blob: 53728d391d3a70f15d0f42499d92cd87b670b962 [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
Bart Van Asschee80a0af2018-01-05 08:26:46 -0800477#ifdef CONFIG_SGL_ALLOC
478
479/**
480 * sgl_alloc_order - allocate a scatterlist and its pages
481 * @length: Length in bytes of the scatterlist. Must be at least one
482 * @order: Second argument for alloc_pages()
483 * @chainable: Whether or not to allocate an extra element in the scatterlist
484 * for scatterlist chaining purposes
485 * @gfp: Memory allocation flags
486 * @nent_p: [out] Number of entries in the scatterlist that have pages
487 *
488 * Returns: A pointer to an initialized scatterlist or %NULL upon failure.
489 */
490struct scatterlist *sgl_alloc_order(unsigned long long length,
491 unsigned int order, bool chainable,
492 gfp_t gfp, unsigned int *nent_p)
493{
494 struct scatterlist *sgl, *sg;
495 struct page *page;
496 unsigned int nent, nalloc;
497 u32 elem_len;
498
499 nent = round_up(length, PAGE_SIZE << order) >> (PAGE_SHIFT + order);
500 /* Check for integer overflow */
501 if (length > (nent << (PAGE_SHIFT + order)))
502 return NULL;
503 nalloc = nent;
504 if (chainable) {
505 /* Check for integer overflow */
506 if (nalloc + 1 < nalloc)
507 return NULL;
508 nalloc++;
509 }
510 sgl = kmalloc_array(nalloc, sizeof(struct scatterlist),
511 (gfp & ~GFP_DMA) | __GFP_ZERO);
512 if (!sgl)
513 return NULL;
514
Bart Van Assche8c7a8d12018-01-19 11:00:54 -0800515 sg_init_table(sgl, nalloc);
Bart Van Asschee80a0af2018-01-05 08:26:46 -0800516 sg = sgl;
517 while (length) {
518 elem_len = min_t(u64, length, PAGE_SIZE << order);
519 page = alloc_pages(gfp, order);
520 if (!page) {
521 sgl_free(sgl);
522 return NULL;
523 }
524
525 sg_set_page(sg, page, elem_len, 0);
526 length -= elem_len;
527 sg = sg_next(sg);
528 }
Bart Van Assche8c7a8d12018-01-19 11:00:54 -0800529 WARN_ONCE(length, "length = %lld\n", length);
Bart Van Asschee80a0af2018-01-05 08:26:46 -0800530 if (nent_p)
531 *nent_p = nent;
532 return sgl;
533}
534EXPORT_SYMBOL(sgl_alloc_order);
535
536/**
537 * sgl_alloc - allocate a scatterlist and its pages
538 * @length: Length in bytes of the scatterlist
539 * @gfp: Memory allocation flags
540 * @nent_p: [out] Number of entries in the scatterlist
541 *
542 * Returns: A pointer to an initialized scatterlist or %NULL upon failure.
543 */
544struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp,
545 unsigned int *nent_p)
546{
547 return sgl_alloc_order(length, 0, false, gfp, nent_p);
548}
549EXPORT_SYMBOL(sgl_alloc);
550
551/**
Bart Van Assche8c7a8d12018-01-19 11:00:54 -0800552 * sgl_free_n_order - free a scatterlist and its pages
553 * @sgl: Scatterlist with one or more elements
554 * @nents: Maximum number of elements to free
555 * @order: Second argument for __free_pages()
556 *
557 * Notes:
558 * - If several scatterlists have been chained and each chain element is
559 * freed separately then it's essential to set nents correctly to avoid that a
560 * page would get freed twice.
561 * - All pages in a chained scatterlist can be freed at once by setting @nents
562 * to a high number.
563 */
564void sgl_free_n_order(struct scatterlist *sgl, int nents, int order)
565{
566 struct scatterlist *sg;
567 struct page *page;
568 int i;
569
570 for_each_sg(sgl, sg, nents, i) {
571 if (!sg)
572 break;
573 page = sg_page(sg);
574 if (page)
575 __free_pages(page, order);
576 }
577 kfree(sgl);
578}
579EXPORT_SYMBOL(sgl_free_n_order);
580
581/**
Bart Van Asschee80a0af2018-01-05 08:26:46 -0800582 * sgl_free_order - free a scatterlist and its pages
583 * @sgl: Scatterlist with one or more elements
584 * @order: Second argument for __free_pages()
585 */
586void sgl_free_order(struct scatterlist *sgl, int order)
587{
Bart Van Assche8c7a8d12018-01-19 11:00:54 -0800588 sgl_free_n_order(sgl, INT_MAX, order);
Bart Van Asschee80a0af2018-01-05 08:26:46 -0800589}
590EXPORT_SYMBOL(sgl_free_order);
591
592/**
593 * sgl_free - free a scatterlist and its pages
594 * @sgl: Scatterlist with one or more elements
595 */
596void sgl_free(struct scatterlist *sgl)
597{
598 sgl_free_order(sgl, 0);
599}
600EXPORT_SYMBOL(sgl_free);
601
602#endif /* CONFIG_SGL_ALLOC */
603
Imre Deaka321e912013-02-27 17:02:56 -0800604void __sg_page_iter_start(struct sg_page_iter *piter,
605 struct scatterlist *sglist, unsigned int nents,
606 unsigned long pgoffset)
607{
608 piter->__pg_advance = 0;
609 piter->__nents = nents;
610
Imre Deaka321e912013-02-27 17:02:56 -0800611 piter->sg = sglist;
612 piter->sg_pgoffset = pgoffset;
613}
614EXPORT_SYMBOL(__sg_page_iter_start);
615
616static int sg_page_count(struct scatterlist *sg)
617{
618 return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT;
619}
620
621bool __sg_page_iter_next(struct sg_page_iter *piter)
622{
623 if (!piter->__nents || !piter->sg)
624 return false;
625
626 piter->sg_pgoffset += piter->__pg_advance;
627 piter->__pg_advance = 1;
628
629 while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {
630 piter->sg_pgoffset -= sg_page_count(piter->sg);
631 piter->sg = sg_next(piter->sg);
632 if (!--piter->__nents || !piter->sg)
633 return false;
634 }
Imre Deaka321e912013-02-27 17:02:56 -0800635
636 return true;
637}
638EXPORT_SYMBOL(__sg_page_iter_next);
639
Tomasz Stanislawskiefc42bc2012-06-18 09:25:01 +0200640/**
Tejun Heo137d3ed2008-07-19 23:03:35 +0900641 * sg_miter_start - start mapping iteration over a sg list
642 * @miter: sg mapping iter to be started
643 * @sgl: sg list to iterate over
644 * @nents: number of sg entries
645 *
646 * Description:
647 * Starts mapping iterator @miter.
648 *
649 * Context:
650 * Don't care.
651 */
652void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
653 unsigned int nents, unsigned int flags)
654{
655 memset(miter, 0, sizeof(struct sg_mapping_iter));
656
Imre Deak4225fc82013-02-27 17:02:57 -0800657 __sg_page_iter_start(&miter->piter, sgl, nents, 0);
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200658 WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG)));
Tejun Heo137d3ed2008-07-19 23:03:35 +0900659 miter->__flags = flags;
660}
661EXPORT_SYMBOL(sg_miter_start);
662
Akinobu Mita11052002013-07-08 16:01:52 -0700663static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)
664{
665 if (!miter->__remaining) {
666 struct scatterlist *sg;
667 unsigned long pgoffset;
668
669 if (!__sg_page_iter_next(&miter->piter))
670 return false;
671
672 sg = miter->piter.sg;
673 pgoffset = miter->piter.sg_pgoffset;
674
675 miter->__offset = pgoffset ? 0 : sg->offset;
676 miter->__remaining = sg->offset + sg->length -
677 (pgoffset << PAGE_SHIFT) - miter->__offset;
678 miter->__remaining = min_t(unsigned long, miter->__remaining,
679 PAGE_SIZE - miter->__offset);
680 }
681
682 return true;
683}
684
Tejun Heo137d3ed2008-07-19 23:03:35 +0900685/**
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700686 * sg_miter_skip - reposition mapping iterator
687 * @miter: sg mapping iter to be skipped
688 * @offset: number of bytes to plus the current location
689 *
690 * Description:
691 * Sets the offset of @miter to its current location plus @offset bytes.
692 * If mapping iterator @miter has been proceeded by sg_miter_next(), this
693 * stops @miter.
694 *
695 * Context:
696 * Don't care if @miter is stopped, or not proceeded yet.
697 * Otherwise, preemption disabled if the SG_MITER_ATOMIC is set.
698 *
699 * Returns:
700 * true if @miter contains the valid mapping. false if end of sg
701 * list is reached.
702 */
Ming Lei0d6077f2013-11-26 12:43:37 +0800703bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset)
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700704{
705 sg_miter_stop(miter);
706
707 while (offset) {
708 off_t consumed;
709
710 if (!sg_miter_get_next_page(miter))
711 return false;
712
713 consumed = min_t(off_t, offset, miter->__remaining);
714 miter->__offset += consumed;
715 miter->__remaining -= consumed;
716 offset -= consumed;
717 }
718
719 return true;
720}
Ming Lei0d6077f2013-11-26 12:43:37 +0800721EXPORT_SYMBOL(sg_miter_skip);
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700722
723/**
Tejun Heo137d3ed2008-07-19 23:03:35 +0900724 * sg_miter_next - proceed mapping iterator to the next mapping
725 * @miter: sg mapping iter to proceed
726 *
727 * Description:
Tejun Heo8290e2d2012-10-04 17:13:28 -0700728 * Proceeds @miter to the next mapping. @miter should have been started
729 * using sg_miter_start(). On successful return, @miter->page,
730 * @miter->addr and @miter->length point to the current mapping.
Tejun Heo137d3ed2008-07-19 23:03:35 +0900731 *
732 * Context:
Tejun Heo8290e2d2012-10-04 17:13:28 -0700733 * Preemption disabled if SG_MITER_ATOMIC. Preemption must stay disabled
734 * till @miter is stopped. May sleep if !SG_MITER_ATOMIC.
Tejun Heo137d3ed2008-07-19 23:03:35 +0900735 *
736 * Returns:
737 * true if @miter contains the next mapping. false if end of sg
738 * list is reached.
739 */
740bool sg_miter_next(struct sg_mapping_iter *miter)
741{
Tejun Heo137d3ed2008-07-19 23:03:35 +0900742 sg_miter_stop(miter);
743
Imre Deak4225fc82013-02-27 17:02:57 -0800744 /*
745 * Get to the next page if necessary.
746 * __remaining, __offset is adjusted by sg_miter_stop
747 */
Akinobu Mita11052002013-07-08 16:01:52 -0700748 if (!sg_miter_get_next_page(miter))
749 return false;
Imre Deak4225fc82013-02-27 17:02:57 -0800750
Imre Deak2db76d72013-03-26 15:14:18 +0200751 miter->page = sg_page_iter_page(&miter->piter);
Imre Deak4225fc82013-02-27 17:02:57 -0800752 miter->consumed = miter->length = miter->__remaining;
Tejun Heo137d3ed2008-07-19 23:03:35 +0900753
754 if (miter->__flags & SG_MITER_ATOMIC)
Imre Deak4225fc82013-02-27 17:02:57 -0800755 miter->addr = kmap_atomic(miter->page) + miter->__offset;
Tejun Heo137d3ed2008-07-19 23:03:35 +0900756 else
Imre Deak4225fc82013-02-27 17:02:57 -0800757 miter->addr = kmap(miter->page) + miter->__offset;
Tejun Heo137d3ed2008-07-19 23:03:35 +0900758
759 return true;
760}
761EXPORT_SYMBOL(sg_miter_next);
762
763/**
764 * sg_miter_stop - stop mapping iteration
765 * @miter: sg mapping iter to be stopped
766 *
767 * Description:
768 * Stops mapping iterator @miter. @miter should have been started
Masahiro Yamada4ba6a2b2016-02-08 16:09:08 +0900769 * using sg_miter_start(). A stopped iteration can be resumed by
770 * calling sg_miter_next() on it. This is useful when resources (kmap)
771 * need to be released during iteration.
Tejun Heo137d3ed2008-07-19 23:03:35 +0900772 *
773 * Context:
Tejun Heo8290e2d2012-10-04 17:13:28 -0700774 * Preemption disabled if the SG_MITER_ATOMIC is set. Don't care
775 * otherwise.
Tejun Heo137d3ed2008-07-19 23:03:35 +0900776 */
777void sg_miter_stop(struct sg_mapping_iter *miter)
778{
779 WARN_ON(miter->consumed > miter->length);
780
781 /* drop resources from the last iteration */
782 if (miter->addr) {
783 miter->__offset += miter->consumed;
Imre Deak4225fc82013-02-27 17:02:57 -0800784 miter->__remaining -= miter->consumed;
Tejun Heo137d3ed2008-07-19 23:03:35 +0900785
Ming Lei3d77b502013-10-31 16:34:17 -0700786 if ((miter->__flags & SG_MITER_TO_SG) &&
787 !PageSlab(miter->page))
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200788 flush_kernel_dcache_page(miter->page);
789
Tejun Heo137d3ed2008-07-19 23:03:35 +0900790 if (miter->__flags & SG_MITER_ATOMIC) {
Tejun Heo8290e2d2012-10-04 17:13:28 -0700791 WARN_ON_ONCE(preemptible());
Cong Wangc3eede82011-11-25 23:14:39 +0800792 kunmap_atomic(miter->addr);
Tejun Heo137d3ed2008-07-19 23:03:35 +0900793 } else
Arjan van de Venf652c522008-11-19 15:36:19 -0800794 kunmap(miter->page);
Tejun Heo137d3ed2008-07-19 23:03:35 +0900795
796 miter->page = NULL;
797 miter->addr = NULL;
798 miter->length = 0;
799 miter->consumed = 0;
800 }
801}
802EXPORT_SYMBOL(sg_miter_stop);
803
804/**
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900805 * sg_copy_buffer - Copy data between a linear buffer and an SG list
806 * @sgl: The SG list
807 * @nents: Number of SG entries
808 * @buf: Where to copy from
809 * @buflen: The number of bytes to copy
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700810 * @skip: Number of bytes to skip before copying
811 * @to_buffer: transfer direction (true == from an sg list to a
812 * buffer, false == from a buffer to an sg list
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900813 *
814 * Returns the number of copied bytes.
815 *
816 **/
Dave Gordon386ecb12015-06-30 14:58:57 -0700817size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
818 size_t buflen, off_t skip, bool to_buffer)
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900819{
Tejun Heo137d3ed2008-07-19 23:03:35 +0900820 unsigned int offset = 0;
821 struct sg_mapping_iter miter;
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200822 unsigned int sg_flags = SG_MITER_ATOMIC;
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900823
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200824 if (to_buffer)
825 sg_flags |= SG_MITER_FROM_SG;
826 else
827 sg_flags |= SG_MITER_TO_SG;
828
829 sg_miter_start(&miter, sgl, nents, sg_flags);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900830
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700831 if (!sg_miter_skip(&miter, skip))
832 return false;
833
Gilad Ben-Yossef1d5210ef2017-02-27 14:28:27 -0800834 while ((offset < buflen) && sg_miter_next(&miter)) {
Tejun Heo137d3ed2008-07-19 23:03:35 +0900835 unsigned int len;
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900836
Tejun Heo137d3ed2008-07-19 23:03:35 +0900837 len = min(miter.length, buflen - offset);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900838
Tejun Heo137d3ed2008-07-19 23:03:35 +0900839 if (to_buffer)
840 memcpy(buf + offset, miter.addr, len);
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200841 else
Tejun Heo137d3ed2008-07-19 23:03:35 +0900842 memcpy(miter.addr, buf + offset, len);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900843
Tejun Heo137d3ed2008-07-19 23:03:35 +0900844 offset += len;
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900845 }
846
Tejun Heo137d3ed2008-07-19 23:03:35 +0900847 sg_miter_stop(&miter);
848
849 return offset;
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900850}
Dave Gordon386ecb12015-06-30 14:58:57 -0700851EXPORT_SYMBOL(sg_copy_buffer);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900852
853/**
854 * sg_copy_from_buffer - Copy from a linear buffer to an SG list
855 * @sgl: The SG list
856 * @nents: Number of SG entries
857 * @buf: Where to copy from
858 * @buflen: The number of bytes to copy
859 *
860 * Returns the number of copied bytes.
861 *
862 **/
863size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
Dave Gordon2a1bf8f2015-06-30 14:58:54 -0700864 const void *buf, size_t buflen)
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900865{
Dave Gordon2a1bf8f2015-06-30 14:58:54 -0700866 return sg_copy_buffer(sgl, nents, (void *)buf, buflen, 0, false);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900867}
868EXPORT_SYMBOL(sg_copy_from_buffer);
869
870/**
871 * sg_copy_to_buffer - Copy from an SG list to a linear buffer
872 * @sgl: The SG list
873 * @nents: Number of SG entries
874 * @buf: Where to copy to
875 * @buflen: The number of bytes to copy
876 *
877 * Returns the number of copied bytes.
878 *
879 **/
880size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
881 void *buf, size_t buflen)
882{
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700883 return sg_copy_buffer(sgl, nents, buf, buflen, 0, true);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900884}
885EXPORT_SYMBOL(sg_copy_to_buffer);
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700886
887/**
888 * sg_pcopy_from_buffer - Copy from a linear buffer to an SG list
889 * @sgl: The SG list
890 * @nents: Number of SG entries
891 * @buf: Where to copy from
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700892 * @buflen: The number of bytes to copy
Dave Gordon4dc7daf2015-06-30 14:58:52 -0700893 * @skip: Number of bytes to skip before copying
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700894 *
895 * Returns the number of copied bytes.
896 *
897 **/
898size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
Dave Gordon2a1bf8f2015-06-30 14:58:54 -0700899 const void *buf, size_t buflen, off_t skip)
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700900{
Dave Gordon2a1bf8f2015-06-30 14:58:54 -0700901 return sg_copy_buffer(sgl, nents, (void *)buf, buflen, skip, false);
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700902}
903EXPORT_SYMBOL(sg_pcopy_from_buffer);
904
905/**
906 * sg_pcopy_to_buffer - Copy from an SG list to a linear buffer
907 * @sgl: The SG list
908 * @nents: Number of SG entries
909 * @buf: Where to copy to
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700910 * @buflen: The number of bytes to copy
Dave Gordon4dc7daf2015-06-30 14:58:52 -0700911 * @skip: Number of bytes to skip before copying
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700912 *
913 * Returns the number of copied bytes.
914 *
915 **/
916size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
917 void *buf, size_t buflen, off_t skip)
918{
919 return sg_copy_buffer(sgl, nents, buf, buflen, skip, true);
920}
921EXPORT_SYMBOL(sg_pcopy_to_buffer);
Johannes Thumshirn0945e562017-06-07 11:45:28 +0200922
923/**
924 * sg_zero_buffer - Zero-out a part of a SG list
925 * @sgl: The SG list
926 * @nents: Number of SG entries
927 * @buflen: The number of bytes to zero out
928 * @skip: Number of bytes to skip before zeroing
929 *
930 * Returns the number of bytes zeroed.
931 **/
932size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents,
933 size_t buflen, off_t skip)
934{
935 unsigned int offset = 0;
936 struct sg_mapping_iter miter;
937 unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG;
938
939 sg_miter_start(&miter, sgl, nents, sg_flags);
940
941 if (!sg_miter_skip(&miter, skip))
942 return false;
943
944 while (offset < buflen && sg_miter_next(&miter)) {
945 unsigned int len;
946
947 len = min(miter.length, buflen - offset);
948 memset(miter.addr, 0, len);
949
950 offset += len;
951 }
952
953 sg_miter_stop(&miter);
954 return offset;
955}
956EXPORT_SYMBOL(sg_zero_buffer);