spa_errlog.c revision be6fd75a69ae679453d9cda5bff3326111e6d1ca
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 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 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 */
61static void
62bookmark_to_name(zbookmark_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
73static void
74name_to_bookmark(char *buf, zbookmark_t *zb)
75{
76	zb->zb_objset = strtonum(buf, &buf);
77	ASSERT(*buf == ':');
78	zb->zb_object = strtonum(buf + 1, &buf);
79	ASSERT(*buf == ':');
80	zb->zb_level = (int)strtonum(buf + 1, &buf);
81	ASSERT(*buf == ':');
82	zb->zb_blkid = 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 */
92void
93spa_log_error(spa_t *spa, zio_t *zio)
94{
95	zbookmark_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 */
137uint64_t
138spa_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
163static int
164process_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_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_t),
186		    sizeof (zbookmark_t)) != 0)
187			return (SET_ERROR(EFAULT));
188
189		*count -= 1;
190	}
191
192	zap_cursor_fini(&zc);
193
194	return (0);
195}
196
197static int
198process_error_list(avl_tree_t *list, void *addr, size_t *count)
199{
200	spa_error_entry_t *se;
201
202	for (se = avl_first(list); se != NULL; se = AVL_NEXT(list, se)) {
203
204		if (*count == 0)
205			return (SET_ERROR(ENOMEM));
206
207		if (copyout(&se->se_bookmark, (char *)addr +
208		    (*count - 1) * sizeof (zbookmark_t),
209		    sizeof (zbookmark_t)) != 0)
210			return (SET_ERROR(EFAULT));
211
212		*count -= 1;
213	}
214
215	return (0);
216}
217#endif
218
219/*
220 * Copy all known errors to userland as an array of bookmarks.  This is
221 * actually a union of the on-disk last log and current log, as well as any
222 * pending error requests.
223 *
224 * Because the act of reading the on-disk log could cause errors to be
225 * generated, we have two separate locks: one for the error log and one for the
226 * in-core error lists.  We only need the error list lock to log and error, so
227 * we grab the error log lock while we read the on-disk logs, and only pick up
228 * the error list lock when we are finished.
229 */
230int
231spa_get_errlog(spa_t *spa, void *uaddr, size_t *count)
232{
233	int ret = 0;
234
235#ifdef _KERNEL
236	mutex_enter(&spa->spa_errlog_lock);
237
238	ret = process_error_log(spa, spa->spa_errlog_scrub, uaddr, count);
239
240	if (!ret && !spa->spa_scrub_finished)
241		ret = process_error_log(spa, spa->spa_errlog_last, uaddr,
242		    count);
243
244	mutex_enter(&spa->spa_errlist_lock);
245	if (!ret)
246		ret = process_error_list(&spa->spa_errlist_scrub, uaddr,
247		    count);
248	if (!ret)
249		ret = process_error_list(&spa->spa_errlist_last, uaddr,
250		    count);
251	mutex_exit(&spa->spa_errlist_lock);
252
253	mutex_exit(&spa->spa_errlog_lock);
254#endif
255
256	return (ret);
257}
258
259/*
260 * Called when a scrub completes.  This simply set a bit which tells which AVL
261 * tree to add new errors.  spa_errlog_sync() is responsible for actually
262 * syncing the changes to the underlying objects.
263 */
264void
265spa_errlog_rotate(spa_t *spa)
266{
267	mutex_enter(&spa->spa_errlist_lock);
268	spa->spa_scrub_finished = B_TRUE;
269	mutex_exit(&spa->spa_errlist_lock);
270}
271
272/*
273 * Discard any pending errors from the spa_t.  Called when unloading a faulted
274 * pool, as the errors encountered during the open cannot be synced to disk.
275 */
276void
277spa_errlog_drain(spa_t *spa)
278{
279	spa_error_entry_t *se;
280	void *cookie;
281
282	mutex_enter(&spa->spa_errlist_lock);
283
284	cookie = NULL;
285	while ((se = avl_destroy_nodes(&spa->spa_errlist_last,
286	    &cookie)) != NULL)
287		kmem_free(se, sizeof (spa_error_entry_t));
288	cookie = NULL;
289	while ((se = avl_destroy_nodes(&spa->spa_errlist_scrub,
290	    &cookie)) != NULL)
291		kmem_free(se, sizeof (spa_error_entry_t));
292
293	mutex_exit(&spa->spa_errlist_lock);
294}
295
296/*
297 * Process a list of errors into the current on-disk log.
298 */
299static void
300sync_error_list(spa_t *spa, avl_tree_t *t, uint64_t *obj, dmu_tx_t *tx)
301{
302	spa_error_entry_t *se;
303	char buf[64];
304	void *cookie;
305
306	if (avl_numnodes(t) != 0) {
307		/* create log if necessary */
308		if (*obj == 0)
309			*obj = zap_create(spa->spa_meta_objset,
310			    DMU_OT_ERROR_LOG, DMU_OT_NONE,
311			    0, tx);
312
313		/* add errors to the current log */
314		for (se = avl_first(t); se != NULL; se = AVL_NEXT(t, se)) {
315			char *name = se->se_name ? se->se_name : "";
316
317			bookmark_to_name(&se->se_bookmark, buf, sizeof (buf));
318
319			(void) zap_update(spa->spa_meta_objset,
320			    *obj, buf, 1, strlen(name) + 1, name, tx);
321		}
322
323		/* purge the error list */
324		cookie = NULL;
325		while ((se = avl_destroy_nodes(t, &cookie)) != NULL)
326			kmem_free(se, sizeof (spa_error_entry_t));
327	}
328}
329
330/*
331 * Sync the error log out to disk.  This is a little tricky because the act of
332 * writing the error log requires the spa_errlist_lock.  So, we need to lock the
333 * error lists, take a copy of the lists, and then reinitialize them.  Then, we
334 * drop the error list lock and take the error log lock, at which point we
335 * do the errlog processing.  Then, if we encounter an I/O error during this
336 * process, we can successfully add the error to the list.  Note that this will
337 * result in the perpetual recycling of errors, but it is an unlikely situation
338 * and not a performance critical operation.
339 */
340void
341spa_errlog_sync(spa_t *spa, uint64_t txg)
342{
343	dmu_tx_t *tx;
344	avl_tree_t scrub, last;
345	int scrub_finished;
346
347	mutex_enter(&spa->spa_errlist_lock);
348
349	/*
350	 * Bail out early under normal circumstances.
351	 */
352	if (avl_numnodes(&spa->spa_errlist_scrub) == 0 &&
353	    avl_numnodes(&spa->spa_errlist_last) == 0 &&
354	    !spa->spa_scrub_finished) {
355		mutex_exit(&spa->spa_errlist_lock);
356		return;
357	}
358
359	spa_get_errlists(spa, &last, &scrub);
360	scrub_finished = spa->spa_scrub_finished;
361	spa->spa_scrub_finished = B_FALSE;
362
363	mutex_exit(&spa->spa_errlist_lock);
364	mutex_enter(&spa->spa_errlog_lock);
365
366	tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
367
368	/*
369	 * Sync out the current list of errors.
370	 */
371	sync_error_list(spa, &last, &spa->spa_errlog_last, tx);
372
373	/*
374	 * Rotate the log if necessary.
375	 */
376	if (scrub_finished) {
377		if (spa->spa_errlog_last != 0)
378			VERIFY(dmu_object_free(spa->spa_meta_objset,
379			    spa->spa_errlog_last, tx) == 0);
380		spa->spa_errlog_last = spa->spa_errlog_scrub;
381		spa->spa_errlog_scrub = 0;
382
383		sync_error_list(spa, &scrub, &spa->spa_errlog_last, tx);
384	}
385
386	/*
387	 * Sync out any pending scrub errors.
388	 */
389	sync_error_list(spa, &scrub, &spa->spa_errlog_scrub, tx);
390
391	/*
392	 * Update the MOS to reflect the new values.
393	 */
394	(void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
395	    DMU_POOL_ERRLOG_LAST, sizeof (uint64_t), 1,
396	    &spa->spa_errlog_last, tx);
397	(void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
398	    DMU_POOL_ERRLOG_SCRUB, sizeof (uint64_t), 1,
399	    &spa->spa_errlog_scrub, tx);
400
401	dmu_tx_commit(tx);
402
403	mutex_exit(&spa->spa_errlog_lock);
404}
405