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 2008 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 #ifdef _KERNEL 64 static uint64_t 65 strtonum(char *str, char **nptr) 66 { 67 uint64_t val = 0; 68 char c; 69 int digit; 70 71 while ((c = *str) != '\0') { 72 if (c >= '0' && c <= '9') 73 digit = c - '0'; 74 else if (c >= 'a' && c <= 'f') 75 digit = 10 + c - 'a'; 76 else 77 break; 78 79 val *= 16; 80 val += digit; 81 82 str++; 83 } 84 85 *nptr = str; 86 87 return (val); 88 } 89 #endif 90 91 /* 92 * Convert a bookmark to a string. 93 */ 94 static void 95 bookmark_to_name(zbookmark_t *zb, char *buf, size_t len) 96 { 97 (void) snprintf(buf, len, "%llx:%llx:%llx:%llx", 98 (u_longlong_t)zb->zb_objset, (u_longlong_t)zb->zb_object, 99 (u_longlong_t)zb->zb_level, (u_longlong_t)zb->zb_blkid); 100 } 101 102 /* 103 * Convert a string to a bookmark 104 */ 105 #ifdef _KERNEL 106 static void 107 name_to_bookmark(char *buf, zbookmark_t *zb) 108 { 109 zb->zb_objset = strtonum(buf, &buf); 110 ASSERT(*buf == ':'); 111 zb->zb_object = strtonum(buf + 1, &buf); 112 ASSERT(*buf == ':'); 113 zb->zb_level = (int)strtonum(buf + 1, &buf); 114 ASSERT(*buf == ':'); 115 zb->zb_blkid = strtonum(buf + 1, &buf); 116 ASSERT(*buf == '\0'); 117 } 118 #endif 119 120 /* 121 * Log an uncorrectable error to the persistent error log. We add it to the 122 * spa's list of pending errors. The changes are actually synced out to disk 123 * during spa_errlog_sync(). 124 */ 125 void 126 spa_log_error(spa_t *spa, zio_t *zio) 127 { 128 zbookmark_t *zb = &zio->io_logical->io_bookmark; 129 spa_error_entry_t search; 130 spa_error_entry_t *new; 131 avl_tree_t *tree; 132 avl_index_t where; 133 134 /* 135 * If we are trying to import a pool, ignore any errors, as we won't be 136 * writing to the pool any time soon. 137 */ 138 if (spa->spa_load_state == SPA_LOAD_TRYIMPORT) 139 return; 140 141 mutex_enter(&spa->spa_errlist_lock); 142 143 /* 144 * If we have had a request to rotate the log, log it to the next list 145 * instead of the current one. 146 */ 147 if (spa->spa_scrub_active || spa->spa_scrub_finished) 148 tree = &spa->spa_errlist_scrub; 149 else 150 tree = &spa->spa_errlist_last; 151 152 search.se_bookmark = *zb; 153 if (avl_find(tree, &search, &where) != NULL) { 154 mutex_exit(&spa->spa_errlist_lock); 155 return; 156 } 157 158 new = kmem_zalloc(sizeof (spa_error_entry_t), KM_SLEEP); 159 new->se_bookmark = *zb; 160 avl_insert(tree, new, where); 161 162 mutex_exit(&spa->spa_errlist_lock); 163 } 164 165 /* 166 * Return the number of errors currently in the error log. This is actually the 167 * sum of both the last log and the current log, since we don't know the union 168 * of these logs until we reach userland. 169 */ 170 uint64_t 171 spa_get_errlog_size(spa_t *spa) 172 { 173 uint64_t total = 0, count; 174 175 mutex_enter(&spa->spa_errlog_lock); 176 if (spa->spa_errlog_scrub != 0 && 177 zap_count(spa->spa_meta_objset, spa->spa_errlog_scrub, 178 &count) == 0) 179 total += count; 180 181 if (spa->spa_errlog_last != 0 && !spa->spa_scrub_finished && 182 zap_count(spa->spa_meta_objset, spa->spa_errlog_last, 183 &count) == 0) 184 total += count; 185 mutex_exit(&spa->spa_errlog_lock); 186 187 mutex_enter(&spa->spa_errlist_lock); 188 total += avl_numnodes(&spa->spa_errlist_last); 189 total += avl_numnodes(&spa->spa_errlist_scrub); 190 mutex_exit(&spa->spa_errlist_lock); 191 192 return (total); 193 } 194 195 #ifdef _KERNEL 196 static int 197 process_error_log(spa_t *spa, uint64_t obj, void *addr, size_t *count) 198 { 199 zap_cursor_t zc; 200 zap_attribute_t za; 201 zbookmark_t zb; 202 203 if (obj == 0) 204 return (0); 205 206 for (zap_cursor_init(&zc, spa->spa_meta_objset, obj); 207 zap_cursor_retrieve(&zc, &za) == 0; 208 zap_cursor_advance(&zc)) { 209 210 if (*count == 0) { 211 zap_cursor_fini(&zc); 212 return (ENOMEM); 213 } 214 215 name_to_bookmark(za.za_name, &zb); 216 217 if (copyout(&zb, (char *)addr + 218 (*count - 1) * sizeof (zbookmark_t), 219 sizeof (zbookmark_t)) != 0) 220 return (EFAULT); 221 222 *count -= 1; 223 } 224 225 zap_cursor_fini(&zc); 226 227 return (0); 228 } 229 230 static int 231 process_error_list(avl_tree_t *list, void *addr, size_t *count) 232 { 233 spa_error_entry_t *se; 234 235 for (se = avl_first(list); se != NULL; se = AVL_NEXT(list, se)) { 236 237 if (*count == 0) 238 return (ENOMEM); 239 240 if (copyout(&se->se_bookmark, (char *)addr + 241 (*count - 1) * sizeof (zbookmark_t), 242 sizeof (zbookmark_t)) != 0) 243 return (EFAULT); 244 245 *count -= 1; 246 } 247 248 return (0); 249 } 250 #endif 251 252 /* 253 * Copy all known errors to userland as an array of bookmarks. This is 254 * actually a union of the on-disk last log and current log, as well as any 255 * pending error requests. 256 * 257 * Because the act of reading the on-disk log could cause errors to be 258 * generated, we have two separate locks: one for the error log and one for the 259 * in-core error lists. We only need the error list lock to log and error, so 260 * we grab the error log lock while we read the on-disk logs, and only pick up 261 * the error list lock when we are finished. 262 */ 263 int 264 spa_get_errlog(spa_t *spa, void *uaddr, size_t *count) 265 { 266 int ret = 0; 267 268 #ifdef _KERNEL 269 mutex_enter(&spa->spa_errlog_lock); 270 271 ret = process_error_log(spa, spa->spa_errlog_scrub, uaddr, count); 272 273 if (!ret && !spa->spa_scrub_finished) 274 ret = process_error_log(spa, spa->spa_errlog_last, uaddr, 275 count); 276 277 mutex_enter(&spa->spa_errlist_lock); 278 if (!ret) 279 ret = process_error_list(&spa->spa_errlist_scrub, uaddr, 280 count); 281 if (!ret) 282 ret = process_error_list(&spa->spa_errlist_last, uaddr, 283 count); 284 mutex_exit(&spa->spa_errlist_lock); 285 286 mutex_exit(&spa->spa_errlog_lock); 287 #endif 288 289 return (ret); 290 } 291 292 /* 293 * Called when a scrub completes. This simply set a bit which tells which AVL 294 * tree to add new errors. spa_errlog_sync() is responsible for actually 295 * syncing the changes to the underlying objects. 296 */ 297 void 298 spa_errlog_rotate(spa_t *spa) 299 { 300 mutex_enter(&spa->spa_errlist_lock); 301 spa->spa_scrub_finished = B_TRUE; 302 mutex_exit(&spa->spa_errlist_lock); 303 } 304 305 /* 306 * Discard any pending errors from the spa_t. Called when unloading a faulted 307 * pool, as the errors encountered during the open cannot be synced to disk. 308 */ 309 void 310 spa_errlog_drain(spa_t *spa) 311 { 312 spa_error_entry_t *se; 313 void *cookie; 314 315 mutex_enter(&spa->spa_errlist_lock); 316 317 cookie = NULL; 318 while ((se = avl_destroy_nodes(&spa->spa_errlist_last, 319 &cookie)) != NULL) 320 kmem_free(se, sizeof (spa_error_entry_t)); 321 cookie = NULL; 322 while ((se = avl_destroy_nodes(&spa->spa_errlist_scrub, 323 &cookie)) != NULL) 324 kmem_free(se, sizeof (spa_error_entry_t)); 325 326 mutex_exit(&spa->spa_errlist_lock); 327 } 328 329 /* 330 * Process a list of errors into the current on-disk log. 331 */ 332 static void 333 sync_error_list(spa_t *spa, avl_tree_t *t, uint64_t *obj, dmu_tx_t *tx) 334 { 335 spa_error_entry_t *se; 336 char buf[64]; 337 void *cookie; 338 339 if (avl_numnodes(t) != 0) { 340 /* create log if necessary */ 341 if (*obj == 0) 342 *obj = zap_create(spa->spa_meta_objset, 343 DMU_OT_ERROR_LOG, DMU_OT_NONE, 344 0, tx); 345 346 /* add errors to the current log */ 347 for (se = avl_first(t); se != NULL; se = AVL_NEXT(t, se)) { 348 char *name = se->se_name ? se->se_name : ""; 349 350 bookmark_to_name(&se->se_bookmark, buf, sizeof (buf)); 351 352 (void) zap_update(spa->spa_meta_objset, 353 *obj, buf, 1, strlen(name) + 1, name, tx); 354 } 355 356 /* purge the error list */ 357 cookie = NULL; 358 while ((se = avl_destroy_nodes(t, &cookie)) != NULL) 359 kmem_free(se, sizeof (spa_error_entry_t)); 360 } 361 } 362 363 /* 364 * Sync the error log out to disk. This is a little tricky because the act of 365 * writing the error log requires the spa_errlist_lock. So, we need to lock the 366 * error lists, take a copy of the lists, and then reinitialize them. Then, we 367 * drop the error list lock and take the error log lock, at which point we 368 * do the errlog processing. Then, if we encounter an I/O error during this 369 * process, we can successfully add the error to the list. Note that this will 370 * result in the perpetual recycling of errors, but it is an unlikely situation 371 * and not a performance critical operation. 372 */ 373 void 374 spa_errlog_sync(spa_t *spa, uint64_t txg) 375 { 376 dmu_tx_t *tx; 377 avl_tree_t scrub, last; 378 int scrub_finished; 379 380 mutex_enter(&spa->spa_errlist_lock); 381 382 /* 383 * Bail out early under normal circumstances. 384 */ 385 if (avl_numnodes(&spa->spa_errlist_scrub) == 0 && 386 avl_numnodes(&spa->spa_errlist_last) == 0 && 387 !spa->spa_scrub_finished) { 388 mutex_exit(&spa->spa_errlist_lock); 389 return; 390 } 391 392 spa_get_errlists(spa, &last, &scrub); 393 scrub_finished = spa->spa_scrub_finished; 394 spa->spa_scrub_finished = B_FALSE; 395 396 mutex_exit(&spa->spa_errlist_lock); 397 mutex_enter(&spa->spa_errlog_lock); 398 399 tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg); 400 401 /* 402 * Sync out the current list of errors. 403 */ 404 sync_error_list(spa, &last, &spa->spa_errlog_last, tx); 405 406 /* 407 * Rotate the log if necessary. 408 */ 409 if (scrub_finished) { 410 if (spa->spa_errlog_last != 0) 411 VERIFY(dmu_object_free(spa->spa_meta_objset, 412 spa->spa_errlog_last, tx) == 0); 413 spa->spa_errlog_last = spa->spa_errlog_scrub; 414 spa->spa_errlog_scrub = 0; 415 416 sync_error_list(spa, &scrub, &spa->spa_errlog_last, tx); 417 } 418 419 /* 420 * Sync out any pending scrub errors. 421 */ 422 sync_error_list(spa, &scrub, &spa->spa_errlog_scrub, tx); 423 424 /* 425 * Update the MOS to reflect the new values. 426 */ 427 (void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT, 428 DMU_POOL_ERRLOG_LAST, sizeof (uint64_t), 1, 429 &spa->spa_errlog_last, tx); 430 (void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT, 431 DMU_POOL_ERRLOG_SCRUB, sizeof (uint64_t), 1, 432 &spa->spa_errlog_scrub, tx); 433 434 dmu_tx_commit(tx); 435 436 mutex_exit(&spa->spa_errlog_lock); 437 } 438