blob: 313e79a14266e69e2a47aafdffefc89b29f510df [file] [log] [blame]
David Howells952efe72009-04-03 16:42:39 +01001/* 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>
David Howells440f0af2009-11-19 18:11:01 +000016#include <linux/seq_file.h>
David Howells952efe72009-04-03 16:42:39 +010017#include "internal.h"
18
19atomic_t fscache_op_debug_id;
20EXPORT_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 */
30void 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
David Howells440f0af2009-11-19 18:11:01 +000035 fscache_set_op_state(op, "EnQ");
36
David Howells5753c442009-11-19 18:11:19 +000037 ASSERT(list_empty(&op->pend_link));
David Howells952efe72009-04-03 16:42:39 +010038 ASSERT(op->processor != NULL);
39 ASSERTCMP(op->object->state, >=, FSCACHE_OBJECT_AVAILABLE);
40 ASSERTCMP(atomic_read(&op->usage), >, 0);
41
David Howells5753c442009-11-19 18:11:19 +000042 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;
David Howells952efe72009-04-03 16:42:39 +010062 }
63}
64EXPORT_SYMBOL(fscache_enqueue_operation);
65
66/*
67 * start an op running
68 */
69static void fscache_run_op(struct fscache_object *object,
70 struct fscache_operation *op)
71{
David Howells440f0af2009-11-19 18:11:01 +000072 fscache_set_op_state(op, "Run");
73
David Howells952efe72009-04-03 16:42:39 +010074 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 */
87int 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
David Howells440f0af2009-11-19 18:11:01 +000094 fscache_set_op_state(op, "SubmitX");
95
David Howells952efe72009-04-03 16:42:39 +010096 spin_lock(&object->lock);
97 ASSERTCMP(object->n_ops, >=, object->n_in_progress);
98 ASSERTCMP(object->n_ops, >=, object->n_exclusive);
David Howells5753c442009-11-19 18:11:19 +000099 ASSERT(list_empty(&op->pend_link));
David Howells952efe72009-04-03 16:42:39 +0100100
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 */
144static 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 */
189int 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
David Howells440f0af2009-11-19 18:11:01 +0000200 fscache_set_op_state(op, "Submit");
201
David Howells952efe72009-04-03 16:42:39 +0100202 spin_lock(&object->lock);
203 ASSERTCMP(object->n_ops, >=, object->n_in_progress);
204 ASSERTCMP(object->n_ops, >=, object->n_exclusive);
David Howells5753c442009-11-19 18:11:19 +0000205 ASSERT(list_empty(&op->pend_link));
David Howells952efe72009-04-03 16:42:39 +0100206
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;
David Howellse3d4d282009-11-19 18:11:32 +0000235 } 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;
David Howells952efe72009-04-03 16:42:39 +0100240 } 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 */
256void 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 */
267void 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);
David Howells5753c442009-11-19 18:11:19 +0000282 fscache_run_op(object, op);
David Howells952efe72009-04-03 16:42:39 +0100283
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
294/*
David Howells5753c442009-11-19 18:11:19 +0000295 * cancel an operation that's pending on an object
296 */
297int 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
324/*
David Howells952efe72009-04-03 16:42:39 +0100325 * release an operation
326 * - queues pending ops if this is the last in-progress op
327 */
328void 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
David Howells440f0af2009-11-19 18:11:01 +0000341 fscache_set_op_state(op, "Put");
342
David Howells952efe72009-04-03 16:42:39 +0100343 _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
David Howells4fbf4292009-11-19 18:11:04 +0000356 if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags))
357 atomic_dec(&object->n_reads);
358
David Howells952efe72009-04-03 16:42:39 +0100359 /* 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}
395EXPORT_SYMBOL(fscache_put_operation);
396
397/*
398 * garbage collect operations that have had their release deferred
399 */
400void 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 */
459static 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 */
471static 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 */
483static 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
David Howells440f0af2009-11-19 18:11:01 +0000500/*
501 * describe an operation for slow-work debugging
502 */
503#ifdef CONFIG_SLOW_WORK_PROC
504static 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
David Howells952efe72009-04-03 16:42:39 +0100515const struct slow_work_ops fscache_op_slow_work_ops = {
David Howells3d7a6412009-11-19 18:10:23 +0000516 .owner = THIS_MODULE,
David Howells952efe72009-04-03 16:42:39 +0100517 .get_ref = fscache_op_get_ref,
518 .put_ref = fscache_op_put_ref,
519 .execute = fscache_op_execute,
David Howells440f0af2009-11-19 18:11:01 +0000520#ifdef CONFIG_SLOW_WORK_PROC
521 .desc = fscache_op_desc,
522#endif
David Howells952efe72009-04-03 16:42:39 +0100523};