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