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36c95590 DH |
1 | /* FS-Cache object state machine handler |
2 | * | |
3 | * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. | |
4 | * Written by David Howells (dhowells@redhat.com) | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | * | |
11 | * See Documentation/filesystems/caching/object.txt for a description of the | |
12 | * object state machine and the in-kernel representations. | |
13 | */ | |
14 | ||
15 | #define FSCACHE_DEBUG_LEVEL COOKIE | |
16 | #include <linux/module.h> | |
440f0aff | 17 | #include <linux/seq_file.h> |
36c95590 DH |
18 | #include "internal.h" |
19 | ||
440f0aff | 20 | const char *fscache_object_states[FSCACHE_OBJECT__NSTATES] = { |
36c95590 DH |
21 | [FSCACHE_OBJECT_INIT] = "OBJECT_INIT", |
22 | [FSCACHE_OBJECT_LOOKING_UP] = "OBJECT_LOOKING_UP", | |
23 | [FSCACHE_OBJECT_CREATING] = "OBJECT_CREATING", | |
24 | [FSCACHE_OBJECT_AVAILABLE] = "OBJECT_AVAILABLE", | |
25 | [FSCACHE_OBJECT_ACTIVE] = "OBJECT_ACTIVE", | |
26 | [FSCACHE_OBJECT_UPDATING] = "OBJECT_UPDATING", | |
27 | [FSCACHE_OBJECT_DYING] = "OBJECT_DYING", | |
28 | [FSCACHE_OBJECT_LC_DYING] = "OBJECT_LC_DYING", | |
29 | [FSCACHE_OBJECT_ABORT_INIT] = "OBJECT_ABORT_INIT", | |
30 | [FSCACHE_OBJECT_RELEASING] = "OBJECT_RELEASING", | |
31 | [FSCACHE_OBJECT_RECYCLING] = "OBJECT_RECYCLING", | |
32 | [FSCACHE_OBJECT_WITHDRAWING] = "OBJECT_WITHDRAWING", | |
33 | [FSCACHE_OBJECT_DEAD] = "OBJECT_DEAD", | |
34 | }; | |
35 | EXPORT_SYMBOL(fscache_object_states); | |
36 | ||
4fbf4291 | 37 | const char fscache_object_states_short[FSCACHE_OBJECT__NSTATES][5] = { |
440f0aff DH |
38 | [FSCACHE_OBJECT_INIT] = "INIT", |
39 | [FSCACHE_OBJECT_LOOKING_UP] = "LOOK", | |
40 | [FSCACHE_OBJECT_CREATING] = "CRTN", | |
41 | [FSCACHE_OBJECT_AVAILABLE] = "AVBL", | |
42 | [FSCACHE_OBJECT_ACTIVE] = "ACTV", | |
43 | [FSCACHE_OBJECT_UPDATING] = "UPDT", | |
44 | [FSCACHE_OBJECT_DYING] = "DYNG", | |
45 | [FSCACHE_OBJECT_LC_DYING] = "LCDY", | |
46 | [FSCACHE_OBJECT_ABORT_INIT] = "ABTI", | |
47 | [FSCACHE_OBJECT_RELEASING] = "RELS", | |
48 | [FSCACHE_OBJECT_RECYCLING] = "RCYC", | |
49 | [FSCACHE_OBJECT_WITHDRAWING] = "WTHD", | |
50 | [FSCACHE_OBJECT_DEAD] = "DEAD", | |
51 | }; | |
52 | ||
36c95590 DH |
53 | static void fscache_object_slow_work_put_ref(struct slow_work *); |
54 | static int fscache_object_slow_work_get_ref(struct slow_work *); | |
55 | static void fscache_object_slow_work_execute(struct slow_work *); | |
440f0aff DH |
56 | #ifdef CONFIG_SLOW_WORK_PROC |
57 | static void fscache_object_slow_work_desc(struct slow_work *, struct seq_file *); | |
58 | #endif | |
36c95590 DH |
59 | static void fscache_initialise_object(struct fscache_object *); |
60 | static void fscache_lookup_object(struct fscache_object *); | |
61 | static void fscache_object_available(struct fscache_object *); | |
62 | static void fscache_release_object(struct fscache_object *); | |
63 | static void fscache_withdraw_object(struct fscache_object *); | |
64 | static void fscache_enqueue_dependents(struct fscache_object *); | |
65 | static void fscache_dequeue_object(struct fscache_object *); | |
66 | ||
67 | const struct slow_work_ops fscache_object_slow_work_ops = { | |
3d7a641e | 68 | .owner = THIS_MODULE, |
36c95590 DH |
69 | .get_ref = fscache_object_slow_work_get_ref, |
70 | .put_ref = fscache_object_slow_work_put_ref, | |
71 | .execute = fscache_object_slow_work_execute, | |
440f0aff DH |
72 | #ifdef CONFIG_SLOW_WORK_PROC |
73 | .desc = fscache_object_slow_work_desc, | |
74 | #endif | |
36c95590 DH |
75 | }; |
76 | EXPORT_SYMBOL(fscache_object_slow_work_ops); | |
77 | ||
78 | /* | |
79 | * we need to notify the parent when an op completes that we had outstanding | |
80 | * upon it | |
81 | */ | |
82 | static inline void fscache_done_parent_op(struct fscache_object *object) | |
83 | { | |
84 | struct fscache_object *parent = object->parent; | |
85 | ||
86 | _enter("OBJ%x {OBJ%x,%x}", | |
87 | object->debug_id, parent->debug_id, parent->n_ops); | |
88 | ||
89 | spin_lock_nested(&parent->lock, 1); | |
90 | parent->n_ops--; | |
91 | parent->n_obj_ops--; | |
92 | if (parent->n_ops == 0) | |
93 | fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED); | |
94 | spin_unlock(&parent->lock); | |
95 | } | |
96 | ||
97 | /* | |
98 | * process events that have been sent to an object's state machine | |
99 | * - initiates parent lookup | |
100 | * - does object lookup | |
101 | * - does object creation | |
102 | * - does object recycling and retirement | |
103 | * - does object withdrawal | |
104 | */ | |
105 | static void fscache_object_state_machine(struct fscache_object *object) | |
106 | { | |
107 | enum fscache_object_state new_state; | |
d461d26d | 108 | struct fscache_cookie *cookie; |
36c95590 DH |
109 | |
110 | ASSERT(object != NULL); | |
111 | ||
112 | _enter("{OBJ%x,%s,%lx}", | |
113 | object->debug_id, fscache_object_states[object->state], | |
114 | object->events); | |
115 | ||
116 | switch (object->state) { | |
117 | /* wait for the parent object to become ready */ | |
118 | case FSCACHE_OBJECT_INIT: | |
119 | object->event_mask = | |
120 | ULONG_MAX & ~(1 << FSCACHE_OBJECT_EV_CLEARED); | |
121 | fscache_initialise_object(object); | |
122 | goto done; | |
123 | ||
124 | /* look up the object metadata on disk */ | |
125 | case FSCACHE_OBJECT_LOOKING_UP: | |
126 | fscache_lookup_object(object); | |
127 | goto lookup_transit; | |
128 | ||
129 | /* create the object metadata on disk */ | |
130 | case FSCACHE_OBJECT_CREATING: | |
131 | fscache_lookup_object(object); | |
132 | goto lookup_transit; | |
133 | ||
134 | /* handle an object becoming available; start pending | |
135 | * operations and queue dependent operations for processing */ | |
136 | case FSCACHE_OBJECT_AVAILABLE: | |
137 | fscache_object_available(object); | |
138 | goto active_transit; | |
139 | ||
140 | /* normal running state */ | |
141 | case FSCACHE_OBJECT_ACTIVE: | |
142 | goto active_transit; | |
143 | ||
144 | /* update the object metadata on disk */ | |
145 | case FSCACHE_OBJECT_UPDATING: | |
146 | clear_bit(FSCACHE_OBJECT_EV_UPDATE, &object->events); | |
147 | fscache_stat(&fscache_n_updates_run); | |
52bd75fd | 148 | fscache_stat(&fscache_n_cop_update_object); |
36c95590 | 149 | object->cache->ops->update_object(object); |
52bd75fd | 150 | fscache_stat_d(&fscache_n_cop_update_object); |
36c95590 DH |
151 | goto active_transit; |
152 | ||
153 | /* handle an object dying during lookup or creation */ | |
154 | case FSCACHE_OBJECT_LC_DYING: | |
155 | object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE); | |
52bd75fd | 156 | fscache_stat(&fscache_n_cop_lookup_complete); |
36c95590 | 157 | object->cache->ops->lookup_complete(object); |
52bd75fd | 158 | fscache_stat_d(&fscache_n_cop_lookup_complete); |
36c95590 DH |
159 | |
160 | spin_lock(&object->lock); | |
161 | object->state = FSCACHE_OBJECT_DYING; | |
d461d26d DH |
162 | cookie = object->cookie; |
163 | if (cookie) { | |
164 | if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP, | |
165 | &cookie->flags)) | |
166 | wake_up_bit(&cookie->flags, | |
167 | FSCACHE_COOKIE_LOOKING_UP); | |
168 | if (test_and_clear_bit(FSCACHE_COOKIE_CREATING, | |
169 | &cookie->flags)) | |
170 | wake_up_bit(&cookie->flags, | |
171 | FSCACHE_COOKIE_CREATING); | |
172 | } | |
36c95590 DH |
173 | spin_unlock(&object->lock); |
174 | ||
175 | fscache_done_parent_op(object); | |
176 | ||
177 | /* wait for completion of all active operations on this object | |
178 | * and the death of all child objects of this object */ | |
179 | case FSCACHE_OBJECT_DYING: | |
180 | dying: | |
181 | clear_bit(FSCACHE_OBJECT_EV_CLEARED, &object->events); | |
182 | spin_lock(&object->lock); | |
183 | _debug("dying OBJ%x {%d,%d}", | |
184 | object->debug_id, object->n_ops, object->n_children); | |
185 | if (object->n_ops == 0 && object->n_children == 0) { | |
186 | object->event_mask &= | |
187 | ~(1 << FSCACHE_OBJECT_EV_CLEARED); | |
188 | object->event_mask |= | |
189 | (1 << FSCACHE_OBJECT_EV_WITHDRAW) | | |
190 | (1 << FSCACHE_OBJECT_EV_RETIRE) | | |
191 | (1 << FSCACHE_OBJECT_EV_RELEASE) | | |
192 | (1 << FSCACHE_OBJECT_EV_ERROR); | |
193 | } else { | |
194 | object->event_mask &= | |
195 | ~((1 << FSCACHE_OBJECT_EV_WITHDRAW) | | |
196 | (1 << FSCACHE_OBJECT_EV_RETIRE) | | |
197 | (1 << FSCACHE_OBJECT_EV_RELEASE) | | |
198 | (1 << FSCACHE_OBJECT_EV_ERROR)); | |
199 | object->event_mask |= | |
200 | 1 << FSCACHE_OBJECT_EV_CLEARED; | |
201 | } | |
202 | spin_unlock(&object->lock); | |
203 | fscache_enqueue_dependents(object); | |
60d543ca | 204 | fscache_start_operations(object); |
36c95590 DH |
205 | goto terminal_transit; |
206 | ||
207 | /* handle an abort during initialisation */ | |
208 | case FSCACHE_OBJECT_ABORT_INIT: | |
209 | _debug("handle abort init %lx", object->events); | |
210 | object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE); | |
211 | ||
212 | spin_lock(&object->lock); | |
213 | fscache_dequeue_object(object); | |
214 | ||
215 | object->state = FSCACHE_OBJECT_DYING; | |
216 | if (test_and_clear_bit(FSCACHE_COOKIE_CREATING, | |
217 | &object->cookie->flags)) | |
218 | wake_up_bit(&object->cookie->flags, | |
219 | FSCACHE_COOKIE_CREATING); | |
220 | spin_unlock(&object->lock); | |
221 | goto dying; | |
222 | ||
223 | /* handle the netfs releasing an object and possibly marking it | |
224 | * obsolete too */ | |
225 | case FSCACHE_OBJECT_RELEASING: | |
226 | case FSCACHE_OBJECT_RECYCLING: | |
227 | object->event_mask &= | |
228 | ~((1 << FSCACHE_OBJECT_EV_WITHDRAW) | | |
229 | (1 << FSCACHE_OBJECT_EV_RETIRE) | | |
230 | (1 << FSCACHE_OBJECT_EV_RELEASE) | | |
231 | (1 << FSCACHE_OBJECT_EV_ERROR)); | |
232 | fscache_release_object(object); | |
233 | spin_lock(&object->lock); | |
234 | object->state = FSCACHE_OBJECT_DEAD; | |
235 | spin_unlock(&object->lock); | |
236 | fscache_stat(&fscache_n_object_dead); | |
237 | goto terminal_transit; | |
238 | ||
239 | /* handle the parent cache of this object being withdrawn from | |
240 | * active service */ | |
241 | case FSCACHE_OBJECT_WITHDRAWING: | |
242 | object->event_mask &= | |
243 | ~((1 << FSCACHE_OBJECT_EV_WITHDRAW) | | |
244 | (1 << FSCACHE_OBJECT_EV_RETIRE) | | |
245 | (1 << FSCACHE_OBJECT_EV_RELEASE) | | |
246 | (1 << FSCACHE_OBJECT_EV_ERROR)); | |
247 | fscache_withdraw_object(object); | |
248 | spin_lock(&object->lock); | |
249 | object->state = FSCACHE_OBJECT_DEAD; | |
250 | spin_unlock(&object->lock); | |
251 | fscache_stat(&fscache_n_object_dead); | |
252 | goto terminal_transit; | |
253 | ||
254 | /* complain about the object being woken up once it is | |
255 | * deceased */ | |
256 | case FSCACHE_OBJECT_DEAD: | |
257 | printk(KERN_ERR "FS-Cache:" | |
258 | " Unexpected event in dead state %lx\n", | |
259 | object->events & object->event_mask); | |
260 | BUG(); | |
261 | ||
262 | default: | |
263 | printk(KERN_ERR "FS-Cache: Unknown object state %u\n", | |
264 | object->state); | |
265 | BUG(); | |
266 | } | |
267 | ||
268 | /* determine the transition from a lookup state */ | |
269 | lookup_transit: | |
270 | switch (fls(object->events & object->event_mask) - 1) { | |
271 | case FSCACHE_OBJECT_EV_WITHDRAW: | |
272 | case FSCACHE_OBJECT_EV_RETIRE: | |
273 | case FSCACHE_OBJECT_EV_RELEASE: | |
274 | case FSCACHE_OBJECT_EV_ERROR: | |
275 | new_state = FSCACHE_OBJECT_LC_DYING; | |
276 | goto change_state; | |
277 | case FSCACHE_OBJECT_EV_REQUEUE: | |
278 | goto done; | |
279 | case -1: | |
280 | goto done; /* sleep until event */ | |
281 | default: | |
282 | goto unsupported_event; | |
283 | } | |
284 | ||
285 | /* determine the transition from an active state */ | |
286 | active_transit: | |
287 | switch (fls(object->events & object->event_mask) - 1) { | |
288 | case FSCACHE_OBJECT_EV_WITHDRAW: | |
289 | case FSCACHE_OBJECT_EV_RETIRE: | |
290 | case FSCACHE_OBJECT_EV_RELEASE: | |
291 | case FSCACHE_OBJECT_EV_ERROR: | |
292 | new_state = FSCACHE_OBJECT_DYING; | |
293 | goto change_state; | |
294 | case FSCACHE_OBJECT_EV_UPDATE: | |
295 | new_state = FSCACHE_OBJECT_UPDATING; | |
296 | goto change_state; | |
297 | case -1: | |
298 | new_state = FSCACHE_OBJECT_ACTIVE; | |
299 | goto change_state; /* sleep until event */ | |
300 | default: | |
301 | goto unsupported_event; | |
302 | } | |
303 | ||
304 | /* determine the transition from a terminal state */ | |
305 | terminal_transit: | |
306 | switch (fls(object->events & object->event_mask) - 1) { | |
307 | case FSCACHE_OBJECT_EV_WITHDRAW: | |
308 | new_state = FSCACHE_OBJECT_WITHDRAWING; | |
309 | goto change_state; | |
310 | case FSCACHE_OBJECT_EV_RETIRE: | |
311 | new_state = FSCACHE_OBJECT_RECYCLING; | |
312 | goto change_state; | |
313 | case FSCACHE_OBJECT_EV_RELEASE: | |
314 | new_state = FSCACHE_OBJECT_RELEASING; | |
315 | goto change_state; | |
316 | case FSCACHE_OBJECT_EV_ERROR: | |
317 | new_state = FSCACHE_OBJECT_WITHDRAWING; | |
318 | goto change_state; | |
319 | case FSCACHE_OBJECT_EV_CLEARED: | |
320 | new_state = FSCACHE_OBJECT_DYING; | |
321 | goto change_state; | |
322 | case -1: | |
323 | goto done; /* sleep until event */ | |
324 | default: | |
325 | goto unsupported_event; | |
326 | } | |
327 | ||
328 | change_state: | |
329 | spin_lock(&object->lock); | |
330 | object->state = new_state; | |
331 | spin_unlock(&object->lock); | |
332 | ||
333 | done: | |
334 | _leave(" [->%s]", fscache_object_states[object->state]); | |
335 | return; | |
336 | ||
337 | unsupported_event: | |
338 | printk(KERN_ERR "FS-Cache:" | |
339 | " Unsupported event %lx [mask %lx] in state %s\n", | |
340 | object->events, object->event_mask, | |
341 | fscache_object_states[object->state]); | |
342 | BUG(); | |
343 | } | |
344 | ||
345 | /* | |
346 | * execute an object | |
347 | */ | |
348 | static void fscache_object_slow_work_execute(struct slow_work *work) | |
349 | { | |
350 | struct fscache_object *object = | |
351 | container_of(work, struct fscache_object, work); | |
352 | unsigned long start; | |
353 | ||
354 | _enter("{OBJ%x}", object->debug_id); | |
355 | ||
36c95590 DH |
356 | start = jiffies; |
357 | fscache_object_state_machine(object); | |
358 | fscache_hist(fscache_objs_histogram, start); | |
359 | if (object->events & object->event_mask) | |
360 | fscache_enqueue_object(object); | |
868411be | 361 | clear_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events); |
36c95590 DH |
362 | } |
363 | ||
440f0aff DH |
364 | /* |
365 | * describe an object for slow-work debugging | |
366 | */ | |
367 | #ifdef CONFIG_SLOW_WORK_PROC | |
368 | static void fscache_object_slow_work_desc(struct slow_work *work, | |
369 | struct seq_file *m) | |
370 | { | |
371 | struct fscache_object *object = | |
372 | container_of(work, struct fscache_object, work); | |
373 | ||
374 | seq_printf(m, "FSC: OBJ%x: %s", | |
375 | object->debug_id, | |
376 | fscache_object_states_short[object->state]); | |
377 | } | |
378 | #endif | |
379 | ||
36c95590 DH |
380 | /* |
381 | * initialise an object | |
382 | * - check the specified object's parent to see if we can make use of it | |
383 | * immediately to do a creation | |
384 | * - we may need to start the process of creating a parent and we need to wait | |
385 | * for the parent's lookup and creation to complete if it's not there yet | |
386 | * - an object's cookie is pinned until we clear FSCACHE_COOKIE_CREATING on the | |
387 | * leaf-most cookies of the object and all its children | |
388 | */ | |
389 | static void fscache_initialise_object(struct fscache_object *object) | |
390 | { | |
391 | struct fscache_object *parent; | |
392 | ||
393 | _enter(""); | |
394 | ASSERT(object->cookie != NULL); | |
395 | ASSERT(object->cookie->parent != NULL); | |
396 | ASSERT(list_empty(&object->work.link)); | |
397 | ||
398 | if (object->events & ((1 << FSCACHE_OBJECT_EV_ERROR) | | |
399 | (1 << FSCACHE_OBJECT_EV_RELEASE) | | |
400 | (1 << FSCACHE_OBJECT_EV_RETIRE) | | |
401 | (1 << FSCACHE_OBJECT_EV_WITHDRAW))) { | |
402 | _debug("abort init %lx", object->events); | |
403 | spin_lock(&object->lock); | |
404 | object->state = FSCACHE_OBJECT_ABORT_INIT; | |
405 | spin_unlock(&object->lock); | |
406 | return; | |
407 | } | |
408 | ||
409 | spin_lock(&object->cookie->lock); | |
410 | spin_lock_nested(&object->cookie->parent->lock, 1); | |
411 | ||
412 | parent = object->parent; | |
413 | if (!parent) { | |
414 | _debug("no parent"); | |
415 | set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events); | |
416 | } else { | |
417 | spin_lock(&object->lock); | |
418 | spin_lock_nested(&parent->lock, 1); | |
419 | _debug("parent %s", fscache_object_states[parent->state]); | |
420 | ||
421 | if (parent->state >= FSCACHE_OBJECT_DYING) { | |
422 | _debug("bad parent"); | |
423 | set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events); | |
424 | } else if (parent->state < FSCACHE_OBJECT_AVAILABLE) { | |
425 | _debug("wait"); | |
426 | ||
427 | /* we may get woken up in this state by child objects | |
428 | * binding on to us, so we need to make sure we don't | |
429 | * add ourself to the list multiple times */ | |
430 | if (list_empty(&object->dep_link)) { | |
52bd75fd | 431 | fscache_stat(&fscache_n_cop_grab_object); |
36c95590 | 432 | object->cache->ops->grab_object(object); |
52bd75fd | 433 | fscache_stat_d(&fscache_n_cop_grab_object); |
36c95590 DH |
434 | list_add(&object->dep_link, |
435 | &parent->dependents); | |
436 | ||
437 | /* fscache_acquire_non_index_cookie() uses this | |
438 | * to wake the chain up */ | |
439 | if (parent->state == FSCACHE_OBJECT_INIT) | |
440 | fscache_enqueue_object(parent); | |
441 | } | |
442 | } else { | |
443 | _debug("go"); | |
444 | parent->n_ops++; | |
445 | parent->n_obj_ops++; | |
446 | object->lookup_jif = jiffies; | |
447 | object->state = FSCACHE_OBJECT_LOOKING_UP; | |
448 | set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events); | |
449 | } | |
450 | ||
451 | spin_unlock(&parent->lock); | |
452 | spin_unlock(&object->lock); | |
453 | } | |
454 | ||
455 | spin_unlock(&object->cookie->parent->lock); | |
456 | spin_unlock(&object->cookie->lock); | |
457 | _leave(""); | |
458 | } | |
459 | ||
460 | /* | |
461 | * look an object up in the cache from which it was allocated | |
462 | * - we hold an "access lock" on the parent object, so the parent object cannot | |
463 | * be withdrawn by either party till we've finished | |
464 | * - an object's cookie is pinned until we clear FSCACHE_COOKIE_CREATING on the | |
465 | * leaf-most cookies of the object and all its children | |
466 | */ | |
467 | static void fscache_lookup_object(struct fscache_object *object) | |
468 | { | |
469 | struct fscache_cookie *cookie = object->cookie; | |
470 | struct fscache_object *parent; | |
471 | ||
472 | _enter(""); | |
473 | ||
474 | parent = object->parent; | |
475 | ASSERT(parent != NULL); | |
476 | ASSERTCMP(parent->n_ops, >, 0); | |
477 | ASSERTCMP(parent->n_obj_ops, >, 0); | |
478 | ||
479 | /* make sure the parent is still available */ | |
480 | ASSERTCMP(parent->state, >=, FSCACHE_OBJECT_AVAILABLE); | |
481 | ||
482 | if (parent->state >= FSCACHE_OBJECT_DYING || | |
483 | test_bit(FSCACHE_IOERROR, &object->cache->flags)) { | |
484 | _debug("unavailable"); | |
485 | set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events); | |
486 | _leave(""); | |
487 | return; | |
488 | } | |
489 | ||
490 | _debug("LOOKUP \"%s/%s\" in \"%s\"", | |
491 | parent->cookie->def->name, cookie->def->name, | |
492 | object->cache->tag->name); | |
493 | ||
494 | fscache_stat(&fscache_n_object_lookups); | |
52bd75fd | 495 | fscache_stat(&fscache_n_cop_lookup_object); |
36c95590 | 496 | object->cache->ops->lookup_object(object); |
52bd75fd | 497 | fscache_stat_d(&fscache_n_cop_lookup_object); |
36c95590 DH |
498 | |
499 | if (test_bit(FSCACHE_OBJECT_EV_ERROR, &object->events)) | |
500 | set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags); | |
501 | ||
502 | _leave(""); | |
503 | } | |
504 | ||
505 | /** | |
506 | * fscache_object_lookup_negative - Note negative cookie lookup | |
507 | * @object: Object pointing to cookie to mark | |
508 | * | |
509 | * Note negative lookup, permitting those waiting to read data from an already | |
510 | * existing backing object to continue as there's no data for them to read. | |
511 | */ | |
512 | void fscache_object_lookup_negative(struct fscache_object *object) | |
513 | { | |
514 | struct fscache_cookie *cookie = object->cookie; | |
515 | ||
516 | _enter("{OBJ%x,%s}", | |
517 | object->debug_id, fscache_object_states[object->state]); | |
518 | ||
519 | spin_lock(&object->lock); | |
520 | if (object->state == FSCACHE_OBJECT_LOOKING_UP) { | |
521 | fscache_stat(&fscache_n_object_lookups_negative); | |
522 | ||
523 | /* transit here to allow write requests to begin stacking up | |
524 | * and read requests to begin returning ENODATA */ | |
525 | object->state = FSCACHE_OBJECT_CREATING; | |
526 | spin_unlock(&object->lock); | |
527 | ||
528 | set_bit(FSCACHE_COOKIE_PENDING_FILL, &cookie->flags); | |
529 | set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags); | |
530 | ||
531 | _debug("wake up lookup %p", &cookie->flags); | |
532 | smp_mb__before_clear_bit(); | |
533 | clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags); | |
534 | smp_mb__after_clear_bit(); | |
535 | wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP); | |
536 | set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events); | |
537 | } else { | |
538 | ASSERTCMP(object->state, ==, FSCACHE_OBJECT_CREATING); | |
539 | spin_unlock(&object->lock); | |
540 | } | |
541 | ||
542 | _leave(""); | |
543 | } | |
544 | EXPORT_SYMBOL(fscache_object_lookup_negative); | |
545 | ||
546 | /** | |
547 | * fscache_obtained_object - Note successful object lookup or creation | |
548 | * @object: Object pointing to cookie to mark | |
549 | * | |
550 | * Note successful lookup and/or creation, permitting those waiting to write | |
551 | * data to a backing object to continue. | |
552 | * | |
553 | * Note that after calling this, an object's cookie may be relinquished by the | |
554 | * netfs, and so must be accessed with object lock held. | |
555 | */ | |
556 | void fscache_obtained_object(struct fscache_object *object) | |
557 | { | |
558 | struct fscache_cookie *cookie = object->cookie; | |
559 | ||
560 | _enter("{OBJ%x,%s}", | |
561 | object->debug_id, fscache_object_states[object->state]); | |
562 | ||
563 | /* if we were still looking up, then we must have a positive lookup | |
564 | * result, in which case there may be data available */ | |
565 | spin_lock(&object->lock); | |
566 | if (object->state == FSCACHE_OBJECT_LOOKING_UP) { | |
567 | fscache_stat(&fscache_n_object_lookups_positive); | |
568 | ||
569 | clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags); | |
570 | ||
571 | object->state = FSCACHE_OBJECT_AVAILABLE; | |
572 | spin_unlock(&object->lock); | |
573 | ||
574 | smp_mb__before_clear_bit(); | |
575 | clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags); | |
576 | smp_mb__after_clear_bit(); | |
577 | wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP); | |
578 | set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events); | |
579 | } else { | |
580 | ASSERTCMP(object->state, ==, FSCACHE_OBJECT_CREATING); | |
581 | fscache_stat(&fscache_n_object_created); | |
582 | ||
583 | object->state = FSCACHE_OBJECT_AVAILABLE; | |
584 | spin_unlock(&object->lock); | |
585 | set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events); | |
586 | smp_wmb(); | |
587 | } | |
588 | ||
589 | if (test_and_clear_bit(FSCACHE_COOKIE_CREATING, &cookie->flags)) | |
590 | wake_up_bit(&cookie->flags, FSCACHE_COOKIE_CREATING); | |
591 | ||
592 | _leave(""); | |
593 | } | |
594 | EXPORT_SYMBOL(fscache_obtained_object); | |
595 | ||
596 | /* | |
597 | * handle an object that has just become available | |
598 | */ | |
599 | static void fscache_object_available(struct fscache_object *object) | |
600 | { | |
601 | _enter("{OBJ%x}", object->debug_id); | |
602 | ||
603 | spin_lock(&object->lock); | |
604 | ||
6897e3df DH |
605 | if (object->cookie && |
606 | test_and_clear_bit(FSCACHE_COOKIE_CREATING, &object->cookie->flags)) | |
36c95590 DH |
607 | wake_up_bit(&object->cookie->flags, FSCACHE_COOKIE_CREATING); |
608 | ||
609 | fscache_done_parent_op(object); | |
610 | if (object->n_in_progress == 0) { | |
611 | if (object->n_ops > 0) { | |
612 | ASSERTCMP(object->n_ops, >=, object->n_obj_ops); | |
613 | ASSERTIF(object->n_ops > object->n_obj_ops, | |
614 | !list_empty(&object->pending_ops)); | |
615 | fscache_start_operations(object); | |
616 | } else { | |
617 | ASSERT(list_empty(&object->pending_ops)); | |
618 | } | |
619 | } | |
620 | spin_unlock(&object->lock); | |
621 | ||
52bd75fd | 622 | fscache_stat(&fscache_n_cop_lookup_complete); |
36c95590 | 623 | object->cache->ops->lookup_complete(object); |
52bd75fd | 624 | fscache_stat_d(&fscache_n_cop_lookup_complete); |
36c95590 DH |
625 | fscache_enqueue_dependents(object); |
626 | ||
627 | fscache_hist(fscache_obj_instantiate_histogram, object->lookup_jif); | |
628 | fscache_stat(&fscache_n_object_avail); | |
629 | ||
630 | _leave(""); | |
631 | } | |
632 | ||
633 | /* | |
634 | * drop an object's attachments | |
635 | */ | |
636 | static void fscache_drop_object(struct fscache_object *object) | |
637 | { | |
638 | struct fscache_object *parent = object->parent; | |
639 | struct fscache_cache *cache = object->cache; | |
640 | ||
641 | _enter("{OBJ%x,%d}", object->debug_id, object->n_children); | |
642 | ||
6897e3df DH |
643 | ASSERTCMP(object->cookie, ==, NULL); |
644 | ASSERT(hlist_unhashed(&object->cookie_link)); | |
645 | ||
36c95590 DH |
646 | spin_lock(&cache->object_list_lock); |
647 | list_del_init(&object->cache_link); | |
648 | spin_unlock(&cache->object_list_lock); | |
649 | ||
52bd75fd | 650 | fscache_stat(&fscache_n_cop_drop_object); |
36c95590 | 651 | cache->ops->drop_object(object); |
52bd75fd | 652 | fscache_stat_d(&fscache_n_cop_drop_object); |
36c95590 DH |
653 | |
654 | if (parent) { | |
655 | _debug("release parent OBJ%x {%d}", | |
656 | parent->debug_id, parent->n_children); | |
657 | ||
658 | spin_lock(&parent->lock); | |
659 | parent->n_children--; | |
660 | if (parent->n_children == 0) | |
661 | fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED); | |
662 | spin_unlock(&parent->lock); | |
663 | object->parent = NULL; | |
664 | } | |
665 | ||
666 | /* this just shifts the object release to the slow work processor */ | |
52bd75fd | 667 | fscache_stat(&fscache_n_cop_put_object); |
36c95590 | 668 | object->cache->ops->put_object(object); |
52bd75fd | 669 | fscache_stat_d(&fscache_n_cop_put_object); |
36c95590 DH |
670 | |
671 | _leave(""); | |
672 | } | |
673 | ||
674 | /* | |
675 | * release or recycle an object that the netfs has discarded | |
676 | */ | |
677 | static void fscache_release_object(struct fscache_object *object) | |
678 | { | |
679 | _enter(""); | |
680 | ||
681 | fscache_drop_object(object); | |
682 | } | |
683 | ||
684 | /* | |
685 | * withdraw an object from active service | |
686 | */ | |
687 | static void fscache_withdraw_object(struct fscache_object *object) | |
688 | { | |
689 | struct fscache_cookie *cookie; | |
690 | bool detached; | |
691 | ||
692 | _enter(""); | |
693 | ||
694 | spin_lock(&object->lock); | |
695 | cookie = object->cookie; | |
696 | if (cookie) { | |
697 | /* need to get the cookie lock before the object lock, starting | |
698 | * from the object pointer */ | |
699 | atomic_inc(&cookie->usage); | |
700 | spin_unlock(&object->lock); | |
701 | ||
702 | detached = false; | |
703 | spin_lock(&cookie->lock); | |
704 | spin_lock(&object->lock); | |
705 | ||
706 | if (object->cookie == cookie) { | |
707 | hlist_del_init(&object->cookie_link); | |
708 | object->cookie = NULL; | |
709 | detached = true; | |
710 | } | |
711 | spin_unlock(&cookie->lock); | |
712 | fscache_cookie_put(cookie); | |
713 | if (detached) | |
714 | fscache_cookie_put(cookie); | |
715 | } | |
716 | ||
717 | spin_unlock(&object->lock); | |
718 | ||
719 | fscache_drop_object(object); | |
720 | } | |
721 | ||
722 | /* | |
723 | * withdraw an object from active service at the behest of the cache | |
724 | * - need break the links to a cached object cookie | |
725 | * - called under two situations: | |
726 | * (1) recycler decides to reclaim an in-use object | |
727 | * (2) a cache is unmounted | |
728 | * - have to take care as the cookie can be being relinquished by the netfs | |
729 | * simultaneously | |
730 | * - the object is pinned by the caller holding a refcount on it | |
731 | */ | |
732 | void fscache_withdrawing_object(struct fscache_cache *cache, | |
733 | struct fscache_object *object) | |
734 | { | |
735 | bool enqueue = false; | |
736 | ||
737 | _enter(",OBJ%x", object->debug_id); | |
738 | ||
739 | spin_lock(&object->lock); | |
740 | if (object->state < FSCACHE_OBJECT_WITHDRAWING) { | |
741 | object->state = FSCACHE_OBJECT_WITHDRAWING; | |
742 | enqueue = true; | |
743 | } | |
744 | spin_unlock(&object->lock); | |
745 | ||
746 | if (enqueue) | |
747 | fscache_enqueue_object(object); | |
748 | ||
749 | _leave(""); | |
750 | } | |
751 | ||
752 | /* | |
753 | * allow the slow work item processor to get a ref on an object | |
754 | */ | |
755 | static int fscache_object_slow_work_get_ref(struct slow_work *work) | |
756 | { | |
757 | struct fscache_object *object = | |
758 | container_of(work, struct fscache_object, work); | |
52bd75fd | 759 | int ret; |
36c95590 | 760 | |
52bd75fd DH |
761 | fscache_stat(&fscache_n_cop_grab_object); |
762 | ret = object->cache->ops->grab_object(object) ? 0 : -EAGAIN; | |
763 | fscache_stat_d(&fscache_n_cop_grab_object); | |
764 | return ret; | |
36c95590 DH |
765 | } |
766 | ||
767 | /* | |
768 | * allow the slow work item processor to discard a ref on a work item | |
769 | */ | |
770 | static void fscache_object_slow_work_put_ref(struct slow_work *work) | |
771 | { | |
772 | struct fscache_object *object = | |
773 | container_of(work, struct fscache_object, work); | |
774 | ||
52bd75fd DH |
775 | fscache_stat(&fscache_n_cop_put_object); |
776 | object->cache->ops->put_object(object); | |
777 | fscache_stat_d(&fscache_n_cop_put_object); | |
36c95590 DH |
778 | } |
779 | ||
780 | /* | |
781 | * enqueue an object for metadata-type processing | |
782 | */ | |
783 | void fscache_enqueue_object(struct fscache_object *object) | |
784 | { | |
785 | _enter("{OBJ%x}", object->debug_id); | |
786 | ||
787 | slow_work_enqueue(&object->work); | |
788 | } | |
789 | ||
790 | /* | |
791 | * enqueue the dependents of an object for metadata-type processing | |
792 | * - the caller must hold the object's lock | |
793 | * - this may cause an already locked object to wind up being processed again | |
794 | */ | |
795 | static void fscache_enqueue_dependents(struct fscache_object *object) | |
796 | { | |
797 | struct fscache_object *dep; | |
798 | ||
799 | _enter("{OBJ%x}", object->debug_id); | |
800 | ||
801 | if (list_empty(&object->dependents)) | |
802 | return; | |
803 | ||
804 | spin_lock(&object->lock); | |
805 | ||
806 | while (!list_empty(&object->dependents)) { | |
807 | dep = list_entry(object->dependents.next, | |
808 | struct fscache_object, dep_link); | |
809 | list_del_init(&dep->dep_link); | |
810 | ||
811 | ||
812 | /* sort onto appropriate lists */ | |
813 | fscache_enqueue_object(dep); | |
52bd75fd | 814 | fscache_stat(&fscache_n_cop_put_object); |
36c95590 | 815 | dep->cache->ops->put_object(dep); |
52bd75fd | 816 | fscache_stat_d(&fscache_n_cop_put_object); |
36c95590 DH |
817 | |
818 | if (!list_empty(&object->dependents)) | |
819 | cond_resched_lock(&object->lock); | |
820 | } | |
821 | ||
822 | spin_unlock(&object->lock); | |
823 | } | |
824 | ||
825 | /* | |
826 | * remove an object from whatever queue it's waiting on | |
827 | * - the caller must hold object->lock | |
828 | */ | |
829 | void fscache_dequeue_object(struct fscache_object *object) | |
830 | { | |
831 | _enter("{OBJ%x}", object->debug_id); | |
832 | ||
833 | if (!list_empty(&object->dep_link)) { | |
834 | spin_lock(&object->parent->lock); | |
835 | list_del_init(&object->dep_link); | |
836 | spin_unlock(&object->parent->lock); | |
837 | } | |
838 | ||
839 | _leave(""); | |
840 | } | |
841 | ||
842 | /** | |
843 | * fscache_check_aux - Ask the netfs whether an object on disk is still valid | |
844 | * @object: The object to ask about | |
845 | * @data: The auxiliary data for the object | |
846 | * @datalen: The size of the auxiliary data | |
847 | * | |
848 | * This function consults the netfs about the coherency state of an object | |
849 | */ | |
850 | enum fscache_checkaux fscache_check_aux(struct fscache_object *object, | |
851 | const void *data, uint16_t datalen) | |
852 | { | |
853 | enum fscache_checkaux result; | |
854 | ||
855 | if (!object->cookie->def->check_aux) { | |
856 | fscache_stat(&fscache_n_checkaux_none); | |
857 | return FSCACHE_CHECKAUX_OKAY; | |
858 | } | |
859 | ||
860 | result = object->cookie->def->check_aux(object->cookie->netfs_data, | |
861 | data, datalen); | |
862 | switch (result) { | |
863 | /* entry okay as is */ | |
864 | case FSCACHE_CHECKAUX_OKAY: | |
865 | fscache_stat(&fscache_n_checkaux_okay); | |
866 | break; | |
867 | ||
868 | /* entry requires update */ | |
869 | case FSCACHE_CHECKAUX_NEEDS_UPDATE: | |
870 | fscache_stat(&fscache_n_checkaux_update); | |
871 | break; | |
872 | ||
873 | /* entry requires deletion */ | |
874 | case FSCACHE_CHECKAUX_OBSOLETE: | |
875 | fscache_stat(&fscache_n_checkaux_obsolete); | |
876 | break; | |
877 | ||
878 | default: | |
879 | BUG(); | |
880 | } | |
881 | ||
882 | return result; | |
883 | } | |
884 | EXPORT_SYMBOL(fscache_check_aux); |