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0db9299f JA |
1 | /* |
2 | * Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com> | |
3 | * | |
4 | * Scatterlist handling helpers. | |
5 | * | |
6 | * This source code is licensed under the GNU General Public License, | |
7 | * Version 2. See the file COPYING for more details. | |
8 | */ | |
8bc3bcc9 | 9 | #include <linux/export.h> |
5a0e3ad6 | 10 | #include <linux/slab.h> |
0db9299f | 11 | #include <linux/scatterlist.h> |
b1adaf65 | 12 | #include <linux/highmem.h> |
b94de9bb | 13 | #include <linux/kmemleak.h> |
0db9299f JA |
14 | |
15 | /** | |
16 | * sg_next - return the next scatterlist entry in a list | |
17 | * @sg: The current sg entry | |
18 | * | |
19 | * Description: | |
20 | * Usually the next entry will be @sg@ + 1, but if this sg element is part | |
21 | * of a chained scatterlist, it could jump to the start of a new | |
22 | * scatterlist array. | |
23 | * | |
24 | **/ | |
25 | struct 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 | } | |
39 | EXPORT_SYMBOL(sg_next); | |
40 | ||
2e484610 ML |
41 | /** |
42 | * sg_nents - return total count of entries in scatterlist | |
43 | * @sg: The scatterlist | |
44 | * | |
45 | * Description: | |
46 | * Allows to know how many entries are in sg, taking into acount | |
47 | * chaining as well | |
48 | * | |
49 | **/ | |
50 | int sg_nents(struct scatterlist *sg) | |
51 | { | |
232f1b51 ML |
52 | int nents; |
53 | for (nents = 0; sg; sg = sg_next(sg)) | |
2e484610 | 54 | nents++; |
2e484610 ML |
55 | return nents; |
56 | } | |
57 | EXPORT_SYMBOL(sg_nents); | |
58 | ||
cfaed10d TL |
59 | /** |
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 | **/ | |
73 | int 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 | } | |
90 | EXPORT_SYMBOL(sg_nents_for_len); | |
2e484610 | 91 | |
0db9299f JA |
92 | /** |
93 | * 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 | **/ | |
106 | struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents) | |
107 | { | |
0db9299f JA |
108 | struct scatterlist *sg, *ret = NULL; |
109 | unsigned int i; | |
110 | ||
111 | for_each_sg(sgl, sg, nents, i) | |
112 | ret = sg; | |
113 | ||
0db9299f JA |
114 | #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 | } | |
120 | EXPORT_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 | **/ | |
132 | void 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 | } | |
144 | EXPORT_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 | **/ | |
153 | void 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 | } | |
158 | EXPORT_SYMBOL(sg_init_one); | |
159 | ||
160 | /* | |
161 | * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree | |
162 | * helpers. | |
163 | */ | |
164 | static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask) | |
165 | { | |
b94de9bb CW |
166 | 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 | |
0db9299f JA |
180 | return kmalloc(nents * sizeof(struct scatterlist), gfp_mask); |
181 | } | |
182 | ||
183 | static void sg_kfree(struct scatterlist *sg, unsigned int nents) | |
184 | { | |
b94de9bb CW |
185 | if (nents == SG_MAX_SINGLE_ALLOC) { |
186 | kmemleak_free(sg); | |
0db9299f | 187 | free_page((unsigned long) sg); |
b94de9bb | 188 | } else |
0db9299f JA |
189 | kfree(sg); |
190 | } | |
191 | ||
192 | /** | |
193 | * __sg_free_table - Free a previously mapped sg table | |
194 | * @table: The sg table header to use | |
7cedb1f1 | 195 | * @max_ents: The maximum number of entries per single scatterlist |
c53c6d6a | 196 | * @skip_first_chunk: don't free the (preallocated) first scatterlist chunk |
0db9299f JA |
197 | * @free_fn: Free function |
198 | * | |
199 | * Description: | |
7cedb1f1 JB |
200 | * 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(). | |
0db9299f JA |
203 | * |
204 | **/ | |
7cedb1f1 | 205 | void __sg_free_table(struct sg_table *table, unsigned int max_ents, |
c53c6d6a | 206 | bool skip_first_chunk, sg_free_fn *free_fn) |
0db9299f JA |
207 | { |
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 | /* | |
7cedb1f1 | 219 | * If we have more than max_ents segments left, |
0db9299f JA |
220 | * 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 | */ | |
7cedb1f1 JB |
224 | if (alloc_size > max_ents) { |
225 | next = sg_chain_ptr(&sgl[max_ents - 1]); | |
226 | alloc_size = max_ents; | |
0db9299f JA |
227 | sg_size = alloc_size - 1; |
228 | } else { | |
229 | sg_size = alloc_size; | |
230 | next = NULL; | |
231 | } | |
232 | ||
233 | table->orig_nents -= sg_size; | |
c21e59d8 | 234 | if (skip_first_chunk) |
c53c6d6a | 235 | skip_first_chunk = false; |
c21e59d8 TB |
236 | else |
237 | free_fn(sgl, alloc_size); | |
0db9299f JA |
238 | sgl = next; |
239 | } | |
240 | ||
241 | table->sgl = NULL; | |
242 | } | |
243 | EXPORT_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 | **/ | |
250 | void sg_free_table(struct sg_table *table) | |
251 | { | |
c53c6d6a | 252 | __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree); |
0db9299f JA |
253 | } |
254 | EXPORT_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 | |
7cedb1f1 | 260 | * @max_ents: The maximum number of entries the allocator returns per call |
0db9299f JA |
261 | * @gfp_mask: GFP allocation mask |
262 | * @alloc_fn: Allocator to use | |
263 | * | |
7cedb1f1 JB |
264 | * 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 | * | |
0db9299f JA |
270 | * 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 | **/ | |
7cedb1f1 | 275 | int __sg_alloc_table(struct sg_table *table, unsigned int nents, |
c53c6d6a CH |
276 | unsigned int max_ents, struct scatterlist *first_chunk, |
277 | gfp_t gfp_mask, sg_alloc_fn *alloc_fn) | |
0db9299f JA |
278 | { |
279 | struct scatterlist *sg, *prv; | |
280 | unsigned int left; | |
281 | ||
27daabd9 DC |
282 | memset(table, 0, sizeof(*table)); |
283 | ||
284 | if (nents == 0) | |
285 | return -EINVAL; | |
308c09f1 | 286 | #ifndef CONFIG_ARCH_HAS_SG_CHAIN |
6fd59a83 NB |
287 | if (WARN_ON_ONCE(nents > max_ents)) |
288 | return -EINVAL; | |
0db9299f JA |
289 | #endif |
290 | ||
0db9299f JA |
291 | left = nents; |
292 | prv = NULL; | |
293 | do { | |
294 | unsigned int sg_size, alloc_size = left; | |
295 | ||
7cedb1f1 JB |
296 | if (alloc_size > max_ents) { |
297 | alloc_size = max_ents; | |
0db9299f JA |
298 | sg_size = alloc_size - 1; |
299 | } else | |
300 | sg_size = alloc_size; | |
301 | ||
302 | left -= sg_size; | |
303 | ||
c53c6d6a CH |
304 | if (first_chunk) { |
305 | sg = first_chunk; | |
306 | first_chunk = NULL; | |
307 | } else { | |
308 | sg = alloc_fn(alloc_size, gfp_mask); | |
309 | } | |
edce6820 JC |
310 | 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 | } | |
0db9299f JA |
322 | |
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) | |
7cedb1f1 | 331 | sg_chain(prv, max_ents, sg); |
0db9299f JA |
332 | 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 | ||
0db9299f JA |
341 | prv = sg; |
342 | } while (left); | |
343 | ||
344 | return 0; | |
345 | } | |
346 | EXPORT_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 | **/ | |
359 | int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) | |
360 | { | |
361 | int ret; | |
362 | ||
7cedb1f1 | 363 | ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC, |
c53c6d6a | 364 | NULL, gfp_mask, sg_kmalloc); |
0db9299f | 365 | if (unlikely(ret)) |
c53c6d6a | 366 | __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree); |
0db9299f JA |
367 | |
368 | return ret; | |
369 | } | |
370 | EXPORT_SYMBOL(sg_alloc_table); | |
b1adaf65 | 371 | |
efc42bc9 | 372 | /** |
89d8589c TU |
373 | * __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 | |
efc42bc9 TS |
382 | * |
383 | * Description: | |
384 | * Allocate and initialize an sg table from a list of pages. Contiguous | |
89d8589c TU |
385 | * 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. | |
efc42bc9 TS |
389 | * |
390 | * Returns: | |
391 | * 0 on success, negative error on failure | |
392 | */ | |
89d8589c TU |
393 | int __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) | |
efc42bc9 | 397 | { |
c125906b | 398 | unsigned int chunks, cur_page, seg_len, i; |
efc42bc9 TS |
399 | int ret; |
400 | struct scatterlist *s; | |
401 | ||
89d8589c TU |
402 | if (WARN_ON(!max_segment || offset_in_page(max_segment))) |
403 | return -EINVAL; | |
404 | ||
efc42bc9 TS |
405 | /* compute number of contiguous chunks */ |
406 | chunks = 1; | |
c125906b TU |
407 | 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 | } | |
efc42bc9 TS |
416 | |
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) { | |
c125906b | 424 | unsigned int j, chunk_size; |
efc42bc9 TS |
425 | |
426 | /* look for the end of the current chunk */ | |
c125906b TU |
427 | 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]) != | |
efc42bc9 TS |
432 | page_to_pfn(pages[j - 1]) + 1) |
433 | break; | |
c125906b | 434 | } |
efc42bc9 TS |
435 | |
436 | chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset; | |
c125906b TU |
437 | sg_set_page(s, pages[cur_page], |
438 | min_t(unsigned long, size, chunk_size), offset); | |
efc42bc9 TS |
439 | size -= chunk_size; |
440 | offset = 0; | |
441 | cur_page = j; | |
442 | } | |
443 | ||
444 | return 0; | |
445 | } | |
89d8589c TU |
446 | EXPORT_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 | */ | |
468 | int 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 | } | |
efc42bc9 TS |
475 | EXPORT_SYMBOL(sg_alloc_table_from_pages); |
476 | ||
a321e91b ID |
477 | void __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 | ||
a321e91b ID |
484 | piter->sg = sglist; |
485 | piter->sg_pgoffset = pgoffset; | |
486 | } | |
487 | EXPORT_SYMBOL(__sg_page_iter_start); | |
488 | ||
489 | static int sg_page_count(struct scatterlist *sg) | |
490 | { | |
491 | return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT; | |
492 | } | |
493 | ||
494 | bool __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 | } | |
a321e91b ID |
508 | |
509 | return true; | |
510 | } | |
511 | EXPORT_SYMBOL(__sg_page_iter_next); | |
512 | ||
137d3edb TH |
513 | /** |
514 | * 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 | */ | |
525 | void 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 | ||
4225fc85 | 530 | __sg_page_iter_start(&miter->piter, sgl, nents, 0); |
6de7e356 | 531 | WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG))); |
137d3edb TH |
532 | miter->__flags = flags; |
533 | } | |
534 | EXPORT_SYMBOL(sg_miter_start); | |
535 | ||
11052004 AM |
536 | static 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 | ||
df642cea AM |
558 | /** |
559 | * 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 | */ | |
0d6077f8 | 576 | bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset) |
df642cea AM |
577 | { |
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 | } | |
0d6077f8 | 594 | EXPORT_SYMBOL(sg_miter_skip); |
df642cea | 595 | |
137d3edb TH |
596 | /** |
597 | * sg_miter_next - proceed mapping iterator to the next mapping | |
598 | * @miter: sg mapping iter to proceed | |
599 | * | |
600 | * Description: | |
8290e2d2 TH |
601 | * 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. | |
137d3edb TH |
604 | * |
605 | * Context: | |
8290e2d2 TH |
606 | * Preemption disabled if SG_MITER_ATOMIC. Preemption must stay disabled |
607 | * till @miter is stopped. May sleep if !SG_MITER_ATOMIC. | |
137d3edb TH |
608 | * |
609 | * Returns: | |
610 | * true if @miter contains the next mapping. false if end of sg | |
611 | * list is reached. | |
612 | */ | |
613 | bool sg_miter_next(struct sg_mapping_iter *miter) | |
614 | { | |
137d3edb TH |
615 | sg_miter_stop(miter); |
616 | ||
4225fc85 ID |
617 | /* |
618 | * Get to the next page if necessary. | |
619 | * __remaining, __offset is adjusted by sg_miter_stop | |
620 | */ | |
11052004 AM |
621 | if (!sg_miter_get_next_page(miter)) |
622 | return false; | |
137d3edb | 623 | |
2db76d7c | 624 | miter->page = sg_page_iter_page(&miter->piter); |
4225fc85 | 625 | miter->consumed = miter->length = miter->__remaining; |
137d3edb TH |
626 | |
627 | if (miter->__flags & SG_MITER_ATOMIC) | |
4225fc85 | 628 | miter->addr = kmap_atomic(miter->page) + miter->__offset; |
137d3edb | 629 | else |
4225fc85 | 630 | miter->addr = kmap(miter->page) + miter->__offset; |
137d3edb TH |
631 | |
632 | return true; | |
633 | } | |
634 | EXPORT_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 | |
4ba6a2b2 MY |
642 | * 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. | |
137d3edb TH |
645 | * |
646 | * Context: | |
8290e2d2 TH |
647 | * Preemption disabled if the SG_MITER_ATOMIC is set. Don't care |
648 | * otherwise. | |
137d3edb TH |
649 | */ |
650 | void 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; | |
4225fc85 | 657 | miter->__remaining -= miter->consumed; |
137d3edb | 658 | |
3d77b50c ML |
659 | if ((miter->__flags & SG_MITER_TO_SG) && |
660 | !PageSlab(miter->page)) | |
6de7e356 SAS |
661 | flush_kernel_dcache_page(miter->page); |
662 | ||
137d3edb | 663 | if (miter->__flags & SG_MITER_ATOMIC) { |
8290e2d2 | 664 | WARN_ON_ONCE(preemptible()); |
c3eede8e | 665 | kunmap_atomic(miter->addr); |
137d3edb | 666 | } else |
f652c521 | 667 | kunmap(miter->page); |
137d3edb TH |
668 | |
669 | miter->page = NULL; | |
670 | miter->addr = NULL; | |
671 | miter->length = 0; | |
672 | miter->consumed = 0; | |
673 | } | |
674 | } | |
675 | EXPORT_SYMBOL(sg_miter_stop); | |
676 | ||
b1adaf65 FT |
677 | /** |
678 | * 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 | |
df642cea AM |
683 | * @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 | |
b1adaf65 FT |
686 | * |
687 | * Returns the number of copied bytes. | |
688 | * | |
689 | **/ | |
386ecb12 DG |
690 | size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, |
691 | size_t buflen, off_t skip, bool to_buffer) | |
b1adaf65 | 692 | { |
137d3edb TH |
693 | unsigned int offset = 0; |
694 | struct sg_mapping_iter miter; | |
6de7e356 SAS |
695 | unsigned int sg_flags = SG_MITER_ATOMIC; |
696 | ||
697 | if (to_buffer) | |
698 | sg_flags |= SG_MITER_FROM_SG; | |
699 | else | |
700 | sg_flags |= SG_MITER_TO_SG; | |
137d3edb | 701 | |
6de7e356 | 702 | sg_miter_start(&miter, sgl, nents, sg_flags); |
137d3edb | 703 | |
df642cea AM |
704 | if (!sg_miter_skip(&miter, skip)) |
705 | return false; | |
706 | ||
1d5210ef | 707 | while ((offset < buflen) && sg_miter_next(&miter)) { |
137d3edb TH |
708 | unsigned int len; |
709 | ||
710 | len = min(miter.length, buflen - offset); | |
711 | ||
712 | if (to_buffer) | |
713 | memcpy(buf + offset, miter.addr, len); | |
6de7e356 | 714 | else |
137d3edb | 715 | memcpy(miter.addr, buf + offset, len); |
b1adaf65 | 716 | |
137d3edb | 717 | offset += len; |
b1adaf65 FT |
718 | } |
719 | ||
137d3edb TH |
720 | sg_miter_stop(&miter); |
721 | ||
722 | return offset; | |
b1adaf65 | 723 | } |
386ecb12 | 724 | EXPORT_SYMBOL(sg_copy_buffer); |
b1adaf65 FT |
725 | |
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 | **/ | |
736 | size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, | |
2a1bf8f9 | 737 | const void *buf, size_t buflen) |
b1adaf65 | 738 | { |
2a1bf8f9 | 739 | return sg_copy_buffer(sgl, nents, (void *)buf, buflen, 0, false); |
b1adaf65 FT |
740 | } |
741 | EXPORT_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 | **/ | |
753 | size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, | |
754 | void *buf, size_t buflen) | |
755 | { | |
df642cea | 756 | return sg_copy_buffer(sgl, nents, buf, buflen, 0, true); |
b1adaf65 FT |
757 | } |
758 | EXPORT_SYMBOL(sg_copy_to_buffer); | |
df642cea AM |
759 | |
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 | |
df642cea | 765 | * @buflen: The number of bytes to copy |
4dc7daf8 | 766 | * @skip: Number of bytes to skip before copying |
df642cea AM |
767 | * |
768 | * Returns the number of copied bytes. | |
769 | * | |
770 | **/ | |
771 | size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, | |
2a1bf8f9 | 772 | const void *buf, size_t buflen, off_t skip) |
df642cea | 773 | { |
2a1bf8f9 | 774 | return sg_copy_buffer(sgl, nents, (void *)buf, buflen, skip, false); |
df642cea AM |
775 | } |
776 | EXPORT_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 | |
df642cea | 783 | * @buflen: The number of bytes to copy |
4dc7daf8 | 784 | * @skip: Number of bytes to skip before copying |
df642cea AM |
785 | * |
786 | * Returns the number of copied bytes. | |
787 | * | |
788 | **/ | |
789 | size_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 | } | |
794 | EXPORT_SYMBOL(sg_pcopy_to_buffer); | |
0945e569 JT |
795 | |
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 | **/ | |
805 | size_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 | } | |
829 | EXPORT_SYMBOL(sg_zero_buffer); |