)
722{
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700723 return sg_copy_buffer(sgl, nents, buf, buflen, 0, true);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900724}
725EXPORT_SYMBOL(sg_copy_to_buffer);
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700726
727/**
728 * sg_pcopy_from_buffer - Copy from a linear buffer to an SG list
729 * @sgl: The SG list
730 * @nents: Number of SG entries
731 * @buf: Where to copy from
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700732 * @buflen: The number of bytes to copy
Dave Gordon4dc7daf2015-06-30 14:58:52 -0700733 * @skip: Number of bytes to skip before copying
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700734 *
735 * Returns the number of copied bytes.
736 *
737 **/
738size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
Dave Gordon2a1bf8f2015-06-30 14:58:54 -0700739 const void *buf, size_t buflen, off_t skip)
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700740{
Dave Gordon2a1bf8f2015-06-30 14:58:54 -0700741 return sg_copy_buffer(sgl, nents, (void *)buf, buflen, skip, false);
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700742}
743EXPORT_SYMBOL(sg_pcopy_from_buffer);
744
745/**
746 * sg_pcopy_to_buffer - Copy from an SG list to a linear buffer
747 * @sgl: The SG list
748 * @nents: Number of SG entries
749 * @buf: Where to copy to
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700750 * @buflen: The number of bytes to copy
Dave Gordon4dc7daf2015-06-30 14:58:52 -0700751 * @skip: Number of bytes to skip before copying
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700752 *
753 * Returns the number of copied bytes.
754 *
755 **/
756size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
757 void *buf, size_t buflen, off_t skip)
758{
759 return sg_copy_buffer(sgl, nents, buf, buflen, skip, true);
760}
761EXPORT_SYMBOL(sg_pcopy_to_buffer);