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/dma-mapping.h> 26 #include <linux/raid/pq.h> 27 #include <linux/async_tx.h> 28 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) 32 { 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; 37 u8 ax, bx; 38 u8 *a, *b, *c; 39 40 if (dma) { 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; 46 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, 53 len, dma_flags); 54 if (tx) { 55 async_tx_submit(chan, tx, submit); 56 return tx; 57 } 58 59 /* could not get a descriptor, unmap and fall through to 60 * the synchronous path 61 */ 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); 65 } 66 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); 74 75 while (len--) { 76 ax = amul[*a++]; 77 bx = bmul[*b++]; 78 *c++ = ax ^ bx; 79 } 80 81 return NULL; 82 } 83 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) 87 { 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 */ 92 u8 *d, *s; 93 94 if (dma) { 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; 100 101 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, 106 len, dma_flags); 107 if (tx) { 108 async_tx_submit(chan, tx, submit); 109 return tx; 110 } 111 112 /* could not get a descriptor, unmap and fall through to 113 * the synchronous path 114 */ 115 dma_unmap_page(dev, dma_dest[1], len, DMA_BIDIRECTIONAL); 116 dma_unmap_page(dev, dma_src[0], len, DMA_TO_DEVICE); 117 } 118 119 /* no channel available, or failed to allocate a descriptor, so 120 * perform the operation synchronously 121 */ 122 async_tx_quiesce(&submit->depend_tx); 123 qmul = raid6_gfmul[coef]; 124 d = page_address(dest); 125 s = page_address(src); 126 127 while (len--) 128 *d++ = qmul[*s++]; 129 130 return NULL; 131 } 132 133 static struct dma_async_tx_descriptor * 134 __2data_recov_4(int disks, size_t bytes, int faila, int failb, 135 struct page **blocks, struct async_submit_ctl *submit) 136 { 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; 145 146 p = blocks[disks-2]; 147 q = blocks[disks-1]; 148 149 a = blocks[faila]; 150 b = blocks[failb]; 151 152 /* in the 4 disk case P + Pxy == P and Q + Qxy == Q */ 153 /* Dx = A*(P+Pxy) + B*(Q+Qxy) */ 154 srcs[0] = p; 155 srcs[1] = q; 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); 160 161 /* Dy = P+Pxy+Dx */ 162 srcs[0] = p; 163 srcs[1] = b; 164 init_async_submit(submit, flags | ASYNC_TX_XOR_ZERO_DST, tx, cb_fn, 165 cb_param, scribble); 166 tx = async_xor(a, srcs, 0, 2, bytes, submit); 167 168 return tx; 169 170 } 171 172 static struct dma_async_tx_descriptor * 173 __2data_recov_5(int disks, size_t bytes, int faila, int failb, 174 struct page **blocks, struct async_submit_ctl *submit) 175 { 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 good_srcs, good, i; 185 186 good_srcs = 0; 187 good = -1; 188 for (i = 0; i < disks-2; i++) { 189 if (blocks[i] == NULL) 190 continue; 191 if (i == faila || i == failb) 192 continue; 193 good = i; 194 good_srcs++; 195 } 196 BUG_ON(good_srcs > 1); 197 198 p = blocks[disks-2]; 199 q = blocks[disks-1]; 200 g = blocks[good]; 201 202 /* Compute syndrome with zero for the missing data pages 203 * Use the dead data pages as temporary storage for delta p and 204 * delta q 205 */ 206 dp = blocks[faila]; 207 dq = blocks[failb]; 208 209 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble); 210 tx = async_memcpy(dp, g, 0, 0, bytes, submit); 211 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble); 212 tx = async_mult(dq, g, raid6_gfexp[good], bytes, submit); 213 214 /* compute P + Pxy */ 215 srcs[0] = dp; 216 srcs[1] = p; 217 init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx, 218 NULL, NULL, scribble); 219 tx = async_xor(dp, srcs, 0, 2, bytes, submit); 220 221 /* compute Q + Qxy */ 222 srcs[0] = dq; 223 srcs[1] = q; 224 init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx, 225 NULL, NULL, scribble); 226 tx = async_xor(dq, srcs, 0, 2, bytes, submit); 227 228 /* Dx = A*(P+Pxy) + B*(Q+Qxy) */ 229 srcs[0] = dp; 230 srcs[1] = dq; 231 coef[0] = raid6_gfexi[failb-faila]; 232 coef[1] = raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]]; 233 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble); 234 tx = async_sum_product(dq, srcs, coef, bytes, submit); 235 236 /* Dy = P+Pxy+Dx */ 237 srcs[0] = dp; 238 srcs[1] = dq; 239 init_async_submit(submit, flags | ASYNC_TX_XOR_DROP_DST, tx, cb_fn, 240 cb_param, scribble); 241 tx = async_xor(dp, srcs, 0, 2, bytes, submit); 242 243 return tx; 244 } 245 246 static struct dma_async_tx_descriptor * 247 __2data_recov_n(int disks, size_t bytes, int faila, int failb, 248 struct page **blocks, struct async_submit_ctl *submit) 249 { 250 struct dma_async_tx_descriptor *tx = NULL; 251 struct page *p, *q, *dp, *dq; 252 struct page *srcs[2]; 253 unsigned char coef[2]; 254 enum async_tx_flags flags = submit->flags; 255 dma_async_tx_callback cb_fn = submit->cb_fn; 256 void *cb_param = submit->cb_param; 257 void *scribble = submit->scribble; 258 259 p = blocks[disks-2]; 260 q = blocks[disks-1]; 261 262 /* Compute syndrome with zero for the missing data pages 263 * Use the dead data pages as temporary storage for 264 * delta p and delta q 265 */ 266 dp = blocks[faila]; 267 blocks[faila] = NULL; 268 blocks[disks-2] = dp; 269 dq = blocks[failb]; 270 blocks[failb] = NULL; 271 blocks[disks-1] = dq; 272 273 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble); 274 tx = async_gen_syndrome(blocks, 0, disks, bytes, submit); 275 276 /* Restore pointer table */ 277 blocks[faila] = dp; 278 blocks[failb] = dq; 279 blocks[disks-2] = p; 280 blocks[disks-1] = q; 281 282 /* compute P + Pxy */ 283 srcs[0] = dp; 284 srcs[1] = p; 285 init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx, 286 NULL, NULL, scribble); 287 tx = async_xor(dp, srcs, 0, 2, bytes, submit); 288 289 /* compute Q + Qxy */ 290 srcs[0] = dq; 291 srcs[1] = q; 292 init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx, 293 NULL, NULL, scribble); 294 tx = async_xor(dq, srcs, 0, 2, bytes, submit); 295 296 /* Dx = A*(P+Pxy) + B*(Q+Qxy) */ 297 srcs[0] = dp; 298 srcs[1] = dq; 299 coef[0] = raid6_gfexi[failb-faila]; 300 coef[1] = raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]]; 301 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble); 302 tx = async_sum_product(dq, srcs, coef, bytes, submit); 303 304 /* Dy = P+Pxy+Dx */ 305 srcs[0] = dp; 306 srcs[1] = dq; 307 init_async_submit(submit, flags | ASYNC_TX_XOR_DROP_DST, tx, cb_fn, 308 cb_param, scribble); 309 tx = async_xor(dp, srcs, 0, 2, bytes, submit); 310 311 return tx; 312 } 313 314 /** 315 * async_raid6_2data_recov - asynchronously calculate two missing data blocks 316 * @disks: number of disks in the RAID-6 array 317 * @bytes: block size 318 * @faila: first failed drive index 319 * @failb: second failed drive index 320 * @blocks: array of source pointers where the last two entries are p and q 321 * @submit: submission/completion modifiers 322 */ 323 struct dma_async_tx_descriptor * 324 async_raid6_2data_recov(int disks, size_t bytes, int faila, int failb, 325 struct page **blocks, struct async_submit_ctl *submit) 326 { 327 int non_zero_srcs, i; 328 329 BUG_ON(faila == failb); 330 if (failb < faila) 331 swap(faila, failb); 332 333 pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes); 334 335 /* we need to preserve the contents of 'blocks' for the async 336 * case, so punt to synchronous if a scribble buffer is not available 337 */ 338 if (!submit->scribble) { 339 void **ptrs = (void **) blocks; 340 341 async_tx_quiesce(&submit->depend_tx); 342 for (i = 0; i < disks; i++) 343 if (blocks[i] == NULL) 344 ptrs[i] = (void *) raid6_empty_zero_page; 345 else 346 ptrs[i] = page_address(blocks[i]); 347 348 raid6_2data_recov(disks, bytes, faila, failb, ptrs); 349 350 async_tx_sync_epilog(submit); 351 352 return NULL; 353 } 354 355 non_zero_srcs = 0; 356 for (i = 0; i < disks-2 && non_zero_srcs < 4; i++) 357 if (blocks[i]) 358 non_zero_srcs++; 359 switch (non_zero_srcs) { 360 case 0: 361 case 1: 362 /* There must be at least 2 sources - the failed devices. */ 363 BUG(); 364 365 case 2: 366 /* dma devices do not uniformly understand a zero source pq 367 * operation (in contrast to the synchronous case), so 368 * explicitly handle the special case of a 4 disk array with 369 * both data disks missing. 370 */ 371 return __2data_recov_4(disks, bytes, faila, failb, blocks, submit); 372 case 3: 373 /* dma devices do not uniformly understand a single 374 * source pq operation (in contrast to the synchronous 375 * case), so explicitly handle the special case of a 5 disk 376 * array with 2 of 3 data disks missing. 377 */ 378 return __2data_recov_5(disks, bytes, faila, failb, blocks, submit); 379 default: 380 return __2data_recov_n(disks, bytes, faila, failb, blocks, submit); 381 } 382 } 383 EXPORT_SYMBOL_GPL(async_raid6_2data_recov); 384 385 /** 386 * async_raid6_datap_recov - asynchronously calculate a data and the 'p' block 387 * @disks: number of disks in the RAID-6 array 388 * @bytes: block size 389 * @faila: failed drive index 390 * @blocks: array of source pointers where the last two entries are p and q 391 * @submit: submission/completion modifiers 392 */ 393 struct dma_async_tx_descriptor * 394 async_raid6_datap_recov(int disks, size_t bytes, int faila, 395 struct page **blocks, struct async_submit_ctl *submit) 396 { 397 struct dma_async_tx_descriptor *tx = NULL; 398 struct page *p, *q, *dq; 399 u8 coef; 400 enum async_tx_flags flags = submit->flags; 401 dma_async_tx_callback cb_fn = submit->cb_fn; 402 void *cb_param = submit->cb_param; 403 void *scribble = submit->scribble; 404 int good_srcs, good, i; 405 struct page *srcs[2]; 406 407 pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes); 408 409 /* we need to preserve the contents of 'blocks' for the async 410 * case, so punt to synchronous if a scribble buffer is not available 411 */ 412 if (!scribble) { 413 void **ptrs = (void **) blocks; 414 415 async_tx_quiesce(&submit->depend_tx); 416 for (i = 0; i < disks; i++) 417 if (blocks[i] == NULL) 418 ptrs[i] = (void*)raid6_empty_zero_page; 419 else 420 ptrs[i] = page_address(blocks[i]); 421 422 raid6_datap_recov(disks, bytes, faila, ptrs); 423 424 async_tx_sync_epilog(submit); 425 426 return NULL; 427 } 428 429 good_srcs = 0; 430 good = -1; 431 for (i = 0; i < disks-2; i++) { 432 if (i == faila) 433 continue; 434 if (blocks[i]) { 435 good = i; 436 good_srcs++; 437 if (good_srcs > 1) 438 break; 439 } 440 } 441 BUG_ON(good_srcs == 0); 442 443 p = blocks[disks-2]; 444 q = blocks[disks-1]; 445 446 /* Compute syndrome with zero for the missing data page 447 * Use the dead data page as temporary storage for delta q 448 */ 449 dq = blocks[faila]; 450 blocks[faila] = NULL; 451 blocks[disks-1] = dq; 452 453 /* in the 4-disk case we only need to perform a single source 454 * multiplication with the one good data block. 455 */ 456 if (good_srcs == 1) { 457 struct page *g = blocks[good]; 458 459 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, 460 scribble); 461 tx = async_memcpy(p, g, 0, 0, bytes, submit); 462 463 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, 464 scribble); 465 tx = async_mult(dq, g, raid6_gfexp[good], bytes, submit); 466 } else { 467 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, 468 scribble); 469 tx = async_gen_syndrome(blocks, 0, disks, bytes, submit); 470 } 471 472 /* Restore pointer table */ 473 blocks[faila] = dq; 474 blocks[disks-1] = q; 475 476 /* calculate g^{-faila} */ 477 coef = raid6_gfinv[raid6_gfexp[faila]]; 478 479 srcs[0] = dq; 480 srcs[1] = q; 481 init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx, 482 NULL, NULL, scribble); 483 tx = async_xor(dq, srcs, 0, 2, bytes, submit); 484 485 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble); 486 tx = async_mult(dq, dq, coef, bytes, submit); 487 488 srcs[0] = p; 489 srcs[1] = dq; 490 init_async_submit(submit, flags | ASYNC_TX_XOR_DROP_DST, tx, cb_fn, 491 cb_param, scribble); 492 tx = async_xor(p, srcs, 0, 2, bytes, submit); 493 494 return tx; 495 } 496 EXPORT_SYMBOL_GPL(async_raid6_datap_recov); 497 498 MODULE_AUTHOR("Dan Williams <dan.j.williams@intel.com>"); 499 MODULE_DESCRIPTION("asynchronous RAID-6 recovery api"); 500 MODULE_LICENSE("GPL"); 501