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 2009 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26 /* 27 * Routines to manage the on-disk persistent error log. 28 * 29 * Each pool stores a log of all logical data errors seen during normal 30 * operation. This is actually the union of two distinct logs: the last log, 31 * and the current log. All errors seen are logged to the current log. When a 32 * scrub completes, the current log becomes the last log, the last log is thrown 33 * out, and the current log is reinitialized. This way, if an error is somehow 34 * corrected, a new scrub will show that that it no longer exists, and will be 35 * deleted from the log when the scrub completes. 36 * 37 * The log is stored using a ZAP object whose key is a string form of the 38 * zbookmark tuple (objset, object, level, blkid), and whose contents is an 39 * optional 'objset:object' human-readable string describing the data. When an 40 * error is first logged, this string will be empty, indicating that no name is 41 * known. This prevents us from having to issue a potentially large amount of 42 * I/O to discover the object name during an error path. Instead, we do the 43 * calculation when the data is requested, storing the result so future queries 44 * will be faster. 45 * 46 * This log is then shipped into an nvlist where the key is the dataset name and 47 * the value is the object name. Userland is then responsible for uniquifying 48 * this list and displaying it to the user. 49 */ 50 51 #include <sys/dmu_tx.h> 52 #include <sys/spa.h> 53 #include <sys/spa_impl.h> 54 #include <sys/zap.h> 55 #include <sys/zio.h> 56 57 /* 58 * This is a stripped-down version of strtoull, suitable only for converting 59 * lowercase hexidecimal numbers that don't overflow. 60 */ 61 uint64_t 62 strtonum(const char *str, char **nptr) 63 { 64 uint64_t val = 0; 65 char c; 66 int digit; 67 68 while ((c = *str) != '\0') { 69 if (c >= '0' && c <= '9') 70 digit = c - '0'; 71 else if (c >= 'a' && c <= 'f') 72 digit = 10 + c - 'a'; 73 else 74 break; 75 76 val *= 16; 77 val += digit; 78 79 str++; 80 } 81 82 if (nptr) 83 *nptr = (char *)str; 84 85 return (val); 86 } 87 88 /* 89 * Convert a bookmark to a string. 90 */ 91 static void 92 bookmark_to_name(zbookmark_t *zb, char *buf, size_t len) 93 { 94 (void) snprintf(buf, len, "%llx:%llx:%llx:%llx", 95 (u_longlong_t)zb->zb_objset, (u_longlong_t)zb->zb_object, 96 (u_longlong_t)zb->zb_level, (u_longlong_t)zb->zb_blkid); 97 } 98 99 /* 100 * Convert a string to a bookmark 101 */ 102 #ifdef _KERNEL 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 #endif 116 117 /* 118 * Log an uncorrectable error to the persistent error log. We add it to the 119 * spa's list of pending errors. The changes are actually synced out to disk 120 * during spa_errlog_sync(). 121 */ 122 void 123 spa_log_error(spa_t *spa, zio_t *zio) 124 { 125 zbookmark_t *zb = &zio->io_logical->io_bookmark; 126 spa_error_entry_t search; 127 spa_error_entry_t *new; 128 avl_tree_t *tree; 129 avl_index_t where; 130 131 /* 132 * If we are trying to import a pool, ignore any errors, as we won't be 133 * writing to the pool any time soon. 134 */ 135 if (spa->spa_load_state == SPA_LOAD_TRYIMPORT) 136 return; 137 138 mutex_enter(&spa->spa_errlist_lock); 139 140 /* 141 * If we have had a request to rotate the log, log it to the next list 142 * instead of the current one. 143 */ 144 if (spa->spa_scrub_active || spa->spa_scrub_finished) 145 tree = &spa->spa_errlist_scrub; 146 else 147 tree = &spa->spa_errlist_last; 148 149 search.se_bookmark = *zb; 150 if (avl_find(tree, &search, &where) != NULL) { 151 mutex_exit(&spa->spa_errlist_lock); 152 return; 153 } 154 155 new = kmem_zalloc(sizeof (spa_error_entry_t), KM_SLEEP); 156 new->se_bookmark = *zb; 157 avl_insert(tree, new, where); 158 159 mutex_exit(&spa->spa_errlist_lock); 160 } 161 162 /* 163 * Return the number of errors currently in the error log. This is actually the 164 * sum of both the last log and the current log, since we don't know the union 165 * of these logs until we reach userland. 166 */ 167 uint64_t 168 spa_get_errlog_size(spa_t *spa) 169 { 170 uint64_t total = 0, count; 171 172 mutex_enter(&spa->spa_errlog_lock); 173 if (spa->spa_errlog_scrub != 0 && 174 zap_count(spa->spa_meta_objset, spa->spa_errlog_scrub, 175 &count) == 0) 176 total += count; 177 178 if (spa->spa_errlog_last != 0 && !spa->spa_scrub_finished && 179 zap_count(spa->spa_meta_objset, spa->spa_errlog_last, 180 &count) == 0) 181 total += count; 182 mutex_exit(&spa->spa_errlog_lock); 183 184 mutex_enter(&spa->spa_errlist_lock); 185 total += avl_numnodes(&spa->spa_errlist_last); 186 total += avl_numnodes(&spa->spa_errlist_scrub); 187 mutex_exit(&spa->spa_errlist_lock); 188 189 return (total); 190 } 191 192 #ifdef _KERNEL 193 static int 194 process_error_log(spa_t *spa, uint64_t obj, void *addr, size_t *count) 195 { 196 zap_cursor_t zc; 197 zap_attribute_t za; 198 zbookmark_t zb; 199 200 if (obj == 0) 201 return (0); 202 203 for (zap_cursor_init(&zc, spa->spa_meta_objset, obj); 204 zap_cursor_retrieve(&zc, &za) == 0; 205 zap_cursor_advance(&zc)) { 206 207 if (*count == 0) { 208 zap_cursor_fini(&zc); 209 return (ENOMEM); 210 } 211 212 name_to_bookmark(za.za_name, &zb); 213 214 if (copyout(&zb, (char *)addr + 215 (*count - 1) * sizeof (zbookmark_t), 216 sizeof (zbookmark_t)) != 0) 217 return (EFAULT); 218 219 *count -= 1; 220 } 221 222 zap_cursor_fini(&zc); 223 224 return (0); 225 } 226 227 static int 228 process_error_list(avl_tree_t *list, void *addr, size_t *count) 229 { 230 spa_error_entry_t *se; 231 232 for (se = avl_first(list); se != NULL; se = AVL_NEXT(list, se)) { 233 234 if (*count == 0) 235 return (ENOMEM); 236 237 if (copyout(&se->se_bookmark, (char *)addr + 238 (*count - 1) * sizeof (zbookmark_t), 239 sizeof (zbookmark_t)) != 0) 240 return (EFAULT); 241 242 *count -= 1; 243 } 244 245 return (0); 246 } 247 #endif 248 249 /* 250 * Copy all known errors to userland as an array of bookmarks. This is 251 * actually a union of the on-disk last log and current log, as well as any 252 * pending error requests. 253 * 254 * Because the act of reading the on-disk log could cause errors to be 255 * generated, we have two separate locks: one for the error log and one for the 256 * in-core error lists. We only need the error list lock to log and error, so 257 * we grab the error log lock while we read the on-disk logs, and only pick up 258 * the error list lock when we are finished. 259 */ 260 int 261 spa_get_errlog(spa_t *spa, void *uaddr, size_t *count) 262 { 263 int ret = 0; 264 265 #ifdef _KERNEL 266 mutex_enter(&spa->spa_errlog_lock); 267 268 ret = process_error_log(spa, spa->spa_errlog_scrub, uaddr, count); 269 270 if (!ret && !spa->spa_scrub_finished) 271 ret = process_error_log(spa, spa->spa_errlog_last, uaddr, 272 count); 273 274 mutex_enter(&spa->spa_errlist_lock); 275 if (!ret) 276 ret = process_error_list(&spa->spa_errlist_scrub, uaddr, 277 count); 278 if (!ret) 279 ret = process_error_list(&spa->spa_errlist_last, uaddr, 280 count); 281 mutex_exit(&spa->spa_errlist_lock); 282 283 mutex_exit(&spa->spa_errlog_lock); 284 #endif 285 286 return (ret); 287 } 288 289 /* 290 * Called when a scrub completes. This simply set a bit which tells which AVL 291 * tree to add new errors. spa_errlog_sync() is responsible for actually 292 * syncing the changes to the underlying objects. 293 */ 294 void 295 spa_errlog_rotate(spa_t *spa) 296 { 297 mutex_enter(&spa->spa_errlist_lock); 298 spa->spa_scrub_finished = B_TRUE; 299 mutex_exit(&spa->spa_errlist_lock); 300 } 301 302 /* 303 * Discard any pending errors from the spa_t. Called when unloading a faulted 304 * pool, as the errors encountered during the open cannot be synced to disk. 305 */ 306 void 307 spa_errlog_drain(spa_t *spa) 308 { 309 spa_error_entry_t *se; 310 void *cookie; 311 312 mutex_enter(&spa->spa_errlist_lock); 313 314 cookie = NULL; 315 while ((se = avl_destroy_nodes(&spa->spa_errlist_last, 316 &cookie)) != NULL) 317 kmem_free(se, sizeof (spa_error_entry_t)); 318 cookie = NULL; 319 while ((se = avl_destroy_nodes(&spa->spa_errlist_scrub, 320 &cookie)) != NULL) 321 kmem_free(se, sizeof (spa_error_entry_t)); 322 323 mutex_exit(&spa->spa_errlist_lock); 324 } 325 326 /* 327 * Process a list of errors into the current on-disk log. 328 */ 329 static void 330 sync_error_list(spa_t *spa, avl_tree_t *t, uint64_t *obj, dmu_tx_t *tx) 331 { 332 spa_error_entry_t *se; 333 char buf[64]; 334 void *cookie; 335 336 if (avl_numnodes(t) != 0) { 337 /* create log if necessary */ 338 if (*obj == 0) 339 *obj = zap_create(spa->spa_meta_objset, 340 DMU_OT_ERROR_LOG, DMU_OT_NONE, 341 0, tx); 342 343 /* add errors to the current log */ 344 for (se = avl_first(t); se != NULL; se = AVL_NEXT(t, se)) { 345 char *name = se->se_name ? se->se_name : ""; 346 347 bookmark_to_name(&se->se_bookmark, buf, sizeof (buf)); 348 349 (void) zap_update(spa->spa_meta_objset, 350 *obj, buf, 1, strlen(name) + 1, name, tx); 351 } 352 353 /* purge the error list */ 354 cookie = NULL; 355 while ((se = avl_destroy_nodes(t, &cookie)) != NULL) 356 kmem_free(se, sizeof (spa_error_entry_t)); 357 } 358 } 359 360 /* 361 * Sync the error log out to disk. This is a little tricky because the act of 362 * writing the error log requires the spa_errlist_lock. So, we need to lock the 363 * error lists, take a copy of the lists, and then reinitialize them. Then, we 364 * drop the error list lock and take the error log lock, at which point we 365 * do the errlog processing. Then, if we encounter an I/O error during this 366 * process, we can successfully add the error to the list. Note that this will 367 * result in the perpetual recycling of errors, but it is an unlikely situation 368 * and not a performance critical operation. 369 */ 370 void 371 spa_errlog_sync(spa_t *spa, uint64_t txg) 372 { 373 dmu_tx_t *tx; 374 avl_tree_t scrub, last; 375 int scrub_finished; 376 377 mutex_enter(&spa->spa_errlist_lock); 378 379 /* 380 * Bail out early under normal circumstances. 381 */ 382 if (avl_numnodes(&spa->spa_errlist_scrub) == 0 && 383 avl_numnodes(&spa->spa_errlist_last) == 0 && 384 !spa->spa_scrub_finished) { 385 mutex_exit(&spa->spa_errlist_lock); 386 return; 387 } 388 389 spa_get_errlists(spa, &last, &scrub); 390 scrub_finished = spa->spa_scrub_finished; 391 spa->spa_scrub_finished = B_FALSE; 392 393 mutex_exit(&spa->spa_errlist_lock); 394 mutex_enter(&spa->spa_errlog_lock); 395 396 tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg); 397 398 /* 399 * Sync out the current list of errors. 400 */ 401 sync_error_list(spa, &last, &spa->spa_errlog_last, tx); 402 403 /* 404 * Rotate the log if necessary. 405 */ 406 if (scrub_finished) { 407 if (spa->spa_errlog_last != 0) 408 VERIFY(dmu_object_free(spa->spa_meta_objset, 409 spa->spa_errlog_last, tx) == 0); 410 spa->spa_errlog_last = spa->spa_errlog_scrub; 411 spa->spa_errlog_scrub = 0; 412 413 sync_error_list(spa, &scrub, &spa->spa_errlog_last, tx); 414 } 415 416 /* 417 * Sync out any pending scrub errors. 418 */ 419 sync_error_list(spa, &scrub, &spa->spa_errlog_scrub, tx); 420 421 /* 422 * Update the MOS to reflect the new values. 423 */ 424 (void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT, 425 DMU_POOL_ERRLOG_LAST, sizeof (uint64_t), 1, 426 &spa->spa_errlog_last, tx); 427 (void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT, 428 DMU_POOL_ERRLOG_SCRUB, sizeof (uint64_t), 1, 429 &spa->spa_errlog_scrub, tx); 430 431 dmu_tx_commit(tx); 432 433 mutex_exit(&spa->spa_errlog_lock); 434 } 435