xref: /illumos-gate/usr/src/uts/common/fs/zfs/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  */
61 static void
62 bookmark_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
73 static void
74 name_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  */
92 void
93 spa_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  */
137 uint64_t
138 spa_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
163 static int
164 process_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 
197 static int
198 process_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  */
230 int
231 spa_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  */
264 void
265 spa_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  */
276 void
277 spa_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  */
299 static void
300 sync_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  */
340 void
341 spa_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