kernel/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  * 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 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, zio_t *zio)
  94 {
  95         zbookmark_phys_t *zb = &zio->io_logical->io_bookmark;
  96         spa_error_entry_t search;
  97         spa_error_entry_t *new;
  98         avl_tree_t *tree;
  99         avl_index_t where;
 100
 101         /*
 102          * If we are trying to import a pool, ignore any errors, as we won't be
 103          * writing to the pool any time soon.
 104          */
 105         if (spa_load_state(spa) == SPA_LOAD_TRYIMPORT)
 106                 return;
 107
 108         mutex_enter(&spa->spa_errlist_lock);
 109
 110         /*
 111          * If we have had a request to rotate the log, log it to the next list
 112          * instead of the current one.
 113          */
 114         if (spa->spa_scrub_active || spa->spa_scrub_finished)
 115                 tree = &spa->spa_errlist_scrub;
 116         else
 117                 tree = &spa->spa_errlist_last;
 118
 119         search.se_bookmark = *zb;
 120         if (avl_find(tree, &search, &where) != NULL) {
 121                 mutex_exit(&spa->spa_errlist_lock);
 122                 return;
 123         }
 124
 125         new = kmem_zalloc(sizeof (spa_error_entry_t), KM_SLEEP);
 126         new->se_bookmark = *zb;
 127         avl_insert(tree, new, where);
 128
 129         mutex_exit(&spa->spa_errlist_lock);
 130 }
 131
 132 /*
 133  * Return the number of errors currently in the error log.  This is actually the
 134  * sum of both the last log and the current log, since we don't know the union
 135  * of these logs until we reach userland.
 136  */
 137 uint64_t
 138 spa_get_errlog_size(spa_t *spa)
 139 {
 140         uint64_t total = 0, count;
 141
 142         mutex_enter(&spa->spa_errlog_lock);
 143         if (spa->spa_errlog_scrub != 0 &&
 144             zap_count(spa->spa_meta_objset, spa->spa_errlog_scrub,
 145             &count) == 0)
 146                 total += count;
 147
 148         if (spa->spa_errlog_last != 0 && !spa->spa_scrub_finished &&
 149             zap_count(spa->spa_meta_objset, spa->spa_errlog_last,
 150             &count) == 0)
 151                 total += count;
 152         mutex_exit(&spa->spa_errlog_lock);
 153
 154         mutex_enter(&spa->spa_errlist_lock);
 155         total += avl_numnodes(&spa->spa_errlist_last);
 156         total += avl_numnodes(&spa->spa_errlist_scrub);
 157         mutex_exit(&spa->spa_errlist_lock);
 158
 159         return (total);
 160 }
 161
 162 #ifdef _KERNEL
 163 static int
 164 process_error_log(spa_t *spa, uint64_t obj, void *addr, size_t *count)
 165 {
 166         zap_cursor_t zc;
 167         zap_attribute_t za;
 168         zbookmark_phys_t zb;
 169
 170         if (obj == 0)
 171                 return (0);
 172
 173         for (zap_cursor_init(&zc, spa->spa_meta_objset, obj);
 174             zap_cursor_retrieve(&zc, &za) == 0;
 175             zap_cursor_advance(&zc)) {
 176
 177                 if (*count == 0) {
 178                         zap_cursor_fini(&zc);
 179                         return (SET_ERROR(ENOMEM));
 180                 }
 181
 182                 name_to_bookmark(za.za_name, &zb);
 183
 184                 if (copyout(&zb, (char *)addr +
 185                     (*count - 1) * sizeof (zbookmark_phys_t),
 186                     sizeof (zbookmark_phys_t)) != 0) {
 187                         zap_cursor_fini(&zc);
 188                         return (SET_ERROR(EFAULT));
 189                 }
 190
 191                 *count -= 1;
 192         }
 193
 194         zap_cursor_fini(&zc);
 195
 196         return (0);
 197 }
 198
 199 static int
 200 process_error_list(avl_tree_t *list, void *addr, size_t *count)
 201 {
 202         spa_error_entry_t *se;
 203
 204         for (se = avl_first(list); se != NULL; se = AVL_NEXT(list, se)) {
 205
 206                 if (*count == 0)
 207                         return (SET_ERROR(ENOMEM));
 208
 209                 if (copyout(&se->se_bookmark, (char *)addr +
 210                     (*count - 1) * sizeof (zbookmark_phys_t),
 211                     sizeof (zbookmark_phys_t)) != 0)
 212                         return (SET_ERROR(EFAULT));
 213
 214                 *count -= 1;
 215         }
 216
 217         return (0);
 218 }
 219 #endif
 220
 221 /*
 222  * Copy all known errors to userland as an array of bookmarks.  This is
 223  * actually a union of the on-disk last log and current log, as well as any
 224  * pending error requests.
 225  *
 226  * Because the act of reading the on-disk log could cause errors to be
 227  * generated, we have two separate locks: one for the error log and one for the
 228  * in-core error lists.  We only need the error list lock to log and error, so
 229  * we grab the error log lock while we read the on-disk logs, and only pick up
 230  * the error list lock when we are finished.
 231  */
 232 int
 233 spa_get_errlog(spa_t *spa, void *uaddr, size_t *count)
 234 {
 235         int ret = 0;
 236
 237 #ifdef _KERNEL
 238         mutex_enter(&spa->spa_errlog_lock);
 239
 240         ret = process_error_log(spa, spa->spa_errlog_scrub, uaddr, count);
 241
 242         if (!ret && !spa->spa_scrub_finished)
 243                 ret = process_error_log(spa, spa->spa_errlog_last, uaddr,
 244                     count);
 245
 246         mutex_enter(&spa->spa_errlist_lock);
 247         if (!ret)
 248                 ret = process_error_list(&spa->spa_errlist_scrub, uaddr,
 249                     count);
 250         if (!ret)
 251                 ret = process_error_list(&spa->spa_errlist_last, uaddr,
 252                     count);
 253         mutex_exit(&spa->spa_errlist_lock);
 254
 255         mutex_exit(&spa->spa_errlog_lock);
 256 #endif
 257
 258         return (ret);
 259 }
 260
 261 /*
 262  * Called when a scrub completes.  This simply set a bit which tells which AVL
 263  * tree to add new errors.  spa_errlog_sync() is responsible for actually
 264  * syncing the changes to the underlying objects.
 265  */
 266 void
 267 spa_errlog_rotate(spa_t *spa)
 268 {
 269         mutex_enter(&spa->spa_errlist_lock);
 270         spa->spa_scrub_finished = B_TRUE;
 271         mutex_exit(&spa->spa_errlist_lock);
 272 }
 273
 274 /*
 275  * Discard any pending errors from the spa_t.  Called when unloading a faulted
 276  * pool, as the errors encountered during the open cannot be synced to disk.
 277  */
 278 void
 279 spa_errlog_drain(spa_t *spa)
 280 {
 281         spa_error_entry_t *se;
 282         void *cookie;
 283
 284         mutex_enter(&spa->spa_errlist_lock);
 285
 286         cookie = NULL;
 287         while ((se = avl_destroy_nodes(&spa->spa_errlist_last,
 288             &cookie)) != NULL)
 289                 kmem_free(se, sizeof (spa_error_entry_t));
 290         cookie = NULL;
 291         while ((se = avl_destroy_nodes(&spa->spa_errlist_scrub,
 292             &cookie)) != NULL)
 293                 kmem_free(se, sizeof (spa_error_entry_t));
 294
 295         mutex_exit(&spa->spa_errlist_lock);
 296 }
 297
 298 /*
 299  * Process a list of errors into the current on-disk log.
 300  */
 301 static void
 302 sync_error_list(spa_t *spa, avl_tree_t *t, uint64_t *obj, dmu_tx_t *tx)
 303 {
 304         spa_error_entry_t *se;
 305         char buf[64];
 306         void *cookie;
 307
 308         if (avl_numnodes(t) != 0) {
 309                 /* create log if necessary */
 310                 if (*obj == 0)
 311                         *obj = zap_create(spa->spa_meta_objset,
 312                             DMU_OT_ERROR_LOG, DMU_OT_NONE,
 313                             0, tx);
 314
 315                 /* add errors to the current log */
 316                 for (se = avl_first(t); se != NULL; se = AVL_NEXT(t, se)) {
 317                         char *name = se->se_name ? se->se_name : "";
 318
 319                         bookmark_to_name(&se->se_bookmark, buf, sizeof (buf));
 320
 321                         (void) zap_update(spa->spa_meta_objset,
 322                             *obj, buf, 1, strlen(name) + 1, name, tx);
 323                 }
 324
 325                 /* purge the error list */
 326                 cookie = NULL;
 327                 while ((se = avl_destroy_nodes(t, &cookie)) != NULL)
 328                         kmem_free(se, sizeof (spa_error_entry_t));
 329         }
 330 }
 331
 332 /*
 333  * Sync the error log out to disk.  This is a little tricky because the act of
 334  * writing the error log requires the spa_errlist_lock.  So, we need to lock the
 335  * error lists, take a copy of the lists, and then reinitialize them.  Then, we
 336  * drop the error list lock and take the error log lock, at which point we
 337  * do the errlog processing.  Then, if we encounter an I/O error during this
 338  * process, we can successfully add the error to the list.  Note that this will
 339  * result in the perpetual recycling of errors, but it is an unlikely situation
 340  * and not a performance critical operation.
 341  */
 342 void
 343 spa_errlog_sync(spa_t *spa, uint64_t txg)
 344 {
 345         dmu_tx_t *tx;
 346         avl_tree_t scrub, last;
 347         int scrub_finished;
 348
 349         mutex_enter(&spa->spa_errlist_lock);
 350
 351         /*
 352          * Bail out early under normal circumstances.
 353          */
 354         if (avl_numnodes(&spa->spa_errlist_scrub) == 0 &&
 355             avl_numnodes(&spa->spa_errlist_last) == 0 &&
 356             !spa->spa_scrub_finished) {
 357                 mutex_exit(&spa->spa_errlist_lock);
 358                 return;
 359         }
 360
 361         spa_get_errlists(spa, &last, &scrub);
 362         scrub_finished = spa->spa_scrub_finished;
 363         spa->spa_scrub_finished = B_FALSE;
 364
 365         mutex_exit(&spa->spa_errlist_lock);
 366         mutex_enter(&spa->spa_errlog_lock);
 367
 368         tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
 369
 370         /*
 371          * Sync out the current list of errors.
 372          */
 373         sync_error_list(spa, &last, &spa->spa_errlog_last, tx);
 374
 375         /*
 376          * Rotate the log if necessary.
 377          */
 378         if (scrub_finished) {
 379                 if (spa->spa_errlog_last != 0)
 380                         VERIFY(dmu_object_free(spa->spa_meta_objset,
 381                             spa->spa_errlog_last, tx) == 0);
 382                 spa->spa_errlog_last = spa->spa_errlog_scrub;
 383                 spa->spa_errlog_scrub = 0;
 384
 385                 sync_error_list(spa, &scrub, &spa->spa_errlog_last, tx);
 386         }
 387
 388         /*
 389          * Sync out any pending scrub errors.
 390          */
 391         sync_error_list(spa, &scrub, &spa->spa_errlog_scrub, tx);
 392
 393         /*
 394          * Update the MOS to reflect the new values.
 395          */
 396         (void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 397             DMU_POOL_ERRLOG_LAST, sizeof (uint64_t), 1,
 398             &spa->spa_errlog_last, tx);
 399         (void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 400             DMU_POOL_ERRLOG_SCRUB, sizeof (uint64_t), 1,
 401             &spa->spa_errlog_scrub, tx);
 402
 403         dmu_tx_commit(tx);
 404
 405         mutex_exit(&spa->spa_errlog_lock);
 406 }