/*

 * 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 2009 Sun Microsystems, Inc.  All rights reserved.

 * Use is subject to license terms.

 */

/*

 * 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.

 */

uint64_t

strtonum(const 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++;

	}

	if (nptr)

		*nptr = (char *)str;

	return (val);

}

/*

 * 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);

	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);

}