crypto/async_tx/async_raid6_recov.c

   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");