2 * Asynchronous RAID-6 recovery calculations ASYNC_TX API.
3 * Copyright(c) 2009 Intel Corporation
5 * based on raid6recov.c:
6 * Copyright 2002 H. Peter Anvin
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)
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
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.
23 #include <linux/kernel.h>
24 #include <linux/interrupt.h>
25 #include <linux/dma-mapping.h>
26 #include <linux/raid/pq.h>
27 #include <linux/async_tx.h>
29 static struct dma_async_tx_descriptor *
30 async_sum_product(struct page *dest, struct page **srcs, unsigned char *coef,
31 size_t len, struct async_submit_ctl *submit)
33 struct dma_chan *chan = async_tx_find_channel(submit, DMA_PQ,
34 &dest, 1, srcs, 2, len);
35 struct dma_device *dma = chan ? chan->device : NULL;
36 const u8 *amul, *bmul;
41 dma_addr_t dma_dest[2];
42 dma_addr_t dma_src[2];
43 struct device *dev = dma->dev;
44 struct dma_async_tx_descriptor *tx;
45 enum dma_ctrl_flags dma_flags = DMA_PREP_PQ_DISABLE_P;
47 if (submit->flags & ASYNC_TX_FENCE)
48 dma_flags |= DMA_PREP_FENCE;
49 dma_dest[1] = dma_map_page(dev, dest, 0, len, DMA_BIDIRECTIONAL);
50 dma_src[0] = dma_map_page(dev, srcs[0], 0, len, DMA_TO_DEVICE);
51 dma_src[1] = dma_map_page(dev, srcs[1], 0, len, DMA_TO_DEVICE);
52 tx = dma->device_prep_dma_pq(chan, dma_dest, dma_src, 2, coef,
55 async_tx_submit(chan, tx, submit);
59 /* could not get a descriptor, unmap and fall through to
60 * the synchronous path
62 dma_unmap_page(dev, dma_dest[1], len, DMA_BIDIRECTIONAL);
63 dma_unmap_page(dev, dma_src[0], len, DMA_TO_DEVICE);
64 dma_unmap_page(dev, dma_src[1], len, DMA_TO_DEVICE);
67 /* run the operation synchronously */
68 async_tx_quiesce(&submit->depend_tx);
69 amul = raid6_gfmul[coef[0]];
70 bmul = raid6_gfmul[coef[1]];
71 a = page_address(srcs[0]);
72 b = page_address(srcs[1]);
73 c = page_address(dest);
84 static struct dma_async_tx_descriptor *
85 async_mult(struct page *dest, struct page *src, u8 coef, size_t len,
86 struct async_submit_ctl *submit)
88 struct dma_chan *chan = async_tx_find_channel(submit, DMA_PQ,
89 &dest, 1, &src, 1, len);
90 struct dma_device *dma = chan ? chan->device : NULL;
91 const u8 *qmul; /* Q multiplier table */
95 dma_addr_t dma_dest[2];
96 dma_addr_t dma_src[1];
97 struct device *dev = dma->dev;
98 struct dma_async_tx_descriptor *tx;
99 enum dma_ctrl_flags dma_flags = DMA_PREP_PQ_DISABLE_P;
101 if (submit->flags & ASYNC_TX_FENCE)
102 dma_flags |= DMA_PREP_FENCE;
103 dma_dest[1] = dma_map_page(dev, dest, 0, len, DMA_BIDIRECTIONAL);
104 dma_src[0] = dma_map_page(dev, src, 0, len, DMA_TO_DEVICE);
105 tx = dma->device_prep_dma_pq(chan, dma_dest, dma_src, 1, &coef,
108 async_tx_submit(chan, tx, submit);
112 /* could not get a descriptor, unmap and fall through to
113 * the synchronous path
115 dma_unmap_page(dev, dma_dest[1], len, DMA_BIDIRECTIONAL);
116 dma_unmap_page(dev, dma_src[0], len, DMA_TO_DEVICE);
119 /* no channel available, or failed to allocate a descriptor, so
120 * perform the operation synchronously
122 async_tx_quiesce(&submit->depend_tx);
123 qmul = raid6_gfmul[coef];
124 d = page_address(dest);
125 s = page_address(src);
133 static struct dma_async_tx_descriptor *
134 __2data_recov_4(size_t bytes, int faila, int failb, struct page **blocks,
135 struct async_submit_ctl *submit)
137 struct dma_async_tx_descriptor *tx = NULL;
138 struct page *p, *q, *a, *b;
139 struct page *srcs[2];
140 unsigned char coef[2];
141 enum async_tx_flags flags = submit->flags;
142 dma_async_tx_callback cb_fn = submit->cb_fn;
143 void *cb_param = submit->cb_param;
144 void *scribble = submit->scribble;
152 /* in the 4 disk case P + Pxy == P and Q + Qxy == Q */
153 /* Dx = A*(P+Pxy) + B*(Q+Qxy) */
156 coef[0] = raid6_gfexi[failb-faila];
157 coef[1] = raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]];
158 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
159 tx = async_sum_product(b, srcs, coef, bytes, submit);
164 init_async_submit(submit, flags | ASYNC_TX_XOR_ZERO_DST, tx, cb_fn,
166 tx = async_xor(a, srcs, 0, 2, bytes, submit);
172 static struct dma_async_tx_descriptor *
173 __2data_recov_5(size_t bytes, int faila, int failb, struct page **blocks,
174 struct async_submit_ctl *submit)
176 struct dma_async_tx_descriptor *tx = NULL;
177 struct page *p, *q, *g, *dp, *dq;
178 struct page *srcs[2];
179 unsigned char coef[2];
180 enum async_tx_flags flags = submit->flags;
181 dma_async_tx_callback cb_fn = submit->cb_fn;
182 void *cb_param = submit->cb_param;
183 void *scribble = submit->scribble;
184 int uninitialized_var(good);
187 for (i = 0; i < 3; i++) {
188 if (i == faila || i == failb)
201 /* Compute syndrome with zero for the missing data pages
202 * Use the dead data pages as temporary storage for delta p and
208 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
209 tx = async_memcpy(dp, g, 0, 0, bytes, submit);
210 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
211 tx = async_mult(dq, g, raid6_gfexp[good], bytes, submit);
213 /* compute P + Pxy */
216 init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
217 NULL, NULL, scribble);
218 tx = async_xor(dp, srcs, 0, 2, bytes, submit);
220 /* compute Q + Qxy */
223 init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
224 NULL, NULL, scribble);
225 tx = async_xor(dq, srcs, 0, 2, bytes, submit);
227 /* Dx = A*(P+Pxy) + B*(Q+Qxy) */
230 coef[0] = raid6_gfexi[failb-faila];
231 coef[1] = raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]];
232 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
233 tx = async_sum_product(dq, srcs, coef, bytes, submit);
238 init_async_submit(submit, flags | ASYNC_TX_XOR_DROP_DST, tx, cb_fn,
240 tx = async_xor(dp, srcs, 0, 2, bytes, submit);
245 static struct dma_async_tx_descriptor *
246 __2data_recov_n(int disks, size_t bytes, int faila, int failb,
247 struct page **blocks, struct async_submit_ctl *submit)
249 struct dma_async_tx_descriptor *tx = NULL;
250 struct page *p, *q, *dp, *dq;
251 struct page *srcs[2];
252 unsigned char coef[2];
253 enum async_tx_flags flags = submit->flags;
254 dma_async_tx_callback cb_fn = submit->cb_fn;
255 void *cb_param = submit->cb_param;
256 void *scribble = submit->scribble;
261 /* Compute syndrome with zero for the missing data pages
262 * Use the dead data pages as temporary storage for
263 * delta p and delta q
266 blocks[faila] = (void *)raid6_empty_zero_page;
267 blocks[disks-2] = dp;
269 blocks[failb] = (void *)raid6_empty_zero_page;
270 blocks[disks-1] = dq;
272 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
273 tx = async_gen_syndrome(blocks, 0, disks, bytes, submit);
275 /* Restore pointer table */
281 /* compute P + Pxy */
284 init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
285 NULL, NULL, scribble);
286 tx = async_xor(dp, srcs, 0, 2, bytes, submit);
288 /* compute Q + Qxy */
291 init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
292 NULL, NULL, scribble);
293 tx = async_xor(dq, srcs, 0, 2, bytes, submit);
295 /* Dx = A*(P+Pxy) + B*(Q+Qxy) */
298 coef[0] = raid6_gfexi[failb-faila];
299 coef[1] = raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]];
300 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
301 tx = async_sum_product(dq, srcs, coef, bytes, submit);
306 init_async_submit(submit, flags | ASYNC_TX_XOR_DROP_DST, tx, cb_fn,
308 tx = async_xor(dp, srcs, 0, 2, bytes, submit);
314 * async_raid6_2data_recov - asynchronously calculate two missing data blocks
315 * @disks: number of disks in the RAID-6 array
317 * @faila: first failed drive index
318 * @failb: second failed drive index
319 * @blocks: array of source pointers where the last two entries are p and q
320 * @submit: submission/completion modifiers
322 struct dma_async_tx_descriptor *
323 async_raid6_2data_recov(int disks, size_t bytes, int faila, int failb,
324 struct page **blocks, struct async_submit_ctl *submit)
326 BUG_ON(faila == failb);
330 pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes);
332 /* we need to preserve the contents of 'blocks' for the async
333 * case, so punt to synchronous if a scribble buffer is not available
335 if (!submit->scribble) {
336 void **ptrs = (void **) blocks;
339 async_tx_quiesce(&submit->depend_tx);
340 for (i = 0; i < disks; i++)
341 ptrs[i] = page_address(blocks[i]);
343 raid6_2data_recov(disks, bytes, faila, failb, ptrs);
345 async_tx_sync_epilog(submit);
352 /* dma devices do not uniformly understand a zero source pq
353 * operation (in contrast to the synchronous case), so
354 * explicitly handle the 4 disk special case
356 return __2data_recov_4(bytes, faila, failb, blocks, submit);
358 /* dma devices do not uniformly understand a single
359 * source pq operation (in contrast to the synchronous
360 * case), so explicitly handle the 5 disk special case
362 return __2data_recov_5(bytes, faila, failb, blocks, submit);
364 return __2data_recov_n(disks, bytes, faila, failb, blocks, submit);
367 EXPORT_SYMBOL_GPL(async_raid6_2data_recov);
370 * async_raid6_datap_recov - asynchronously calculate a data and the 'p' block
371 * @disks: number of disks in the RAID-6 array
373 * @faila: failed drive index
374 * @blocks: array of source pointers where the last two entries are p and q
375 * @submit: submission/completion modifiers
377 struct dma_async_tx_descriptor *
378 async_raid6_datap_recov(int disks, size_t bytes, int faila,
379 struct page **blocks, struct async_submit_ctl *submit)
381 struct dma_async_tx_descriptor *tx = NULL;
382 struct page *p, *q, *dq;
384 enum async_tx_flags flags = submit->flags;
385 dma_async_tx_callback cb_fn = submit->cb_fn;
386 void *cb_param = submit->cb_param;
387 void *scribble = submit->scribble;
388 struct page *srcs[2];
390 pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes);
392 /* we need to preserve the contents of 'blocks' for the async
393 * case, so punt to synchronous if a scribble buffer is not available
396 void **ptrs = (void **) blocks;
399 async_tx_quiesce(&submit->depend_tx);
400 for (i = 0; i < disks; i++)
401 ptrs[i] = page_address(blocks[i]);
403 raid6_datap_recov(disks, bytes, faila, ptrs);
405 async_tx_sync_epilog(submit);
413 /* Compute syndrome with zero for the missing data page
414 * Use the dead data page as temporary storage for delta q
417 blocks[faila] = (void *)raid6_empty_zero_page;
418 blocks[disks-1] = dq;
420 /* in the 4 disk case we only need to perform a single source
424 int good = faila == 0 ? 1 : 0;
425 struct page *g = blocks[good];
427 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL,
429 tx = async_memcpy(p, g, 0, 0, bytes, submit);
431 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL,
433 tx = async_mult(dq, g, raid6_gfexp[good], bytes, submit);
435 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL,
437 tx = async_gen_syndrome(blocks, 0, disks, bytes, submit);
440 /* Restore pointer table */
444 /* calculate g^{-faila} */
445 coef = raid6_gfinv[raid6_gfexp[faila]];
449 init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
450 NULL, NULL, scribble);
451 tx = async_xor(dq, srcs, 0, 2, bytes, submit);
453 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
454 tx = async_mult(dq, dq, coef, bytes, submit);
458 init_async_submit(submit, flags | ASYNC_TX_XOR_DROP_DST, tx, cb_fn,
460 tx = async_xor(p, srcs, 0, 2, bytes, submit);
464 EXPORT_SYMBOL_GPL(async_raid6_datap_recov);
466 MODULE_AUTHOR("Dan Williams <dan.j.williams@intel.com>");
467 MODULE_DESCRIPTION("asynchronous RAID-6 recovery api");
468 MODULE_LICENSE("GPL");