Rev 5056 | Rev 6082 | Go to most recent revision | Details | Compare with Previous | Last modification | View Log | RSS feed
Rev | Author | Line No. | Line |
---|---|---|---|
5056 | serge | 1 | /* |
2 | * Copyright (C) 2007 Jens Axboe |
||
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 | */ |
||
9 | #include |
||
5270 | serge | 10 | #include |
5056 | serge | 11 | #include |
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 | { |
||
25 | #ifdef CONFIG_DEBUG_SG |
||
26 | BUG_ON(sg->sg_magic != SG_MAGIC); |
||
27 | #endif |
||
28 | if (sg_is_last(sg)) |
||
29 | return NULL; |
||
30 | |||
31 | sg++; |
||
32 | if (unlikely(sg_is_chain(sg))) |
||
33 | sg = sg_chain_ptr(sg); |
||
34 | |||
35 | return sg; |
||
36 | } |
||
37 | EXPORT_SYMBOL(sg_next); |
||
38 | |||
39 | /** |
||
40 | * sg_nents - return total count of entries in scatterlist |
||
41 | * @sg: The scatterlist |
||
42 | * |
||
43 | * Description: |
||
44 | * Allows to know how many entries are in sg, taking into acount |
||
45 | * chaining as well |
||
46 | * |
||
47 | **/ |
||
48 | int sg_nents(struct scatterlist *sg) |
||
49 | { |
||
50 | int nents; |
||
51 | for (nents = 0; sg; sg = sg_next(sg)) |
||
52 | nents++; |
||
53 | return nents; |
||
54 | } |
||
55 | EXPORT_SYMBOL(sg_nents); |
||
56 | |||
57 | |||
58 | /** |
||
59 | * sg_last - return the last scatterlist entry in a list |
||
60 | * @sgl: First entry in the scatterlist |
||
61 | * @nents: Number of entries in the scatterlist |
||
62 | * |
||
63 | * Description: |
||
64 | * Should only be used casually, it (currently) scans the entire list |
||
65 | * to get the last entry. |
||
66 | * |
||
67 | * Note that the @sgl@ pointer passed in need not be the first one, |
||
68 | * the important bit is that @nents@ denotes the number of entries that |
||
69 | * exist from @sgl@. |
||
70 | * |
||
71 | **/ |
||
72 | struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents) |
||
73 | { |
||
5270 | serge | 74 | #ifndef CONFIG_ARCH_HAS_SG_CHAIN |
5056 | serge | 75 | struct scatterlist *ret = &sgl[nents - 1]; |
76 | #else |
||
77 | struct scatterlist *sg, *ret = NULL; |
||
78 | unsigned int i; |
||
79 | |||
80 | for_each_sg(sgl, sg, nents, i) |
||
81 | ret = sg; |
||
82 | |||
83 | #endif |
||
84 | #ifdef CONFIG_DEBUG_SG |
||
85 | BUG_ON(sgl[0].sg_magic != SG_MAGIC); |
||
86 | BUG_ON(!sg_is_last(ret)); |
||
87 | #endif |
||
88 | return ret; |
||
89 | } |
||
90 | EXPORT_SYMBOL(sg_last); |
||
91 | |||
92 | /** |
||
93 | * sg_init_table - Initialize SG table |
||
94 | * @sgl: The SG table |
||
95 | * @nents: Number of entries in table |
||
96 | * |
||
97 | * Notes: |
||
98 | * If this is part of a chained sg table, sg_mark_end() should be |
||
99 | * used only on the last table part. |
||
100 | * |
||
101 | **/ |
||
102 | void sg_init_table(struct scatterlist *sgl, unsigned int nents) |
||
103 | { |
||
104 | memset(sgl, 0, sizeof(*sgl) * nents); |
||
105 | #ifdef CONFIG_DEBUG_SG |
||
106 | { |
||
107 | unsigned int i; |
||
108 | for (i = 0; i < nents; i++) |
||
109 | sgl[i].sg_magic = SG_MAGIC; |
||
110 | } |
||
111 | #endif |
||
112 | sg_mark_end(&sgl[nents - 1]); |
||
113 | } |
||
114 | EXPORT_SYMBOL(sg_init_table); |
||
115 | |||
116 | /** |
||
117 | * sg_init_one - Initialize a single entry sg list |
||
118 | * @sg: SG entry |
||
119 | * @buf: Virtual address for IO |
||
120 | * @buflen: IO length |
||
121 | * |
||
122 | **/ |
||
123 | //void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen) |
||
124 | //{ |
||
125 | // sg_init_table(sg, 1); |
||
126 | // sg_set_buf(sg, buf, buflen); |
||
127 | //} |
||
128 | EXPORT_SYMBOL(sg_init_one); |
||
129 | |||
130 | /* |
||
131 | * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree |
||
132 | * helpers. |
||
133 | */ |
||
134 | static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask) |
||
135 | { |
||
136 | return kmalloc(nents * sizeof(struct scatterlist), gfp_mask); |
||
137 | } |
||
138 | |||
139 | static void sg_kfree(struct scatterlist *sg, unsigned int nents) |
||
140 | { |
||
141 | kfree(sg); |
||
142 | } |
||
143 | |||
144 | /** |
||
145 | * __sg_free_table - Free a previously mapped sg table |
||
146 | * @table: The sg table header to use |
||
147 | * @max_ents: The maximum number of entries per single scatterlist |
||
148 | * @skip_first_chunk: don't free the (preallocated) first scatterlist chunk |
||
149 | * @free_fn: Free function |
||
150 | * |
||
151 | * Description: |
||
152 | * Free an sg table previously allocated and setup with |
||
153 | * __sg_alloc_table(). The @max_ents value must be identical to |
||
154 | * that previously used with __sg_alloc_table(). |
||
155 | * |
||
156 | **/ |
||
157 | void __sg_free_table(struct sg_table *table, unsigned int max_ents, |
||
158 | bool skip_first_chunk, sg_free_fn *free_fn) |
||
159 | { |
||
160 | struct scatterlist *sgl, *next; |
||
161 | |||
162 | if (unlikely(!table->sgl)) |
||
163 | return; |
||
164 | |||
165 | sgl = table->sgl; |
||
166 | while (table->orig_nents) { |
||
167 | unsigned int alloc_size = table->orig_nents; |
||
168 | unsigned int sg_size; |
||
169 | |||
170 | /* |
||
171 | * If we have more than max_ents segments left, |
||
172 | * then assign 'next' to the sg table after the current one. |
||
173 | * sg_size is then one less than alloc size, since the last |
||
174 | * element is the chain pointer. |
||
175 | */ |
||
176 | if (alloc_size > max_ents) { |
||
177 | next = sg_chain_ptr(&sgl[max_ents - 1]); |
||
178 | alloc_size = max_ents; |
||
179 | sg_size = alloc_size - 1; |
||
180 | } else { |
||
181 | sg_size = alloc_size; |
||
182 | next = NULL; |
||
183 | } |
||
184 | |||
185 | table->orig_nents -= sg_size; |
||
5270 | serge | 186 | if (skip_first_chunk) |
187 | skip_first_chunk = false; |
||
188 | else |
||
5056 | serge | 189 | free_fn(sgl, alloc_size); |
190 | sgl = next; |
||
191 | } |
||
192 | |||
193 | table->sgl = NULL; |
||
194 | } |
||
195 | EXPORT_SYMBOL(__sg_free_table); |
||
196 | |||
197 | /** |
||
198 | * sg_free_table - Free a previously allocated sg table |
||
199 | * @table: The mapped sg table header |
||
200 | * |
||
201 | **/ |
||
202 | void sg_free_table(struct sg_table *table) |
||
203 | { |
||
204 | __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree); |
||
205 | } |
||
206 | EXPORT_SYMBOL(sg_free_table); |
||
207 | |||
208 | /** |
||
209 | * __sg_alloc_table - Allocate and initialize an sg table with given allocator |
||
210 | * @table: The sg table header to use |
||
211 | * @nents: Number of entries in sg list |
||
212 | * @max_ents: The maximum number of entries the allocator returns per call |
||
213 | * @gfp_mask: GFP allocation mask |
||
214 | * @alloc_fn: Allocator to use |
||
215 | * |
||
216 | * Description: |
||
217 | * This function returns a @table @nents long. The allocator is |
||
218 | * defined to return scatterlist chunks of maximum size @max_ents. |
||
219 | * Thus if @nents is bigger than @max_ents, the scatterlists will be |
||
220 | * chained in units of @max_ents. |
||
221 | * |
||
222 | * Notes: |
||
223 | * If this function returns non-0 (eg failure), the caller must call |
||
224 | * __sg_free_table() to cleanup any leftover allocations. |
||
225 | * |
||
226 | **/ |
||
227 | int __sg_alloc_table(struct sg_table *table, unsigned int nents, |
||
228 | unsigned int max_ents, struct scatterlist *first_chunk, |
||
229 | gfp_t gfp_mask, sg_alloc_fn *alloc_fn) |
||
230 | { |
||
231 | struct scatterlist *sg, *prv; |
||
232 | unsigned int left; |
||
233 | |||
234 | memset(table, 0, sizeof(*table)); |
||
235 | |||
236 | if (nents == 0) |
||
237 | return -EINVAL; |
||
5270 | serge | 238 | #ifndef CONFIG_ARCH_HAS_SG_CHAIN |
5056 | serge | 239 | if (WARN_ON_ONCE(nents > max_ents)) |
240 | return -EINVAL; |
||
241 | #endif |
||
242 | |||
243 | left = nents; |
||
244 | prv = NULL; |
||
245 | do { |
||
246 | unsigned int sg_size, alloc_size = left; |
||
247 | |||
248 | if (alloc_size > max_ents) { |
||
249 | alloc_size = max_ents; |
||
250 | sg_size = alloc_size - 1; |
||
251 | } else |
||
252 | sg_size = alloc_size; |
||
253 | |||
254 | left -= sg_size; |
||
255 | |||
256 | if (first_chunk) { |
||
257 | sg = first_chunk; |
||
258 | first_chunk = NULL; |
||
259 | } else { |
||
260 | sg = alloc_fn(alloc_size, gfp_mask); |
||
261 | } |
||
262 | if (unlikely(!sg)) { |
||
263 | /* |
||
264 | * Adjust entry count to reflect that the last |
||
265 | * entry of the previous table won't be used for |
||
266 | * linkage. Without this, sg_kfree() may get |
||
267 | * confused. |
||
268 | */ |
||
269 | if (prv) |
||
270 | table->nents = ++table->orig_nents; |
||
271 | |||
272 | return -ENOMEM; |
||
273 | } |
||
274 | |||
275 | sg_init_table(sg, alloc_size); |
||
276 | table->nents = table->orig_nents += sg_size; |
||
277 | |||
278 | /* |
||
279 | * If this is the first mapping, assign the sg table header. |
||
280 | * If this is not the first mapping, chain previous part. |
||
281 | */ |
||
282 | if (prv) |
||
283 | sg_chain(prv, max_ents, sg); |
||
284 | else |
||
285 | table->sgl = sg; |
||
286 | |||
287 | /* |
||
288 | * If no more entries after this one, mark the end |
||
289 | */ |
||
290 | if (!left) |
||
291 | sg_mark_end(&sg[sg_size - 1]); |
||
292 | |||
293 | prv = sg; |
||
294 | } while (left); |
||
295 | |||
296 | return 0; |
||
297 | } |
||
298 | EXPORT_SYMBOL(__sg_alloc_table); |
||
299 | |||
300 | /** |
||
301 | * sg_alloc_table - Allocate and initialize an sg table |
||
302 | * @table: The sg table header to use |
||
303 | * @nents: Number of entries in sg list |
||
304 | * @gfp_mask: GFP allocation mask |
||
305 | * |
||
306 | * Description: |
||
307 | * Allocate and initialize an sg table. If @nents@ is larger than |
||
308 | * SG_MAX_SINGLE_ALLOC a chained sg table will be setup. |
||
309 | * |
||
310 | **/ |
||
311 | int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) |
||
312 | { |
||
313 | int ret; |
||
314 | |||
315 | ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC, |
||
316 | NULL, gfp_mask, sg_kmalloc); |
||
317 | if (unlikely(ret)) |
||
318 | __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree); |
||
319 | |||
320 | return ret; |
||
321 | } |
||
322 | EXPORT_SYMBOL(sg_alloc_table); |
||
323 | |||
324 | |||
325 | |||
326 | |||
327 | void __sg_page_iter_start(struct sg_page_iter *piter, |
||
328 | struct scatterlist *sglist, unsigned int nents, |
||
329 | unsigned long pgoffset) |
||
330 | { |
||
331 | piter->__pg_advance = 0; |
||
332 | piter->__nents = nents; |
||
333 | |||
334 | piter->sg = sglist; |
||
335 | piter->sg_pgoffset = pgoffset; |
||
336 | } |
||
337 | EXPORT_SYMBOL(__sg_page_iter_start); |
||
338 | |||
339 | static int sg_page_count(struct scatterlist *sg) |
||
340 | { |
||
341 | return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT; |
||
342 | } |
||
343 | |||
344 | bool __sg_page_iter_next(struct sg_page_iter *piter) |
||
345 | { |
||
346 | if (!piter->__nents || !piter->sg) |
||
347 | return false; |
||
348 | |||
349 | piter->sg_pgoffset += piter->__pg_advance; |
||
350 | piter->__pg_advance = 1; |
||
351 | |||
352 | while (piter->sg_pgoffset >= sg_page_count(piter->sg)) { |
||
353 | piter->sg_pgoffset -= sg_page_count(piter->sg); |
||
354 | piter->sg = sg_next(piter->sg); |
||
355 | if (!--piter->__nents || !piter->sg) |
||
356 | return false; |
||
357 | } |
||
358 | |||
359 | return true; |
||
360 | } |
||
361 | EXPORT_SYMBOL(__sg_page_iter_next);> |
||
362 |