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 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 }