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cae5b340 AX |
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) 2017 by Lawrence Livermore National Security, LLC. | |
23 | */ | |
24 | ||
25 | #include <sys/abd.h> | |
26 | #include <sys/mmp.h> | |
27 | #include <sys/spa.h> | |
28 | #include <sys/spa_impl.h> | |
42f7b73b | 29 | #include <sys/time.h> |
cae5b340 AX |
30 | #include <sys/vdev.h> |
31 | #include <sys/vdev_impl.h> | |
32 | #include <sys/zfs_context.h> | |
33 | #include <sys/callb.h> | |
34 | ||
35 | /* | |
36 | * Multi-Modifier Protection (MMP) attempts to prevent a user from importing | |
37 | * or opening a pool on more than one host at a time. In particular, it | |
38 | * prevents "zpool import -f" on a host from succeeding while the pool is | |
39 | * already imported on another host. There are many other ways in which a | |
40 | * device could be used by two hosts for different purposes at the same time | |
41 | * resulting in pool damage. This implementation does not attempt to detect | |
42 | * those cases. | |
43 | * | |
44 | * MMP operates by ensuring there are frequent visible changes on disk (a | |
45 | * "heartbeat") at all times. And by altering the import process to check | |
46 | * for these changes and failing the import when they are detected. This | |
47 | * functionality is enabled by setting the 'multihost' pool property to on. | |
48 | * | |
49 | * Uberblocks written by the txg_sync thread always go into the first | |
50 | * (N-MMP_BLOCKS_PER_LABEL) slots, the remaining slots are reserved for MMP. | |
51 | * They are used to hold uberblocks which are exactly the same as the last | |
52 | * synced uberblock except that the ub_timestamp is frequently updated. | |
53 | * Like all other uberblocks, the slot is written with an embedded checksum, | |
54 | * and slots with invalid checksums are ignored. This provides the | |
55 | * "heartbeat", with no risk of overwriting good uberblocks that must be | |
56 | * preserved, e.g. previous txgs and associated block pointers. | |
57 | * | |
58 | * Two optional fields are added to uberblock structure: ub_mmp_magic and | |
59 | * ub_mmp_delay. The magic field allows zfs to tell whether ub_mmp_delay is | |
60 | * valid. The delay field is a decaying average of the amount of time between | |
61 | * completion of successive MMP writes, in nanoseconds. It is used to predict | |
62 | * how long the import must wait to detect activity in the pool, before | |
63 | * concluding it is not in use. | |
64 | * | |
65 | * During import an activity test may now be performed to determine if | |
66 | * the pool is in use. The activity test is typically required if the | |
67 | * ZPOOL_CONFIG_HOSTID does not match the system hostid, the pool state is | |
68 | * POOL_STATE_ACTIVE, and the pool is not a root pool. | |
69 | * | |
70 | * The activity test finds the "best" uberblock (highest txg & timestamp), | |
71 | * waits some time, and then finds the "best" uberblock again. If the txg | |
72 | * and timestamp in both "best" uberblocks do not match, the pool is in use | |
73 | * by another host and the import fails. Since the granularity of the | |
74 | * timestamp is in seconds this activity test must take a bare minimum of one | |
75 | * second. In order to assure the accuracy of the activity test, the default | |
76 | * values result in an activity test duration of 10x the mmp write interval. | |
77 | * | |
78 | * The "zpool import" activity test can be expected to take a minimum time of | |
79 | * zfs_multihost_import_intervals * zfs_multihost_interval milliseconds. If the | |
80 | * "best" uberblock has a valid ub_mmp_delay field, then the duration of the | |
81 | * test may take longer if MMP writes were occurring less frequently than | |
82 | * expected. Additionally, the duration is then extended by a random 25% to | |
83 | * attempt to to detect simultaneous imports. For example, if both partner | |
84 | * hosts are rebooted at the same time and automatically attempt to import the | |
85 | * pool. | |
86 | */ | |
87 | ||
88 | /* | |
89 | * Used to control the frequency of mmp writes which are performed when the | |
90 | * 'multihost' pool property is on. This is one factor used to determine the | |
91 | * length of the activity check during import. | |
92 | * | |
93 | * The mmp write period is zfs_multihost_interval / leaf-vdevs milliseconds. | |
94 | * This means that on average an mmp write will be issued for each leaf vdev | |
95 | * every zfs_multihost_interval milliseconds. In practice, the observed period | |
96 | * can vary with the I/O load and this observed value is the delay which is | |
97 | * stored in the uberblock. The minimum allowed value is 100 ms. | |
98 | */ | |
99 | ulong_t zfs_multihost_interval = MMP_DEFAULT_INTERVAL; | |
100 | ||
101 | /* | |
102 | * Used to control the duration of the activity test on import. Smaller values | |
103 | * of zfs_multihost_import_intervals will reduce the import time but increase | |
104 | * the risk of failing to detect an active pool. The total activity check time | |
105 | * is never allowed to drop below one second. A value of 0 is ignored and | |
106 | * treated as if it was set to 1. | |
107 | */ | |
108 | uint_t zfs_multihost_import_intervals = MMP_DEFAULT_IMPORT_INTERVALS; | |
109 | ||
110 | /* | |
111 | * Controls the behavior of the pool when mmp write failures are detected. | |
112 | * | |
113 | * When zfs_multihost_fail_intervals = 0 then mmp write failures are ignored. | |
114 | * The failures will still be reported to the ZED which depending on its | |
115 | * configuration may take action such as suspending the pool or taking a | |
116 | * device offline. | |
117 | * | |
118 | * When zfs_multihost_fail_intervals > 0 then sequential mmp write failures will | |
119 | * cause the pool to be suspended. This occurs when | |
120 | * zfs_multihost_fail_intervals * zfs_multihost_interval milliseconds have | |
121 | * passed since the last successful mmp write. This guarantees the activity | |
122 | * test will see mmp writes if the | |
123 | * pool is imported. | |
124 | */ | |
125 | uint_t zfs_multihost_fail_intervals = MMP_DEFAULT_FAIL_INTERVALS; | |
126 | ||
127 | static void mmp_thread(spa_t *spa); | |
42f7b73b | 128 | char *mmp_tag = "mmp_write_uberblock"; |
cae5b340 AX |
129 | |
130 | void | |
131 | mmp_init(spa_t *spa) | |
132 | { | |
133 | mmp_thread_t *mmp = &spa->spa_mmp; | |
134 | ||
135 | mutex_init(&mmp->mmp_thread_lock, NULL, MUTEX_DEFAULT, NULL); | |
136 | cv_init(&mmp->mmp_thread_cv, NULL, CV_DEFAULT, NULL); | |
137 | mutex_init(&mmp->mmp_io_lock, NULL, MUTEX_DEFAULT, NULL); | |
42f7b73b | 138 | mmp->mmp_kstat_id = 1; |
cae5b340 AX |
139 | } |
140 | ||
141 | void | |
142 | mmp_fini(spa_t *spa) | |
143 | { | |
144 | mmp_thread_t *mmp = &spa->spa_mmp; | |
145 | ||
146 | mutex_destroy(&mmp->mmp_thread_lock); | |
147 | cv_destroy(&mmp->mmp_thread_cv); | |
148 | mutex_destroy(&mmp->mmp_io_lock); | |
149 | } | |
150 | ||
151 | static void | |
152 | mmp_thread_enter(mmp_thread_t *mmp, callb_cpr_t *cpr) | |
153 | { | |
154 | CALLB_CPR_INIT(cpr, &mmp->mmp_thread_lock, callb_generic_cpr, FTAG); | |
155 | mutex_enter(&mmp->mmp_thread_lock); | |
156 | } | |
157 | ||
158 | static void | |
159 | mmp_thread_exit(mmp_thread_t *mmp, kthread_t **mpp, callb_cpr_t *cpr) | |
160 | { | |
161 | ASSERT(*mpp != NULL); | |
162 | *mpp = NULL; | |
163 | cv_broadcast(&mmp->mmp_thread_cv); | |
164 | CALLB_CPR_EXIT(cpr); /* drops &mmp->mmp_thread_lock */ | |
165 | thread_exit(); | |
166 | } | |
167 | ||
168 | void | |
169 | mmp_thread_start(spa_t *spa) | |
170 | { | |
171 | mmp_thread_t *mmp = &spa->spa_mmp; | |
172 | ||
173 | if (spa_writeable(spa)) { | |
174 | mutex_enter(&mmp->mmp_thread_lock); | |
175 | if (!mmp->mmp_thread) { | |
176 | dprintf("mmp_thread_start pool %s\n", | |
177 | spa->spa_name); | |
178 | mmp->mmp_thread = thread_create(NULL, 0, mmp_thread, | |
179 | spa, 0, &p0, TS_RUN, defclsyspri); | |
180 | } | |
181 | mutex_exit(&mmp->mmp_thread_lock); | |
182 | } | |
183 | } | |
184 | ||
185 | void | |
186 | mmp_thread_stop(spa_t *spa) | |
187 | { | |
188 | mmp_thread_t *mmp = &spa->spa_mmp; | |
189 | ||
190 | mutex_enter(&mmp->mmp_thread_lock); | |
191 | mmp->mmp_thread_exiting = 1; | |
192 | cv_broadcast(&mmp->mmp_thread_cv); | |
193 | ||
194 | while (mmp->mmp_thread) { | |
195 | cv_wait(&mmp->mmp_thread_cv, &mmp->mmp_thread_lock); | |
196 | } | |
197 | mutex_exit(&mmp->mmp_thread_lock); | |
198 | ||
199 | ASSERT(mmp->mmp_thread == NULL); | |
200 | mmp->mmp_thread_exiting = 0; | |
201 | } | |
202 | ||
42f7b73b AX |
203 | typedef enum mmp_vdev_state_flag { |
204 | MMP_FAIL_NOT_WRITABLE = (1 << 0), | |
205 | MMP_FAIL_WRITE_PENDING = (1 << 1), | |
206 | } mmp_vdev_state_flag_t; | |
207 | ||
cae5b340 | 208 | static vdev_t * |
42f7b73b | 209 | mmp_random_leaf_impl(vdev_t *vd, int *fail_mask) |
cae5b340 | 210 | { |
41d74433 | 211 | int child_idx; |
cae5b340 | 212 | |
42f7b73b AX |
213 | if (!vdev_writeable(vd)) { |
214 | *fail_mask |= MMP_FAIL_NOT_WRITABLE; | |
cae5b340 | 215 | return (NULL); |
42f7b73b | 216 | } |
cae5b340 | 217 | |
42f7b73b AX |
218 | if (vd->vdev_ops->vdev_op_leaf) { |
219 | vdev_t *ret; | |
220 | ||
221 | if (vd->vdev_mmp_pending != 0) { | |
222 | *fail_mask |= MMP_FAIL_WRITE_PENDING; | |
223 | ret = NULL; | |
224 | } else { | |
225 | ret = vd; | |
226 | } | |
227 | ||
228 | return (ret); | |
229 | } | |
cae5b340 | 230 | |
41d74433 AX |
231 | child_idx = spa_get_random(vd->vdev_children); |
232 | for (int offset = vd->vdev_children; offset > 0; offset--) { | |
233 | vdev_t *leaf; | |
234 | vdev_t *child = vd->vdev_child[(child_idx + offset) % | |
235 | vd->vdev_children]; | |
cae5b340 | 236 | |
42f7b73b | 237 | leaf = mmp_random_leaf_impl(child, fail_mask); |
41d74433 AX |
238 | if (leaf) |
239 | return (leaf); | |
cae5b340 | 240 | } |
41d74433 AX |
241 | |
242 | return (NULL); | |
cae5b340 AX |
243 | } |
244 | ||
42f7b73b AX |
245 | /* |
246 | * Find a leaf vdev to write an MMP block to. It must not have an outstanding | |
247 | * mmp write (if so a new write will also likely block). If there is no usable | |
248 | * leaf in the tree rooted at in_vd, a nonzero error value is returned, and | |
249 | * *out_vd is unchanged. | |
250 | * | |
251 | * The error value returned is a bit field. | |
252 | * | |
253 | * MMP_FAIL_WRITE_PENDING | |
254 | * If set, one or more leaf vdevs are writeable, but have an MMP write which has | |
255 | * not yet completed. | |
256 | * | |
257 | * MMP_FAIL_NOT_WRITABLE | |
258 | * If set, one or more vdevs are not writeable. The children of those vdevs | |
259 | * were not examined. | |
260 | * | |
261 | * Assuming in_vd points to a tree, a random subtree will be chosen to start. | |
262 | * That subtree, and successive ones, will be walked until a usable leaf has | |
263 | * been found, or all subtrees have been examined (except that the children of | |
264 | * un-writeable vdevs are not examined). | |
265 | * | |
266 | * If the leaf vdevs in the tree are healthy, the distribution of returned leaf | |
267 | * vdevs will be even. If there are unhealthy leaves, the following leaves | |
268 | * (child_index % index_children) will be chosen more often. | |
269 | */ | |
270 | ||
271 | static int | |
272 | mmp_random_leaf(vdev_t *in_vd, vdev_t **out_vd) | |
273 | { | |
274 | int error_mask = 0; | |
275 | vdev_t *vd = mmp_random_leaf_impl(in_vd, &error_mask); | |
276 | ||
277 | if (error_mask == 0) | |
278 | *out_vd = vd; | |
279 | ||
280 | return (error_mask); | |
281 | } | |
282 | ||
283 | /* | |
284 | * MMP writes are issued on a fixed schedule, but may complete at variable, | |
285 | * much longer, intervals. The mmp_delay captures long periods between | |
286 | * successful writes for any reason, including disk latency, scheduling delays, | |
287 | * etc. | |
288 | * | |
289 | * The mmp_delay is usually calculated as a decaying average, but if the latest | |
290 | * delay is higher we do not average it, so that we do not hide sudden spikes | |
291 | * which the importing host must wait for. | |
292 | * | |
293 | * If writes are occurring frequently, such as due to a high rate of txg syncs, | |
294 | * the mmp_delay could become very small. Since those short delays depend on | |
295 | * activity we cannot count on, we never allow mmp_delay to get lower than rate | |
296 | * expected if only mmp_thread writes occur. | |
297 | * | |
298 | * If an mmp write was skipped or fails, and we have already waited longer than | |
299 | * mmp_delay, we need to update it so the next write reflects the longer delay. | |
300 | * | |
301 | * Do not set mmp_delay if the multihost property is not on, so as not to | |
302 | * trigger an activity check on import. | |
303 | */ | |
304 | static void | |
305 | mmp_delay_update(spa_t *spa, boolean_t write_completed) | |
306 | { | |
307 | mmp_thread_t *mts = &spa->spa_mmp; | |
308 | hrtime_t delay = gethrtime() - mts->mmp_last_write; | |
309 | ||
310 | ASSERT(MUTEX_HELD(&mts->mmp_io_lock)); | |
311 | ||
312 | if (spa_multihost(spa) == B_FALSE) { | |
313 | mts->mmp_delay = 0; | |
314 | return; | |
315 | } | |
316 | ||
317 | if (delay > mts->mmp_delay) | |
318 | mts->mmp_delay = delay; | |
319 | ||
320 | if (write_completed == B_FALSE) | |
321 | return; | |
322 | ||
323 | mts->mmp_last_write = gethrtime(); | |
324 | ||
325 | /* | |
326 | * strictly less than, in case delay was changed above. | |
327 | */ | |
328 | if (delay < mts->mmp_delay) { | |
329 | hrtime_t min_delay = MSEC2NSEC(zfs_multihost_interval) / | |
330 | vdev_count_leaves(spa); | |
331 | mts->mmp_delay = MAX(((delay + mts->mmp_delay * 127) / 128), | |
332 | min_delay); | |
333 | } | |
334 | } | |
335 | ||
cae5b340 AX |
336 | static void |
337 | mmp_write_done(zio_t *zio) | |
338 | { | |
339 | spa_t *spa = zio->io_spa; | |
340 | vdev_t *vd = zio->io_vd; | |
341 | mmp_thread_t *mts = zio->io_private; | |
342 | ||
343 | mutex_enter(&mts->mmp_io_lock); | |
42f7b73b AX |
344 | uint64_t mmp_kstat_id = vd->vdev_mmp_kstat_id; |
345 | hrtime_t mmp_write_duration = gethrtime() - vd->vdev_mmp_pending; | |
cae5b340 | 346 | |
42f7b73b | 347 | mmp_delay_update(spa, (zio->io_error == 0)); |
cae5b340 | 348 | |
42f7b73b AX |
349 | vd->vdev_mmp_pending = 0; |
350 | vd->vdev_mmp_kstat_id = 0; | |
cae5b340 | 351 | |
cae5b340 | 352 | mutex_exit(&mts->mmp_io_lock); |
42f7b73b AX |
353 | spa_config_exit(spa, SCL_STATE, mmp_tag); |
354 | ||
355 | spa_mmp_history_set(spa, mmp_kstat_id, zio->io_error, | |
356 | mmp_write_duration); | |
cae5b340 AX |
357 | |
358 | abd_free(zio->io_abd); | |
359 | } | |
360 | ||
361 | /* | |
362 | * When the uberblock on-disk is updated by a spa_sync, | |
363 | * creating a new "best" uberblock, update the one stored | |
364 | * in the mmp thread state, used for mmp writes. | |
365 | */ | |
366 | void | |
367 | mmp_update_uberblock(spa_t *spa, uberblock_t *ub) | |
368 | { | |
369 | mmp_thread_t *mmp = &spa->spa_mmp; | |
370 | ||
371 | mutex_enter(&mmp->mmp_io_lock); | |
372 | mmp->mmp_ub = *ub; | |
373 | mmp->mmp_ub.ub_timestamp = gethrestime_sec(); | |
42f7b73b | 374 | mmp_delay_update(spa, B_TRUE); |
cae5b340 AX |
375 | mutex_exit(&mmp->mmp_io_lock); |
376 | } | |
377 | ||
378 | /* | |
379 | * Choose a random vdev, label, and MMP block, and write over it | |
380 | * with a copy of the last-synced uberblock, whose timestamp | |
381 | * has been updated to reflect that the pool is in use. | |
382 | */ | |
383 | static void | |
384 | mmp_write_uberblock(spa_t *spa) | |
385 | { | |
386 | int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL; | |
387 | mmp_thread_t *mmp = &spa->spa_mmp; | |
388 | uberblock_t *ub; | |
42f7b73b AX |
389 | vdev_t *vd = NULL; |
390 | int label, error; | |
cae5b340 AX |
391 | uint64_t offset; |
392 | ||
42f7b73b AX |
393 | hrtime_t lock_acquire_time = gethrtime(); |
394 | spa_config_enter(spa, SCL_STATE, mmp_tag, RW_READER); | |
395 | lock_acquire_time = gethrtime() - lock_acquire_time; | |
396 | if (lock_acquire_time > (MSEC2NSEC(MMP_MIN_INTERVAL) / 10)) | |
397 | zfs_dbgmsg("SCL_STATE acquisition took %llu ns\n", | |
398 | (u_longlong_t)lock_acquire_time); | |
399 | ||
400 | error = mmp_random_leaf(spa->spa_root_vdev, &vd); | |
401 | ||
402 | mutex_enter(&mmp->mmp_io_lock); | |
403 | ||
404 | /* | |
405 | * spa_mmp_history has two types of entries: | |
406 | * Issued MMP write: records time issued, error status, etc. | |
407 | * Skipped MMP write: an MMP write could not be issued because no | |
408 | * suitable leaf vdev was available. See comment above struct | |
409 | * spa_mmp_history for details. | |
410 | */ | |
411 | ||
412 | if (error) { | |
413 | mmp_delay_update(spa, B_FALSE); | |
414 | if (mmp->mmp_skip_error == error) { | |
415 | spa_mmp_history_set_skip(spa, mmp->mmp_kstat_id - 1); | |
416 | } else { | |
417 | mmp->mmp_skip_error = error; | |
418 | spa_mmp_history_add(spa, mmp->mmp_ub.ub_txg, | |
419 | gethrestime_sec(), mmp->mmp_delay, NULL, 0, | |
420 | mmp->mmp_kstat_id++, error); | |
421 | } | |
422 | mutex_exit(&mmp->mmp_io_lock); | |
cae5b340 AX |
423 | spa_config_exit(spa, SCL_STATE, FTAG); |
424 | return; | |
425 | } | |
426 | ||
42f7b73b | 427 | mmp->mmp_skip_error = 0; |
cae5b340 AX |
428 | |
429 | if (mmp->mmp_zio_root == NULL) | |
430 | mmp->mmp_zio_root = zio_root(spa, NULL, NULL, | |
431 | flags | ZIO_FLAG_GODFATHER); | |
432 | ||
433 | ub = &mmp->mmp_ub; | |
434 | ub->ub_timestamp = gethrestime_sec(); | |
435 | ub->ub_mmp_magic = MMP_MAGIC; | |
436 | ub->ub_mmp_delay = mmp->mmp_delay; | |
437 | vd->vdev_mmp_pending = gethrtime(); | |
42f7b73b | 438 | vd->vdev_mmp_kstat_id = mmp->mmp_kstat_id; |
cae5b340 AX |
439 | |
440 | zio_t *zio = zio_null(mmp->mmp_zio_root, spa, NULL, NULL, NULL, flags); | |
441 | abd_t *ub_abd = abd_alloc_for_io(VDEV_UBERBLOCK_SIZE(vd), B_TRUE); | |
442 | abd_zero(ub_abd, VDEV_UBERBLOCK_SIZE(vd)); | |
443 | abd_copy_from_buf(ub_abd, ub, sizeof (uberblock_t)); | |
444 | ||
42f7b73b | 445 | mmp->mmp_kstat_id++; |
cae5b340 AX |
446 | mutex_exit(&mmp->mmp_io_lock); |
447 | ||
448 | offset = VDEV_UBERBLOCK_OFFSET(vd, VDEV_UBERBLOCK_COUNT(vd) - | |
449 | MMP_BLOCKS_PER_LABEL + spa_get_random(MMP_BLOCKS_PER_LABEL)); | |
450 | ||
451 | label = spa_get_random(VDEV_LABELS); | |
452 | vdev_label_write(zio, vd, label, ub_abd, offset, | |
453 | VDEV_UBERBLOCK_SIZE(vd), mmp_write_done, mmp, | |
454 | flags | ZIO_FLAG_DONT_PROPAGATE); | |
455 | ||
42f7b73b AX |
456 | (void) spa_mmp_history_add(spa, ub->ub_txg, ub->ub_timestamp, |
457 | ub->ub_mmp_delay, vd, label, vd->vdev_mmp_kstat_id, 0); | |
cae5b340 AX |
458 | |
459 | zio_nowait(zio); | |
460 | } | |
461 | ||
462 | static void | |
463 | mmp_thread(spa_t *spa) | |
464 | { | |
465 | mmp_thread_t *mmp = &spa->spa_mmp; | |
466 | boolean_t last_spa_suspended = spa_suspended(spa); | |
467 | boolean_t last_spa_multihost = spa_multihost(spa); | |
468 | callb_cpr_t cpr; | |
469 | hrtime_t max_fail_ns = zfs_multihost_fail_intervals * | |
470 | MSEC2NSEC(MAX(zfs_multihost_interval, MMP_MIN_INTERVAL)); | |
471 | ||
472 | mmp_thread_enter(mmp, &cpr); | |
473 | ||
474 | /* | |
475 | * The mmp_write_done() function calculates mmp_delay based on the | |
476 | * prior value of mmp_delay and the elapsed time since the last write. | |
477 | * For the first mmp write, there is no "last write", so we start | |
478 | * with fake, but reasonable, default non-zero values. | |
479 | */ | |
480 | mmp->mmp_delay = MSEC2NSEC(MAX(zfs_multihost_interval, | |
481 | MMP_MIN_INTERVAL)) / MAX(vdev_count_leaves(spa), 1); | |
482 | mmp->mmp_last_write = gethrtime() - mmp->mmp_delay; | |
483 | ||
484 | while (!mmp->mmp_thread_exiting) { | |
485 | uint64_t mmp_fail_intervals = zfs_multihost_fail_intervals; | |
486 | uint64_t mmp_interval = MSEC2NSEC( | |
487 | MAX(zfs_multihost_interval, MMP_MIN_INTERVAL)); | |
488 | boolean_t suspended = spa_suspended(spa); | |
489 | boolean_t multihost = spa_multihost(spa); | |
42f7b73b | 490 | hrtime_t next_time; |
cae5b340 | 491 | |
42f7b73b AX |
492 | if (multihost) |
493 | next_time = gethrtime() + mmp_interval / | |
cae5b340 | 494 | MAX(vdev_count_leaves(spa), 1); |
42f7b73b AX |
495 | else |
496 | next_time = gethrtime() + | |
497 | MSEC2NSEC(MMP_DEFAULT_INTERVAL); | |
cae5b340 AX |
498 | |
499 | /* | |
42f7b73b AX |
500 | * MMP off => on, or suspended => !suspended: |
501 | * No writes occurred recently. Update mmp_last_write to give | |
502 | * us some time to try. | |
cae5b340 AX |
503 | */ |
504 | if ((!last_spa_multihost && multihost) || | |
505 | (last_spa_suspended && !suspended)) { | |
506 | mutex_enter(&mmp->mmp_io_lock); | |
507 | mmp->mmp_last_write = gethrtime(); | |
508 | mutex_exit(&mmp->mmp_io_lock); | |
42f7b73b AX |
509 | } |
510 | ||
511 | /* | |
512 | * MMP on => off: | |
513 | * mmp_delay == 0 tells importing node to skip activity check. | |
514 | */ | |
515 | if (last_spa_multihost && !multihost) { | |
cae5b340 AX |
516 | mutex_enter(&mmp->mmp_io_lock); |
517 | mmp->mmp_delay = 0; | |
518 | mutex_exit(&mmp->mmp_io_lock); | |
519 | } | |
520 | last_spa_multihost = multihost; | |
521 | last_spa_suspended = suspended; | |
522 | ||
523 | /* | |
524 | * Smooth max_fail_ns when its factors are decreased, because | |
525 | * making (max_fail_ns < mmp_interval) results in the pool being | |
526 | * immediately suspended before writes can occur at the new | |
527 | * higher frequency. | |
528 | */ | |
529 | if ((mmp_interval * mmp_fail_intervals) < max_fail_ns) { | |
530 | max_fail_ns = ((31 * max_fail_ns) + (mmp_interval * | |
531 | mmp_fail_intervals)) / 32; | |
532 | } else { | |
533 | max_fail_ns = mmp_interval * mmp_fail_intervals; | |
534 | } | |
535 | ||
536 | /* | |
537 | * Suspend the pool if no MMP write has succeeded in over | |
538 | * mmp_interval * mmp_fail_intervals nanoseconds. | |
539 | */ | |
540 | if (!suspended && mmp_fail_intervals && multihost && | |
42f7b73b AX |
541 | (gethrtime() - mmp->mmp_last_write) > max_fail_ns) { |
542 | cmn_err(CE_WARN, "MMP writes to pool '%s' have not " | |
543 | "succeeded in over %llus; suspending pool", | |
544 | spa_name(spa), | |
545 | NSEC2SEC(gethrtime() - mmp->mmp_last_write)); | |
546 | zio_suspend(spa, NULL, ZIO_SUSPEND_MMP); | |
cae5b340 AX |
547 | } |
548 | ||
42f7b73b | 549 | if (multihost && !suspended) |
cae5b340 AX |
550 | mmp_write_uberblock(spa); |
551 | ||
552 | CALLB_CPR_SAFE_BEGIN(&cpr); | |
42f7b73b AX |
553 | (void) cv_timedwait_sig_hires(&mmp->mmp_thread_cv, |
554 | &mmp->mmp_thread_lock, next_time, USEC2NSEC(1), | |
555 | CALLOUT_FLAG_ABSOLUTE); | |
cae5b340 AX |
556 | CALLB_CPR_SAFE_END(&cpr, &mmp->mmp_thread_lock); |
557 | } | |
558 | ||
559 | /* Outstanding writes are allowed to complete. */ | |
560 | if (mmp->mmp_zio_root) | |
561 | zio_wait(mmp->mmp_zio_root); | |
562 | ||
563 | mmp->mmp_zio_root = NULL; | |
564 | mmp_thread_exit(mmp, &mmp->mmp_thread, &cpr); | |
565 | } | |
566 | ||
567 | /* | |
568 | * Signal the MMP thread to wake it, when it is sleeping on | |
569 | * its cv. Used when some module parameter has changed and | |
570 | * we want the thread to know about it. | |
571 | * Only signal if the pool is active and mmp thread is | |
572 | * running, otherwise there is no thread to wake. | |
573 | */ | |
574 | static void | |
575 | mmp_signal_thread(spa_t *spa) | |
576 | { | |
577 | mmp_thread_t *mmp = &spa->spa_mmp; | |
578 | ||
579 | mutex_enter(&mmp->mmp_thread_lock); | |
580 | if (mmp->mmp_thread) | |
581 | cv_broadcast(&mmp->mmp_thread_cv); | |
582 | mutex_exit(&mmp->mmp_thread_lock); | |
583 | } | |
584 | ||
585 | void | |
586 | mmp_signal_all_threads(void) | |
587 | { | |
588 | spa_t *spa = NULL; | |
589 | ||
590 | mutex_enter(&spa_namespace_lock); | |
591 | while ((spa = spa_next(spa))) { | |
592 | if (spa->spa_state == POOL_STATE_ACTIVE) | |
593 | mmp_signal_thread(spa); | |
594 | } | |
595 | mutex_exit(&spa_namespace_lock); | |
596 | } | |
597 | ||
598 | #if defined(_KERNEL) && defined(HAVE_SPL) | |
599 | #include <linux/mod_compat.h> | |
600 | ||
601 | static int | |
602 | param_set_multihost_interval(const char *val, zfs_kernel_param_t *kp) | |
603 | { | |
604 | int ret; | |
605 | ||
606 | ret = param_set_ulong(val, kp); | |
607 | if (ret < 0) | |
608 | return (ret); | |
609 | ||
610 | mmp_signal_all_threads(); | |
611 | ||
612 | return (ret); | |
613 | } | |
614 | ||
615 | /* BEGIN CSTYLED */ | |
616 | module_param(zfs_multihost_fail_intervals, uint, 0644); | |
617 | MODULE_PARM_DESC(zfs_multihost_fail_intervals, | |
618 | "Max allowed period without a successful mmp write"); | |
619 | ||
620 | module_param_call(zfs_multihost_interval, param_set_multihost_interval, | |
621 | param_get_ulong, &zfs_multihost_interval, 0644); | |
622 | MODULE_PARM_DESC(zfs_multihost_interval, | |
623 | "Milliseconds between mmp writes to each leaf"); | |
624 | ||
625 | module_param(zfs_multihost_import_intervals, uint, 0644); | |
626 | MODULE_PARM_DESC(zfs_multihost_import_intervals, | |
627 | "Number of zfs_multihost_interval periods to wait for activity"); | |
628 | /* END CSTYLED */ | |
629 | #endif |