1 /*
2 * Asynchronous RAID-6 recovery calculations ASYNC_TX API.
3 * Copyright(c) 2009 Intel Corporation
4 *
5 * based on raid6recov.c:
6 * Copyright 2002 H. Peter Anvin
7 *
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License as published by the Free
10 * Software Foundation; either version 2 of the License, or (at your option)
11 * any later version.
12 *
13 * This program is distributed in the hope that it will be useful, but WITHOUT
14 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
16 * more details.
17 *
18 * You should have received a copy of the GNU General Public License along with
19 * this program; if not, write to the Free Software Foundation, Inc., 51
20 * Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 */
23 #include <linux/kernel.h>
24 #include <linux/interrupt.h>
25 #include <linux/module.h>
26 #include <linux/dma-mapping.h>
27 #include <linux/raid/pq.h>
28 #include <linux/async_tx.h>
29 #include <linux/dmaengine.h>
30
31 static struct dma_async_tx_descriptor *
async_sum_product(struct page * dest,struct page ** srcs,unsigned char * coef,size_t len,struct async_submit_ctl * submit)32 async_sum_product(struct page *dest, struct page **srcs, unsigned char *coef,
33 size_t len, struct async_submit_ctl *submit)
34 {
35 struct dma_chan *chan = async_tx_find_channel(submit, DMA_PQ,
36 &dest, 1, srcs, 2, len);
37 struct dma_device *dma = chan ? chan->device : NULL;
38 struct dmaengine_unmap_data *unmap = NULL;
39 const u8 *amul, *bmul;
40 u8 ax, bx;
41 u8 *a, *b, *c;
42
43 if (dma)
44 unmap = dmaengine_get_unmap_data(dma->dev, 3, GFP_NOWAIT);
45
46 if (unmap) {
47 struct device *dev = dma->dev;
48 dma_addr_t pq[2];
49 struct dma_async_tx_descriptor *tx;
50 enum dma_ctrl_flags dma_flags = DMA_PREP_PQ_DISABLE_P;
51
52 if (submit->flags & ASYNC_TX_FENCE)
53 dma_flags |= DMA_PREP_FENCE;
54 unmap->addr[0] = dma_map_page(dev, srcs[0], 0, len, DMA_TO_DEVICE);
55 unmap->addr[1] = dma_map_page(dev, srcs[1], 0, len, DMA_TO_DEVICE);
56 unmap->to_cnt = 2;
57
58 unmap->addr[2] = dma_map_page(dev, dest, 0, len, DMA_BIDIRECTIONAL);
59 unmap->bidi_cnt = 1;
60 /* engine only looks at Q, but expects it to follow P */
61 pq[1] = unmap->addr[2];
62
63 unmap->len = len;
64 tx = dma->device_prep_dma_pq(chan, pq, unmap->addr, 2, coef,
65 len, dma_flags);
66 if (tx) {
67 dma_set_unmap(tx, unmap);
68 async_tx_submit(chan, tx, submit);
69 dmaengine_unmap_put(unmap);
70 return tx;
71 }
72
73 /* could not get a descriptor, unmap and fall through to
74 * the synchronous path
75 */
76 dmaengine_unmap_put(unmap);
77 }
78
79 /* run the operation synchronously */
80 async_tx_quiesce(&submit->depend_tx);
81 amul = raid6_gfmul[coef[0]];
82 bmul = raid6_gfmul[coef[1]];
83 a = page_address(srcs[0]);
84 b = page_address(srcs[1]);
85 c = page_address(dest);
86
87 while (len--) {
88 ax = amul[*a++];
89 bx = bmul[*b++];
90 *c++ = ax ^ bx;
91 }
92
93 return NULL;
94 }
95
96 static struct dma_async_tx_descriptor *
async_mult(struct page * dest,struct page * src,u8 coef,size_t len,struct async_submit_ctl * submit)97 async_mult(struct page *dest, struct page *src, u8 coef, size_t len,
98 struct async_submit_ctl *submit)
99 {
100 struct dma_chan *chan = async_tx_find_channel(submit, DMA_PQ,
101 &dest, 1, &src, 1, len);
102 struct dma_device *dma = chan ? chan->device : NULL;
103 struct dmaengine_unmap_data *unmap = NULL;
104 const u8 *qmul; /* Q multiplier table */
105 u8 *d, *s;
106
107 if (dma)
108 unmap = dmaengine_get_unmap_data(dma->dev, 3, GFP_NOWAIT);
109
110 if (unmap) {
111 dma_addr_t dma_dest[2];
112 struct device *dev = dma->dev;
113 struct dma_async_tx_descriptor *tx;
114 enum dma_ctrl_flags dma_flags = DMA_PREP_PQ_DISABLE_P;
115
116 if (submit->flags & ASYNC_TX_FENCE)
117 dma_flags |= DMA_PREP_FENCE;
118 unmap->addr[0] = dma_map_page(dev, src, 0, len, DMA_TO_DEVICE);
119 unmap->to_cnt++;
120 unmap->addr[1] = dma_map_page(dev, dest, 0, len, DMA_BIDIRECTIONAL);
121 dma_dest[1] = unmap->addr[1];
122 unmap->bidi_cnt++;
123 unmap->len = len;
124
125 /* this looks funny, but the engine looks for Q at
126 * dma_dest[1] and ignores dma_dest[0] as a dest
127 * due to DMA_PREP_PQ_DISABLE_P
128 */
129 tx = dma->device_prep_dma_pq(chan, dma_dest, unmap->addr,
130 1, &coef, len, dma_flags);
131
132 if (tx) {
133 dma_set_unmap(tx, unmap);
134 dmaengine_unmap_put(unmap);
135 async_tx_submit(chan, tx, submit);
136 return tx;
137 }
138
139 /* could not get a descriptor, unmap and fall through to
140 * the synchronous path
141 */
142 dmaengine_unmap_put(unmap);
143 }
144
145 /* no channel available, or failed to allocate a descriptor, so
146 * perform the operation synchronously
147 */
148 async_tx_quiesce(&submit->depend_tx);
149 qmul = raid6_gfmul[coef];
150 d = page_address(dest);
151 s = page_address(src);
152
153 while (len--)
154 *d++ = qmul[*s++];
155
156 return NULL;
157 }
158
159 static struct dma_async_tx_descriptor *
__2data_recov_4(int disks,size_t bytes,int faila,int failb,struct page ** blocks,struct async_submit_ctl * submit)160 __2data_recov_4(int disks, size_t bytes, int faila, int failb,
161 struct page **blocks, struct async_submit_ctl *submit)
162 {
163 struct dma_async_tx_descriptor *tx = NULL;
164 struct page *p, *q, *a, *b;
165 struct page *srcs[2];
166 unsigned char coef[2];
167 enum async_tx_flags flags = submit->flags;
168 dma_async_tx_callback cb_fn = submit->cb_fn;
169 void *cb_param = submit->cb_param;
170 void *scribble = submit->scribble;
171
172 p = blocks[disks-2];
173 q = blocks[disks-1];
174
175 a = blocks[faila];
176 b = blocks[failb];
177
178 /* in the 4 disk case P + Pxy == P and Q + Qxy == Q */
179 /* Dx = A*(P+Pxy) + B*(Q+Qxy) */
180 srcs[0] = p;
181 srcs[1] = q;
182 coef[0] = raid6_gfexi[failb-faila];
183 coef[1] = raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]];
184 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
185 tx = async_sum_product(b, srcs, coef, bytes, submit);
186
187 /* Dy = P+Pxy+Dx */
188 srcs[0] = p;
189 srcs[1] = b;
190 init_async_submit(submit, flags | ASYNC_TX_XOR_ZERO_DST, tx, cb_fn,
191 cb_param, scribble);
192 tx = async_xor(a, srcs, 0, 2, bytes, submit);
193
194 return tx;
195
196 }
197
198 static struct dma_async_tx_descriptor *
__2data_recov_5(int disks,size_t bytes,int faila,int failb,struct page ** blocks,struct async_submit_ctl * submit)199 __2data_recov_5(int disks, size_t bytes, int faila, int failb,
200 struct page **blocks, struct async_submit_ctl *submit)
201 {
202 struct dma_async_tx_descriptor *tx = NULL;
203 struct page *p, *q, *g, *dp, *dq;
204 struct page *srcs[2];
205 unsigned char coef[2];
206 enum async_tx_flags flags = submit->flags;
207 dma_async_tx_callback cb_fn = submit->cb_fn;
208 void *cb_param = submit->cb_param;
209 void *scribble = submit->scribble;
210 int good_srcs, good, i;
211
212 good_srcs = 0;
213 good = -1;
214 for (i = 0; i < disks-2; i++) {
215 if (blocks[i] == NULL)
216 continue;
217 if (i == faila || i == failb)
218 continue;
219 good = i;
220 good_srcs++;
221 }
222 BUG_ON(good_srcs > 1);
223
224 p = blocks[disks-2];
225 q = blocks[disks-1];
226 g = blocks[good];
227
228 /* Compute syndrome with zero for the missing data pages
229 * Use the dead data pages as temporary storage for delta p and
230 * delta q
231 */
232 dp = blocks[faila];
233 dq = blocks[failb];
234
235 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
236 tx = async_memcpy(dp, g, 0, 0, bytes, submit);
237 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
238 tx = async_mult(dq, g, raid6_gfexp[good], bytes, submit);
239
240 /* compute P + Pxy */
241 srcs[0] = dp;
242 srcs[1] = p;
243 init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
244 NULL, NULL, scribble);
245 tx = async_xor(dp, srcs, 0, 2, bytes, submit);
246
247 /* compute Q + Qxy */
248 srcs[0] = dq;
249 srcs[1] = q;
250 init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
251 NULL, NULL, scribble);
252 tx = async_xor(dq, srcs, 0, 2, bytes, submit);
253
254 /* Dx = A*(P+Pxy) + B*(Q+Qxy) */
255 srcs[0] = dp;
256 srcs[1] = dq;
257 coef[0] = raid6_gfexi[failb-faila];
258 coef[1] = raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]];
259 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
260 tx = async_sum_product(dq, srcs, coef, bytes, submit);
261
262 /* Dy = P+Pxy+Dx */
263 srcs[0] = dp;
264 srcs[1] = dq;
265 init_async_submit(submit, flags | ASYNC_TX_XOR_DROP_DST, tx, cb_fn,
266 cb_param, scribble);
267 tx = async_xor(dp, srcs, 0, 2, bytes, submit);
268
269 return tx;
270 }
271
272 static struct dma_async_tx_descriptor *
__2data_recov_n(int disks,size_t bytes,int faila,int failb,struct page ** blocks,struct async_submit_ctl * submit)273 __2data_recov_n(int disks, size_t bytes, int faila, int failb,
274 struct page **blocks, struct async_submit_ctl *submit)
275 {
276 struct dma_async_tx_descriptor *tx = NULL;
277 struct page *p, *q, *dp, *dq;
278 struct page *srcs[2];
279 unsigned char coef[2];
280 enum async_tx_flags flags = submit->flags;
281 dma_async_tx_callback cb_fn = submit->cb_fn;
282 void *cb_param = submit->cb_param;
283 void *scribble = submit->scribble;
284
285 p = blocks[disks-2];
286 q = blocks[disks-1];
287
288 /* Compute syndrome with zero for the missing data pages
289 * Use the dead data pages as temporary storage for
290 * delta p and delta q
291 */
292 dp = blocks[faila];
293 blocks[faila] = NULL;
294 blocks[disks-2] = dp;
295 dq = blocks[failb];
296 blocks[failb] = NULL;
297 blocks[disks-1] = dq;
298
299 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
300 tx = async_gen_syndrome(blocks, 0, disks, bytes, submit);
301
302 /* Restore pointer table */
303 blocks[faila] = dp;
304 blocks[failb] = dq;
305 blocks[disks-2] = p;
306 blocks[disks-1] = q;
307
308 /* compute P + Pxy */
309 srcs[0] = dp;
310 srcs[1] = p;
311 init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
312 NULL, NULL, scribble);
313 tx = async_xor(dp, srcs, 0, 2, bytes, submit);
314
315 /* compute Q + Qxy */
316 srcs[0] = dq;
317 srcs[1] = q;
318 init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
319 NULL, NULL, scribble);
320 tx = async_xor(dq, srcs, 0, 2, bytes, submit);
321
322 /* Dx = A*(P+Pxy) + B*(Q+Qxy) */
323 srcs[0] = dp;
324 srcs[1] = dq;
325 coef[0] = raid6_gfexi[failb-faila];
326 coef[1] = raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]];
327 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
328 tx = async_sum_product(dq, srcs, coef, bytes, submit);
329
330 /* Dy = P+Pxy+Dx */
331 srcs[0] = dp;
332 srcs[1] = dq;
333 init_async_submit(submit, flags | ASYNC_TX_XOR_DROP_DST, tx, cb_fn,
334 cb_param, scribble);
335 tx = async_xor(dp, srcs, 0, 2, bytes, submit);
336
337 return tx;
338 }
339
340 /**
341 * async_raid6_2data_recov - asynchronously calculate two missing data blocks
342 * @disks: number of disks in the RAID-6 array
343 * @bytes: block size
344 * @faila: first failed drive index
345 * @failb: second failed drive index
346 * @blocks: array of source pointers where the last two entries are p and q
347 * @submit: submission/completion modifiers
348 */
349 struct dma_async_tx_descriptor *
async_raid6_2data_recov(int disks,size_t bytes,int faila,int failb,struct page ** blocks,struct async_submit_ctl * submit)350 async_raid6_2data_recov(int disks, size_t bytes, int faila, int failb,
351 struct page **blocks, struct async_submit_ctl *submit)
352 {
353 void *scribble = submit->scribble;
354 int non_zero_srcs, i;
355
356 BUG_ON(faila == failb);
357 if (failb < faila)
358 swap(faila, failb);
359
360 pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes);
361
362 /* if a dma resource is not available or a scribble buffer is not
363 * available punt to the synchronous path. In the 'dma not
364 * available' case be sure to use the scribble buffer to
365 * preserve the content of 'blocks' as the caller intended.
366 */
367 if (!async_dma_find_channel(DMA_PQ) || !scribble) {
368 void **ptrs = scribble ? scribble : (void **) blocks;
369
370 async_tx_quiesce(&submit->depend_tx);
371 for (i = 0; i < disks; i++)
372 if (blocks[i] == NULL)
373 ptrs[i] = (void *) raid6_empty_zero_page;
374 else
375 ptrs[i] = page_address(blocks[i]);
376
377 raid6_2data_recov(disks, bytes, faila, failb, ptrs);
378
379 async_tx_sync_epilog(submit);
380
381 return NULL;
382 }
383
384 non_zero_srcs = 0;
385 for (i = 0; i < disks-2 && non_zero_srcs < 4; i++)
386 if (blocks[i])
387 non_zero_srcs++;
388 switch (non_zero_srcs) {
389 case 0:
390 case 1:
391 /* There must be at least 2 sources - the failed devices. */
392 BUG();
393
394 case 2:
395 /* dma devices do not uniformly understand a zero source pq
396 * operation (in contrast to the synchronous case), so
397 * explicitly handle the special case of a 4 disk array with
398 * both data disks missing.
399 */
400 return __2data_recov_4(disks, bytes, faila, failb, blocks, submit);
401 case 3:
402 /* dma devices do not uniformly understand a single
403 * source pq operation (in contrast to the synchronous
404 * case), so explicitly handle the special case of a 5 disk
405 * array with 2 of 3 data disks missing.
406 */
407 return __2data_recov_5(disks, bytes, faila, failb, blocks, submit);
408 default:
409 return __2data_recov_n(disks, bytes, faila, failb, blocks, submit);
410 }
411 }
412 EXPORT_SYMBOL_GPL(async_raid6_2data_recov);
413
414 /**
415 * async_raid6_datap_recov - asynchronously calculate a data and the 'p' block
416 * @disks: number of disks in the RAID-6 array
417 * @bytes: block size
418 * @faila: failed drive index
419 * @blocks: array of source pointers where the last two entries are p and q
420 * @submit: submission/completion modifiers
421 */
422 struct dma_async_tx_descriptor *
async_raid6_datap_recov(int disks,size_t bytes,int faila,struct page ** blocks,struct async_submit_ctl * submit)423 async_raid6_datap_recov(int disks, size_t bytes, int faila,
424 struct page **blocks, struct async_submit_ctl *submit)
425 {
426 struct dma_async_tx_descriptor *tx = NULL;
427 struct page *p, *q, *dq;
428 u8 coef;
429 enum async_tx_flags flags = submit->flags;
430 dma_async_tx_callback cb_fn = submit->cb_fn;
431 void *cb_param = submit->cb_param;
432 void *scribble = submit->scribble;
433 int good_srcs, good, i;
434 struct page *srcs[2];
435
436 pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes);
437
438 /* if a dma resource is not available or a scribble buffer is not
439 * available punt to the synchronous path. In the 'dma not
440 * available' case be sure to use the scribble buffer to
441 * preserve the content of 'blocks' as the caller intended.
442 */
443 if (!async_dma_find_channel(DMA_PQ) || !scribble) {
444 void **ptrs = scribble ? scribble : (void **) blocks;
445
446 async_tx_quiesce(&submit->depend_tx);
447 for (i = 0; i < disks; i++)
448 if (blocks[i] == NULL)
449 ptrs[i] = (void*)raid6_empty_zero_page;
450 else
451 ptrs[i] = page_address(blocks[i]);
452
453 raid6_datap_recov(disks, bytes, faila, ptrs);
454
455 async_tx_sync_epilog(submit);
456
457 return NULL;
458 }
459
460 good_srcs = 0;
461 good = -1;
462 for (i = 0; i < disks-2; i++) {
463 if (i == faila)
464 continue;
465 if (blocks[i]) {
466 good = i;
467 good_srcs++;
468 if (good_srcs > 1)
469 break;
470 }
471 }
472 BUG_ON(good_srcs == 0);
473
474 p = blocks[disks-2];
475 q = blocks[disks-1];
476
477 /* Compute syndrome with zero for the missing data page
478 * Use the dead data page as temporary storage for delta q
479 */
480 dq = blocks[faila];
481 blocks[faila] = NULL;
482 blocks[disks-1] = dq;
483
484 /* in the 4-disk case we only need to perform a single source
485 * multiplication with the one good data block.
486 */
487 if (good_srcs == 1) {
488 struct page *g = blocks[good];
489
490 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL,
491 scribble);
492 tx = async_memcpy(p, g, 0, 0, bytes, submit);
493
494 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL,
495 scribble);
496 tx = async_mult(dq, g, raid6_gfexp[good], bytes, submit);
497 } else {
498 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL,
499 scribble);
500 tx = async_gen_syndrome(blocks, 0, disks, bytes, submit);
501 }
502
503 /* Restore pointer table */
504 blocks[faila] = dq;
505 blocks[disks-1] = q;
506
507 /* calculate g^{-faila} */
508 coef = raid6_gfinv[raid6_gfexp[faila]];
509
510 srcs[0] = dq;
511 srcs[1] = q;
512 init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
513 NULL, NULL, scribble);
514 tx = async_xor(dq, srcs, 0, 2, bytes, submit);
515
516 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
517 tx = async_mult(dq, dq, coef, bytes, submit);
518
519 srcs[0] = p;
520 srcs[1] = dq;
521 init_async_submit(submit, flags | ASYNC_TX_XOR_DROP_DST, tx, cb_fn,
522 cb_param, scribble);
523 tx = async_xor(p, srcs, 0, 2, bytes, submit);
524
525 return tx;
526 }
527 EXPORT_SYMBOL_GPL(async_raid6_datap_recov);
528
529 MODULE_AUTHOR("Dan Williams <dan.j.williams@intel.com>");
530 MODULE_DESCRIPTION("asynchronous RAID-6 recovery api");
531 MODULE_LICENSE("GPL");
532