module/zfs/spa_errlog.c

   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  * Copyright (c) 2013, 2014 by Delphix. All rights reserved.
  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 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_phys 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 /*
  59  * Convert a bookmark to a string.
  60  */
  61 static void
  62 bookmark_to_name(zbookmark_phys_t *zb, char *buf, size_t len)
  63 {
  64         (void) snprintf(buf, len, "%llx:%llx:%llx:%llx",
  65             (u_longlong_t)zb->zb_objset, (u_longlong_t)zb->zb_object,
  66             (u_longlong_t)zb->zb_level, (u_longlong_t)zb->zb_blkid);
  67 }
  68
  69 /*
  70  * Convert a string to a bookmark
  71  */
  72 #ifdef _KERNEL
  73 static void
  74 name_to_bookmark(char *buf, zbookmark_phys_t *zb)
  75 {
  76         zb->zb_objset = zfs_strtonum(buf, &buf);
  77         ASSERT(*buf == ':');
  78         zb->zb_object = zfs_strtonum(buf + 1, &buf);
  79         ASSERT(*buf == ':');
  80         zb->zb_level = (int)zfs_strtonum(buf + 1, &buf);
  81         ASSERT(*buf == ':');
  82         zb->zb_blkid = zfs_strtonum(buf + 1, &buf);
  83         ASSERT(*buf == '\0');
  84 }
  85 #endif
  86
  87 /*
  88  * Log an uncorrectable error to the persistent error log.  We add it to the
  89  * spa's list of pending errors.  The changes are actually synced out to disk
  90  * during spa_errlog_sync().
  91  */
  92 void
  93 spa_log_error(spa_t *spa, const zbookmark_phys_t *zb)
  94 {
  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_phys_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 (SET_ERROR(ENOMEM));
 179                 }
 180
 181                 name_to_bookmark(za.za_name, &zb);
 182
 183                 if (copyout(&zb, (char *)addr +
 184                     (*count - 1) * sizeof (zbookmark_phys_t),
 185                     sizeof (zbookmark_phys_t)) != 0) {
 186                         zap_cursor_fini(&zc);
 187                         return (SET_ERROR(EFAULT));
 188                 }
 189
 190                 *count -= 1;
 191         }
 192
 193         zap_cursor_fini(&zc);
 194
 195         return (0);
 196 }
 197
 198 static int
 199 process_error_list(avl_tree_t *list, void *addr, size_t *count)
 200 {
 201         spa_error_entry_t *se;
 202
 203         for (se = avl_first(list); se != NULL; se = AVL_NEXT(list, se)) {
 204
 205                 if (*count == 0)
 206                         return (SET_ERROR(ENOMEM));
 207
 208                 if (copyout(&se->se_bookmark, (char *)addr +
 209                     (*count - 1) * sizeof (zbookmark_phys_t),
 210                     sizeof (zbookmark_phys_t)) != 0)
 211                         return (SET_ERROR(EFAULT));
 212
 213                 *count -= 1;
 214         }
 215
 216         return (0);
 217 }
 218 #endif
 219
 220 /*
 221  * Copy all known errors to userland as an array of bookmarks.  This is
 222  * actually a union of the on-disk last log and current log, as well as any
 223  * pending error requests.
 224  *
 225  * Because the act of reading the on-disk log could cause errors to be
 226  * generated, we have two separate locks: one for the error log and one for the
 227  * in-core error lists.  We only need the error list lock to log and error, so
 228  * we grab the error log lock while we read the on-disk logs, and only pick up
 229  * the error list lock when we are finished.
 230  */
 231 int
 232 spa_get_errlog(spa_t *spa, void *uaddr, size_t *count)
 233 {
 234         int ret = 0;
 235
 236 #ifdef _KERNEL
 237         mutex_enter(&spa->spa_errlog_lock);
 238
 239         ret = process_error_log(spa, spa->spa_errlog_scrub, uaddr, count);
 240
 241         if (!ret && !spa->spa_scrub_finished)
 242                 ret = process_error_log(spa, spa->spa_errlog_last, uaddr,
 243                     count);
 244
 245         mutex_enter(&spa->spa_errlist_lock);
 246         if (!ret)
 247                 ret = process_error_list(&spa->spa_errlist_scrub, uaddr,
 248                     count);
 249         if (!ret)
 250                 ret = process_error_list(&spa->spa_errlist_last, uaddr,
 251                     count);
 252         mutex_exit(&spa->spa_errlist_lock);
 253
 254         mutex_exit(&spa->spa_errlog_lock);
 255 #else
 256         (void) spa, (void) uaddr, (void) count;
 257 #endif
 258
 259         return (ret);
 260 }
 261
 262 /*
 263  * Called when a scrub completes.  This simply set a bit which tells which AVL
 264  * tree to add new errors.  spa_errlog_sync() is responsible for actually
 265  * syncing the changes to the underlying objects.
 266  */
 267 void
 268 spa_errlog_rotate(spa_t *spa)
 269 {
 270         mutex_enter(&spa->spa_errlist_lock);
 271         spa->spa_scrub_finished = B_TRUE;
 272         mutex_exit(&spa->spa_errlist_lock);
 273 }
 274
 275 /*
 276  * Discard any pending errors from the spa_t.  Called when unloading a faulted
 277  * pool, as the errors encountered during the open cannot be synced to disk.
 278  */
 279 void
 280 spa_errlog_drain(spa_t *spa)
 281 {
 282         spa_error_entry_t *se;
 283         void *cookie;
 284
 285         mutex_enter(&spa->spa_errlist_lock);
 286
 287         cookie = NULL;
 288         while ((se = avl_destroy_nodes(&spa->spa_errlist_last,
 289             &cookie)) != NULL)
 290                 kmem_free(se, sizeof (spa_error_entry_t));
 291         cookie = NULL;
 292         while ((se = avl_destroy_nodes(&spa->spa_errlist_scrub,
 293             &cookie)) != NULL)
 294                 kmem_free(se, sizeof (spa_error_entry_t));
 295
 296         mutex_exit(&spa->spa_errlist_lock);
 297 }
 298
 299 /*
 300  * Process a list of errors into the current on-disk log.
 301  */
 302 static void
 303 sync_error_list(spa_t *spa, avl_tree_t *t, uint64_t *obj, dmu_tx_t *tx)
 304 {
 305         spa_error_entry_t *se;
 306         char buf[64];
 307         void *cookie;
 308
 309         if (avl_numnodes(t) != 0) {
 310                 /* create log if necessary */
 311                 if (*obj == 0)
 312                         *obj = zap_create(spa->spa_meta_objset,
 313                             DMU_OT_ERROR_LOG, DMU_OT_NONE,
 314                             0, tx);
 315
 316                 /* add errors to the current log */
 317                 for (se = avl_first(t); se != NULL; se = AVL_NEXT(t, se)) {
 318                         char *name = se->se_name ? se->se_name : "";
 319
 320                         bookmark_to_name(&se->se_bookmark, buf, sizeof (buf));
 321
 322                         (void) zap_update(spa->spa_meta_objset,
 323                             *obj, buf, 1, strlen(name) + 1, name, tx);
 324                 }
 325
 326                 /* purge the error list */
 327                 cookie = NULL;
 328                 while ((se = avl_destroy_nodes(t, &cookie)) != NULL)
 329                         kmem_free(se, sizeof (spa_error_entry_t));
 330         }
 331 }
 332
 333 /*
 334  * Sync the error log out to disk.  This is a little tricky because the act of
 335  * writing the error log requires the spa_errlist_lock.  So, we need to lock the
 336  * error lists, take a copy of the lists, and then reinitialize them.  Then, we
 337  * drop the error list lock and take the error log lock, at which point we
 338  * do the errlog processing.  Then, if we encounter an I/O error during this
 339  * process, we can successfully add the error to the list.  Note that this will
 340  * result in the perpetual recycling of errors, but it is an unlikely situation
 341  * and not a performance critical operation.
 342  */
 343 void
 344 spa_errlog_sync(spa_t *spa, uint64_t txg)
 345 {
 346         dmu_tx_t *tx;
 347         avl_tree_t scrub, last;
 348         int scrub_finished;
 349
 350         mutex_enter(&spa->spa_errlist_lock);
 351
 352         /*
 353          * Bail out early under normal circumstances.
 354          */
 355         if (avl_numnodes(&spa->spa_errlist_scrub) == 0 &&
 356             avl_numnodes(&spa->spa_errlist_last) == 0 &&
 357             !spa->spa_scrub_finished) {
 358                 mutex_exit(&spa->spa_errlist_lock);
 359                 return;
 360         }
 361
 362         spa_get_errlists(spa, &last, &scrub);
 363         scrub_finished = spa->spa_scrub_finished;
 364         spa->spa_scrub_finished = B_FALSE;
 365
 366         mutex_exit(&spa->spa_errlist_lock);
 367         mutex_enter(&spa->spa_errlog_lock);
 368
 369         tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
 370
 371         /*
 372          * Sync out the current list of errors.
 373          */
 374         sync_error_list(spa, &last, &spa->spa_errlog_last, tx);
 375
 376         /*
 377          * Rotate the log if necessary.
 378          */
 379         if (scrub_finished) {
 380                 if (spa->spa_errlog_last != 0)
 381                         VERIFY(dmu_object_free(spa->spa_meta_objset,
 382                             spa->spa_errlog_last, tx) == 0);
 383                 spa->spa_errlog_last = spa->spa_errlog_scrub;
 384                 spa->spa_errlog_scrub = 0;
 385
 386                 sync_error_list(spa, &scrub, &spa->spa_errlog_last, tx);
 387         }
 388
 389         /*
 390          * Sync out any pending scrub errors.
 391          */
 392         sync_error_list(spa, &scrub, &spa->spa_errlog_scrub, tx);
 393
 394         /*
 395          * Update the MOS to reflect the new values.
 396          */
 397         (void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 398             DMU_POOL_ERRLOG_LAST, sizeof (uint64_t), 1,
 399             &spa->spa_errlog_last, tx);
 400         (void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 401             DMU_POOL_ERRLOG_SCRUB, sizeof (uint64_t), 1,
 402             &spa->spa_errlog_scrub, tx);
 403
 404         dmu_tx_commit(tx);
 405
 406         mutex_exit(&spa->spa_errlog_lock);
 407 }
 408
 409 #if defined(_KERNEL)
 410 /* error handling */
 411 EXPORT_SYMBOL(spa_log_error);
 412 EXPORT_SYMBOL(spa_get_errlog_size);
 413 EXPORT_SYMBOL(spa_get_errlog);
 414 EXPORT_SYMBOL(spa_errlog_rotate);
 415 EXPORT_SYMBOL(spa_errlog_drain);
 416 EXPORT_SYMBOL(spa_errlog_sync);
 417 EXPORT_SYMBOL(spa_get_errlists);
 418 #endif