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>
16 #include <linux/seq_file.h>
17 #include <linux/slab.h>
18 #include "internal.h"
19
20 atomic_t fscache_op_debug_id;
21 EXPORT_SYMBOL(fscache_op_debug_id);
22
fscache_operation_dummy_cancel(struct fscache_operation * op)23 static void fscache_operation_dummy_cancel(struct fscache_operation *op)
24 {
25 }
26
27 /**
28 * fscache_operation_init - Do basic initialisation of an operation
29 * @op: The operation to initialise
30 * @release: The release function to assign
31 *
32 * Do basic initialisation of an operation. The caller must still set flags,
33 * object and processor if needed.
34 */
fscache_operation_init(struct fscache_operation * op,fscache_operation_processor_t processor,fscache_operation_cancel_t cancel,fscache_operation_release_t release)35 void fscache_operation_init(struct fscache_operation *op,
36 fscache_operation_processor_t processor,
37 fscache_operation_cancel_t cancel,
38 fscache_operation_release_t release)
39 {
40 INIT_WORK(&op->work, fscache_op_work_func);
41 atomic_set(&op->usage, 1);
42 op->state = FSCACHE_OP_ST_INITIALISED;
43 op->debug_id = atomic_inc_return(&fscache_op_debug_id);
44 op->processor = processor;
45 op->cancel = cancel ?: fscache_operation_dummy_cancel;
46 op->release = release;
47 INIT_LIST_HEAD(&op->pend_link);
48 fscache_stat(&fscache_n_op_initialised);
49 }
50 EXPORT_SYMBOL(fscache_operation_init);
51
52 /**
53 * fscache_enqueue_operation - Enqueue an operation for processing
54 * @op: The operation to enqueue
55 *
56 * Enqueue an operation for processing by the FS-Cache thread pool.
57 *
58 * This will get its own ref on the object.
59 */
fscache_enqueue_operation(struct fscache_operation * op)60 void fscache_enqueue_operation(struct fscache_operation *op)
61 {
62 _enter("{OBJ%x OP%x,%u}",
63 op->object->debug_id, op->debug_id, atomic_read(&op->usage));
64
65 ASSERT(list_empty(&op->pend_link));
66 ASSERT(op->processor != NULL);
67 ASSERT(fscache_object_is_available(op->object));
68 ASSERTCMP(atomic_read(&op->usage), >, 0);
69 ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS);
70
71 fscache_stat(&fscache_n_op_enqueue);
72 switch (op->flags & FSCACHE_OP_TYPE) {
73 case FSCACHE_OP_ASYNC:
74 _debug("queue async");
75 atomic_inc(&op->usage);
76 if (!queue_work(fscache_op_wq, &op->work))
77 fscache_put_operation(op);
78 break;
79 case FSCACHE_OP_MYTHREAD:
80 _debug("queue for caller's attention");
81 break;
82 default:
83 pr_err("Unexpected op type %lx", op->flags);
84 BUG();
85 break;
86 }
87 }
88 EXPORT_SYMBOL(fscache_enqueue_operation);
89
90 /*
91 * start an op running
92 */
fscache_run_op(struct fscache_object * object,struct fscache_operation * op)93 static void fscache_run_op(struct fscache_object *object,
94 struct fscache_operation *op)
95 {
96 ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);
97
98 op->state = FSCACHE_OP_ST_IN_PROGRESS;
99 object->n_in_progress++;
100 if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
101 wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
102 if (op->processor)
103 fscache_enqueue_operation(op);
104 fscache_stat(&fscache_n_op_run);
105 }
106
107 /*
108 * report an unexpected submission
109 */
fscache_report_unexpected_submission(struct fscache_object * object,struct fscache_operation * op,const struct fscache_state * ostate)110 static void fscache_report_unexpected_submission(struct fscache_object *object,
111 struct fscache_operation *op,
112 const struct fscache_state *ostate)
113 {
114 static bool once_only;
115 struct fscache_operation *p;
116 unsigned n;
117
118 if (once_only)
119 return;
120 once_only = true;
121
122 kdebug("unexpected submission OP%x [OBJ%x %s]",
123 op->debug_id, object->debug_id, object->state->name);
124 kdebug("objstate=%s [%s]", object->state->name, ostate->name);
125 kdebug("objflags=%lx", object->flags);
126 kdebug("objevent=%lx [%lx]", object->events, object->event_mask);
127 kdebug("ops=%u inp=%u exc=%u",
128 object->n_ops, object->n_in_progress, object->n_exclusive);
129
130 if (!list_empty(&object->pending_ops)) {
131 n = 0;
132 list_for_each_entry(p, &object->pending_ops, pend_link) {
133 ASSERTCMP(p->object, ==, object);
134 kdebug("%p %p", op->processor, op->release);
135 n++;
136 }
137
138 kdebug("n=%u", n);
139 }
140
141 dump_stack();
142 }
143
144 /*
145 * submit an exclusive operation for an object
146 * - other ops are excluded from running simultaneously with this one
147 * - this gets any extra refs it needs on an op
148 */
fscache_submit_exclusive_op(struct fscache_object * object,struct fscache_operation * op)149 int fscache_submit_exclusive_op(struct fscache_object *object,
150 struct fscache_operation *op)
151 {
152 const struct fscache_state *ostate;
153 unsigned long flags;
154 int ret;
155
156 _enter("{OBJ%x OP%x},", object->debug_id, op->debug_id);
157
158 ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
159 ASSERTCMP(atomic_read(&op->usage), >, 0);
160
161 spin_lock(&object->lock);
162 ASSERTCMP(object->n_ops, >=, object->n_in_progress);
163 ASSERTCMP(object->n_ops, >=, object->n_exclusive);
164 ASSERT(list_empty(&op->pend_link));
165
166 ostate = object->state;
167 smp_rmb();
168
169 op->state = FSCACHE_OP_ST_PENDING;
170 flags = READ_ONCE(object->flags);
171 if (unlikely(!(flags & BIT(FSCACHE_OBJECT_IS_LIVE)))) {
172 fscache_stat(&fscache_n_op_rejected);
173 op->cancel(op);
174 op->state = FSCACHE_OP_ST_CANCELLED;
175 ret = -ENOBUFS;
176 } else if (unlikely(fscache_cache_is_broken(object))) {
177 op->cancel(op);
178 op->state = FSCACHE_OP_ST_CANCELLED;
179 ret = -EIO;
180 } else if (flags & BIT(FSCACHE_OBJECT_IS_AVAILABLE)) {
181 op->object = object;
182 object->n_ops++;
183 object->n_exclusive++; /* reads and writes must wait */
184
185 if (object->n_in_progress > 0) {
186 atomic_inc(&op->usage);
187 list_add_tail(&op->pend_link, &object->pending_ops);
188 fscache_stat(&fscache_n_op_pend);
189 } else if (!list_empty(&object->pending_ops)) {
190 atomic_inc(&op->usage);
191 list_add_tail(&op->pend_link, &object->pending_ops);
192 fscache_stat(&fscache_n_op_pend);
193 fscache_start_operations(object);
194 } else {
195 ASSERTCMP(object->n_in_progress, ==, 0);
196 fscache_run_op(object, op);
197 }
198
199 /* need to issue a new write op after this */
200 clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
201 ret = 0;
202 } else if (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
203 op->object = object;
204 object->n_ops++;
205 object->n_exclusive++; /* reads and writes must wait */
206 atomic_inc(&op->usage);
207 list_add_tail(&op->pend_link, &object->pending_ops);
208 fscache_stat(&fscache_n_op_pend);
209 ret = 0;
210 } else if (flags & BIT(FSCACHE_OBJECT_KILLED_BY_CACHE)) {
211 op->cancel(op);
212 op->state = FSCACHE_OP_ST_CANCELLED;
213 ret = -ENOBUFS;
214 } else {
215 fscache_report_unexpected_submission(object, op, ostate);
216 op->cancel(op);
217 op->state = FSCACHE_OP_ST_CANCELLED;
218 ret = -ENOBUFS;
219 }
220
221 spin_unlock(&object->lock);
222 return ret;
223 }
224
225 /*
226 * submit an operation for an object
227 * - objects may be submitted only in the following states:
228 * - during object creation (write ops may be submitted)
229 * - whilst the object is active
230 * - after an I/O error incurred in one of the two above states (op rejected)
231 * - this gets any extra refs it needs on an op
232 */
fscache_submit_op(struct fscache_object * object,struct fscache_operation * op)233 int fscache_submit_op(struct fscache_object *object,
234 struct fscache_operation *op)
235 {
236 const struct fscache_state *ostate;
237 unsigned long flags;
238 int ret;
239
240 _enter("{OBJ%x OP%x},{%u}",
241 object->debug_id, op->debug_id, atomic_read(&op->usage));
242
243 ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
244 ASSERTCMP(atomic_read(&op->usage), >, 0);
245
246 spin_lock(&object->lock);
247 ASSERTCMP(object->n_ops, >=, object->n_in_progress);
248 ASSERTCMP(object->n_ops, >=, object->n_exclusive);
249 ASSERT(list_empty(&op->pend_link));
250
251 ostate = object->state;
252 smp_rmb();
253
254 op->state = FSCACHE_OP_ST_PENDING;
255 flags = READ_ONCE(object->flags);
256 if (unlikely(!(flags & BIT(FSCACHE_OBJECT_IS_LIVE)))) {
257 fscache_stat(&fscache_n_op_rejected);
258 op->cancel(op);
259 op->state = FSCACHE_OP_ST_CANCELLED;
260 ret = -ENOBUFS;
261 } else if (unlikely(fscache_cache_is_broken(object))) {
262 op->cancel(op);
263 op->state = FSCACHE_OP_ST_CANCELLED;
264 ret = -EIO;
265 } else if (flags & BIT(FSCACHE_OBJECT_IS_AVAILABLE)) {
266 op->object = object;
267 object->n_ops++;
268
269 if (object->n_exclusive > 0) {
270 atomic_inc(&op->usage);
271 list_add_tail(&op->pend_link, &object->pending_ops);
272 fscache_stat(&fscache_n_op_pend);
273 } else if (!list_empty(&object->pending_ops)) {
274 atomic_inc(&op->usage);
275 list_add_tail(&op->pend_link, &object->pending_ops);
276 fscache_stat(&fscache_n_op_pend);
277 fscache_start_operations(object);
278 } else {
279 ASSERTCMP(object->n_exclusive, ==, 0);
280 fscache_run_op(object, op);
281 }
282 ret = 0;
283 } else if (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
284 op->object = object;
285 object->n_ops++;
286 atomic_inc(&op->usage);
287 list_add_tail(&op->pend_link, &object->pending_ops);
288 fscache_stat(&fscache_n_op_pend);
289 ret = 0;
290 } else if (flags & BIT(FSCACHE_OBJECT_KILLED_BY_CACHE)) {
291 op->cancel(op);
292 op->state = FSCACHE_OP_ST_CANCELLED;
293 ret = -ENOBUFS;
294 } else {
295 fscache_report_unexpected_submission(object, op, ostate);
296 ASSERT(!fscache_object_is_active(object));
297 op->cancel(op);
298 op->state = FSCACHE_OP_ST_CANCELLED;
299 ret = -ENOBUFS;
300 }
301
302 spin_unlock(&object->lock);
303 return ret;
304 }
305
306 /*
307 * queue an object for withdrawal on error, aborting all following asynchronous
308 * operations
309 */
fscache_abort_object(struct fscache_object * object)310 void fscache_abort_object(struct fscache_object *object)
311 {
312 _enter("{OBJ%x}", object->debug_id);
313
314 fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR);
315 }
316
317 /*
318 * Jump start the operation processing on an object. The caller must hold
319 * object->lock.
320 */
fscache_start_operations(struct fscache_object * object)321 void fscache_start_operations(struct fscache_object *object)
322 {
323 struct fscache_operation *op;
324 bool stop = false;
325
326 while (!list_empty(&object->pending_ops) && !stop) {
327 op = list_entry(object->pending_ops.next,
328 struct fscache_operation, pend_link);
329
330 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
331 if (object->n_in_progress > 0)
332 break;
333 stop = true;
334 }
335 list_del_init(&op->pend_link);
336 fscache_run_op(object, op);
337
338 /* the pending queue was holding a ref on the object */
339 fscache_put_operation(op);
340 }
341
342 ASSERTCMP(object->n_in_progress, <=, object->n_ops);
343
344 _debug("woke %d ops on OBJ%x",
345 object->n_in_progress, object->debug_id);
346 }
347
348 /*
349 * cancel an operation that's pending on an object
350 */
fscache_cancel_op(struct fscache_operation * op,bool cancel_in_progress_op)351 int fscache_cancel_op(struct fscache_operation *op,
352 bool cancel_in_progress_op)
353 {
354 struct fscache_object *object = op->object;
355 bool put = false;
356 int ret;
357
358 _enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id);
359
360 ASSERTCMP(op->state, >=, FSCACHE_OP_ST_PENDING);
361 ASSERTCMP(op->state, !=, FSCACHE_OP_ST_CANCELLED);
362 ASSERTCMP(atomic_read(&op->usage), >, 0);
363
364 spin_lock(&object->lock);
365
366 ret = -EBUSY;
367 if (op->state == FSCACHE_OP_ST_PENDING) {
368 ASSERT(!list_empty(&op->pend_link));
369 list_del_init(&op->pend_link);
370 put = true;
371
372 fscache_stat(&fscache_n_op_cancelled);
373 op->cancel(op);
374 op->state = FSCACHE_OP_ST_CANCELLED;
375 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
376 object->n_exclusive--;
377 if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
378 wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
379 ret = 0;
380 } else if (op->state == FSCACHE_OP_ST_IN_PROGRESS && cancel_in_progress_op) {
381 ASSERTCMP(object->n_in_progress, >, 0);
382 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
383 object->n_exclusive--;
384 object->n_in_progress--;
385 if (object->n_in_progress == 0)
386 fscache_start_operations(object);
387
388 fscache_stat(&fscache_n_op_cancelled);
389 op->cancel(op);
390 op->state = FSCACHE_OP_ST_CANCELLED;
391 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
392 object->n_exclusive--;
393 if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
394 wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
395 ret = 0;
396 }
397
398 if (put)
399 fscache_put_operation(op);
400 spin_unlock(&object->lock);
401 _leave(" = %d", ret);
402 return ret;
403 }
404
405 /*
406 * Cancel all pending operations on an object
407 */
fscache_cancel_all_ops(struct fscache_object * object)408 void fscache_cancel_all_ops(struct fscache_object *object)
409 {
410 struct fscache_operation *op;
411
412 _enter("OBJ%x", object->debug_id);
413
414 spin_lock(&object->lock);
415
416 while (!list_empty(&object->pending_ops)) {
417 op = list_entry(object->pending_ops.next,
418 struct fscache_operation, pend_link);
419 fscache_stat(&fscache_n_op_cancelled);
420 list_del_init(&op->pend_link);
421
422 ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);
423 op->cancel(op);
424 op->state = FSCACHE_OP_ST_CANCELLED;
425
426 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
427 object->n_exclusive--;
428 if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
429 wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
430 fscache_put_operation(op);
431 cond_resched_lock(&object->lock);
432 }
433
434 spin_unlock(&object->lock);
435 _leave("");
436 }
437
438 /*
439 * Record the completion or cancellation of an in-progress operation.
440 */
fscache_op_complete(struct fscache_operation * op,bool cancelled)441 void fscache_op_complete(struct fscache_operation *op, bool cancelled)
442 {
443 struct fscache_object *object = op->object;
444
445 _enter("OBJ%x", object->debug_id);
446
447 ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS);
448 ASSERTCMP(object->n_in_progress, >, 0);
449 ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags),
450 object->n_exclusive, >, 0);
451 ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags),
452 object->n_in_progress, ==, 1);
453
454 spin_lock(&object->lock);
455
456 if (!cancelled) {
457 op->state = FSCACHE_OP_ST_COMPLETE;
458 } else {
459 op->cancel(op);
460 op->state = FSCACHE_OP_ST_CANCELLED;
461 }
462
463 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
464 object->n_exclusive--;
465 object->n_in_progress--;
466 if (object->n_in_progress == 0)
467 fscache_start_operations(object);
468
469 spin_unlock(&object->lock);
470 _leave("");
471 }
472 EXPORT_SYMBOL(fscache_op_complete);
473
474 /*
475 * release an operation
476 * - queues pending ops if this is the last in-progress op
477 */
fscache_put_operation(struct fscache_operation * op)478 void fscache_put_operation(struct fscache_operation *op)
479 {
480 struct fscache_object *object;
481 struct fscache_cache *cache;
482
483 _enter("{OBJ%x OP%x,%d}",
484 op->object->debug_id, op->debug_id, atomic_read(&op->usage));
485
486 ASSERTCMP(atomic_read(&op->usage), >, 0);
487
488 if (!atomic_dec_and_test(&op->usage))
489 return;
490
491 _debug("PUT OP");
492 ASSERTIFCMP(op->state != FSCACHE_OP_ST_INITIALISED &&
493 op->state != FSCACHE_OP_ST_COMPLETE,
494 op->state, ==, FSCACHE_OP_ST_CANCELLED);
495
496 fscache_stat(&fscache_n_op_release);
497
498 if (op->release) {
499 op->release(op);
500 op->release = NULL;
501 }
502 op->state = FSCACHE_OP_ST_DEAD;
503
504 object = op->object;
505 if (likely(object)) {
506 if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags))
507 atomic_dec(&object->n_reads);
508 if (test_bit(FSCACHE_OP_UNUSE_COOKIE, &op->flags))
509 fscache_unuse_cookie(object);
510
511 /* now... we may get called with the object spinlock held, so we
512 * complete the cleanup here only if we can immediately acquire the
513 * lock, and defer it otherwise */
514 if (!spin_trylock(&object->lock)) {
515 _debug("defer put");
516 fscache_stat(&fscache_n_op_deferred_release);
517
518 cache = object->cache;
519 spin_lock(&cache->op_gc_list_lock);
520 list_add_tail(&op->pend_link, &cache->op_gc_list);
521 spin_unlock(&cache->op_gc_list_lock);
522 schedule_work(&cache->op_gc);
523 _leave(" [defer]");
524 return;
525 }
526
527 ASSERTCMP(object->n_ops, >, 0);
528 object->n_ops--;
529 if (object->n_ops == 0)
530 fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
531
532 spin_unlock(&object->lock);
533 }
534
535 kfree(op);
536 _leave(" [done]");
537 }
538 EXPORT_SYMBOL(fscache_put_operation);
539
540 /*
541 * garbage collect operations that have had their release deferred
542 */
fscache_operation_gc(struct work_struct * work)543 void fscache_operation_gc(struct work_struct *work)
544 {
545 struct fscache_operation *op;
546 struct fscache_object *object;
547 struct fscache_cache *cache =
548 container_of(work, struct fscache_cache, op_gc);
549 int count = 0;
550
551 _enter("");
552
553 do {
554 spin_lock(&cache->op_gc_list_lock);
555 if (list_empty(&cache->op_gc_list)) {
556 spin_unlock(&cache->op_gc_list_lock);
557 break;
558 }
559
560 op = list_entry(cache->op_gc_list.next,
561 struct fscache_operation, pend_link);
562 list_del(&op->pend_link);
563 spin_unlock(&cache->op_gc_list_lock);
564
565 object = op->object;
566 spin_lock(&object->lock);
567
568 _debug("GC DEFERRED REL OBJ%x OP%x",
569 object->debug_id, op->debug_id);
570 fscache_stat(&fscache_n_op_gc);
571
572 ASSERTCMP(atomic_read(&op->usage), ==, 0);
573 ASSERTCMP(op->state, ==, FSCACHE_OP_ST_DEAD);
574
575 ASSERTCMP(object->n_ops, >, 0);
576 object->n_ops--;
577 if (object->n_ops == 0)
578 fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
579
580 spin_unlock(&object->lock);
581 kfree(op);
582
583 } while (count++ < 20);
584
585 if (!list_empty(&cache->op_gc_list))
586 schedule_work(&cache->op_gc);
587
588 _leave("");
589 }
590
591 /*
592 * execute an operation using fs_op_wq to provide processing context -
593 * the caller holds a ref to this object, so we don't need to hold one
594 */
fscache_op_work_func(struct work_struct * work)595 void fscache_op_work_func(struct work_struct *work)
596 {
597 struct fscache_operation *op =
598 container_of(work, struct fscache_operation, work);
599 unsigned long start;
600
601 _enter("{OBJ%x OP%x,%d}",
602 op->object->debug_id, op->debug_id, atomic_read(&op->usage));
603
604 ASSERT(op->processor != NULL);
605 start = jiffies;
606 op->processor(op);
607 fscache_hist(fscache_ops_histogram, start);
608 fscache_put_operation(op);
609
610 _leave("");
611 }
612