zfs/lib/libzpool/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 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 }