xref: /illumos-gate/usr/src/uts/common/fs/zfs/spa_errlog.c (revision eb633035)
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, 2014 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_phys 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
bookmark_to_name(zbookmark_phys_t * zb,char * buf,size_t len)62 bookmark_to_name(zbookmark_phys_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
name_to_bookmark(char * buf,zbookmark_phys_t * zb)74 name_to_bookmark(char *buf, zbookmark_phys_t *zb)
75 {
76 	zb->zb_objset = zfs_strtonum(buf, &buf);
77 	ASSERT(*buf == ':');
78 	zb->zb_object = zfs_strtonum(buf + 1, &buf);
79 	ASSERT(*buf == ':');
80 	zb->zb_level = (int)zfs_strtonum(buf + 1, &buf);
81 	ASSERT(*buf == ':');
82 	zb->zb_blkid = zfs_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
spa_log_error(spa_t * spa,const zbookmark_phys_t * zb)93 spa_log_error(spa_t *spa, const zbookmark_phys_t *zb)
94 {
95 	spa_error_entry_t search;
96 	spa_error_entry_t *new;
97 	avl_tree_t *tree;
98 	avl_index_t where;
99 
100 	/*
101 	 * If we are trying to import a pool, ignore any errors, as we won't be
102 	 * writing to the pool any time soon.
103 	 */
104 	if (spa_load_state(spa) == SPA_LOAD_TRYIMPORT)
105 		return;
106 
107 	mutex_enter(&spa->spa_errlist_lock);
108 
109 	/*
110 	 * If we have had a request to rotate the log, log it to the next list
111 	 * instead of the current one.
112 	 */
113 	if (spa->spa_scrub_active || spa->spa_scrub_finished)
114 		tree = &spa->spa_errlist_scrub;
115 	else
116 		tree = &spa->spa_errlist_last;
117 
118 	search.se_bookmark = *zb;
119 	if (avl_find(tree, &search, &where) != NULL) {
120 		mutex_exit(&spa->spa_errlist_lock);
121 		return;
122 	}
123 
124 	new = kmem_zalloc(sizeof (spa_error_entry_t), KM_SLEEP);
125 	new->se_bookmark = *zb;
126 	avl_insert(tree, new, where);
127 
128 	mutex_exit(&spa->spa_errlist_lock);
129 }
130 
131 /*
132  * Return the number of errors currently in the error log.  This is actually the
133  * sum of both the last log and the current log, since we don't know the union
134  * of these logs until we reach userland.
135  */
136 uint64_t
spa_get_errlog_size(spa_t * spa)137 spa_get_errlog_size(spa_t *spa)
138 {
139 	uint64_t total = 0, count;
140 
141 	mutex_enter(&spa->spa_errlog_lock);
142 	if (spa->spa_errlog_scrub != 0 &&
143 	    zap_count(spa->spa_meta_objset, spa->spa_errlog_scrub,
144 	    &count) == 0)
145 		total += count;
146 
147 	if (spa->spa_errlog_last != 0 && !spa->spa_scrub_finished &&
148 	    zap_count(spa->spa_meta_objset, spa->spa_errlog_last,
149 	    &count) == 0)
150 		total += count;
151 	mutex_exit(&spa->spa_errlog_lock);
152 
153 	mutex_enter(&spa->spa_errlist_lock);
154 	total += avl_numnodes(&spa->spa_errlist_last);
155 	total += avl_numnodes(&spa->spa_errlist_scrub);
156 	mutex_exit(&spa->spa_errlist_lock);
157 
158 	return (total);
159 }
160 
161 #ifdef _KERNEL
162 static int
process_error_log(spa_t * spa,uint64_t obj,void * addr,size_t * count)163 process_error_log(spa_t *spa, uint64_t obj, void *addr, size_t *count)
164 {
165 	zap_cursor_t zc;
166 	zap_attribute_t za;
167 	zbookmark_phys_t zb;
168 
169 	if (obj == 0)
170 		return (0);
171 
172 	for (zap_cursor_init(&zc, spa->spa_meta_objset, obj);
173 	    zap_cursor_retrieve(&zc, &za) == 0;
174 	    zap_cursor_advance(&zc)) {
175 
176 		if (*count == 0) {
177 			zap_cursor_fini(&zc);
178 			return (SET_ERROR(ENOMEM));
179 		}
180 
181 		name_to_bookmark(za.za_name, &zb);
182 
183 		if (copyout(&zb, (char *)addr +
184 		    (*count - 1) * sizeof (zbookmark_phys_t),
185 		    sizeof (zbookmark_phys_t)) != 0) {
186 			zap_cursor_fini(&zc);
187 			return (SET_ERROR(EFAULT));
188 		}
189 
190 		*count -= 1;
191 	}
192 
193 	zap_cursor_fini(&zc);
194 
195 	return (0);
196 }
197 
198 static int
process_error_list(avl_tree_t * list,void * addr,size_t * count)199 process_error_list(avl_tree_t *list, void *addr, size_t *count)
200 {
201 	spa_error_entry_t *se;
202 
203 	for (se = avl_first(list); se != NULL; se = AVL_NEXT(list, se)) {
204 
205 		if (*count == 0)
206 			return (SET_ERROR(ENOMEM));
207 
208 		if (copyout(&se->se_bookmark, (char *)addr +
209 		    (*count - 1) * sizeof (zbookmark_phys_t),
210 		    sizeof (zbookmark_phys_t)) != 0)
211 			return (SET_ERROR(EFAULT));
212 
213 		*count -= 1;
214 	}
215 
216 	return (0);
217 }
218 #endif
219 
220 /*
221  * Copy all known errors to userland as an array of bookmarks.  This is
222  * actually a union of the on-disk last log and current log, as well as any
223  * pending error requests.
224  *
225  * Because the act of reading the on-disk log could cause errors to be
226  * generated, we have two separate locks: one for the error log and one for the
227  * in-core error lists.  We only need the error list lock to log and error, so
228  * we grab the error log lock while we read the on-disk logs, and only pick up
229  * the error list lock when we are finished.
230  */
231 int
spa_get_errlog(spa_t * spa,void * uaddr,size_t * count)232 spa_get_errlog(spa_t *spa, void *uaddr, size_t *count)
233 {
234 	int ret = 0;
235 
236 #ifdef _KERNEL
237 	mutex_enter(&spa->spa_errlog_lock);
238 
239 	ret = process_error_log(spa, spa->spa_errlog_scrub, uaddr, count);
240 
241 	if (!ret && !spa->spa_scrub_finished)
242 		ret = process_error_log(spa, spa->spa_errlog_last, uaddr,
243 		    count);
244 
245 	mutex_enter(&spa->spa_errlist_lock);
246 	if (!ret)
247 		ret = process_error_list(&spa->spa_errlist_scrub, uaddr,
248 		    count);
249 	if (!ret)
250 		ret = process_error_list(&spa->spa_errlist_last, uaddr,
251 		    count);
252 	mutex_exit(&spa->spa_errlist_lock);
253 
254 	mutex_exit(&spa->spa_errlog_lock);
255 #endif
256 
257 	return (ret);
258 }
259 
260 /*
261  * Called when a scrub completes.  This simply set a bit which tells which AVL
262  * tree to add new errors.  spa_errlog_sync() is responsible for actually
263  * syncing the changes to the underlying objects.
264  */
265 void
spa_errlog_rotate(spa_t * spa)266 spa_errlog_rotate(spa_t *spa)
267 {
268 	mutex_enter(&spa->spa_errlist_lock);
269 	spa->spa_scrub_finished = B_TRUE;
270 	mutex_exit(&spa->spa_errlist_lock);
271 }
272 
273 /*
274  * Discard any pending errors from the spa_t.  Called when unloading a faulted
275  * pool, as the errors encountered during the open cannot be synced to disk.
276  */
277 void
spa_errlog_drain(spa_t * spa)278 spa_errlog_drain(spa_t *spa)
279 {
280 	spa_error_entry_t *se;
281 	void *cookie;
282 
283 	mutex_enter(&spa->spa_errlist_lock);
284 
285 	cookie = NULL;
286 	while ((se = avl_destroy_nodes(&spa->spa_errlist_last,
287 	    &cookie)) != NULL)
288 		kmem_free(se, sizeof (spa_error_entry_t));
289 	cookie = NULL;
290 	while ((se = avl_destroy_nodes(&spa->spa_errlist_scrub,
291 	    &cookie)) != NULL)
292 		kmem_free(se, sizeof (spa_error_entry_t));
293 
294 	mutex_exit(&spa->spa_errlist_lock);
295 }
296 
297 /*
298  * Process a list of errors into the current on-disk log.
299  */
300 static void
sync_error_list(spa_t * spa,avl_tree_t * t,uint64_t * obj,dmu_tx_t * tx)301 sync_error_list(spa_t *spa, avl_tree_t *t, uint64_t *obj, dmu_tx_t *tx)
302 {
303 	spa_error_entry_t *se;
304 	char buf[64];
305 	void *cookie;
306 
307 	if (avl_numnodes(t) != 0) {
308 		/* create log if necessary */
309 		if (*obj == 0)
310 			*obj = zap_create(spa->spa_meta_objset,
311 			    DMU_OT_ERROR_LOG, DMU_OT_NONE,
312 			    0, tx);
313 
314 		/* add errors to the current log */
315 		for (se = avl_first(t); se != NULL; se = AVL_NEXT(t, se)) {
316 			char *name = se->se_name ? se->se_name : "";
317 
318 			bookmark_to_name(&se->se_bookmark, buf, sizeof (buf));
319 
320 			(void) zap_update(spa->spa_meta_objset,
321 			    *obj, buf, 1, strlen(name) + 1, name, tx);
322 		}
323 
324 		/* purge the error list */
325 		cookie = NULL;
326 		while ((se = avl_destroy_nodes(t, &cookie)) != NULL)
327 			kmem_free(se, sizeof (spa_error_entry_t));
328 	}
329 }
330 
331 /*
332  * Sync the error log out to disk.  This is a little tricky because the act of
333  * writing the error log requires the spa_errlist_lock.  So, we need to lock the
334  * error lists, take a copy of the lists, and then reinitialize them.  Then, we
335  * drop the error list lock and take the error log lock, at which point we
336  * do the errlog processing.  Then, if we encounter an I/O error during this
337  * process, we can successfully add the error to the list.  Note that this will
338  * result in the perpetual recycling of errors, but it is an unlikely situation
339  * and not a performance critical operation.
340  */
341 void
spa_errlog_sync(spa_t * spa,uint64_t txg)342 spa_errlog_sync(spa_t *spa, uint64_t txg)
343 {
344 	dmu_tx_t *tx;
345 	avl_tree_t scrub, last;
346 	int scrub_finished;
347 
348 	mutex_enter(&spa->spa_errlist_lock);
349 
350 	/*
351 	 * Bail out early under normal circumstances.
352 	 */
353 	if (avl_numnodes(&spa->spa_errlist_scrub) == 0 &&
354 	    avl_numnodes(&spa->spa_errlist_last) == 0 &&
355 	    !spa->spa_scrub_finished) {
356 		mutex_exit(&spa->spa_errlist_lock);
357 		return;
358 	}
359 
360 	spa_get_errlists(spa, &last, &scrub);
361 	scrub_finished = spa->spa_scrub_finished;
362 	spa->spa_scrub_finished = B_FALSE;
363 
364 	mutex_exit(&spa->spa_errlist_lock);
365 	mutex_enter(&spa->spa_errlog_lock);
366 
367 	tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
368 
369 	/*
370 	 * Sync out the current list of errors.
371 	 */
372 	sync_error_list(spa, &last, &spa->spa_errlog_last, tx);
373 
374 	/*
375 	 * Rotate the log if necessary.
376 	 */
377 	if (scrub_finished) {
378 		if (spa->spa_errlog_last != 0)
379 			VERIFY(dmu_object_free(spa->spa_meta_objset,
380 			    spa->spa_errlog_last, tx) == 0);
381 		spa->spa_errlog_last = spa->spa_errlog_scrub;
382 		spa->spa_errlog_scrub = 0;
383 
384 		sync_error_list(spa, &scrub, &spa->spa_errlog_last, tx);
385 	}
386 
387 	/*
388 	 * Sync out any pending scrub errors.
389 	 */
390 	sync_error_list(spa, &scrub, &spa->spa_errlog_scrub, tx);
391 
392 	/*
393 	 * Update the MOS to reflect the new values.
394 	 */
395 	(void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
396 	    DMU_POOL_ERRLOG_LAST, sizeof (uint64_t), 1,
397 	    &spa->spa_errlog_last, tx);
398 	(void) zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
399 	    DMU_POOL_ERRLOG_SCRUB, sizeof (uint64_t), 1,
400 	    &spa->spa_errlog_scrub, tx);
401 
402 	dmu_tx_commit(tx);
403 
404 	mutex_exit(&spa->spa_errlog_lock);
405 }
406