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 * Copyright 2006 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26 #pragma ident "%Z%%M% %I% %E% SMI" 27 28 /* 29 * Routines to manage the on-disk persistent error log. 30 * 31 * Each pool stores a log of all logical data errors seen during normal 32 * operation. This is actually the union of two distinct logs: the last log, 33 * and the current log. All errors seen are logged to the current log. When a 34 * scrub completes, the current log becomes the last log, the last log is thrown 35 * out, and the current log is reinitialized. This way, if an error is somehow 36 * corrected, a new scrub will show that that it no longer exists, and will be 37 * deleted from the log when the scrub completes. 38 * 39 * The log is stored using a ZAP object whose key is a string form of the 40 * zbookmark tuple (objset, object, level, blkid), and whose contents is an 41 * optional 'objset:object' human-readable string describing the data. When an 42 * error is first logged, this string will be empty, indicating that no name is 43 * known. This prevents us from having to issue a potentially large amount of 44 * I/O to discover the object name during an error path. Instead, we do the 45 * calculation when the data is requested, storing the result so future queries 46 * will be faster. 47 * 48 * This log is then shipped into an nvlist where the key is the dataset name and 49 * the value is the object name. Userland is then responsible for uniquifying 50 * this list and displaying it to the user. 51 */ 52 53 #include <sys/dmu_tx.h> 54 #include <sys/spa.h> 55 #include <sys/spa_impl.h> 56 #include <sys/zap.h> 57 #include <sys/zio.h> 58 59 /* 60 * This is a stripped-down version of strtoull, suitable only for converting 61 * lowercase hexidecimal numbers that don't overflow. 62 */ 63 static uint64_t 64 strtonum(char *str, char **nptr) 65 { 66 uint64_t val = 0; 67 char c; 68 int digit; 69 70 while ((c = *str) != '\0') { 71 if (c >= '0' && c <= '9') 72 digit = c - '0'; 73 else if (c >= 'a' && c <= 'f') 74 digit = 10 + c - 'a'; 75 else 76 break; 77 78 val *= 16; 79 val += digit; 80 81 str++; 82 } 83 84 *nptr = str; 85 86 return (val); 87 } 88 89 /* 90 * Convert a bookmark to a string. 91 */ 92 static void 93 bookmark_to_name(zbookmark_t *zb, char *buf, size_t len) 94 { 95 (void) snprintf(buf, len, "%llx:%llx:%llx:%llx", 96 (u_longlong_t)zb->zb_objset, (u_longlong_t)zb->zb_object, 97 (u_longlong_t)zb->zb_level, (u_longlong_t)zb->zb_blkid); 98 } 99 100 /* 101 * Convert a string to a bookmark 102 */ 103 static void 104 name_to_bookmark(char *buf, zbookmark_t *zb) 105 { 106 zb->zb_objset = strtonum(buf, &buf); 107 ASSERT(*buf == ':'); 108 zb->zb_object = strtonum(buf + 1, &buf); 109 ASSERT(*buf == ':'); 110 zb->zb_level = (int)strtonum(buf + 1, &buf); 111 ASSERT(*buf == ':'); 112 zb->zb_blkid = strtonum(buf + 1, &buf); 113 ASSERT(*buf == '\0'); 114 } 115 116 /* 117 * Log an uncorrectable error to the persistent error log. We add it to the 118 * spa's list of pending errors. The changes are actually synced out to disk 119 * during spa_errlog_sync(). 120 */ 121 void 122 spa_log_error(spa_t *spa, zio_t *zio) 123 { 124 zbookmark_t *zb = &zio->io_logical->io_bookmark; 125 spa_error_entry_t search; 126 spa_error_entry_t *new; 127 avl_tree_t *tree; 128 avl_index_t where; 129 130 /* 131 * If we are trying to import a pool, ignore any errors, as we won't be 132 * writing to the pool any time soon. 133 */ 134 if (spa->spa_load_state == SPA_LOAD_TRYIMPORT) 135 return; 136 137 mutex_enter(&spa->spa_errlist_lock); 138 139 /* 140 * If we have had a request to rotate the log, log it to the next list 141 * instead of the current one. 142 */ 143 if (spa->spa_scrub_active || spa->spa_scrub_finished) 144 tree = &spa->spa_errlist_scrub; 145 else 146 tree = &spa->spa_errlist_last; 147 148 search.se_bookmark = *zb; 149 if (avl_find(tree, &search, &where) != NULL) { 150 mutex_exit(&spa->spa_errlist_lock); 151 return; 152 } 153 154 new = kmem_zalloc(sizeof (spa_error_entry_t), KM_SLEEP); 155 new->se_bookmark = *zb; 156 avl_insert(tree, new, where); 157 158 mutex_exit(&spa->spa_errlist_lock); 159 } 160 161 /* 162 * Return the number of errors currently in the error log. This is actually the 163 * sum of both the last log and the current log, since we don't know the union 164 * of these logs until we reach userland. 165 */ 166 uint64_t 167 spa_get_errlog_size(spa_t *spa) 168 { 169 uint64_t total = 0, count; 170 171 mutex_enter(&spa->spa_errlog_lock); 172 if (spa->spa_errlog_scrub != 0 && 173 zap_count(spa->spa_meta_objset, spa->spa_errlog_scrub, 174 &count) == 0) 175 total += count; 176 177 if (spa->spa_errlog_last != 0 && !spa->spa_scrub_finished && 178 zap_count(spa->spa_meta_objset, spa->spa_errlog_last, 179 &count) == 0) 180 total += count; 181 mutex_exit(&spa->spa_errlog_lock); 182 183 mutex_enter(&spa->spa_errlist_lock); 184 total += avl_numnodes(&spa->spa_errlist_last); 185 total += avl_numnodes(&spa->spa_errlist_scrub); 186 mutex_exit(&spa->spa_errlist_lock); 187 188 return (total); 189 } 190 191 #ifdef _KERNEL 192 static int 193 process_error_log(spa_t *spa, uint64_t obj, void *addr, size_t *count) 194 { 195 zap_cursor_t zc; 196 zap_attribute_t za; 197 zbookmark_t zb; 198 199 if (obj == 0) 200 return (0); 201 202 for (zap_cursor_init(&zc, spa->spa_meta_objset, obj); 203 zap_cursor_retrieve(&zc, &za) == 0; 204 zap_cursor_advance(&zc)) { 205 206 if (*count == 0) { 207 zap_cursor_fini(&zc); 208 return (ENOMEM); 209 } 210 211 name_to_bookmark(za.za_name, &zb); 212 213 if (copyout(&zb, (char *)addr + 214 (*count - 1) * sizeof (zbookmark_t), 215 sizeof (zbookmark_t)) != 0) 216 return (EFAULT); 217 218 *count -= 1; 219 } 220 221 zap_cursor_fini(&zc); 222 223 return (0); 224 } 225 226 static int 227 process_error_list(avl_tree_t *list, void *addr, size_t *count) 228 { 229 spa_error_entry_t *se; 230 231 for (se = avl_first(list); se != NULL; se = AVL_NEXT(list, se)) { 232 233 if (*count == 0) 234 return (ENOMEM); 235 236 if (copyout(&se->se_bookmark, (char *)addr + 237 (*count - 1) * sizeof (zbookmark_t), 238 sizeof (zbookmark_t)) != 0) 239 return (EFAULT); 240 241 *count -= 1; 242 } 243 244 return (0); 245 } 246 #endif 247 248 /* 249 * Copy all known errors to userland as an array of bookmarks. This is 250 * actually a union of the on-disk last log and current log, as well as any 251 * pending error requests. 252 * 253 * Because the act of reading the on-disk log could cause errors to be 254 * generated, we have two separate locks: one for the error log and one for the 255 * in-core error lists. We only need the error list lock to log and error, so 256 * we grab the error log lock while we read the on-disk logs, and only pick up 257 * the error list lock when we are finished. 258 */ 259 int 260 spa_get_errlog(spa_t *spa, void *uaddr, size_t *count) 261 { 262 int ret = 0; 263 264 #ifdef _KERNEL 265 mutex_enter(&spa->spa_errlog_lock); 266 267 ret = process_error_log(spa, spa->spa_errlog_scrub, uaddr, count); 268 269 if (!ret && !spa->spa_scrub_finished) 270 ret = process_error_log(spa, spa->spa_errlog_last, uaddr, 271 count); 272 273 mutex_enter(&spa->spa_errlist_lock); 274 if (!ret) 275 ret = process_error_list(&spa->spa_errlist_scrub, uaddr, 276 count); 277 if (!ret) 278 ret = process_error_list(&spa->spa_errlist_last, uaddr, 279 count); 280 mutex_exit(&spa->spa_errlist_lock); 281 282 mutex_exit(&spa->spa_errlog_lock); 283 #endif 284 285 return (ret); 286 } 287 288 /* 289 * Called when a scrub completes. This simply set a bit which tells which AVL 290 * tree to add new errors. spa_errlog_sync() is responsible for actually 291 * syncing the changes to the underlying objects. 292 */ 293 void 294 spa_errlog_rotate(spa_t *spa) 295 { 296 mutex_enter(&spa->spa_errlist_lock); 297 298 ASSERT(!spa->spa_scrub_finished); 299 spa->spa_scrub_finished = B_TRUE; 300 301 mutex_exit(&spa->spa_errlist_lock); 302 } 303 304 /* 305 * Discard any pending errors from the spa_t. Called when unloading a faulted 306 * pool, as the errors encountered during the open cannot be synced to disk. 307 */ 308 void 309 spa_errlog_drain(spa_t *spa) 310 { 311 spa_error_entry_t *se; 312 void *cookie; 313 314 mutex_enter(&spa->spa_errlist_lock); 315 316 cookie = NULL; 317 while ((se = avl_destroy_nodes(&spa->spa_errlist_last, 318 &cookie)) != NULL) 319 kmem_free(se, sizeof (spa_error_entry_t)); 320 cookie = NULL; 321 while ((se = avl_destroy_nodes(&spa->spa_errlist_scrub, 322 &cookie)) != NULL) 323 kmem_free(se, sizeof (spa_error_entry_t)); 324 325 mutex_exit(&spa->spa_errlist_lock); 326 } 327 328 /* 329 * Process a list of errors into the current on-disk log. 330 */ 331 static void 332 sync_error_list(spa_t *spa, avl_tree_t *t, uint64_t *obj, dmu_tx_t *tx) 333 { 334 spa_error_entry_t *se; 335 char buf[64]; 336 void *cookie; 337 338 if (avl_numnodes(t) != 0) { 339 /* create log if necessary */ 340 if (*obj == 0) 341 *obj = zap_create(spa->spa_meta_objset, 342 DMU_OT_ERROR_LOG, DMU_OT_NONE, 343 0, tx); 344 345 /* add errors to the current log */ 346 for (se = avl_first(t); se != NULL; se = AVL_NEXT(t, se)) { 347 char *name = se->se_name ? se->se_name : ""; 348 349 bookmark_to_name(&se->se_bookmark, buf, sizeof (buf)); 350 351 (void) zap_update(spa->spa_meta_objset, 352 *obj, buf, 1, strlen(name) + 1, name, tx); 353 } 354 355 /* purge the error list */ 356 cookie = NULL; 357 while ((se = avl_destroy_nodes(t, &cookie)) != NULL) 358 kmem_free(se, sizeof (spa_error_entry_t)); 359 } 360 } 361 362 /* 363 * Sync the error log out to disk. This is a little tricky because the act of 364 * writing the error log requires the spa_errlist_lock. So, we need to lock the 365 * error lists, take a copy of the lists, and then reinitialize them. Then, we 366 * drop the error list lock and take the error log lock, at which point we 367 * do the errlog processing. Then, if we encounter an I/O error during this 368 * process, we can successfully add the error to the list. Note that this will 369 * result in the perpetual recycling of errors, but it is an unlikely situation 370 * and not a performance critical operation. 371 */ 372 void 373 spa_errlog_sync(spa_t *spa, uint64_t txg) 374 { 375 dmu_tx_t *tx; 376 avl_tree_t scrub, last; 377 int scrub_finished; 378 379 mutex_enter(&spa->spa_errlist_lock); 380 381 /* 382 * Bail out early under normal circumstances. 383 */ 384 if (avl_numnodes(&spa->spa_errlist_scrub) == 0 && 385 avl_numnodes(&spa->spa_errlist_last) == 0 && 386 !spa->spa_scrub_finished) { 387 mutex_exit(&spa->spa_errlist_lock); 388 return; 389 } 390 391 spa_get_errlists(spa, &last, &scrub); 392 scrub_finished = spa->spa_scrub_finished; 393 spa->spa_scrub_finished = B_FALSE; 394 395 mutex_exit(&spa->spa_errlist_lock); 396 mutex_enter(&spa->spa_errlog_lock); 397 398 tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg); 399 400 /* 401 * Sync out the current list of errors. 402 */ 403 sync_error_list(spa, &last, &spa->spa_errlog_last, tx); 404 405 /* 406 * Rotate the log if necessary. 407 */ 408 if (scrub_finished) { 409 if (spa->spa_errlog_last != 0) 410 VERIFY(dmu_object_free(spa->spa_meta_objset, 411 spa->spa_errlog_last, tx) == 0); 412 spa->spa_errlog_last = spa->spa_errlog_scrub; 413 spa->spa_errlog_scrub = 0; 414 415 sync_error_list(spa, &scrub, &spa->spa_errlog_last, tx); 416 } 417 418 /* 419 * Sync out any pending scrub errors. 420 */ 421 sync_error_list(spa, &scrub, &spa->spa_errlog_scrub, tx); 422 423 /* 424 * Update the MOS to reflect the new values. 425 */ 426 (void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT, 427 DMU_POOL_ERRLOG_LAST, sizeof (uint64_t), 1, 428 &spa->spa_errlog_last, tx); 429 (void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT, 430 DMU_POOL_ERRLOG_SCRUB, sizeof (uint64_t), 1, 431 &spa->spa_errlog_scrub, tx); 432 433 dmu_tx_commit(tx); 434 435 mutex_exit(&spa->spa_errlog_lock); 436 } 437