blob: c9f2e8c6ccc996c8a40bac6872749185170ec7f9 [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
59
60/**
Jens Axboe0db92992007-11-30 09:16:50 +010061 * sg_last - return the last scatterlist entry in a list
62 * @sgl: First entry in the scatterlist
63 * @nents: Number of entries in the scatterlist
64 *
65 * Description:
66 * Should only be used casually, it (currently) scans the entire list
67 * to get the last entry.
68 *
69 * Note that the @sgl@ pointer passed in need not be the first one,
70 * the important bit is that @nents@ denotes the number of entries that
71 * exist from @sgl@.
72 *
73 **/
74struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents)
75{
Laura Abbott308c09f2014-08-08 14:23:25 -070076#ifndef CONFIG_ARCH_HAS_SG_CHAIN
Jens Axboe0db92992007-11-30 09:16:50 +010077 struct scatterlist *ret = &sgl[nents - 1];
78#else
79 struct scatterlist *sg, *ret = NULL;
80 unsigned int i;
81
82 for_each_sg(sgl, sg, nents, i)
83 ret = sg;
84
85#endif
86#ifdef CONFIG_DEBUG_SG
87 BUG_ON(sgl[0].sg_magic != SG_MAGIC);
88 BUG_ON(!sg_is_last(ret));
89#endif
90 return ret;
91}
92EXPORT_SYMBOL(sg_last);
93
94/**
95 * sg_init_table - Initialize SG table
96 * @sgl: The SG table
97 * @nents: Number of entries in table
98 *
99 * Notes:
100 * If this is part of a chained sg table, sg_mark_end() should be
101 * used only on the last table part.
102 *
103 **/
104void sg_init_table(struct scatterlist *sgl, unsigned int nents)
105{
106 memset(sgl, 0, sizeof(*sgl) * nents);
107#ifdef CONFIG_DEBUG_SG
108 {
109 unsigned int i;
110 for (i = 0; i < nents; i++)
111 sgl[i].sg_magic = SG_MAGIC;
112 }
113#endif
114 sg_mark_end(&sgl[nents - 1]);
115}
116EXPORT_SYMBOL(sg_init_table);
117
118/**
119 * sg_init_one - Initialize a single entry sg list
120 * @sg: SG entry
121 * @buf: Virtual address for IO
122 * @buflen: IO length
123 *
124 **/
125void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen)
126{
127 sg_init_table(sg, 1);
128 sg_set_buf(sg, buf, buflen);
129}
130EXPORT_SYMBOL(sg_init_one);
131
132/*
133 * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree
134 * helpers.
135 */
136static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
137{
Chris Wilsonb94de9b2010-07-28 22:59:02 +0100138 if (nents == SG_MAX_SINGLE_ALLOC) {
139 /*
140 * Kmemleak doesn't track page allocations as they are not
141 * commonly used (in a raw form) for kernel data structures.
142 * As we chain together a list of pages and then a normal
143 * kmalloc (tracked by kmemleak), in order to for that last
144 * allocation not to become decoupled (and thus a
145 * false-positive) we need to inform kmemleak of all the
146 * intermediate allocations.
147 */
148 void *ptr = (void *) __get_free_page(gfp_mask);
149 kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask);
150 return ptr;
151 } else
Jens Axboe0db92992007-11-30 09:16:50 +0100152 return kmalloc(nents * sizeof(struct scatterlist), gfp_mask);
153}
154
155static void sg_kfree(struct scatterlist *sg, unsigned int nents)
156{
Chris Wilsonb94de9b2010-07-28 22:59:02 +0100157 if (nents == SG_MAX_SINGLE_ALLOC) {
158 kmemleak_free(sg);
Jens Axboe0db92992007-11-30 09:16:50 +0100159 free_page((unsigned long) sg);
Chris Wilsonb94de9b2010-07-28 22:59:02 +0100160 } else
Jens Axboe0db92992007-11-30 09:16:50 +0100161 kfree(sg);
162}
163
164/**
165 * __sg_free_table - Free a previously mapped sg table
166 * @table: The sg table header to use
James Bottomley7cedb1f2008-01-13 14:15:28 -0600167 * @max_ents: The maximum number of entries per single scatterlist
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200168 * @skip_first_chunk: don't free the (preallocated) first scatterlist chunk
Jens Axboe0db92992007-11-30 09:16:50 +0100169 * @free_fn: Free function
170 *
171 * Description:
James Bottomley7cedb1f2008-01-13 14:15:28 -0600172 * Free an sg table previously allocated and setup with
173 * __sg_alloc_table(). The @max_ents value must be identical to
174 * that previously used with __sg_alloc_table().
Jens Axboe0db92992007-11-30 09:16:50 +0100175 *
176 **/
James Bottomley7cedb1f2008-01-13 14:15:28 -0600177void __sg_free_table(struct sg_table *table, unsigned int max_ents,
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200178 bool skip_first_chunk, sg_free_fn *free_fn)
Jens Axboe0db92992007-11-30 09:16:50 +0100179{
180 struct scatterlist *sgl, *next;
181
182 if (unlikely(!table->sgl))
183 return;
184
185 sgl = table->sgl;
186 while (table->orig_nents) {
187 unsigned int alloc_size = table->orig_nents;
188 unsigned int sg_size;
189
190 /*
James Bottomley7cedb1f2008-01-13 14:15:28 -0600191 * If we have more than max_ents segments left,
Jens Axboe0db92992007-11-30 09:16:50 +0100192 * then assign 'next' to the sg table after the current one.
193 * sg_size is then one less than alloc size, since the last
194 * element is the chain pointer.
195 */
James Bottomley7cedb1f2008-01-13 14:15:28 -0600196 if (alloc_size > max_ents) {
197 next = sg_chain_ptr(&sgl[max_ents - 1]);
198 alloc_size = max_ents;
Jens Axboe0db92992007-11-30 09:16:50 +0100199 sg_size = alloc_size - 1;
200 } else {
201 sg_size = alloc_size;
202 next = NULL;
203 }
204
205 table->orig_nents -= sg_size;
Tony Battersbyc21e59d2014-10-23 15:10:21 -0400206 if (skip_first_chunk)
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200207 skip_first_chunk = false;
Tony Battersbyc21e59d2014-10-23 15:10:21 -0400208 else
209 free_fn(sgl, alloc_size);
Jens Axboe0db92992007-11-30 09:16:50 +0100210 sgl = next;
211 }
212
213 table->sgl = NULL;
214}
215EXPORT_SYMBOL(__sg_free_table);
216
217/**
218 * sg_free_table - Free a previously allocated sg table
219 * @table: The mapped sg table header
220 *
221 **/
222void sg_free_table(struct sg_table *table)
223{
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200224 __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);
Jens Axboe0db92992007-11-30 09:16:50 +0100225}
226EXPORT_SYMBOL(sg_free_table);
227
228/**
229 * __sg_alloc_table - Allocate and initialize an sg table with given allocator
230 * @table: The sg table header to use
231 * @nents: Number of entries in sg list
James Bottomley7cedb1f2008-01-13 14:15:28 -0600232 * @max_ents: The maximum number of entries the allocator returns per call
Jens Axboe0db92992007-11-30 09:16:50 +0100233 * @gfp_mask: GFP allocation mask
234 * @alloc_fn: Allocator to use
235 *
James Bottomley7cedb1f2008-01-13 14:15:28 -0600236 * Description:
237 * This function returns a @table @nents long. The allocator is
238 * defined to return scatterlist chunks of maximum size @max_ents.
239 * Thus if @nents is bigger than @max_ents, the scatterlists will be
240 * chained in units of @max_ents.
241 *
Jens Axboe0db92992007-11-30 09:16:50 +0100242 * Notes:
243 * If this function returns non-0 (eg failure), the caller must call
244 * __sg_free_table() to cleanup any leftover allocations.
245 *
246 **/
James Bottomley7cedb1f2008-01-13 14:15:28 -0600247int __sg_alloc_table(struct sg_table *table, unsigned int nents,
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200248 unsigned int max_ents, struct scatterlist *first_chunk,
249 gfp_t gfp_mask, sg_alloc_fn *alloc_fn)
Jens Axboe0db92992007-11-30 09:16:50 +0100250{
251 struct scatterlist *sg, *prv;
252 unsigned int left;
253
Dan Carpenter27daabd2013-07-08 16:01:58 -0700254 memset(table, 0, sizeof(*table));
255
256 if (nents == 0)
257 return -EINVAL;
Laura Abbott308c09f2014-08-08 14:23:25 -0700258#ifndef CONFIG_ARCH_HAS_SG_CHAIN
Nick Bowler6fd59a82012-12-17 16:05:20 -0800259 if (WARN_ON_ONCE(nents > max_ents))
260 return -EINVAL;
Jens Axboe0db92992007-11-30 09:16:50 +0100261#endif
262
Jens Axboe0db92992007-11-30 09:16:50 +0100263 left = nents;
264 prv = NULL;
265 do {
266 unsigned int sg_size, alloc_size = left;
267
James Bottomley7cedb1f2008-01-13 14:15:28 -0600268 if (alloc_size > max_ents) {
269 alloc_size = max_ents;
Jens Axboe0db92992007-11-30 09:16:50 +0100270 sg_size = alloc_size - 1;
271 } else
272 sg_size = alloc_size;
273
274 left -= sg_size;
275
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200276 if (first_chunk) {
277 sg = first_chunk;
278 first_chunk = NULL;
279 } else {
280 sg = alloc_fn(alloc_size, gfp_mask);
281 }
Jeffrey Carlyleedce6822010-08-30 19:55:09 +0200282 if (unlikely(!sg)) {
283 /*
284 * Adjust entry count to reflect that the last
285 * entry of the previous table won't be used for
286 * linkage. Without this, sg_kfree() may get
287 * confused.
288 */
289 if (prv)
290 table->nents = ++table->orig_nents;
291
292 return -ENOMEM;
293 }
Jens Axboe0db92992007-11-30 09:16:50 +0100294
295 sg_init_table(sg, alloc_size);
296 table->nents = table->orig_nents += sg_size;
297
298 /*
299 * If this is the first mapping, assign the sg table header.
300 * If this is not the first mapping, chain previous part.
301 */
302 if (prv)
James Bottomley7cedb1f2008-01-13 14:15:28 -0600303 sg_chain(prv, max_ents, sg);
Jens Axboe0db92992007-11-30 09:16:50 +0100304 else
305 table->sgl = sg;
306
307 /*
308 * If no more entries after this one, mark the end
309 */
310 if (!left)
311 sg_mark_end(&sg[sg_size - 1]);
312
Jens Axboe0db92992007-11-30 09:16:50 +0100313 prv = sg;
314 } while (left);
315
316 return 0;
317}
318EXPORT_SYMBOL(__sg_alloc_table);
319
320/**
321 * sg_alloc_table - Allocate and initialize an sg table
322 * @table: The sg table header to use
323 * @nents: Number of entries in sg list
324 * @gfp_mask: GFP allocation mask
325 *
326 * Description:
327 * Allocate and initialize an sg table. If @nents@ is larger than
328 * SG_MAX_SINGLE_ALLOC a chained sg table will be setup.
329 *
330 **/
331int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
332{
333 int ret;
334
James Bottomley7cedb1f2008-01-13 14:15:28 -0600335 ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200336 NULL, gfp_mask, sg_kmalloc);
Jens Axboe0db92992007-11-30 09:16:50 +0100337 if (unlikely(ret))
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200338 __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);
Jens Axboe0db92992007-11-30 09:16:50 +0100339
340 return ret;
341}
342EXPORT_SYMBOL(sg_alloc_table);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900343
344/**
Tomasz Stanislawskiefc42bc2012-06-18 09:25:01 +0200345 * sg_alloc_table_from_pages - Allocate and initialize an sg table from
346 * an array of pages
347 * @sgt: The sg table header to use
348 * @pages: Pointer to an array of page pointers
349 * @n_pages: Number of pages in the pages array
350 * @offset: Offset from start of the first page to the start of a buffer
351 * @size: Number of valid bytes in the buffer (after offset)
352 * @gfp_mask: GFP allocation mask
353 *
354 * Description:
355 * Allocate and initialize an sg table from a list of pages. Contiguous
356 * ranges of the pages are squashed into a single scatterlist node. A user
357 * may provide an offset at a start and a size of valid data in a buffer
358 * specified by the page array. The returned sg table is released by
359 * sg_free_table.
360 *
361 * Returns:
362 * 0 on success, negative error on failure
363 */
364int sg_alloc_table_from_pages(struct sg_table *sgt,
365 struct page **pages, unsigned int n_pages,
366 unsigned long offset, unsigned long size,
367 gfp_t gfp_mask)
368{
369 unsigned int chunks;
370 unsigned int i;
371 unsigned int cur_page;
372 int ret;
373 struct scatterlist *s;
374
375 /* compute number of contiguous chunks */
376 chunks = 1;
377 for (i = 1; i < n_pages; ++i)
378 if (page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1)
379 ++chunks;
380
381 ret = sg_alloc_table(sgt, chunks, gfp_mask);
382 if (unlikely(ret))
383 return ret;
384
385 /* merging chunks and putting them into the scatterlist */
386 cur_page = 0;
387 for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
388 unsigned long chunk_size;
389 unsigned int j;
390
391 /* look for the end of the current chunk */
392 for (j = cur_page + 1; j < n_pages; ++j)
393 if (page_to_pfn(pages[j]) !=
394 page_to_pfn(pages[j - 1]) + 1)
395 break;
396
397 chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset;
398 sg_set_page(s, pages[cur_page], min(size, chunk_size), offset);
399 size -= chunk_size;
400 offset = 0;
401 cur_page = j;
402 }
403
404 return 0;
405}
406EXPORT_SYMBOL(sg_alloc_table_from_pages);
407
Imre Deaka321e912013-02-27 17:02:56 -0800408void __sg_page_iter_start(struct sg_page_iter *piter,
409 struct scatterlist *sglist, unsigned int nents,
410 unsigned long pgoffset)
411{
412 piter->__pg_advance = 0;
413 piter->__nents = nents;
414
Imre Deaka321e912013-02-27 17:02:56 -0800415 piter->sg = sglist;
416 piter->sg_pgoffset = pgoffset;
417}
418EXPORT_SYMBOL(__sg_page_iter_start);
419
420static int sg_page_count(struct scatterlist *sg)
421{
422 return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT;
423}
424
425bool __sg_page_iter_next(struct sg_page_iter *piter)
426{
427 if (!piter->__nents || !piter->sg)
428 return false;
429
430 piter->sg_pgoffset += piter->__pg_advance;
431 piter->__pg_advance = 1;
432
433 while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {
434 piter->sg_pgoffset -= sg_page_count(piter->sg);
435 piter->sg = sg_next(piter->sg);
436 if (!--piter->__nents || !piter->sg)
437 return false;
438 }
Imre Deaka321e912013-02-27 17:02:56 -0800439
440 return true;
441}
442EXPORT_SYMBOL(__sg_page_iter_next);
443
Tomasz Stanislawskiefc42bc2012-06-18 09:25:01 +0200444/**
Tejun Heo137d3ed2008-07-19 23:03:35 +0900445 * sg_miter_start - start mapping iteration over a sg list
446 * @miter: sg mapping iter to be started
447 * @sgl: sg list to iterate over
448 * @nents: number of sg entries
449 *
450 * Description:
451 * Starts mapping iterator @miter.
452 *
453 * Context:
454 * Don't care.
455 */
456void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
457 unsigned int nents, unsigned int flags)
458{
459 memset(miter, 0, sizeof(struct sg_mapping_iter));
460
Imre Deak4225fc82013-02-27 17:02:57 -0800461 __sg_page_iter_start(&miter->piter, sgl, nents, 0);
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200462 WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG)));
Tejun Heo137d3ed2008-07-19 23:03:35 +0900463 miter->__flags = flags;
464}
465EXPORT_SYMBOL(sg_miter_start);
466
Akinobu Mita11052002013-07-08 16:01:52 -0700467static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)
468{
469 if (!miter->__remaining) {
470 struct scatterlist *sg;
471 unsigned long pgoffset;
472
473 if (!__sg_page_iter_next(&miter->piter))
474 return false;
475
476 sg = miter->piter.sg;
477 pgoffset = miter->piter.sg_pgoffset;
478
479 miter->__offset = pgoffset ? 0 : sg->offset;
480 miter->__remaining = sg->offset + sg->length -
481 (pgoffset << PAGE_SHIFT) - miter->__offset;
482 miter->__remaining = min_t(unsigned long, miter->__remaining,
483 PAGE_SIZE - miter->__offset);
484 }
485
486 return true;
487}
488
Tejun Heo137d3ed2008-07-19 23:03:35 +0900489/**
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700490 * sg_miter_skip - reposition mapping iterator
491 * @miter: sg mapping iter to be skipped
492 * @offset: number of bytes to plus the current location
493 *
494 * Description:
495 * Sets the offset of @miter to its current location plus @offset bytes.
496 * If mapping iterator @miter has been proceeded by sg_miter_next(), this
497 * stops @miter.
498 *
499 * Context:
500 * Don't care if @miter is stopped, or not proceeded yet.
501 * Otherwise, preemption disabled if the SG_MITER_ATOMIC is set.
502 *
503 * Returns:
504 * true if @miter contains the valid mapping. false if end of sg
505 * list is reached.
506 */
Ming Lei0d6077f2013-11-26 12:43:37 +0800507bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset)
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700508{
509 sg_miter_stop(miter);
510
511 while (offset) {
512 off_t consumed;
513
514 if (!sg_miter_get_next_page(miter))
515 return false;
516
517 consumed = min_t(off_t, offset, miter->__remaining);
518 miter->__offset += consumed;
519 miter->__remaining -= consumed;
520 offset -= consumed;
521 }
522
523 return true;
524}
Ming Lei0d6077f2013-11-26 12:43:37 +0800525EXPORT_SYMBOL(sg_miter_skip);
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700526
527/**
Tejun Heo137d3ed2008-07-19 23:03:35 +0900528 * sg_miter_next - proceed mapping iterator to the next mapping
529 * @miter: sg mapping iter to proceed
530 *
531 * Description:
Tejun Heo8290e2d2012-10-04 17:13:28 -0700532 * Proceeds @miter to the next mapping. @miter should have been started
533 * using sg_miter_start(). On successful return, @miter->page,
534 * @miter->addr and @miter->length point to the current mapping.
Tejun Heo137d3ed2008-07-19 23:03:35 +0900535 *
536 * Context:
Tejun Heo8290e2d2012-10-04 17:13:28 -0700537 * Preemption disabled if SG_MITER_ATOMIC. Preemption must stay disabled
538 * till @miter is stopped. May sleep if !SG_MITER_ATOMIC.
Tejun Heo137d3ed2008-07-19 23:03:35 +0900539 *
540 * Returns:
541 * true if @miter contains the next mapping. false if end of sg
542 * list is reached.
543 */
544bool sg_miter_next(struct sg_mapping_iter *miter)
545{
Tejun Heo137d3ed2008-07-19 23:03:35 +0900546 sg_miter_stop(miter);
547
Imre Deak4225fc82013-02-27 17:02:57 -0800548 /*
549 * Get to the next page if necessary.
550 * __remaining, __offset is adjusted by sg_miter_stop
551 */
Akinobu Mita11052002013-07-08 16:01:52 -0700552 if (!sg_miter_get_next_page(miter))
553 return false;
Imre Deak4225fc82013-02-27 17:02:57 -0800554
Imre Deak2db76d72013-03-26 15:14:18 +0200555 miter->page = sg_page_iter_page(&miter->piter);
Imre Deak4225fc82013-02-27 17:02:57 -0800556 miter->consumed = miter->length = miter->__remaining;
Tejun Heo137d3ed2008-07-19 23:03:35 +0900557
558 if (miter->__flags & SG_MITER_ATOMIC)
Imre Deak4225fc82013-02-27 17:02:57 -0800559 miter->addr = kmap_atomic(miter->page) + miter->__offset;
Tejun Heo137d3ed2008-07-19 23:03:35 +0900560 else
Imre Deak4225fc82013-02-27 17:02:57 -0800561 miter->addr = kmap(miter->page) + miter->__offset;
Tejun Heo137d3ed2008-07-19 23:03:35 +0900562
563 return true;
564}
565EXPORT_SYMBOL(sg_miter_next);
566
567/**
568 * sg_miter_stop - stop mapping iteration
569 * @miter: sg mapping iter to be stopped
570 *
571 * Description:
572 * Stops mapping iterator @miter. @miter should have been started
573 * started using sg_miter_start(). A stopped iteration can be
574 * resumed by calling sg_miter_next() on it. This is useful when
575 * resources (kmap) need to be released during iteration.
576 *
577 * Context:
Tejun Heo8290e2d2012-10-04 17:13:28 -0700578 * Preemption disabled if the SG_MITER_ATOMIC is set. Don't care
579 * otherwise.
Tejun Heo137d3ed2008-07-19 23:03:35 +0900580 */
581void sg_miter_stop(struct sg_mapping_iter *miter)
582{
583 WARN_ON(miter->consumed > miter->length);
584
585 /* drop resources from the last iteration */
586 if (miter->addr) {
587 miter->__offset += miter->consumed;
Imre Deak4225fc82013-02-27 17:02:57 -0800588 miter->__remaining -= miter->consumed;
Tejun Heo137d3ed2008-07-19 23:03:35 +0900589
Ming Lei3d77b502013-10-31 16:34:17 -0700590 if ((miter->__flags & SG_MITER_TO_SG) &&
591 !PageSlab(miter->page))
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200592 flush_kernel_dcache_page(miter->page);
593
Tejun Heo137d3ed2008-07-19 23:03:35 +0900594 if (miter->__flags & SG_MITER_ATOMIC) {
Tejun Heo8290e2d2012-10-04 17:13:28 -0700595 WARN_ON_ONCE(preemptible());
Cong Wangc3eede82011-11-25 23:14:39 +0800596 kunmap_atomic(miter->addr);
Tejun Heo137d3ed2008-07-19 23:03:35 +0900597 } else
Arjan van de Venf652c522008-11-19 15:36:19 -0800598 kunmap(miter->page);
Tejun Heo137d3ed2008-07-19 23:03:35 +0900599
600 miter->page = NULL;
601 miter->addr = NULL;
602 miter->length = 0;
603 miter->consumed = 0;
604 }
605}
606EXPORT_SYMBOL(sg_miter_stop);
607
608/**
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900609 * sg_copy_buffer - Copy data between a linear buffer and an SG list
610 * @sgl: The SG list
611 * @nents: Number of SG entries
612 * @buf: Where to copy from
613 * @buflen: The number of bytes to copy
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700614 * @skip: Number of bytes to skip before copying
615 * @to_buffer: transfer direction (true == from an sg list to a
616 * buffer, false == from a buffer to an sg list
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900617 *
618 * Returns the number of copied bytes.
619 *
620 **/
621static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents,
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700622 void *buf, size_t buflen, off_t skip,
623 bool to_buffer)
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900624{
Tejun Heo137d3ed2008-07-19 23:03:35 +0900625 unsigned int offset = 0;
626 struct sg_mapping_iter miter;
FUJITA Tomonori50bed2e2008-09-11 18:35:39 +0200627 unsigned long flags;
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200628 unsigned int sg_flags = SG_MITER_ATOMIC;
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900629
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200630 if (to_buffer)
631 sg_flags |= SG_MITER_FROM_SG;
632 else
633 sg_flags |= SG_MITER_TO_SG;
634
635 sg_miter_start(&miter, sgl, nents, sg_flags);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900636
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700637 if (!sg_miter_skip(&miter, skip))
638 return false;
639
FUJITA Tomonori50bed2e2008-09-11 18:35:39 +0200640 local_irq_save(flags);
641
Tejun Heo137d3ed2008-07-19 23:03:35 +0900642 while (sg_miter_next(&miter) && offset < buflen) {
643 unsigned int len;
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900644
Tejun Heo137d3ed2008-07-19 23:03:35 +0900645 len = min(miter.length, buflen - offset);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900646
Tejun Heo137d3ed2008-07-19 23:03:35 +0900647 if (to_buffer)
648 memcpy(buf + offset, miter.addr, len);
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200649 else
Tejun Heo137d3ed2008-07-19 23:03:35 +0900650 memcpy(miter.addr, buf + offset, len);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900651
Tejun Heo137d3ed2008-07-19 23:03:35 +0900652 offset += len;
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900653 }
654
Tejun Heo137d3ed2008-07-19 23:03:35 +0900655 sg_miter_stop(&miter);
656
FUJITA Tomonori50bed2e2008-09-11 18:35:39 +0200657 local_irq_restore(flags);
Tejun Heo137d3ed2008-07-19 23:03:35 +0900658 return offset;
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900659}
660
661/**
662 * sg_copy_from_buffer - Copy from a linear buffer to an SG list
663 * @sgl: The SG list
664 * @nents: Number of SG entries
665 * @buf: Where to copy from
666 * @buflen: The number of bytes to copy
667 *
668 * Returns the number of copied bytes.
669 *
670 **/
671size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
672 void *buf, size_t buflen)
673{
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700674 return sg_copy_buffer(sgl, nents, buf, buflen, 0, false);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900675}
676EXPORT_SYMBOL(sg_copy_from_buffer);
677
678/**
679 * sg_copy_to_buffer - Copy from an SG list to a linear buffer
680 * @sgl: The SG list
681 * @nents: Number of SG entries
682 * @buf: Where to copy to
683 * @buflen: The number of bytes to copy
684 *
685 * Returns the number of copied bytes.
686 *
687 **/
688size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
689 void *buf, size_t buflen)
690{
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700691 return sg_copy_buffer(sgl, nents, buf, buflen, 0, true);
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900692}
693EXPORT_SYMBOL(sg_copy_to_buffer);
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700694
695/**
696 * sg_pcopy_from_buffer - Copy from a linear buffer to an SG list
697 * @sgl: The SG list
698 * @nents: Number of SG entries
699 * @buf: Where to copy from
700 * @skip: Number of bytes to skip before copying
701 * @buflen: The number of bytes to copy
702 *
703 * Returns the number of copied bytes.
704 *
705 **/
706size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
707 void *buf, size_t buflen, off_t skip)
708{
709 return sg_copy_buffer(sgl, nents, buf, buflen, skip, false);
710}
711EXPORT_SYMBOL(sg_pcopy_from_buffer);
712
713/**
714 * sg_pcopy_to_buffer - Copy from an SG list to a linear buffer
715 * @sgl: The SG list
716 * @nents: Number of SG entries
717 * @buf: Where to copy to
718 * @skip: Number of bytes to skip before copying
719 * @buflen: The number of bytes to copy
720 *
721 * Returns the number of copied bytes.
722 *
723 **/
724size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
725 void *buf, size_t buflen, off_t skip)
726{
727 return sg_copy_buffer(sgl, nents, buf, buflen, skip, true);
728}
729EXPORT_SYMBOL(sg_pcopy_to_buffer);