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-rw-r--r--uts/common/fs/zfs/spa_errlog.c403
1 files changed, 403 insertions, 0 deletions
diff --git a/uts/common/fs/zfs/spa_errlog.c b/uts/common/fs/zfs/spa_errlog.c
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+++ b/uts/common/fs/zfs/spa_errlog.c
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+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved.
+ */
+
+/*
+ * Routines to manage the on-disk persistent error log.
+ *
+ * Each pool stores a log of all logical data errors seen during normal
+ * operation. This is actually the union of two distinct logs: the last log,
+ * and the current log. All errors seen are logged to the current log. When a
+ * scrub completes, the current log becomes the last log, the last log is thrown
+ * out, and the current log is reinitialized. This way, if an error is somehow
+ * corrected, a new scrub will show that that it no longer exists, and will be
+ * deleted from the log when the scrub completes.
+ *
+ * The log is stored using a ZAP object whose key is a string form of the
+ * zbookmark tuple (objset, object, level, blkid), and whose contents is an
+ * optional 'objset:object' human-readable string describing the data. When an
+ * error is first logged, this string will be empty, indicating that no name is
+ * known. This prevents us from having to issue a potentially large amount of
+ * I/O to discover the object name during an error path. Instead, we do the
+ * calculation when the data is requested, storing the result so future queries
+ * will be faster.
+ *
+ * This log is then shipped into an nvlist where the key is the dataset name and
+ * the value is the object name. Userland is then responsible for uniquifying
+ * this list and displaying it to the user.
+ */
+
+#include <sys/dmu_tx.h>
+#include <sys/spa.h>
+#include <sys/spa_impl.h>
+#include <sys/zap.h>
+#include <sys/zio.h>
+
+
+/*
+ * Convert a bookmark to a string.
+ */
+static void
+bookmark_to_name(zbookmark_t *zb, char *buf, size_t len)
+{
+ (void) snprintf(buf, len, "%llx:%llx:%llx:%llx",
+ (u_longlong_t)zb->zb_objset, (u_longlong_t)zb->zb_object,
+ (u_longlong_t)zb->zb_level, (u_longlong_t)zb->zb_blkid);
+}
+
+/*
+ * Convert a string to a bookmark
+ */
+#ifdef _KERNEL
+static void
+name_to_bookmark(char *buf, zbookmark_t *zb)
+{
+ zb->zb_objset = strtonum(buf, &buf);
+ ASSERT(*buf == ':');
+ zb->zb_object = strtonum(buf + 1, &buf);
+ ASSERT(*buf == ':');
+ zb->zb_level = (int)strtonum(buf + 1, &buf);
+ ASSERT(*buf == ':');
+ zb->zb_blkid = strtonum(buf + 1, &buf);
+ ASSERT(*buf == '\0');
+}
+#endif
+
+/*
+ * Log an uncorrectable error to the persistent error log. We add it to the
+ * spa's list of pending errors. The changes are actually synced out to disk
+ * during spa_errlog_sync().
+ */
+void
+spa_log_error(spa_t *spa, zio_t *zio)
+{
+ zbookmark_t *zb = &zio->io_logical->io_bookmark;
+ spa_error_entry_t search;
+ spa_error_entry_t *new;
+ avl_tree_t *tree;
+ avl_index_t where;
+
+ /*
+ * If we are trying to import a pool, ignore any errors, as we won't be
+ * writing to the pool any time soon.
+ */
+ if (spa_load_state(spa) == SPA_LOAD_TRYIMPORT)
+ return;
+
+ mutex_enter(&spa->spa_errlist_lock);
+
+ /*
+ * If we have had a request to rotate the log, log it to the next list
+ * instead of the current one.
+ */
+ if (spa->spa_scrub_active || spa->spa_scrub_finished)
+ tree = &spa->spa_errlist_scrub;
+ else
+ tree = &spa->spa_errlist_last;
+
+ search.se_bookmark = *zb;
+ if (avl_find(tree, &search, &where) != NULL) {
+ mutex_exit(&spa->spa_errlist_lock);
+ return;
+ }
+
+ new = kmem_zalloc(sizeof (spa_error_entry_t), KM_SLEEP);
+ new->se_bookmark = *zb;
+ avl_insert(tree, new, where);
+
+ mutex_exit(&spa->spa_errlist_lock);
+}
+
+/*
+ * Return the number of errors currently in the error log. This is actually the
+ * sum of both the last log and the current log, since we don't know the union
+ * of these logs until we reach userland.
+ */
+uint64_t
+spa_get_errlog_size(spa_t *spa)
+{
+ uint64_t total = 0, count;
+
+ mutex_enter(&spa->spa_errlog_lock);
+ if (spa->spa_errlog_scrub != 0 &&
+ zap_count(spa->spa_meta_objset, spa->spa_errlog_scrub,
+ &count) == 0)
+ total += count;
+
+ if (spa->spa_errlog_last != 0 && !spa->spa_scrub_finished &&
+ zap_count(spa->spa_meta_objset, spa->spa_errlog_last,
+ &count) == 0)
+ total += count;
+ mutex_exit(&spa->spa_errlog_lock);
+
+ mutex_enter(&spa->spa_errlist_lock);
+ total += avl_numnodes(&spa->spa_errlist_last);
+ total += avl_numnodes(&spa->spa_errlist_scrub);
+ mutex_exit(&spa->spa_errlist_lock);
+
+ return (total);
+}
+
+#ifdef _KERNEL
+static int
+process_error_log(spa_t *spa, uint64_t obj, void *addr, size_t *count)
+{
+ zap_cursor_t zc;
+ zap_attribute_t za;
+ zbookmark_t zb;
+
+ if (obj == 0)
+ return (0);
+
+ for (zap_cursor_init(&zc, spa->spa_meta_objset, obj);
+ zap_cursor_retrieve(&zc, &za) == 0;
+ zap_cursor_advance(&zc)) {
+
+ if (*count == 0) {
+ zap_cursor_fini(&zc);
+ return (ENOMEM);
+ }
+
+ name_to_bookmark(za.za_name, &zb);
+
+ if (copyout(&zb, (char *)addr +
+ (*count - 1) * sizeof (zbookmark_t),
+ sizeof (zbookmark_t)) != 0)
+ return (EFAULT);
+
+ *count -= 1;
+ }
+
+ zap_cursor_fini(&zc);
+
+ return (0);
+}
+
+static int
+process_error_list(avl_tree_t *list, void *addr, size_t *count)
+{
+ spa_error_entry_t *se;
+
+ for (se = avl_first(list); se != NULL; se = AVL_NEXT(list, se)) {
+
+ if (*count == 0)
+ return (ENOMEM);
+
+ if (copyout(&se->se_bookmark, (char *)addr +
+ (*count - 1) * sizeof (zbookmark_t),
+ sizeof (zbookmark_t)) != 0)
+ return (EFAULT);
+
+ *count -= 1;
+ }
+
+ return (0);
+}
+#endif
+
+/*
+ * Copy all known errors to userland as an array of bookmarks. This is
+ * actually a union of the on-disk last log and current log, as well as any
+ * pending error requests.
+ *
+ * Because the act of reading the on-disk log could cause errors to be
+ * generated, we have two separate locks: one for the error log and one for the
+ * in-core error lists. We only need the error list lock to log and error, so
+ * we grab the error log lock while we read the on-disk logs, and only pick up
+ * the error list lock when we are finished.
+ */
+int
+spa_get_errlog(spa_t *spa, void *uaddr, size_t *count)
+{
+ int ret = 0;
+
+#ifdef _KERNEL
+ mutex_enter(&spa->spa_errlog_lock);
+
+ ret = process_error_log(spa, spa->spa_errlog_scrub, uaddr, count);
+
+ if (!ret && !spa->spa_scrub_finished)
+ ret = process_error_log(spa, spa->spa_errlog_last, uaddr,
+ count);
+
+ mutex_enter(&spa->spa_errlist_lock);
+ if (!ret)
+ ret = process_error_list(&spa->spa_errlist_scrub, uaddr,
+ count);
+ if (!ret)
+ ret = process_error_list(&spa->spa_errlist_last, uaddr,
+ count);
+ mutex_exit(&spa->spa_errlist_lock);
+
+ mutex_exit(&spa->spa_errlog_lock);
+#endif
+
+ return (ret);
+}
+
+/*
+ * Called when a scrub completes. This simply set a bit which tells which AVL
+ * tree to add new errors. spa_errlog_sync() is responsible for actually
+ * syncing the changes to the underlying objects.
+ */
+void
+spa_errlog_rotate(spa_t *spa)
+{
+ mutex_enter(&spa->spa_errlist_lock);
+ spa->spa_scrub_finished = B_TRUE;
+ mutex_exit(&spa->spa_errlist_lock);
+}
+
+/*
+ * Discard any pending errors from the spa_t. Called when unloading a faulted
+ * pool, as the errors encountered during the open cannot be synced to disk.
+ */
+void
+spa_errlog_drain(spa_t *spa)
+{
+ spa_error_entry_t *se;
+ void *cookie;
+
+ mutex_enter(&spa->spa_errlist_lock);
+
+ cookie = NULL;
+ while ((se = avl_destroy_nodes(&spa->spa_errlist_last,
+ &cookie)) != NULL)
+ kmem_free(se, sizeof (spa_error_entry_t));
+ cookie = NULL;
+ while ((se = avl_destroy_nodes(&spa->spa_errlist_scrub,
+ &cookie)) != NULL)
+ kmem_free(se, sizeof (spa_error_entry_t));
+
+ mutex_exit(&spa->spa_errlist_lock);
+}
+
+/*
+ * Process a list of errors into the current on-disk log.
+ */
+static void
+sync_error_list(spa_t *spa, avl_tree_t *t, uint64_t *obj, dmu_tx_t *tx)
+{
+ spa_error_entry_t *se;
+ char buf[64];
+ void *cookie;
+
+ if (avl_numnodes(t) != 0) {
+ /* create log if necessary */
+ if (*obj == 0)
+ *obj = zap_create(spa->spa_meta_objset,
+ DMU_OT_ERROR_LOG, DMU_OT_NONE,
+ 0, tx);
+
+ /* add errors to the current log */
+ for (se = avl_first(t); se != NULL; se = AVL_NEXT(t, se)) {
+ char *name = se->se_name ? se->se_name : "";
+
+ bookmark_to_name(&se->se_bookmark, buf, sizeof (buf));
+
+ (void) zap_update(spa->spa_meta_objset,
+ *obj, buf, 1, strlen(name) + 1, name, tx);
+ }
+
+ /* purge the error list */
+ cookie = NULL;
+ while ((se = avl_destroy_nodes(t, &cookie)) != NULL)
+ kmem_free(se, sizeof (spa_error_entry_t));
+ }
+}
+
+/*
+ * Sync the error log out to disk. This is a little tricky because the act of
+ * writing the error log requires the spa_errlist_lock. So, we need to lock the
+ * error lists, take a copy of the lists, and then reinitialize them. Then, we
+ * drop the error list lock and take the error log lock, at which point we
+ * do the errlog processing. Then, if we encounter an I/O error during this
+ * process, we can successfully add the error to the list. Note that this will
+ * result in the perpetual recycling of errors, but it is an unlikely situation
+ * and not a performance critical operation.
+ */
+void
+spa_errlog_sync(spa_t *spa, uint64_t txg)
+{
+ dmu_tx_t *tx;
+ avl_tree_t scrub, last;
+ int scrub_finished;
+
+ mutex_enter(&spa->spa_errlist_lock);
+
+ /*
+ * Bail out early under normal circumstances.
+ */
+ if (avl_numnodes(&spa->spa_errlist_scrub) == 0 &&
+ avl_numnodes(&spa->spa_errlist_last) == 0 &&
+ !spa->spa_scrub_finished) {
+ mutex_exit(&spa->spa_errlist_lock);
+ return;
+ }
+
+ spa_get_errlists(spa, &last, &scrub);
+ scrub_finished = spa->spa_scrub_finished;
+ spa->spa_scrub_finished = B_FALSE;
+
+ mutex_exit(&spa->spa_errlist_lock);
+ mutex_enter(&spa->spa_errlog_lock);
+
+ tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
+
+ /*
+ * Sync out the current list of errors.
+ */
+ sync_error_list(spa, &last, &spa->spa_errlog_last, tx);
+
+ /*
+ * Rotate the log if necessary.
+ */
+ if (scrub_finished) {
+ if (spa->spa_errlog_last != 0)
+ VERIFY(dmu_object_free(spa->spa_meta_objset,
+ spa->spa_errlog_last, tx) == 0);
+ spa->spa_errlog_last = spa->spa_errlog_scrub;
+ spa->spa_errlog_scrub = 0;
+
+ sync_error_list(spa, &scrub, &spa->spa_errlog_last, tx);
+ }
+
+ /*
+ * Sync out any pending scrub errors.
+ */
+ sync_error_list(spa, &scrub, &spa->spa_errlog_scrub, tx);
+
+ /*
+ * Update the MOS to reflect the new values.
+ */
+ (void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+ DMU_POOL_ERRLOG_LAST, sizeof (uint64_t), 1,
+ &spa->spa_errlog_last, tx);
+ (void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+ DMU_POOL_ERRLOG_SCRUB, sizeof (uint64_t), 1,
+ &spa->spa_errlog_scrub, tx);
+
+ dmu_tx_commit(tx);
+
+ mutex_exit(&spa->spa_errlog_lock);
+}