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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 | ||
5753c441 | 36 | ASSERT(list_empty(&op->pend_link)); |
952efe7b DH |
37 | ASSERT(op->processor != NULL); |
38 | ASSERTCMP(op->object->state, >=, FSCACHE_OBJECT_AVAILABLE); | |
39 | ASSERTCMP(atomic_read(&op->usage), >, 0); | |
40 | ||
5753c441 DH |
41 | fscache_stat(&fscache_n_op_enqueue); |
42 | switch (op->flags & FSCACHE_OP_TYPE) { | |
8af7c124 TH |
43 | case FSCACHE_OP_ASYNC: |
44 | _debug("queue async"); | |
5753c441 | 45 | atomic_inc(&op->usage); |
8af7c124 | 46 | if (!queue_work(fscache_op_wq, &op->work)) |
5753c441 DH |
47 | fscache_put_operation(op); |
48 | break; | |
5753c441 DH |
49 | case FSCACHE_OP_MYTHREAD: |
50 | _debug("queue for caller's attention"); | |
51 | break; | |
52 | default: | |
53 | printk(KERN_ERR "FS-Cache: Unexpected op type %lx", | |
54 | op->flags); | |
55 | BUG(); | |
56 | break; | |
952efe7b DH |
57 | } |
58 | } | |
59 | EXPORT_SYMBOL(fscache_enqueue_operation); | |
60 | ||
61 | /* | |
62 | * start an op running | |
63 | */ | |
64 | static void fscache_run_op(struct fscache_object *object, | |
65 | struct fscache_operation *op) | |
66 | { | |
67 | object->n_in_progress++; | |
68 | if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags)) | |
69 | wake_up_bit(&op->flags, FSCACHE_OP_WAITING); | |
70 | if (op->processor) | |
71 | fscache_enqueue_operation(op); | |
72 | fscache_stat(&fscache_n_op_run); | |
73 | } | |
74 | ||
75 | /* | |
76 | * submit an exclusive operation for an object | |
77 | * - other ops are excluded from running simultaneously with this one | |
78 | * - this gets any extra refs it needs on an op | |
79 | */ | |
80 | int fscache_submit_exclusive_op(struct fscache_object *object, | |
81 | struct fscache_operation *op) | |
82 | { | |
83 | int ret; | |
84 | ||
85 | _enter("{OBJ%x OP%x},", object->debug_id, op->debug_id); | |
86 | ||
87 | spin_lock(&object->lock); | |
88 | ASSERTCMP(object->n_ops, >=, object->n_in_progress); | |
89 | ASSERTCMP(object->n_ops, >=, object->n_exclusive); | |
5753c441 | 90 | ASSERT(list_empty(&op->pend_link)); |
952efe7b DH |
91 | |
92 | ret = -ENOBUFS; | |
93 | if (fscache_object_is_active(object)) { | |
94 | op->object = object; | |
95 | object->n_ops++; | |
96 | object->n_exclusive++; /* reads and writes must wait */ | |
97 | ||
ba28b93a | 98 | if (object->n_ops > 1) { |
952efe7b DH |
99 | atomic_inc(&op->usage); |
100 | list_add_tail(&op->pend_link, &object->pending_ops); | |
101 | fscache_stat(&fscache_n_op_pend); | |
102 | } else if (!list_empty(&object->pending_ops)) { | |
103 | atomic_inc(&op->usage); | |
104 | list_add_tail(&op->pend_link, &object->pending_ops); | |
105 | fscache_stat(&fscache_n_op_pend); | |
106 | fscache_start_operations(object); | |
107 | } else { | |
108 | ASSERTCMP(object->n_in_progress, ==, 0); | |
109 | fscache_run_op(object, op); | |
110 | } | |
111 | ||
112 | /* need to issue a new write op after this */ | |
113 | clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); | |
114 | ret = 0; | |
115 | } else if (object->state == FSCACHE_OBJECT_CREATING) { | |
116 | op->object = object; | |
117 | object->n_ops++; | |
118 | object->n_exclusive++; /* reads and writes must wait */ | |
119 | atomic_inc(&op->usage); | |
120 | list_add_tail(&op->pend_link, &object->pending_ops); | |
121 | fscache_stat(&fscache_n_op_pend); | |
122 | ret = 0; | |
123 | } else { | |
124 | /* not allowed to submit ops in any other state */ | |
125 | BUG(); | |
126 | } | |
127 | ||
128 | spin_unlock(&object->lock); | |
129 | return ret; | |
130 | } | |
131 | ||
132 | /* | |
133 | * report an unexpected submission | |
134 | */ | |
135 | static void fscache_report_unexpected_submission(struct fscache_object *object, | |
136 | struct fscache_operation *op, | |
137 | unsigned long ostate) | |
138 | { | |
139 | static bool once_only; | |
140 | struct fscache_operation *p; | |
141 | unsigned n; | |
142 | ||
143 | if (once_only) | |
144 | return; | |
145 | once_only = true; | |
146 | ||
147 | kdebug("unexpected submission OP%x [OBJ%x %s]", | |
148 | op->debug_id, object->debug_id, | |
149 | fscache_object_states[object->state]); | |
150 | kdebug("objstate=%s [%s]", | |
151 | fscache_object_states[object->state], | |
152 | fscache_object_states[ostate]); | |
153 | kdebug("objflags=%lx", object->flags); | |
154 | kdebug("objevent=%lx [%lx]", object->events, object->event_mask); | |
155 | kdebug("ops=%u inp=%u exc=%u", | |
156 | object->n_ops, object->n_in_progress, object->n_exclusive); | |
157 | ||
158 | if (!list_empty(&object->pending_ops)) { | |
159 | n = 0; | |
160 | list_for_each_entry(p, &object->pending_ops, pend_link) { | |
161 | ASSERTCMP(p->object, ==, object); | |
162 | kdebug("%p %p", op->processor, op->release); | |
163 | n++; | |
164 | } | |
165 | ||
166 | kdebug("n=%u", n); | |
167 | } | |
168 | ||
169 | dump_stack(); | |
170 | } | |
171 | ||
172 | /* | |
173 | * submit an operation for an object | |
174 | * - objects may be submitted only in the following states: | |
175 | * - during object creation (write ops may be submitted) | |
176 | * - whilst the object is active | |
177 | * - after an I/O error incurred in one of the two above states (op rejected) | |
178 | * - this gets any extra refs it needs on an op | |
179 | */ | |
180 | int fscache_submit_op(struct fscache_object *object, | |
181 | struct fscache_operation *op) | |
182 | { | |
183 | unsigned long ostate; | |
184 | int ret; | |
185 | ||
186 | _enter("{OBJ%x OP%x},{%u}", | |
187 | object->debug_id, op->debug_id, atomic_read(&op->usage)); | |
188 | ||
189 | ASSERTCMP(atomic_read(&op->usage), >, 0); | |
190 | ||
191 | spin_lock(&object->lock); | |
192 | ASSERTCMP(object->n_ops, >=, object->n_in_progress); | |
193 | ASSERTCMP(object->n_ops, >=, object->n_exclusive); | |
5753c441 | 194 | ASSERT(list_empty(&op->pend_link)); |
952efe7b DH |
195 | |
196 | ostate = object->state; | |
197 | smp_rmb(); | |
198 | ||
199 | if (fscache_object_is_active(object)) { | |
200 | op->object = object; | |
201 | object->n_ops++; | |
202 | ||
203 | if (object->n_exclusive > 0) { | |
204 | atomic_inc(&op->usage); | |
205 | list_add_tail(&op->pend_link, &object->pending_ops); | |
206 | fscache_stat(&fscache_n_op_pend); | |
207 | } else if (!list_empty(&object->pending_ops)) { | |
208 | atomic_inc(&op->usage); | |
209 | list_add_tail(&op->pend_link, &object->pending_ops); | |
210 | fscache_stat(&fscache_n_op_pend); | |
211 | fscache_start_operations(object); | |
212 | } else { | |
213 | ASSERTCMP(object->n_exclusive, ==, 0); | |
214 | fscache_run_op(object, op); | |
215 | } | |
216 | ret = 0; | |
217 | } else if (object->state == FSCACHE_OBJECT_CREATING) { | |
218 | op->object = object; | |
219 | object->n_ops++; | |
220 | atomic_inc(&op->usage); | |
221 | list_add_tail(&op->pend_link, &object->pending_ops); | |
222 | fscache_stat(&fscache_n_op_pend); | |
223 | ret = 0; | |
e3d4d28b DH |
224 | } else if (object->state == FSCACHE_OBJECT_DYING || |
225 | object->state == FSCACHE_OBJECT_LC_DYING || | |
226 | object->state == FSCACHE_OBJECT_WITHDRAWING) { | |
227 | fscache_stat(&fscache_n_op_rejected); | |
228 | ret = -ENOBUFS; | |
952efe7b DH |
229 | } else if (!test_bit(FSCACHE_IOERROR, &object->cache->flags)) { |
230 | fscache_report_unexpected_submission(object, op, ostate); | |
231 | ASSERT(!fscache_object_is_active(object)); | |
232 | ret = -ENOBUFS; | |
233 | } else { | |
234 | ret = -ENOBUFS; | |
235 | } | |
236 | ||
237 | spin_unlock(&object->lock); | |
238 | return ret; | |
239 | } | |
240 | ||
241 | /* | |
242 | * queue an object for withdrawal on error, aborting all following asynchronous | |
243 | * operations | |
244 | */ | |
245 | void fscache_abort_object(struct fscache_object *object) | |
246 | { | |
247 | _enter("{OBJ%x}", object->debug_id); | |
248 | ||
249 | fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR); | |
250 | } | |
251 | ||
252 | /* | |
253 | * jump start the operation processing on an object | |
254 | * - caller must hold object->lock | |
255 | */ | |
256 | void fscache_start_operations(struct fscache_object *object) | |
257 | { | |
258 | struct fscache_operation *op; | |
259 | bool stop = false; | |
260 | ||
261 | while (!list_empty(&object->pending_ops) && !stop) { | |
262 | op = list_entry(object->pending_ops.next, | |
263 | struct fscache_operation, pend_link); | |
264 | ||
265 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) { | |
266 | if (object->n_in_progress > 0) | |
267 | break; | |
268 | stop = true; | |
269 | } | |
270 | list_del_init(&op->pend_link); | |
5753c441 | 271 | fscache_run_op(object, op); |
952efe7b DH |
272 | |
273 | /* the pending queue was holding a ref on the object */ | |
274 | fscache_put_operation(op); | |
275 | } | |
276 | ||
277 | ASSERTCMP(object->n_in_progress, <=, object->n_ops); | |
278 | ||
279 | _debug("woke %d ops on OBJ%x", | |
280 | object->n_in_progress, object->debug_id); | |
281 | } | |
282 | ||
5753c441 DH |
283 | /* |
284 | * cancel an operation that's pending on an object | |
285 | */ | |
286 | int fscache_cancel_op(struct fscache_operation *op) | |
287 | { | |
288 | struct fscache_object *object = op->object; | |
289 | int ret; | |
290 | ||
291 | _enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id); | |
292 | ||
293 | spin_lock(&object->lock); | |
294 | ||
295 | ret = -EBUSY; | |
296 | if (!list_empty(&op->pend_link)) { | |
297 | fscache_stat(&fscache_n_op_cancelled); | |
298 | list_del_init(&op->pend_link); | |
299 | object->n_ops--; | |
300 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) | |
301 | object->n_exclusive--; | |
302 | if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags)) | |
303 | wake_up_bit(&op->flags, FSCACHE_OP_WAITING); | |
304 | fscache_put_operation(op); | |
305 | ret = 0; | |
306 | } | |
307 | ||
308 | spin_unlock(&object->lock); | |
309 | _leave(" = %d", ret); | |
310 | return ret; | |
311 | } | |
312 | ||
952efe7b DH |
313 | /* |
314 | * release an operation | |
315 | * - queues pending ops if this is the last in-progress op | |
316 | */ | |
317 | void fscache_put_operation(struct fscache_operation *op) | |
318 | { | |
319 | struct fscache_object *object; | |
320 | struct fscache_cache *cache; | |
321 | ||
322 | _enter("{OBJ%x OP%x,%d}", | |
323 | op->object->debug_id, op->debug_id, atomic_read(&op->usage)); | |
324 | ||
325 | ASSERTCMP(atomic_read(&op->usage), >, 0); | |
326 | ||
327 | if (!atomic_dec_and_test(&op->usage)) | |
328 | return; | |
329 | ||
330 | _debug("PUT OP"); | |
331 | if (test_and_set_bit(FSCACHE_OP_DEAD, &op->flags)) | |
332 | BUG(); | |
333 | ||
334 | fscache_stat(&fscache_n_op_release); | |
335 | ||
336 | if (op->release) { | |
337 | op->release(op); | |
338 | op->release = NULL; | |
339 | } | |
340 | ||
341 | object = op->object; | |
342 | ||
4fbf4291 DH |
343 | if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags)) |
344 | atomic_dec(&object->n_reads); | |
345 | ||
952efe7b DH |
346 | /* now... we may get called with the object spinlock held, so we |
347 | * complete the cleanup here only if we can immediately acquire the | |
348 | * lock, and defer it otherwise */ | |
349 | if (!spin_trylock(&object->lock)) { | |
350 | _debug("defer put"); | |
351 | fscache_stat(&fscache_n_op_deferred_release); | |
352 | ||
353 | cache = object->cache; | |
354 | spin_lock(&cache->op_gc_list_lock); | |
355 | list_add_tail(&op->pend_link, &cache->op_gc_list); | |
356 | spin_unlock(&cache->op_gc_list_lock); | |
357 | schedule_work(&cache->op_gc); | |
358 | _leave(" [defer]"); | |
359 | return; | |
360 | } | |
361 | ||
362 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) { | |
363 | ASSERTCMP(object->n_exclusive, >, 0); | |
364 | object->n_exclusive--; | |
365 | } | |
366 | ||
367 | ASSERTCMP(object->n_in_progress, >, 0); | |
368 | object->n_in_progress--; | |
369 | if (object->n_in_progress == 0) | |
370 | fscache_start_operations(object); | |
371 | ||
372 | ASSERTCMP(object->n_ops, >, 0); | |
373 | object->n_ops--; | |
374 | if (object->n_ops == 0) | |
375 | fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED); | |
376 | ||
377 | spin_unlock(&object->lock); | |
378 | ||
379 | kfree(op); | |
380 | _leave(" [done]"); | |
381 | } | |
382 | EXPORT_SYMBOL(fscache_put_operation); | |
383 | ||
384 | /* | |
385 | * garbage collect operations that have had their release deferred | |
386 | */ | |
387 | void fscache_operation_gc(struct work_struct *work) | |
388 | { | |
389 | struct fscache_operation *op; | |
390 | struct fscache_object *object; | |
391 | struct fscache_cache *cache = | |
392 | container_of(work, struct fscache_cache, op_gc); | |
393 | int count = 0; | |
394 | ||
395 | _enter(""); | |
396 | ||
397 | do { | |
398 | spin_lock(&cache->op_gc_list_lock); | |
399 | if (list_empty(&cache->op_gc_list)) { | |
400 | spin_unlock(&cache->op_gc_list_lock); | |
401 | break; | |
402 | } | |
403 | ||
404 | op = list_entry(cache->op_gc_list.next, | |
405 | struct fscache_operation, pend_link); | |
406 | list_del(&op->pend_link); | |
407 | spin_unlock(&cache->op_gc_list_lock); | |
408 | ||
409 | object = op->object; | |
410 | ||
411 | _debug("GC DEFERRED REL OBJ%x OP%x", | |
412 | object->debug_id, op->debug_id); | |
413 | fscache_stat(&fscache_n_op_gc); | |
414 | ||
415 | ASSERTCMP(atomic_read(&op->usage), ==, 0); | |
416 | ||
417 | spin_lock(&object->lock); | |
418 | if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) { | |
419 | ASSERTCMP(object->n_exclusive, >, 0); | |
420 | object->n_exclusive--; | |
421 | } | |
422 | ||
423 | ASSERTCMP(object->n_in_progress, >, 0); | |
424 | object->n_in_progress--; | |
425 | if (object->n_in_progress == 0) | |
426 | fscache_start_operations(object); | |
427 | ||
428 | ASSERTCMP(object->n_ops, >, 0); | |
429 | object->n_ops--; | |
430 | if (object->n_ops == 0) | |
431 | fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED); | |
432 | ||
433 | spin_unlock(&object->lock); | |
434 | ||
435 | } while (count++ < 20); | |
436 | ||
437 | if (!list_empty(&cache->op_gc_list)) | |
438 | schedule_work(&cache->op_gc); | |
439 | ||
440 | _leave(""); | |
441 | } | |
442 | ||
443 | /* | |
8af7c124 TH |
444 | * execute an operation using fs_op_wq to provide processing context - |
445 | * the caller holds a ref to this object, so we don't need to hold one | |
952efe7b | 446 | */ |
8af7c124 | 447 | void fscache_op_work_func(struct work_struct *work) |
952efe7b DH |
448 | { |
449 | struct fscache_operation *op = | |
8af7c124 | 450 | container_of(work, struct fscache_operation, work); |
952efe7b DH |
451 | unsigned long start; |
452 | ||
453 | _enter("{OBJ%x OP%x,%d}", | |
454 | op->object->debug_id, op->debug_id, atomic_read(&op->usage)); | |
455 | ||
456 | ASSERT(op->processor != NULL); | |
457 | start = jiffies; | |
458 | op->processor(op); | |
459 | fscache_hist(fscache_ops_histogram, start); | |
8af7c124 | 460 | fscache_put_operation(op); |
952efe7b DH |
461 | |
462 | _leave(""); | |
463 | } |