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 * 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 * 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 * 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 * 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 * 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 * 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 * 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