1 | /* $NetBSD: vfs_trans.c,v 1.34 2015/08/24 22:50:32 pooka Exp $ */ |
2 | |
3 | /*- |
4 | * Copyright (c) 2007 The NetBSD Foundation, Inc. |
5 | * All rights reserved. |
6 | * |
7 | * This code is derived from software contributed to The NetBSD Foundation |
8 | * by Juergen Hannken-Illjes. |
9 | * |
10 | * Redistribution and use in source and binary forms, with or without |
11 | * modification, are permitted provided that the following conditions |
12 | * are met: |
13 | * 1. Redistributions of source code must retain the above copyright |
14 | * notice, this list of conditions and the following disclaimer. |
15 | * 2. Redistributions in binary form must reproduce the above copyright |
16 | * notice, this list of conditions and the following disclaimer in the |
17 | * documentation and/or other materials provided with the distribution. |
18 | * |
19 | * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
20 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
21 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
22 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
23 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
24 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
25 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
26 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
27 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
28 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
29 | * POSSIBILITY OF SUCH DAMAGE. |
30 | */ |
31 | |
32 | #include <sys/cdefs.h> |
33 | __KERNEL_RCSID(0, "$NetBSD: vfs_trans.c,v 1.34 2015/08/24 22:50:32 pooka Exp $" ); |
34 | |
35 | /* |
36 | * File system transaction operations. |
37 | */ |
38 | |
39 | #ifdef _KERNEL_OPT |
40 | #include "opt_ddb.h" |
41 | #endif |
42 | |
43 | #include <sys/param.h> |
44 | #include <sys/systm.h> |
45 | #include <sys/atomic.h> |
46 | #include <sys/buf.h> |
47 | #include <sys/kmem.h> |
48 | #include <sys/mount.h> |
49 | #include <sys/pserialize.h> |
50 | #include <sys/vnode.h> |
51 | #define _FSTRANS_API_PRIVATE |
52 | #include <sys/fstrans.h> |
53 | #include <sys/proc.h> |
54 | |
55 | #include <miscfs/specfs/specdev.h> |
56 | |
57 | struct fscow_handler { |
58 | LIST_ENTRY(fscow_handler) ch_list; |
59 | int (*ch_func)(void *, struct buf *, bool); |
60 | void *ch_arg; |
61 | }; |
62 | struct fstrans_lwp_info { |
63 | struct fstrans_lwp_info *fli_succ; |
64 | struct lwp *fli_self; |
65 | struct mount *fli_mount; |
66 | int fli_trans_cnt; |
67 | int fli_cow_cnt; |
68 | enum fstrans_lock_type fli_lock_type; |
69 | LIST_ENTRY(fstrans_lwp_info) fli_list; |
70 | }; |
71 | struct fstrans_mount_info { |
72 | enum fstrans_state fmi_state; |
73 | unsigned int fmi_ref_cnt; |
74 | bool fmi_cow_change; |
75 | LIST_HEAD(, fscow_handler) fmi_cow_handler; |
76 | }; |
77 | |
78 | static specificdata_key_t lwp_data_key; /* Our specific data key. */ |
79 | static kmutex_t vfs_suspend_lock; /* Serialize suspensions. */ |
80 | static kmutex_t fstrans_lock; /* Fstrans big lock. */ |
81 | static kcondvar_t fstrans_state_cv; /* Fstrans or cow state changed. */ |
82 | static kcondvar_t fstrans_count_cv; /* Fstrans or cow count changed. */ |
83 | static pserialize_t fstrans_psz; /* Pserialize state. */ |
84 | static LIST_HEAD(fstrans_lwp_head, fstrans_lwp_info) fstrans_fli_head; |
85 | /* List of all fstrans_lwp_info. */ |
86 | |
87 | static void fstrans_lwp_dtor(void *); |
88 | static void fstrans_mount_dtor(struct mount *); |
89 | static struct fstrans_lwp_info *fstrans_get_lwp_info(struct mount *, bool); |
90 | static bool grant_lock(const enum fstrans_state, const enum fstrans_lock_type); |
91 | static bool state_change_done(const struct mount *); |
92 | static bool cow_state_change_done(const struct mount *); |
93 | static void cow_change_enter(const struct mount *); |
94 | static void cow_change_done(const struct mount *); |
95 | |
96 | /* |
97 | * Initialize. |
98 | */ |
99 | void |
100 | fstrans_init(void) |
101 | { |
102 | int error __diagused; |
103 | |
104 | error = lwp_specific_key_create(&lwp_data_key, fstrans_lwp_dtor); |
105 | KASSERT(error == 0); |
106 | |
107 | mutex_init(&vfs_suspend_lock, MUTEX_DEFAULT, IPL_NONE); |
108 | mutex_init(&fstrans_lock, MUTEX_DEFAULT, IPL_NONE); |
109 | cv_init(&fstrans_state_cv, "fstchg" ); |
110 | cv_init(&fstrans_count_cv, "fstcnt" ); |
111 | fstrans_psz = pserialize_create(); |
112 | LIST_INIT(&fstrans_fli_head); |
113 | } |
114 | |
115 | /* |
116 | * Deallocate lwp state. |
117 | */ |
118 | static void |
119 | fstrans_lwp_dtor(void *arg) |
120 | { |
121 | struct fstrans_lwp_info *fli, *fli_next; |
122 | |
123 | for (fli = arg; fli; fli = fli_next) { |
124 | KASSERT(fli->fli_trans_cnt == 0); |
125 | KASSERT(fli->fli_cow_cnt == 0); |
126 | if (fli->fli_mount != NULL) |
127 | fstrans_mount_dtor(fli->fli_mount); |
128 | fli_next = fli->fli_succ; |
129 | fli->fli_mount = NULL; |
130 | membar_sync(); |
131 | fli->fli_self = NULL; |
132 | } |
133 | } |
134 | |
135 | /* |
136 | * Dereference mount state. |
137 | */ |
138 | static void |
139 | fstrans_mount_dtor(struct mount *mp) |
140 | { |
141 | struct fstrans_mount_info *fmi; |
142 | |
143 | fmi = mp->mnt_transinfo; |
144 | if (atomic_dec_uint_nv(&fmi->fmi_ref_cnt) > 0) |
145 | return; |
146 | |
147 | KASSERT(fmi->fmi_state == FSTRANS_NORMAL); |
148 | KASSERT(LIST_FIRST(&fmi->fmi_cow_handler) == NULL); |
149 | |
150 | kmem_free(fmi, sizeof(*fmi)); |
151 | mp->mnt_iflag &= ~IMNT_HAS_TRANS; |
152 | mp->mnt_transinfo = NULL; |
153 | |
154 | vfs_destroy(mp); |
155 | } |
156 | |
157 | /* |
158 | * Allocate mount state. |
159 | */ |
160 | int |
161 | fstrans_mount(struct mount *mp) |
162 | { |
163 | int error; |
164 | struct fstrans_mount_info *newfmi; |
165 | |
166 | error = vfs_busy(mp, NULL); |
167 | if (error) |
168 | return error; |
169 | newfmi = kmem_alloc(sizeof(*newfmi), KM_SLEEP); |
170 | newfmi->fmi_state = FSTRANS_NORMAL; |
171 | newfmi->fmi_ref_cnt = 1; |
172 | LIST_INIT(&newfmi->fmi_cow_handler); |
173 | newfmi->fmi_cow_change = false; |
174 | |
175 | mp->mnt_transinfo = newfmi; |
176 | mp->mnt_iflag |= IMNT_HAS_TRANS; |
177 | |
178 | vfs_unbusy(mp, true, NULL); |
179 | |
180 | return 0; |
181 | } |
182 | |
183 | /* |
184 | * Deallocate mount state. |
185 | */ |
186 | void |
187 | fstrans_unmount(struct mount *mp) |
188 | { |
189 | |
190 | KASSERT(mp->mnt_transinfo != NULL); |
191 | |
192 | fstrans_mount_dtor(mp); |
193 | } |
194 | |
195 | /* |
196 | * Retrieve the per lwp info for this mount allocating if necessary. |
197 | */ |
198 | static struct fstrans_lwp_info * |
199 | fstrans_get_lwp_info(struct mount *mp, bool do_alloc) |
200 | { |
201 | struct fstrans_lwp_info *fli, *res; |
202 | struct fstrans_mount_info *fmi; |
203 | |
204 | /* |
205 | * Scan our list for a match clearing entries whose mount is gone. |
206 | */ |
207 | res = NULL; |
208 | for (fli = lwp_getspecific(lwp_data_key); fli; fli = fli->fli_succ) { |
209 | if (fli->fli_mount == mp) { |
210 | KASSERT(res == NULL); |
211 | res = fli; |
212 | } else if (fli->fli_mount != NULL && |
213 | (fli->fli_mount->mnt_iflag & IMNT_GONE) != 0 && |
214 | fli->fli_trans_cnt == 0 && fli->fli_cow_cnt == 0) { |
215 | fstrans_mount_dtor(fli->fli_mount); |
216 | fli->fli_mount = NULL; |
217 | } |
218 | } |
219 | if (__predict_true(res != NULL)) |
220 | return res; |
221 | |
222 | if (! do_alloc) |
223 | return NULL; |
224 | |
225 | /* |
226 | * Try to reuse a cleared entry or allocate a new one. |
227 | */ |
228 | for (fli = lwp_getspecific(lwp_data_key); fli; fli = fli->fli_succ) { |
229 | if (fli->fli_mount == NULL) { |
230 | KASSERT(fli->fli_trans_cnt == 0); |
231 | KASSERT(fli->fli_cow_cnt == 0); |
232 | break; |
233 | } |
234 | } |
235 | if (fli == NULL) { |
236 | mutex_enter(&fstrans_lock); |
237 | LIST_FOREACH(fli, &fstrans_fli_head, fli_list) { |
238 | if (fli->fli_self == NULL) { |
239 | KASSERT(fli->fli_trans_cnt == 0); |
240 | KASSERT(fli->fli_cow_cnt == 0); |
241 | fli->fli_self = curlwp; |
242 | fli->fli_succ = lwp_getspecific(lwp_data_key); |
243 | lwp_setspecific(lwp_data_key, fli); |
244 | break; |
245 | } |
246 | } |
247 | mutex_exit(&fstrans_lock); |
248 | } |
249 | if (fli == NULL) { |
250 | fli = kmem_alloc(sizeof(*fli), KM_SLEEP); |
251 | mutex_enter(&fstrans_lock); |
252 | memset(fli, 0, sizeof(*fli)); |
253 | fli->fli_self = curlwp; |
254 | LIST_INSERT_HEAD(&fstrans_fli_head, fli, fli_list); |
255 | mutex_exit(&fstrans_lock); |
256 | fli->fli_succ = lwp_getspecific(lwp_data_key); |
257 | lwp_setspecific(lwp_data_key, fli); |
258 | } |
259 | |
260 | /* |
261 | * Attach the entry to the mount. |
262 | */ |
263 | fmi = mp->mnt_transinfo; |
264 | fli->fli_mount = mp; |
265 | atomic_inc_uint(&fmi->fmi_ref_cnt); |
266 | |
267 | return fli; |
268 | } |
269 | |
270 | /* |
271 | * Check if this lock type is granted at this state. |
272 | */ |
273 | static bool |
274 | grant_lock(const enum fstrans_state state, const enum fstrans_lock_type type) |
275 | { |
276 | |
277 | if (__predict_true(state == FSTRANS_NORMAL)) |
278 | return true; |
279 | if (type == FSTRANS_EXCL) |
280 | return true; |
281 | if (state == FSTRANS_SUSPENDING && type == FSTRANS_LAZY) |
282 | return true; |
283 | |
284 | return false; |
285 | } |
286 | |
287 | /* |
288 | * Start a transaction. If this thread already has a transaction on this |
289 | * file system increment the reference counter. |
290 | */ |
291 | int |
292 | _fstrans_start(struct mount *mp, enum fstrans_lock_type lock_type, int wait) |
293 | { |
294 | int s; |
295 | struct fstrans_lwp_info *fli; |
296 | struct fstrans_mount_info *fmi; |
297 | |
298 | ASSERT_SLEEPABLE(); |
299 | |
300 | if (mp == NULL || (mp->mnt_iflag & IMNT_HAS_TRANS) == 0) |
301 | return 0; |
302 | |
303 | fli = fstrans_get_lwp_info(mp, true); |
304 | |
305 | if (fli->fli_trans_cnt > 0) { |
306 | KASSERT(lock_type != FSTRANS_EXCL); |
307 | fli->fli_trans_cnt += 1; |
308 | |
309 | return 0; |
310 | } |
311 | |
312 | s = pserialize_read_enter(); |
313 | fmi = mp->mnt_transinfo; |
314 | if (__predict_true(grant_lock(fmi->fmi_state, lock_type))) { |
315 | fli->fli_trans_cnt = 1; |
316 | fli->fli_lock_type = lock_type; |
317 | pserialize_read_exit(s); |
318 | |
319 | return 0; |
320 | } |
321 | pserialize_read_exit(s); |
322 | |
323 | if (! wait) |
324 | return EBUSY; |
325 | |
326 | mutex_enter(&fstrans_lock); |
327 | while (! grant_lock(fmi->fmi_state, lock_type)) |
328 | cv_wait(&fstrans_state_cv, &fstrans_lock); |
329 | fli->fli_trans_cnt = 1; |
330 | fli->fli_lock_type = lock_type; |
331 | mutex_exit(&fstrans_lock); |
332 | |
333 | return 0; |
334 | } |
335 | |
336 | /* |
337 | * Finish a transaction. |
338 | */ |
339 | void |
340 | fstrans_done(struct mount *mp) |
341 | { |
342 | int s; |
343 | struct fstrans_lwp_info *fli; |
344 | struct fstrans_mount_info *fmi; |
345 | |
346 | if (mp == NULL || (mp->mnt_iflag & IMNT_HAS_TRANS) == 0) |
347 | return; |
348 | |
349 | fli = fstrans_get_lwp_info(mp, false); |
350 | KASSERT(fli != NULL); |
351 | KASSERT(fli->fli_trans_cnt > 0); |
352 | |
353 | if (fli->fli_trans_cnt > 1) { |
354 | fli->fli_trans_cnt -= 1; |
355 | |
356 | return; |
357 | } |
358 | |
359 | s = pserialize_read_enter(); |
360 | fmi = mp->mnt_transinfo; |
361 | if (__predict_true(fmi->fmi_state == FSTRANS_NORMAL)) { |
362 | fli->fli_trans_cnt = 0; |
363 | pserialize_read_exit(s); |
364 | |
365 | return; |
366 | } |
367 | pserialize_read_exit(s); |
368 | |
369 | mutex_enter(&fstrans_lock); |
370 | fli->fli_trans_cnt = 0; |
371 | cv_signal(&fstrans_count_cv); |
372 | mutex_exit(&fstrans_lock); |
373 | } |
374 | |
375 | /* |
376 | * Check if this thread has an exclusive lock. |
377 | */ |
378 | int |
379 | fstrans_is_owner(struct mount *mp) |
380 | { |
381 | struct fstrans_lwp_info *fli; |
382 | |
383 | if (mp == NULL || (mp->mnt_iflag & IMNT_HAS_TRANS) == 0) |
384 | return 0; |
385 | |
386 | fli = fstrans_get_lwp_info(mp, false); |
387 | if (fli == NULL || fli->fli_trans_cnt == 0) |
388 | return 0; |
389 | |
390 | KASSERT(fli->fli_mount == mp); |
391 | KASSERT(fli->fli_trans_cnt > 0); |
392 | |
393 | return (fli->fli_lock_type == FSTRANS_EXCL); |
394 | } |
395 | |
396 | /* |
397 | * True, if no thread is in a transaction not granted at the current state. |
398 | */ |
399 | static bool |
400 | state_change_done(const struct mount *mp) |
401 | { |
402 | struct fstrans_lwp_info *fli; |
403 | struct fstrans_mount_info *fmi; |
404 | |
405 | KASSERT(mutex_owned(&fstrans_lock)); |
406 | |
407 | fmi = mp->mnt_transinfo; |
408 | LIST_FOREACH(fli, &fstrans_fli_head, fli_list) { |
409 | if (fli->fli_mount != mp) |
410 | continue; |
411 | if (fli->fli_trans_cnt == 0) |
412 | continue; |
413 | if (grant_lock(fmi->fmi_state, fli->fli_lock_type)) |
414 | continue; |
415 | |
416 | return false; |
417 | } |
418 | |
419 | return true; |
420 | } |
421 | |
422 | /* |
423 | * Set new file system state. |
424 | */ |
425 | int |
426 | fstrans_setstate(struct mount *mp, enum fstrans_state new_state) |
427 | { |
428 | int error; |
429 | enum fstrans_state old_state; |
430 | struct fstrans_mount_info *fmi; |
431 | |
432 | fmi = mp->mnt_transinfo; |
433 | old_state = fmi->fmi_state; |
434 | if (old_state == new_state) |
435 | return 0; |
436 | |
437 | mutex_enter(&fstrans_lock); |
438 | fmi->fmi_state = new_state; |
439 | pserialize_perform(fstrans_psz); |
440 | |
441 | /* |
442 | * All threads see the new state now. |
443 | * Wait for transactions invalid at this state to leave. |
444 | */ |
445 | error = 0; |
446 | while (! state_change_done(mp)) { |
447 | error = cv_wait_sig(&fstrans_count_cv, &fstrans_lock); |
448 | if (error) { |
449 | new_state = fmi->fmi_state = FSTRANS_NORMAL; |
450 | break; |
451 | } |
452 | } |
453 | cv_broadcast(&fstrans_state_cv); |
454 | mutex_exit(&fstrans_lock); |
455 | |
456 | if (old_state != new_state) { |
457 | if (old_state == FSTRANS_NORMAL) |
458 | fstrans_start(mp, FSTRANS_EXCL); |
459 | if (new_state == FSTRANS_NORMAL) |
460 | fstrans_done(mp); |
461 | } |
462 | |
463 | return error; |
464 | } |
465 | |
466 | /* |
467 | * Get current file system state. |
468 | */ |
469 | enum fstrans_state |
470 | fstrans_getstate(struct mount *mp) |
471 | { |
472 | struct fstrans_mount_info *fmi; |
473 | |
474 | fmi = mp->mnt_transinfo; |
475 | KASSERT(fmi != NULL); |
476 | |
477 | return fmi->fmi_state; |
478 | } |
479 | |
480 | /* |
481 | * Request a filesystem to suspend all operations. |
482 | */ |
483 | int |
484 | vfs_suspend(struct mount *mp, int nowait) |
485 | { |
486 | int error; |
487 | |
488 | if (nowait) { |
489 | if (!mutex_tryenter(&vfs_suspend_lock)) |
490 | return EWOULDBLOCK; |
491 | } else |
492 | mutex_enter(&vfs_suspend_lock); |
493 | |
494 | mutex_enter(&syncer_mutex); |
495 | if ((error = VFS_SUSPENDCTL(mp, SUSPEND_SUSPEND)) != 0) { |
496 | mutex_exit(&syncer_mutex); |
497 | mutex_exit(&vfs_suspend_lock); |
498 | } |
499 | |
500 | return error; |
501 | } |
502 | |
503 | /* |
504 | * Request a filesystem to resume all operations. |
505 | */ |
506 | void |
507 | vfs_resume(struct mount *mp) |
508 | { |
509 | |
510 | VFS_SUSPENDCTL(mp, SUSPEND_RESUME); |
511 | mutex_exit(&syncer_mutex); |
512 | mutex_exit(&vfs_suspend_lock); |
513 | } |
514 | |
515 | |
516 | /* |
517 | * True, if no thread is running a cow handler. |
518 | */ |
519 | static bool |
520 | cow_state_change_done(const struct mount *mp) |
521 | { |
522 | struct fstrans_lwp_info *fli; |
523 | struct fstrans_mount_info *fmi __diagused; |
524 | |
525 | fmi = mp->mnt_transinfo; |
526 | |
527 | KASSERT(mutex_owned(&fstrans_lock)); |
528 | KASSERT(fmi->fmi_cow_change); |
529 | |
530 | LIST_FOREACH(fli, &fstrans_fli_head, fli_list) { |
531 | if (fli->fli_mount != mp) |
532 | continue; |
533 | if (fli->fli_cow_cnt == 0) |
534 | continue; |
535 | |
536 | return false; |
537 | } |
538 | |
539 | return true; |
540 | } |
541 | |
542 | /* |
543 | * Prepare for changing this mounts cow list. |
544 | * Returns with fstrans_lock locked. |
545 | */ |
546 | static void |
547 | cow_change_enter(const struct mount *mp) |
548 | { |
549 | struct fstrans_mount_info *fmi; |
550 | |
551 | fmi = mp->mnt_transinfo; |
552 | |
553 | mutex_enter(&fstrans_lock); |
554 | |
555 | /* |
556 | * Wait for other threads changing the list. |
557 | */ |
558 | while (fmi->fmi_cow_change) |
559 | cv_wait(&fstrans_state_cv, &fstrans_lock); |
560 | |
561 | /* |
562 | * Wait until all threads are aware of a state change. |
563 | */ |
564 | fmi->fmi_cow_change = true; |
565 | pserialize_perform(fstrans_psz); |
566 | |
567 | while (! cow_state_change_done(mp)) |
568 | cv_wait(&fstrans_count_cv, &fstrans_lock); |
569 | } |
570 | |
571 | /* |
572 | * Done changing this mounts cow list. |
573 | */ |
574 | static void |
575 | cow_change_done(const struct mount *mp) |
576 | { |
577 | struct fstrans_mount_info *fmi; |
578 | |
579 | KASSERT(mutex_owned(&fstrans_lock)); |
580 | |
581 | fmi = mp->mnt_transinfo; |
582 | |
583 | fmi->fmi_cow_change = false; |
584 | pserialize_perform(fstrans_psz); |
585 | |
586 | cv_broadcast(&fstrans_state_cv); |
587 | |
588 | mutex_exit(&fstrans_lock); |
589 | } |
590 | |
591 | /* |
592 | * Add a handler to this mount. |
593 | */ |
594 | int |
595 | fscow_establish(struct mount *mp, int (*func)(void *, struct buf *, bool), |
596 | void *arg) |
597 | { |
598 | struct fstrans_mount_info *fmi; |
599 | struct fscow_handler *newch; |
600 | |
601 | if ((mp->mnt_iflag & IMNT_HAS_TRANS) == 0) |
602 | return EINVAL; |
603 | |
604 | fmi = mp->mnt_transinfo; |
605 | KASSERT(fmi != NULL); |
606 | |
607 | newch = kmem_alloc(sizeof(*newch), KM_SLEEP); |
608 | newch->ch_func = func; |
609 | newch->ch_arg = arg; |
610 | |
611 | cow_change_enter(mp); |
612 | LIST_INSERT_HEAD(&fmi->fmi_cow_handler, newch, ch_list); |
613 | cow_change_done(mp); |
614 | |
615 | return 0; |
616 | } |
617 | |
618 | /* |
619 | * Remove a handler from this mount. |
620 | */ |
621 | int |
622 | fscow_disestablish(struct mount *mp, int (*func)(void *, struct buf *, bool), |
623 | void *arg) |
624 | { |
625 | struct fstrans_mount_info *fmi; |
626 | struct fscow_handler *hp = NULL; |
627 | |
628 | if ((mp->mnt_iflag & IMNT_HAS_TRANS) == 0) |
629 | return EINVAL; |
630 | |
631 | fmi = mp->mnt_transinfo; |
632 | KASSERT(fmi != NULL); |
633 | |
634 | cow_change_enter(mp); |
635 | LIST_FOREACH(hp, &fmi->fmi_cow_handler, ch_list) |
636 | if (hp->ch_func == func && hp->ch_arg == arg) |
637 | break; |
638 | if (hp != NULL) { |
639 | LIST_REMOVE(hp, ch_list); |
640 | kmem_free(hp, sizeof(*hp)); |
641 | } |
642 | cow_change_done(mp); |
643 | |
644 | return hp ? 0 : EINVAL; |
645 | } |
646 | |
647 | /* |
648 | * Check for need to copy block that is about to be written. |
649 | */ |
650 | int |
651 | fscow_run(struct buf *bp, bool data_valid) |
652 | { |
653 | int error, s; |
654 | struct mount *mp; |
655 | struct fstrans_lwp_info *fli; |
656 | struct fstrans_mount_info *fmi; |
657 | struct fscow_handler *hp; |
658 | |
659 | /* |
660 | * First check if we need run the copy-on-write handler. |
661 | */ |
662 | if ((bp->b_flags & B_COWDONE)) |
663 | return 0; |
664 | if (bp->b_vp == NULL) { |
665 | bp->b_flags |= B_COWDONE; |
666 | return 0; |
667 | } |
668 | if (bp->b_vp->v_type == VBLK) |
669 | mp = spec_node_getmountedfs(bp->b_vp); |
670 | else |
671 | mp = bp->b_vp->v_mount; |
672 | if (mp == NULL || (mp->mnt_iflag & IMNT_HAS_TRANS) == 0) { |
673 | bp->b_flags |= B_COWDONE; |
674 | return 0; |
675 | } |
676 | |
677 | fli = fstrans_get_lwp_info(mp, true); |
678 | fmi = mp->mnt_transinfo; |
679 | |
680 | /* |
681 | * On non-recursed run check if other threads |
682 | * want to change the list. |
683 | */ |
684 | if (fli->fli_cow_cnt == 0) { |
685 | s = pserialize_read_enter(); |
686 | if (__predict_false(fmi->fmi_cow_change)) { |
687 | pserialize_read_exit(s); |
688 | mutex_enter(&fstrans_lock); |
689 | while (fmi->fmi_cow_change) |
690 | cv_wait(&fstrans_state_cv, &fstrans_lock); |
691 | fli->fli_cow_cnt = 1; |
692 | mutex_exit(&fstrans_lock); |
693 | } else { |
694 | fli->fli_cow_cnt = 1; |
695 | pserialize_read_exit(s); |
696 | } |
697 | } else |
698 | fli->fli_cow_cnt += 1; |
699 | |
700 | /* |
701 | * Run all copy-on-write handlers, stop on error. |
702 | */ |
703 | error = 0; |
704 | LIST_FOREACH(hp, &fmi->fmi_cow_handler, ch_list) |
705 | if ((error = (*hp->ch_func)(hp->ch_arg, bp, data_valid)) != 0) |
706 | break; |
707 | if (error == 0) |
708 | bp->b_flags |= B_COWDONE; |
709 | |
710 | /* |
711 | * Check if other threads want to change the list. |
712 | */ |
713 | if (fli->fli_cow_cnt > 1) { |
714 | fli->fli_cow_cnt -= 1; |
715 | } else { |
716 | s = pserialize_read_enter(); |
717 | if (__predict_false(fmi->fmi_cow_change)) { |
718 | pserialize_read_exit(s); |
719 | mutex_enter(&fstrans_lock); |
720 | fli->fli_cow_cnt = 0; |
721 | cv_signal(&fstrans_count_cv); |
722 | mutex_exit(&fstrans_lock); |
723 | } else { |
724 | fli->fli_cow_cnt = 0; |
725 | pserialize_read_exit(s); |
726 | } |
727 | } |
728 | |
729 | return error; |
730 | } |
731 | |
732 | #if defined(DDB) |
733 | void fstrans_dump(int); |
734 | |
735 | static void |
736 | fstrans_print_lwp(struct proc *p, struct lwp *l, int verbose) |
737 | { |
738 | char prefix[9]; |
739 | struct fstrans_lwp_info *fli; |
740 | |
741 | snprintf(prefix, sizeof(prefix), "%d.%d" , p->p_pid, l->l_lid); |
742 | LIST_FOREACH(fli, &fstrans_fli_head, fli_list) { |
743 | if (fli->fli_self != l) |
744 | continue; |
745 | if (fli->fli_trans_cnt == 0 && fli->fli_cow_cnt == 0) { |
746 | if (! verbose) |
747 | continue; |
748 | } |
749 | printf("%-8s" , prefix); |
750 | if (verbose) |
751 | printf(" @%p" , fli); |
752 | if (fli->fli_mount != NULL) |
753 | printf(" (%s)" , fli->fli_mount->mnt_stat.f_mntonname); |
754 | else |
755 | printf(" NULL" ); |
756 | if (fli->fli_trans_cnt == 0) { |
757 | printf(" -" ); |
758 | } else { |
759 | switch (fli->fli_lock_type) { |
760 | case FSTRANS_LAZY: |
761 | printf(" lazy" ); |
762 | break; |
763 | case FSTRANS_SHARED: |
764 | printf(" shared" ); |
765 | break; |
766 | case FSTRANS_EXCL: |
767 | printf(" excl" ); |
768 | break; |
769 | default: |
770 | printf(" %#x" , fli->fli_lock_type); |
771 | break; |
772 | } |
773 | } |
774 | printf(" %d cow %d\n" , fli->fli_trans_cnt, fli->fli_cow_cnt); |
775 | prefix[0] = '\0'; |
776 | } |
777 | } |
778 | |
779 | static void |
780 | fstrans_print_mount(struct mount *mp, int verbose) |
781 | { |
782 | struct fstrans_mount_info *fmi; |
783 | |
784 | fmi = mp->mnt_transinfo; |
785 | if (!verbose && (fmi == NULL || fmi->fmi_state == FSTRANS_NORMAL)) |
786 | return; |
787 | |
788 | printf("%-16s " , mp->mnt_stat.f_mntonname); |
789 | if (fmi == NULL) { |
790 | printf("(null)\n" ); |
791 | return; |
792 | } |
793 | switch (fmi->fmi_state) { |
794 | case FSTRANS_NORMAL: |
795 | printf("state normal\n" ); |
796 | break; |
797 | case FSTRANS_SUSPENDING: |
798 | printf("state suspending\n" ); |
799 | break; |
800 | case FSTRANS_SUSPENDED: |
801 | printf("state suspended\n" ); |
802 | break; |
803 | default: |
804 | printf("state %#x\n" , fmi->fmi_state); |
805 | break; |
806 | } |
807 | } |
808 | |
809 | void |
810 | fstrans_dump(int full) |
811 | { |
812 | const struct proclist_desc *pd; |
813 | struct proc *p; |
814 | struct lwp *l; |
815 | struct mount *mp; |
816 | |
817 | printf("Fstrans locks by lwp:\n" ); |
818 | for (pd = proclists; pd->pd_list != NULL; pd++) |
819 | PROCLIST_FOREACH(p, pd->pd_list) |
820 | LIST_FOREACH(l, &p->p_lwps, l_sibling) |
821 | fstrans_print_lwp(p, l, full == 1); |
822 | |
823 | printf("Fstrans state by mount:\n" ); |
824 | TAILQ_FOREACH(mp, &mountlist, mnt_list) |
825 | fstrans_print_mount(mp, full == 1); |
826 | } |
827 | #endif /* defined(DDB) */ |
828 | |