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>
19 atomic_t fscache_op_debug_id;
20 EXPORT_SYMBOL(fscache_op_debug_id);
23 * fscache_enqueue_operation - Enqueue an operation for processing
24 * @op: The operation to enqueue
26 * Enqueue an operation for processing by the FS-Cache thread pool.
28 * This will get its own ref on the object.
30 void fscache_enqueue_operation(struct fscache_operation *op)
32 _enter("{OBJ%x OP%x,%u}",
33 op->object->debug_id, op->debug_id, atomic_read(&op->usage));
35 fscache_set_op_state(op, "EnQ");
37 ASSERT(list_empty(&op->pend_link));
38 ASSERT(op->processor != NULL);
39 ASSERTCMP(op->object->state, >=, FSCACHE_OBJECT_AVAILABLE);
40 ASSERTCMP(atomic_read(&op->usage), >, 0);
42 fscache_stat(&fscache_n_op_enqueue);
43 switch (op->flags & FSCACHE_OP_TYPE) {
46 atomic_inc(&op->usage);
47 if (!schedule_work(&op->fast_work))
48 fscache_put_operation(op);
52 slow_work_enqueue(&op->slow_work);
54 case FSCACHE_OP_MYTHREAD:
55 _debug("queue for caller's attention");
58 printk(KERN_ERR "FS-Cache: Unexpected op type %lx",
64 EXPORT_SYMBOL(fscache_enqueue_operation);
69 static void fscache_run_op(struct fscache_object *object,
70 struct fscache_operation *op)
72 fscache_set_op_state(op, "Run");
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);
78 fscache_enqueue_operation(op);
79 fscache_stat(&fscache_n_op_run);
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
87 int fscache_submit_exclusive_op(struct fscache_object *object,
88 struct fscache_operation *op)
92 _enter("{OBJ%x OP%x},", object->debug_id, op->debug_id);
94 fscache_set_op_state(op, "SubmitX");
96 spin_lock(&object->lock);
97 ASSERTCMP(object->n_ops, >=, object->n_in_progress);
98 ASSERTCMP(object->n_ops, >=, object->n_exclusive);
99 ASSERT(list_empty(&op->pend_link));
102 if (fscache_object_is_active(object)) {
105 object->n_exclusive++; /* reads and writes must wait */
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);
117 ASSERTCMP(object->n_in_progress, ==, 0);
118 fscache_run_op(object, op);
121 /* need to issue a new write op after this */
122 clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
124 } else if (object->state == FSCACHE_OBJECT_CREATING) {
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);
133 /* not allowed to submit ops in any other state */
137 spin_unlock(&object->lock);
142 * report an unexpected submission
144 static void fscache_report_unexpected_submission(struct fscache_object *object,
145 struct fscache_operation *op,
146 unsigned long ostate)
148 static bool once_only;
149 struct fscache_operation *p;
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);
167 if (!list_empty(&object->pending_ops)) {
169 list_for_each_entry(p, &object->pending_ops, pend_link) {
170 ASSERTCMP(p->object, ==, object);
171 kdebug("%p %p", op->processor, op->release);
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
189 int fscache_submit_op(struct fscache_object *object,
190 struct fscache_operation *op)
192 unsigned long ostate;
195 _enter("{OBJ%x OP%x},{%u}",
196 object->debug_id, op->debug_id, atomic_read(&op->usage));
198 ASSERTCMP(atomic_read(&op->usage), >, 0);
200 fscache_set_op_state(op, "Submit");
202 spin_lock(&object->lock);
203 ASSERTCMP(object->n_ops, >=, object->n_in_progress);
204 ASSERTCMP(object->n_ops, >=, object->n_exclusive);
205 ASSERT(list_empty(&op->pend_link));
207 ostate = object->state;
210 if (fscache_object_is_active(object)) {
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);
224 ASSERTCMP(object->n_exclusive, ==, 0);
225 fscache_run_op(object, op);
228 } else if (object->state == FSCACHE_OBJECT_CREATING) {
231 atomic_inc(&op->usage);
232 list_add_tail(&op->pend_link, &object->pending_ops);
233 fscache_stat(&fscache_n_op_pend);
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);
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));
248 spin_unlock(&object->lock);
253 * queue an object for withdrawal on error, aborting all following asynchronous
256 void fscache_abort_object(struct fscache_object *object)
258 _enter("{OBJ%x}", object->debug_id);
260 fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR);
264 * jump start the operation processing on an object
265 * - caller must hold object->lock
267 void fscache_start_operations(struct fscache_object *object)
269 struct fscache_operation *op;
272 while (!list_empty(&object->pending_ops) && !stop) {
273 op = list_entry(object->pending_ops.next,
274 struct fscache_operation, pend_link);
276 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
277 if (object->n_in_progress > 0)
281 list_del_init(&op->pend_link);
282 fscache_run_op(object, op);
284 /* the pending queue was holding a ref on the object */
285 fscache_put_operation(op);
288 ASSERTCMP(object->n_in_progress, <=, object->n_ops);
290 _debug("woke %d ops on OBJ%x",
291 object->n_in_progress, object->debug_id);
295 * cancel an operation that's pending on an object
297 int fscache_cancel_op(struct fscache_operation *op)
299 struct fscache_object *object = op->object;
302 _enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id);
304 spin_lock(&object->lock);
307 if (!list_empty(&op->pend_link)) {
308 fscache_stat(&fscache_n_op_cancelled);
309 list_del_init(&op->pend_link);
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);
319 spin_unlock(&object->lock);
320 _leave(" = %d", ret);
325 * release an operation
326 * - queues pending ops if this is the last in-progress op
328 void fscache_put_operation(struct fscache_operation *op)
330 struct fscache_object *object;
331 struct fscache_cache *cache;
333 _enter("{OBJ%x OP%x,%d}",
334 op->object->debug_id, op->debug_id, atomic_read(&op->usage));
336 ASSERTCMP(atomic_read(&op->usage), >, 0);
338 if (!atomic_dec_and_test(&op->usage))
341 fscache_set_op_state(op, "Put");
344 if (test_and_set_bit(FSCACHE_OP_DEAD, &op->flags))
347 fscache_stat(&fscache_n_op_release);
356 if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags))
357 atomic_dec(&object->n_reads);
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)) {
364 fscache_stat(&fscache_n_op_deferred_release);
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);
375 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
376 ASSERTCMP(object->n_exclusive, >, 0);
377 object->n_exclusive--;
380 ASSERTCMP(object->n_in_progress, >, 0);
381 object->n_in_progress--;
382 if (object->n_in_progress == 0)
383 fscache_start_operations(object);
385 ASSERTCMP(object->n_ops, >, 0);
387 if (object->n_ops == 0)
388 fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
390 spin_unlock(&object->lock);
395 EXPORT_SYMBOL(fscache_put_operation);
398 * garbage collect operations that have had their release deferred
400 void fscache_operation_gc(struct work_struct *work)
402 struct fscache_operation *op;
403 struct fscache_object *object;
404 struct fscache_cache *cache =
405 container_of(work, struct fscache_cache, op_gc);
411 spin_lock(&cache->op_gc_list_lock);
412 if (list_empty(&cache->op_gc_list)) {
413 spin_unlock(&cache->op_gc_list_lock);
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);
424 _debug("GC DEFERRED REL OBJ%x OP%x",
425 object->debug_id, op->debug_id);
426 fscache_stat(&fscache_n_op_gc);
428 ASSERTCMP(atomic_read(&op->usage), ==, 0);
430 spin_lock(&object->lock);
431 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
432 ASSERTCMP(object->n_exclusive, >, 0);
433 object->n_exclusive--;
436 ASSERTCMP(object->n_in_progress, >, 0);
437 object->n_in_progress--;
438 if (object->n_in_progress == 0)
439 fscache_start_operations(object);
441 ASSERTCMP(object->n_ops, >, 0);
443 if (object->n_ops == 0)
444 fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
446 spin_unlock(&object->lock);
448 } while (count++ < 20);
450 if (!list_empty(&cache->op_gc_list))
451 schedule_work(&cache->op_gc);
457 * allow the slow work item processor to get a ref on an operation
459 static int fscache_op_get_ref(struct slow_work *work)
461 struct fscache_operation *op =
462 container_of(work, struct fscache_operation, slow_work);
464 atomic_inc(&op->usage);
469 * allow the slow work item processor to discard a ref on an operation
471 static void fscache_op_put_ref(struct slow_work *work)
473 struct fscache_operation *op =
474 container_of(work, struct fscache_operation, slow_work);
476 fscache_put_operation(op);
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
483 static void fscache_op_execute(struct slow_work *work)
485 struct fscache_operation *op =
486 container_of(work, struct fscache_operation, slow_work);
489 _enter("{OBJ%x OP%x,%d}",
490 op->object->debug_id, op->debug_id, atomic_read(&op->usage));
492 ASSERT(op->processor != NULL);
495 fscache_hist(fscache_ops_histogram, start);
501 * describe an operation for slow-work debugging
503 #ifdef CONFIG_SLOW_WORK_DEBUG
504 static void fscache_op_desc(struct slow_work *work, struct seq_file *m)
506 struct fscache_operation *op =
507 container_of(work, struct fscache_operation, slow_work);
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);
515 const struct slow_work_ops fscache_op_slow_work_ops = {
516 .owner = THIS_MODULE,
517 .get_ref = fscache_op_get_ref,
518 .put_ref = fscache_op_put_ref,
519 .execute = fscache_op_execute,
520 #ifdef CONFIG_SLOW_WORK_DEBUG
521 .desc = fscache_op_desc,