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952efe7b DH |
1 | /* FS-Cache worker operation management routines |
2 | * | |
3 | * Copyright (C) 2008 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/operations.txt | |
12 | */ | |
13 | ||
14 | #define FSCACHE_DEBUG_LEVEL OPERATION | |
15 | #include <linux/module.h> | |
440f0aff | 16 | #include <linux/seq_file.h> |
5a0e3ad6 | 17 | #include <linux/slab.h> |
952efe7b DH |
18 | #include "internal.h" |
19 | ||
20 | atomic_t fscache_op_debug_id; | |
21 | EXPORT_SYMBOL(fscache_op_debug_id); | |
22 | ||
23 | /** | |
24 | * fscache_enqueue_operation - Enqueue an operation for processing | |
25 | * @op: The operation to enqueue | |
26 | * | |
27 | * Enqueue an operation for processing by the FS-Cache thread pool. | |
28 | * | |
29 | * This will get its own ref on the object. | |
30 | */ | |
31 | void fscache_enqueue_operation(struct fscache_operation *op) | |
32 | { | |
33 | _enter("{OBJ%x OP%x,%u}", | |
34 | op->object->debug_id, op->debug_id, atomic_read(&op->usage)); | |
35 | ||
5753c441 | 36 | ASSERT(list_empty(&op->pend_link)); |
952efe7b DH |
37 | ASSERT(op->processor != NULL); |
38 | ASSERTCMP(op->object->state, >=, FSCACHE_OBJECT_AVAILABLE); | |
39 | ASSERTCMP(atomic_read(&op->usage), >, 0); | |
9f10523f | 40 | ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS); |
952efe7b | 41 | |
5753c441 DH |
42 | fscache_stat(&fscache_n_op_enqueue); |
43 | switch (op->flags & FSCACHE_OP_TYPE) { | |
8af7c124 TH |
44 | case FSCACHE_OP_ASYNC: |
45 | _debug("queue async"); | |
5753c441 | 46 | atomic_inc(&op->usage); |
8af7c124 | 47 | if (!queue_work(fscache_op_wq, &op->work)) |
5753c441 DH |
48 | fscache_put_operation(op); |
49 | break; | |
5753c441 DH |
50 | case FSCACHE_OP_MYTHREAD: |
51 | _debug("queue for caller's attention"); | |
52 | break; | |
53 | default: | |
54 | printk(KERN_ERR "FS-Cache: Unexpected op type %lx", | |
55 | op->flags); | |
56 | BUG(); | |
57 | break; | |
952efe7b DH |
58 | } |
59 | } | |
60 | EXPORT_SYMBOL(fscache_enqueue_operation); | |
61 | ||
62 | /* | |
63 | * start an op running | |
64 | */ | |
65 | static void fscache_run_op(struct fscache_object *object, | |
66 | struct fscache_operation *op) | |
67 | { | |
9f10523f DH |
68 | ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING); |
69 | ||
70 | op->state = FSCACHE_OP_ST_IN_PROGRESS; | |
952efe7b DH |
71 | object->n_in_progress++; |
72 | if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags)) | |
73 | wake_up_bit(&op->flags, FSCACHE_OP_WAITING); | |
74 | if (op->processor) | |
75 | fscache_enqueue_operation(op); | |
76 | fscache_stat(&fscache_n_op_run); | |
77 | } | |
78 | ||
79 | /* | |
80 | * submit an exclusive operation for an object | |
81 | * - other ops are excluded from running simultaneously with this one | |
82 | * - this gets any extra refs it needs on an op | |
83 | */ | |
84 | int fscache_submit_exclusive_op(struct fscache_object *object, | |
85 | struct fscache_operation *op) | |
86 | { | |
952efe7b DH |
87 | _enter("{OBJ%x OP%x},", object->debug_id, op->debug_id); |
88 | ||
9f10523f DH |
89 | ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED); |
90 | ASSERTCMP(atomic_read(&op->usage), >, 0); | |
91 | ||
952efe7b DH |
92 | spin_lock(&object->lock); |
93 | ASSERTCMP(object->n_ops, >=, object->n_in_progress); | |
94 | ASSERTCMP(object->n_ops, >=, object->n_exclusive); | |
5753c441 | 95 | ASSERT(list_empty(&op->pend_link)); |
952efe7b | 96 | |
9f10523f | 97 | op->state = FSCACHE_OP_ST_PENDING; |
952efe7b DH |
98 | if (fscache_object_is_active(object)) { |
99 | op->object = object; | |
100 | object->n_ops++; | |
101 | object->n_exclusive++; /* reads and writes must wait */ | |
102 | ||
9f10523f | 103 | if (object->n_in_progress > 0) { |
952efe7b DH |
104 | atomic_inc(&op->usage); |
105 | list_add_tail(&op->pend_link, &object->pending_ops); | |
106 | fscache_stat(&fscache_n_op_pend); | |
107 | } else if (!list_empty(&object->pending_ops)) { | |
108 | atomic_inc(&op->usage); | |
109 | list_add_tail(&op->pend_link, &object->pending_ops); | |
110 | fscache_stat(&fscache_n_op_pend); | |
111 | fscache_start_operations(object); | |
112 | } else { | |
113 | ASSERTCMP(object->n_in_progress, ==, 0); | |
114 | fscache_run_op(object, op); | |
115 | } | |
116 | ||
117 | /* need to issue a new write op after this */ | |
118 | clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); | |
952efe7b DH |
119 | } else if (object->state == FSCACHE_OBJECT_CREATING) { |
120 | op->object = object; | |
121 | object->n_ops++; | |
122 | object->n_exclusive++; /* reads and writes must wait */ | |
123 | atomic_inc(&op->usage); | |
124 | list_add_tail(&op->pend_link, &object->pending_ops); | |
125 | fscache_stat(&fscache_n_op_pend); | |
952efe7b DH |
126 | } else { |
127 | /* not allowed to submit ops in any other state */ | |
128 | BUG(); | |
129 | } | |
130 | ||
131 | spin_unlock(&object->lock); | |
9f10523f | 132 | return 0; |
952efe7b DH |
133 | } |
134 | ||
135 | /* | |
136 | * report an unexpected submission | |
137 | */ | |
138 | static void fscache_report_unexpected_submission(struct fscache_object *object, | |
139 | struct fscache_operation *op, | |
140 | unsigned long ostate) | |
141 | { | |
142 | static bool once_only; | |
143 | struct fscache_operation *p; | |
144 | unsigned n; | |
145 | ||
146 | if (once_only) | |
147 | return; | |
148 | once_only = true; | |
149 | ||
150 | kdebug("unexpected submission OP%x [OBJ%x %s]", | |
151 | op->debug_id, object->debug_id, | |
152 | fscache_object_states[object->state]); | |
153 | kdebug("objstate=%s [%s]", | |
154 | fscache_object_states[object->state], | |
155 | fscache_object_states[ostate]); | |
156 | kdebug("objflags=%lx", object->flags); | |
157 | kdebug("objevent=%lx [%lx]", object->events, object->event_mask); | |
158 | kdebug("ops=%u inp=%u exc=%u", | |
159 | object->n_ops, object->n_in_progress, object->n_exclusive); | |
160 | ||
161 | if (!list_empty(&object->pending_ops)) { | |
162 | n = 0; | |
163 | list_for_each_entry(p, &object->pending_ops, pend_link) { | |
164 | ASSERTCMP(p->object, ==, object); | |
165 | kdebug("%p %p", op->processor, op->release); | |
166 | n++; | |
167 | } | |
168 | ||
169 | kdebug("n=%u", n); | |
170 | } | |
171 | ||
172 | dump_stack(); | |
173 | } | |
174 | ||
175 | /* | |
176 | * submit an operation for an object | |
177 | * - objects may be submitted only in the following states: | |
178 | * - during object creation (write ops may be submitted) | |
179 | * - whilst the object is active | |
180 | * - after an I/O error incurred in one of the two above states (op rejected) | |
181 | * - this gets any extra refs it needs on an op | |
182 | */ | |
183 | int fscache_submit_op(struct fscache_object *object, | |
184 | struct fscache_operation *op) | |
185 | { | |
186 | unsigned long ostate; | |
187 | int ret; | |
188 | ||
189 | _enter("{OBJ%x OP%x},{%u}", | |
190 | object->debug_id, op->debug_id, atomic_read(&op->usage)); | |
191 | ||
9f10523f | 192 | ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED); |
952efe7b DH |
193 | ASSERTCMP(atomic_read(&op->usage), >, 0); |
194 | ||
195 | spin_lock(&object->lock); | |
196 | ASSERTCMP(object->n_ops, >=, object->n_in_progress); | |
197 | ASSERTCMP(object->n_ops, >=, object->n_exclusive); | |
5753c441 | 198 | ASSERT(list_empty(&op->pend_link)); |
952efe7b DH |
199 | |
200 | ostate = object->state; | |
201 | smp_rmb(); | |
202 | ||
9f10523f | 203 | op->state = FSCACHE_OP_ST_PENDING; |
952efe7b DH |
204 | if (fscache_object_is_active(object)) { |
205 | op->object = object; | |
206 | object->n_ops++; | |
207 | ||
208 | if (object->n_exclusive > 0) { | |
209 | atomic_inc(&op->usage); | |
210 | list_add_tail(&op->pend_link, &object->pending_ops); | |
211 | fscache_stat(&fscache_n_op_pend); | |
212 | } else if (!list_empty(&object->pending_ops)) { | |
213 | atomic_inc(&op->usage); | |
214 | list_add_tail(&op->pend_link, &object->pending_ops); | |
215 | fscache_stat(&fscache_n_op_pend); | |
216 | fscache_start_operations(object); | |
217 | } else { | |
218 | ASSERTCMP(object->n_exclusive, ==, 0); | |
219 | fscache_run_op(object, op); | |
220 | } | |
221 | ret = 0; | |
222 | } else if (object->state == FSCACHE_OBJECT_CREATING) { | |
223 | op->object = object; | |
224 | object->n_ops++; | |
225 | atomic_inc(&op->usage); | |
226 | list_add_tail(&op->pend_link, &object->pending_ops); | |
227 | fscache_stat(&fscache_n_op_pend); | |
228 | ret = 0; | |
e3d4d28b DH |
229 | } else if (object->state == FSCACHE_OBJECT_DYING || |
230 | object->state == FSCACHE_OBJECT_LC_DYING || | |
231 | object->state == FSCACHE_OBJECT_WITHDRAWING) { | |
232 | fscache_stat(&fscache_n_op_rejected); | |
9f10523f | 233 | op->state = FSCACHE_OP_ST_CANCELLED; |
e3d4d28b | 234 | ret = -ENOBUFS; |
952efe7b DH |
235 | } else if (!test_bit(FSCACHE_IOERROR, &object->cache->flags)) { |
236 | fscache_report_unexpected_submission(object, op, ostate); | |
237 | ASSERT(!fscache_object_is_active(object)); | |
9f10523f | 238 | op->state = FSCACHE_OP_ST_CANCELLED; |
952efe7b DH |
239 | ret = -ENOBUFS; |
240 | } else { | |
9f10523f | 241 | op->state = FSCACHE_OP_ST_CANCELLED; |
952efe7b DH |
242 | ret = -ENOBUFS; |
243 | } | |
244 | ||
245 | spin_unlock(&object->lock); | |
246 | return ret; | |
247 | } | |
248 | ||
249 | /* | |
250 | * queue an object for withdrawal on error, aborting all following asynchronous | |
251 | * operations | |
252 | */ | |
253 | void fscache_abort_object(struct fscache_object *object) | |
254 | { | |
255 | _enter("{OBJ%x}", object->debug_id); | |
256 | ||
257 | fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR); | |
258 | } | |
259 | ||
260 | /* | |
261 | * jump start the operation processing on an object | |
262 | * - caller must hold object->lock | |
263 | */ | |
264 | void fscache_start_operations(struct fscache_object *object) | |
265 | { | |
266 | struct fscache_operation *op; | |
267 | bool stop = false; | |
268 | ||
269 | while (!list_empty(&object->pending_ops) && !stop) { | |
270 | op = list_entry(object->pending_ops.next, | |
271 | struct fscache_operation, pend_link); | |
272 | ||
273 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) { | |
274 | if (object->n_in_progress > 0) | |
275 | break; | |
276 | stop = true; | |
277 | } | |
278 | list_del_init(&op->pend_link); | |
5753c441 | 279 | fscache_run_op(object, op); |
952efe7b DH |
280 | |
281 | /* the pending queue was holding a ref on the object */ | |
282 | fscache_put_operation(op); | |
283 | } | |
284 | ||
285 | ASSERTCMP(object->n_in_progress, <=, object->n_ops); | |
286 | ||
287 | _debug("woke %d ops on OBJ%x", | |
288 | object->n_in_progress, object->debug_id); | |
289 | } | |
290 | ||
5753c441 DH |
291 | /* |
292 | * cancel an operation that's pending on an object | |
293 | */ | |
294 | int fscache_cancel_op(struct fscache_operation *op) | |
295 | { | |
296 | struct fscache_object *object = op->object; | |
297 | int ret; | |
298 | ||
299 | _enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id); | |
300 | ||
9f10523f DH |
301 | ASSERTCMP(op->state, >=, FSCACHE_OP_ST_PENDING); |
302 | ASSERTCMP(op->state, !=, FSCACHE_OP_ST_CANCELLED); | |
303 | ASSERTCMP(atomic_read(&op->usage), >, 0); | |
304 | ||
5753c441 DH |
305 | spin_lock(&object->lock); |
306 | ||
307 | ret = -EBUSY; | |
9f10523f DH |
308 | if (op->state == FSCACHE_OP_ST_PENDING) { |
309 | ASSERT(!list_empty(&op->pend_link)); | |
5753c441 DH |
310 | fscache_stat(&fscache_n_op_cancelled); |
311 | list_del_init(&op->pend_link); | |
9f10523f | 312 | op->state = FSCACHE_OP_ST_CANCELLED; |
5753c441 DH |
313 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) |
314 | object->n_exclusive--; | |
315 | if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags)) | |
316 | wake_up_bit(&op->flags, FSCACHE_OP_WAITING); | |
317 | fscache_put_operation(op); | |
318 | ret = 0; | |
319 | } | |
320 | ||
321 | spin_unlock(&object->lock); | |
322 | _leave(" = %d", ret); | |
323 | return ret; | |
324 | } | |
325 | ||
ef778e7a DH |
326 | /* |
327 | * Cancel all pending operations on an object | |
328 | */ | |
329 | void fscache_cancel_all_ops(struct fscache_object *object) | |
330 | { | |
331 | struct fscache_operation *op; | |
332 | ||
333 | _enter("OBJ%x", object->debug_id); | |
334 | ||
335 | spin_lock(&object->lock); | |
336 | ||
337 | while (!list_empty(&object->pending_ops)) { | |
338 | op = list_entry(object->pending_ops.next, | |
339 | struct fscache_operation, pend_link); | |
340 | fscache_stat(&fscache_n_op_cancelled); | |
341 | list_del_init(&op->pend_link); | |
342 | ||
343 | ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING); | |
344 | op->state = FSCACHE_OP_ST_CANCELLED; | |
345 | ||
346 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) | |
347 | object->n_exclusive--; | |
348 | if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags)) | |
349 | wake_up_bit(&op->flags, FSCACHE_OP_WAITING); | |
350 | fscache_put_operation(op); | |
351 | cond_resched_lock(&object->lock); | |
352 | } | |
353 | ||
354 | spin_unlock(&object->lock); | |
355 | _leave(""); | |
356 | } | |
357 | ||
9f10523f DH |
358 | /* |
359 | * Record the completion of an in-progress operation. | |
360 | */ | |
361 | void fscache_op_complete(struct fscache_operation *op) | |
362 | { | |
363 | struct fscache_object *object = op->object; | |
364 | ||
365 | _enter("OBJ%x", object->debug_id); | |
366 | ||
367 | ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS); | |
368 | ASSERTCMP(object->n_in_progress, >, 0); | |
369 | ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags), | |
370 | object->n_exclusive, >, 0); | |
371 | ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags), | |
372 | object->n_in_progress, ==, 1); | |
373 | ||
374 | spin_lock(&object->lock); | |
375 | ||
376 | op->state = FSCACHE_OP_ST_COMPLETE; | |
377 | ||
378 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) | |
379 | object->n_exclusive--; | |
380 | object->n_in_progress--; | |
381 | if (object->n_in_progress == 0) | |
382 | fscache_start_operations(object); | |
383 | ||
384 | spin_unlock(&object->lock); | |
385 | _leave(""); | |
386 | } | |
387 | EXPORT_SYMBOL(fscache_op_complete); | |
388 | ||
952efe7b DH |
389 | /* |
390 | * release an operation | |
391 | * - queues pending ops if this is the last in-progress op | |
392 | */ | |
393 | void fscache_put_operation(struct fscache_operation *op) | |
394 | { | |
395 | struct fscache_object *object; | |
396 | struct fscache_cache *cache; | |
397 | ||
398 | _enter("{OBJ%x OP%x,%d}", | |
399 | op->object->debug_id, op->debug_id, atomic_read(&op->usage)); | |
400 | ||
401 | ASSERTCMP(atomic_read(&op->usage), >, 0); | |
402 | ||
403 | if (!atomic_dec_and_test(&op->usage)) | |
404 | return; | |
405 | ||
406 | _debug("PUT OP"); | |
9f10523f DH |
407 | ASSERTIFCMP(op->state != FSCACHE_OP_ST_COMPLETE, |
408 | op->state, ==, FSCACHE_OP_ST_CANCELLED); | |
409 | op->state = FSCACHE_OP_ST_DEAD; | |
952efe7b DH |
410 | |
411 | fscache_stat(&fscache_n_op_release); | |
412 | ||
413 | if (op->release) { | |
414 | op->release(op); | |
415 | op->release = NULL; | |
416 | } | |
417 | ||
418 | object = op->object; | |
419 | ||
ef46ed88 DH |
420 | if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags)) { |
421 | if (atomic_dec_and_test(&object->n_reads)) { | |
422 | clear_bit(FSCACHE_COOKIE_WAITING_ON_READS, | |
423 | &object->cookie->flags); | |
424 | wake_up_bit(&object->cookie->flags, | |
425 | FSCACHE_COOKIE_WAITING_ON_READS); | |
426 | } | |
427 | } | |
4fbf4291 | 428 | |
952efe7b DH |
429 | /* now... we may get called with the object spinlock held, so we |
430 | * complete the cleanup here only if we can immediately acquire the | |
431 | * lock, and defer it otherwise */ | |
432 | if (!spin_trylock(&object->lock)) { | |
433 | _debug("defer put"); | |
434 | fscache_stat(&fscache_n_op_deferred_release); | |
435 | ||
436 | cache = object->cache; | |
437 | spin_lock(&cache->op_gc_list_lock); | |
438 | list_add_tail(&op->pend_link, &cache->op_gc_list); | |
439 | spin_unlock(&cache->op_gc_list_lock); | |
440 | schedule_work(&cache->op_gc); | |
441 | _leave(" [defer]"); | |
442 | return; | |
443 | } | |
444 | ||
952efe7b DH |
445 | ASSERTCMP(object->n_ops, >, 0); |
446 | object->n_ops--; | |
447 | if (object->n_ops == 0) | |
448 | fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED); | |
449 | ||
450 | spin_unlock(&object->lock); | |
451 | ||
452 | kfree(op); | |
453 | _leave(" [done]"); | |
454 | } | |
455 | EXPORT_SYMBOL(fscache_put_operation); | |
456 | ||
457 | /* | |
458 | * garbage collect operations that have had their release deferred | |
459 | */ | |
460 | void fscache_operation_gc(struct work_struct *work) | |
461 | { | |
462 | struct fscache_operation *op; | |
463 | struct fscache_object *object; | |
464 | struct fscache_cache *cache = | |
465 | container_of(work, struct fscache_cache, op_gc); | |
466 | int count = 0; | |
467 | ||
468 | _enter(""); | |
469 | ||
470 | do { | |
471 | spin_lock(&cache->op_gc_list_lock); | |
472 | if (list_empty(&cache->op_gc_list)) { | |
473 | spin_unlock(&cache->op_gc_list_lock); | |
474 | break; | |
475 | } | |
476 | ||
477 | op = list_entry(cache->op_gc_list.next, | |
478 | struct fscache_operation, pend_link); | |
479 | list_del(&op->pend_link); | |
480 | spin_unlock(&cache->op_gc_list_lock); | |
481 | ||
482 | object = op->object; | |
9f10523f | 483 | spin_lock(&object->lock); |
952efe7b DH |
484 | |
485 | _debug("GC DEFERRED REL OBJ%x OP%x", | |
486 | object->debug_id, op->debug_id); | |
487 | fscache_stat(&fscache_n_op_gc); | |
488 | ||
489 | ASSERTCMP(atomic_read(&op->usage), ==, 0); | |
9f10523f | 490 | ASSERTCMP(op->state, ==, FSCACHE_OP_ST_DEAD); |
952efe7b DH |
491 | |
492 | ASSERTCMP(object->n_ops, >, 0); | |
493 | object->n_ops--; | |
494 | if (object->n_ops == 0) | |
495 | fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED); | |
496 | ||
497 | spin_unlock(&object->lock); | |
9f10523f | 498 | kfree(op); |
952efe7b DH |
499 | |
500 | } while (count++ < 20); | |
501 | ||
502 | if (!list_empty(&cache->op_gc_list)) | |
503 | schedule_work(&cache->op_gc); | |
504 | ||
505 | _leave(""); | |
506 | } | |
507 | ||
508 | /* | |
8af7c124 TH |
509 | * execute an operation using fs_op_wq to provide processing context - |
510 | * the caller holds a ref to this object, so we don't need to hold one | |
952efe7b | 511 | */ |
8af7c124 | 512 | void fscache_op_work_func(struct work_struct *work) |
952efe7b DH |
513 | { |
514 | struct fscache_operation *op = | |
8af7c124 | 515 | container_of(work, struct fscache_operation, work); |
952efe7b DH |
516 | unsigned long start; |
517 | ||
518 | _enter("{OBJ%x OP%x,%d}", | |
519 | op->object->debug_id, op->debug_id, atomic_read(&op->usage)); | |
520 | ||
521 | ASSERT(op->processor != NULL); | |
522 | start = jiffies; | |
523 | op->processor(op); | |
524 | fscache_hist(fscache_ops_histogram, start); | |
8af7c124 | 525 | fscache_put_operation(op); |
952efe7b DH |
526 | |
527 | _leave(""); | |
528 | } |