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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> |
952efe7b DH |
17 | #include "internal.h" |
18 | ||
19 | atomic_t fscache_op_debug_id; | |
20 | EXPORT_SYMBOL(fscache_op_debug_id); | |
21 | ||
22 | /** | |
23 | * fscache_enqueue_operation - Enqueue an operation for processing | |
24 | * @op: The operation to enqueue | |
25 | * | |
26 | * Enqueue an operation for processing by the FS-Cache thread pool. | |
27 | * | |
28 | * This will get its own ref on the object. | |
29 | */ | |
30 | void fscache_enqueue_operation(struct fscache_operation *op) | |
31 | { | |
32 | _enter("{OBJ%x OP%x,%u}", | |
33 | op->object->debug_id, op->debug_id, atomic_read(&op->usage)); | |
34 | ||
440f0aff DH |
35 | fscache_set_op_state(op, "EnQ"); |
36 | ||
5753c441 | 37 | ASSERT(list_empty(&op->pend_link)); |
952efe7b DH |
38 | ASSERT(op->processor != NULL); |
39 | ASSERTCMP(op->object->state, >=, FSCACHE_OBJECT_AVAILABLE); | |
40 | ASSERTCMP(atomic_read(&op->usage), >, 0); | |
41 | ||
5753c441 DH |
42 | fscache_stat(&fscache_n_op_enqueue); |
43 | switch (op->flags & FSCACHE_OP_TYPE) { | |
44 | case FSCACHE_OP_FAST: | |
45 | _debug("queue fast"); | |
46 | atomic_inc(&op->usage); | |
47 | if (!schedule_work(&op->fast_work)) | |
48 | fscache_put_operation(op); | |
49 | break; | |
50 | case FSCACHE_OP_SLOW: | |
51 | _debug("queue slow"); | |
52 | slow_work_enqueue(&op->slow_work); | |
53 | break; | |
54 | case FSCACHE_OP_MYTHREAD: | |
55 | _debug("queue for caller's attention"); | |
56 | break; | |
57 | default: | |
58 | printk(KERN_ERR "FS-Cache: Unexpected op type %lx", | |
59 | op->flags); | |
60 | BUG(); | |
61 | break; | |
952efe7b DH |
62 | } |
63 | } | |
64 | EXPORT_SYMBOL(fscache_enqueue_operation); | |
65 | ||
66 | /* | |
67 | * start an op running | |
68 | */ | |
69 | static void fscache_run_op(struct fscache_object *object, | |
70 | struct fscache_operation *op) | |
71 | { | |
440f0aff DH |
72 | fscache_set_op_state(op, "Run"); |
73 | ||
952efe7b DH |
74 | object->n_in_progress++; |
75 | if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags)) | |
76 | wake_up_bit(&op->flags, FSCACHE_OP_WAITING); | |
77 | if (op->processor) | |
78 | fscache_enqueue_operation(op); | |
79 | fscache_stat(&fscache_n_op_run); | |
80 | } | |
81 | ||
82 | /* | |
83 | * submit an exclusive operation for an object | |
84 | * - other ops are excluded from running simultaneously with this one | |
85 | * - this gets any extra refs it needs on an op | |
86 | */ | |
87 | int fscache_submit_exclusive_op(struct fscache_object *object, | |
88 | struct fscache_operation *op) | |
89 | { | |
90 | int ret; | |
91 | ||
92 | _enter("{OBJ%x OP%x},", object->debug_id, op->debug_id); | |
93 | ||
440f0aff DH |
94 | fscache_set_op_state(op, "SubmitX"); |
95 | ||
952efe7b DH |
96 | spin_lock(&object->lock); |
97 | ASSERTCMP(object->n_ops, >=, object->n_in_progress); | |
98 | ASSERTCMP(object->n_ops, >=, object->n_exclusive); | |
5753c441 | 99 | ASSERT(list_empty(&op->pend_link)); |
952efe7b DH |
100 | |
101 | ret = -ENOBUFS; | |
102 | if (fscache_object_is_active(object)) { | |
103 | op->object = object; | |
104 | object->n_ops++; | |
105 | object->n_exclusive++; /* reads and writes must wait */ | |
106 | ||
107 | if (object->n_ops > 0) { | |
108 | atomic_inc(&op->usage); | |
109 | list_add_tail(&op->pend_link, &object->pending_ops); | |
110 | fscache_stat(&fscache_n_op_pend); | |
111 | } else if (!list_empty(&object->pending_ops)) { | |
112 | atomic_inc(&op->usage); | |
113 | list_add_tail(&op->pend_link, &object->pending_ops); | |
114 | fscache_stat(&fscache_n_op_pend); | |
115 | fscache_start_operations(object); | |
116 | } else { | |
117 | ASSERTCMP(object->n_in_progress, ==, 0); | |
118 | fscache_run_op(object, op); | |
119 | } | |
120 | ||
121 | /* need to issue a new write op after this */ | |
122 | clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); | |
123 | ret = 0; | |
124 | } else if (object->state == FSCACHE_OBJECT_CREATING) { | |
125 | op->object = object; | |
126 | object->n_ops++; | |
127 | object->n_exclusive++; /* reads and writes must wait */ | |
128 | atomic_inc(&op->usage); | |
129 | list_add_tail(&op->pend_link, &object->pending_ops); | |
130 | fscache_stat(&fscache_n_op_pend); | |
131 | ret = 0; | |
132 | } else { | |
133 | /* not allowed to submit ops in any other state */ | |
134 | BUG(); | |
135 | } | |
136 | ||
137 | spin_unlock(&object->lock); | |
138 | return ret; | |
139 | } | |
140 | ||
141 | /* | |
142 | * report an unexpected submission | |
143 | */ | |
144 | static void fscache_report_unexpected_submission(struct fscache_object *object, | |
145 | struct fscache_operation *op, | |
146 | unsigned long ostate) | |
147 | { | |
148 | static bool once_only; | |
149 | struct fscache_operation *p; | |
150 | unsigned n; | |
151 | ||
152 | if (once_only) | |
153 | return; | |
154 | once_only = true; | |
155 | ||
156 | kdebug("unexpected submission OP%x [OBJ%x %s]", | |
157 | op->debug_id, object->debug_id, | |
158 | fscache_object_states[object->state]); | |
159 | kdebug("objstate=%s [%s]", | |
160 | fscache_object_states[object->state], | |
161 | fscache_object_states[ostate]); | |
162 | kdebug("objflags=%lx", object->flags); | |
163 | kdebug("objevent=%lx [%lx]", object->events, object->event_mask); | |
164 | kdebug("ops=%u inp=%u exc=%u", | |
165 | object->n_ops, object->n_in_progress, object->n_exclusive); | |
166 | ||
167 | if (!list_empty(&object->pending_ops)) { | |
168 | n = 0; | |
169 | list_for_each_entry(p, &object->pending_ops, pend_link) { | |
170 | ASSERTCMP(p->object, ==, object); | |
171 | kdebug("%p %p", op->processor, op->release); | |
172 | n++; | |
173 | } | |
174 | ||
175 | kdebug("n=%u", n); | |
176 | } | |
177 | ||
178 | dump_stack(); | |
179 | } | |
180 | ||
181 | /* | |
182 | * submit an operation for an object | |
183 | * - objects may be submitted only in the following states: | |
184 | * - during object creation (write ops may be submitted) | |
185 | * - whilst the object is active | |
186 | * - after an I/O error incurred in one of the two above states (op rejected) | |
187 | * - this gets any extra refs it needs on an op | |
188 | */ | |
189 | int fscache_submit_op(struct fscache_object *object, | |
190 | struct fscache_operation *op) | |
191 | { | |
192 | unsigned long ostate; | |
193 | int ret; | |
194 | ||
195 | _enter("{OBJ%x OP%x},{%u}", | |
196 | object->debug_id, op->debug_id, atomic_read(&op->usage)); | |
197 | ||
198 | ASSERTCMP(atomic_read(&op->usage), >, 0); | |
199 | ||
440f0aff DH |
200 | fscache_set_op_state(op, "Submit"); |
201 | ||
952efe7b DH |
202 | spin_lock(&object->lock); |
203 | ASSERTCMP(object->n_ops, >=, object->n_in_progress); | |
204 | ASSERTCMP(object->n_ops, >=, object->n_exclusive); | |
5753c441 | 205 | ASSERT(list_empty(&op->pend_link)); |
952efe7b DH |
206 | |
207 | ostate = object->state; | |
208 | smp_rmb(); | |
209 | ||
210 | if (fscache_object_is_active(object)) { | |
211 | op->object = object; | |
212 | object->n_ops++; | |
213 | ||
214 | if (object->n_exclusive > 0) { | |
215 | atomic_inc(&op->usage); | |
216 | list_add_tail(&op->pend_link, &object->pending_ops); | |
217 | fscache_stat(&fscache_n_op_pend); | |
218 | } else if (!list_empty(&object->pending_ops)) { | |
219 | atomic_inc(&op->usage); | |
220 | list_add_tail(&op->pend_link, &object->pending_ops); | |
221 | fscache_stat(&fscache_n_op_pend); | |
222 | fscache_start_operations(object); | |
223 | } else { | |
224 | ASSERTCMP(object->n_exclusive, ==, 0); | |
225 | fscache_run_op(object, op); | |
226 | } | |
227 | ret = 0; | |
228 | } else if (object->state == FSCACHE_OBJECT_CREATING) { | |
229 | op->object = object; | |
230 | object->n_ops++; | |
231 | atomic_inc(&op->usage); | |
232 | list_add_tail(&op->pend_link, &object->pending_ops); | |
233 | fscache_stat(&fscache_n_op_pend); | |
234 | ret = 0; | |
e3d4d28b DH |
235 | } else if (object->state == FSCACHE_OBJECT_DYING || |
236 | object->state == FSCACHE_OBJECT_LC_DYING || | |
237 | object->state == FSCACHE_OBJECT_WITHDRAWING) { | |
238 | fscache_stat(&fscache_n_op_rejected); | |
239 | ret = -ENOBUFS; | |
952efe7b DH |
240 | } else if (!test_bit(FSCACHE_IOERROR, &object->cache->flags)) { |
241 | fscache_report_unexpected_submission(object, op, ostate); | |
242 | ASSERT(!fscache_object_is_active(object)); | |
243 | ret = -ENOBUFS; | |
244 | } else { | |
245 | ret = -ENOBUFS; | |
246 | } | |
247 | ||
248 | spin_unlock(&object->lock); | |
249 | return ret; | |
250 | } | |
251 | ||
252 | /* | |
253 | * queue an object for withdrawal on error, aborting all following asynchronous | |
254 | * operations | |
255 | */ | |
256 | void fscache_abort_object(struct fscache_object *object) | |
257 | { | |
258 | _enter("{OBJ%x}", object->debug_id); | |
259 | ||
260 | fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR); | |
261 | } | |
262 | ||
263 | /* | |
264 | * jump start the operation processing on an object | |
265 | * - caller must hold object->lock | |
266 | */ | |
267 | void fscache_start_operations(struct fscache_object *object) | |
268 | { | |
269 | struct fscache_operation *op; | |
270 | bool stop = false; | |
271 | ||
272 | while (!list_empty(&object->pending_ops) && !stop) { | |
273 | op = list_entry(object->pending_ops.next, | |
274 | struct fscache_operation, pend_link); | |
275 | ||
276 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) { | |
277 | if (object->n_in_progress > 0) | |
278 | break; | |
279 | stop = true; | |
280 | } | |
281 | list_del_init(&op->pend_link); | |
5753c441 | 282 | fscache_run_op(object, op); |
952efe7b DH |
283 | |
284 | /* the pending queue was holding a ref on the object */ | |
285 | fscache_put_operation(op); | |
286 | } | |
287 | ||
288 | ASSERTCMP(object->n_in_progress, <=, object->n_ops); | |
289 | ||
290 | _debug("woke %d ops on OBJ%x", | |
291 | object->n_in_progress, object->debug_id); | |
292 | } | |
293 | ||
5753c441 DH |
294 | /* |
295 | * cancel an operation that's pending on an object | |
296 | */ | |
297 | int fscache_cancel_op(struct fscache_operation *op) | |
298 | { | |
299 | struct fscache_object *object = op->object; | |
300 | int ret; | |
301 | ||
302 | _enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id); | |
303 | ||
304 | spin_lock(&object->lock); | |
305 | ||
306 | ret = -EBUSY; | |
307 | if (!list_empty(&op->pend_link)) { | |
308 | fscache_stat(&fscache_n_op_cancelled); | |
309 | list_del_init(&op->pend_link); | |
310 | object->n_ops--; | |
311 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) | |
312 | object->n_exclusive--; | |
313 | if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags)) | |
314 | wake_up_bit(&op->flags, FSCACHE_OP_WAITING); | |
315 | fscache_put_operation(op); | |
316 | ret = 0; | |
317 | } | |
318 | ||
319 | spin_unlock(&object->lock); | |
320 | _leave(" = %d", ret); | |
321 | return ret; | |
322 | } | |
323 | ||
952efe7b DH |
324 | /* |
325 | * release an operation | |
326 | * - queues pending ops if this is the last in-progress op | |
327 | */ | |
328 | void fscache_put_operation(struct fscache_operation *op) | |
329 | { | |
330 | struct fscache_object *object; | |
331 | struct fscache_cache *cache; | |
332 | ||
333 | _enter("{OBJ%x OP%x,%d}", | |
334 | op->object->debug_id, op->debug_id, atomic_read(&op->usage)); | |
335 | ||
336 | ASSERTCMP(atomic_read(&op->usage), >, 0); | |
337 | ||
338 | if (!atomic_dec_and_test(&op->usage)) | |
339 | return; | |
340 | ||
440f0aff DH |
341 | fscache_set_op_state(op, "Put"); |
342 | ||
952efe7b DH |
343 | _debug("PUT OP"); |
344 | if (test_and_set_bit(FSCACHE_OP_DEAD, &op->flags)) | |
345 | BUG(); | |
346 | ||
347 | fscache_stat(&fscache_n_op_release); | |
348 | ||
349 | if (op->release) { | |
350 | op->release(op); | |
351 | op->release = NULL; | |
352 | } | |
353 | ||
354 | object = op->object; | |
355 | ||
4fbf4291 DH |
356 | if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags)) |
357 | atomic_dec(&object->n_reads); | |
358 | ||
952efe7b DH |
359 | /* now... we may get called with the object spinlock held, so we |
360 | * complete the cleanup here only if we can immediately acquire the | |
361 | * lock, and defer it otherwise */ | |
362 | if (!spin_trylock(&object->lock)) { | |
363 | _debug("defer put"); | |
364 | fscache_stat(&fscache_n_op_deferred_release); | |
365 | ||
366 | cache = object->cache; | |
367 | spin_lock(&cache->op_gc_list_lock); | |
368 | list_add_tail(&op->pend_link, &cache->op_gc_list); | |
369 | spin_unlock(&cache->op_gc_list_lock); | |
370 | schedule_work(&cache->op_gc); | |
371 | _leave(" [defer]"); | |
372 | return; | |
373 | } | |
374 | ||
375 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) { | |
376 | ASSERTCMP(object->n_exclusive, >, 0); | |
377 | object->n_exclusive--; | |
378 | } | |
379 | ||
380 | ASSERTCMP(object->n_in_progress, >, 0); | |
381 | object->n_in_progress--; | |
382 | if (object->n_in_progress == 0) | |
383 | fscache_start_operations(object); | |
384 | ||
385 | ASSERTCMP(object->n_ops, >, 0); | |
386 | object->n_ops--; | |
387 | if (object->n_ops == 0) | |
388 | fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED); | |
389 | ||
390 | spin_unlock(&object->lock); | |
391 | ||
392 | kfree(op); | |
393 | _leave(" [done]"); | |
394 | } | |
395 | EXPORT_SYMBOL(fscache_put_operation); | |
396 | ||
397 | /* | |
398 | * garbage collect operations that have had their release deferred | |
399 | */ | |
400 | void fscache_operation_gc(struct work_struct *work) | |
401 | { | |
402 | struct fscache_operation *op; | |
403 | struct fscache_object *object; | |
404 | struct fscache_cache *cache = | |
405 | container_of(work, struct fscache_cache, op_gc); | |
406 | int count = 0; | |
407 | ||
408 | _enter(""); | |
409 | ||
410 | do { | |
411 | spin_lock(&cache->op_gc_list_lock); | |
412 | if (list_empty(&cache->op_gc_list)) { | |
413 | spin_unlock(&cache->op_gc_list_lock); | |
414 | break; | |
415 | } | |
416 | ||
417 | op = list_entry(cache->op_gc_list.next, | |
418 | struct fscache_operation, pend_link); | |
419 | list_del(&op->pend_link); | |
420 | spin_unlock(&cache->op_gc_list_lock); | |
421 | ||
422 | object = op->object; | |
423 | ||
424 | _debug("GC DEFERRED REL OBJ%x OP%x", | |
425 | object->debug_id, op->debug_id); | |
426 | fscache_stat(&fscache_n_op_gc); | |
427 | ||
428 | ASSERTCMP(atomic_read(&op->usage), ==, 0); | |
429 | ||
430 | spin_lock(&object->lock); | |
431 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) { | |
432 | ASSERTCMP(object->n_exclusive, >, 0); | |
433 | object->n_exclusive--; | |
434 | } | |
435 | ||
436 | ASSERTCMP(object->n_in_progress, >, 0); | |
437 | object->n_in_progress--; | |
438 | if (object->n_in_progress == 0) | |
439 | fscache_start_operations(object); | |
440 | ||
441 | ASSERTCMP(object->n_ops, >, 0); | |
442 | object->n_ops--; | |
443 | if (object->n_ops == 0) | |
444 | fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED); | |
445 | ||
446 | spin_unlock(&object->lock); | |
447 | ||
448 | } while (count++ < 20); | |
449 | ||
450 | if (!list_empty(&cache->op_gc_list)) | |
451 | schedule_work(&cache->op_gc); | |
452 | ||
453 | _leave(""); | |
454 | } | |
455 | ||
456 | /* | |
457 | * allow the slow work item processor to get a ref on an operation | |
458 | */ | |
459 | static int fscache_op_get_ref(struct slow_work *work) | |
460 | { | |
461 | struct fscache_operation *op = | |
462 | container_of(work, struct fscache_operation, slow_work); | |
463 | ||
464 | atomic_inc(&op->usage); | |
465 | return 0; | |
466 | } | |
467 | ||
468 | /* | |
469 | * allow the slow work item processor to discard a ref on an operation | |
470 | */ | |
471 | static void fscache_op_put_ref(struct slow_work *work) | |
472 | { | |
473 | struct fscache_operation *op = | |
474 | container_of(work, struct fscache_operation, slow_work); | |
475 | ||
476 | fscache_put_operation(op); | |
477 | } | |
478 | ||
479 | /* | |
480 | * execute an operation using the slow thread pool to provide processing context | |
481 | * - the caller holds a ref to this object, so we don't need to hold one | |
482 | */ | |
483 | static void fscache_op_execute(struct slow_work *work) | |
484 | { | |
485 | struct fscache_operation *op = | |
486 | container_of(work, struct fscache_operation, slow_work); | |
487 | unsigned long start; | |
488 | ||
489 | _enter("{OBJ%x OP%x,%d}", | |
490 | op->object->debug_id, op->debug_id, atomic_read(&op->usage)); | |
491 | ||
492 | ASSERT(op->processor != NULL); | |
493 | start = jiffies; | |
494 | op->processor(op); | |
495 | fscache_hist(fscache_ops_histogram, start); | |
496 | ||
497 | _leave(""); | |
498 | } | |
499 | ||
440f0aff DH |
500 | /* |
501 | * describe an operation for slow-work debugging | |
502 | */ | |
a53f4f9e | 503 | #ifdef CONFIG_SLOW_WORK_DEBUG |
440f0aff DH |
504 | static void fscache_op_desc(struct slow_work *work, struct seq_file *m) |
505 | { | |
506 | struct fscache_operation *op = | |
507 | container_of(work, struct fscache_operation, slow_work); | |
508 | ||
509 | seq_printf(m, "FSC: OBJ%x OP%x: %s/%s fl=%lx", | |
510 | op->object->debug_id, op->debug_id, | |
511 | op->name, op->state, op->flags); | |
512 | } | |
513 | #endif | |
514 | ||
952efe7b | 515 | const struct slow_work_ops fscache_op_slow_work_ops = { |
3d7a641e | 516 | .owner = THIS_MODULE, |
952efe7b DH |
517 | .get_ref = fscache_op_get_ref, |
518 | .put_ref = fscache_op_put_ref, | |
519 | .execute = fscache_op_execute, | |
a53f4f9e | 520 | #ifdef CONFIG_SLOW_WORK_DEBUG |
440f0aff DH |
521 | .desc = fscache_op_desc, |
522 | #endif | |
952efe7b | 523 | }; |