1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2009 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 #include <sys/zfs_context.h> 28 #include <sys/spa.h> 29 #include <sys/vdev_impl.h> 30 #include <sys/zio.h> 31 #include <sys/zio_checksum.h> 32 #include <sys/fs/zfs.h> 33 #include <sys/fm/fs/zfs.h> 34 35 /* 36 * Virtual device vector for RAID-Z. 37 * 38 * This vdev supports single, double, and triple parity. For single parity, 39 * we use a simple XOR of all the data columns. For double or triple parity, 40 * we use a special case of Reed-Solomon coding. This extends the 41 * technique described in "The mathematics of RAID-6" by H. Peter Anvin by 42 * drawing on the system described in "A Tutorial on Reed-Solomon Coding for 43 * Fault-Tolerance in RAID-like Systems" by James S. Plank on which the 44 * former is also based. The latter is designed to provide higher performance 45 * for writes. 46 * 47 * Note that the Plank paper claimed to support arbitrary N+M, but was then 48 * amended six years later identifying a critical flaw that invalidates its 49 * claims. Nevertheless, the technique can be adapted to work for up to 50 * triple parity. For additional parity, the amendment "Note: Correction to 51 * the 1997 Tutorial on Reed-Solomon Coding" by James S. Plank and Ying Ding 52 * is viable, but the additional complexity means that write performance will 53 * suffer. 54 * 55 * All of the methods above operate on a Galois field, defined over the 56 * integers mod 2^N. In our case we choose N=8 for GF(8) so that all elements 57 * can be expressed with a single byte. Briefly, the operations on the 58 * field are defined as follows: 59 * 60 * o addition (+) is represented by a bitwise XOR 61 * o subtraction (-) is therefore identical to addition: A + B = A - B 62 * o multiplication of A by 2 is defined by the following bitwise expression: 63 * (A * 2)_7 = A_6 64 * (A * 2)_6 = A_5 65 * (A * 2)_5 = A_4 66 * (A * 2)_4 = A_3 + A_7 67 * (A * 2)_3 = A_2 + A_7 68 * (A * 2)_2 = A_1 + A_7 69 * (A * 2)_1 = A_0 70 * (A * 2)_0 = A_7 71 * 72 * In C, multiplying by 2 is therefore ((a << 1) ^ ((a & 0x80) ? 0x1d : 0)). 73 * As an aside, this multiplication is derived from the error correcting 74 * primitive polynomial x^8 + x^4 + x^3 + x^2 + 1. 75 * 76 * Observe that any number in the field (except for 0) can be expressed as a 77 * power of 2 -- a generator for the field. We store a table of the powers of 78 * 2 and logs base 2 for quick look ups, and exploit the fact that A * B can 79 * be rewritten as 2^(log_2(A) + log_2(B)) (where '+' is normal addition rather 80 * than field addition). The inverse of a field element A (A^-1) is therefore 81 * A ^ (255 - 1) = A^254. 82 * 83 * The up-to-three parity columns, P, Q, R over several data columns, 84 * D_0, ... D_n-1, can be expressed by field operations: 85 * 86 * P = D_0 + D_1 + ... + D_n-2 + D_n-1 87 * Q = 2^n-1 * D_0 + 2^n-2 * D_1 + ... + 2^1 * D_n-2 + 2^0 * D_n-1 88 * = ((...((D_0) * 2 + D_1) * 2 + ...) * 2 + D_n-2) * 2 + D_n-1 89 * R = 4^n-1 * D_0 + 4^n-2 * D_1 + ... + 4^1 * D_n-2 + 4^0 * D_n-1 90 * = ((...((D_0) * 4 + D_1) * 4 + ...) * 4 + D_n-2) * 4 + D_n-1 91 * 92 * We chose 1, 2, and 4 as our generators because 1 corresponds to the trival 93 * XOR operation, and 2 and 4 can be computed quickly and generate linearly- 94 * independent coefficients. (There are no additional coefficients that have 95 * this property which is why the uncorrected Plank method breaks down.) 96 * 97 * See the reconstruction code below for how P, Q and R can used individually 98 * or in concert to recover missing data columns. 99 */ 100 101 typedef struct raidz_col { 102 uint64_t rc_devidx; /* child device index for I/O */ 103 uint64_t rc_offset; /* device offset */ 104 uint64_t rc_size; /* I/O size */ 105 void *rc_data; /* I/O data */ 106 void *rc_gdata; /* used to store the "good" version */ 107 int rc_error; /* I/O error for this device */ 108 uint8_t rc_tried; /* Did we attempt this I/O column? */ 109 uint8_t rc_skipped; /* Did we skip this I/O column? */ 110 } raidz_col_t; 111 112 typedef struct raidz_map { 113 uint64_t rm_cols; /* Regular column count */ 114 uint64_t rm_scols; /* Count including skipped columns */ 115 uint64_t rm_bigcols; /* Number of oversized columns */ 116 uint64_t rm_asize; /* Actual total I/O size */ 117 uint64_t rm_missingdata; /* Count of missing data devices */ 118 uint64_t rm_missingparity; /* Count of missing parity devices */ 119 uint64_t rm_firstdatacol; /* First data column/parity count */ 120 uint64_t rm_nskip; /* Skipped sectors for padding */ 121 uint64_t rm_skipstart; /* Column index of padding start */ 122 void *rm_datacopy; /* rm_asize-buffer of copied data */ 123 uintptr_t rm_reports; /* # of referencing checksum reports */ 124 uint8_t rm_freed; /* map no longer has referencing ZIO */ 125 uint8_t rm_ecksuminjected; /* checksum error was injected */ 126 raidz_col_t rm_col[1]; /* Flexible array of I/O columns */ 127 } raidz_map_t; 128 129 #define VDEV_RAIDZ_P 0 130 #define VDEV_RAIDZ_Q 1 131 #define VDEV_RAIDZ_R 2 132 133 #define VDEV_RAIDZ_MUL_2(x) (((x) << 1) ^ (((x) & 0x80) ? 0x1d : 0)) 134 #define VDEV_RAIDZ_MUL_4(x) (VDEV_RAIDZ_MUL_2(VDEV_RAIDZ_MUL_2(x))) 135 136 /* 137 * We provide a mechanism to perform the field multiplication operation on a 138 * 64-bit value all at once rather than a byte at a time. This works by 139 * creating a mask from the top bit in each byte and using that to 140 * conditionally apply the XOR of 0x1d. 141 */ 142 #define VDEV_RAIDZ_64MUL_2(x, mask) \ 143 { \ 144 (mask) = (x) & 0x8080808080808080ULL; \ 145 (mask) = ((mask) << 1) - ((mask) >> 7); \ 146 (x) = (((x) << 1) & 0xfefefefefefefefeULL) ^ \ 147 ((mask) & 0x1d1d1d1d1d1d1d1d); \ 148 } 149 150 #define VDEV_RAIDZ_64MUL_4(x, mask) \ 151 { \ 152 VDEV_RAIDZ_64MUL_2((x), mask); \ 153 VDEV_RAIDZ_64MUL_2((x), mask); \ 154 } 155 156 /* 157 * Force reconstruction to use the general purpose method. 158 */ 159 int vdev_raidz_default_to_general; 160 161 /* 162 * These two tables represent powers and logs of 2 in the Galois field defined 163 * above. These values were computed by repeatedly multiplying by 2 as above. 164 */ 165 static const uint8_t vdev_raidz_pow2[256] = { 166 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 167 0x1d, 0x3a, 0x74, 0xe8, 0xcd, 0x87, 0x13, 0x26, 168 0x4c, 0x98, 0x2d, 0x5a, 0xb4, 0x75, 0xea, 0xc9, 169 0x8f, 0x03, 0x06, 0x0c, 0x18, 0x30, 0x60, 0xc0, 170 0x9d, 0x27, 0x4e, 0x9c, 0x25, 0x4a, 0x94, 0x35, 171 0x6a, 0xd4, 0xb5, 0x77, 0xee, 0xc1, 0x9f, 0x23, 172 0x46, 0x8c, 0x05, 0x0a, 0x14, 0x28, 0x50, 0xa0, 173 0x5d, 0xba, 0x69, 0xd2, 0xb9, 0x6f, 0xde, 0xa1, 174 0x5f, 0xbe, 0x61, 0xc2, 0x99, 0x2f, 0x5e, 0xbc, 175 0x65, 0xca, 0x89, 0x0f, 0x1e, 0x3c, 0x78, 0xf0, 176 0xfd, 0xe7, 0xd3, 0xbb, 0x6b, 0xd6, 0xb1, 0x7f, 177 0xfe, 0xe1, 0xdf, 0xa3, 0x5b, 0xb6, 0x71, 0xe2, 178 0xd9, 0xaf, 0x43, 0x86, 0x11, 0x22, 0x44, 0x88, 179 0x0d, 0x1a, 0x34, 0x68, 0xd0, 0xbd, 0x67, 0xce, 180 0x81, 0x1f, 0x3e, 0x7c, 0xf8, 0xed, 0xc7, 0x93, 181 0x3b, 0x76, 0xec, 0xc5, 0x97, 0x33, 0x66, 0xcc, 182 0x85, 0x17, 0x2e, 0x5c, 0xb8, 0x6d, 0xda, 0xa9, 183 0x4f, 0x9e, 0x21, 0x42, 0x84, 0x15, 0x2a, 0x54, 184 0xa8, 0x4d, 0x9a, 0x29, 0x52, 0xa4, 0x55, 0xaa, 185 0x49, 0x92, 0x39, 0x72, 0xe4, 0xd5, 0xb7, 0x73, 186 0xe6, 0xd1, 0xbf, 0x63, 0xc6, 0x91, 0x3f, 0x7e, 187 0xfc, 0xe5, 0xd7, 0xb3, 0x7b, 0xf6, 0xf1, 0xff, 188 0xe3, 0xdb, 0xab, 0x4b, 0x96, 0x31, 0x62, 0xc4, 189 0x95, 0x37, 0x6e, 0xdc, 0xa5, 0x57, 0xae, 0x41, 190 0x82, 0x19, 0x32, 0x64, 0xc8, 0x8d, 0x07, 0x0e, 191 0x1c, 0x38, 0x70, 0xe0, 0xdd, 0xa7, 0x53, 0xa6, 192 0x51, 0xa2, 0x59, 0xb2, 0x79, 0xf2, 0xf9, 0xef, 193 0xc3, 0x9b, 0x2b, 0x56, 0xac, 0x45, 0x8a, 0x09, 194 0x12, 0x24, 0x48, 0x90, 0x3d, 0x7a, 0xf4, 0xf5, 195 0xf7, 0xf3, 0xfb, 0xeb, 0xcb, 0x8b, 0x0b, 0x16, 196 0x2c, 0x58, 0xb0, 0x7d, 0xfa, 0xe9, 0xcf, 0x83, 197 0x1b, 0x36, 0x6c, 0xd8, 0xad, 0x47, 0x8e, 0x01 198 }; 199 static const uint8_t vdev_raidz_log2[256] = { 200 0x00, 0x00, 0x01, 0x19, 0x02, 0x32, 0x1a, 0xc6, 201 0x03, 0xdf, 0x33, 0xee, 0x1b, 0x68, 0xc7, 0x4b, 202 0x04, 0x64, 0xe0, 0x0e, 0x34, 0x8d, 0xef, 0x81, 203 0x1c, 0xc1, 0x69, 0xf8, 0xc8, 0x08, 0x4c, 0x71, 204 0x05, 0x8a, 0x65, 0x2f, 0xe1, 0x24, 0x0f, 0x21, 205 0x35, 0x93, 0x8e, 0xda, 0xf0, 0x12, 0x82, 0x45, 206 0x1d, 0xb5, 0xc2, 0x7d, 0x6a, 0x27, 0xf9, 0xb9, 207 0xc9, 0x9a, 0x09, 0x78, 0x4d, 0xe4, 0x72, 0xa6, 208 0x06, 0xbf, 0x8b, 0x62, 0x66, 0xdd, 0x30, 0xfd, 209 0xe2, 0x98, 0x25, 0xb3, 0x10, 0x91, 0x22, 0x88, 210 0x36, 0xd0, 0x94, 0xce, 0x8f, 0x96, 0xdb, 0xbd, 211 0xf1, 0xd2, 0x13, 0x5c, 0x83, 0x38, 0x46, 0x40, 212 0x1e, 0x42, 0xb6, 0xa3, 0xc3, 0x48, 0x7e, 0x6e, 213 0x6b, 0x3a, 0x28, 0x54, 0xfa, 0x85, 0xba, 0x3d, 214 0xca, 0x5e, 0x9b, 0x9f, 0x0a, 0x15, 0x79, 0x2b, 215 0x4e, 0xd4, 0xe5, 0xac, 0x73, 0xf3, 0xa7, 0x57, 216 0x07, 0x70, 0xc0, 0xf7, 0x8c, 0x80, 0x63, 0x0d, 217 0x67, 0x4a, 0xde, 0xed, 0x31, 0xc5, 0xfe, 0x18, 218 0xe3, 0xa5, 0x99, 0x77, 0x26, 0xb8, 0xb4, 0x7c, 219 0x11, 0x44, 0x92, 0xd9, 0x23, 0x20, 0x89, 0x2e, 220 0x37, 0x3f, 0xd1, 0x5b, 0x95, 0xbc, 0xcf, 0xcd, 221 0x90, 0x87, 0x97, 0xb2, 0xdc, 0xfc, 0xbe, 0x61, 222 0xf2, 0x56, 0xd3, 0xab, 0x14, 0x2a, 0x5d, 0x9e, 223 0x84, 0x3c, 0x39, 0x53, 0x47, 0x6d, 0x41, 0xa2, 224 0x1f, 0x2d, 0x43, 0xd8, 0xb7, 0x7b, 0xa4, 0x76, 225 0xc4, 0x17, 0x49, 0xec, 0x7f, 0x0c, 0x6f, 0xf6, 226 0x6c, 0xa1, 0x3b, 0x52, 0x29, 0x9d, 0x55, 0xaa, 227 0xfb, 0x60, 0x86, 0xb1, 0xbb, 0xcc, 0x3e, 0x5a, 228 0xcb, 0x59, 0x5f, 0xb0, 0x9c, 0xa9, 0xa0, 0x51, 229 0x0b, 0xf5, 0x16, 0xeb, 0x7a, 0x75, 0x2c, 0xd7, 230 0x4f, 0xae, 0xd5, 0xe9, 0xe6, 0xe7, 0xad, 0xe8, 231 0x74, 0xd6, 0xf4, 0xea, 0xa8, 0x50, 0x58, 0xaf, 232 }; 233 234 static void vdev_raidz_generate_parity(raidz_map_t *rm); 235 236 /* 237 * Multiply a given number by 2 raised to the given power. 238 */ 239 static uint8_t 240 vdev_raidz_exp2(uint_t a, int exp) 241 { 242 if (a == 0) 243 return (0); 244 245 ASSERT(exp >= 0); 246 ASSERT(vdev_raidz_log2[a] > 0 || a == 1); 247 248 exp += vdev_raidz_log2[a]; 249 if (exp > 255) 250 exp -= 255; 251 252 return (vdev_raidz_pow2[exp]); 253 } 254 255 static void 256 vdev_raidz_map_free(raidz_map_t *rm) 257 { 258 int c; 259 size_t size; 260 261 for (c = 0; c < rm->rm_firstdatacol; c++) { 262 zio_buf_free(rm->rm_col[c].rc_data, rm->rm_col[c].rc_size); 263 264 if (rm->rm_col[c].rc_gdata != NULL) 265 zio_buf_free(rm->rm_col[c].rc_gdata, 266 rm->rm_col[c].rc_size); 267 } 268 269 size = 0; 270 for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) 271 size += rm->rm_col[c].rc_size; 272 273 if (rm->rm_datacopy != NULL) 274 zio_buf_free(rm->rm_datacopy, size); 275 276 kmem_free(rm, offsetof(raidz_map_t, rm_col[rm->rm_scols])); 277 } 278 279 static void 280 vdev_raidz_map_free_vsd(zio_t *zio) 281 { 282 raidz_map_t *rm = zio->io_vsd; 283 284 ASSERT3U(rm->rm_freed, ==, 0); 285 rm->rm_freed = 1; 286 287 if (rm->rm_reports == 0) 288 vdev_raidz_map_free(rm); 289 } 290 291 /*ARGSUSED*/ 292 static void 293 vdev_raidz_cksum_free(void *arg, size_t ignored) 294 { 295 raidz_map_t *rm = arg; 296 297 ASSERT3U(rm->rm_reports, >, 0); 298 299 if (--rm->rm_reports == 0 && rm->rm_freed != 0) 300 vdev_raidz_map_free(rm); 301 } 302 303 static void 304 vdev_raidz_cksum_finish(zio_cksum_report_t *zcr, const void *good_data) 305 { 306 raidz_map_t *rm = zcr->zcr_cbdata; 307 size_t c = zcr->zcr_cbinfo; 308 size_t x; 309 310 const char *good = NULL; 311 const char *bad = rm->rm_col[c].rc_data; 312 313 if (good_data == NULL) { 314 zfs_ereport_finish_checksum(zcr, NULL, NULL, B_FALSE); 315 return; 316 } 317 318 if (c < rm->rm_firstdatacol) { 319 /* 320 * The first time through, calculate the parity blocks for 321 * the good data (this relies on the fact that the good 322 * data never changes for a given logical ZIO) 323 */ 324 if (rm->rm_col[0].rc_gdata == NULL) { 325 char *bad_parity[VDEV_RAIDZ_MAXPARITY]; 326 char *buf; 327 328 /* 329 * Set up the rm_col[]s to generate the parity for 330 * good_data, first saving the parity bufs and 331 * replacing them with buffers to hold the result. 332 */ 333 for (x = 0; x < rm->rm_firstdatacol; x++) { 334 bad_parity[x] = rm->rm_col[x].rc_data; 335 rm->rm_col[x].rc_data = rm->rm_col[x].rc_gdata = 336 zio_buf_alloc(rm->rm_col[x].rc_size); 337 } 338 339 /* fill in the data columns from good_data */ 340 buf = (char *)good_data; 341 for (; x < rm->rm_cols; x++) { 342 rm->rm_col[x].rc_data = buf; 343 buf += rm->rm_col[x].rc_size; 344 } 345 346 /* 347 * Construct the parity from the good data. 348 */ 349 vdev_raidz_generate_parity(rm); 350 351 /* restore everything back to its original state */ 352 for (x = 0; x < rm->rm_firstdatacol; x++) 353 rm->rm_col[x].rc_data = bad_parity[x]; 354 355 buf = rm->rm_datacopy; 356 for (x = rm->rm_firstdatacol; x < rm->rm_cols; x++) { 357 rm->rm_col[x].rc_data = buf; 358 buf += rm->rm_col[x].rc_size; 359 } 360 } 361 362 ASSERT3P(rm->rm_col[c].rc_gdata, !=, NULL); 363 good = rm->rm_col[c].rc_gdata; 364 } else { 365 /* adjust good_data to point at the start of our column */ 366 good = good_data; 367 368 for (x = rm->rm_firstdatacol; x < c; x++) 369 good += rm->rm_col[x].rc_size; 370 } 371 372 /* we drop the ereport if it ends up that the data was good */ 373 zfs_ereport_finish_checksum(zcr, good, bad, B_TRUE); 374 } 375 376 /* 377 * Invoked indirectly by zfs_ereport_start_checksum(), called 378 * below when our read operation fails completely. The main point 379 * is to keep a copy of everything we read from disk, so that at 380 * vdev_raidz_cksum_finish() time we can compare it with the good data. 381 */ 382 static void 383 vdev_raidz_cksum_report(zio_t *zio, zio_cksum_report_t *zcr, void *arg) 384 { 385 size_t c = (size_t)(uintptr_t)arg; 386 caddr_t buf; 387 388 raidz_map_t *rm = zio->io_vsd; 389 size_t size; 390 391 /* set up the report and bump the refcount */ 392 zcr->zcr_cbdata = rm; 393 zcr->zcr_cbinfo = c; 394 zcr->zcr_finish = vdev_raidz_cksum_finish; 395 zcr->zcr_free = vdev_raidz_cksum_free; 396 397 rm->rm_reports++; 398 ASSERT3U(rm->rm_reports, >, 0); 399 400 if (rm->rm_datacopy != NULL) 401 return; 402 403 /* 404 * It's the first time we're called for this raidz_map_t, so we need 405 * to copy the data aside; there's no guarantee that our zio's buffer 406 * won't be re-used for something else. 407 * 408 * Our parity data is already in separate buffers, so there's no need 409 * to copy them. 410 */ 411 412 size = 0; 413 for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) 414 size += rm->rm_col[c].rc_size; 415 416 buf = rm->rm_datacopy = zio_buf_alloc(size); 417 418 for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { 419 raidz_col_t *col = &rm->rm_col[c]; 420 421 bcopy(col->rc_data, buf, col->rc_size); 422 col->rc_data = buf; 423 424 buf += col->rc_size; 425 } 426 ASSERT3P(buf - (caddr_t)rm->rm_datacopy, ==, size); 427 } 428 429 static const zio_vsd_ops_t vdev_raidz_vsd_ops = { 430 vdev_raidz_map_free_vsd, 431 vdev_raidz_cksum_report 432 }; 433 434 static raidz_map_t * 435 vdev_raidz_map_alloc(zio_t *zio, uint64_t unit_shift, uint64_t dcols, 436 uint64_t nparity) 437 { 438 raidz_map_t *rm; 439 uint64_t b = zio->io_offset >> unit_shift; 440 uint64_t s = zio->io_size >> unit_shift; 441 uint64_t f = b % dcols; 442 uint64_t o = (b / dcols) << unit_shift; 443 uint64_t q, r, c, bc, col, acols, scols, coff, devidx, asize, tot; 444 445 q = s / (dcols - nparity); 446 r = s - q * (dcols - nparity); 447 bc = (r == 0 ? 0 : r + nparity); 448 tot = s + nparity * (q + (r == 0 ? 0 : 1)); 449 450 if (q == 0) { 451 acols = bc; 452 scols = MIN(dcols, roundup(bc, nparity + 1)); 453 } else { 454 acols = dcols; 455 scols = dcols; 456 } 457 458 ASSERT3U(acols, <=, scols); 459 460 rm = kmem_alloc(offsetof(raidz_map_t, rm_col[scols]), KM_SLEEP); 461 462 rm->rm_cols = acols; 463 rm->rm_scols = scols; 464 rm->rm_bigcols = bc; 465 rm->rm_skipstart = bc; 466 rm->rm_missingdata = 0; 467 rm->rm_missingparity = 0; 468 rm->rm_firstdatacol = nparity; 469 rm->rm_datacopy = NULL; 470 rm->rm_reports = 0; 471 rm->rm_freed = 0; 472 rm->rm_ecksuminjected = 0; 473 474 asize = 0; 475 476 for (c = 0; c < scols; c++) { 477 col = f + c; 478 coff = o; 479 if (col >= dcols) { 480 col -= dcols; 481 coff += 1ULL << unit_shift; 482 } 483 rm->rm_col[c].rc_devidx = col; 484 rm->rm_col[c].rc_offset = coff; 485 rm->rm_col[c].rc_data = NULL; 486 rm->rm_col[c].rc_gdata = NULL; 487 rm->rm_col[c].rc_error = 0; 488 rm->rm_col[c].rc_tried = 0; 489 rm->rm_col[c].rc_skipped = 0; 490 491 if (c >= acols) 492 rm->rm_col[c].rc_size = 0; 493 else if (c < bc) 494 rm->rm_col[c].rc_size = (q + 1) << unit_shift; 495 else 496 rm->rm_col[c].rc_size = q << unit_shift; 497 498 asize += rm->rm_col[c].rc_size; 499 } 500 501 ASSERT3U(asize, ==, tot << unit_shift); 502 rm->rm_asize = roundup(asize, (nparity + 1) << unit_shift); 503 rm->rm_nskip = roundup(tot, nparity + 1) - tot; 504 ASSERT3U(rm->rm_asize - asize, ==, rm->rm_nskip << unit_shift); 505 ASSERT3U(rm->rm_nskip, <=, nparity); 506 507 for (c = 0; c < rm->rm_firstdatacol; c++) 508 rm->rm_col[c].rc_data = zio_buf_alloc(rm->rm_col[c].rc_size); 509 510 rm->rm_col[c].rc_data = zio->io_data; 511 512 for (c = c + 1; c < acols; c++) 513 rm->rm_col[c].rc_data = (char *)rm->rm_col[c - 1].rc_data + 514 rm->rm_col[c - 1].rc_size; 515 516 /* 517 * If all data stored spans all columns, there's a danger that parity 518 * will always be on the same device and, since parity isn't read 519 * during normal operation, that that device's I/O bandwidth won't be 520 * used effectively. We therefore switch the parity every 1MB. 521 * 522 * ... at least that was, ostensibly, the theory. As a practical 523 * matter unless we juggle the parity between all devices evenly, we 524 * won't see any benefit. Further, occasional writes that aren't a 525 * multiple of the LCM of the number of children and the minimum 526 * stripe width are sufficient to avoid pessimal behavior. 527 * Unfortunately, this decision created an implicit on-disk format 528 * requirement that we need to support for all eternity, but only 529 * for single-parity RAID-Z. 530 * 531 * If we intend to skip a sector in the zeroth column for padding 532 * we must make sure to note this swap. We will never intend to 533 * skip the first column since at least one data and one parity 534 * column must appear in each row. 535 */ 536 ASSERT(rm->rm_cols >= 2); 537 ASSERT(rm->rm_col[0].rc_size == rm->rm_col[1].rc_size); 538 539 if (rm->rm_firstdatacol == 1 && (zio->io_offset & (1ULL << 20))) { 540 devidx = rm->rm_col[0].rc_devidx; 541 o = rm->rm_col[0].rc_offset; 542 rm->rm_col[0].rc_devidx = rm->rm_col[1].rc_devidx; 543 rm->rm_col[0].rc_offset = rm->rm_col[1].rc_offset; 544 rm->rm_col[1].rc_devidx = devidx; 545 rm->rm_col[1].rc_offset = o; 546 547 if (rm->rm_skipstart == 0) 548 rm->rm_skipstart = 1; 549 } 550 551 zio->io_vsd = rm; 552 zio->io_vsd_ops = &vdev_raidz_vsd_ops; 553 return (rm); 554 } 555 556 static void 557 vdev_raidz_generate_parity_p(raidz_map_t *rm) 558 { 559 uint64_t *p, *src, pcount, ccount, i; 560 int c; 561 562 pcount = rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (src[0]); 563 564 for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { 565 src = rm->rm_col[c].rc_data; 566 p = rm->rm_col[VDEV_RAIDZ_P].rc_data; 567 ccount = rm->rm_col[c].rc_size / sizeof (src[0]); 568 569 if (c == rm->rm_firstdatacol) { 570 ASSERT(ccount == pcount); 571 for (i = 0; i < ccount; i++, src++, p++) { 572 *p = *src; 573 } 574 } else { 575 ASSERT(ccount <= pcount); 576 for (i = 0; i < ccount; i++, src++, p++) { 577 *p ^= *src; 578 } 579 } 580 } 581 } 582 583 static void 584 vdev_raidz_generate_parity_pq(raidz_map_t *rm) 585 { 586 uint64_t *p, *q, *src, pcnt, ccnt, mask, i; 587 int c; 588 589 pcnt = rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (src[0]); 590 ASSERT(rm->rm_col[VDEV_RAIDZ_P].rc_size == 591 rm->rm_col[VDEV_RAIDZ_Q].rc_size); 592 593 for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { 594 src = rm->rm_col[c].rc_data; 595 p = rm->rm_col[VDEV_RAIDZ_P].rc_data; 596 q = rm->rm_col[VDEV_RAIDZ_Q].rc_data; 597 598 ccnt = rm->rm_col[c].rc_size / sizeof (src[0]); 599 600 if (c == rm->rm_firstdatacol) { 601 ASSERT(ccnt == pcnt || ccnt == 0); 602 for (i = 0; i < ccnt; i++, src++, p++, q++) { 603 *p = *src; 604 *q = *src; 605 } 606 for (; i < pcnt; i++, src++, p++, q++) { 607 *p = 0; 608 *q = 0; 609 } 610 } else { 611 ASSERT(ccnt <= pcnt); 612 613 /* 614 * Apply the algorithm described above by multiplying 615 * the previous result and adding in the new value. 616 */ 617 for (i = 0; i < ccnt; i++, src++, p++, q++) { 618 *p ^= *src; 619 620 VDEV_RAIDZ_64MUL_2(*q, mask); 621 *q ^= *src; 622 } 623 624 /* 625 * Treat short columns as though they are full of 0s. 626 * Note that there's therefore nothing needed for P. 627 */ 628 for (; i < pcnt; i++, q++) { 629 VDEV_RAIDZ_64MUL_2(*q, mask); 630 } 631 } 632 } 633 } 634 635 static void 636 vdev_raidz_generate_parity_pqr(raidz_map_t *rm) 637 { 638 uint64_t *p, *q, *r, *src, pcnt, ccnt, mask, i; 639 int c; 640 641 pcnt = rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (src[0]); 642 ASSERT(rm->rm_col[VDEV_RAIDZ_P].rc_size == 643 rm->rm_col[VDEV_RAIDZ_Q].rc_size); 644 ASSERT(rm->rm_col[VDEV_RAIDZ_P].rc_size == 645 rm->rm_col[VDEV_RAIDZ_R].rc_size); 646 647 for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { 648 src = rm->rm_col[c].rc_data; 649 p = rm->rm_col[VDEV_RAIDZ_P].rc_data; 650 q = rm->rm_col[VDEV_RAIDZ_Q].rc_data; 651 r = rm->rm_col[VDEV_RAIDZ_R].rc_data; 652 653 ccnt = rm->rm_col[c].rc_size / sizeof (src[0]); 654 655 if (c == rm->rm_firstdatacol) { 656 ASSERT(ccnt == pcnt || ccnt == 0); 657 for (i = 0; i < ccnt; i++, src++, p++, q++, r++) { 658 *p = *src; 659 *q = *src; 660 *r = *src; 661 } 662 for (; i < pcnt; i++, src++, p++, q++, r++) { 663 *p = 0; 664 *q = 0; 665 *r = 0; 666 } 667 } else { 668 ASSERT(ccnt <= pcnt); 669 670 /* 671 * Apply the algorithm described above by multiplying 672 * the previous result and adding in the new value. 673 */ 674 for (i = 0; i < ccnt; i++, src++, p++, q++, r++) { 675 *p ^= *src; 676 677 VDEV_RAIDZ_64MUL_2(*q, mask); 678 *q ^= *src; 679 680 VDEV_RAIDZ_64MUL_4(*r, mask); 681 *r ^= *src; 682 } 683 684 /* 685 * Treat short columns as though they are full of 0s. 686 * Note that there's therefore nothing needed for P. 687 */ 688 for (; i < pcnt; i++, q++, r++) { 689 VDEV_RAIDZ_64MUL_2(*q, mask); 690 VDEV_RAIDZ_64MUL_4(*r, mask); 691 } 692 } 693 } 694 } 695 696 /* 697 * Generate RAID parity in the first virtual columns according to the number of 698 * parity columns available. 699 */ 700 static void 701 vdev_raidz_generate_parity(raidz_map_t *rm) 702 { 703 switch (rm->rm_firstdatacol) { 704 case 1: 705 vdev_raidz_generate_parity_p(rm); 706 break; 707 case 2: 708 vdev_raidz_generate_parity_pq(rm); 709 break; 710 case 3: 711 vdev_raidz_generate_parity_pqr(rm); 712 break; 713 default: 714 cmn_err(CE_PANIC, "invalid RAID-Z configuration"); 715 } 716 } 717 718 static int 719 vdev_raidz_reconstruct_p(raidz_map_t *rm, int *tgts, int ntgts) 720 { 721 uint64_t *dst, *src, xcount, ccount, count, i; 722 int x = tgts[0]; 723 int c; 724 725 ASSERT(ntgts == 1); 726 ASSERT(x >= rm->rm_firstdatacol); 727 ASSERT(x < rm->rm_cols); 728 729 xcount = rm->rm_col[x].rc_size / sizeof (src[0]); 730 ASSERT(xcount <= rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (src[0])); 731 ASSERT(xcount > 0); 732 733 src = rm->rm_col[VDEV_RAIDZ_P].rc_data; 734 dst = rm->rm_col[x].rc_data; 735 for (i = 0; i < xcount; i++, dst++, src++) { 736 *dst = *src; 737 } 738 739 for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { 740 src = rm->rm_col[c].rc_data; 741 dst = rm->rm_col[x].rc_data; 742 743 if (c == x) 744 continue; 745 746 ccount = rm->rm_col[c].rc_size / sizeof (src[0]); 747 count = MIN(ccount, xcount); 748 749 for (i = 0; i < count; i++, dst++, src++) { 750 *dst ^= *src; 751 } 752 } 753 754 return (1 << VDEV_RAIDZ_P); 755 } 756 757 static int 758 vdev_raidz_reconstruct_q(raidz_map_t *rm, int *tgts, int ntgts) 759 { 760 uint64_t *dst, *src, xcount, ccount, count, mask, i; 761 uint8_t *b; 762 int x = tgts[0]; 763 int c, j, exp; 764 765 ASSERT(ntgts == 1); 766 767 xcount = rm->rm_col[x].rc_size / sizeof (src[0]); 768 ASSERT(xcount <= rm->rm_col[VDEV_RAIDZ_Q].rc_size / sizeof (src[0])); 769 770 for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { 771 src = rm->rm_col[c].rc_data; 772 dst = rm->rm_col[x].rc_data; 773 774 if (c == x) 775 ccount = 0; 776 else 777 ccount = rm->rm_col[c].rc_size / sizeof (src[0]); 778 779 count = MIN(ccount, xcount); 780 781 if (c == rm->rm_firstdatacol) { 782 for (i = 0; i < count; i++, dst++, src++) { 783 *dst = *src; 784 } 785 for (; i < xcount; i++, dst++) { 786 *dst = 0; 787 } 788 789 } else { 790 for (i = 0; i < count; i++, dst++, src++) { 791 VDEV_RAIDZ_64MUL_2(*dst, mask); 792 *dst ^= *src; 793 } 794 795 for (; i < xcount; i++, dst++) { 796 VDEV_RAIDZ_64MUL_2(*dst, mask); 797 } 798 } 799 } 800 801 src = rm->rm_col[VDEV_RAIDZ_Q].rc_data; 802 dst = rm->rm_col[x].rc_data; 803 exp = 255 - (rm->rm_cols - 1 - x); 804 805 for (i = 0; i < xcount; i++, dst++, src++) { 806 *dst ^= *src; 807 for (j = 0, b = (uint8_t *)dst; j < 8; j++, b++) { 808 *b = vdev_raidz_exp2(*b, exp); 809 } 810 } 811 812 return (1 << VDEV_RAIDZ_Q); 813 } 814 815 static int 816 vdev_raidz_reconstruct_pq(raidz_map_t *rm, int *tgts, int ntgts) 817 { 818 uint8_t *p, *q, *pxy, *qxy, *xd, *yd, tmp, a, b, aexp, bexp; 819 void *pdata, *qdata; 820 uint64_t xsize, ysize, i; 821 int x = tgts[0]; 822 int y = tgts[1]; 823 824 ASSERT(ntgts == 2); 825 ASSERT(x < y); 826 ASSERT(x >= rm->rm_firstdatacol); 827 ASSERT(y < rm->rm_cols); 828 829 ASSERT(rm->rm_col[x].rc_size >= rm->rm_col[y].rc_size); 830 831 /* 832 * Move the parity data aside -- we're going to compute parity as 833 * though columns x and y were full of zeros -- Pxy and Qxy. We want to 834 * reuse the parity generation mechanism without trashing the actual 835 * parity so we make those columns appear to be full of zeros by 836 * setting their lengths to zero. 837 */ 838 pdata = rm->rm_col[VDEV_RAIDZ_P].rc_data; 839 qdata = rm->rm_col[VDEV_RAIDZ_Q].rc_data; 840 xsize = rm->rm_col[x].rc_size; 841 ysize = rm->rm_col[y].rc_size; 842 843 rm->rm_col[VDEV_RAIDZ_P].rc_data = 844 zio_buf_alloc(rm->rm_col[VDEV_RAIDZ_P].rc_size); 845 rm->rm_col[VDEV_RAIDZ_Q].rc_data = 846 zio_buf_alloc(rm->rm_col[VDEV_RAIDZ_Q].rc_size); 847 rm->rm_col[x].rc_size = 0; 848 rm->rm_col[y].rc_size = 0; 849 850 vdev_raidz_generate_parity_pq(rm); 851 852 rm->rm_col[x].rc_size = xsize; 853 rm->rm_col[y].rc_size = ysize; 854 855 p = pdata; 856 q = qdata; 857 pxy = rm->rm_col[VDEV_RAIDZ_P].rc_data; 858 qxy = rm->rm_col[VDEV_RAIDZ_Q].rc_data; 859 xd = rm->rm_col[x].rc_data; 860 yd = rm->rm_col[y].rc_data; 861 862 /* 863 * We now have: 864 * Pxy = P + D_x + D_y 865 * Qxy = Q + 2^(ndevs - 1 - x) * D_x + 2^(ndevs - 1 - y) * D_y 866 * 867 * We can then solve for D_x: 868 * D_x = A * (P + Pxy) + B * (Q + Qxy) 869 * where 870 * A = 2^(x - y) * (2^(x - y) + 1)^-1 871 * B = 2^(ndevs - 1 - x) * (2^(x - y) + 1)^-1 872 * 873 * With D_x in hand, we can easily solve for D_y: 874 * D_y = P + Pxy + D_x 875 */ 876 877 a = vdev_raidz_pow2[255 + x - y]; 878 b = vdev_raidz_pow2[255 - (rm->rm_cols - 1 - x)]; 879 tmp = 255 - vdev_raidz_log2[a ^ 1]; 880 881 aexp = vdev_raidz_log2[vdev_raidz_exp2(a, tmp)]; 882 bexp = vdev_raidz_log2[vdev_raidz_exp2(b, tmp)]; 883 884 for (i = 0; i < xsize; i++, p++, q++, pxy++, qxy++, xd++, yd++) { 885 *xd = vdev_raidz_exp2(*p ^ *pxy, aexp) ^ 886 vdev_raidz_exp2(*q ^ *qxy, bexp); 887 888 if (i < ysize) 889 *yd = *p ^ *pxy ^ *xd; 890 } 891 892 zio_buf_free(rm->rm_col[VDEV_RAIDZ_P].rc_data, 893 rm->rm_col[VDEV_RAIDZ_P].rc_size); 894 zio_buf_free(rm->rm_col[VDEV_RAIDZ_Q].rc_data, 895 rm->rm_col[VDEV_RAIDZ_Q].rc_size); 896 897 /* 898 * Restore the saved parity data. 899 */ 900 rm->rm_col[VDEV_RAIDZ_P].rc_data = pdata; 901 rm->rm_col[VDEV_RAIDZ_Q].rc_data = qdata; 902 903 return ((1 << VDEV_RAIDZ_P) | (1 << VDEV_RAIDZ_Q)); 904 } 905 906 /* BEGIN CSTYLED */ 907 /* 908 * In the general case of reconstruction, we must solve the system of linear 909 * equations defined by the coeffecients used to generate parity as well as 910 * the contents of the data and parity disks. This can be expressed with 911 * vectors for the original data (D) and the actual data (d) and parity (p) 912 * and a matrix composed of the identity matrix (I) and a dispersal matrix (V): 913 * 914 * __ __ __ __ 915 * | | __ __ | p_0 | 916 * | V | | D_0 | | p_m-1 | 917 * | | x | : | = | d_0 | 918 * | I | | D_n-1 | | : | 919 * | | ~~ ~~ | d_n-1 | 920 * ~~ ~~ ~~ ~~ 921 * 922 * I is simply a square identity matrix of size n, and V is a vandermonde 923 * matrix defined by the coeffecients we chose for the various parity columns 924 * (1, 2, 4). Note that these values were chosen both for simplicity, speedy 925 * computation as well as linear separability. 926 * 927 * __ __ __ __ 928 * | 1 .. 1 1 1 | | p_0 | 929 * | 2^n-1 .. 4 2 1 | __ __ | : | 930 * | 4^n-1 .. 16 4 1 | | D_0 | | p_m-1 | 931 * | 1 .. 0 0 0 | | D_1 | | d_0 | 932 * | 0 .. 0 0 0 | x | D_2 | = | d_1 | 933 * | : : : : | | : | | d_2 | 934 * | 0 .. 1 0 0 | | D_n-1 | | : | 935 * | 0 .. 0 1 0 | ~~ ~~ | : | 936 * | 0 .. 0 0 1 | | d_n-1 | 937 * ~~ ~~ ~~ ~~ 938 * 939 * Note that I, V, d, and p are known. To compute D, we must invert the 940 * matrix and use the known data and parity values to reconstruct the unknown 941 * data values. We begin by removing the rows in V|I and d|p that correspond 942 * to failed or missing columns; we then make V|I square (n x n) and d|p 943 * sized n by removing rows corresponding to unused parity from the bottom up 944 * to generate (V|I)' and (d|p)'. We can then generate the inverse of (V|I)' 945 * using Gauss-Jordan elimination. In the example below we use m=3 parity 946 * columns, n=8 data columns, with errors in d_1, d_2, and p_1: 947 * __ __ 948 * | 1 1 1 1 1 1 1 1 | 949 * | 128 64 32 16 8 4 2 1 | <-----+-+-- missing disks 950 * | 19 205 116 29 64 16 4 1 | / / 951 * | 1 0 0 0 0 0 0 0 | / / 952 * | 0 1 0 0 0 0 0 0 | <--' / 953 * (V|I) = | 0 0 1 0 0 0 0 0 | <---' 954 * | 0 0 0 1 0 0 0 0 | 955 * | 0 0 0 0 1 0 0 0 | 956 * | 0 0 0 0 0 1 0 0 | 957 * | 0 0 0 0 0 0 1 0 | 958 * | 0 0 0 0 0 0 0 1 | 959 * ~~ ~~ 960 * __ __ 961 * | 1 1 1 1 1 1 1 1 | 962 * | 128 64 32 16 8 4 2 1 | 963 * | 19 205 116 29 64 16 4 1 | 964 * | 1 0 0 0 0 0 0 0 | 965 * | 0 1 0 0 0 0 0 0 | 966 * (V|I)' = | 0 0 1 0 0 0 0 0 | 967 * | 0 0 0 1 0 0 0 0 | 968 * | 0 0 0 0 1 0 0 0 | 969 * | 0 0 0 0 0 1 0 0 | 970 * | 0 0 0 0 0 0 1 0 | 971 * | 0 0 0 0 0 0 0 1 | 972 * ~~ ~~ 973 * 974 * Here we employ Gauss-Jordan elimination to find the inverse of (V|I)'. We 975 * have carefully chosen the seed values 1, 2, and 4 to ensure that this 976 * matrix is not singular. 977 * __ __ 978 * | 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 | 979 * | 19 205 116 29 64 16 4 1 0 1 0 0 0 0 0 0 | 980 * | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 | 981 * | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 | 982 * | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 | 983 * | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 | 984 * | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 | 985 * | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 | 986 * ~~ ~~ 987 * __ __ 988 * | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 | 989 * | 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 | 990 * | 19 205 116 29 64 16 4 1 0 1 0 0 0 0 0 0 | 991 * | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 | 992 * | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 | 993 * | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 | 994 * | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 | 995 * | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 | 996 * ~~ ~~ 997 * __ __ 998 * | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 | 999 * | 0 1 1 0 0 0 0 0 1 0 1 1 1 1 1 1 | 1000 * | 0 205 116 0 0 0 0 0 0 1 19 29 64 16 4 1 | 1001 * | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 | 1002 * | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 | 1003 * | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 | 1004 * | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 | 1005 * | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 | 1006 * ~~ ~~ 1007 * __ __ 1008 * | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 | 1009 * | 0 1 1 0 0 0 0 0 1 0 1 1 1 1 1 1 | 1010 * | 0 0 185 0 0 0 0 0 205 1 222 208 141 221 201 204 | 1011 * | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 | 1012 * | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 | 1013 * | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 | 1014 * | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 | 1015 * | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 | 1016 * ~~ ~~ 1017 * __ __ 1018 * | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 | 1019 * | 0 1 1 0 0 0 0 0 1 0 1 1 1 1 1 1 | 1020 * | 0 0 1 0 0 0 0 0 166 100 4 40 158 168 216 209 | 1021 * | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 | 1022 * | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 | 1023 * | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 | 1024 * | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 | 1025 * | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 | 1026 * ~~ ~~ 1027 * __ __ 1028 * | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 | 1029 * | 0 1 0 0 0 0 0 0 167 100 5 41 159 169 217 208 | 1030 * | 0 0 1 0 0 0 0 0 166 100 4 40 158 168 216 209 | 1031 * | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 | 1032 * | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 | 1033 * | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 | 1034 * | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 | 1035 * | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 | 1036 * ~~ ~~ 1037 * __ __ 1038 * | 0 0 1 0 0 0 0 0 | 1039 * | 167 100 5 41 159 169 217 208 | 1040 * | 166 100 4 40 158 168 216 209 | 1041 * (V|I)'^-1 = | 0 0 0 1 0 0 0 0 | 1042 * | 0 0 0 0 1 0 0 0 | 1043 * | 0 0 0 0 0 1 0 0 | 1044 * | 0 0 0 0 0 0 1 0 | 1045 * | 0 0 0 0 0 0 0 1 | 1046 * ~~ ~~ 1047 * 1048 * We can then simply compute D = (V|I)'^-1 x (d|p)' to discover the values 1049 * of the missing data. 1050 * 1051 * As is apparent from the example above, the only non-trivial rows in the 1052 * inverse matrix correspond to the data disks that we're trying to 1053 * reconstruct. Indeed, those are the only rows we need as the others would 1054 * only be useful for reconstructing data known or assumed to be valid. For 1055 * that reason, we only build the coefficients in the rows that correspond to 1056 * targeted columns. 1057 */ 1058 /* END CSTYLED */ 1059 1060 static void 1061 vdev_raidz_matrix_init(raidz_map_t *rm, int n, int nmap, int *map, 1062 uint8_t **rows) 1063 { 1064 int i, j; 1065 int pow; 1066 1067 ASSERT(n == rm->rm_cols - rm->rm_firstdatacol); 1068 1069 /* 1070 * Fill in the missing rows of interest. 1071 */ 1072 for (i = 0; i < nmap; i++) { 1073 ASSERT3S(0, <=, map[i]); 1074 ASSERT3S(map[i], <=, 2); 1075 1076 pow = map[i] * n; 1077 if (pow > 255) 1078 pow -= 255; 1079 ASSERT(pow <= 255); 1080 1081 for (j = 0; j < n; j++) { 1082 pow -= map[i]; 1083 if (pow < 0) 1084 pow += 255; 1085 rows[i][j] = vdev_raidz_pow2[pow]; 1086 } 1087 } 1088 } 1089 1090 static void 1091 vdev_raidz_matrix_invert(raidz_map_t *rm, int n, int nmissing, int *missing, 1092 uint8_t **rows, uint8_t **invrows, const uint8_t *used) 1093 { 1094 int i, j, ii, jj; 1095 uint8_t log; 1096 1097 /* 1098 * Assert that the first nmissing entries from the array of used 1099 * columns correspond to parity columns and that subsequent entries 1100 * correspond to data columns. 1101 */ 1102 for (i = 0; i < nmissing; i++) { 1103 ASSERT3S(used[i], <, rm->rm_firstdatacol); 1104 } 1105 for (; i < n; i++) { 1106 ASSERT3S(used[i], >=, rm->rm_firstdatacol); 1107 } 1108 1109 /* 1110 * First initialize the storage where we'll compute the inverse rows. 1111 */ 1112 for (i = 0; i < nmissing; i++) { 1113 for (j = 0; j < n; j++) { 1114 invrows[i][j] = (i == j) ? 1 : 0; 1115 } 1116 } 1117 1118 /* 1119 * Subtract all trivial rows from the rows of consequence. 1120 */ 1121 for (i = 0; i < nmissing; i++) { 1122 for (j = nmissing; j < n; j++) { 1123 ASSERT3U(used[j], >=, rm->rm_firstdatacol); 1124 jj = used[j] - rm->rm_firstdatacol; 1125 ASSERT3S(jj, <, n); 1126 invrows[i][j] = rows[i][jj]; 1127 rows[i][jj] = 0; 1128 } 1129 } 1130 1131 /* 1132 * For each of the rows of interest, we must normalize it and subtract 1133 * a multiple of it from the other rows. 1134 */ 1135 for (i = 0; i < nmissing; i++) { 1136 for (j = 0; j < missing[i]; j++) { 1137 ASSERT3U(rows[i][j], ==, 0); 1138 } 1139 ASSERT3U(rows[i][missing[i]], !=, 0); 1140 1141 /* 1142 * Compute the inverse of the first element and multiply each 1143 * element in the row by that value. 1144 */ 1145 log = 255 - vdev_raidz_log2[rows[i][missing[i]]]; 1146 1147 for (j = 0; j < n; j++) { 1148 rows[i][j] = vdev_raidz_exp2(rows[i][j], log); 1149 invrows[i][j] = vdev_raidz_exp2(invrows[i][j], log); 1150 } 1151 1152 for (ii = 0; ii < nmissing; ii++) { 1153 if (i == ii) 1154 continue; 1155 1156 ASSERT3U(rows[ii][missing[i]], !=, 0); 1157 1158 log = vdev_raidz_log2[rows[ii][missing[i]]]; 1159 1160 for (j = 0; j < n; j++) { 1161 rows[ii][j] ^= 1162 vdev_raidz_exp2(rows[i][j], log); 1163 invrows[ii][j] ^= 1164 vdev_raidz_exp2(invrows[i][j], log); 1165 } 1166 } 1167 } 1168 1169 /* 1170 * Verify that the data that is left in the rows are properly part of 1171 * an identity matrix. 1172 */ 1173 for (i = 0; i < nmissing; i++) { 1174 for (j = 0; j < n; j++) { 1175 if (j == missing[i]) { 1176 ASSERT3U(rows[i][j], ==, 1); 1177 } else { 1178 ASSERT3U(rows[i][j], ==, 0); 1179 } 1180 } 1181 } 1182 } 1183 1184 static void 1185 vdev_raidz_matrix_reconstruct(raidz_map_t *rm, int n, int nmissing, 1186 int *missing, uint8_t **invrows, const uint8_t *used) 1187 { 1188 int i, j, x, cc, c; 1189 uint8_t *src; 1190 uint64_t ccount; 1191 uint8_t *dst[VDEV_RAIDZ_MAXPARITY]; 1192 uint64_t dcount[VDEV_RAIDZ_MAXPARITY]; 1193 uint8_t log, val; 1194 int ll; 1195 uint8_t *invlog[VDEV_RAIDZ_MAXPARITY]; 1196 uint8_t *p, *pp; 1197 size_t psize; 1198 1199 psize = sizeof (invlog[0][0]) * n * nmissing; 1200 p = kmem_alloc(psize, KM_SLEEP); 1201 1202 for (pp = p, i = 0; i < nmissing; i++) { 1203 invlog[i] = pp; 1204 pp += n; 1205 } 1206 1207 for (i = 0; i < nmissing; i++) { 1208 for (j = 0; j < n; j++) { 1209 ASSERT3U(invrows[i][j], !=, 0); 1210 invlog[i][j] = vdev_raidz_log2[invrows[i][j]]; 1211 } 1212 } 1213 1214 for (i = 0; i < n; i++) { 1215 c = used[i]; 1216 ASSERT3U(c, <, rm->rm_cols); 1217 1218 src = rm->rm_col[c].rc_data; 1219 ccount = rm->rm_col[c].rc_size; 1220 for (j = 0; j < nmissing; j++) { 1221 cc = missing[j] + rm->rm_firstdatacol; 1222 ASSERT3U(cc, >=, rm->rm_firstdatacol); 1223 ASSERT3U(cc, <, rm->rm_cols); 1224 ASSERT3U(cc, !=, c); 1225 1226 dst[j] = rm->rm_col[cc].rc_data; 1227 dcount[j] = rm->rm_col[cc].rc_size; 1228 } 1229 1230 ASSERT(ccount >= rm->rm_col[missing[0]].rc_size || i > 0); 1231 1232 for (x = 0; x < ccount; x++, src++) { 1233 if (*src != 0) 1234 log = vdev_raidz_log2[*src]; 1235 1236 for (cc = 0; cc < nmissing; cc++) { 1237 if (x >= dcount[cc]) 1238 continue; 1239 1240 if (*src == 0) { 1241 val = 0; 1242 } else { 1243 if ((ll = log + invlog[cc][i]) >= 255) 1244 ll -= 255; 1245 val = vdev_raidz_pow2[ll]; 1246 } 1247 1248 if (i == 0) 1249 dst[cc][x] = val; 1250 else 1251 dst[cc][x] ^= val; 1252 } 1253 } 1254 } 1255 1256 kmem_free(p, psize); 1257 } 1258 1259 static int 1260 vdev_raidz_reconstruct_general(raidz_map_t *rm, int *tgts, int ntgts) 1261 { 1262 int n, i, c, t, tt; 1263 int nmissing_rows; 1264 int missing_rows[VDEV_RAIDZ_MAXPARITY]; 1265 int parity_map[VDEV_RAIDZ_MAXPARITY]; 1266 1267 uint8_t *p, *pp; 1268 size_t psize; 1269 1270 uint8_t *rows[VDEV_RAIDZ_MAXPARITY]; 1271 uint8_t *invrows[VDEV_RAIDZ_MAXPARITY]; 1272 uint8_t *used; 1273 1274 int code = 0; 1275 1276 1277 n = rm->rm_cols - rm->rm_firstdatacol; 1278 1279 /* 1280 * Figure out which data columns are missing. 1281 */ 1282 nmissing_rows = 0; 1283 for (t = 0; t < ntgts; t++) { 1284 if (tgts[t] >= rm->rm_firstdatacol) { 1285 missing_rows[nmissing_rows++] = 1286 tgts[t] - rm->rm_firstdatacol; 1287 } 1288 } 1289 1290 /* 1291 * Figure out which parity columns to use to help generate the missing 1292 * data columns. 1293 */ 1294 for (tt = 0, c = 0, i = 0; i < nmissing_rows; c++) { 1295 ASSERT(tt < ntgts); 1296 ASSERT(c < rm->rm_firstdatacol); 1297 1298 /* 1299 * Skip any targeted parity columns. 1300 */ 1301 if (c == tgts[tt]) { 1302 tt++; 1303 continue; 1304 } 1305 1306 code |= 1 << c; 1307 1308 parity_map[i] = c; 1309 i++; 1310 } 1311 1312 ASSERT(code != 0); 1313 ASSERT3U(code, <, 1 << VDEV_RAIDZ_MAXPARITY); 1314 1315 psize = (sizeof (rows[0][0]) + sizeof (invrows[0][0])) * 1316 nmissing_rows * n + sizeof (used[0]) * n; 1317 p = kmem_alloc(psize, KM_SLEEP); 1318 1319 for (pp = p, i = 0; i < nmissing_rows; i++) { 1320 rows[i] = pp; 1321 pp += n; 1322 invrows[i] = pp; 1323 pp += n; 1324 } 1325 used = pp; 1326 1327 for (i = 0; i < nmissing_rows; i++) { 1328 used[i] = parity_map[i]; 1329 } 1330 1331 for (tt = 0, c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { 1332 if (tt < nmissing_rows && 1333 c == missing_rows[tt] + rm->rm_firstdatacol) { 1334 tt++; 1335 continue; 1336 } 1337 1338 ASSERT3S(i, <, n); 1339 used[i] = c; 1340 i++; 1341 } 1342 1343 /* 1344 * Initialize the interesting rows of the matrix. 1345 */ 1346 vdev_raidz_matrix_init(rm, n, nmissing_rows, parity_map, rows); 1347 1348 /* 1349 * Invert the matrix. 1350 */ 1351 vdev_raidz_matrix_invert(rm, n, nmissing_rows, missing_rows, rows, 1352 invrows, used); 1353 1354 /* 1355 * Reconstruct the missing data using the generated matrix. 1356 */ 1357 vdev_raidz_matrix_reconstruct(rm, n, nmissing_rows, missing_rows, 1358 invrows, used); 1359 1360 kmem_free(p, psize); 1361 1362 return (code); 1363 } 1364 1365 static int 1366 vdev_raidz_reconstruct(raidz_map_t *rm, int *t, int nt) 1367 { 1368 int tgts[VDEV_RAIDZ_MAXPARITY], *dt; 1369 int ntgts; 1370 int i, c; 1371 int code; 1372 int nbadparity, nbaddata; 1373 int parity_valid[VDEV_RAIDZ_MAXPARITY]; 1374 1375 /* 1376 * The tgts list must already be sorted. 1377 */ 1378 for (i = 1; i < nt; i++) { 1379 ASSERT(t[i] > t[i - 1]); 1380 } 1381 1382 nbadparity = rm->rm_firstdatacol; 1383 nbaddata = rm->rm_cols - nbadparity; 1384 ntgts = 0; 1385 for (i = 0, c = 0; c < rm->rm_cols; c++) { 1386 if (c < rm->rm_firstdatacol) 1387 parity_valid[c] = B_FALSE; 1388 1389 if (i < nt && c == t[i]) { 1390 tgts[ntgts++] = c; 1391 i++; 1392 } else if (rm->rm_col[c].rc_error != 0) { 1393 tgts[ntgts++] = c; 1394 } else if (c >= rm->rm_firstdatacol) { 1395 nbaddata--; 1396 } else { 1397 parity_valid[c] = B_TRUE; 1398 nbadparity--; 1399 } 1400 } 1401 1402 ASSERT(ntgts >= nt); 1403 ASSERT(nbaddata >= 0); 1404 ASSERT(nbaddata + nbadparity == ntgts); 1405 1406 dt = &tgts[nbadparity]; 1407 1408 /* 1409 * See if we can use any of our optimized reconstruction routines. 1410 */ 1411 if (!vdev_raidz_default_to_general) { 1412 switch (nbaddata) { 1413 case 1: 1414 if (parity_valid[VDEV_RAIDZ_P]) 1415 return (vdev_raidz_reconstruct_p(rm, dt, 1)); 1416 1417 ASSERT(rm->rm_firstdatacol > 1); 1418 1419 if (parity_valid[VDEV_RAIDZ_Q]) 1420 return (vdev_raidz_reconstruct_q(rm, dt, 1)); 1421 1422 ASSERT(rm->rm_firstdatacol > 2); 1423 break; 1424 1425 case 2: 1426 ASSERT(rm->rm_firstdatacol > 1); 1427 1428 if (parity_valid[VDEV_RAIDZ_P] && 1429 parity_valid[VDEV_RAIDZ_Q]) 1430 return (vdev_raidz_reconstruct_pq(rm, dt, 2)); 1431 1432 ASSERT(rm->rm_firstdatacol > 2); 1433 1434 break; 1435 } 1436 } 1437 1438 code = vdev_raidz_reconstruct_general(rm, tgts, ntgts); 1439 ASSERT(code < (1 << VDEV_RAIDZ_MAXPARITY)); 1440 ASSERT(code > 0); 1441 return (code); 1442 } 1443 1444 static int 1445 vdev_raidz_open(vdev_t *vd, uint64_t *asize, uint64_t *ashift) 1446 { 1447 vdev_t *cvd; 1448 uint64_t nparity = vd->vdev_nparity; 1449 int c; 1450 int lasterror = 0; 1451 int numerrors = 0; 1452 1453 ASSERT(nparity > 0); 1454 1455 if (nparity > VDEV_RAIDZ_MAXPARITY || 1456 vd->vdev_children < nparity + 1) { 1457 vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL; 1458 return (EINVAL); 1459 } 1460 1461 vdev_open_children(vd); 1462 1463 for (c = 0; c < vd->vdev_children; c++) { 1464 cvd = vd->vdev_child[c]; 1465 1466 if (cvd->vdev_open_error != 0) { 1467 lasterror = cvd->vdev_open_error; 1468 numerrors++; 1469 continue; 1470 } 1471 1472 *asize = MIN(*asize - 1, cvd->vdev_asize - 1) + 1; 1473 *ashift = MAX(*ashift, cvd->vdev_ashift); 1474 } 1475 1476 *asize *= vd->vdev_children; 1477 1478 if (numerrors > nparity) { 1479 vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS; 1480 return (lasterror); 1481 } 1482 1483 return (0); 1484 } 1485 1486 static void 1487 vdev_raidz_close(vdev_t *vd) 1488 { 1489 int c; 1490 1491 for (c = 0; c < vd->vdev_children; c++) 1492 vdev_close(vd->vdev_child[c]); 1493 } 1494 1495 static uint64_t 1496 vdev_raidz_asize(vdev_t *vd, uint64_t psize) 1497 { 1498 uint64_t asize; 1499 uint64_t ashift = vd->vdev_top->vdev_ashift; 1500 uint64_t cols = vd->vdev_children; 1501 uint64_t nparity = vd->vdev_nparity; 1502 1503 asize = ((psize - 1) >> ashift) + 1; 1504 asize += nparity * ((asize + cols - nparity - 1) / (cols - nparity)); 1505 asize = roundup(asize, nparity + 1) << ashift; 1506 1507 return (asize); 1508 } 1509 1510 static void 1511 vdev_raidz_child_done(zio_t *zio) 1512 { 1513 raidz_col_t *rc = zio->io_private; 1514 1515 rc->rc_error = zio->io_error; 1516 rc->rc_tried = 1; 1517 rc->rc_skipped = 0; 1518 } 1519 1520 static int 1521 vdev_raidz_io_start(zio_t *zio) 1522 { 1523 vdev_t *vd = zio->io_vd; 1524 vdev_t *tvd = vd->vdev_top; 1525 vdev_t *cvd; 1526 raidz_map_t *rm; 1527 raidz_col_t *rc; 1528 int c, i; 1529 1530 rm = vdev_raidz_map_alloc(zio, tvd->vdev_ashift, vd->vdev_children, 1531 vd->vdev_nparity); 1532 1533 ASSERT3U(rm->rm_asize, ==, vdev_psize_to_asize(vd, zio->io_size)); 1534 1535 if (zio->io_type == ZIO_TYPE_WRITE) { 1536 vdev_raidz_generate_parity(rm); 1537 1538 for (c = 0; c < rm->rm_cols; c++) { 1539 rc = &rm->rm_col[c]; 1540 cvd = vd->vdev_child[rc->rc_devidx]; 1541 zio_nowait(zio_vdev_child_io(zio, NULL, cvd, 1542 rc->rc_offset, rc->rc_data, rc->rc_size, 1543 zio->io_type, zio->io_priority, 0, 1544 vdev_raidz_child_done, rc)); 1545 } 1546 1547 /* 1548 * Generate optional I/Os for any skipped sectors to improve 1549 * aggregation contiguity. 1550 */ 1551 for (c = rm->rm_skipstart, i = 0; i < rm->rm_nskip; c++, i++) { 1552 ASSERT(c <= rm->rm_scols); 1553 if (c == rm->rm_scols) 1554 c = 0; 1555 rc = &rm->rm_col[c]; 1556 cvd = vd->vdev_child[rc->rc_devidx]; 1557 zio_nowait(zio_vdev_child_io(zio, NULL, cvd, 1558 rc->rc_offset + rc->rc_size, NULL, 1559 1 << tvd->vdev_ashift, 1560 zio->io_type, zio->io_priority, 1561 ZIO_FLAG_NODATA | ZIO_FLAG_OPTIONAL, NULL, NULL)); 1562 } 1563 1564 return (ZIO_PIPELINE_CONTINUE); 1565 } 1566 1567 ASSERT(zio->io_type == ZIO_TYPE_READ); 1568 1569 /* 1570 * Iterate over the columns in reverse order so that we hit the parity 1571 * last -- any errors along the way will force us to read the parity. 1572 */ 1573 for (c = rm->rm_cols - 1; c >= 0; c--) { 1574 rc = &rm->rm_col[c]; 1575 cvd = vd->vdev_child[rc->rc_devidx]; 1576 if (!vdev_readable(cvd)) { 1577 if (c >= rm->rm_firstdatacol) 1578 rm->rm_missingdata++; 1579 else 1580 rm->rm_missingparity++; 1581 rc->rc_error = ENXIO; 1582 rc->rc_tried = 1; /* don't even try */ 1583 rc->rc_skipped = 1; 1584 continue; 1585 } 1586 if (vdev_dtl_contains(cvd, DTL_MISSING, zio->io_txg, 1)) { 1587 if (c >= rm->rm_firstdatacol) 1588 rm->rm_missingdata++; 1589 else 1590 rm->rm_missingparity++; 1591 rc->rc_error = ESTALE; 1592 rc->rc_skipped = 1; 1593 continue; 1594 } 1595 if (c >= rm->rm_firstdatacol || rm->rm_missingdata > 0 || 1596 (zio->io_flags & (ZIO_FLAG_SCRUB | ZIO_FLAG_RESILVER))) { 1597 zio_nowait(zio_vdev_child_io(zio, NULL, cvd, 1598 rc->rc_offset, rc->rc_data, rc->rc_size, 1599 zio->io_type, zio->io_priority, 0, 1600 vdev_raidz_child_done, rc)); 1601 } 1602 } 1603 1604 return (ZIO_PIPELINE_CONTINUE); 1605 } 1606 1607 /* 1608 * Report a checksum error for a child of a RAID-Z device. 1609 */ 1610 static void 1611 raidz_checksum_error(zio_t *zio, raidz_col_t *rc, void *bad_data) 1612 { 1613 vdev_t *vd = zio->io_vd->vdev_child[rc->rc_devidx]; 1614 1615 if (!(zio->io_flags & ZIO_FLAG_SPECULATIVE)) { 1616 zio_bad_cksum_t zbc; 1617 raidz_map_t *rm = zio->io_vsd; 1618 1619 mutex_enter(&vd->vdev_stat_lock); 1620 vd->vdev_stat.vs_checksum_errors++; 1621 mutex_exit(&vd->vdev_stat_lock); 1622 1623 zbc.zbc_has_cksum = 0; 1624 zbc.zbc_injected = rm->rm_ecksuminjected; 1625 1626 zfs_ereport_post_checksum(zio->io_spa, vd, zio, 1627 rc->rc_offset, rc->rc_size, rc->rc_data, bad_data, 1628 &zbc); 1629 } 1630 } 1631 1632 /* 1633 * We keep track of whether or not there were any injected errors, so that 1634 * any ereports we generate can note it. 1635 */ 1636 static int 1637 raidz_checksum_verify(zio_t *zio) 1638 { 1639 zio_bad_cksum_t zbc; 1640 raidz_map_t *rm = zio->io_vsd; 1641 1642 int ret = zio_checksum_error(zio, &zbc); 1643 if (ret != 0 && zbc.zbc_injected != 0) 1644 rm->rm_ecksuminjected = 1; 1645 1646 return (ret); 1647 } 1648 1649 /* 1650 * Generate the parity from the data columns. If we tried and were able to 1651 * read the parity without error, verify that the generated parity matches the 1652 * data we read. If it doesn't, we fire off a checksum error. Return the 1653 * number such failures. 1654 */ 1655 static int 1656 raidz_parity_verify(zio_t *zio, raidz_map_t *rm) 1657 { 1658 void *orig[VDEV_RAIDZ_MAXPARITY]; 1659 int c, ret = 0; 1660 raidz_col_t *rc; 1661 1662 for (c = 0; c < rm->rm_firstdatacol; c++) { 1663 rc = &rm->rm_col[c]; 1664 if (!rc->rc_tried || rc->rc_error != 0) 1665 continue; 1666 orig[c] = zio_buf_alloc(rc->rc_size); 1667 bcopy(rc->rc_data, orig[c], rc->rc_size); 1668 } 1669 1670 vdev_raidz_generate_parity(rm); 1671 1672 for (c = 0; c < rm->rm_firstdatacol; c++) { 1673 rc = &rm->rm_col[c]; 1674 if (!rc->rc_tried || rc->rc_error != 0) 1675 continue; 1676 if (bcmp(orig[c], rc->rc_data, rc->rc_size) != 0) { 1677 raidz_checksum_error(zio, rc, orig[c]); 1678 rc->rc_error = ECKSUM; 1679 ret++; 1680 } 1681 zio_buf_free(orig[c], rc->rc_size); 1682 } 1683 1684 return (ret); 1685 } 1686 1687 /* 1688 * Keep statistics on all the ways that we used parity to correct data. 1689 */ 1690 static uint64_t raidz_corrected[1 << VDEV_RAIDZ_MAXPARITY]; 1691 1692 static int 1693 vdev_raidz_worst_error(raidz_map_t *rm) 1694 { 1695 int error = 0; 1696 1697 for (int c = 0; c < rm->rm_cols; c++) 1698 error = zio_worst_error(error, rm->rm_col[c].rc_error); 1699 1700 return (error); 1701 } 1702 1703 /* 1704 * Iterate over all combinations of bad data and attempt a reconstruction. 1705 * Note that the algorithm below is non-optimal because it doesn't take into 1706 * account how reconstruction is actually performed. For example, with 1707 * triple-parity RAID-Z the reconstruction procedure is the same if column 4 1708 * is targeted as invalid as if columns 1 and 4 are targeted since in both 1709 * cases we'd only use parity information in column 0. 1710 */ 1711 static int 1712 vdev_raidz_combrec(zio_t *zio, int total_errors, int data_errors) 1713 { 1714 raidz_map_t *rm = zio->io_vsd; 1715 raidz_col_t *rc; 1716 void *orig[VDEV_RAIDZ_MAXPARITY]; 1717 int tstore[VDEV_RAIDZ_MAXPARITY + 2]; 1718 int *tgts = &tstore[1]; 1719 int current, next, i, c, n; 1720 int code, ret = 0; 1721 1722 ASSERT(total_errors < rm->rm_firstdatacol); 1723 1724 /* 1725 * This simplifies one edge condition. 1726 */ 1727 tgts[-1] = -1; 1728 1729 for (n = 1; n <= rm->rm_firstdatacol - total_errors; n++) { 1730 /* 1731 * Initialize the targets array by finding the first n columns 1732 * that contain no error. 1733 * 1734 * If there were no data errors, we need to ensure that we're 1735 * always explicitly attempting to reconstruct at least one 1736 * data column. To do this, we simply push the highest target 1737 * up into the data columns. 1738 */ 1739 for (c = 0, i = 0; i < n; i++) { 1740 if (i == n - 1 && data_errors == 0 && 1741 c < rm->rm_firstdatacol) { 1742 c = rm->rm_firstdatacol; 1743 } 1744 1745 while (rm->rm_col[c].rc_error != 0) { 1746 c++; 1747 ASSERT3S(c, <, rm->rm_cols); 1748 } 1749 1750 tgts[i] = c++; 1751 } 1752 1753 /* 1754 * Setting tgts[n] simplifies the other edge condition. 1755 */ 1756 tgts[n] = rm->rm_cols; 1757 1758 /* 1759 * These buffers were allocated in previous iterations. 1760 */ 1761 for (i = 0; i < n - 1; i++) { 1762 ASSERT(orig[i] != NULL); 1763 } 1764 1765 orig[n - 1] = zio_buf_alloc(rm->rm_col[0].rc_size); 1766 1767 current = 0; 1768 next = tgts[current]; 1769 1770 while (current != n) { 1771 tgts[current] = next; 1772 current = 0; 1773 1774 /* 1775 * Save off the original data that we're going to 1776 * attempt to reconstruct. 1777 */ 1778 for (i = 0; i < n; i++) { 1779 ASSERT(orig[i] != NULL); 1780 c = tgts[i]; 1781 ASSERT3S(c, >=, 0); 1782 ASSERT3S(c, <, rm->rm_cols); 1783 rc = &rm->rm_col[c]; 1784 bcopy(rc->rc_data, orig[i], rc->rc_size); 1785 } 1786 1787 /* 1788 * Attempt a reconstruction and exit the outer loop on 1789 * success. 1790 */ 1791 code = vdev_raidz_reconstruct(rm, tgts, n); 1792 if (raidz_checksum_verify(zio) == 0) { 1793 atomic_inc_64(&raidz_corrected[code]); 1794 1795 for (i = 0; i < n; i++) { 1796 c = tgts[i]; 1797 rc = &rm->rm_col[c]; 1798 ASSERT(rc->rc_error == 0); 1799 if (rc->rc_tried) 1800 raidz_checksum_error(zio, rc, 1801 orig[i]); 1802 rc->rc_error = ECKSUM; 1803 } 1804 1805 ret = code; 1806 goto done; 1807 } 1808 1809 /* 1810 * Restore the original data. 1811 */ 1812 for (i = 0; i < n; i++) { 1813 c = tgts[i]; 1814 rc = &rm->rm_col[c]; 1815 bcopy(orig[i], rc->rc_data, rc->rc_size); 1816 } 1817 1818 do { 1819 /* 1820 * Find the next valid column after the current 1821 * position.. 1822 */ 1823 for (next = tgts[current] + 1; 1824 next < rm->rm_cols && 1825 rm->rm_col[next].rc_error != 0; next++) 1826 continue; 1827 1828 ASSERT(next <= tgts[current + 1]); 1829 1830 /* 1831 * If that spot is available, we're done here. 1832 */ 1833 if (next != tgts[current + 1]) 1834 break; 1835 1836 /* 1837 * Otherwise, find the next valid column after 1838 * the previous position. 1839 */ 1840 for (c = tgts[current - 1] + 1; 1841 rm->rm_col[c].rc_error != 0; c++) 1842 continue; 1843 1844 tgts[current] = c; 1845 current++; 1846 1847 } while (current != n); 1848 } 1849 } 1850 n--; 1851 done: 1852 for (i = 0; i < n; i++) { 1853 zio_buf_free(orig[i], rm->rm_col[0].rc_size); 1854 } 1855 1856 return (ret); 1857 } 1858 1859 static void 1860 vdev_raidz_io_done(zio_t *zio) 1861 { 1862 vdev_t *vd = zio->io_vd; 1863 vdev_t *cvd; 1864 raidz_map_t *rm = zio->io_vsd; 1865 raidz_col_t *rc; 1866 int unexpected_errors = 0; 1867 int parity_errors = 0; 1868 int parity_untried = 0; 1869 int data_errors = 0; 1870 int total_errors = 0; 1871 int n, c; 1872 int tgts[VDEV_RAIDZ_MAXPARITY]; 1873 int code; 1874 1875 ASSERT(zio->io_bp != NULL); /* XXX need to add code to enforce this */ 1876 1877 ASSERT(rm->rm_missingparity <= rm->rm_firstdatacol); 1878 ASSERT(rm->rm_missingdata <= rm->rm_cols - rm->rm_firstdatacol); 1879 1880 for (c = 0; c < rm->rm_cols; c++) { 1881 rc = &rm->rm_col[c]; 1882 1883 if (rc->rc_error) { 1884 ASSERT(rc->rc_error != ECKSUM); /* child has no bp */ 1885 1886 if (c < rm->rm_firstdatacol) 1887 parity_errors++; 1888 else 1889 data_errors++; 1890 1891 if (!rc->rc_skipped) 1892 unexpected_errors++; 1893 1894 total_errors++; 1895 } else if (c < rm->rm_firstdatacol && !rc->rc_tried) { 1896 parity_untried++; 1897 } 1898 } 1899 1900 if (zio->io_type == ZIO_TYPE_WRITE) { 1901 /* 1902 * XXX -- for now, treat partial writes as a success. 1903 * (If we couldn't write enough columns to reconstruct 1904 * the data, the I/O failed. Otherwise, good enough.) 1905 * 1906 * Now that we support write reallocation, it would be better 1907 * to treat partial failure as real failure unless there are 1908 * no non-degraded top-level vdevs left, and not update DTLs 1909 * if we intend to reallocate. 1910 */ 1911 /* XXPOLICY */ 1912 if (total_errors > rm->rm_firstdatacol) 1913 zio->io_error = vdev_raidz_worst_error(rm); 1914 1915 return; 1916 } 1917 1918 ASSERT(zio->io_type == ZIO_TYPE_READ); 1919 /* 1920 * There are three potential phases for a read: 1921 * 1. produce valid data from the columns read 1922 * 2. read all disks and try again 1923 * 3. perform combinatorial reconstruction 1924 * 1925 * Each phase is progressively both more expensive and less likely to 1926 * occur. If we encounter more errors than we can repair or all phases 1927 * fail, we have no choice but to return an error. 1928 */ 1929 1930 /* 1931 * If the number of errors we saw was correctable -- less than or equal 1932 * to the number of parity disks read -- attempt to produce data that 1933 * has a valid checksum. Naturally, this case applies in the absence of 1934 * any errors. 1935 */ 1936 if (total_errors <= rm->rm_firstdatacol - parity_untried) { 1937 if (data_errors == 0) { 1938 if (raidz_checksum_verify(zio) == 0) { 1939 /* 1940 * If we read parity information (unnecessarily 1941 * as it happens since no reconstruction was 1942 * needed) regenerate and verify the parity. 1943 * We also regenerate parity when resilvering 1944 * so we can write it out to the failed device 1945 * later. 1946 */ 1947 if (parity_errors + parity_untried < 1948 rm->rm_firstdatacol || 1949 (zio->io_flags & ZIO_FLAG_RESILVER)) { 1950 n = raidz_parity_verify(zio, rm); 1951 unexpected_errors += n; 1952 ASSERT(parity_errors + n <= 1953 rm->rm_firstdatacol); 1954 } 1955 goto done; 1956 } 1957 } else { 1958 /* 1959 * We either attempt to read all the parity columns or 1960 * none of them. If we didn't try to read parity, we 1961 * wouldn't be here in the correctable case. There must 1962 * also have been fewer parity errors than parity 1963 * columns or, again, we wouldn't be in this code path. 1964 */ 1965 ASSERT(parity_untried == 0); 1966 ASSERT(parity_errors < rm->rm_firstdatacol); 1967 1968 /* 1969 * Identify the data columns that reported an error. 1970 */ 1971 n = 0; 1972 for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { 1973 rc = &rm->rm_col[c]; 1974 if (rc->rc_error != 0) { 1975 ASSERT(n < VDEV_RAIDZ_MAXPARITY); 1976 tgts[n++] = c; 1977 } 1978 } 1979 1980 ASSERT(rm->rm_firstdatacol >= n); 1981 1982 code = vdev_raidz_reconstruct(rm, tgts, n); 1983 1984 if (raidz_checksum_verify(zio) == 0) { 1985 atomic_inc_64(&raidz_corrected[code]); 1986 1987 /* 1988 * If we read more parity disks than were used 1989 * for reconstruction, confirm that the other 1990 * parity disks produced correct data. This 1991 * routine is suboptimal in that it regenerates 1992 * the parity that we already used in addition 1993 * to the parity that we're attempting to 1994 * verify, but this should be a relatively 1995 * uncommon case, and can be optimized if it 1996 * becomes a problem. Note that we regenerate 1997 * parity when resilvering so we can write it 1998 * out to failed devices later. 1999 */ 2000 if (parity_errors < rm->rm_firstdatacol - n || 2001 (zio->io_flags & ZIO_FLAG_RESILVER)) { 2002 n = raidz_parity_verify(zio, rm); 2003 unexpected_errors += n; 2004 ASSERT(parity_errors + n <= 2005 rm->rm_firstdatacol); 2006 } 2007 2008 goto done; 2009 } 2010 } 2011 } 2012 2013 /* 2014 * This isn't a typical situation -- either we got a read error or 2015 * a child silently returned bad data. Read every block so we can 2016 * try again with as much data and parity as we can track down. If 2017 * we've already been through once before, all children will be marked 2018 * as tried so we'll proceed to combinatorial reconstruction. 2019 */ 2020 unexpected_errors = 1; 2021 rm->rm_missingdata = 0; 2022 rm->rm_missingparity = 0; 2023 2024 for (c = 0; c < rm->rm_cols; c++) { 2025 if (rm->rm_col[c].rc_tried) 2026 continue; 2027 2028 zio_vdev_io_redone(zio); 2029 do { 2030 rc = &rm->rm_col[c]; 2031 if (rc->rc_tried) 2032 continue; 2033 zio_nowait(zio_vdev_child_io(zio, NULL, 2034 vd->vdev_child[rc->rc_devidx], 2035 rc->rc_offset, rc->rc_data, rc->rc_size, 2036 zio->io_type, zio->io_priority, 0, 2037 vdev_raidz_child_done, rc)); 2038 } while (++c < rm->rm_cols); 2039 2040 return; 2041 } 2042 2043 /* 2044 * At this point we've attempted to reconstruct the data given the 2045 * errors we detected, and we've attempted to read all columns. There 2046 * must, therefore, be one or more additional problems -- silent errors 2047 * resulting in invalid data rather than explicit I/O errors resulting 2048 * in absent data. We check if there is enough additional data to 2049 * possibly reconstruct the data and then perform combinatorial 2050 * reconstruction over all possible combinations. If that fails, 2051 * we're cooked. 2052 */ 2053 if (total_errors > rm->rm_firstdatacol) { 2054 zio->io_error = vdev_raidz_worst_error(rm); 2055 2056 } else if (total_errors < rm->rm_firstdatacol && 2057 (code = vdev_raidz_combrec(zio, total_errors, data_errors)) != 0) { 2058 /* 2059 * If we didn't use all the available parity for the 2060 * combinatorial reconstruction, verify that the remaining 2061 * parity is correct. 2062 */ 2063 if (code != (1 << rm->rm_firstdatacol) - 1) 2064 (void) raidz_parity_verify(zio, rm); 2065 } else { 2066 /* 2067 * We're here because either: 2068 * 2069 * total_errors == rm_first_datacol, or 2070 * vdev_raidz_combrec() failed 2071 * 2072 * In either case, there is enough bad data to prevent 2073 * reconstruction. 2074 * 2075 * Start checksum ereports for all children which haven't 2076 * failed. 2077 */ 2078 zio->io_error = ECKSUM; 2079 2080 for (c = 0; c < rm->rm_cols; c++) { 2081 rc = &rm->rm_col[c]; 2082 if (rc->rc_error == 0) { 2083 zio_bad_cksum_t zbc; 2084 zbc.zbc_has_cksum = 0; 2085 zbc.zbc_injected = rm->rm_ecksuminjected; 2086 2087 zfs_ereport_start_checksum( 2088 zio->io_spa, vd->vdev_child[rc->rc_devidx], 2089 zio, rc->rc_offset, rc->rc_size, 2090 (void *)(uintptr_t)c, &zbc); 2091 } 2092 } 2093 } 2094 2095 done: 2096 zio_checksum_verified(zio); 2097 2098 if (zio->io_error == 0 && spa_writeable(zio->io_spa) && 2099 (unexpected_errors || (zio->io_flags & ZIO_FLAG_RESILVER))) { 2100 /* 2101 * Use the good data we have in hand to repair damaged children. 2102 */ 2103 for (c = 0; c < rm->rm_cols; c++) { 2104 rc = &rm->rm_col[c]; 2105 cvd = vd->vdev_child[rc->rc_devidx]; 2106 2107 if (rc->rc_error == 0) 2108 continue; 2109 2110 zio_nowait(zio_vdev_child_io(zio, NULL, cvd, 2111 rc->rc_offset, rc->rc_data, rc->rc_size, 2112 ZIO_TYPE_WRITE, zio->io_priority, 2113 ZIO_FLAG_IO_REPAIR | (unexpected_errors ? 2114 ZIO_FLAG_SELF_HEAL : 0), NULL, NULL)); 2115 } 2116 } 2117 } 2118 2119 static void 2120 vdev_raidz_state_change(vdev_t *vd, int faulted, int degraded) 2121 { 2122 if (faulted > vd->vdev_nparity) 2123 vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN, 2124 VDEV_AUX_NO_REPLICAS); 2125 else if (degraded + faulted != 0) 2126 vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE); 2127 else 2128 vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE); 2129 } 2130 2131 vdev_ops_t vdev_raidz_ops = { 2132 vdev_raidz_open, 2133 vdev_raidz_close, 2134 vdev_raidz_asize, 2135 vdev_raidz_io_start, 2136 vdev_raidz_io_done, 2137 vdev_raidz_state_change, 2138 VDEV_TYPE_RAIDZ, /* name of this vdev type */ 2139 B_FALSE /* not a leaf vdev */ 2140 }; 2141
Indexes created Thu Nov 26 17:05:41 UTC 2009
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