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) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23  * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
24  */
25 
26 /*
27  * ZFS fault injection
28  *
29  * To handle fault injection, we keep track of a series of zinject_record_t
30  * structures which describe which logical block(s) should be injected with a
31  * fault.  These are kept in a global list.  Each record corresponds to a given
32  * spa_t and maintains a special hold on the spa_t so that it cannot be deleted
33  * or exported while the injection record exists.
34  *
35  * Device level injection is done using the 'zi_guid' field.  If this is set, it
36  * means that the error is destined for a particular device, not a piece of
37  * data.
38  *
39  * This is a rather poor data structure and algorithm, but we don't expect more
40  * than a few faults at any one time, so it should be sufficient for our needs.
41  */
42 
43 #include <sys/arc.h>
44 #include <sys/zio_impl.h>
45 #include <sys/zfs_ioctl.h>
46 #include <sys/vdev_impl.h>
47 #include <sys/dmu_objset.h>
48 #include <sys/fs/zfs.h>
49 
50 uint32_t zio_injection_enabled;
51 
52 /*
53  * Data describing each zinject handler registered on the system, and
54  * contains the list node linking the handler in the global zinject
55  * handler list.
56  */
57 typedef struct inject_handler {
58           int                           zi_id;
59           spa_t                         *zi_spa;
60           zinject_record_t    zi_record;
61           uint64_t            *zi_lanes;
62           int                           zi_next_lane;
63           list_node_t                   zi_link;
64 } inject_handler_t;
65 
66 /*
67  * List of all zinject handlers registered on the system, protected by
68  * the inject_lock defined below.
69  */
70 static list_t inject_handlers;
71 
72 /*
73  * This protects insertion into, and traversal of, the inject handler
74  * list defined above; as well as the inject_delay_count. Any time a
75  * handler is inserted or removed from the list, this lock should be
76  * taken as a RW_WRITER; and any time traversal is done over the list
77  * (without modification to it) this lock should be taken as a RW_READER.
78  */
79 static krwlock_t inject_lock;
80 
81 /*
82  * This holds the number of zinject delay handlers that have been
83  * registered on the system. It is protected by the inject_lock defined
84  * above. Thus modifications to this count must be a RW_WRITER of the
85  * inject_lock, and reads of this count must be (at least) a RW_READER
86  * of the lock.
87  */
88 static int inject_delay_count = 0;
89 
90 /*
91  * This lock is used only in zio_handle_io_delay(), refer to the comment
92  * in that function for more details.
93  */
94 static kmutex_t inject_delay_mtx;
95 
96 /*
97  * Used to assign unique identifying numbers to each new zinject handler.
98  */
99 static int inject_next_id = 1;
100 
101 /*
102  * Returns true if the given record matches the I/O in progress.
103  */
104 static boolean_t
zio_match_handler(zbookmark_phys_t * zb,uint64_t type,zinject_record_t * record,int error)105 zio_match_handler(zbookmark_phys_t *zb, uint64_t type,
106     zinject_record_t *record, int error)
107 {
108           /*
109            * Check for a match against the MOS, which is based on type
110            */
111           if (zb->zb_objset == DMU_META_OBJSET &&
112               record->zi_objset == DMU_META_OBJSET &&
113               record->zi_object == DMU_META_DNODE_OBJECT) {
114                     if (record->zi_type == DMU_OT_NONE ||
115                         type == record->zi_type)
116                               return (record->zi_freq == 0 ||
117                                   spa_get_random(100) < record->zi_freq);
118                     else
119                               return (B_FALSE);
120           }
121 
122           /*
123            * Check for an exact match.
124            */
125           if (zb->zb_objset == record->zi_objset &&
126               zb->zb_object == record->zi_object &&
127               zb->zb_level == record->zi_level &&
128               zb->zb_blkid >= record->zi_start &&
129               zb->zb_blkid <= record->zi_end &&
130               error == record->zi_error)
131                     return (record->zi_freq == 0 ||
132                         spa_get_random(100) < record->zi_freq);
133 
134           return (B_FALSE);
135 }
136 
137 /*
138  * Panic the system when a config change happens in the function
139  * specified by tag.
140  */
141 void
zio_handle_panic_injection(spa_t * spa,char * tag,uint64_t type)142 zio_handle_panic_injection(spa_t *spa, char *tag, uint64_t type)
143 {
144           inject_handler_t *handler;
145 
146           rw_enter(&inject_lock, RW_READER);
147 
148           for (handler = list_head(&inject_handlers); handler != NULL;
149               handler = list_next(&inject_handlers, handler)) {
150 
151                     if (spa != handler->zi_spa)
152                               continue;
153 
154                     if (handler->zi_record.zi_type == type &&
155                         strcmp(tag, handler->zi_record.zi_func) == 0)
156                               panic("Panic requested in function %s\n", tag);
157           }
158 
159           rw_exit(&inject_lock);
160 }
161 
162 /*
163  * Determine if the I/O in question should return failure.  Returns the errno
164  * to be returned to the caller.
165  */
166 int
zio_handle_fault_injection(zio_t * zio,int error)167 zio_handle_fault_injection(zio_t *zio, int error)
168 {
169           int ret = 0;
170           inject_handler_t *handler;
171 
172           /*
173            * Ignore I/O not associated with any logical data.
174            */
175           if (zio->io_logical == NULL)
176                     return (0);
177 
178           /*
179            * Currently, we only support fault injection on reads.
180            */
181           if (zio->io_type != ZIO_TYPE_READ)
182                     return (0);
183 
184           rw_enter(&inject_lock, RW_READER);
185 
186           for (handler = list_head(&inject_handlers); handler != NULL;
187               handler = list_next(&inject_handlers, handler)) {
188 
189                     if (zio->io_spa != handler->zi_spa ||
190                         handler->zi_record.zi_cmd != ZINJECT_DATA_FAULT)
191                               continue;
192 
193                     /* If this handler matches, return EIO */
194                     if (zio_match_handler(&zio->io_logical->io_bookmark,
195                         zio->io_bp ? BP_GET_TYPE(zio->io_bp) : DMU_OT_NONE,
196                         &handler->zi_record, error)) {
197                               ret = error;
198                               break;
199                     }
200           }
201 
202           rw_exit(&inject_lock);
203 
204           return (ret);
205 }
206 
207 /*
208  * Determine if the zio is part of a label update and has an injection
209  * handler associated with that portion of the label. Currently, we
210  * allow error injection in either the nvlist or the uberblock region of
211  * of the vdev label.
212  */
213 int
zio_handle_label_injection(zio_t * zio,int error)214 zio_handle_label_injection(zio_t *zio, int error)
215 {
216           inject_handler_t *handler;
217           vdev_t *vd = zio->io_vd;
218           uint64_t offset = zio->io_offset;
219           int label;
220           int ret = 0;
221 
222           if (offset >= VDEV_LABEL_START_SIZE &&
223               offset < vd->vdev_psize - VDEV_LABEL_END_SIZE)
224                     return (0);
225 
226           rw_enter(&inject_lock, RW_READER);
227 
228           for (handler = list_head(&inject_handlers); handler != NULL;
229               handler = list_next(&inject_handlers, handler)) {
230                     uint64_t start = handler->zi_record.zi_start;
231                     uint64_t end = handler->zi_record.zi_end;
232 
233                     if (handler->zi_record.zi_cmd != ZINJECT_LABEL_FAULT)
234                               continue;
235 
236                     /*
237                      * The injection region is the relative offsets within a
238                      * vdev label. We must determine the label which is being
239                      * updated and adjust our region accordingly.
240                      */
241                     label = vdev_label_number(vd->vdev_psize, offset);
242                     start = vdev_label_offset(vd->vdev_psize, label, start);
243                     end = vdev_label_offset(vd->vdev_psize, label, end);
244 
245                     if (zio->io_vd->vdev_guid == handler->zi_record.zi_guid &&
246                         (offset >= start && offset <= end)) {
247                               ret = error;
248                               break;
249                     }
250           }
251           rw_exit(&inject_lock);
252           return (ret);
253 }
254 
255 
256 int
zio_handle_device_injection(vdev_t * vd,zio_t * zio,int error)257 zio_handle_device_injection(vdev_t *vd, zio_t *zio, int error)
258 {
259           inject_handler_t *handler;
260           int ret = 0;
261 
262           /*
263            * We skip over faults in the labels unless it's during
264            * device open (i.e. zio == NULL).
265            */
266           if (zio != NULL) {
267                     uint64_t offset = zio->io_offset;
268 
269                     if (offset < VDEV_LABEL_START_SIZE ||
270                         offset >= vd->vdev_psize - VDEV_LABEL_END_SIZE)
271                               return (0);
272           }
273 
274           rw_enter(&inject_lock, RW_READER);
275 
276           for (handler = list_head(&inject_handlers); handler != NULL;
277               handler = list_next(&inject_handlers, handler)) {
278 
279                     if (handler->zi_record.zi_cmd != ZINJECT_DEVICE_FAULT)
280                               continue;
281 
282                     if (vd->vdev_guid == handler->zi_record.zi_guid) {
283                               if (handler->zi_record.zi_failfast &&
284                                   (zio == NULL || (zio->io_flags &
285                                   (ZIO_FLAG_IO_RETRY | ZIO_FLAG_TRYHARD)))) {
286                                         continue;
287                               }
288 
289                               /* Handle type specific I/O failures */
290                               if (zio != NULL &&
291                                   handler->zi_record.zi_iotype != ZIO_TYPES &&
292                                   handler->zi_record.zi_iotype != zio->io_type)
293                                         continue;
294 
295                               if (handler->zi_record.zi_error == error) {
296                                         /*
297                                          * For a failed open, pretend like the device
298                                          * has gone away.
299                                          */
300                                         if (error == ENXIO)
301                                                   vd->vdev_stat.vs_aux =
302                                                       VDEV_AUX_OPEN_FAILED;
303 
304                                         /*
305                                          * Treat these errors as if they had been
306                                          * retried so that all the appropriate stats
307                                          * and FMA events are generated.
308                                          */
309                                         if (!handler->zi_record.zi_failfast &&
310                                             zio != NULL)
311                                                   zio->io_flags |= ZIO_FLAG_IO_RETRY;
312 
313                                         ret = error;
314                                         break;
315                               }
316                               if (handler->zi_record.zi_error == ENXIO) {
317                                         ret = SET_ERROR(EIO);
318                                         break;
319                               }
320                     }
321           }
322 
323           rw_exit(&inject_lock);
324 
325           return (ret);
326 }
327 
328 /*
329  * Simulate hardware that ignores cache flushes.  For requested number
330  * of seconds nix the actual writing to disk.
331  */
332 void
zio_handle_ignored_writes(zio_t * zio)333 zio_handle_ignored_writes(zio_t *zio)
334 {
335           inject_handler_t *handler;
336 
337           rw_enter(&inject_lock, RW_READER);
338 
339           for (handler = list_head(&inject_handlers); handler != NULL;
340               handler = list_next(&inject_handlers, handler)) {
341 
342                     /* Ignore errors not destined for this pool */
343                     if (zio->io_spa != handler->zi_spa ||
344                         handler->zi_record.zi_cmd != ZINJECT_IGNORED_WRITES)
345                               continue;
346 
347                     /*
348                      * Positive duration implies # of seconds, negative
349                      * a number of txgs
350                      */
351                     if (handler->zi_record.zi_timer == 0) {
352                               if (handler->zi_record.zi_duration > 0)
353                                         handler->zi_record.zi_timer = ddi_get_lbolt64();
354                               else
355                                         handler->zi_record.zi_timer = zio->io_txg;
356                     }
357 
358                     /* Have a "problem" writing 60% of the time */
359                     if (spa_get_random(100) < 60)
360                               zio->io_pipeline &= ~ZIO_VDEV_IO_STAGES;
361                     break;
362           }
363 
364           rw_exit(&inject_lock);
365 }
366 
367 void
spa_handle_ignored_writes(spa_t * spa)368 spa_handle_ignored_writes(spa_t *spa)
369 {
370           inject_handler_t *handler;
371 
372           if (zio_injection_enabled == 0)
373                     return;
374 
375           rw_enter(&inject_lock, RW_READER);
376 
377           for (handler = list_head(&inject_handlers); handler != NULL;
378               handler = list_next(&inject_handlers, handler)) {
379 
380                     if (spa != handler->zi_spa ||
381                         handler->zi_record.zi_cmd != ZINJECT_IGNORED_WRITES)
382                               continue;
383 
384                     if (handler->zi_record.zi_duration > 0) {
385                               VERIFY(handler->zi_record.zi_timer == 0 ||
386                                   handler->zi_record.zi_timer +
387                                   handler->zi_record.zi_duration * hz >
388                                   ddi_get_lbolt64());
389                     } else {
390                               /* duration is negative so the subtraction here adds */
391                               VERIFY(handler->zi_record.zi_timer == 0 ||
392                                   handler->zi_record.zi_timer -
393                                   handler->zi_record.zi_duration >=
394                                   spa_syncing_txg(spa));
395                     }
396           }
397 
398           rw_exit(&inject_lock);
399 }
400 
401 hrtime_t
zio_handle_io_delay(zio_t * zio)402 zio_handle_io_delay(zio_t *zio)
403 {
404           vdev_t *vd = zio->io_vd;
405           inject_handler_t *min_handler = NULL;
406           hrtime_t min_target = 0;
407 
408           rw_enter(&inject_lock, RW_READER);
409 
410           /*
411            * inject_delay_count is a subset of zio_injection_enabled that
412            * is only incremented for delay handlers. These checks are
413            * mainly added to remind the reader why we're not explicitly
414            * checking zio_injection_enabled like the other functions.
415            */
416           IMPLY(inject_delay_count > 0, zio_injection_enabled > 0);
417           IMPLY(zio_injection_enabled == 0, inject_delay_count == 0);
418 
419           /*
420            * If there aren't any inject delay handlers registered, then we
421            * can short circuit and simply return 0 here. A value of zero
422            * informs zio_delay_interrupt() that this request should not be
423            * delayed. This short circuit keeps us from acquiring the
424            * inject_delay_mutex unnecessarily.
425            */
426           if (inject_delay_count == 0) {
427                     rw_exit(&inject_lock);
428                     return (0);
429           }
430 
431           /*
432            * Each inject handler has a number of "lanes" associated with
433            * it. Each lane is able to handle requests independently of one
434            * another, and at a latency defined by the inject handler
435            * record's zi_timer field. Thus if a handler in configured with
436            * a single lane with a 10ms latency, it will delay requests
437            * such that only a single request is completed every 10ms. So,
438            * if more than one request is attempted per each 10ms interval,
439            * the average latency of the requests will be greater than
440            * 10ms; but if only a single request is submitted each 10ms
441            * interval the average latency will be 10ms.
442            *
443            * We need to acquire this mutex to prevent multiple concurrent
444            * threads being assigned to the same lane of a given inject
445            * handler. The mutex allows us to perform the following two
446            * operations atomically:
447            *
448            *        1. determine the minimum handler and minimum target
449            *           value of all the possible handlers
450            *        2. update that minimum handler's lane array
451            *
452            * Without atomicity, two (or more) threads could pick the same
453            * lane in step (1), and then conflict with each other in step
454            * (2). This could allow a single lane handler to process
455            * multiple requests simultaneously, which shouldn't be possible.
456            */
457           mutex_enter(&inject_delay_mtx);
458 
459           for (inject_handler_t *handler = list_head(&inject_handlers);
460               handler != NULL; handler = list_next(&inject_handlers, handler)) {
461                     if (handler->zi_record.zi_cmd != ZINJECT_DELAY_IO)
462                               continue;
463 
464                     if (vd->vdev_guid != handler->zi_record.zi_guid)
465                               continue;
466 
467                     /*
468                      * Defensive; should never happen as the array allocation
469                      * occurs prior to inserting this handler on the list.
470                      */
471                     ASSERT3P(handler->zi_lanes, !=, NULL);
472 
473                     /*
474                      * This should never happen, the zinject command should
475                      * prevent a user from setting an IO delay with zero lanes.
476                      */
477                     ASSERT3U(handler->zi_record.zi_nlanes, !=, 0);
478 
479                     ASSERT3U(handler->zi_record.zi_nlanes, >,
480                         handler->zi_next_lane);
481 
482                     /*
483                      * We want to issue this IO to the lane that will become
484                      * idle the soonest, so we compare the soonest this
485                      * specific handler can complete the IO with all other
486                      * handlers, to find the lowest value of all possible
487                      * lanes. We then use this lane to submit the request.
488                      *
489                      * Since each handler has a constant value for its
490                      * delay, we can just use the "next" lane for that
491                      * handler; as it will always be the lane with the
492                      * lowest value for that particular handler (i.e. the
493                      * lane that will become idle the soonest). This saves a
494                      * scan of each handler's lanes array.
495                      *
496                      * There's two cases to consider when determining when
497                      * this specific IO request should complete. If this
498                      * lane is idle, we want to "submit" the request now so
499                      * it will complete after zi_timer milliseconds. Thus,
500                      * we set the target to now + zi_timer.
501                      *
502                      * If the lane is busy, we want this request to complete
503                      * zi_timer milliseconds after the lane becomes idle.
504                      * Since the 'zi_lanes' array holds the time at which
505                      * each lane will become idle, we use that value to
506                      * determine when this request should complete.
507                      */
508                     hrtime_t idle = handler->zi_record.zi_timer + gethrtime();
509                     hrtime_t busy = handler->zi_record.zi_timer +
510                         handler->zi_lanes[handler->zi_next_lane];
511                     hrtime_t target = MAX(idle, busy);
512 
513                     if (min_handler == NULL) {
514                               min_handler = handler;
515                               min_target = target;
516                               continue;
517                     }
518 
519                     ASSERT3P(min_handler, !=, NULL);
520                     ASSERT3U(min_target, !=, 0);
521 
522                     /*
523                      * We don't yet increment the "next lane" variable since
524                      * we still might find a lower value lane in another
525                      * handler during any remaining iterations. Once we're
526                      * sure we've selected the absolute minimum, we'll claim
527                      * the lane and increment the handler's "next lane"
528                      * field below.
529                      */
530 
531                     if (target < min_target) {
532                               min_handler = handler;
533                               min_target = target;
534                     }
535           }
536 
537           /*
538            * 'min_handler' will be NULL if no IO delays are registered for
539            * this vdev, otherwise it will point to the handler containing
540            * the lane that will become idle the soonest.
541            */
542           if (min_handler != NULL) {
543                     ASSERT3U(min_target, !=, 0);
544                     min_handler->zi_lanes[min_handler->zi_next_lane] = min_target;
545 
546                     /*
547                      * If we've used all possible lanes for this handler,
548                      * loop back and start using the first lane again;
549                      * otherwise, just increment the lane index.
550                      */
551                     min_handler->zi_next_lane = (min_handler->zi_next_lane + 1) %
552                         min_handler->zi_record.zi_nlanes;
553           }
554 
555           mutex_exit(&inject_delay_mtx);
556           rw_exit(&inject_lock);
557 
558           return (min_target);
559 }
560 
561 /*
562  * Create a new handler for the given record.  We add it to the list, adding
563  * a reference to the spa_t in the process.  We increment zio_injection_enabled,
564  * which is the switch to trigger all fault injection.
565  */
566 int
zio_inject_fault(char * name,int flags,int * id,zinject_record_t * record)567 zio_inject_fault(char *name, int flags, int *id, zinject_record_t *record)
568 {
569           inject_handler_t *handler;
570           int error;
571           spa_t *spa;
572 
573           /*
574            * If this is pool-wide metadata, make sure we unload the corresponding
575            * spa_t, so that the next attempt to load it will trigger the fault.
576            * We call spa_reset() to unload the pool appropriately.
577            */
578           if (flags & ZINJECT_UNLOAD_SPA)
579                     if ((error = spa_reset(name)) != 0)
580                               return (error);
581 
582           if (record->zi_cmd == ZINJECT_DELAY_IO) {
583                     /*
584                      * A value of zero for the number of lanes or for the
585                      * delay time doesn't make sense.
586                      */
587                     if (record->zi_timer == 0 || record->zi_nlanes == 0)
588                               return (SET_ERROR(EINVAL));
589 
590                     /*
591                      * The number of lanes is directly mapped to the size of
592                      * an array used by the handler. Thus, to ensure the
593                      * user doesn't trigger an allocation that's "too large"
594                      * we cap the number of lanes here.
595                      */
596                     if (record->zi_nlanes >= UINT16_MAX)
597                               return (SET_ERROR(EINVAL));
598           }
599 
600           if (!(flags & ZINJECT_NULL)) {
601                     /*
602                      * spa_inject_ref() will add an injection reference, which will
603                      * prevent the pool from being removed from the namespace while
604                      * still allowing it to be unloaded.
605                      */
606                     if ((spa = spa_inject_addref(name)) == NULL)
607                               return (SET_ERROR(ENOENT));
608 
609                     handler = kmem_alloc(sizeof (inject_handler_t), KM_SLEEP);
610 
611                     handler->zi_spa = spa;
612                     handler->zi_record = *record;
613 
614                     if (handler->zi_record.zi_cmd == ZINJECT_DELAY_IO) {
615                               handler->zi_lanes = kmem_zalloc(
616                                   sizeof (*handler->zi_lanes) *
617                                   handler->zi_record.zi_nlanes, KM_SLEEP);
618                               handler->zi_next_lane = 0;
619                     } else {
620                               handler->zi_lanes = NULL;
621                               handler->zi_next_lane = 0;
622                     }
623 
624                     rw_enter(&inject_lock, RW_WRITER);
625 
626                     /*
627                      * We can't move this increment into the conditional
628                      * above because we need to hold the RW_WRITER lock of
629                      * inject_lock, and we don't want to hold that while
630                      * allocating the handler's zi_lanes array.
631                      */
632                     if (handler->zi_record.zi_cmd == ZINJECT_DELAY_IO) {
633                               ASSERT3S(inject_delay_count, >=, 0);
634                               inject_delay_count++;
635                               ASSERT3S(inject_delay_count, >, 0);
636                     }
637 
638                     *id = handler->zi_id = inject_next_id++;
639                     list_insert_tail(&inject_handlers, handler);
640                     atomic_inc_32(&zio_injection_enabled);
641 
642                     rw_exit(&inject_lock);
643           }
644 
645           /*
646            * Flush the ARC, so that any attempts to read this data will end up
647            * going to the ZIO layer.  Note that this is a little overkill, but
648            * we don't have the necessary ARC interfaces to do anything else, and
649            * fault injection isn't a performance critical path.
650            */
651           if (flags & ZINJECT_FLUSH_ARC)
652                     /*
653                      * We must use FALSE to ensure arc_flush returns, since
654                      * we're not preventing concurrent ARC insertions.
655                      */
656                     arc_flush(NULL, FALSE);
657 
658           return (0);
659 }
660 
661 /*
662  * Returns the next record with an ID greater than that supplied to the
663  * function.  Used to iterate over all handlers in the system.
664  */
665 int
zio_inject_list_next(int * id,char * name,size_t buflen,zinject_record_t * record)666 zio_inject_list_next(int *id, char *name, size_t buflen,
667     zinject_record_t *record)
668 {
669           inject_handler_t *handler;
670           int ret;
671 
672           mutex_enter(&spa_namespace_lock);
673           rw_enter(&inject_lock, RW_READER);
674 
675           for (handler = list_head(&inject_handlers); handler != NULL;
676               handler = list_next(&inject_handlers, handler))
677                     if (handler->zi_id > *id)
678                               break;
679 
680           if (handler) {
681                     *record = handler->zi_record;
682                     *id = handler->zi_id;
683                     (void) strncpy(name, spa_name(handler->zi_spa), buflen);
684                     ret = 0;
685           } else {
686                     ret = SET_ERROR(ENOENT);
687           }
688 
689           rw_exit(&inject_lock);
690           mutex_exit(&spa_namespace_lock);
691 
692           return (ret);
693 }
694 
695 /*
696  * Clear the fault handler with the given identifier, or return ENOENT if none
697  * exists.
698  */
699 int
zio_clear_fault(int id)700 zio_clear_fault(int id)
701 {
702           inject_handler_t *handler;
703 
704           rw_enter(&inject_lock, RW_WRITER);
705 
706           for (handler = list_head(&inject_handlers); handler != NULL;
707               handler = list_next(&inject_handlers, handler))
708                     if (handler->zi_id == id)
709                               break;
710 
711           if (handler == NULL) {
712                     rw_exit(&inject_lock);
713                     return (SET_ERROR(ENOENT));
714           }
715 
716           if (handler->zi_record.zi_cmd == ZINJECT_DELAY_IO) {
717                     ASSERT3S(inject_delay_count, >, 0);
718                     inject_delay_count--;
719                     ASSERT3S(inject_delay_count, >=, 0);
720           }
721 
722           list_remove(&inject_handlers, handler);
723           rw_exit(&inject_lock);
724 
725           if (handler->zi_record.zi_cmd == ZINJECT_DELAY_IO) {
726                     ASSERT3P(handler->zi_lanes, !=, NULL);
727                     kmem_free(handler->zi_lanes, sizeof (*handler->zi_lanes) *
728                         handler->zi_record.zi_nlanes);
729           } else {
730                     ASSERT3P(handler->zi_lanes, ==, NULL);
731           }
732 
733           spa_inject_delref(handler->zi_spa);
734           kmem_free(handler, sizeof (inject_handler_t));
735           atomic_dec_32(&zio_injection_enabled);
736 
737           return (0);
738 }
739 
740 void
zio_inject_init(void)741 zio_inject_init(void)
742 {
743           rw_init(&inject_lock, NULL, RW_DEFAULT, NULL);
744           mutex_init(&inject_delay_mtx, NULL, MUTEX_DEFAULT, NULL);
745           list_create(&inject_handlers, sizeof (inject_handler_t),
746               offsetof(inject_handler_t, zi_link));
747 }
748 
749 void
zio_inject_fini(void)750 zio_inject_fini(void)
751 {
752           list_destroy(&inject_handlers);
753           mutex_destroy(&inject_delay_mtx);
754           rw_destroy(&inject_lock);
755 }
756