usr/src/uts/common/fs/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  */
  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 }