blob: 7c1c55f7daaa832df2aef731cd218d4ed80f44dc [file] [log] [blame]
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{
Jens Axboe0db92992007-11-30 09:16:50 +0100108 struct scatterlist *sg, *ret = NULL;
109 unsigned int i;
110
111 for_each_sg(sgl, sg, nents, i)
112 ret = sg;
113
Jens Axboe0db92992007-11-30 09:16:50 +0100114#ifdef CONFIG_DEBUG_SG
115 BUG_ON(sgl[0].sg_magic != SG_MAGIC);
116 BUG_ON(!sg_is_last(ret));
117#endif
118 return ret;
119}
120EXPORT_SYMBOL(sg_last);
121
122/**
123 * sg_init_table - Initialize SG table
124 * @sgl: The SG table
125 * @nents: Number of entries in table
126 *
127 * Notes:
128 * If this is part of a chained sg table, sg_mark_end() should be
129 * used only on the last table part.
130 *
131 **/
132void sg_init_table(struct scatterlist *sgl, unsigned int nents)
133{
134 memset(sgl, 0, sizeof(*sgl) * nents);
135#ifdef CONFIG_DEBUG_SG
136 {
137 unsigned int i;
138 for (i = 0; i < nents; i++)
139 sgl[i].sg_magic = SG_MAGIC;
140 }
141#endif
142 sg_mark_end(&sgl[nents - 1]);
143}
144EXPORT_SYMBOL(sg_init_table);
145
146/**
147 * sg_init_one - Initialize a single entry sg list
148 * @sg: SG entry
149 * @buf: Virtual address for IO
150 * @buflen: IO length
151 *
152 **/
153void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen)
154{
155 sg_init_table(sg, 1);
156 sg_set_buf(sg, buf, buflen);
157}
158EXPORT_SYMBOL(sg_init_one);
159
160/*
161 * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree
162 * helpers.
163 */
164static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
165{
Chris Wilsonb94de9b2010-07-28 22:59:02 +0100166 if (nents == SG_MAX_SINGLE_ALLOC) {
167 /*
168 * Kmemleak doesn't track page allocations as they are not
169 * commonly used (in a raw form) for kernel data structures.
170 * As we chain together a list of pages and then a normal
171 * kmalloc (tracked by kmemleak), in order to for that last
172 * allocation not to become decoupled (and thus a
173 * false-positive) we need to inform kmemleak of all the
174 * intermediate allocations.
175 */
176 void *ptr = (void *) __get_free_page(gfp_mask);
177 kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask);
178 return ptr;
179 } else
Jens Axboe0db92992007-11-30 09:16:50 +0100180 return kmalloc(nents * sizeof(struct scatterlist), gfp_mask);
181}
182
183static void sg_kfree(struct scatterlist *sg, unsigned int nents)
184{
Chris Wilsonb94de9b2010-07-28 22:59:02 +0100185 if (nents == SG_MAX_SINGLE_ALLOC) {
186 kmemleak_free(sg);
Jens Axboe0db92992007-11-30 09:16:50 +0100187 free_page((unsigned long) sg);
Chris Wilsonb94de9b2010-07-28 22:59:02 +0100188 } else
Jens Axboe0db92992007-11-30 09:16:50 +0100189 kfree(sg);
190}
191
192/**
193 * __sg_free_table - Free a previously mapped sg table
194 * @table: The sg table header to use
James Bottomley7cedb1f2008-01-13 14:15:28 -0600195 * @max_ents: The maximum number of entries per single scatterlist
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200196 * @skip_first_chunk: don't free the (preallocated) first scatterlist chunk
Jens Axboe0db92992007-11-30 09:16:50 +0100197 * @free_fn: Free function
198 *
199 * Description:
James Bottomley7cedb1f2008-01-13 14:15:28 -0600200 * Free an sg table previously allocated and setup with
201 * __sg_alloc_table(). The @max_ents value must be identical to
202 * that previously used with __sg_alloc_table().
Jens Axboe0db92992007-11-30 09:16:50 +0100203 *
204 **/
James Bottomley7cedb1f2008-01-13 14:15:28 -0600205void __sg_free_table(struct sg_table *table, unsigned int max_ents,
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200206 bool skip_first_chunk, sg_free_fn *free_fn)
Jens Axboe0db92992007-11-30 09:16:50 +0100207{
208 struct scatterlist *sgl, *next;
209
210 if (unlikely(!table->sgl))
211 return;
212
213 sgl = table->sgl;
214 while (table->orig_nents) {
215 unsigned int alloc_size = table->orig_nents;
216 unsigned int sg_size;
217
218 /*
James Bottomley7cedb1f2008-01-13 14:15:28 -0600219 * If we have more than max_ents segments left,
Jens Axboe0db92992007-11-30 09:16:50 +0100220 * then assign 'next' to the sg table after the current one.
221 * sg_size is then one less than alloc size, since the last
222 * element is the chain pointer.
223 */
James Bottomley7cedb1f2008-01-13 14:15:28 -0600224 if (alloc_size > max_ents) {
225 next = sg_chain_ptr(&sgl[max_ents - 1]);
226 alloc_size = max_ents;
Jens Axboe0db92992007-11-30 09:16:50 +0100227 sg_size = alloc_size - 1;
228 } else {
229 sg_size = alloc_size;
230 next = NULL;
231 }
232
233 table->orig_nents -= sg_size;
Tony Battersbyc21e59d2014-10-23 15:10:21 -0400234 if (skip_first_chunk)
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200235 skip_first_chunk = false;
Tony Battersbyc21e59d2014-10-23 15:10:21 -0400236 else
237 free_fn(sgl, alloc_size);
Jens Axboe0db92992007-11-30 09:16:50 +0100238 sgl = next;
239 }
240
241 table->sgl = NULL;
242}
243EXPORT_SYMBOL(__sg_free_table);
244
245/**
246 * sg_free_table - Free a previously allocated sg table
247 * @table: The mapped sg table header
248 *
249 **/
250void sg_free_table(struct sg_table *table)
251{
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200252 __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);
Jens Axboe0db92992007-11-30 09:16:50 +0100253}
254EXPORT_SYMBOL(sg_free_table);
255
256/**
257 * __sg_alloc_table - Allocate and initialize an sg table with given allocator
258 * @table: The sg table header to use
259 * @nents: Number of entries in sg list
James Bottomley7cedb1f2008-01-13 14:15:28 -0600260 * @max_ents: The maximum number of entries the allocator returns per call
Jens Axboe0db92992007-11-30 09:16:50 +0100261 * @gfp_mask: GFP allocation mask
262 * @alloc_fn: Allocator to use
263 *
James Bottomley7cedb1f2008-01-13 14:15:28 -0600264 * Description:
265 * This function returns a @table @nents long. The allocator is
266 * defined to return scatterlist chunks of maximum size @max_ents.
267 * Thus if @nents is bigger than @max_ents, the scatterlists will be
268 * chained in units of @max_ents.
269 *
Jens Axboe0db92992007-11-30 09:16:50 +0100270 * Notes:
271 * If this function returns non-0 (eg failure), the caller must call
272 * __sg_free_table() to cleanup any leftover allocations.
273 *
274 **/
James Bottomley7cedb1f2008-01-13 14:15:28 -0600275int __sg_alloc_table(struct sg_table *table, unsigned int nents,
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200276 unsigned int max_ents, struct scatterlist *first_chunk,
277 gfp_t gfp_mask, sg_alloc_fn *alloc_fn)
Jens Axboe0db92992007-11-30 09:16:50 +0100278{
279 struct scatterlist *sg, *prv;
280 unsigned int left;
281
Dan Carpenter27daabd2013-07-08 16:01:58 -0700282 memset(table, 0, sizeof(*table));
283
284 if (nents == 0)
285 return -EINVAL;
Laura Abbott308c09f2014-08-08 14:23:25 -0700286#ifndef CONFIG_ARCH_HAS_SG_CHAIN
Nick Bowler6fd59a82012-12-17 16:05:20 -0800287 if (WARN_ON_ONCE(nents > max_ents))
288 return -EINVAL;
Jens Axboe0db92992007-11-30 09:16:50 +0100289#endif
290
Jens Axboe0db92992007-11-30 09:16:50 +0100291 left = nents;
292 prv = NULL;
293 do {
294 unsigned int sg_size, alloc_size = left;
295
James Bottomley7cedb1f2008-01-13 14:15:28 -0600296 if (alloc_size > max_ents) {
297 alloc_size = max_ents;
Jens Axboe0db92992007-11-30 09:16:50 +0100298 sg_size = alloc_size - 1;
299 } else
300 sg_size = alloc_size;
301
302 left -= sg_size;
303
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200304 if (first_chunk) {
305 sg = first_chunk;
306 first_chunk = NULL;
307 } else {
308 sg = alloc_fn(alloc_size, gfp_mask);
309 }
Jeffrey Carlyleedce6822010-08-30 19:55:09 +0200310 if (unlikely(!sg)) {
311 /*
312 * Adjust entry count to reflect that the last
313 * entry of the previous table won't be used for
314 * linkage. Without this, sg_kfree() may get
315 * confused.
316 */
317 if (prv)
318 table->nents = ++table->orig_nents;
319
320 return -ENOMEM;
321 }
Jens Axboe0db92992007-11-30 09:16:50 +0100322
323 sg_init_table(sg, alloc_size);
324 table->nents = table->orig_nents += sg_size;
325
326 /*
327 * If this is the first mapping, assign the sg table header.
328 * If this is not the first mapping, chain previous part.
329 */
330 if (prv)
James Bottomley7cedb1f2008-01-13 14:15:28 -0600331 sg_chain(prv, max_ents, sg);
Jens Axboe0db92992007-11-30 09:16:50 +0100332 else
333 table->sgl = sg;
334
335 /*
336 * If no more entries after this one, mark the end
337 */
338 if (!left)
339 sg_mark_end(&sg[sg_size - 1]);
340
Jens Axboe0db92992007-11-30 09:16:50 +0100341 prv = sg;
342 } while (left);
343
344 return 0;
345}
346EXPORT_SYMBOL(__sg_alloc_table);
347
348/**
349 * sg_alloc_table - Allocate and initialize an sg table
350 * @table: The sg table header to use
351 * @nents: Number of entries in sg list
352 * @gfp_mask: GFP allocation mask
353 *
354 * Description:
355 * Allocate and initialize an sg table. If @nents@ is larger than
356 * SG_MAX_SINGLE_ALLOC a chained sg table will be setup.
357 *
358 **/
359int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
360{
361 int ret;
362
James Bottomley7cedb1f2008-01-13 14:15:28 -0600363 ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200364 NULL, gfp_mask, sg_kmalloc);
Jens Axboe0db92992007-11-30 09:16:50 +0100365 if (unlikely(ret))
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200366 __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);
Jens Axboe0db92992007-11-30 09:16:50 +0100367
368 return ret;
369}
370EXPORT_SYMBOL(sg_alloc_table);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900371
372/**
Tvrtko Ursulin89d85892017-08-03 10:13:51 +0100373 * __sg_alloc_table_from_pages - Allocate and initialize an sg table from
374 * an array of pages
375 * @sgt: The sg table header to use
376 * @pages: Pointer to an array of page pointers
377 * @n_pages: Number of pages in the pages array
378 * @offset: Offset from start of the first page to the start of a buffer
379 * @size: Number of valid bytes in the buffer (after offset)
380 * @max_segment: Maximum size of a scatterlist node in bytes (page aligned)
381 * @gfp_mask: GFP allocation mask
Tomasz Stanislawskiefc42bc2012-06-18 09:25:01 +0200382 *
383 * Description:
384 * Allocate and initialize an sg table from a list of pages. Contiguous
Tvrtko Ursulin89d85892017-08-03 10:13:51 +0100385 * ranges of the pages are squashed into a single scatterlist node up to the
386 * maximum size specified in @max_segment. An user may provide an offset at a
387 * start and a size of valid data in a buffer specified by the page array.
388 * The returned sg table is released by sg_free_table.
Tomasz Stanislawskiefc42bc2012-06-18 09:25:01 +0200389 *
390 * Returns:
391 * 0 on success, negative error on failure
392 */
Tvrtko Ursulin89d85892017-08-03 10:13:51 +0100393int __sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages,
394 unsigned int n_pages, unsigned int offset,
395 unsigned long size, unsigned int max_segment,
396 gfp_t gfp_mask)
Tomasz Stanislawskiefc42bc2012-06-18 09:25:01 +0200397{
Tvrtko Ursulinc1259062017-08-03 10:13:12 +0100398 unsigned int chunks, cur_page, seg_len, i;
Tomasz Stanislawskiefc42bc2012-06-18 09:25:01 +0200399 int ret;
400 struct scatterlist *s;
401
Tvrtko Ursulin89d85892017-08-03 10:13:51 +0100402 if (WARN_ON(!max_segment || offset_in_page(max_segment)))
403 return -EINVAL;
404
Tomasz Stanislawskiefc42bc2012-06-18 09:25:01 +0200405 /* compute number of contiguous chunks */
406 chunks = 1;
Tvrtko Ursulinc1259062017-08-03 10:13:12 +0100407 seg_len = 0;
408 for (i = 1; i < n_pages; i++) {
409 seg_len += PAGE_SIZE;
410 if (seg_len >= max_segment ||
411 page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1) {
412 chunks++;
413 seg_len = 0;
414 }
415 }
Tomasz Stanislawskiefc42bc2012-06-18 09:25:01 +0200416
417 ret = sg_alloc_table(sgt, chunks, gfp_mask);
418 if (unlikely(ret))
419 return ret;
420
421 /* merging chunks and putting them into the scatterlist */
422 cur_page = 0;
423 for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
Tvrtko Ursulinc1259062017-08-03 10:13:12 +0100424 unsigned int j, chunk_size;
Tomasz Stanislawskiefc42bc2012-06-18 09:25:01 +0200425
426 /* look for the end of the current chunk */
Tvrtko Ursulinc1259062017-08-03 10:13:12 +0100427 seg_len = 0;
428 for (j = cur_page + 1; j < n_pages; j++) {
429 seg_len += PAGE_SIZE;
430 if (seg_len >= max_segment ||
431 page_to_pfn(pages[j]) !=
Tomasz Stanislawskiefc42bc2012-06-18 09:25:01 +0200432 page_to_pfn(pages[j - 1]) + 1)
433 break;
Tvrtko Ursulinc1259062017-08-03 10:13:12 +0100434 }
Tomasz Stanislawskiefc42bc2012-06-18 09:25:01 +0200435
436 chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset;
Tvrtko Ursulinc1259062017-08-03 10:13:12 +0100437 sg_set_page(s, pages[cur_page],
438 min_t(unsigned long, size, chunk_size), offset);
Tomasz Stanislawskiefc42bc2012-06-18 09:25:01 +0200439 size -= chunk_size;
440 offset = 0;
441 cur_page = j;
442 }
443
444 return 0;
445}
Tvrtko Ursulin89d85892017-08-03 10:13:51 +0100446EXPORT_SYMBOL(__sg_alloc_table_from_pages);
447
448/**
449 * sg_alloc_table_from_pages - Allocate and initialize an sg table from
450 * an array of pages
451 * @sgt: The sg table header to use
452 * @pages: Pointer to an array of page pointers
453 * @n_pages: Number of pages in the pages array
454 * @offset: Offset from start of the first page to the start of a buffer
455 * @size: Number of valid bytes in the buffer (after offset)
456 * @gfp_mask: GFP allocation mask
457 *
458 * Description:
459 * Allocate and initialize an sg table from a list of pages. Contiguous
460 * ranges of the pages are squashed into a single scatterlist node. A user
461 * may provide an offset at a start and a size of valid data in a buffer
462 * specified by the page array. The returned sg table is released by
463 * sg_free_table.
464 *
465 * Returns:
466 * 0 on success, negative error on failure
467 */
468int sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages,
469 unsigned int n_pages, unsigned int offset,
470 unsigned long size, gfp_t gfp_mask)
471{
472 return __sg_alloc_table_from_pages(sgt, pages, n_pages, offset, size,
473 SCATTERLIST_MAX_SEGMENT, gfp_mask);
474}
Tomasz Stanislawskiefc42bc2012-06-18 09:25:01 +0200475EXPORT_SYMBOL(sg_alloc_table_from_pages);
476
Imre Deaka321e912013-02-27 17:02:56 -0800477void __sg_page_iter_start(struct sg_page_iter *piter,
478 struct scatterlist *sglist, unsigned int nents,
479 unsigned long pgoffset)
480{
481 piter->__pg_advance = 0;
482 piter->__nents = nents;
483
Imre Deaka321e912013-02-27 17:02:56 -0800484 piter->sg = sglist;
485 piter->sg_pgoffset = pgoffset;
486}
487EXPORT_SYMBOL(__sg_page_iter_start);
488
489static int sg_page_count(struct scatterlist *sg)
490{
491 return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT;
492}
493
494bool __sg_page_iter_next(struct sg_page_iter *piter)
495{
496 if (!piter->__nents || !piter->sg)
497 return false;
498
499 piter->sg_pgoffset += piter->__pg_advance;
500 piter->__pg_advance = 1;
501
502 while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {
503 piter->sg_pgoffset -= sg_page_count(piter->sg);
504 piter->sg = sg_next(piter->sg);
505 if (!--piter->__nents || !piter->sg)
506 return false;
507 }
Imre Deaka321e912013-02-27 17:02:56 -0800508
509 return true;
510}
511EXPORT_SYMBOL(__sg_page_iter_next);
512
Tomasz Stanislawskiefc42bc2012-06-18 09:25:01 +0200513/**
Tejun Heo137d3ed2008-07-19 23:03:35 +0900514 * sg_miter_start - start mapping iteration over a sg list
515 * @miter: sg mapping iter to be started
516 * @sgl: sg list to iterate over
517 * @nents: number of sg entries
518 *
519 * Description:
520 * Starts mapping iterator @miter.
521 *
522 * Context:
523 * Don't care.
524 */
525void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
526 unsigned int nents, unsigned int flags)
527{
528 memset(miter, 0, sizeof(struct sg_mapping_iter));
529
Imre Deak4225fc82013-02-27 17:02:57 -0800530 __sg_page_iter_start(&miter->piter, sgl, nents, 0);
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200531 WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG)));
Tejun Heo137d3ed2008-07-19 23:03:35 +0900532 miter->__flags = flags;
533}
534EXPORT_SYMBOL(sg_miter_start);
535
Akinobu Mita11052002013-07-08 16:01:52 -0700536static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)
537{
538 if (!miter->__remaining) {
539 struct scatterlist *sg;
540 unsigned long pgoffset;
541
542 if (!__sg_page_iter_next(&miter->piter))
543 return false;
544
545 sg = miter->piter.sg;
546 pgoffset = miter->piter.sg_pgoffset;
547
548 miter->__offset = pgoffset ? 0 : sg->offset;
549 miter->__remaining = sg->offset + sg->length -
550 (pgoffset << PAGE_SHIFT) - miter->__offset;
551 miter->__remaining = min_t(unsigned long, miter->__remaining,
552 PAGE_SIZE - miter->__offset);
553 }
554
555 return true;
556}
557
Tejun Heo137d3ed2008-07-19 23:03:35 +0900558/**
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700559 * sg_miter_skip - reposition mapping iterator
560 * @miter: sg mapping iter to be skipped
561 * @offset: number of bytes to plus the current location
562 *
563 * Description:
564 * Sets the offset of @miter to its current location plus @offset bytes.
565 * If mapping iterator @miter has been proceeded by sg_miter_next(), this
566 * stops @miter.
567 *
568 * Context:
569 * Don't care if @miter is stopped, or not proceeded yet.
570 * Otherwise, preemption disabled if the SG_MITER_ATOMIC is set.
571 *
572 * Returns:
573 * true if @miter contains the valid mapping. false if end of sg
574 * list is reached.
575 */
Ming Lei0d6077f2013-11-26 12:43:37 +0800576bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset)
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700577{
578 sg_miter_stop(miter);
579
580 while (offset) {
581 off_t consumed;
582
583 if (!sg_miter_get_next_page(miter))
584 return false;
585
586 consumed = min_t(off_t, offset, miter->__remaining);
587 miter->__offset += consumed;
588 miter->__remaining -= consumed;
589 offset -= consumed;
590 }
591
592 return true;
593}
Ming Lei0d6077f2013-11-26 12:43:37 +0800594EXPORT_SYMBOL(sg_miter_skip);
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700595
596/**
Tejun Heo137d3ed2008-07-19 23:03:35 +0900597 * sg_miter_next - proceed mapping iterator to the next mapping
598 * @miter: sg mapping iter to proceed
599 *
600 * Description:
Tejun Heo8290e2d2012-10-04 17:13:28 -0700601 * Proceeds @miter to the next mapping. @miter should have been started
602 * using sg_miter_start(). On successful return, @miter->page,
603 * @miter->addr and @miter->length point to the current mapping.
Tejun Heo137d3ed2008-07-19 23:03:35 +0900604 *
605 * Context:
Tejun Heo8290e2d2012-10-04 17:13:28 -0700606 * Preemption disabled if SG_MITER_ATOMIC. Preemption must stay disabled
607 * till @miter is stopped. May sleep if !SG_MITER_ATOMIC.
Tejun Heo137d3ed2008-07-19 23:03:35 +0900608 *
609 * Returns:
610 * true if @miter contains the next mapping. false if end of sg
611 * list is reached.
612 */
613bool sg_miter_next(struct sg_mapping_iter *miter)
614{
Tejun Heo137d3ed2008-07-19 23:03:35 +0900615 sg_miter_stop(miter);
616
Imre Deak4225fc82013-02-27 17:02:57 -0800617 /*
618 * Get to the next page if necessary.
619 * __remaining, __offset is adjusted by sg_miter_stop
620 */
Akinobu Mita11052002013-07-08 16:01:52 -0700621 if (!sg_miter_get_next_page(miter))
622 return false;
Imre Deak4225fc82013-02-27 17:02:57 -0800623
Imre Deak2db76d72013-03-26 15:14:18 +0200624 miter->page = sg_page_iter_page(&miter->piter);
Imre Deak4225fc82013-02-27 17:02:57 -0800625 miter->consumed = miter->length = miter->__remaining;
Tejun Heo137d3ed2008-07-19 23:03:35 +0900626
627 if (miter->__flags & SG_MITER_ATOMIC)
Imre Deak4225fc82013-02-27 17:02:57 -0800628 miter->addr = kmap_atomic(miter->page) + miter->__offset;
Tejun Heo137d3ed2008-07-19 23:03:35 +0900629 else
Imre Deak4225fc82013-02-27 17:02:57 -0800630 miter->addr = kmap(miter->page) + miter->__offset;
Tejun Heo137d3ed2008-07-19 23:03:35 +0900631
632 return true;
633}
634EXPORT_SYMBOL(sg_miter_next);
635
636/**
637 * sg_miter_stop - stop mapping iteration
638 * @miter: sg mapping iter to be stopped
639 *
640 * Description:
641 * Stops mapping iterator @miter. @miter should have been started
Masahiro Yamada4ba6a2b2016-02-08 16:09:08 +0900642 * using sg_miter_start(). A stopped iteration can be resumed by
643 * calling sg_miter_next() on it. This is useful when resources (kmap)
644 * need to be released during iteration.
Tejun Heo137d3ed2008-07-19 23:03:35 +0900645 *
646 * Context:
Tejun Heo8290e2d2012-10-04 17:13:28 -0700647 * Preemption disabled if the SG_MITER_ATOMIC is set. Don't care
648 * otherwise.
Tejun Heo137d3ed2008-07-19 23:03:35 +0900649 */
650void sg_miter_stop(struct sg_mapping_iter *miter)
651{
652 WARN_ON(miter->consumed > miter->length);
653
654 /* drop resources from the last iteration */
655 if (miter->addr) {
656 miter->__offset += miter->consumed;
Imre Deak4225fc82013-02-27 17:02:57 -0800657 miter->__remaining -= miter->consumed;
Tejun Heo137d3ed2008-07-19 23:03:35 +0900658
Ming Lei3d77b502013-10-31 16:34:17 -0700659 if ((miter->__flags & SG_MITER_TO_SG) &&
660 !PageSlab(miter->page))
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200661 flush_kernel_dcache_page(miter->page);
662
Tejun Heo137d3ed2008-07-19 23:03:35 +0900663 if (miter->__flags & SG_MITER_ATOMIC) {
Tejun Heo8290e2d2012-10-04 17:13:28 -0700664 WARN_ON_ONCE(preemptible());
Cong Wangc3eede82011-11-25 23:14:39 +0800665 kunmap_atomic(miter->addr);
Tejun Heo137d3ed2008-07-19 23:03:35 +0900666 } else
Arjan van de Venf652c522008-11-19 15:36:19 -0800667 kunmap(miter->page);
Tejun Heo137d3ed2008-07-19 23:03:35 +0900668
669 miter->page = NULL;
670 miter->addr = NULL;
671 miter->length = 0;
672 miter->consumed = 0;
673 }
674}
675EXPORT_SYMBOL(sg_miter_stop);
676
677/**
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900678 * sg_copy_buffer - Copy data between a linear buffer and an SG list
679 * @sgl: The SG list
680 * @nents: Number of SG entries
681 * @buf: Where to copy from
682 * @buflen: The number of bytes to copy
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700683 * @skip: Number of bytes to skip before copying
684 * @to_buffer: transfer direction (true == from an sg list to a
685 * buffer, false == from a buffer to an sg list
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900686 *
687 * Returns the number of copied bytes.
688 *
689 **/
Dave Gordon386ecb12015-06-30 14:58:57 -0700690size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
691 size_t buflen, off_t skip, bool to_buffer)
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900692{
Tejun Heo137d3ed2008-07-19 23:03:35 +0900693 unsigned int offset = 0;
694 struct sg_mapping_iter miter;
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200695 unsigned int sg_flags = SG_MITER_ATOMIC;
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900696
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200697 if (to_buffer)
698 sg_flags |= SG_MITER_FROM_SG;
699 else
700 sg_flags |= SG_MITER_TO_SG;
701
702 sg_miter_start(&miter, sgl, nents, sg_flags);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900703
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700704 if (!sg_miter_skip(&miter, skip))
705 return false;
706
Gilad Ben-Yossef1d5210e2017-02-27 14:28:27 -0800707 while ((offset < buflen) && sg_miter_next(&miter)) {
Tejun Heo137d3ed2008-07-19 23:03:35 +0900708 unsigned int len;
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900709
Tejun Heo137d3ed2008-07-19 23:03:35 +0900710 len = min(miter.length, buflen - offset);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900711
Tejun Heo137d3ed2008-07-19 23:03:35 +0900712 if (to_buffer)
713 memcpy(buf + offset, miter.addr, len);
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200714 else
Tejun Heo137d3ed2008-07-19 23:03:35 +0900715 memcpy(miter.addr, buf + offset, len);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900716
Tejun Heo137d3ed2008-07-19 23:03:35 +0900717 offset += len;
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900718 }
719
Tejun Heo137d3ed2008-07-19 23:03:35 +0900720 sg_miter_stop(&miter);
721
722 return offset;
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900723}
Dave Gordon386ecb12015-06-30 14:58:57 -0700724EXPORT_SYMBOL(sg_copy_buffer);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900725
726/**
727 * sg_copy_from_buffer - Copy from a linear buffer to an SG list
728 * @sgl: The SG list
729 * @nents: Number of SG entries
730 * @buf: Where to copy from
731 * @buflen: The number of bytes to copy
732 *
733 * Returns the number of copied bytes.
734 *
735 **/
736size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
Dave Gordon2a1bf8f2015-06-30 14:58:54 -0700737 const void *buf, size_t buflen)
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900738{
Dave Gordon2a1bf8f2015-06-30 14:58:54 -0700739 return sg_copy_buffer(sgl, nents, (void *)buf, buflen, 0, false);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900740}
741EXPORT_SYMBOL(sg_copy_from_buffer);
742
743/**
744 * sg_copy_to_buffer - Copy from an SG list to a linear buffer
745 * @sgl: The SG list
746 * @nents: Number of SG entries
747 * @buf: Where to copy to
748 * @buflen: The number of bytes to copy
749 *
750 * Returns the number of copied bytes.
751 *
752 **/
753size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
754 void *buf, size_t buflen)
755{
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700756 return sg_copy_buffer(sgl, nents, buf, buflen, 0, true);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900757}
758EXPORT_SYMBOL(sg_copy_to_buffer);
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700759
760/**
761 * sg_pcopy_from_buffer - Copy from a linear buffer to an SG list
762 * @sgl: The SG list
763 * @nents: Number of SG entries
764 * @buf: Where to copy from
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700765 * @buflen: The number of bytes to copy
Dave Gordon4dc7daf2015-06-30 14:58:52 -0700766 * @skip: Number of bytes to skip before copying
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700767 *
768 * Returns the number of copied bytes.
769 *
770 **/
771size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
Dave Gordon2a1bf8f2015-06-30 14:58:54 -0700772 const void *buf, size_t buflen, off_t skip)
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700773{
Dave Gordon2a1bf8f2015-06-30 14:58:54 -0700774 return sg_copy_buffer(sgl, nents, (void *)buf, buflen, skip, false);
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700775}
776EXPORT_SYMBOL(sg_pcopy_from_buffer);
777
778/**
779 * sg_pcopy_to_buffer - Copy from an SG list to a linear buffer
780 * @sgl: The SG list
781 * @nents: Number of SG entries
782 * @buf: Where to copy to
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700783 * @buflen: The number of bytes to copy
Dave Gordon4dc7daf2015-06-30 14:58:52 -0700784 * @skip: Number of bytes to skip before copying
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700785 *
786 * Returns the number of copied bytes.
787 *
788 **/
789size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
790 void *buf, size_t buflen, off_t skip)
791{
792 return sg_copy_buffer(sgl, nents, buf, buflen, skip, true);
793}
794EXPORT_SYMBOL(sg_pcopy_to_buffer);
Johannes Thumshirn0945e562017-06-07 11:45:28 +0200795
796/**
797 * sg_zero_buffer - Zero-out a part of a SG list
798 * @sgl: The SG list
799 * @nents: Number of SG entries
800 * @buflen: The number of bytes to zero out
801 * @skip: Number of bytes to skip before zeroing
802 *
803 * Returns the number of bytes zeroed.
804 **/
805size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents,
806 size_t buflen, off_t skip)
807{
808 unsigned int offset = 0;
809 struct sg_mapping_iter miter;
810 unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG;
811
812 sg_miter_start(&miter, sgl, nents, sg_flags);
813
814 if (!sg_miter_skip(&miter, skip))
815 return false;
816
817 while (offset < buflen && sg_miter_next(&miter)) {
818 unsigned int len;
819
820 len = min(miter.length, buflen - offset);
821 memset(miter.addr, 0, len);
822
823 offset += len;
824 }
825
826 sg_miter_stop(&miter);
827 return offset;
828}
829EXPORT_SYMBOL(sg_zero_buffer);