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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) { | |
8af7c124 TH |
45 | case FSCACHE_OP_ASYNC: |
46 | _debug("queue async"); | |
5753c441 | 47 | atomic_inc(&op->usage); |
8af7c124 | 48 | if (!queue_work(fscache_op_wq, &op->work)) |
5753c441 DH |
49 | fscache_put_operation(op); |
50 | break; | |
5753c441 DH |
51 | case FSCACHE_OP_MYTHREAD: |
52 | _debug("queue for caller's attention"); | |
53 | break; | |
54 | default: | |
55 | printk(KERN_ERR "FS-Cache: Unexpected op type %lx", | |
56 | op->flags); | |
57 | BUG(); | |
58 | break; | |
952efe7b DH |
59 | } |
60 | } | |
61 | EXPORT_SYMBOL(fscache_enqueue_operation); | |
62 | ||
63 | /* | |
64 | * start an op running | |
65 | */ | |
66 | static void fscache_run_op(struct fscache_object *object, | |
67 | struct fscache_operation *op) | |
68 | { | |
440f0aff DH |
69 | fscache_set_op_state(op, "Run"); |
70 | ||
952efe7b DH |
71 | object->n_in_progress++; |
72 | if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags)) | |
73 | wake_up_bit(&op->flags, FSCACHE_OP_WAITING); | |
74 | if (op->processor) | |
75 | fscache_enqueue_operation(op); | |
76 | fscache_stat(&fscache_n_op_run); | |
77 | } | |
78 | ||
79 | /* | |
80 | * submit an exclusive operation for an object | |
81 | * - other ops are excluded from running simultaneously with this one | |
82 | * - this gets any extra refs it needs on an op | |
83 | */ | |
84 | int fscache_submit_exclusive_op(struct fscache_object *object, | |
85 | struct fscache_operation *op) | |
86 | { | |
87 | int ret; | |
88 | ||
89 | _enter("{OBJ%x OP%x},", object->debug_id, op->debug_id); | |
90 | ||
440f0aff DH |
91 | fscache_set_op_state(op, "SubmitX"); |
92 | ||
952efe7b DH |
93 | spin_lock(&object->lock); |
94 | ASSERTCMP(object->n_ops, >=, object->n_in_progress); | |
95 | ASSERTCMP(object->n_ops, >=, object->n_exclusive); | |
5753c441 | 96 | ASSERT(list_empty(&op->pend_link)); |
952efe7b DH |
97 | |
98 | ret = -ENOBUFS; | |
99 | if (fscache_object_is_active(object)) { | |
100 | op->object = object; | |
101 | object->n_ops++; | |
102 | object->n_exclusive++; /* reads and writes must wait */ | |
103 | ||
104 | if (object->n_ops > 0) { | |
105 | atomic_inc(&op->usage); | |
106 | list_add_tail(&op->pend_link, &object->pending_ops); | |
107 | fscache_stat(&fscache_n_op_pend); | |
108 | } else if (!list_empty(&object->pending_ops)) { | |
109 | atomic_inc(&op->usage); | |
110 | list_add_tail(&op->pend_link, &object->pending_ops); | |
111 | fscache_stat(&fscache_n_op_pend); | |
112 | fscache_start_operations(object); | |
113 | } else { | |
114 | ASSERTCMP(object->n_in_progress, ==, 0); | |
115 | fscache_run_op(object, op); | |
116 | } | |
117 | ||
118 | /* need to issue a new write op after this */ | |
119 | clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); | |
120 | ret = 0; | |
121 | } else if (object->state == FSCACHE_OBJECT_CREATING) { | |
122 | op->object = object; | |
123 | object->n_ops++; | |
124 | object->n_exclusive++; /* reads and writes must wait */ | |
125 | atomic_inc(&op->usage); | |
126 | list_add_tail(&op->pend_link, &object->pending_ops); | |
127 | fscache_stat(&fscache_n_op_pend); | |
128 | ret = 0; | |
129 | } else { | |
130 | /* not allowed to submit ops in any other state */ | |
131 | BUG(); | |
132 | } | |
133 | ||
134 | spin_unlock(&object->lock); | |
135 | return ret; | |
136 | } | |
137 | ||
138 | /* | |
139 | * report an unexpected submission | |
140 | */ | |
141 | static void fscache_report_unexpected_submission(struct fscache_object *object, | |
142 | struct fscache_operation *op, | |
143 | unsigned long ostate) | |
144 | { | |
145 | static bool once_only; | |
146 | struct fscache_operation *p; | |
147 | unsigned n; | |
148 | ||
149 | if (once_only) | |
150 | return; | |
151 | once_only = true; | |
152 | ||
153 | kdebug("unexpected submission OP%x [OBJ%x %s]", | |
154 | op->debug_id, object->debug_id, | |
155 | fscache_object_states[object->state]); | |
156 | kdebug("objstate=%s [%s]", | |
157 | fscache_object_states[object->state], | |
158 | fscache_object_states[ostate]); | |
159 | kdebug("objflags=%lx", object->flags); | |
160 | kdebug("objevent=%lx [%lx]", object->events, object->event_mask); | |
161 | kdebug("ops=%u inp=%u exc=%u", | |
162 | object->n_ops, object->n_in_progress, object->n_exclusive); | |
163 | ||
164 | if (!list_empty(&object->pending_ops)) { | |
165 | n = 0; | |
166 | list_for_each_entry(p, &object->pending_ops, pend_link) { | |
167 | ASSERTCMP(p->object, ==, object); | |
168 | kdebug("%p %p", op->processor, op->release); | |
169 | n++; | |
170 | } | |
171 | ||
172 | kdebug("n=%u", n); | |
173 | } | |
174 | ||
175 | dump_stack(); | |
176 | } | |
177 | ||
178 | /* | |
179 | * submit an operation for an object | |
180 | * - objects may be submitted only in the following states: | |
181 | * - during object creation (write ops may be submitted) | |
182 | * - whilst the object is active | |
183 | * - after an I/O error incurred in one of the two above states (op rejected) | |
184 | * - this gets any extra refs it needs on an op | |
185 | */ | |
186 | int fscache_submit_op(struct fscache_object *object, | |
187 | struct fscache_operation *op) | |
188 | { | |
189 | unsigned long ostate; | |
190 | int ret; | |
191 | ||
192 | _enter("{OBJ%x OP%x},{%u}", | |
193 | object->debug_id, op->debug_id, atomic_read(&op->usage)); | |
194 | ||
195 | ASSERTCMP(atomic_read(&op->usage), >, 0); | |
196 | ||
440f0aff DH |
197 | fscache_set_op_state(op, "Submit"); |
198 | ||
952efe7b DH |
199 | spin_lock(&object->lock); |
200 | ASSERTCMP(object->n_ops, >=, object->n_in_progress); | |
201 | ASSERTCMP(object->n_ops, >=, object->n_exclusive); | |
5753c441 | 202 | ASSERT(list_empty(&op->pend_link)); |
952efe7b DH |
203 | |
204 | ostate = object->state; | |
205 | smp_rmb(); | |
206 | ||
207 | if (fscache_object_is_active(object)) { | |
208 | op->object = object; | |
209 | object->n_ops++; | |
210 | ||
211 | if (object->n_exclusive > 0) { | |
212 | atomic_inc(&op->usage); | |
213 | list_add_tail(&op->pend_link, &object->pending_ops); | |
214 | fscache_stat(&fscache_n_op_pend); | |
215 | } else if (!list_empty(&object->pending_ops)) { | |
216 | atomic_inc(&op->usage); | |
217 | list_add_tail(&op->pend_link, &object->pending_ops); | |
218 | fscache_stat(&fscache_n_op_pend); | |
219 | fscache_start_operations(object); | |
220 | } else { | |
221 | ASSERTCMP(object->n_exclusive, ==, 0); | |
222 | fscache_run_op(object, op); | |
223 | } | |
224 | ret = 0; | |
225 | } else if (object->state == FSCACHE_OBJECT_CREATING) { | |
226 | op->object = object; | |
227 | object->n_ops++; | |
228 | atomic_inc(&op->usage); | |
229 | list_add_tail(&op->pend_link, &object->pending_ops); | |
230 | fscache_stat(&fscache_n_op_pend); | |
231 | ret = 0; | |
e3d4d28b DH |
232 | } else if (object->state == FSCACHE_OBJECT_DYING || |
233 | object->state == FSCACHE_OBJECT_LC_DYING || | |
234 | object->state == FSCACHE_OBJECT_WITHDRAWING) { | |
235 | fscache_stat(&fscache_n_op_rejected); | |
236 | ret = -ENOBUFS; | |
952efe7b DH |
237 | } else if (!test_bit(FSCACHE_IOERROR, &object->cache->flags)) { |
238 | fscache_report_unexpected_submission(object, op, ostate); | |
239 | ASSERT(!fscache_object_is_active(object)); | |
240 | ret = -ENOBUFS; | |
241 | } else { | |
242 | ret = -ENOBUFS; | |
243 | } | |
244 | ||
245 | spin_unlock(&object->lock); | |
246 | return ret; | |
247 | } | |
248 | ||
249 | /* | |
250 | * queue an object for withdrawal on error, aborting all following asynchronous | |
251 | * operations | |
252 | */ | |
253 | void fscache_abort_object(struct fscache_object *object) | |
254 | { | |
255 | _enter("{OBJ%x}", object->debug_id); | |
256 | ||
257 | fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR); | |
258 | } | |
259 | ||
260 | /* | |
261 | * jump start the operation processing on an object | |
262 | * - caller must hold object->lock | |
263 | */ | |
264 | void fscache_start_operations(struct fscache_object *object) | |
265 | { | |
266 | struct fscache_operation *op; | |
267 | bool stop = false; | |
268 | ||
269 | while (!list_empty(&object->pending_ops) && !stop) { | |
270 | op = list_entry(object->pending_ops.next, | |
271 | struct fscache_operation, pend_link); | |
272 | ||
273 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) { | |
274 | if (object->n_in_progress > 0) | |
275 | break; | |
276 | stop = true; | |
277 | } | |
278 | list_del_init(&op->pend_link); | |
5753c441 | 279 | fscache_run_op(object, op); |
952efe7b DH |
280 | |
281 | /* the pending queue was holding a ref on the object */ | |
282 | fscache_put_operation(op); | |
283 | } | |
284 | ||
285 | ASSERTCMP(object->n_in_progress, <=, object->n_ops); | |
286 | ||
287 | _debug("woke %d ops on OBJ%x", | |
288 | object->n_in_progress, object->debug_id); | |
289 | } | |
290 | ||
5753c441 DH |
291 | /* |
292 | * cancel an operation that's pending on an object | |
293 | */ | |
294 | int fscache_cancel_op(struct fscache_operation *op) | |
295 | { | |
296 | struct fscache_object *object = op->object; | |
297 | int ret; | |
298 | ||
299 | _enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id); | |
300 | ||
301 | spin_lock(&object->lock); | |
302 | ||
303 | ret = -EBUSY; | |
304 | if (!list_empty(&op->pend_link)) { | |
305 | fscache_stat(&fscache_n_op_cancelled); | |
306 | list_del_init(&op->pend_link); | |
307 | object->n_ops--; | |
308 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) | |
309 | object->n_exclusive--; | |
310 | if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags)) | |
311 | wake_up_bit(&op->flags, FSCACHE_OP_WAITING); | |
312 | fscache_put_operation(op); | |
313 | ret = 0; | |
314 | } | |
315 | ||
316 | spin_unlock(&object->lock); | |
317 | _leave(" = %d", ret); | |
318 | return ret; | |
319 | } | |
320 | ||
952efe7b DH |
321 | /* |
322 | * release an operation | |
323 | * - queues pending ops if this is the last in-progress op | |
324 | */ | |
325 | void fscache_put_operation(struct fscache_operation *op) | |
326 | { | |
327 | struct fscache_object *object; | |
328 | struct fscache_cache *cache; | |
329 | ||
330 | _enter("{OBJ%x OP%x,%d}", | |
331 | op->object->debug_id, op->debug_id, atomic_read(&op->usage)); | |
332 | ||
333 | ASSERTCMP(atomic_read(&op->usage), >, 0); | |
334 | ||
335 | if (!atomic_dec_and_test(&op->usage)) | |
336 | return; | |
337 | ||
440f0aff DH |
338 | fscache_set_op_state(op, "Put"); |
339 | ||
952efe7b DH |
340 | _debug("PUT OP"); |
341 | if (test_and_set_bit(FSCACHE_OP_DEAD, &op->flags)) | |
342 | BUG(); | |
343 | ||
344 | fscache_stat(&fscache_n_op_release); | |
345 | ||
346 | if (op->release) { | |
347 | op->release(op); | |
348 | op->release = NULL; | |
349 | } | |
350 | ||
351 | object = op->object; | |
352 | ||
4fbf4291 DH |
353 | if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags)) |
354 | atomic_dec(&object->n_reads); | |
355 | ||
952efe7b DH |
356 | /* now... we may get called with the object spinlock held, so we |
357 | * complete the cleanup here only if we can immediately acquire the | |
358 | * lock, and defer it otherwise */ | |
359 | if (!spin_trylock(&object->lock)) { | |
360 | _debug("defer put"); | |
361 | fscache_stat(&fscache_n_op_deferred_release); | |
362 | ||
363 | cache = object->cache; | |
364 | spin_lock(&cache->op_gc_list_lock); | |
365 | list_add_tail(&op->pend_link, &cache->op_gc_list); | |
366 | spin_unlock(&cache->op_gc_list_lock); | |
367 | schedule_work(&cache->op_gc); | |
368 | _leave(" [defer]"); | |
369 | return; | |
370 | } | |
371 | ||
372 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) { | |
373 | ASSERTCMP(object->n_exclusive, >, 0); | |
374 | object->n_exclusive--; | |
375 | } | |
376 | ||
377 | ASSERTCMP(object->n_in_progress, >, 0); | |
378 | object->n_in_progress--; | |
379 | if (object->n_in_progress == 0) | |
380 | fscache_start_operations(object); | |
381 | ||
382 | ASSERTCMP(object->n_ops, >, 0); | |
383 | object->n_ops--; | |
384 | if (object->n_ops == 0) | |
385 | fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED); | |
386 | ||
387 | spin_unlock(&object->lock); | |
388 | ||
389 | kfree(op); | |
390 | _leave(" [done]"); | |
391 | } | |
392 | EXPORT_SYMBOL(fscache_put_operation); | |
393 | ||
394 | /* | |
395 | * garbage collect operations that have had their release deferred | |
396 | */ | |
397 | void fscache_operation_gc(struct work_struct *work) | |
398 | { | |
399 | struct fscache_operation *op; | |
400 | struct fscache_object *object; | |
401 | struct fscache_cache *cache = | |
402 | container_of(work, struct fscache_cache, op_gc); | |
403 | int count = 0; | |
404 | ||
405 | _enter(""); | |
406 | ||
407 | do { | |
408 | spin_lock(&cache->op_gc_list_lock); | |
409 | if (list_empty(&cache->op_gc_list)) { | |
410 | spin_unlock(&cache->op_gc_list_lock); | |
411 | break; | |
412 | } | |
413 | ||
414 | op = list_entry(cache->op_gc_list.next, | |
415 | struct fscache_operation, pend_link); | |
416 | list_del(&op->pend_link); | |
417 | spin_unlock(&cache->op_gc_list_lock); | |
418 | ||
419 | object = op->object; | |
420 | ||
421 | _debug("GC DEFERRED REL OBJ%x OP%x", | |
422 | object->debug_id, op->debug_id); | |
423 | fscache_stat(&fscache_n_op_gc); | |
424 | ||
425 | ASSERTCMP(atomic_read(&op->usage), ==, 0); | |
426 | ||
427 | spin_lock(&object->lock); | |
428 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) { | |
429 | ASSERTCMP(object->n_exclusive, >, 0); | |
430 | object->n_exclusive--; | |
431 | } | |
432 | ||
433 | ASSERTCMP(object->n_in_progress, >, 0); | |
434 | object->n_in_progress--; | |
435 | if (object->n_in_progress == 0) | |
436 | fscache_start_operations(object); | |
437 | ||
438 | ASSERTCMP(object->n_ops, >, 0); | |
439 | object->n_ops--; | |
440 | if (object->n_ops == 0) | |
441 | fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED); | |
442 | ||
443 | spin_unlock(&object->lock); | |
444 | ||
445 | } while (count++ < 20); | |
446 | ||
447 | if (!list_empty(&cache->op_gc_list)) | |
448 | schedule_work(&cache->op_gc); | |
449 | ||
450 | _leave(""); | |
451 | } | |
452 | ||
453 | /* | |
8af7c124 TH |
454 | * execute an operation using fs_op_wq to provide processing context - |
455 | * the caller holds a ref to this object, so we don't need to hold one | |
952efe7b | 456 | */ |
8af7c124 | 457 | void fscache_op_work_func(struct work_struct *work) |
952efe7b DH |
458 | { |
459 | struct fscache_operation *op = | |
8af7c124 | 460 | container_of(work, struct fscache_operation, work); |
952efe7b DH |
461 | unsigned long start; |
462 | ||
463 | _enter("{OBJ%x OP%x,%d}", | |
464 | op->object->debug_id, op->debug_id, atomic_read(&op->usage)); | |
465 | ||
466 | ASSERT(op->processor != NULL); | |
467 | start = jiffies; | |
468 | op->processor(op); | |
469 | fscache_hist(fscache_ops_histogram, start); | |
8af7c124 | 470 | fscache_put_operation(op); |
952efe7b DH |
471 | |
472 | _leave(""); | |
473 | } |