1 /* FS-Cache worker operation management routines
3 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
11 * See Documentation/filesystems/caching/operations.txt
14 #define FSCACHE_DEBUG_LEVEL OPERATION
15 #include <linux/module.h>
16 #include <linux/seq_file.h>
17 #include <linux/slab.h>
20 atomic_t fscache_op_debug_id;
21 EXPORT_SYMBOL(fscache_op_debug_id);
24 * fscache_enqueue_operation - Enqueue an operation for processing
25 * @op: The operation to enqueue
27 * Enqueue an operation for processing by the FS-Cache thread pool.
29 * This will get its own ref on the object.
31 void fscache_enqueue_operation(struct fscache_operation *op)
33 _enter("{OBJ%x OP%x,%u}",
34 op->object->debug_id, op->debug_id, atomic_read(&op->usage));
36 ASSERT(list_empty(&op->pend_link));
37 ASSERT(op->processor != NULL);
38 ASSERT(fscache_object_is_available(op->object));
39 ASSERTCMP(atomic_read(&op->usage), >, 0);
40 ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS);
42 fscache_stat(&fscache_n_op_enqueue);
43 switch (op->flags & FSCACHE_OP_TYPE) {
44 case FSCACHE_OP_ASYNC:
45 _debug("queue async");
46 atomic_inc(&op->usage);
47 if (!queue_work(fscache_op_wq, &op->work))
48 fscache_put_operation(op);
50 case FSCACHE_OP_MYTHREAD:
51 _debug("queue for caller's attention");
54 pr_err("Unexpected op type %lx", op->flags);
59 EXPORT_SYMBOL(fscache_enqueue_operation);
64 static void fscache_run_op(struct fscache_object *object,
65 struct fscache_operation *op)
67 ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);
69 op->state = FSCACHE_OP_ST_IN_PROGRESS;
70 object->n_in_progress++;
71 if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
72 wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
74 fscache_enqueue_operation(op);
75 fscache_stat(&fscache_n_op_run);
79 * report an unexpected submission
81 static void fscache_report_unexpected_submission(struct fscache_object *object,
82 struct fscache_operation *op,
83 const struct fscache_state *ostate)
85 static bool once_only;
86 struct fscache_operation *p;
93 kdebug("unexpected submission OP%x [OBJ%x %s]",
94 op->debug_id, object->debug_id, object->state->name);
95 kdebug("objstate=%s [%s]", object->state->name, ostate->name);
96 kdebug("objflags=%lx", object->flags);
97 kdebug("objevent=%lx [%lx]", object->events, object->event_mask);
98 kdebug("ops=%u inp=%u exc=%u",
99 object->n_ops, object->n_in_progress, object->n_exclusive);
101 if (!list_empty(&object->pending_ops)) {
103 list_for_each_entry(p, &object->pending_ops, pend_link) {
104 ASSERTCMP(p->object, ==, object);
105 kdebug("%p %p", op->processor, op->release);
116 * submit an exclusive operation for an object
117 * - other ops are excluded from running simultaneously with this one
118 * - this gets any extra refs it needs on an op
120 int fscache_submit_exclusive_op(struct fscache_object *object,
121 struct fscache_operation *op)
123 const struct fscache_state *ostate;
127 _enter("{OBJ%x OP%x},", object->debug_id, op->debug_id);
129 ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
130 ASSERTCMP(atomic_read(&op->usage), >, 0);
132 spin_lock(&object->lock);
133 ASSERTCMP(object->n_ops, >=, object->n_in_progress);
134 ASSERTCMP(object->n_ops, >=, object->n_exclusive);
135 ASSERT(list_empty(&op->pend_link));
137 ostate = object->state;
140 op->state = FSCACHE_OP_ST_PENDING;
141 flags = READ_ONCE(object->flags);
142 if (unlikely(!(flags & BIT(FSCACHE_OBJECT_IS_LIVE)))) {
143 fscache_stat(&fscache_n_op_rejected);
144 op->state = FSCACHE_OP_ST_CANCELLED;
146 } else if (unlikely(fscache_cache_is_broken(object))) {
147 op->state = FSCACHE_OP_ST_CANCELLED;
149 } else if (flags & BIT(FSCACHE_OBJECT_IS_AVAILABLE)) {
152 object->n_exclusive++; /* reads and writes must wait */
154 if (object->n_in_progress > 0) {
155 atomic_inc(&op->usage);
156 list_add_tail(&op->pend_link, &object->pending_ops);
157 fscache_stat(&fscache_n_op_pend);
158 } else if (!list_empty(&object->pending_ops)) {
159 atomic_inc(&op->usage);
160 list_add_tail(&op->pend_link, &object->pending_ops);
161 fscache_stat(&fscache_n_op_pend);
162 fscache_start_operations(object);
164 ASSERTCMP(object->n_in_progress, ==, 0);
165 fscache_run_op(object, op);
168 /* need to issue a new write op after this */
169 clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
171 } else if (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
174 object->n_exclusive++; /* reads and writes must wait */
175 atomic_inc(&op->usage);
176 list_add_tail(&op->pend_link, &object->pending_ops);
177 fscache_stat(&fscache_n_op_pend);
179 } else if (flags & BIT(FSCACHE_OBJECT_KILLED_BY_CACHE)) {
180 op->state = FSCACHE_OP_ST_CANCELLED;
183 fscache_report_unexpected_submission(object, op, ostate);
184 op->state = FSCACHE_OP_ST_CANCELLED;
188 spin_unlock(&object->lock);
193 * submit an operation for an object
194 * - objects may be submitted only in the following states:
195 * - during object creation (write ops may be submitted)
196 * - whilst the object is active
197 * - after an I/O error incurred in one of the two above states (op rejected)
198 * - this gets any extra refs it needs on an op
200 int fscache_submit_op(struct fscache_object *object,
201 struct fscache_operation *op)
203 const struct fscache_state *ostate;
207 _enter("{OBJ%x OP%x},{%u}",
208 object->debug_id, op->debug_id, atomic_read(&op->usage));
210 ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
211 ASSERTCMP(atomic_read(&op->usage), >, 0);
213 spin_lock(&object->lock);
214 ASSERTCMP(object->n_ops, >=, object->n_in_progress);
215 ASSERTCMP(object->n_ops, >=, object->n_exclusive);
216 ASSERT(list_empty(&op->pend_link));
218 ostate = object->state;
221 op->state = FSCACHE_OP_ST_PENDING;
222 flags = READ_ONCE(object->flags);
223 if (unlikely(!(flags & BIT(FSCACHE_OBJECT_IS_LIVE)))) {
224 fscache_stat(&fscache_n_op_rejected);
225 op->state = FSCACHE_OP_ST_CANCELLED;
227 } else if (unlikely(fscache_cache_is_broken(object))) {
228 op->state = FSCACHE_OP_ST_CANCELLED;
230 } else if (flags & BIT(FSCACHE_OBJECT_IS_AVAILABLE)) {
234 if (object->n_exclusive > 0) {
235 atomic_inc(&op->usage);
236 list_add_tail(&op->pend_link, &object->pending_ops);
237 fscache_stat(&fscache_n_op_pend);
238 } else if (!list_empty(&object->pending_ops)) {
239 atomic_inc(&op->usage);
240 list_add_tail(&op->pend_link, &object->pending_ops);
241 fscache_stat(&fscache_n_op_pend);
242 fscache_start_operations(object);
244 ASSERTCMP(object->n_exclusive, ==, 0);
245 fscache_run_op(object, op);
248 } else if (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
251 atomic_inc(&op->usage);
252 list_add_tail(&op->pend_link, &object->pending_ops);
253 fscache_stat(&fscache_n_op_pend);
255 } else if (flags & BIT(FSCACHE_OBJECT_KILLED_BY_CACHE)) {
256 op->state = FSCACHE_OP_ST_CANCELLED;
259 fscache_report_unexpected_submission(object, op, ostate);
260 ASSERT(!fscache_object_is_active(object));
261 op->state = FSCACHE_OP_ST_CANCELLED;
265 spin_unlock(&object->lock);
270 * queue an object for withdrawal on error, aborting all following asynchronous
273 void fscache_abort_object(struct fscache_object *object)
275 _enter("{OBJ%x}", object->debug_id);
277 fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR);
281 * Jump start the operation processing on an object. The caller must hold
284 void fscache_start_operations(struct fscache_object *object)
286 struct fscache_operation *op;
289 while (!list_empty(&object->pending_ops) && !stop) {
290 op = list_entry(object->pending_ops.next,
291 struct fscache_operation, pend_link);
293 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
294 if (object->n_in_progress > 0)
298 list_del_init(&op->pend_link);
299 fscache_run_op(object, op);
301 /* the pending queue was holding a ref on the object */
302 fscache_put_operation(op);
305 ASSERTCMP(object->n_in_progress, <=, object->n_ops);
307 _debug("woke %d ops on OBJ%x",
308 object->n_in_progress, object->debug_id);
312 * cancel an operation that's pending on an object
314 int fscache_cancel_op(struct fscache_operation *op,
315 void (*do_cancel)(struct fscache_operation *),
316 bool cancel_in_progress_op)
318 struct fscache_object *object = op->object;
322 _enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id);
324 ASSERTCMP(op->state, >=, FSCACHE_OP_ST_PENDING);
325 ASSERTCMP(op->state, !=, FSCACHE_OP_ST_CANCELLED);
326 ASSERTCMP(atomic_read(&op->usage), >, 0);
328 spin_lock(&object->lock);
331 if (op->state == FSCACHE_OP_ST_PENDING) {
332 ASSERT(!list_empty(&op->pend_link));
333 list_del_init(&op->pend_link);
335 fscache_stat(&fscache_n_op_cancelled);
338 op->state = FSCACHE_OP_ST_CANCELLED;
339 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
340 object->n_exclusive--;
341 if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
342 wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
344 } else if (op->state == FSCACHE_OP_ST_IN_PROGRESS && cancel_in_progress_op) {
345 fscache_stat(&fscache_n_op_cancelled);
348 op->state = FSCACHE_OP_ST_CANCELLED;
349 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
350 object->n_exclusive--;
351 if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
352 wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
357 fscache_put_operation(op);
358 spin_unlock(&object->lock);
359 _leave(" = %d", ret);
364 * Cancel all pending operations on an object
366 void fscache_cancel_all_ops(struct fscache_object *object)
368 struct fscache_operation *op;
370 _enter("OBJ%x", object->debug_id);
372 spin_lock(&object->lock);
374 while (!list_empty(&object->pending_ops)) {
375 op = list_entry(object->pending_ops.next,
376 struct fscache_operation, pend_link);
377 fscache_stat(&fscache_n_op_cancelled);
378 list_del_init(&op->pend_link);
380 ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);
381 op->state = FSCACHE_OP_ST_CANCELLED;
383 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
384 object->n_exclusive--;
385 if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
386 wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
387 fscache_put_operation(op);
388 cond_resched_lock(&object->lock);
391 spin_unlock(&object->lock);
396 * Record the completion or cancellation of an in-progress operation.
398 void fscache_op_complete(struct fscache_operation *op, bool cancelled)
400 struct fscache_object *object = op->object;
402 _enter("OBJ%x", object->debug_id);
404 ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS);
405 ASSERTCMP(object->n_in_progress, >, 0);
406 ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags),
407 object->n_exclusive, >, 0);
408 ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags),
409 object->n_in_progress, ==, 1);
411 spin_lock(&object->lock);
413 op->state = cancelled ?
414 FSCACHE_OP_ST_CANCELLED : FSCACHE_OP_ST_COMPLETE;
416 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
417 object->n_exclusive--;
418 object->n_in_progress--;
419 if (object->n_in_progress == 0)
420 fscache_start_operations(object);
422 spin_unlock(&object->lock);
425 EXPORT_SYMBOL(fscache_op_complete);
428 * release an operation
429 * - queues pending ops if this is the last in-progress op
431 void fscache_put_operation(struct fscache_operation *op)
433 struct fscache_object *object;
434 struct fscache_cache *cache;
436 _enter("{OBJ%x OP%x,%d}",
437 op->object->debug_id, op->debug_id, atomic_read(&op->usage));
439 ASSERTCMP(atomic_read(&op->usage), >, 0);
441 if (!atomic_dec_and_test(&op->usage))
445 ASSERTIFCMP(op->state != FSCACHE_OP_ST_COMPLETE,
446 op->state, ==, FSCACHE_OP_ST_CANCELLED);
447 op->state = FSCACHE_OP_ST_DEAD;
449 fscache_stat(&fscache_n_op_release);
458 if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags))
459 atomic_dec(&object->n_reads);
460 if (test_bit(FSCACHE_OP_UNUSE_COOKIE, &op->flags))
461 fscache_unuse_cookie(object);
463 /* now... we may get called with the object spinlock held, so we
464 * complete the cleanup here only if we can immediately acquire the
465 * lock, and defer it otherwise */
466 if (!spin_trylock(&object->lock)) {
468 fscache_stat(&fscache_n_op_deferred_release);
470 cache = object->cache;
471 spin_lock(&cache->op_gc_list_lock);
472 list_add_tail(&op->pend_link, &cache->op_gc_list);
473 spin_unlock(&cache->op_gc_list_lock);
474 schedule_work(&cache->op_gc);
479 ASSERTCMP(object->n_ops, >, 0);
481 if (object->n_ops == 0)
482 fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
484 spin_unlock(&object->lock);
489 EXPORT_SYMBOL(fscache_put_operation);
492 * garbage collect operations that have had their release deferred
494 void fscache_operation_gc(struct work_struct *work)
496 struct fscache_operation *op;
497 struct fscache_object *object;
498 struct fscache_cache *cache =
499 container_of(work, struct fscache_cache, op_gc);
505 spin_lock(&cache->op_gc_list_lock);
506 if (list_empty(&cache->op_gc_list)) {
507 spin_unlock(&cache->op_gc_list_lock);
511 op = list_entry(cache->op_gc_list.next,
512 struct fscache_operation, pend_link);
513 list_del(&op->pend_link);
514 spin_unlock(&cache->op_gc_list_lock);
517 spin_lock(&object->lock);
519 _debug("GC DEFERRED REL OBJ%x OP%x",
520 object->debug_id, op->debug_id);
521 fscache_stat(&fscache_n_op_gc);
523 ASSERTCMP(atomic_read(&op->usage), ==, 0);
524 ASSERTCMP(op->state, ==, FSCACHE_OP_ST_DEAD);
526 ASSERTCMP(object->n_ops, >, 0);
528 if (object->n_ops == 0)
529 fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
531 spin_unlock(&object->lock);
534 } while (count++ < 20);
536 if (!list_empty(&cache->op_gc_list))
537 schedule_work(&cache->op_gc);
543 * execute an operation using fs_op_wq to provide processing context -
544 * the caller holds a ref to this object, so we don't need to hold one
546 void fscache_op_work_func(struct work_struct *work)
548 struct fscache_operation *op =
549 container_of(work, struct fscache_operation, work);
552 _enter("{OBJ%x OP%x,%d}",
553 op->object->debug_id, op->debug_id, atomic_read(&op->usage));
555 ASSERT(op->processor != NULL);
558 fscache_hist(fscache_ops_histogram, start);
559 fscache_put_operation(op);