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 #ifdef _KERNEL 62 uint64_t 63 strtonum(const char *str, char **nptr) 64 { 65 uint64_t val = 0; 66 char c; 67 int digit; 68 69 while ((c = *str) != '\0') { 70 if (c >= '0' && c <= '9') 71 digit = c - '0'; 72 else if (c >= 'a' && c <= 'f') 73 digit = 10 + c - 'a'; 74 else 75 break; 76 77 val *= 16; 78 val += digit; 79 80 str++; 81 } 82 83 if (nptr) 84 *nptr = (char *)str; 85 86 return (val); 87 } 88 #endif 89 90 /* 91 * Convert a bookmark to a string. 92 */ 93 static void 94 bookmark_to_name(zbookmark_t *zb, char *buf, size_t len) 95 { 96 (void) snprintf(buf, len, "%llx:%llx:%llx:%llx", 97 (u_longlong_t)zb->zb_objset, (u_longlong_t)zb->zb_object, 98 (u_longlong_t)zb->zb_level, (u_longlong_t)zb->zb_blkid); 99 } 100 101 /* 102 * Convert a string to a bookmark 103 */ 104 #ifdef _KERNEL 105 static void 106 name_to_bookmark(char *buf, zbookmark_t *zb) 107 { 108 zb->zb_objset = strtonum(buf, &buf); 109 ASSERT(*buf == ':'); 110 zb->zb_object = strtonum(buf + 1, &buf); 111 ASSERT(*buf == ':'); 112 zb->zb_level = (int)strtonum(buf + 1, &buf); 113 ASSERT(*buf == ':'); 114 zb->zb_blkid = strtonum(buf + 1, &buf); 115 ASSERT(*buf == '\0'); 116 } 117 #endif 118 119 /* 120 * Log an uncorrectable error to the persistent error log. We add it to the 121 * spa's list of pending errors. The changes are actually synced out to disk 122 * during spa_errlog_sync(). 123 */ 124 void 125 spa_log_error(spa_t *spa, zio_t *zio) 126 { 127 zbookmark_t *zb = &zio->io_logical->io_bookmark; 128 spa_error_entry_t search; 129 spa_error_entry_t *new; 130 avl_tree_t *tree; 131 avl_index_t where; 132 133 /* 134 * If we are trying to import a pool, ignore any errors, as we won't be 135 * writing to the pool any time soon. 136 */ 137 if (spa->spa_load_state == SPA_LOAD_TRYIMPORT) 138 return; 139 140 mutex_enter(&spa->spa_errlist_lock); 141 142 /* 143 * If we have had a request to rotate the log, log it to the next list 144 * instead of the current one. 145 */ 146 if (spa->spa_scrub_active || spa->spa_scrub_finished) 147 tree = &spa->spa_errlist_scrub; 148 else 149 tree = &spa->spa_errlist_last; 150 151 search.se_bookmark = *zb; 152 if (avl_find(tree, &search, &where) != NULL) { 153 mutex_exit(&spa->spa_errlist_lock); 154 return; 155 } 156 157 new = kmem_zalloc(sizeof (spa_error_entry_t), KM_SLEEP); 158 new->se_bookmark = *zb; 159 avl_insert(tree, new, where); 160 161 mutex_exit(&spa->spa_errlist_lock); 162 } 163 164 /* 165 * Return the number of errors currently in the error log. This is actually the 166 * sum of both the last log and the current log, since we don't know the union 167 * of these logs until we reach userland. 168 */ 169 uint64_t 170 spa_get_errlog_size(spa_t *spa) 171 { 172 uint64_t total = 0, count; 173 174 mutex_enter(&spa->spa_errlog_lock); 175 if (spa->spa_errlog_scrub != 0 && 176 zap_count(spa->spa_meta_objset, spa->spa_errlog_scrub, 177 &count) == 0) 178 total += count; 179 180 if (spa->spa_errlog_last != 0 && !spa->spa_scrub_finished && 181 zap_count(spa->spa_meta_objset, spa->spa_errlog_last, 182 &count) == 0) 183 total += count; 184 mutex_exit(&spa->spa_errlog_lock); 185 186 mutex_enter(&spa->spa_errlist_lock); 187 total += avl_numnodes(&spa->spa_errlist_last); 188 total += avl_numnodes(&spa->spa_errlist_scrub); 189 mutex_exit(&spa->spa_errlist_lock); 190 191 return (total); 192 } 193 194 #ifdef _KERNEL 195 static int 196 process_error_log(spa_t *spa, uint64_t obj, void *addr, size_t *count) 197 { 198 zap_cursor_t zc; 199 zap_attribute_t za; 200 zbookmark_t zb; 201 202 if (obj == 0) 203 return (0); 204 205 for (zap_cursor_init(&zc, spa->spa_meta_objset, obj); 206 zap_cursor_retrieve(&zc, &za) == 0; 207 zap_cursor_advance(&zc)) { 208 209 if (*count == 0) { 210 zap_cursor_fini(&zc); 211 return (ENOMEM); 212 } 213 214 name_to_bookmark(za.za_name, &zb); 215 216 if (copyout(&zb, (char *)addr + 217 (*count - 1) * sizeof (zbookmark_t), 218 sizeof (zbookmark_t)) != 0) 219 return (EFAULT); 220 221 *count -= 1; 222 } 223 224 zap_cursor_fini(&zc); 225 226 return (0); 227 } 228 229 static int 230 process_error_list(avl_tree_t *list, void *addr, size_t *count) 231 { 232 spa_error_entry_t *se; 233 234 for (se = avl_first(list); se != NULL; se = AVL_NEXT(list, se)) { 235 236 if (*count == 0) 237 return (ENOMEM); 238 239 if (copyout(&se->se_bookmark, (char *)addr + 240 (*count - 1) * sizeof (zbookmark_t), 241 sizeof (zbookmark_t)) != 0) 242 return (EFAULT); 243 244 *count -= 1; 245 } 246 247 return (0); 248 } 249 #endif 250 251 /* 252 * Copy all known errors to userland as an array of bookmarks. This is 253 * actually a union of the on-disk last log and current log, as well as any 254 * pending error requests. 255 * 256 * Because the act of reading the on-disk log could cause errors to be 257 * generated, we have two separate locks: one for the error log and one for the 258 * in-core error lists. We only need the error list lock to log and error, so 259 * we grab the error log lock while we read the on-disk logs, and only pick up 260 * the error list lock when we are finished. 261 */ 262 int 263 spa_get_errlog(spa_t *spa, void *uaddr, size_t *count) 264 { 265 int ret = 0; 266 267 #ifdef _KERNEL 268 mutex_enter(&spa->spa_errlog_lock); 269 270 ret = process_error_log(spa, spa->spa_errlog_scrub, uaddr, count); 271 272 if (!ret && !spa->spa_scrub_finished) 273 ret = process_error_log(spa, spa->spa_errlog_last, uaddr, 274 count); 275 276 mutex_enter(&spa->spa_errlist_lock); 277 if (!ret) 278 ret = process_error_list(&spa->spa_errlist_scrub, uaddr, 279 count); 280 if (!ret) 281 ret = process_error_list(&spa->spa_errlist_last, uaddr, 282 count); 283 mutex_exit(&spa->spa_errlist_lock); 284 285 mutex_exit(&spa->spa_errlog_lock); 286 #endif 287 288 return (ret); 289 } 290 291 /* 292 * Called when a scrub completes. This simply set a bit which tells which AVL 293 * tree to add new errors. spa_errlog_sync() is responsible for actually 294 * syncing the changes to the underlying objects. 295 */ 296 void 297 spa_errlog_rotate(spa_t *spa) 298 { 299 mutex_enter(&spa->spa_errlist_lock); 300 spa->spa_scrub_finished = B_TRUE; 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