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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 | ||
440f0aff DH |
36 | fscache_set_op_state(op, "EnQ"); |
37 | ||
5753c441 | 38 | ASSERT(list_empty(&op->pend_link)); |
952efe7b DH |
39 | ASSERT(op->processor != NULL); |
40 | ASSERTCMP(op->object->state, >=, FSCACHE_OBJECT_AVAILABLE); | |
41 | ASSERTCMP(atomic_read(&op->usage), >, 0); | |
42 | ||
5753c441 DH |
43 | fscache_stat(&fscache_n_op_enqueue); |
44 | switch (op->flags & FSCACHE_OP_TYPE) { | |
45 | case FSCACHE_OP_FAST: | |
46 | _debug("queue fast"); | |
47 | atomic_inc(&op->usage); | |
48 | if (!schedule_work(&op->fast_work)) | |
49 | fscache_put_operation(op); | |
50 | break; | |
51 | case FSCACHE_OP_SLOW: | |
52 | _debug("queue slow"); | |
53 | slow_work_enqueue(&op->slow_work); | |
54 | break; | |
55 | case FSCACHE_OP_MYTHREAD: | |
56 | _debug("queue for caller's attention"); | |
57 | break; | |
58 | default: | |
59 | printk(KERN_ERR "FS-Cache: Unexpected op type %lx", | |
60 | op->flags); | |
61 | BUG(); | |
62 | break; | |
952efe7b DH |
63 | } |
64 | } | |
65 | EXPORT_SYMBOL(fscache_enqueue_operation); | |
66 | ||
67 | /* | |
68 | * start an op running | |
69 | */ | |
70 | static void fscache_run_op(struct fscache_object *object, | |
71 | struct fscache_operation *op) | |
72 | { | |
440f0aff DH |
73 | fscache_set_op_state(op, "Run"); |
74 | ||
952efe7b DH |
75 | object->n_in_progress++; |
76 | if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags)) | |
77 | wake_up_bit(&op->flags, FSCACHE_OP_WAITING); | |
78 | if (op->processor) | |
79 | fscache_enqueue_operation(op); | |
80 | fscache_stat(&fscache_n_op_run); | |
81 | } | |
82 | ||
83 | /* | |
84 | * submit an exclusive operation for an object | |
85 | * - other ops are excluded from running simultaneously with this one | |
86 | * - this gets any extra refs it needs on an op | |
87 | */ | |
88 | int fscache_submit_exclusive_op(struct fscache_object *object, | |
89 | struct fscache_operation *op) | |
90 | { | |
91 | int ret; | |
92 | ||
93 | _enter("{OBJ%x OP%x},", object->debug_id, op->debug_id); | |
94 | ||
440f0aff DH |
95 | fscache_set_op_state(op, "SubmitX"); |
96 | ||
952efe7b DH |
97 | spin_lock(&object->lock); |
98 | ASSERTCMP(object->n_ops, >=, object->n_in_progress); | |
99 | ASSERTCMP(object->n_ops, >=, object->n_exclusive); | |
5753c441 | 100 | ASSERT(list_empty(&op->pend_link)); |
952efe7b DH |
101 | |
102 | ret = -ENOBUFS; | |
103 | if (fscache_object_is_active(object)) { | |
104 | op->object = object; | |
105 | object->n_ops++; | |
106 | object->n_exclusive++; /* reads and writes must wait */ | |
107 | ||
108 | if (object->n_ops > 0) { | |
109 | atomic_inc(&op->usage); | |
110 | list_add_tail(&op->pend_link, &object->pending_ops); | |
111 | fscache_stat(&fscache_n_op_pend); | |
112 | } else if (!list_empty(&object->pending_ops)) { | |
113 | atomic_inc(&op->usage); | |
114 | list_add_tail(&op->pend_link, &object->pending_ops); | |
115 | fscache_stat(&fscache_n_op_pend); | |
116 | fscache_start_operations(object); | |
117 | } else { | |
118 | ASSERTCMP(object->n_in_progress, ==, 0); | |
119 | fscache_run_op(object, op); | |
120 | } | |
121 | ||
122 | /* need to issue a new write op after this */ | |
123 | clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); | |
124 | ret = 0; | |
125 | } else if (object->state == FSCACHE_OBJECT_CREATING) { | |
126 | op->object = object; | |
127 | object->n_ops++; | |
128 | object->n_exclusive++; /* reads and writes must wait */ | |
129 | atomic_inc(&op->usage); | |
130 | list_add_tail(&op->pend_link, &object->pending_ops); | |
131 | fscache_stat(&fscache_n_op_pend); | |
132 | ret = 0; | |
133 | } else { | |
134 | /* not allowed to submit ops in any other state */ | |
135 | BUG(); | |
136 | } | |
137 | ||
138 | spin_unlock(&object->lock); | |
139 | return ret; | |
140 | } | |
141 | ||
142 | /* | |
143 | * report an unexpected submission | |
144 | */ | |
145 | static void fscache_report_unexpected_submission(struct fscache_object *object, | |
146 | struct fscache_operation *op, | |
147 | unsigned long ostate) | |
148 | { | |
149 | static bool once_only; | |
150 | struct fscache_operation *p; | |
151 | unsigned n; | |
152 | ||
153 | if (once_only) | |
154 | return; | |
155 | once_only = true; | |
156 | ||
157 | kdebug("unexpected submission OP%x [OBJ%x %s]", | |
158 | op->debug_id, object->debug_id, | |
159 | fscache_object_states[object->state]); | |
160 | kdebug("objstate=%s [%s]", | |
161 | fscache_object_states[object->state], | |
162 | fscache_object_states[ostate]); | |
163 | kdebug("objflags=%lx", object->flags); | |
164 | kdebug("objevent=%lx [%lx]", object->events, object->event_mask); | |
165 | kdebug("ops=%u inp=%u exc=%u", | |
166 | object->n_ops, object->n_in_progress, object->n_exclusive); | |
167 | ||
168 | if (!list_empty(&object->pending_ops)) { | |
169 | n = 0; | |
170 | list_for_each_entry(p, &object->pending_ops, pend_link) { | |
171 | ASSERTCMP(p->object, ==, object); | |
172 | kdebug("%p %p", op->processor, op->release); | |
173 | n++; | |
174 | } | |
175 | ||
176 | kdebug("n=%u", n); | |
177 | } | |
178 | ||
179 | dump_stack(); | |
180 | } | |
181 | ||
182 | /* | |
183 | * submit an operation for an object | |
184 | * - objects may be submitted only in the following states: | |
185 | * - during object creation (write ops may be submitted) | |
186 | * - whilst the object is active | |
187 | * - after an I/O error incurred in one of the two above states (op rejected) | |
188 | * - this gets any extra refs it needs on an op | |
189 | */ | |
190 | int fscache_submit_op(struct fscache_object *object, | |
191 | struct fscache_operation *op) | |
192 | { | |
193 | unsigned long ostate; | |
194 | int ret; | |
195 | ||
196 | _enter("{OBJ%x OP%x},{%u}", | |
197 | object->debug_id, op->debug_id, atomic_read(&op->usage)); | |
198 | ||
199 | ASSERTCMP(atomic_read(&op->usage), >, 0); | |
200 | ||
440f0aff DH |
201 | fscache_set_op_state(op, "Submit"); |
202 | ||
952efe7b DH |
203 | spin_lock(&object->lock); |
204 | ASSERTCMP(object->n_ops, >=, object->n_in_progress); | |
205 | ASSERTCMP(object->n_ops, >=, object->n_exclusive); | |
5753c441 | 206 | ASSERT(list_empty(&op->pend_link)); |
952efe7b DH |
207 | |
208 | ostate = object->state; | |
209 | smp_rmb(); | |
210 | ||
211 | if (fscache_object_is_active(object)) { | |
212 | op->object = object; | |
213 | object->n_ops++; | |
214 | ||
215 | if (object->n_exclusive > 0) { | |
216 | atomic_inc(&op->usage); | |
217 | list_add_tail(&op->pend_link, &object->pending_ops); | |
218 | fscache_stat(&fscache_n_op_pend); | |
219 | } else if (!list_empty(&object->pending_ops)) { | |
220 | atomic_inc(&op->usage); | |
221 | list_add_tail(&op->pend_link, &object->pending_ops); | |
222 | fscache_stat(&fscache_n_op_pend); | |
223 | fscache_start_operations(object); | |
224 | } else { | |
225 | ASSERTCMP(object->n_exclusive, ==, 0); | |
226 | fscache_run_op(object, op); | |
227 | } | |
228 | ret = 0; | |
229 | } else if (object->state == FSCACHE_OBJECT_CREATING) { | |
230 | op->object = object; | |
231 | object->n_ops++; | |
232 | atomic_inc(&op->usage); | |
233 | list_add_tail(&op->pend_link, &object->pending_ops); | |
234 | fscache_stat(&fscache_n_op_pend); | |
235 | ret = 0; | |
e3d4d28b DH |
236 | } else if (object->state == FSCACHE_OBJECT_DYING || |
237 | object->state == FSCACHE_OBJECT_LC_DYING || | |
238 | object->state == FSCACHE_OBJECT_WITHDRAWING) { | |
239 | fscache_stat(&fscache_n_op_rejected); | |
240 | ret = -ENOBUFS; | |
952efe7b DH |
241 | } else if (!test_bit(FSCACHE_IOERROR, &object->cache->flags)) { |
242 | fscache_report_unexpected_submission(object, op, ostate); | |
243 | ASSERT(!fscache_object_is_active(object)); | |
244 | ret = -ENOBUFS; | |
245 | } else { | |
246 | ret = -ENOBUFS; | |
247 | } | |
248 | ||
249 | spin_unlock(&object->lock); | |
250 | return ret; | |
251 | } | |
252 | ||
253 | /* | |
254 | * queue an object for withdrawal on error, aborting all following asynchronous | |
255 | * operations | |
256 | */ | |
257 | void fscache_abort_object(struct fscache_object *object) | |
258 | { | |
259 | _enter("{OBJ%x}", object->debug_id); | |
260 | ||
261 | fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR); | |
262 | } | |
263 | ||
264 | /* | |
265 | * jump start the operation processing on an object | |
266 | * - caller must hold object->lock | |
267 | */ | |
268 | void fscache_start_operations(struct fscache_object *object) | |
269 | { | |
270 | struct fscache_operation *op; | |
271 | bool stop = false; | |
272 | ||
273 | while (!list_empty(&object->pending_ops) && !stop) { | |
274 | op = list_entry(object->pending_ops.next, | |
275 | struct fscache_operation, pend_link); | |
276 | ||
277 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) { | |
278 | if (object->n_in_progress > 0) | |
279 | break; | |
280 | stop = true; | |
281 | } | |
282 | list_del_init(&op->pend_link); | |
5753c441 | 283 | fscache_run_op(object, op); |
952efe7b DH |
284 | |
285 | /* the pending queue was holding a ref on the object */ | |
286 | fscache_put_operation(op); | |
287 | } | |
288 | ||
289 | ASSERTCMP(object->n_in_progress, <=, object->n_ops); | |
290 | ||
291 | _debug("woke %d ops on OBJ%x", | |
292 | object->n_in_progress, object->debug_id); | |
293 | } | |
294 | ||
5753c441 DH |
295 | /* |
296 | * cancel an operation that's pending on an object | |
297 | */ | |
298 | int fscache_cancel_op(struct fscache_operation *op) | |
299 | { | |
300 | struct fscache_object *object = op->object; | |
301 | int ret; | |
302 | ||
303 | _enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id); | |
304 | ||
305 | spin_lock(&object->lock); | |
306 | ||
307 | ret = -EBUSY; | |
308 | if (!list_empty(&op->pend_link)) { | |
309 | fscache_stat(&fscache_n_op_cancelled); | |
310 | list_del_init(&op->pend_link); | |
311 | object->n_ops--; | |
312 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) | |
313 | object->n_exclusive--; | |
314 | if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags)) | |
315 | wake_up_bit(&op->flags, FSCACHE_OP_WAITING); | |
316 | fscache_put_operation(op); | |
317 | ret = 0; | |
318 | } | |
319 | ||
320 | spin_unlock(&object->lock); | |
321 | _leave(" = %d", ret); | |
322 | return ret; | |
323 | } | |
324 | ||
952efe7b DH |
325 | /* |
326 | * release an operation | |
327 | * - queues pending ops if this is the last in-progress op | |
328 | */ | |
329 | void fscache_put_operation(struct fscache_operation *op) | |
330 | { | |
331 | struct fscache_object *object; | |
332 | struct fscache_cache *cache; | |
333 | ||
334 | _enter("{OBJ%x OP%x,%d}", | |
335 | op->object->debug_id, op->debug_id, atomic_read(&op->usage)); | |
336 | ||
337 | ASSERTCMP(atomic_read(&op->usage), >, 0); | |
338 | ||
339 | if (!atomic_dec_and_test(&op->usage)) | |
340 | return; | |
341 | ||
440f0aff DH |
342 | fscache_set_op_state(op, "Put"); |
343 | ||
952efe7b DH |
344 | _debug("PUT OP"); |
345 | if (test_and_set_bit(FSCACHE_OP_DEAD, &op->flags)) | |
346 | BUG(); | |
347 | ||
348 | fscache_stat(&fscache_n_op_release); | |
349 | ||
350 | if (op->release) { | |
351 | op->release(op); | |
352 | op->release = NULL; | |
353 | } | |
354 | ||
355 | object = op->object; | |
356 | ||
4fbf4291 DH |
357 | if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags)) |
358 | atomic_dec(&object->n_reads); | |
359 | ||
952efe7b DH |
360 | /* now... we may get called with the object spinlock held, so we |
361 | * complete the cleanup here only if we can immediately acquire the | |
362 | * lock, and defer it otherwise */ | |
363 | if (!spin_trylock(&object->lock)) { | |
364 | _debug("defer put"); | |
365 | fscache_stat(&fscache_n_op_deferred_release); | |
366 | ||
367 | cache = object->cache; | |
368 | spin_lock(&cache->op_gc_list_lock); | |
369 | list_add_tail(&op->pend_link, &cache->op_gc_list); | |
370 | spin_unlock(&cache->op_gc_list_lock); | |
371 | schedule_work(&cache->op_gc); | |
372 | _leave(" [defer]"); | |
373 | return; | |
374 | } | |
375 | ||
376 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) { | |
377 | ASSERTCMP(object->n_exclusive, >, 0); | |
378 | object->n_exclusive--; | |
379 | } | |
380 | ||
381 | ASSERTCMP(object->n_in_progress, >, 0); | |
382 | object->n_in_progress--; | |
383 | if (object->n_in_progress == 0) | |
384 | fscache_start_operations(object); | |
385 | ||
386 | ASSERTCMP(object->n_ops, >, 0); | |
387 | object->n_ops--; | |
388 | if (object->n_ops == 0) | |
389 | fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED); | |
390 | ||
391 | spin_unlock(&object->lock); | |
392 | ||
393 | kfree(op); | |
394 | _leave(" [done]"); | |
395 | } | |
396 | EXPORT_SYMBOL(fscache_put_operation); | |
397 | ||
398 | /* | |
399 | * garbage collect operations that have had their release deferred | |
400 | */ | |
401 | void fscache_operation_gc(struct work_struct *work) | |
402 | { | |
403 | struct fscache_operation *op; | |
404 | struct fscache_object *object; | |
405 | struct fscache_cache *cache = | |
406 | container_of(work, struct fscache_cache, op_gc); | |
407 | int count = 0; | |
408 | ||
409 | _enter(""); | |
410 | ||
411 | do { | |
412 | spin_lock(&cache->op_gc_list_lock); | |
413 | if (list_empty(&cache->op_gc_list)) { | |
414 | spin_unlock(&cache->op_gc_list_lock); | |
415 | break; | |
416 | } | |
417 | ||
418 | op = list_entry(cache->op_gc_list.next, | |
419 | struct fscache_operation, pend_link); | |
420 | list_del(&op->pend_link); | |
421 | spin_unlock(&cache->op_gc_list_lock); | |
422 | ||
423 | object = op->object; | |
424 | ||
425 | _debug("GC DEFERRED REL OBJ%x OP%x", | |
426 | object->debug_id, op->debug_id); | |
427 | fscache_stat(&fscache_n_op_gc); | |
428 | ||
429 | ASSERTCMP(atomic_read(&op->usage), ==, 0); | |
430 | ||
431 | spin_lock(&object->lock); | |
432 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) { | |
433 | ASSERTCMP(object->n_exclusive, >, 0); | |
434 | object->n_exclusive--; | |
435 | } | |
436 | ||
437 | ASSERTCMP(object->n_in_progress, >, 0); | |
438 | object->n_in_progress--; | |
439 | if (object->n_in_progress == 0) | |
440 | fscache_start_operations(object); | |
441 | ||
442 | ASSERTCMP(object->n_ops, >, 0); | |
443 | object->n_ops--; | |
444 | if (object->n_ops == 0) | |
445 | fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED); | |
446 | ||
447 | spin_unlock(&object->lock); | |
448 | ||
449 | } while (count++ < 20); | |
450 | ||
451 | if (!list_empty(&cache->op_gc_list)) | |
452 | schedule_work(&cache->op_gc); | |
453 | ||
454 | _leave(""); | |
455 | } | |
456 | ||
457 | /* | |
458 | * allow the slow work item processor to get a ref on an operation | |
459 | */ | |
460 | static int fscache_op_get_ref(struct slow_work *work) | |
461 | { | |
462 | struct fscache_operation *op = | |
463 | container_of(work, struct fscache_operation, slow_work); | |
464 | ||
465 | atomic_inc(&op->usage); | |
466 | return 0; | |
467 | } | |
468 | ||
469 | /* | |
470 | * allow the slow work item processor to discard a ref on an operation | |
471 | */ | |
472 | static void fscache_op_put_ref(struct slow_work *work) | |
473 | { | |
474 | struct fscache_operation *op = | |
475 | container_of(work, struct fscache_operation, slow_work); | |
476 | ||
477 | fscache_put_operation(op); | |
478 | } | |
479 | ||
480 | /* | |
481 | * execute an operation using the slow thread pool to provide processing context | |
482 | * - the caller holds a ref to this object, so we don't need to hold one | |
483 | */ | |
484 | static void fscache_op_execute(struct slow_work *work) | |
485 | { | |
486 | struct fscache_operation *op = | |
487 | container_of(work, struct fscache_operation, slow_work); | |
488 | unsigned long start; | |
489 | ||
490 | _enter("{OBJ%x OP%x,%d}", | |
491 | op->object->debug_id, op->debug_id, atomic_read(&op->usage)); | |
492 | ||
493 | ASSERT(op->processor != NULL); | |
494 | start = jiffies; | |
495 | op->processor(op); | |
496 | fscache_hist(fscache_ops_histogram, start); | |
497 | ||
498 | _leave(""); | |
499 | } | |
500 | ||
440f0aff DH |
501 | /* |
502 | * describe an operation for slow-work debugging | |
503 | */ | |
a53f4f9e | 504 | #ifdef CONFIG_SLOW_WORK_DEBUG |
440f0aff DH |
505 | static void fscache_op_desc(struct slow_work *work, struct seq_file *m) |
506 | { | |
507 | struct fscache_operation *op = | |
508 | container_of(work, struct fscache_operation, slow_work); | |
509 | ||
510 | seq_printf(m, "FSC: OBJ%x OP%x: %s/%s fl=%lx", | |
511 | op->object->debug_id, op->debug_id, | |
512 | op->name, op->state, op->flags); | |
513 | } | |
514 | #endif | |
515 | ||
952efe7b | 516 | const struct slow_work_ops fscache_op_slow_work_ops = { |
3d7a641e | 517 | .owner = THIS_MODULE, |
952efe7b DH |
518 | .get_ref = fscache_op_get_ref, |
519 | .put_ref = fscache_op_put_ref, | |
520 | .execute = fscache_op_execute, | |
a53f4f9e | 521 | #ifdef CONFIG_SLOW_WORK_DEBUG |
440f0aff DH |
522 | .desc = fscache_op_desc, |
523 | #endif | |
952efe7b | 524 | }; |