spa_errlog.c revision 148434217c040ea38dc844384f6ba68d9b325906
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 2009 Sun Microsystems, Inc.  All rights reserved.
23 * Use is subject to license terms.
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 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 * This is a stripped-down version of strtoull, suitable only for converting
59 * lowercase hexidecimal numbers that don't overflow.
60 */
61#ifdef _KERNEL
62uint64_t
63strtonum(const char *str, char **nptr)
64{
65	uint64_t val = 0;
66	char c;
67	int digit;
68
69	while ((c = *str) != '\0') {
70		if (c >= '0' && c <= '9')
71			digit = c - '0';
72		else if (c >= 'a' && c <= 'f')
73			digit = 10 + c - 'a';
74		else
75			break;
76
77		val *= 16;
78		val += digit;
79
80		str++;
81	}
82
83	if (nptr)
84		*nptr = (char *)str;
85
86	return (val);
87}
88#endif
89
90/*
91 * Convert a bookmark to a string.
92 */
93static void
94bookmark_to_name(zbookmark_t *zb, char *buf, size_t len)
95{
96	(void) snprintf(buf, len, "%llx:%llx:%llx:%llx",
97	    (u_longlong_t)zb->zb_objset, (u_longlong_t)zb->zb_object,
98	    (u_longlong_t)zb->zb_level, (u_longlong_t)zb->zb_blkid);
99}
100
101/*
102 * Convert a string to a bookmark
103 */
104#ifdef _KERNEL
105static void
106name_to_bookmark(char *buf, zbookmark_t *zb)
107{
108	zb->zb_objset = strtonum(buf, &buf);
109	ASSERT(*buf == ':');
110	zb->zb_object = strtonum(buf + 1, &buf);
111	ASSERT(*buf == ':');
112	zb->zb_level = (int)strtonum(buf + 1, &buf);
113	ASSERT(*buf == ':');
114	zb->zb_blkid = strtonum(buf + 1, &buf);
115	ASSERT(*buf == '\0');
116}
117#endif
118
119/*
120 * Log an uncorrectable error to the persistent error log.  We add it to the
121 * spa's list of pending errors.  The changes are actually synced out to disk
122 * during spa_errlog_sync().
123 */
124void
125spa_log_error(spa_t *spa, zio_t *zio)
126{
127	zbookmark_t *zb = &zio->io_logical->io_bookmark;
128	spa_error_entry_t search;
129	spa_error_entry_t *new;
130	avl_tree_t *tree;
131	avl_index_t where;
132
133	/*
134	 * If we are trying to import a pool, ignore any errors, as we won't be
135	 * writing to the pool any time soon.
136	 */
137	if (spa->spa_load_state == SPA_LOAD_TRYIMPORT)
138		return;
139
140	mutex_enter(&spa->spa_errlist_lock);
141
142	/*
143	 * If we have had a request to rotate the log, log it to the next list
144	 * instead of the current one.
145	 */
146	if (spa->spa_scrub_active || spa->spa_scrub_finished)
147		tree = &spa->spa_errlist_scrub;
148	else
149		tree = &spa->spa_errlist_last;
150
151	search.se_bookmark = *zb;
152	if (avl_find(tree, &search, &where) != NULL) {
153		mutex_exit(&spa->spa_errlist_lock);
154		return;
155	}
156
157	new = kmem_zalloc(sizeof (spa_error_entry_t), KM_SLEEP);
158	new->se_bookmark = *zb;
159	avl_insert(tree, new, where);
160
161	mutex_exit(&spa->spa_errlist_lock);
162}
163
164/*
165 * Return the number of errors currently in the error log.  This is actually the
166 * sum of both the last log and the current log, since we don't know the union
167 * of these logs until we reach userland.
168 */
169uint64_t
170spa_get_errlog_size(spa_t *spa)
171{
172	uint64_t total = 0, count;
173
174	mutex_enter(&spa->spa_errlog_lock);
175	if (spa->spa_errlog_scrub != 0 &&
176	    zap_count(spa->spa_meta_objset, spa->spa_errlog_scrub,
177	    &count) == 0)
178		total += count;
179
180	if (spa->spa_errlog_last != 0 && !spa->spa_scrub_finished &&
181	    zap_count(spa->spa_meta_objset, spa->spa_errlog_last,
182	    &count) == 0)
183		total += count;
184	mutex_exit(&spa->spa_errlog_lock);
185
186	mutex_enter(&spa->spa_errlist_lock);
187	total += avl_numnodes(&spa->spa_errlist_last);
188	total += avl_numnodes(&spa->spa_errlist_scrub);
189	mutex_exit(&spa->spa_errlist_lock);
190
191	return (total);
192}
193
194#ifdef _KERNEL
195static int
196process_error_log(spa_t *spa, uint64_t obj, void *addr, size_t *count)
197{
198	zap_cursor_t zc;
199	zap_attribute_t za;
200	zbookmark_t zb;
201
202	if (obj == 0)
203		return (0);
204
205	for (zap_cursor_init(&zc, spa->spa_meta_objset, obj);
206	    zap_cursor_retrieve(&zc, &za) == 0;
207	    zap_cursor_advance(&zc)) {
208
209		if (*count == 0) {
210			zap_cursor_fini(&zc);
211			return (ENOMEM);
212		}
213
214		name_to_bookmark(za.za_name, &zb);
215
216		if (copyout(&zb, (char *)addr +
217		    (*count - 1) * sizeof (zbookmark_t),
218		    sizeof (zbookmark_t)) != 0)
219			return (EFAULT);
220
221		*count -= 1;
222	}
223
224	zap_cursor_fini(&zc);
225
226	return (0);
227}
228
229static int
230process_error_list(avl_tree_t *list, void *addr, size_t *count)
231{
232	spa_error_entry_t *se;
233
234	for (se = avl_first(list); se != NULL; se = AVL_NEXT(list, se)) {
235
236		if (*count == 0)
237			return (ENOMEM);
238
239		if (copyout(&se->se_bookmark, (char *)addr +
240		    (*count - 1) * sizeof (zbookmark_t),
241		    sizeof (zbookmark_t)) != 0)
242			return (EFAULT);
243
244		*count -= 1;
245	}
246
247	return (0);
248}
249#endif
250
251/*
252 * Copy all known errors to userland as an array of bookmarks.  This is
253 * actually a union of the on-disk last log and current log, as well as any
254 * pending error requests.
255 *
256 * Because the act of reading the on-disk log could cause errors to be
257 * generated, we have two separate locks: one for the error log and one for the
258 * in-core error lists.  We only need the error list lock to log and error, so
259 * we grab the error log lock while we read the on-disk logs, and only pick up
260 * the error list lock when we are finished.
261 */
262int
263spa_get_errlog(spa_t *spa, void *uaddr, size_t *count)
264{
265	int ret = 0;
266
267#ifdef _KERNEL
268	mutex_enter(&spa->spa_errlog_lock);
269
270	ret = process_error_log(spa, spa->spa_errlog_scrub, uaddr, count);
271
272	if (!ret && !spa->spa_scrub_finished)
273		ret = process_error_log(spa, spa->spa_errlog_last, uaddr,
274		    count);
275
276	mutex_enter(&spa->spa_errlist_lock);
277	if (!ret)
278		ret = process_error_list(&spa->spa_errlist_scrub, uaddr,
279		    count);
280	if (!ret)
281		ret = process_error_list(&spa->spa_errlist_last, uaddr,
282		    count);
283	mutex_exit(&spa->spa_errlist_lock);
284
285	mutex_exit(&spa->spa_errlog_lock);
286#endif
287
288	return (ret);
289}
290
291/*
292 * Called when a scrub completes.  This simply set a bit which tells which AVL
293 * tree to add new errors.  spa_errlog_sync() is responsible for actually
294 * syncing the changes to the underlying objects.
295 */
296void
297spa_errlog_rotate(spa_t *spa)
298{
299	mutex_enter(&spa->spa_errlist_lock);
300	spa->spa_scrub_finished = B_TRUE;
301	mutex_exit(&spa->spa_errlist_lock);
302}
303
304/*
305 * Discard any pending errors from the spa_t.  Called when unloading a faulted
306 * pool, as the errors encountered during the open cannot be synced to disk.
307 */
308void
309spa_errlog_drain(spa_t *spa)
310{
311	spa_error_entry_t *se;
312	void *cookie;
313
314	mutex_enter(&spa->spa_errlist_lock);
315
316	cookie = NULL;
317	while ((se = avl_destroy_nodes(&spa->spa_errlist_last,
318	    &cookie)) != NULL)
319		kmem_free(se, sizeof (spa_error_entry_t));
320	cookie = NULL;
321	while ((se = avl_destroy_nodes(&spa->spa_errlist_scrub,
322	    &cookie)) != NULL)
323		kmem_free(se, sizeof (spa_error_entry_t));
324
325	mutex_exit(&spa->spa_errlist_lock);
326}
327
328/*
329 * Process a list of errors into the current on-disk log.
330 */
331static void
332sync_error_list(spa_t *spa, avl_tree_t *t, uint64_t *obj, dmu_tx_t *tx)
333{
334	spa_error_entry_t *se;
335	char buf[64];
336	void *cookie;
337
338	if (avl_numnodes(t) != 0) {
339		/* create log if necessary */
340		if (*obj == 0)
341			*obj = zap_create(spa->spa_meta_objset,
342			    DMU_OT_ERROR_LOG, DMU_OT_NONE,
343			    0, tx);
344
345		/* add errors to the current log */
346		for (se = avl_first(t); se != NULL; se = AVL_NEXT(t, se)) {
347			char *name = se->se_name ? se->se_name : "";
348
349			bookmark_to_name(&se->se_bookmark, buf, sizeof (buf));
350
351			(void) zap_update(spa->spa_meta_objset,
352			    *obj, buf, 1, strlen(name) + 1, name, tx);
353		}
354
355		/* purge the error list */
356		cookie = NULL;
357		while ((se = avl_destroy_nodes(t, &cookie)) != NULL)
358			kmem_free(se, sizeof (spa_error_entry_t));
359	}
360}
361
362/*
363 * Sync the error log out to disk.  This is a little tricky because the act of
364 * writing the error log requires the spa_errlist_lock.  So, we need to lock the
365 * error lists, take a copy of the lists, and then reinitialize them.  Then, we
366 * drop the error list lock and take the error log lock, at which point we
367 * do the errlog processing.  Then, if we encounter an I/O error during this
368 * process, we can successfully add the error to the list.  Note that this will
369 * result in the perpetual recycling of errors, but it is an unlikely situation
370 * and not a performance critical operation.
371 */
372void
373spa_errlog_sync(spa_t *spa, uint64_t txg)
374{
375	dmu_tx_t *tx;
376	avl_tree_t scrub, last;
377	int scrub_finished;
378
379	mutex_enter(&spa->spa_errlist_lock);
380
381	/*
382	 * Bail out early under normal circumstances.
383	 */
384	if (avl_numnodes(&spa->spa_errlist_scrub) == 0 &&
385	    avl_numnodes(&spa->spa_errlist_last) == 0 &&
386	    !spa->spa_scrub_finished) {
387		mutex_exit(&spa->spa_errlist_lock);
388		return;
389	}
390
391	spa_get_errlists(spa, &last, &scrub);
392	scrub_finished = spa->spa_scrub_finished;
393	spa->spa_scrub_finished = B_FALSE;
394
395	mutex_exit(&spa->spa_errlist_lock);
396	mutex_enter(&spa->spa_errlog_lock);
397
398	tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
399
400	/*
401	 * Sync out the current list of errors.
402	 */
403	sync_error_list(spa, &last, &spa->spa_errlog_last, tx);
404
405	/*
406	 * Rotate the log if necessary.
407	 */
408	if (scrub_finished) {
409		if (spa->spa_errlog_last != 0)
410			VERIFY(dmu_object_free(spa->spa_meta_objset,
411			    spa->spa_errlog_last, tx) == 0);
412		spa->spa_errlog_last = spa->spa_errlog_scrub;
413		spa->spa_errlog_scrub = 0;
414
415		sync_error_list(spa, &scrub, &spa->spa_errlog_last, tx);
416	}
417
418	/*
419	 * Sync out any pending scrub errors.
420	 */
421	sync_error_list(spa, &scrub, &spa->spa_errlog_scrub, tx);
422
423	/*
424	 * Update the MOS to reflect the new values.
425	 */
426	(void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
427	    DMU_POOL_ERRLOG_LAST, sizeof (uint64_t), 1,
428	    &spa->spa_errlog_last, tx);
429	(void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
430	    DMU_POOL_ERRLOG_SCRUB, sizeof (uint64_t), 1,
431	    &spa->spa_errlog_scrub, tx);
432
433	dmu_tx_commit(tx);
434
435	mutex_exit(&spa->spa_errlog_lock);
436}
437