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40b0b3f8 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
0db9299f JA |
2 | /* |
3 | * Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com> | |
4 | * | |
5 | * Scatterlist handling helpers. | |
0db9299f | 6 | */ |
8bc3bcc9 | 7 | #include <linux/export.h> |
5a0e3ad6 | 8 | #include <linux/slab.h> |
0db9299f | 9 | #include <linux/scatterlist.h> |
b1adaf65 | 10 | #include <linux/highmem.h> |
b94de9bb | 11 | #include <linux/kmemleak.h> |
0db9299f JA |
12 | |
13 | /** | |
14 | * sg_next - return the next scatterlist entry in a list | |
15 | * @sg: The current sg entry | |
16 | * | |
17 | * Description: | |
18 | * Usually the next entry will be @sg@ + 1, but if this sg element is part | |
19 | * of a chained scatterlist, it could jump to the start of a new | |
20 | * scatterlist array. | |
21 | * | |
22 | **/ | |
23 | struct scatterlist *sg_next(struct scatterlist *sg) | |
24 | { | |
0db9299f JA |
25 | if (sg_is_last(sg)) |
26 | return NULL; | |
27 | ||
28 | sg++; | |
29 | if (unlikely(sg_is_chain(sg))) | |
30 | sg = sg_chain_ptr(sg); | |
31 | ||
32 | return sg; | |
33 | } | |
34 | EXPORT_SYMBOL(sg_next); | |
35 | ||
2e484610 ML |
36 | /** |
37 | * sg_nents - return total count of entries in scatterlist | |
38 | * @sg: The scatterlist | |
39 | * | |
40 | * Description: | |
9dbbc3b9 | 41 | * Allows to know how many entries are in sg, taking into account |
2e484610 ML |
42 | * chaining as well |
43 | * | |
44 | **/ | |
45 | int sg_nents(struct scatterlist *sg) | |
46 | { | |
232f1b51 ML |
47 | int nents; |
48 | for (nents = 0; sg; sg = sg_next(sg)) | |
2e484610 | 49 | nents++; |
2e484610 ML |
50 | return nents; |
51 | } | |
52 | EXPORT_SYMBOL(sg_nents); | |
53 | ||
cfaed10d TL |
54 | /** |
55 | * sg_nents_for_len - return total count of entries in scatterlist | |
56 | * needed to satisfy the supplied length | |
57 | * @sg: The scatterlist | |
58 | * @len: The total required length | |
59 | * | |
60 | * Description: | |
61 | * Determines the number of entries in sg that are required to meet | |
9dbbc3b9 | 62 | * the supplied length, taking into account chaining as well |
cfaed10d TL |
63 | * |
64 | * Returns: | |
65 | * the number of sg entries needed, negative error on failure | |
66 | * | |
67 | **/ | |
68 | int sg_nents_for_len(struct scatterlist *sg, u64 len) | |
69 | { | |
70 | int nents; | |
71 | u64 total; | |
72 | ||
73 | if (!len) | |
74 | return 0; | |
75 | ||
76 | for (nents = 0, total = 0; sg; sg = sg_next(sg)) { | |
77 | nents++; | |
78 | total += sg->length; | |
79 | if (total >= len) | |
80 | return nents; | |
81 | } | |
82 | ||
83 | return -EINVAL; | |
84 | } | |
85 | EXPORT_SYMBOL(sg_nents_for_len); | |
2e484610 | 86 | |
0db9299f JA |
87 | /** |
88 | * sg_last - return the last scatterlist entry in a list | |
89 | * @sgl: First entry in the scatterlist | |
90 | * @nents: Number of entries in the scatterlist | |
91 | * | |
92 | * Description: | |
93 | * Should only be used casually, it (currently) scans the entire list | |
94 | * to get the last entry. | |
95 | * | |
96 | * Note that the @sgl@ pointer passed in need not be the first one, | |
97 | * the important bit is that @nents@ denotes the number of entries that | |
98 | * exist from @sgl@. | |
99 | * | |
100 | **/ | |
101 | struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents) | |
102 | { | |
0db9299f JA |
103 | struct scatterlist *sg, *ret = NULL; |
104 | unsigned int i; | |
105 | ||
106 | for_each_sg(sgl, sg, nents, i) | |
107 | ret = sg; | |
108 | ||
0db9299f | 109 | BUG_ON(!sg_is_last(ret)); |
0db9299f JA |
110 | return ret; |
111 | } | |
112 | EXPORT_SYMBOL(sg_last); | |
113 | ||
114 | /** | |
115 | * sg_init_table - Initialize SG table | |
116 | * @sgl: The SG table | |
117 | * @nents: Number of entries in table | |
118 | * | |
119 | * Notes: | |
120 | * If this is part of a chained sg table, sg_mark_end() should be | |
121 | * used only on the last table part. | |
122 | * | |
123 | **/ | |
124 | void sg_init_table(struct scatterlist *sgl, unsigned int nents) | |
125 | { | |
126 | memset(sgl, 0, sizeof(*sgl) * nents); | |
f3851786 | 127 | sg_init_marker(sgl, nents); |
0db9299f JA |
128 | } |
129 | EXPORT_SYMBOL(sg_init_table); | |
130 | ||
131 | /** | |
132 | * sg_init_one - Initialize a single entry sg list | |
133 | * @sg: SG entry | |
134 | * @buf: Virtual address for IO | |
135 | * @buflen: IO length | |
136 | * | |
137 | **/ | |
138 | void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen) | |
139 | { | |
140 | sg_init_table(sg, 1); | |
141 | sg_set_buf(sg, buf, buflen); | |
142 | } | |
143 | EXPORT_SYMBOL(sg_init_one); | |
144 | ||
145 | /* | |
146 | * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree | |
147 | * helpers. | |
148 | */ | |
149 | static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask) | |
150 | { | |
b94de9bb CW |
151 | if (nents == SG_MAX_SINGLE_ALLOC) { |
152 | /* | |
153 | * Kmemleak doesn't track page allocations as they are not | |
154 | * commonly used (in a raw form) for kernel data structures. | |
155 | * As we chain together a list of pages and then a normal | |
156 | * kmalloc (tracked by kmemleak), in order to for that last | |
157 | * allocation not to become decoupled (and thus a | |
158 | * false-positive) we need to inform kmemleak of all the | |
159 | * intermediate allocations. | |
160 | */ | |
161 | void *ptr = (void *) __get_free_page(gfp_mask); | |
162 | kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask); | |
163 | return ptr; | |
164 | } else | |
6da2ec56 KC |
165 | return kmalloc_array(nents, sizeof(struct scatterlist), |
166 | gfp_mask); | |
0db9299f JA |
167 | } |
168 | ||
169 | static void sg_kfree(struct scatterlist *sg, unsigned int nents) | |
170 | { | |
b94de9bb CW |
171 | if (nents == SG_MAX_SINGLE_ALLOC) { |
172 | kmemleak_free(sg); | |
0db9299f | 173 | free_page((unsigned long) sg); |
b94de9bb | 174 | } else |
0db9299f JA |
175 | kfree(sg); |
176 | } | |
177 | ||
178 | /** | |
179 | * __sg_free_table - Free a previously mapped sg table | |
180 | * @table: The sg table header to use | |
7cedb1f1 | 181 | * @max_ents: The maximum number of entries per single scatterlist |
4635873c ML |
182 | * @nents_first_chunk: Number of entries int the (preallocated) first |
183 | * scatterlist chunk, 0 means no such preallocated first chunk | |
0db9299f | 184 | * @free_fn: Free function |
3e302dbc | 185 | * @num_ents: Number of entries in the table |
0db9299f JA |
186 | * |
187 | * Description: | |
7cedb1f1 JB |
188 | * Free an sg table previously allocated and setup with |
189 | * __sg_alloc_table(). The @max_ents value must be identical to | |
190 | * that previously used with __sg_alloc_table(). | |
0db9299f JA |
191 | * |
192 | **/ | |
7cedb1f1 | 193 | void __sg_free_table(struct sg_table *table, unsigned int max_ents, |
3e302dbc MG |
194 | unsigned int nents_first_chunk, sg_free_fn *free_fn, |
195 | unsigned int num_ents) | |
0db9299f JA |
196 | { |
197 | struct scatterlist *sgl, *next; | |
4635873c | 198 | unsigned curr_max_ents = nents_first_chunk ?: max_ents; |
0db9299f JA |
199 | |
200 | if (unlikely(!table->sgl)) | |
201 | return; | |
202 | ||
203 | sgl = table->sgl; | |
3e302dbc MG |
204 | while (num_ents) { |
205 | unsigned int alloc_size = num_ents; | |
0db9299f JA |
206 | unsigned int sg_size; |
207 | ||
208 | /* | |
7cedb1f1 | 209 | * If we have more than max_ents segments left, |
0db9299f JA |
210 | * then assign 'next' to the sg table after the current one. |
211 | * sg_size is then one less than alloc size, since the last | |
212 | * element is the chain pointer. | |
213 | */ | |
4635873c ML |
214 | if (alloc_size > curr_max_ents) { |
215 | next = sg_chain_ptr(&sgl[curr_max_ents - 1]); | |
216 | alloc_size = curr_max_ents; | |
0db9299f JA |
217 | sg_size = alloc_size - 1; |
218 | } else { | |
219 | sg_size = alloc_size; | |
220 | next = NULL; | |
221 | } | |
222 | ||
3e302dbc | 223 | num_ents -= sg_size; |
4635873c ML |
224 | if (nents_first_chunk) |
225 | nents_first_chunk = 0; | |
c21e59d8 TB |
226 | else |
227 | free_fn(sgl, alloc_size); | |
0db9299f | 228 | sgl = next; |
4635873c | 229 | curr_max_ents = max_ents; |
0db9299f JA |
230 | } |
231 | ||
232 | table->sgl = NULL; | |
233 | } | |
234 | EXPORT_SYMBOL(__sg_free_table); | |
235 | ||
3e302dbc MG |
236 | /** |
237 | * sg_free_append_table - Free a previously allocated append sg table. | |
238 | * @table: The mapped sg append table header | |
239 | * | |
240 | **/ | |
241 | void sg_free_append_table(struct sg_append_table *table) | |
242 | { | |
6d529ea8 | 243 | __sg_free_table(&table->sgt, SG_MAX_SINGLE_ALLOC, 0, sg_kfree, |
3e302dbc MG |
244 | table->total_nents); |
245 | } | |
246 | EXPORT_SYMBOL(sg_free_append_table); | |
247 | ||
248 | ||
0db9299f JA |
249 | /** |
250 | * sg_free_table - Free a previously allocated sg table | |
251 | * @table: The mapped sg table header | |
252 | * | |
253 | **/ | |
254 | void sg_free_table(struct sg_table *table) | |
255 | { | |
6d529ea8 | 256 | __sg_free_table(table, SG_MAX_SINGLE_ALLOC, 0, sg_kfree, |
3e302dbc | 257 | table->orig_nents); |
0db9299f JA |
258 | } |
259 | EXPORT_SYMBOL(sg_free_table); | |
260 | ||
261 | /** | |
262 | * __sg_alloc_table - Allocate and initialize an sg table with given allocator | |
263 | * @table: The sg table header to use | |
264 | * @nents: Number of entries in sg list | |
7cedb1f1 | 265 | * @max_ents: The maximum number of entries the allocator returns per call |
4635873c ML |
266 | * @nents_first_chunk: Number of entries int the (preallocated) first |
267 | * scatterlist chunk, 0 means no such preallocated chunk provided by user | |
0db9299f JA |
268 | * @gfp_mask: GFP allocation mask |
269 | * @alloc_fn: Allocator to use | |
270 | * | |
7cedb1f1 JB |
271 | * Description: |
272 | * This function returns a @table @nents long. The allocator is | |
273 | * defined to return scatterlist chunks of maximum size @max_ents. | |
274 | * Thus if @nents is bigger than @max_ents, the scatterlists will be | |
275 | * chained in units of @max_ents. | |
276 | * | |
0db9299f JA |
277 | * Notes: |
278 | * If this function returns non-0 (eg failure), the caller must call | |
279 | * __sg_free_table() to cleanup any leftover allocations. | |
280 | * | |
281 | **/ | |
7cedb1f1 | 282 | int __sg_alloc_table(struct sg_table *table, unsigned int nents, |
c53c6d6a | 283 | unsigned int max_ents, struct scatterlist *first_chunk, |
4635873c ML |
284 | unsigned int nents_first_chunk, gfp_t gfp_mask, |
285 | sg_alloc_fn *alloc_fn) | |
0db9299f JA |
286 | { |
287 | struct scatterlist *sg, *prv; | |
288 | unsigned int left; | |
4635873c ML |
289 | unsigned curr_max_ents = nents_first_chunk ?: max_ents; |
290 | unsigned prv_max_ents; | |
0db9299f | 291 | |
27daabd9 DC |
292 | memset(table, 0, sizeof(*table)); |
293 | ||
294 | if (nents == 0) | |
295 | return -EINVAL; | |
7c703e54 | 296 | #ifdef CONFIG_ARCH_NO_SG_CHAIN |
6fd59a83 NB |
297 | if (WARN_ON_ONCE(nents > max_ents)) |
298 | return -EINVAL; | |
0db9299f JA |
299 | #endif |
300 | ||
0db9299f JA |
301 | left = nents; |
302 | prv = NULL; | |
303 | do { | |
304 | unsigned int sg_size, alloc_size = left; | |
305 | ||
4635873c ML |
306 | if (alloc_size > curr_max_ents) { |
307 | alloc_size = curr_max_ents; | |
0db9299f JA |
308 | sg_size = alloc_size - 1; |
309 | } else | |
310 | sg_size = alloc_size; | |
311 | ||
312 | left -= sg_size; | |
313 | ||
c53c6d6a CH |
314 | if (first_chunk) { |
315 | sg = first_chunk; | |
316 | first_chunk = NULL; | |
317 | } else { | |
318 | sg = alloc_fn(alloc_size, gfp_mask); | |
319 | } | |
edce6820 JC |
320 | if (unlikely(!sg)) { |
321 | /* | |
322 | * Adjust entry count to reflect that the last | |
323 | * entry of the previous table won't be used for | |
324 | * linkage. Without this, sg_kfree() may get | |
325 | * confused. | |
326 | */ | |
327 | if (prv) | |
328 | table->nents = ++table->orig_nents; | |
329 | ||
4e456fee | 330 | return -ENOMEM; |
edce6820 | 331 | } |
0db9299f JA |
332 | |
333 | sg_init_table(sg, alloc_size); | |
334 | table->nents = table->orig_nents += sg_size; | |
335 | ||
336 | /* | |
337 | * If this is the first mapping, assign the sg table header. | |
338 | * If this is not the first mapping, chain previous part. | |
339 | */ | |
340 | if (prv) | |
4635873c | 341 | sg_chain(prv, prv_max_ents, sg); |
0db9299f JA |
342 | else |
343 | table->sgl = sg; | |
344 | ||
345 | /* | |
346 | * If no more entries after this one, mark the end | |
347 | */ | |
348 | if (!left) | |
349 | sg_mark_end(&sg[sg_size - 1]); | |
350 | ||
0db9299f | 351 | prv = sg; |
4635873c ML |
352 | prv_max_ents = curr_max_ents; |
353 | curr_max_ents = max_ents; | |
0db9299f JA |
354 | } while (left); |
355 | ||
356 | return 0; | |
357 | } | |
358 | EXPORT_SYMBOL(__sg_alloc_table); | |
359 | ||
360 | /** | |
361 | * sg_alloc_table - Allocate and initialize an sg table | |
362 | * @table: The sg table header to use | |
363 | * @nents: Number of entries in sg list | |
364 | * @gfp_mask: GFP allocation mask | |
365 | * | |
366 | * Description: | |
367 | * Allocate and initialize an sg table. If @nents@ is larger than | |
368 | * SG_MAX_SINGLE_ALLOC a chained sg table will be setup. | |
369 | * | |
370 | **/ | |
371 | int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) | |
372 | { | |
373 | int ret; | |
374 | ||
7cedb1f1 | 375 | ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC, |
4635873c | 376 | NULL, 0, gfp_mask, sg_kmalloc); |
0db9299f | 377 | if (unlikely(ret)) |
3e302dbc | 378 | sg_free_table(table); |
0db9299f JA |
379 | return ret; |
380 | } | |
381 | EXPORT_SYMBOL(sg_alloc_table); | |
b1adaf65 | 382 | |
3e302dbc | 383 | static struct scatterlist *get_next_sg(struct sg_append_table *table, |
07da1223 MG |
384 | struct scatterlist *cur, |
385 | unsigned long needed_sges, | |
386 | gfp_t gfp_mask) | |
387 | { | |
388 | struct scatterlist *new_sg, *next_sg; | |
389 | unsigned int alloc_size; | |
390 | ||
391 | if (cur) { | |
392 | next_sg = sg_next(cur); | |
393 | /* Check if last entry should be keeped for chainning */ | |
394 | if (!sg_is_last(next_sg) || needed_sges == 1) | |
395 | return next_sg; | |
396 | } | |
397 | ||
398 | alloc_size = min_t(unsigned long, needed_sges, SG_MAX_SINGLE_ALLOC); | |
399 | new_sg = sg_kmalloc(alloc_size, gfp_mask); | |
400 | if (!new_sg) | |
401 | return ERR_PTR(-ENOMEM); | |
402 | sg_init_table(new_sg, alloc_size); | |
403 | if (cur) { | |
3e302dbc | 404 | table->total_nents += alloc_size - 1; |
07da1223 | 405 | __sg_chain(next_sg, new_sg); |
07da1223 | 406 | } else { |
3e302dbc MG |
407 | table->sgt.sgl = new_sg; |
408 | table->total_nents = alloc_size; | |
07da1223 MG |
409 | } |
410 | return new_sg; | |
411 | } | |
412 | ||
1567b49d LG |
413 | static bool pages_are_mergeable(struct page *a, struct page *b) |
414 | { | |
415 | if (page_to_pfn(a) != page_to_pfn(b) + 1) | |
416 | return false; | |
417 | if (!zone_device_pages_have_same_pgmap(a, b)) | |
418 | return false; | |
419 | return true; | |
420 | } | |
421 | ||
efc42bc9 | 422 | /** |
3e302dbc MG |
423 | * sg_alloc_append_table_from_pages - Allocate and initialize an append sg |
424 | * table from an array of pages | |
425 | * @sgt_append: The sg append table to use | |
426 | * @pages: Pointer to an array of page pointers | |
427 | * @n_pages: Number of pages in the pages array | |
89d8589c TU |
428 | * @offset: Offset from start of the first page to the start of a buffer |
429 | * @size: Number of valid bytes in the buffer (after offset) | |
9a40401c | 430 | * @max_segment: Maximum size of a scatterlist element in bytes |
07da1223 | 431 | * @left_pages: Left pages caller have to set after this call |
89d8589c | 432 | * @gfp_mask: GFP allocation mask |
efc42bc9 | 433 | * |
07da1223 | 434 | * Description: |
3e302dbc MG |
435 | * In the first call it allocate and initialize an sg table from a list of |
436 | * pages, else reuse the scatterlist from sgt_append. Contiguous ranges of | |
437 | * the pages are squashed into a single scatterlist entry up to the maximum | |
438 | * size specified in @max_segment. A user may provide an offset at a start | |
439 | * and a size of valid data in a buffer specified by the page array. The | |
440 | * returned sg table is released by sg_free_append_table | |
efc42bc9 TS |
441 | * |
442 | * Returns: | |
3e302dbc | 443 | * 0 on success, negative error on failure |
07da1223 MG |
444 | * |
445 | * Notes: | |
446 | * If this function returns non-0 (eg failure), the caller must call | |
3e302dbc MG |
447 | * sg_free_append_table() to cleanup any leftover allocations. |
448 | * | |
449 | * In the fist call, sgt_append must by initialized. | |
efc42bc9 | 450 | */ |
3e302dbc | 451 | int sg_alloc_append_table_from_pages(struct sg_append_table *sgt_append, |
07da1223 MG |
452 | struct page **pages, unsigned int n_pages, unsigned int offset, |
453 | unsigned long size, unsigned int max_segment, | |
3e302dbc | 454 | unsigned int left_pages, gfp_t gfp_mask) |
efc42bc9 | 455 | { |
07da1223 MG |
456 | unsigned int chunks, cur_page, seg_len, i, prv_len = 0; |
457 | unsigned int added_nents = 0; | |
3e302dbc | 458 | struct scatterlist *s = sgt_append->prv; |
1567b49d | 459 | struct page *last_pg; |
efc42bc9 | 460 | |
9a40401c JG |
461 | /* |
462 | * The algorithm below requires max_segment to be aligned to PAGE_SIZE | |
463 | * otherwise it can overshoot. | |
464 | */ | |
465 | max_segment = ALIGN_DOWN(max_segment, PAGE_SIZE); | |
466 | if (WARN_ON(max_segment < PAGE_SIZE)) | |
3e302dbc | 467 | return -EINVAL; |
07da1223 | 468 | |
3e302dbc MG |
469 | if (IS_ENABLED(CONFIG_ARCH_NO_SG_CHAIN) && sgt_append->prv) |
470 | return -EOPNOTSUPP; | |
07da1223 | 471 | |
3e302dbc | 472 | if (sgt_append->prv) { |
0f097f08 YH |
473 | unsigned long next_pfn = (page_to_phys(sg_page(sgt_append->prv)) + |
474 | sgt_append->prv->offset + sgt_append->prv->length) / PAGE_SIZE; | |
475 | ||
07da1223 | 476 | if (WARN_ON(offset)) |
3e302dbc | 477 | return -EINVAL; |
07da1223 MG |
478 | |
479 | /* Merge contiguous pages into the last SG */ | |
3e302dbc | 480 | prv_len = sgt_append->prv->length; |
0f097f08 YH |
481 | if (page_to_pfn(pages[0]) == next_pfn) { |
482 | last_pg = pfn_to_page(next_pfn - 1); | |
483 | while (n_pages && pages_are_mergeable(pages[0], last_pg)) { | |
484 | if (sgt_append->prv->length + PAGE_SIZE > max_segment) | |
485 | break; | |
486 | sgt_append->prv->length += PAGE_SIZE; | |
487 | last_pg = pages[0]; | |
488 | pages++; | |
489 | n_pages--; | |
490 | } | |
491 | if (!n_pages) | |
492 | goto out; | |
07da1223 | 493 | } |
07da1223 | 494 | } |
89d8589c | 495 | |
efc42bc9 TS |
496 | /* compute number of contiguous chunks */ |
497 | chunks = 1; | |
c125906b TU |
498 | seg_len = 0; |
499 | for (i = 1; i < n_pages; i++) { | |
500 | seg_len += PAGE_SIZE; | |
501 | if (seg_len >= max_segment || | |
1567b49d | 502 | !pages_are_mergeable(pages[i], pages[i - 1])) { |
c125906b TU |
503 | chunks++; |
504 | seg_len = 0; | |
505 | } | |
506 | } | |
efc42bc9 | 507 | |
efc42bc9 TS |
508 | /* merging chunks and putting them into the scatterlist */ |
509 | cur_page = 0; | |
07da1223 | 510 | for (i = 0; i < chunks; i++) { |
c125906b | 511 | unsigned int j, chunk_size; |
efc42bc9 TS |
512 | |
513 | /* look for the end of the current chunk */ | |
c125906b TU |
514 | seg_len = 0; |
515 | for (j = cur_page + 1; j < n_pages; j++) { | |
516 | seg_len += PAGE_SIZE; | |
517 | if (seg_len >= max_segment || | |
1567b49d | 518 | !pages_are_mergeable(pages[j], pages[j - 1])) |
efc42bc9 | 519 | break; |
c125906b | 520 | } |
efc42bc9 | 521 | |
07da1223 | 522 | /* Pass how many chunks might be left */ |
3e302dbc MG |
523 | s = get_next_sg(sgt_append, s, chunks - i + left_pages, |
524 | gfp_mask); | |
07da1223 MG |
525 | if (IS_ERR(s)) { |
526 | /* | |
527 | * Adjust entry length to be as before function was | |
528 | * called. | |
529 | */ | |
3e302dbc MG |
530 | if (sgt_append->prv) |
531 | sgt_append->prv->length = prv_len; | |
532 | return PTR_ERR(s); | |
07da1223 | 533 | } |
efc42bc9 | 534 | chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset; |
c125906b TU |
535 | sg_set_page(s, pages[cur_page], |
536 | min_t(unsigned long, size, chunk_size), offset); | |
07da1223 | 537 | added_nents++; |
efc42bc9 TS |
538 | size -= chunk_size; |
539 | offset = 0; | |
540 | cur_page = j; | |
541 | } | |
3e302dbc MG |
542 | sgt_append->sgt.nents += added_nents; |
543 | sgt_append->sgt.orig_nents = sgt_append->sgt.nents; | |
544 | sgt_append->prv = s; | |
07da1223 MG |
545 | out: |
546 | if (!left_pages) | |
547 | sg_mark_end(s); | |
3e302dbc | 548 | return 0; |
efc42bc9 | 549 | } |
90e7a6de | 550 | EXPORT_SYMBOL(sg_alloc_append_table_from_pages); |
89d8589c TU |
551 | |
552 | /** | |
90e7a6de MG |
553 | * sg_alloc_table_from_pages_segment - Allocate and initialize an sg table from |
554 | * an array of pages and given maximum | |
555 | * segment. | |
89d8589c TU |
556 | * @sgt: The sg table header to use |
557 | * @pages: Pointer to an array of page pointers | |
558 | * @n_pages: Number of pages in the pages array | |
559 | * @offset: Offset from start of the first page to the start of a buffer | |
560 | * @size: Number of valid bytes in the buffer (after offset) | |
90e7a6de | 561 | * @max_segment: Maximum size of a scatterlist element in bytes |
89d8589c TU |
562 | * @gfp_mask: GFP allocation mask |
563 | * | |
564 | * Description: | |
565 | * Allocate and initialize an sg table from a list of pages. Contiguous | |
90e7a6de MG |
566 | * ranges of the pages are squashed into a single scatterlist node up to the |
567 | * maximum size specified in @max_segment. A user may provide an offset at a | |
568 | * start and a size of valid data in a buffer specified by the page array. | |
89d8589c | 569 | * |
90e7a6de MG |
570 | * The returned sg table is released by sg_free_table. |
571 | * | |
572 | * Returns: | |
89d8589c TU |
573 | * 0 on success, negative error on failure |
574 | */ | |
90e7a6de MG |
575 | int sg_alloc_table_from_pages_segment(struct sg_table *sgt, struct page **pages, |
576 | unsigned int n_pages, unsigned int offset, | |
577 | unsigned long size, unsigned int max_segment, | |
578 | gfp_t gfp_mask) | |
89d8589c | 579 | { |
3e302dbc MG |
580 | struct sg_append_table append = {}; |
581 | int err; | |
582 | ||
583 | err = sg_alloc_append_table_from_pages(&append, pages, n_pages, offset, | |
584 | size, max_segment, 0, gfp_mask); | |
585 | if (err) { | |
586 | sg_free_append_table(&append); | |
587 | return err; | |
588 | } | |
589 | memcpy(sgt, &append.sgt, sizeof(*sgt)); | |
590 | WARN_ON(append.total_nents != sgt->orig_nents); | |
591 | return 0; | |
89d8589c | 592 | } |
90e7a6de | 593 | EXPORT_SYMBOL(sg_alloc_table_from_pages_segment); |
efc42bc9 | 594 | |
e80a0af4 BVA |
595 | #ifdef CONFIG_SGL_ALLOC |
596 | ||
597 | /** | |
598 | * sgl_alloc_order - allocate a scatterlist and its pages | |
599 | * @length: Length in bytes of the scatterlist. Must be at least one | |
600 | * @order: Second argument for alloc_pages() | |
601 | * @chainable: Whether or not to allocate an extra element in the scatterlist | |
602 | * for scatterlist chaining purposes | |
603 | * @gfp: Memory allocation flags | |
604 | * @nent_p: [out] Number of entries in the scatterlist that have pages | |
605 | * | |
606 | * Returns: A pointer to an initialized scatterlist or %NULL upon failure. | |
607 | */ | |
608 | struct scatterlist *sgl_alloc_order(unsigned long long length, | |
609 | unsigned int order, bool chainable, | |
610 | gfp_t gfp, unsigned int *nent_p) | |
611 | { | |
612 | struct scatterlist *sgl, *sg; | |
613 | struct page *page; | |
614 | unsigned int nent, nalloc; | |
615 | u32 elem_len; | |
616 | ||
617 | nent = round_up(length, PAGE_SIZE << order) >> (PAGE_SHIFT + order); | |
618 | /* Check for integer overflow */ | |
619 | if (length > (nent << (PAGE_SHIFT + order))) | |
620 | return NULL; | |
621 | nalloc = nent; | |
622 | if (chainable) { | |
623 | /* Check for integer overflow */ | |
624 | if (nalloc + 1 < nalloc) | |
625 | return NULL; | |
626 | nalloc++; | |
627 | } | |
628 | sgl = kmalloc_array(nalloc, sizeof(struct scatterlist), | |
6ed9b92e | 629 | gfp & ~GFP_DMA); |
e80a0af4 BVA |
630 | if (!sgl) |
631 | return NULL; | |
632 | ||
8c7a8d1c | 633 | sg_init_table(sgl, nalloc); |
e80a0af4 BVA |
634 | sg = sgl; |
635 | while (length) { | |
636 | elem_len = min_t(u64, length, PAGE_SIZE << order); | |
637 | page = alloc_pages(gfp, order); | |
638 | if (!page) { | |
b2a182a4 | 639 | sgl_free_order(sgl, order); |
e80a0af4 BVA |
640 | return NULL; |
641 | } | |
642 | ||
643 | sg_set_page(sg, page, elem_len, 0); | |
644 | length -= elem_len; | |
645 | sg = sg_next(sg); | |
646 | } | |
8c7a8d1c | 647 | WARN_ONCE(length, "length = %lld\n", length); |
e80a0af4 BVA |
648 | if (nent_p) |
649 | *nent_p = nent; | |
650 | return sgl; | |
651 | } | |
652 | EXPORT_SYMBOL(sgl_alloc_order); | |
653 | ||
654 | /** | |
655 | * sgl_alloc - allocate a scatterlist and its pages | |
656 | * @length: Length in bytes of the scatterlist | |
657 | * @gfp: Memory allocation flags | |
658 | * @nent_p: [out] Number of entries in the scatterlist | |
659 | * | |
660 | * Returns: A pointer to an initialized scatterlist or %NULL upon failure. | |
661 | */ | |
662 | struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp, | |
663 | unsigned int *nent_p) | |
664 | { | |
665 | return sgl_alloc_order(length, 0, false, gfp, nent_p); | |
666 | } | |
667 | EXPORT_SYMBOL(sgl_alloc); | |
668 | ||
669 | /** | |
8c7a8d1c | 670 | * sgl_free_n_order - free a scatterlist and its pages |
e80a0af4 | 671 | * @sgl: Scatterlist with one or more elements |
8c7a8d1c | 672 | * @nents: Maximum number of elements to free |
e80a0af4 | 673 | * @order: Second argument for __free_pages() |
8c7a8d1c BVA |
674 | * |
675 | * Notes: | |
676 | * - If several scatterlists have been chained and each chain element is | |
677 | * freed separately then it's essential to set nents correctly to avoid that a | |
678 | * page would get freed twice. | |
679 | * - All pages in a chained scatterlist can be freed at once by setting @nents | |
680 | * to a high number. | |
e80a0af4 | 681 | */ |
8c7a8d1c | 682 | void sgl_free_n_order(struct scatterlist *sgl, int nents, int order) |
e80a0af4 BVA |
683 | { |
684 | struct scatterlist *sg; | |
685 | struct page *page; | |
8c7a8d1c | 686 | int i; |
e80a0af4 | 687 | |
8c7a8d1c BVA |
688 | for_each_sg(sgl, sg, nents, i) { |
689 | if (!sg) | |
690 | break; | |
e80a0af4 BVA |
691 | page = sg_page(sg); |
692 | if (page) | |
693 | __free_pages(page, order); | |
694 | } | |
695 | kfree(sgl); | |
696 | } | |
8c7a8d1c BVA |
697 | EXPORT_SYMBOL(sgl_free_n_order); |
698 | ||
699 | /** | |
700 | * sgl_free_order - free a scatterlist and its pages | |
701 | * @sgl: Scatterlist with one or more elements | |
702 | * @order: Second argument for __free_pages() | |
703 | */ | |
704 | void sgl_free_order(struct scatterlist *sgl, int order) | |
705 | { | |
706 | sgl_free_n_order(sgl, INT_MAX, order); | |
707 | } | |
e80a0af4 BVA |
708 | EXPORT_SYMBOL(sgl_free_order); |
709 | ||
710 | /** | |
711 | * sgl_free - free a scatterlist and its pages | |
712 | * @sgl: Scatterlist with one or more elements | |
713 | */ | |
714 | void sgl_free(struct scatterlist *sgl) | |
715 | { | |
716 | sgl_free_order(sgl, 0); | |
717 | } | |
718 | EXPORT_SYMBOL(sgl_free); | |
719 | ||
720 | #endif /* CONFIG_SGL_ALLOC */ | |
721 | ||
a321e91b ID |
722 | void __sg_page_iter_start(struct sg_page_iter *piter, |
723 | struct scatterlist *sglist, unsigned int nents, | |
724 | unsigned long pgoffset) | |
725 | { | |
726 | piter->__pg_advance = 0; | |
727 | piter->__nents = nents; | |
728 | ||
a321e91b ID |
729 | piter->sg = sglist; |
730 | piter->sg_pgoffset = pgoffset; | |
731 | } | |
732 | EXPORT_SYMBOL(__sg_page_iter_start); | |
733 | ||
734 | static int sg_page_count(struct scatterlist *sg) | |
735 | { | |
736 | return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT; | |
737 | } | |
738 | ||
739 | bool __sg_page_iter_next(struct sg_page_iter *piter) | |
740 | { | |
741 | if (!piter->__nents || !piter->sg) | |
742 | return false; | |
743 | ||
744 | piter->sg_pgoffset += piter->__pg_advance; | |
745 | piter->__pg_advance = 1; | |
746 | ||
747 | while (piter->sg_pgoffset >= sg_page_count(piter->sg)) { | |
748 | piter->sg_pgoffset -= sg_page_count(piter->sg); | |
749 | piter->sg = sg_next(piter->sg); | |
750 | if (!--piter->__nents || !piter->sg) | |
751 | return false; | |
752 | } | |
a321e91b ID |
753 | |
754 | return true; | |
755 | } | |
756 | EXPORT_SYMBOL(__sg_page_iter_next); | |
757 | ||
d901b276 JG |
758 | static int sg_dma_page_count(struct scatterlist *sg) |
759 | { | |
760 | return PAGE_ALIGN(sg->offset + sg_dma_len(sg)) >> PAGE_SHIFT; | |
761 | } | |
762 | ||
763 | bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter) | |
764 | { | |
765 | struct sg_page_iter *piter = &dma_iter->base; | |
766 | ||
767 | if (!piter->__nents || !piter->sg) | |
768 | return false; | |
769 | ||
770 | piter->sg_pgoffset += piter->__pg_advance; | |
771 | piter->__pg_advance = 1; | |
772 | ||
773 | while (piter->sg_pgoffset >= sg_dma_page_count(piter->sg)) { | |
774 | piter->sg_pgoffset -= sg_dma_page_count(piter->sg); | |
775 | piter->sg = sg_next(piter->sg); | |
776 | if (!--piter->__nents || !piter->sg) | |
777 | return false; | |
778 | } | |
779 | ||
780 | return true; | |
781 | } | |
782 | EXPORT_SYMBOL(__sg_page_iter_dma_next); | |
783 | ||
137d3edb TH |
784 | /** |
785 | * sg_miter_start - start mapping iteration over a sg list | |
786 | * @miter: sg mapping iter to be started | |
787 | * @sgl: sg list to iterate over | |
788 | * @nents: number of sg entries | |
789 | * | |
790 | * Description: | |
791 | * Starts mapping iterator @miter. | |
792 | * | |
793 | * Context: | |
794 | * Don't care. | |
795 | */ | |
796 | void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, | |
797 | unsigned int nents, unsigned int flags) | |
798 | { | |
799 | memset(miter, 0, sizeof(struct sg_mapping_iter)); | |
800 | ||
4225fc85 | 801 | __sg_page_iter_start(&miter->piter, sgl, nents, 0); |
6de7e356 | 802 | WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG))); |
137d3edb TH |
803 | miter->__flags = flags; |
804 | } | |
805 | EXPORT_SYMBOL(sg_miter_start); | |
806 | ||
11052004 AM |
807 | static bool sg_miter_get_next_page(struct sg_mapping_iter *miter) |
808 | { | |
809 | if (!miter->__remaining) { | |
810 | struct scatterlist *sg; | |
11052004 AM |
811 | |
812 | if (!__sg_page_iter_next(&miter->piter)) | |
813 | return false; | |
814 | ||
815 | sg = miter->piter.sg; | |
11052004 | 816 | |
aeb87246 CL |
817 | miter->__offset = miter->piter.sg_pgoffset ? 0 : sg->offset; |
818 | miter->piter.sg_pgoffset += miter->__offset >> PAGE_SHIFT; | |
819 | miter->__offset &= PAGE_SIZE - 1; | |
11052004 | 820 | miter->__remaining = sg->offset + sg->length - |
aeb87246 CL |
821 | (miter->piter.sg_pgoffset << PAGE_SHIFT) - |
822 | miter->__offset; | |
11052004 AM |
823 | miter->__remaining = min_t(unsigned long, miter->__remaining, |
824 | PAGE_SIZE - miter->__offset); | |
825 | } | |
826 | ||
827 | return true; | |
828 | } | |
829 | ||
df642cea AM |
830 | /** |
831 | * sg_miter_skip - reposition mapping iterator | |
832 | * @miter: sg mapping iter to be skipped | |
833 | * @offset: number of bytes to plus the current location | |
834 | * | |
835 | * Description: | |
836 | * Sets the offset of @miter to its current location plus @offset bytes. | |
837 | * If mapping iterator @miter has been proceeded by sg_miter_next(), this | |
838 | * stops @miter. | |
839 | * | |
840 | * Context: | |
723aca20 | 841 | * Don't care. |
df642cea AM |
842 | * |
843 | * Returns: | |
844 | * true if @miter contains the valid mapping. false if end of sg | |
845 | * list is reached. | |
846 | */ | |
0d6077f8 | 847 | bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset) |
df642cea AM |
848 | { |
849 | sg_miter_stop(miter); | |
850 | ||
851 | while (offset) { | |
852 | off_t consumed; | |
853 | ||
854 | if (!sg_miter_get_next_page(miter)) | |
855 | return false; | |
856 | ||
857 | consumed = min_t(off_t, offset, miter->__remaining); | |
858 | miter->__offset += consumed; | |
859 | miter->__remaining -= consumed; | |
860 | offset -= consumed; | |
861 | } | |
862 | ||
863 | return true; | |
864 | } | |
0d6077f8 | 865 | EXPORT_SYMBOL(sg_miter_skip); |
df642cea | 866 | |
137d3edb TH |
867 | /** |
868 | * sg_miter_next - proceed mapping iterator to the next mapping | |
869 | * @miter: sg mapping iter to proceed | |
870 | * | |
871 | * Description: | |
8290e2d2 TH |
872 | * Proceeds @miter to the next mapping. @miter should have been started |
873 | * using sg_miter_start(). On successful return, @miter->page, | |
874 | * @miter->addr and @miter->length point to the current mapping. | |
137d3edb TH |
875 | * |
876 | * Context: | |
723aca20 | 877 | * May sleep if !SG_MITER_ATOMIC. |
137d3edb TH |
878 | * |
879 | * Returns: | |
880 | * true if @miter contains the next mapping. false if end of sg | |
881 | * list is reached. | |
882 | */ | |
883 | bool sg_miter_next(struct sg_mapping_iter *miter) | |
884 | { | |
137d3edb TH |
885 | sg_miter_stop(miter); |
886 | ||
4225fc85 ID |
887 | /* |
888 | * Get to the next page if necessary. | |
889 | * __remaining, __offset is adjusted by sg_miter_stop | |
890 | */ | |
11052004 AM |
891 | if (!sg_miter_get_next_page(miter)) |
892 | return false; | |
137d3edb | 893 | |
2db76d7c | 894 | miter->page = sg_page_iter_page(&miter->piter); |
4225fc85 | 895 | miter->consumed = miter->length = miter->__remaining; |
137d3edb TH |
896 | |
897 | if (miter->__flags & SG_MITER_ATOMIC) | |
4225fc85 | 898 | miter->addr = kmap_atomic(miter->page) + miter->__offset; |
137d3edb | 899 | else |
4225fc85 | 900 | miter->addr = kmap(miter->page) + miter->__offset; |
137d3edb TH |
901 | |
902 | return true; | |
903 | } | |
904 | EXPORT_SYMBOL(sg_miter_next); | |
905 | ||
906 | /** | |
907 | * sg_miter_stop - stop mapping iteration | |
908 | * @miter: sg mapping iter to be stopped | |
909 | * | |
910 | * Description: | |
911 | * Stops mapping iterator @miter. @miter should have been started | |
4ba6a2b2 MY |
912 | * using sg_miter_start(). A stopped iteration can be resumed by |
913 | * calling sg_miter_next() on it. This is useful when resources (kmap) | |
914 | * need to be released during iteration. | |
137d3edb TH |
915 | * |
916 | * Context: | |
723aca20 | 917 | * Don't care otherwise. |
137d3edb TH |
918 | */ |
919 | void sg_miter_stop(struct sg_mapping_iter *miter) | |
920 | { | |
921 | WARN_ON(miter->consumed > miter->length); | |
922 | ||
923 | /* drop resources from the last iteration */ | |
924 | if (miter->addr) { | |
925 | miter->__offset += miter->consumed; | |
4225fc85 | 926 | miter->__remaining -= miter->consumed; |
137d3edb | 927 | |
0e84f5db CH |
928 | if (miter->__flags & SG_MITER_TO_SG) |
929 | flush_dcache_page(miter->page); | |
6de7e356 | 930 | |
137d3edb | 931 | if (miter->__flags & SG_MITER_ATOMIC) { |
723aca20 | 932 | WARN_ON_ONCE(!pagefault_disabled()); |
c3eede8e | 933 | kunmap_atomic(miter->addr); |
137d3edb | 934 | } else |
f652c521 | 935 | kunmap(miter->page); |
137d3edb TH |
936 | |
937 | miter->page = NULL; | |
938 | miter->addr = NULL; | |
939 | miter->length = 0; | |
940 | miter->consumed = 0; | |
941 | } | |
942 | } | |
943 | EXPORT_SYMBOL(sg_miter_stop); | |
944 | ||
b1adaf65 FT |
945 | /** |
946 | * sg_copy_buffer - Copy data between a linear buffer and an SG list | |
947 | * @sgl: The SG list | |
948 | * @nents: Number of SG entries | |
949 | * @buf: Where to copy from | |
950 | * @buflen: The number of bytes to copy | |
df642cea AM |
951 | * @skip: Number of bytes to skip before copying |
952 | * @to_buffer: transfer direction (true == from an sg list to a | |
6e853185 | 953 | * buffer, false == from a buffer to an sg list) |
b1adaf65 FT |
954 | * |
955 | * Returns the number of copied bytes. | |
956 | * | |
957 | **/ | |
386ecb12 DG |
958 | size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, |
959 | size_t buflen, off_t skip, bool to_buffer) | |
b1adaf65 | 960 | { |
137d3edb TH |
961 | unsigned int offset = 0; |
962 | struct sg_mapping_iter miter; | |
6de7e356 SAS |
963 | unsigned int sg_flags = SG_MITER_ATOMIC; |
964 | ||
965 | if (to_buffer) | |
966 | sg_flags |= SG_MITER_FROM_SG; | |
967 | else | |
968 | sg_flags |= SG_MITER_TO_SG; | |
137d3edb | 969 | |
6de7e356 | 970 | sg_miter_start(&miter, sgl, nents, sg_flags); |
137d3edb | 971 | |
df642cea | 972 | if (!sg_miter_skip(&miter, skip)) |
1f41be7d | 973 | return 0; |
df642cea | 974 | |
1d5210ef | 975 | while ((offset < buflen) && sg_miter_next(&miter)) { |
137d3edb TH |
976 | unsigned int len; |
977 | ||
978 | len = min(miter.length, buflen - offset); | |
979 | ||
980 | if (to_buffer) | |
981 | memcpy(buf + offset, miter.addr, len); | |
6de7e356 | 982 | else |
137d3edb | 983 | memcpy(miter.addr, buf + offset, len); |
b1adaf65 | 984 | |
137d3edb | 985 | offset += len; |
b1adaf65 FT |
986 | } |
987 | ||
137d3edb TH |
988 | sg_miter_stop(&miter); |
989 | ||
990 | return offset; | |
b1adaf65 | 991 | } |
386ecb12 | 992 | EXPORT_SYMBOL(sg_copy_buffer); |
b1adaf65 FT |
993 | |
994 | /** | |
995 | * sg_copy_from_buffer - Copy from a linear buffer to an SG list | |
996 | * @sgl: The SG list | |
997 | * @nents: Number of SG entries | |
998 | * @buf: Where to copy from | |
999 | * @buflen: The number of bytes to copy | |
1000 | * | |
1001 | * Returns the number of copied bytes. | |
1002 | * | |
1003 | **/ | |
1004 | size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, | |
2a1bf8f9 | 1005 | const void *buf, size_t buflen) |
b1adaf65 | 1006 | { |
2a1bf8f9 | 1007 | return sg_copy_buffer(sgl, nents, (void *)buf, buflen, 0, false); |
b1adaf65 FT |
1008 | } |
1009 | EXPORT_SYMBOL(sg_copy_from_buffer); | |
1010 | ||
1011 | /** | |
1012 | * sg_copy_to_buffer - Copy from an SG list to a linear buffer | |
1013 | * @sgl: The SG list | |
1014 | * @nents: Number of SG entries | |
1015 | * @buf: Where to copy to | |
1016 | * @buflen: The number of bytes to copy | |
1017 | * | |
1018 | * Returns the number of copied bytes. | |
1019 | * | |
1020 | **/ | |
1021 | size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, | |
1022 | void *buf, size_t buflen) | |
1023 | { | |
df642cea | 1024 | return sg_copy_buffer(sgl, nents, buf, buflen, 0, true); |
b1adaf65 FT |
1025 | } |
1026 | EXPORT_SYMBOL(sg_copy_to_buffer); | |
df642cea AM |
1027 | |
1028 | /** | |
1029 | * sg_pcopy_from_buffer - Copy from a linear buffer to an SG list | |
1030 | * @sgl: The SG list | |
1031 | * @nents: Number of SG entries | |
1032 | * @buf: Where to copy from | |
df642cea | 1033 | * @buflen: The number of bytes to copy |
4dc7daf8 | 1034 | * @skip: Number of bytes to skip before copying |
df642cea AM |
1035 | * |
1036 | * Returns the number of copied bytes. | |
1037 | * | |
1038 | **/ | |
1039 | size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, | |
2a1bf8f9 | 1040 | const void *buf, size_t buflen, off_t skip) |
df642cea | 1041 | { |
2a1bf8f9 | 1042 | return sg_copy_buffer(sgl, nents, (void *)buf, buflen, skip, false); |
df642cea AM |
1043 | } |
1044 | EXPORT_SYMBOL(sg_pcopy_from_buffer); | |
1045 | ||
1046 | /** | |
1047 | * sg_pcopy_to_buffer - Copy from an SG list to a linear buffer | |
1048 | * @sgl: The SG list | |
1049 | * @nents: Number of SG entries | |
1050 | * @buf: Where to copy to | |
df642cea | 1051 | * @buflen: The number of bytes to copy |
4dc7daf8 | 1052 | * @skip: Number of bytes to skip before copying |
df642cea AM |
1053 | * |
1054 | * Returns the number of copied bytes. | |
1055 | * | |
1056 | **/ | |
1057 | size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, | |
1058 | void *buf, size_t buflen, off_t skip) | |
1059 | { | |
1060 | return sg_copy_buffer(sgl, nents, buf, buflen, skip, true); | |
1061 | } | |
1062 | EXPORT_SYMBOL(sg_pcopy_to_buffer); | |
0945e569 JT |
1063 | |
1064 | /** | |
1065 | * sg_zero_buffer - Zero-out a part of a SG list | |
1066 | * @sgl: The SG list | |
1067 | * @nents: Number of SG entries | |
1068 | * @buflen: The number of bytes to zero out | |
1069 | * @skip: Number of bytes to skip before zeroing | |
1070 | * | |
1071 | * Returns the number of bytes zeroed. | |
1072 | **/ | |
1073 | size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents, | |
1074 | size_t buflen, off_t skip) | |
1075 | { | |
1076 | unsigned int offset = 0; | |
1077 | struct sg_mapping_iter miter; | |
1078 | unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG; | |
1079 | ||
1080 | sg_miter_start(&miter, sgl, nents, sg_flags); | |
1081 | ||
1082 | if (!sg_miter_skip(&miter, skip)) | |
1083 | return false; | |
1084 | ||
1085 | while (offset < buflen && sg_miter_next(&miter)) { | |
1086 | unsigned int len; | |
1087 | ||
1088 | len = min(miter.length, buflen - offset); | |
1089 | memset(miter.addr, 0, len); | |
1090 | ||
1091 | offset += len; | |
1092 | } | |
1093 | ||
1094 | sg_miter_stop(&miter); | |
1095 | return offset; | |
1096 | } | |
1097 | EXPORT_SYMBOL(sg_zero_buffer); |