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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; | |
fee096de | 471 | int ret; |
36c95590 DH |
472 | |
473 | _enter(""); | |
474 | ||
475 | parent = object->parent; | |
476 | ASSERT(parent != NULL); | |
477 | ASSERTCMP(parent->n_ops, >, 0); | |
478 | ASSERTCMP(parent->n_obj_ops, >, 0); | |
479 | ||
480 | /* make sure the parent is still available */ | |
481 | ASSERTCMP(parent->state, >=, FSCACHE_OBJECT_AVAILABLE); | |
482 | ||
483 | if (parent->state >= FSCACHE_OBJECT_DYING || | |
484 | test_bit(FSCACHE_IOERROR, &object->cache->flags)) { | |
485 | _debug("unavailable"); | |
486 | set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events); | |
487 | _leave(""); | |
488 | return; | |
489 | } | |
490 | ||
491 | _debug("LOOKUP \"%s/%s\" in \"%s\"", | |
492 | parent->cookie->def->name, cookie->def->name, | |
493 | object->cache->tag->name); | |
494 | ||
495 | fscache_stat(&fscache_n_object_lookups); | |
52bd75fd | 496 | fscache_stat(&fscache_n_cop_lookup_object); |
fee096de | 497 | ret = object->cache->ops->lookup_object(object); |
52bd75fd | 498 | fscache_stat_d(&fscache_n_cop_lookup_object); |
36c95590 DH |
499 | |
500 | if (test_bit(FSCACHE_OBJECT_EV_ERROR, &object->events)) | |
501 | set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags); | |
502 | ||
fee096de DH |
503 | if (ret == -ETIMEDOUT) { |
504 | /* probably stuck behind another object, so move this one to | |
505 | * the back of the queue */ | |
506 | fscache_stat(&fscache_n_object_lookups_timed_out); | |
507 | set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events); | |
508 | } | |
509 | ||
36c95590 DH |
510 | _leave(""); |
511 | } | |
512 | ||
513 | /** | |
514 | * fscache_object_lookup_negative - Note negative cookie lookup | |
515 | * @object: Object pointing to cookie to mark | |
516 | * | |
517 | * Note negative lookup, permitting those waiting to read data from an already | |
518 | * existing backing object to continue as there's no data for them to read. | |
519 | */ | |
520 | void fscache_object_lookup_negative(struct fscache_object *object) | |
521 | { | |
522 | struct fscache_cookie *cookie = object->cookie; | |
523 | ||
524 | _enter("{OBJ%x,%s}", | |
525 | object->debug_id, fscache_object_states[object->state]); | |
526 | ||
527 | spin_lock(&object->lock); | |
528 | if (object->state == FSCACHE_OBJECT_LOOKING_UP) { | |
529 | fscache_stat(&fscache_n_object_lookups_negative); | |
530 | ||
531 | /* transit here to allow write requests to begin stacking up | |
532 | * and read requests to begin returning ENODATA */ | |
533 | object->state = FSCACHE_OBJECT_CREATING; | |
534 | spin_unlock(&object->lock); | |
535 | ||
536 | set_bit(FSCACHE_COOKIE_PENDING_FILL, &cookie->flags); | |
537 | set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags); | |
538 | ||
539 | _debug("wake up lookup %p", &cookie->flags); | |
540 | smp_mb__before_clear_bit(); | |
541 | clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags); | |
542 | smp_mb__after_clear_bit(); | |
543 | wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP); | |
544 | set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events); | |
545 | } else { | |
546 | ASSERTCMP(object->state, ==, FSCACHE_OBJECT_CREATING); | |
547 | spin_unlock(&object->lock); | |
548 | } | |
549 | ||
550 | _leave(""); | |
551 | } | |
552 | EXPORT_SYMBOL(fscache_object_lookup_negative); | |
553 | ||
554 | /** | |
555 | * fscache_obtained_object - Note successful object lookup or creation | |
556 | * @object: Object pointing to cookie to mark | |
557 | * | |
558 | * Note successful lookup and/or creation, permitting those waiting to write | |
559 | * data to a backing object to continue. | |
560 | * | |
561 | * Note that after calling this, an object's cookie may be relinquished by the | |
562 | * netfs, and so must be accessed with object lock held. | |
563 | */ | |
564 | void fscache_obtained_object(struct fscache_object *object) | |
565 | { | |
566 | struct fscache_cookie *cookie = object->cookie; | |
567 | ||
568 | _enter("{OBJ%x,%s}", | |
569 | object->debug_id, fscache_object_states[object->state]); | |
570 | ||
571 | /* if we were still looking up, then we must have a positive lookup | |
572 | * result, in which case there may be data available */ | |
573 | spin_lock(&object->lock); | |
574 | if (object->state == FSCACHE_OBJECT_LOOKING_UP) { | |
575 | fscache_stat(&fscache_n_object_lookups_positive); | |
576 | ||
577 | clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags); | |
578 | ||
579 | object->state = FSCACHE_OBJECT_AVAILABLE; | |
580 | spin_unlock(&object->lock); | |
581 | ||
582 | smp_mb__before_clear_bit(); | |
583 | clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags); | |
584 | smp_mb__after_clear_bit(); | |
585 | wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP); | |
586 | set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events); | |
587 | } else { | |
588 | ASSERTCMP(object->state, ==, FSCACHE_OBJECT_CREATING); | |
589 | fscache_stat(&fscache_n_object_created); | |
590 | ||
591 | object->state = FSCACHE_OBJECT_AVAILABLE; | |
592 | spin_unlock(&object->lock); | |
593 | set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events); | |
594 | smp_wmb(); | |
595 | } | |
596 | ||
597 | if (test_and_clear_bit(FSCACHE_COOKIE_CREATING, &cookie->flags)) | |
598 | wake_up_bit(&cookie->flags, FSCACHE_COOKIE_CREATING); | |
599 | ||
600 | _leave(""); | |
601 | } | |
602 | EXPORT_SYMBOL(fscache_obtained_object); | |
603 | ||
604 | /* | |
605 | * handle an object that has just become available | |
606 | */ | |
607 | static void fscache_object_available(struct fscache_object *object) | |
608 | { | |
609 | _enter("{OBJ%x}", object->debug_id); | |
610 | ||
611 | spin_lock(&object->lock); | |
612 | ||
6897e3df DH |
613 | if (object->cookie && |
614 | test_and_clear_bit(FSCACHE_COOKIE_CREATING, &object->cookie->flags)) | |
36c95590 DH |
615 | wake_up_bit(&object->cookie->flags, FSCACHE_COOKIE_CREATING); |
616 | ||
617 | fscache_done_parent_op(object); | |
618 | if (object->n_in_progress == 0) { | |
619 | if (object->n_ops > 0) { | |
620 | ASSERTCMP(object->n_ops, >=, object->n_obj_ops); | |
621 | ASSERTIF(object->n_ops > object->n_obj_ops, | |
622 | !list_empty(&object->pending_ops)); | |
623 | fscache_start_operations(object); | |
624 | } else { | |
625 | ASSERT(list_empty(&object->pending_ops)); | |
626 | } | |
627 | } | |
628 | spin_unlock(&object->lock); | |
629 | ||
52bd75fd | 630 | fscache_stat(&fscache_n_cop_lookup_complete); |
36c95590 | 631 | object->cache->ops->lookup_complete(object); |
52bd75fd | 632 | fscache_stat_d(&fscache_n_cop_lookup_complete); |
36c95590 DH |
633 | fscache_enqueue_dependents(object); |
634 | ||
635 | fscache_hist(fscache_obj_instantiate_histogram, object->lookup_jif); | |
636 | fscache_stat(&fscache_n_object_avail); | |
637 | ||
638 | _leave(""); | |
639 | } | |
640 | ||
641 | /* | |
642 | * drop an object's attachments | |
643 | */ | |
644 | static void fscache_drop_object(struct fscache_object *object) | |
645 | { | |
646 | struct fscache_object *parent = object->parent; | |
647 | struct fscache_cache *cache = object->cache; | |
648 | ||
649 | _enter("{OBJ%x,%d}", object->debug_id, object->n_children); | |
650 | ||
6897e3df DH |
651 | ASSERTCMP(object->cookie, ==, NULL); |
652 | ASSERT(hlist_unhashed(&object->cookie_link)); | |
653 | ||
36c95590 DH |
654 | spin_lock(&cache->object_list_lock); |
655 | list_del_init(&object->cache_link); | |
656 | spin_unlock(&cache->object_list_lock); | |
657 | ||
52bd75fd | 658 | fscache_stat(&fscache_n_cop_drop_object); |
36c95590 | 659 | cache->ops->drop_object(object); |
52bd75fd | 660 | fscache_stat_d(&fscache_n_cop_drop_object); |
36c95590 DH |
661 | |
662 | if (parent) { | |
663 | _debug("release parent OBJ%x {%d}", | |
664 | parent->debug_id, parent->n_children); | |
665 | ||
666 | spin_lock(&parent->lock); | |
667 | parent->n_children--; | |
668 | if (parent->n_children == 0) | |
669 | fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED); | |
670 | spin_unlock(&parent->lock); | |
671 | object->parent = NULL; | |
672 | } | |
673 | ||
674 | /* this just shifts the object release to the slow work processor */ | |
52bd75fd | 675 | fscache_stat(&fscache_n_cop_put_object); |
36c95590 | 676 | object->cache->ops->put_object(object); |
52bd75fd | 677 | fscache_stat_d(&fscache_n_cop_put_object); |
36c95590 DH |
678 | |
679 | _leave(""); | |
680 | } | |
681 | ||
682 | /* | |
683 | * release or recycle an object that the netfs has discarded | |
684 | */ | |
685 | static void fscache_release_object(struct fscache_object *object) | |
686 | { | |
687 | _enter(""); | |
688 | ||
689 | fscache_drop_object(object); | |
690 | } | |
691 | ||
692 | /* | |
693 | * withdraw an object from active service | |
694 | */ | |
695 | static void fscache_withdraw_object(struct fscache_object *object) | |
696 | { | |
697 | struct fscache_cookie *cookie; | |
698 | bool detached; | |
699 | ||
700 | _enter(""); | |
701 | ||
702 | spin_lock(&object->lock); | |
703 | cookie = object->cookie; | |
704 | if (cookie) { | |
705 | /* need to get the cookie lock before the object lock, starting | |
706 | * from the object pointer */ | |
707 | atomic_inc(&cookie->usage); | |
708 | spin_unlock(&object->lock); | |
709 | ||
710 | detached = false; | |
711 | spin_lock(&cookie->lock); | |
712 | spin_lock(&object->lock); | |
713 | ||
714 | if (object->cookie == cookie) { | |
715 | hlist_del_init(&object->cookie_link); | |
716 | object->cookie = NULL; | |
717 | detached = true; | |
718 | } | |
719 | spin_unlock(&cookie->lock); | |
720 | fscache_cookie_put(cookie); | |
721 | if (detached) | |
722 | fscache_cookie_put(cookie); | |
723 | } | |
724 | ||
725 | spin_unlock(&object->lock); | |
726 | ||
727 | fscache_drop_object(object); | |
728 | } | |
729 | ||
730 | /* | |
731 | * withdraw an object from active service at the behest of the cache | |
732 | * - need break the links to a cached object cookie | |
733 | * - called under two situations: | |
734 | * (1) recycler decides to reclaim an in-use object | |
735 | * (2) a cache is unmounted | |
736 | * - have to take care as the cookie can be being relinquished by the netfs | |
737 | * simultaneously | |
738 | * - the object is pinned by the caller holding a refcount on it | |
739 | */ | |
740 | void fscache_withdrawing_object(struct fscache_cache *cache, | |
741 | struct fscache_object *object) | |
742 | { | |
743 | bool enqueue = false; | |
744 | ||
745 | _enter(",OBJ%x", object->debug_id); | |
746 | ||
747 | spin_lock(&object->lock); | |
748 | if (object->state < FSCACHE_OBJECT_WITHDRAWING) { | |
749 | object->state = FSCACHE_OBJECT_WITHDRAWING; | |
750 | enqueue = true; | |
751 | } | |
752 | spin_unlock(&object->lock); | |
753 | ||
754 | if (enqueue) | |
755 | fscache_enqueue_object(object); | |
756 | ||
757 | _leave(""); | |
758 | } | |
759 | ||
760 | /* | |
761 | * allow the slow work item processor to get a ref on an object | |
762 | */ | |
763 | static int fscache_object_slow_work_get_ref(struct slow_work *work) | |
764 | { | |
765 | struct fscache_object *object = | |
766 | container_of(work, struct fscache_object, work); | |
52bd75fd | 767 | int ret; |
36c95590 | 768 | |
52bd75fd DH |
769 | fscache_stat(&fscache_n_cop_grab_object); |
770 | ret = object->cache->ops->grab_object(object) ? 0 : -EAGAIN; | |
771 | fscache_stat_d(&fscache_n_cop_grab_object); | |
772 | return ret; | |
36c95590 DH |
773 | } |
774 | ||
775 | /* | |
776 | * allow the slow work item processor to discard a ref on a work item | |
777 | */ | |
778 | static void fscache_object_slow_work_put_ref(struct slow_work *work) | |
779 | { | |
780 | struct fscache_object *object = | |
781 | container_of(work, struct fscache_object, work); | |
782 | ||
52bd75fd DH |
783 | fscache_stat(&fscache_n_cop_put_object); |
784 | object->cache->ops->put_object(object); | |
785 | fscache_stat_d(&fscache_n_cop_put_object); | |
36c95590 DH |
786 | } |
787 | ||
788 | /* | |
789 | * enqueue an object for metadata-type processing | |
790 | */ | |
791 | void fscache_enqueue_object(struct fscache_object *object) | |
792 | { | |
793 | _enter("{OBJ%x}", object->debug_id); | |
794 | ||
795 | slow_work_enqueue(&object->work); | |
796 | } | |
797 | ||
798 | /* | |
799 | * enqueue the dependents of an object for metadata-type processing | |
800 | * - the caller must hold the object's lock | |
801 | * - this may cause an already locked object to wind up being processed again | |
802 | */ | |
803 | static void fscache_enqueue_dependents(struct fscache_object *object) | |
804 | { | |
805 | struct fscache_object *dep; | |
806 | ||
807 | _enter("{OBJ%x}", object->debug_id); | |
808 | ||
809 | if (list_empty(&object->dependents)) | |
810 | return; | |
811 | ||
812 | spin_lock(&object->lock); | |
813 | ||
814 | while (!list_empty(&object->dependents)) { | |
815 | dep = list_entry(object->dependents.next, | |
816 | struct fscache_object, dep_link); | |
817 | list_del_init(&dep->dep_link); | |
818 | ||
819 | ||
820 | /* sort onto appropriate lists */ | |
821 | fscache_enqueue_object(dep); | |
52bd75fd | 822 | fscache_stat(&fscache_n_cop_put_object); |
36c95590 | 823 | dep->cache->ops->put_object(dep); |
52bd75fd | 824 | fscache_stat_d(&fscache_n_cop_put_object); |
36c95590 DH |
825 | |
826 | if (!list_empty(&object->dependents)) | |
827 | cond_resched_lock(&object->lock); | |
828 | } | |
829 | ||
830 | spin_unlock(&object->lock); | |
831 | } | |
832 | ||
833 | /* | |
834 | * remove an object from whatever queue it's waiting on | |
835 | * - the caller must hold object->lock | |
836 | */ | |
837 | void fscache_dequeue_object(struct fscache_object *object) | |
838 | { | |
839 | _enter("{OBJ%x}", object->debug_id); | |
840 | ||
841 | if (!list_empty(&object->dep_link)) { | |
842 | spin_lock(&object->parent->lock); | |
843 | list_del_init(&object->dep_link); | |
844 | spin_unlock(&object->parent->lock); | |
845 | } | |
846 | ||
847 | _leave(""); | |
848 | } | |
849 | ||
850 | /** | |
851 | * fscache_check_aux - Ask the netfs whether an object on disk is still valid | |
852 | * @object: The object to ask about | |
853 | * @data: The auxiliary data for the object | |
854 | * @datalen: The size of the auxiliary data | |
855 | * | |
856 | * This function consults the netfs about the coherency state of an object | |
857 | */ | |
858 | enum fscache_checkaux fscache_check_aux(struct fscache_object *object, | |
859 | const void *data, uint16_t datalen) | |
860 | { | |
861 | enum fscache_checkaux result; | |
862 | ||
863 | if (!object->cookie->def->check_aux) { | |
864 | fscache_stat(&fscache_n_checkaux_none); | |
865 | return FSCACHE_CHECKAUX_OKAY; | |
866 | } | |
867 | ||
868 | result = object->cookie->def->check_aux(object->cookie->netfs_data, | |
869 | data, datalen); | |
870 | switch (result) { | |
871 | /* entry okay as is */ | |
872 | case FSCACHE_CHECKAUX_OKAY: | |
873 | fscache_stat(&fscache_n_checkaux_okay); | |
874 | break; | |
875 | ||
876 | /* entry requires update */ | |
877 | case FSCACHE_CHECKAUX_NEEDS_UPDATE: | |
878 | fscache_stat(&fscache_n_checkaux_update); | |
879 | break; | |
880 | ||
881 | /* entry requires deletion */ | |
882 | case FSCACHE_CHECKAUX_OBSOLETE: | |
883 | fscache_stat(&fscache_n_checkaux_obsolete); | |
884 | break; | |
885 | ||
886 | default: | |
887 | BUG(); | |
888 | } | |
889 | ||
890 | return result; | |
891 | } | |
892 | EXPORT_SYMBOL(fscache_check_aux); |