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 (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved. 23 */ 24 25 /* 26 * Routines to manage the on-disk persistent error log. 27 * 28 * Each pool stores a log of all logical data errors seen during normal 29 * operation. This is actually the union of two distinct logs: the last log, 30 * and the current log. All errors seen are logged to the current log. When a 31 * scrub completes, the current log becomes the last log, the last log is thrown 32 * out, and the current log is reinitialized. This way, if an error is somehow 33 * corrected, a new scrub will show that that it no longer exists, and will be 34 * deleted from the log when the scrub completes. 35 * 36 * The log is stored using a ZAP object whose key is a string form of the 37 * zbookmark tuple (objset, object, level, blkid), and whose contents is an 38 * optional 'objset:object' human-readable string describing the data. When an 39 * error is first logged, this string will be empty, indicating that no name is 40 * known. This prevents us from having to issue a potentially large amount of 41 * I/O to discover the object name during an error path. Instead, we do the 42 * calculation when the data is requested, storing the result so future queries 43 * will be faster. 44 * 45 * This log is then shipped into an nvlist where the key is the dataset name and 46 * the value is the object name. Userland is then responsible for uniquifying 47 * this list and displaying it to the user. 48 */ 49 50 #include <sys/dmu_tx.h> 51 #include <sys/spa.h> 52 #include <sys/spa_impl.h> 53 #include <sys/zap.h> 54 #include <sys/zio.h> 55 56 57 /* 58 * Convert a bookmark to a string. 59 */ 60 static void 61 bookmark_to_name(zbookmark_t *zb, char *buf, size_t len) 62 { 63 (void) snprintf(buf, len, "%llx:%llx:%llx:%llx", 64 (u_longlong_t)zb->zb_objset, (u_longlong_t)zb->zb_object, 65 (u_longlong_t)zb->zb_level, (u_longlong_t)zb->zb_blkid); 66 } 67 68 /* 69 * Convert a string to a bookmark 70 */ 71 #ifdef _KERNEL 72 static void 73 name_to_bookmark(char *buf, zbookmark_t *zb) 74 { 75 zb->zb_objset = strtonum(buf, &buf); 76 ASSERT(*buf == ':'); 77 zb->zb_object = strtonum(buf + 1, &buf); 78 ASSERT(*buf == ':'); 79 zb->zb_level = (int)strtonum(buf + 1, &buf); 80 ASSERT(*buf == ':'); 81 zb->zb_blkid = strtonum(buf + 1, &buf); 82 ASSERT(*buf == '\0'); 83 } 84 #endif 85 86 /* 87 * Log an uncorrectable error to the persistent error log. We add it to the 88 * spa's list of pending errors. The changes are actually synced out to disk 89 * during spa_errlog_sync(). 90 */ 91 void 92 spa_log_error(spa_t *spa, zio_t *zio) 93 { 94 zbookmark_t *zb = &zio->io_logical->io_bookmark; 95 spa_error_entry_t search; 96 spa_error_entry_t *new; 97 avl_tree_t *tree; 98 avl_index_t where; 99 100 /* 101 * If we are trying to import a pool, ignore any errors, as we won't be 102 * writing to the pool any time soon. 103 */ 104 if (spa_load_state(spa) == SPA_LOAD_TRYIMPORT) 105 return; 106 107 mutex_enter(&spa->spa_errlist_lock); 108 109 /* 110 * If we have had a request to rotate the log, log it to the next list 111 * instead of the current one. 112 */ 113 if (spa->spa_scrub_active || spa->spa_scrub_finished) 114 tree = &spa->spa_errlist_scrub; 115 else 116 tree = &spa->spa_errlist_last; 117 118 search.se_bookmark = *zb; 119 if (avl_find(tree, &search, &where) != NULL) { 120 mutex_exit(&spa->spa_errlist_lock); 121 return; 122 } 123 124 new = kmem_zalloc(sizeof (spa_error_entry_t), KM_SLEEP); 125 new->se_bookmark = *zb; 126 avl_insert(tree, new, where); 127 128 mutex_exit(&spa->spa_errlist_lock); 129 } 130 131 /* 132 * Return the number of errors currently in the error log. This is actually the 133 * sum of both the last log and the current log, since we don't know the union 134 * of these logs until we reach userland. 135 */ 136 uint64_t 137 spa_get_errlog_size(spa_t *spa) 138 { 139 uint64_t total = 0, count; 140 141 mutex_enter(&spa->spa_errlog_lock); 142 if (spa->spa_errlog_scrub != 0 && 143 zap_count(spa->spa_meta_objset, spa->spa_errlog_scrub, 144 &count) == 0) 145 total += count; 146 147 if (spa->spa_errlog_last != 0 && !spa->spa_scrub_finished && 148 zap_count(spa->spa_meta_objset, spa->spa_errlog_last, 149 &count) == 0) 150 total += count; 151 mutex_exit(&spa->spa_errlog_lock); 152 153 mutex_enter(&spa->spa_errlist_lock); 154 total += avl_numnodes(&spa->spa_errlist_last); 155 total += avl_numnodes(&spa->spa_errlist_scrub); 156 mutex_exit(&spa->spa_errlist_lock); 157 158 return (total); 159 } 160 161 #ifdef _KERNEL 162 static int 163 process_error_log(spa_t *spa, uint64_t obj, void *addr, size_t *count) 164 { 165 zap_cursor_t zc; 166 zap_attribute_t za; 167 zbookmark_t zb; 168 169 if (obj == 0) 170 return (0); 171 172 for (zap_cursor_init(&zc, spa->spa_meta_objset, obj); 173 zap_cursor_retrieve(&zc, &za) == 0; 174 zap_cursor_advance(&zc)) { 175 176 if (*count == 0) { 177 zap_cursor_fini(&zc); 178 return (ENOMEM); 179 } 180 181 name_to_bookmark(za.za_name, &zb); 182 183 if (copyout(&zb, (char *)addr + 184 (*count - 1) * sizeof (zbookmark_t), 185 sizeof (zbookmark_t)) != 0) 186 return (EFAULT); 187 188 *count -= 1; 189 } 190 191 zap_cursor_fini(&zc); 192 193 return (0); 194 } 195 196 static int 197 process_error_list(avl_tree_t *list, void *addr, size_t *count) 198 { 199 spa_error_entry_t *se; 200 201 for (se = avl_first(list); se != NULL; se = AVL_NEXT(list, se)) { 202 203 if (*count == 0) 204 return (ENOMEM); 205 206 if (copyout(&se->se_bookmark, (char *)addr + 207 (*count - 1) * sizeof (zbookmark_t), 208 sizeof (zbookmark_t)) != 0) 209 return (EFAULT); 210 211 *count -= 1; 212 } 213 214 return (0); 215 } 216 #endif 217 218 /* 219 * Copy all known errors to userland as an array of bookmarks. This is 220 * actually a union of the on-disk last log and current log, as well as any 221 * pending error requests. 222 * 223 * Because the act of reading the on-disk log could cause errors to be 224 * generated, we have two separate locks: one for the error log and one for the 225 * in-core error lists. We only need the error list lock to log and error, so 226 * we grab the error log lock while we read the on-disk logs, and only pick up 227 * the error list lock when we are finished. 228 */ 229 int 230 spa_get_errlog(spa_t *spa, void *uaddr, size_t *count) 231 { 232 int ret = 0; 233 234 #ifdef _KERNEL 235 mutex_enter(&spa->spa_errlog_lock); 236 237 ret = process_error_log(spa, spa->spa_errlog_scrub, uaddr, count); 238 239 if (!ret && !spa->spa_scrub_finished) 240 ret = process_error_log(spa, spa->spa_errlog_last, uaddr, 241 count); 242 243 mutex_enter(&spa->spa_errlist_lock); 244 if (!ret) 245 ret = process_error_list(&spa->spa_errlist_scrub, uaddr, 246 count); 247 if (!ret) 248 ret = process_error_list(&spa->spa_errlist_last, uaddr, 249 count); 250 mutex_exit(&spa->spa_errlist_lock); 251 252 mutex_exit(&spa->spa_errlog_lock); 253 #endif 254 255 return (ret); 256 } 257 258 /* 259 * Called when a scrub completes. This simply set a bit which tells which AVL 260 * tree to add new errors. spa_errlog_sync() is responsible for actually 261 * syncing the changes to the underlying objects. 262 */ 263 void 264 spa_errlog_rotate(spa_t *spa) 265 { 266 mutex_enter(&spa->spa_errlist_lock); 267 spa->spa_scrub_finished = B_TRUE; 268 mutex_exit(&spa->spa_errlist_lock); 269 } 270 271 /* 272 * Discard any pending errors from the spa_t. Called when unloading a faulted 273 * pool, as the errors encountered during the open cannot be synced to disk. 274 */ 275 void 276 spa_errlog_drain(spa_t *spa) 277 { 278 spa_error_entry_t *se; 279 void *cookie; 280 281 mutex_enter(&spa->spa_errlist_lock); 282 283 cookie = NULL; 284 while ((se = avl_destroy_nodes(&spa->spa_errlist_last, 285 &cookie)) != NULL) 286 kmem_free(se, sizeof (spa_error_entry_t)); 287 cookie = NULL; 288 while ((se = avl_destroy_nodes(&spa->spa_errlist_scrub, 289 &cookie)) != NULL) 290 kmem_free(se, sizeof (spa_error_entry_t)); 291 292 mutex_exit(&spa->spa_errlist_lock); 293 } 294 295 /* 296 * Process a list of errors into the current on-disk log. 297 */ 298 static void 299 sync_error_list(spa_t *spa, avl_tree_t *t, uint64_t *obj, dmu_tx_t *tx) 300 { 301 spa_error_entry_t *se; 302 char buf[64]; 303 void *cookie; 304 305 if (avl_numnodes(t) != 0) { 306 /* create log if necessary */ 307 if (*obj == 0) 308 *obj = zap_create(spa->spa_meta_objset, 309 DMU_OT_ERROR_LOG, DMU_OT_NONE, 310 0, tx); 311 312 /* add errors to the current log */ 313 for (se = avl_first(t); se != NULL; se = AVL_NEXT(t, se)) { 314 char *name = se->se_name ? se->se_name : ""; 315 316 bookmark_to_name(&se->se_bookmark, buf, sizeof (buf)); 317 318 (void) zap_update(spa->spa_meta_objset, 319 *obj, buf, 1, strlen(name) + 1, name, tx); 320 } 321 322 /* purge the error list */ 323 cookie = NULL; 324 while ((se = avl_destroy_nodes(t, &cookie)) != NULL) 325 kmem_free(se, sizeof (spa_error_entry_t)); 326 } 327 } 328 329 /* 330 * Sync the error log out to disk. This is a little tricky because the act of 331 * writing the error log requires the spa_errlist_lock. So, we need to lock the 332 * error lists, take a copy of the lists, and then reinitialize them. Then, we 333 * drop the error list lock and take the error log lock, at which point we 334 * do the errlog processing. Then, if we encounter an I/O error during this 335 * process, we can successfully add the error to the list. Note that this will 336 * result in the perpetual recycling of errors, but it is an unlikely situation 337 * and not a performance critical operation. 338 */ 339 void 340 spa_errlog_sync(spa_t *spa, uint64_t txg) 341 { 342 dmu_tx_t *tx; 343 avl_tree_t scrub, last; 344 int scrub_finished; 345 346 mutex_enter(&spa->spa_errlist_lock); 347 348 /* 349 * Bail out early under normal circumstances. 350 */ 351 if (avl_numnodes(&spa->spa_errlist_scrub) == 0 && 352 avl_numnodes(&spa->spa_errlist_last) == 0 && 353 !spa->spa_scrub_finished) { 354 mutex_exit(&spa->spa_errlist_lock); 355 return; 356 } 357 358 spa_get_errlists(spa, &last, &scrub); 359 scrub_finished = spa->spa_scrub_finished; 360 spa->spa_scrub_finished = B_FALSE; 361 362 mutex_exit(&spa->spa_errlist_lock); 363 mutex_enter(&spa->spa_errlog_lock); 364 365 tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg); 366 367 /* 368 * Sync out the current list of errors. 369 */ 370 sync_error_list(spa, &last, &spa->spa_errlog_last, tx); 371 372 /* 373 * Rotate the log if necessary. 374 */ 375 if (scrub_finished) { 376 if (spa->spa_errlog_last != 0) 377 VERIFY(dmu_object_free(spa->spa_meta_objset, 378 spa->spa_errlog_last, tx) == 0); 379 spa->spa_errlog_last = spa->spa_errlog_scrub; 380 spa->spa_errlog_scrub = 0; 381 382 sync_error_list(spa, &scrub, &spa->spa_errlog_last, tx); 383 } 384 385 /* 386 * Sync out any pending scrub errors. 387 */ 388 sync_error_list(spa, &scrub, &spa->spa_errlog_scrub, tx); 389 390 /* 391 * Update the MOS to reflect the new values. 392 */ 393 (void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT, 394 DMU_POOL_ERRLOG_LAST, sizeof (uint64_t), 1, 395 &spa->spa_errlog_last, tx); 396 (void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT, 397 DMU_POOL_ERRLOG_SCRUB, sizeof (uint64_t), 1, 398 &spa->spa_errlog_scrub, tx); 399 400 dmu_tx_commit(tx); 401 402 mutex_exit(&spa->spa_errlog_lock); 403 } 404