1 files changed, 440 insertions, 0 deletions
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa_errlog.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa_errlog.c
new file mode 100644
index 0000000..c52acaf
--- /dev/null
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa_errlog.c
@@ -0,0 +1,440 @@
+/*
+ * 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 2006 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#pragma ident	"%Z%%M%	%I%	%E% SMI"
+
+/*
+ * 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>
+
+/*
+ * This is a stripped-down version of strtoull, suitable only for converting
+ * lowercase hexidecimal numbers that don't overflow.
+ */
+#ifdef _KERNEL
+static uint64_t
+_strtonum(char *str, char **nptr)
+{
+	uint64_t val = 0;
+	char c;
+	int digit;
+
+	while ((c = *str) != '\0') {
+		if (c >= '0' && c <= '9')
+			digit = c - '0';
+		else if (c >= 'a' && c <= 'f')
+			digit = 10 + c - 'a';
+		else
+			break;
+
+		val *= 16;
+		val += digit;
+
+		str++;
+	}
+
+	*nptr = str;
+
+	return (val);
+}
+#endif
+
+/*
+ * 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->spa_load_state == 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);
+
+	ASSERT(!spa->spa_scrub_finished);
+	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);
+}