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(size_t bytes, int faila, int failb, struct page **blocks, 135 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[4-2]; 147 q = blocks[4-1]; 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(size_t bytes, int faila, int failb, struct page **blocks, 174 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 uninitialized_var(good); 185 int i; 186 187 for (i = 0; i < 3; i++) { 188 if (i == faila || i == failb) 189 continue; 190 else { 191 good = i; 192 break; 193 } 194 } 195 BUG_ON(i >= 3); 196 197 p = blocks[5-2]; 198 q = blocks[5-1]; 199 g = blocks[good]; 200 201 /* Compute syndrome with zero for the missing data pages 202 * Use the dead data pages as temporary storage for delta p and 203 * delta q 204 */ 205 dp = blocks[faila]; 206 dq = blocks[failb]; 207 208 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); 212 213 /* compute P + Pxy */ 214 srcs[0] = dp; 215 srcs[1] = p; 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); 219 220 /* compute Q + Qxy */ 221 srcs[0] = dq; 222 srcs[1] = q; 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); 226 227 /* Dx = A*(P+Pxy) + B*(Q+Qxy) */ 228 srcs[0] = dp; 229 srcs[1] = dq; 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); 234 235 /* Dy = P+Pxy+Dx */ 236 srcs[0] = dp; 237 srcs[1] = dq; 238 init_async_submit(submit, flags | ASYNC_TX_XOR_DROP_DST, tx, cb_fn, 239 cb_param, scribble); 240 tx = async_xor(dp, srcs, 0, 2, bytes, submit); 241 242 return tx; 243 } 244 245 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) 248 { 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; 257 258 p = blocks[disks-2]; 259 q = blocks[disks-1]; 260 261 /* 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 264 */ 265 dp = blocks[faila]; 266 blocks[faila] = NULL; 267 blocks[disks-2] = dp; 268 dq = blocks[failb]; 269 blocks[failb] = NULL; 270 blocks[disks-1] = dq; 271 272 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble); 273 tx = async_gen_syndrome(blocks, 0, disks, bytes, submit); 274 275 /* Restore pointer table */ 276 blocks[faila] = dp; 277 blocks[failb] = dq; 278 blocks[disks-2] = p; 279 blocks[disks-1] = q; 280 281 /* compute P + Pxy */ 282 srcs[0] = dp; 283 srcs[1] = p; 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); 287 288 /* compute Q + Qxy */ 289 srcs[0] = dq; 290 srcs[1] = q; 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); 294 295 /* Dx = A*(P+Pxy) + B*(Q+Qxy) */ 296 srcs[0] = dp; 297 srcs[1] = dq; 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); 302 303 /* Dy = P+Pxy+Dx */ 304 srcs[0] = dp; 305 srcs[1] = dq; 306 init_async_submit(submit, flags | ASYNC_TX_XOR_DROP_DST, tx, cb_fn, 307 cb_param, scribble); 308 tx = async_xor(dp, srcs, 0, 2, bytes, submit); 309 310 return tx; 311 } 312 313 /** 314 * async_raid6_2data_recov - asynchronously calculate two missing data blocks 315 * @disks: number of disks in the RAID-6 array 316 * @bytes: block size 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 321 */ 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) 325 { 326 BUG_ON(faila == failb); 327 if (failb < faila) 328 swap(faila, failb); 329 330 pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes); 331 332 /* we need to preserve the contents of 'blocks' for the async 333 * case, so punt to synchronous if a scribble buffer is not available 334 */ 335 if (!submit->scribble) { 336 void **ptrs = (void **) blocks; 337 int i; 338 339 async_tx_quiesce(&submit->depend_tx); 340 for (i = 0; i < disks; i++) 341 if (blocks[i] == NULL) 342 ptrs[i] = (void*)raid6_empty_zero_page; 343 else 344 ptrs[i] = page_address(blocks[i]); 345 346 raid6_2data_recov(disks, bytes, faila, failb, ptrs); 347 348 async_tx_sync_epilog(submit); 349 350 return NULL; 351 } 352 353 switch (disks) { 354 case 4: 355 /* dma devices do not uniformly understand a zero source pq 356 * operation (in contrast to the synchronous case), so 357 * explicitly handle the 4 disk special case 358 */ 359 return __2data_recov_4(bytes, faila, failb, blocks, submit); 360 case 5: 361 /* dma devices do not uniformly understand a single 362 * source pq operation (in contrast to the synchronous 363 * case), so explicitly handle the 5 disk special case 364 */ 365 return __2data_recov_5(bytes, faila, failb, blocks, submit); 366 default: 367 return __2data_recov_n(disks, bytes, faila, failb, blocks, submit); 368 } 369 } 370 EXPORT_SYMBOL_GPL(async_raid6_2data_recov); 371 372 /** 373 * async_raid6_datap_recov - asynchronously calculate a data and the 'p' block 374 * @disks: number of disks in the RAID-6 array 375 * @bytes: block size 376 * @faila: failed drive index 377 * @blocks: array of source pointers where the last two entries are p and q 378 * @submit: submission/completion modifiers 379 */ 380 struct dma_async_tx_descriptor * 381 async_raid6_datap_recov(int disks, size_t bytes, int faila, 382 struct page **blocks, struct async_submit_ctl *submit) 383 { 384 struct dma_async_tx_descriptor *tx = NULL; 385 struct page *p, *q, *dq; 386 u8 coef; 387 enum async_tx_flags flags = submit->flags; 388 dma_async_tx_callback cb_fn = submit->cb_fn; 389 void *cb_param = submit->cb_param; 390 void *scribble = submit->scribble; 391 struct page *srcs[2]; 392 393 pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes); 394 395 /* we need to preserve the contents of 'blocks' for the async 396 * case, so punt to synchronous if a scribble buffer is not available 397 */ 398 if (!scribble) { 399 void **ptrs = (void **) blocks; 400 int i; 401 402 async_tx_quiesce(&submit->depend_tx); 403 for (i = 0; i < disks; i++) 404 if (blocks[i] == NULL) 405 ptrs[i] = (void*)raid6_empty_zero_page; 406 else 407 ptrs[i] = page_address(blocks[i]); 408 409 raid6_datap_recov(disks, bytes, faila, ptrs); 410 411 async_tx_sync_epilog(submit); 412 413 return NULL; 414 } 415 416 p = blocks[disks-2]; 417 q = blocks[disks-1]; 418 419 /* Compute syndrome with zero for the missing data page 420 * Use the dead data page as temporary storage for delta q 421 */ 422 dq = blocks[faila]; 423 blocks[faila] = NULL; 424 blocks[disks-1] = dq; 425 426 /* in the 4 disk case we only need to perform a single source 427 * multiplication 428 */ 429 if (disks == 4) { 430 int good = faila == 0 ? 1 : 0; 431 struct page *g = blocks[good]; 432 433 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, 434 scribble); 435 tx = async_memcpy(p, g, 0, 0, bytes, submit); 436 437 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, 438 scribble); 439 tx = async_mult(dq, g, raid6_gfexp[good], bytes, submit); 440 } else { 441 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, 442 scribble); 443 tx = async_gen_syndrome(blocks, 0, disks, bytes, submit); 444 } 445 446 /* Restore pointer table */ 447 blocks[faila] = dq; 448 blocks[disks-1] = q; 449 450 /* calculate g^{-faila} */ 451 coef = raid6_gfinv[raid6_gfexp[faila]]; 452 453 srcs[0] = dq; 454 srcs[1] = q; 455 init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx, 456 NULL, NULL, scribble); 457 tx = async_xor(dq, srcs, 0, 2, bytes, submit); 458 459 init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble); 460 tx = async_mult(dq, dq, coef, bytes, submit); 461 462 srcs[0] = p; 463 srcs[1] = dq; 464 init_async_submit(submit, flags | ASYNC_TX_XOR_DROP_DST, tx, cb_fn, 465 cb_param, scribble); 466 tx = async_xor(p, srcs, 0, 2, bytes, submit); 467 468 return tx; 469 } 470 EXPORT_SYMBOL_GPL(async_raid6_datap_recov); 471 472 MODULE_AUTHOR("Dan Williams <dan.j.williams@intel.com>"); 473 MODULE_DESCRIPTION("asynchronous RAID-6 recovery api"); 474 MODULE_LICENSE("GPL"); 475