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b5108822 DH |
1 | /* Cache page management and data I/O routines |
2 | * | |
3 | * Copyright (C) 2004-2008 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 | ||
12 | #define FSCACHE_DEBUG_LEVEL PAGE | |
13 | #include <linux/module.h> | |
14 | #include <linux/fscache-cache.h> | |
15 | #include <linux/buffer_head.h> | |
16 | #include <linux/pagevec.h> | |
17 | #include "internal.h" | |
18 | ||
19 | /* | |
20 | * check to see if a page is being written to the cache | |
21 | */ | |
22 | bool __fscache_check_page_write(struct fscache_cookie *cookie, struct page *page) | |
23 | { | |
24 | void *val; | |
25 | ||
26 | rcu_read_lock(); | |
27 | val = radix_tree_lookup(&cookie->stores, page->index); | |
28 | rcu_read_unlock(); | |
29 | ||
30 | return val != NULL; | |
31 | } | |
32 | EXPORT_SYMBOL(__fscache_check_page_write); | |
33 | ||
34 | /* | |
35 | * wait for a page to finish being written to the cache | |
36 | */ | |
37 | void __fscache_wait_on_page_write(struct fscache_cookie *cookie, struct page *page) | |
38 | { | |
39 | wait_queue_head_t *wq = bit_waitqueue(&cookie->flags, 0); | |
40 | ||
41 | wait_event(*wq, !__fscache_check_page_write(cookie, page)); | |
42 | } | |
43 | EXPORT_SYMBOL(__fscache_wait_on_page_write); | |
44 | ||
45 | /* | |
46 | * note that a page has finished being written to the cache | |
47 | */ | |
48 | static void fscache_end_page_write(struct fscache_cookie *cookie, struct page *page) | |
49 | { | |
50 | struct page *xpage; | |
51 | ||
52 | spin_lock(&cookie->lock); | |
53 | xpage = radix_tree_delete(&cookie->stores, page->index); | |
54 | spin_unlock(&cookie->lock); | |
55 | ASSERT(xpage != NULL); | |
56 | ||
57 | wake_up_bit(&cookie->flags, 0); | |
58 | } | |
59 | ||
60 | /* | |
61 | * actually apply the changed attributes to a cache object | |
62 | */ | |
63 | static void fscache_attr_changed_op(struct fscache_operation *op) | |
64 | { | |
65 | struct fscache_object *object = op->object; | |
66 | ||
67 | _enter("{OBJ%x OP%x}", object->debug_id, op->debug_id); | |
68 | ||
69 | fscache_stat(&fscache_n_attr_changed_calls); | |
70 | ||
71 | if (fscache_object_is_active(object) && | |
72 | object->cache->ops->attr_changed(object) < 0) | |
73 | fscache_abort_object(object); | |
74 | ||
75 | _leave(""); | |
76 | } | |
77 | ||
78 | /* | |
79 | * notification that the attributes on an object have changed | |
80 | */ | |
81 | int __fscache_attr_changed(struct fscache_cookie *cookie) | |
82 | { | |
83 | struct fscache_operation *op; | |
84 | struct fscache_object *object; | |
85 | ||
86 | _enter("%p", cookie); | |
87 | ||
88 | ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); | |
89 | ||
90 | fscache_stat(&fscache_n_attr_changed); | |
91 | ||
92 | op = kzalloc(sizeof(*op), GFP_KERNEL); | |
93 | if (!op) { | |
94 | fscache_stat(&fscache_n_attr_changed_nomem); | |
95 | _leave(" = -ENOMEM"); | |
96 | return -ENOMEM; | |
97 | } | |
98 | ||
99 | fscache_operation_init(op, NULL); | |
100 | fscache_operation_init_slow(op, fscache_attr_changed_op); | |
101 | op->flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_EXCLUSIVE); | |
102 | ||
103 | spin_lock(&cookie->lock); | |
104 | ||
105 | if (hlist_empty(&cookie->backing_objects)) | |
106 | goto nobufs; | |
107 | object = hlist_entry(cookie->backing_objects.first, | |
108 | struct fscache_object, cookie_link); | |
109 | ||
110 | if (fscache_submit_exclusive_op(object, op) < 0) | |
111 | goto nobufs; | |
112 | spin_unlock(&cookie->lock); | |
113 | fscache_stat(&fscache_n_attr_changed_ok); | |
114 | fscache_put_operation(op); | |
115 | _leave(" = 0"); | |
116 | return 0; | |
117 | ||
118 | nobufs: | |
119 | spin_unlock(&cookie->lock); | |
120 | kfree(op); | |
121 | fscache_stat(&fscache_n_attr_changed_nobufs); | |
122 | _leave(" = %d", -ENOBUFS); | |
123 | return -ENOBUFS; | |
124 | } | |
125 | EXPORT_SYMBOL(__fscache_attr_changed); | |
126 | ||
127 | /* | |
128 | * handle secondary execution given to a retrieval op on behalf of the | |
129 | * cache | |
130 | */ | |
131 | static void fscache_retrieval_work(struct work_struct *work) | |
132 | { | |
133 | struct fscache_retrieval *op = | |
134 | container_of(work, struct fscache_retrieval, op.fast_work); | |
135 | unsigned long start; | |
136 | ||
137 | _enter("{OP%x}", op->op.debug_id); | |
138 | ||
139 | start = jiffies; | |
140 | op->op.processor(&op->op); | |
141 | fscache_hist(fscache_ops_histogram, start); | |
142 | fscache_put_operation(&op->op); | |
143 | } | |
144 | ||
145 | /* | |
146 | * release a retrieval op reference | |
147 | */ | |
148 | static void fscache_release_retrieval_op(struct fscache_operation *_op) | |
149 | { | |
150 | struct fscache_retrieval *op = | |
151 | container_of(_op, struct fscache_retrieval, op); | |
152 | ||
153 | _enter("{OP%x}", op->op.debug_id); | |
154 | ||
155 | fscache_hist(fscache_retrieval_histogram, op->start_time); | |
156 | if (op->context) | |
157 | fscache_put_context(op->op.object->cookie, op->context); | |
158 | ||
159 | _leave(""); | |
160 | } | |
161 | ||
162 | /* | |
163 | * allocate a retrieval op | |
164 | */ | |
165 | static struct fscache_retrieval *fscache_alloc_retrieval( | |
166 | struct address_space *mapping, | |
167 | fscache_rw_complete_t end_io_func, | |
168 | void *context) | |
169 | { | |
170 | struct fscache_retrieval *op; | |
171 | ||
172 | /* allocate a retrieval operation and attempt to submit it */ | |
173 | op = kzalloc(sizeof(*op), GFP_NOIO); | |
174 | if (!op) { | |
175 | fscache_stat(&fscache_n_retrievals_nomem); | |
176 | return NULL; | |
177 | } | |
178 | ||
179 | fscache_operation_init(&op->op, fscache_release_retrieval_op); | |
180 | op->op.flags = FSCACHE_OP_MYTHREAD | (1 << FSCACHE_OP_WAITING); | |
181 | op->mapping = mapping; | |
182 | op->end_io_func = end_io_func; | |
183 | op->context = context; | |
184 | op->start_time = jiffies; | |
185 | INIT_WORK(&op->op.fast_work, fscache_retrieval_work); | |
186 | INIT_LIST_HEAD(&op->to_do); | |
187 | return op; | |
188 | } | |
189 | ||
190 | /* | |
191 | * wait for a deferred lookup to complete | |
192 | */ | |
193 | static int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie) | |
194 | { | |
195 | unsigned long jif; | |
196 | ||
197 | _enter(""); | |
198 | ||
199 | if (!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)) { | |
200 | _leave(" = 0 [imm]"); | |
201 | return 0; | |
202 | } | |
203 | ||
204 | fscache_stat(&fscache_n_retrievals_wait); | |
205 | ||
206 | jif = jiffies; | |
207 | if (wait_on_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP, | |
208 | fscache_wait_bit_interruptible, | |
209 | TASK_INTERRUPTIBLE) != 0) { | |
210 | fscache_stat(&fscache_n_retrievals_intr); | |
211 | _leave(" = -ERESTARTSYS"); | |
212 | return -ERESTARTSYS; | |
213 | } | |
214 | ||
215 | ASSERT(!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)); | |
216 | ||
217 | smp_rmb(); | |
218 | fscache_hist(fscache_retrieval_delay_histogram, jif); | |
219 | _leave(" = 0 [dly]"); | |
220 | return 0; | |
221 | } | |
222 | ||
223 | /* | |
224 | * read a page from the cache or allocate a block in which to store it | |
225 | * - we return: | |
226 | * -ENOMEM - out of memory, nothing done | |
227 | * -ERESTARTSYS - interrupted | |
228 | * -ENOBUFS - no backing object available in which to cache the block | |
229 | * -ENODATA - no data available in the backing object for this block | |
230 | * 0 - dispatched a read - it'll call end_io_func() when finished | |
231 | */ | |
232 | int __fscache_read_or_alloc_page(struct fscache_cookie *cookie, | |
233 | struct page *page, | |
234 | fscache_rw_complete_t end_io_func, | |
235 | void *context, | |
236 | gfp_t gfp) | |
237 | { | |
238 | struct fscache_retrieval *op; | |
239 | struct fscache_object *object; | |
240 | int ret; | |
241 | ||
242 | _enter("%p,%p,,,", cookie, page); | |
243 | ||
244 | fscache_stat(&fscache_n_retrievals); | |
245 | ||
246 | if (hlist_empty(&cookie->backing_objects)) | |
247 | goto nobufs; | |
248 | ||
249 | ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); | |
250 | ASSERTCMP(page, !=, NULL); | |
251 | ||
252 | if (fscache_wait_for_deferred_lookup(cookie) < 0) | |
253 | return -ERESTARTSYS; | |
254 | ||
255 | op = fscache_alloc_retrieval(page->mapping, end_io_func, context); | |
256 | if (!op) { | |
257 | _leave(" = -ENOMEM"); | |
258 | return -ENOMEM; | |
259 | } | |
260 | ||
261 | spin_lock(&cookie->lock); | |
262 | ||
263 | if (hlist_empty(&cookie->backing_objects)) | |
264 | goto nobufs_unlock; | |
265 | object = hlist_entry(cookie->backing_objects.first, | |
266 | struct fscache_object, cookie_link); | |
267 | ||
268 | ASSERTCMP(object->state, >, FSCACHE_OBJECT_LOOKING_UP); | |
269 | ||
270 | if (fscache_submit_op(object, &op->op) < 0) | |
271 | goto nobufs_unlock; | |
272 | spin_unlock(&cookie->lock); | |
273 | ||
274 | fscache_stat(&fscache_n_retrieval_ops); | |
275 | ||
276 | /* pin the netfs read context in case we need to do the actual netfs | |
277 | * read because we've encountered a cache read failure */ | |
278 | fscache_get_context(object->cookie, op->context); | |
279 | ||
280 | /* we wait for the operation to become active, and then process it | |
281 | * *here*, in this thread, and not in the thread pool */ | |
282 | if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) { | |
283 | _debug(">>> WT"); | |
284 | fscache_stat(&fscache_n_retrieval_op_waits); | |
285 | wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, | |
286 | fscache_wait_bit, TASK_UNINTERRUPTIBLE); | |
287 | _debug("<<< GO"); | |
288 | } | |
289 | ||
290 | /* ask the cache to honour the operation */ | |
291 | if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) { | |
292 | ret = object->cache->ops->allocate_page(op, page, gfp); | |
293 | if (ret == 0) | |
294 | ret = -ENODATA; | |
295 | } else { | |
296 | ret = object->cache->ops->read_or_alloc_page(op, page, gfp); | |
297 | } | |
298 | ||
299 | if (ret == -ENOMEM) | |
300 | fscache_stat(&fscache_n_retrievals_nomem); | |
301 | else if (ret == -ERESTARTSYS) | |
302 | fscache_stat(&fscache_n_retrievals_intr); | |
303 | else if (ret == -ENODATA) | |
304 | fscache_stat(&fscache_n_retrievals_nodata); | |
305 | else if (ret < 0) | |
306 | fscache_stat(&fscache_n_retrievals_nobufs); | |
307 | else | |
308 | fscache_stat(&fscache_n_retrievals_ok); | |
309 | ||
310 | fscache_put_retrieval(op); | |
311 | _leave(" = %d", ret); | |
312 | return ret; | |
313 | ||
314 | nobufs_unlock: | |
315 | spin_unlock(&cookie->lock); | |
316 | kfree(op); | |
317 | nobufs: | |
318 | fscache_stat(&fscache_n_retrievals_nobufs); | |
319 | _leave(" = -ENOBUFS"); | |
320 | return -ENOBUFS; | |
321 | } | |
322 | EXPORT_SYMBOL(__fscache_read_or_alloc_page); | |
323 | ||
324 | /* | |
325 | * read a list of page from the cache or allocate a block in which to store | |
326 | * them | |
327 | * - we return: | |
328 | * -ENOMEM - out of memory, some pages may be being read | |
329 | * -ERESTARTSYS - interrupted, some pages may be being read | |
330 | * -ENOBUFS - no backing object or space available in which to cache any | |
331 | * pages not being read | |
332 | * -ENODATA - no data available in the backing object for some or all of | |
333 | * the pages | |
334 | * 0 - dispatched a read on all pages | |
335 | * | |
336 | * end_io_func() will be called for each page read from the cache as it is | |
337 | * finishes being read | |
338 | * | |
339 | * any pages for which a read is dispatched will be removed from pages and | |
340 | * nr_pages | |
341 | */ | |
342 | int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie, | |
343 | struct address_space *mapping, | |
344 | struct list_head *pages, | |
345 | unsigned *nr_pages, | |
346 | fscache_rw_complete_t end_io_func, | |
347 | void *context, | |
348 | gfp_t gfp) | |
349 | { | |
350 | fscache_pages_retrieval_func_t func; | |
351 | struct fscache_retrieval *op; | |
352 | struct fscache_object *object; | |
353 | int ret; | |
354 | ||
355 | _enter("%p,,%d,,,", cookie, *nr_pages); | |
356 | ||
357 | fscache_stat(&fscache_n_retrievals); | |
358 | ||
359 | if (hlist_empty(&cookie->backing_objects)) | |
360 | goto nobufs; | |
361 | ||
362 | ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); | |
363 | ASSERTCMP(*nr_pages, >, 0); | |
364 | ASSERT(!list_empty(pages)); | |
365 | ||
366 | if (fscache_wait_for_deferred_lookup(cookie) < 0) | |
367 | return -ERESTARTSYS; | |
368 | ||
369 | op = fscache_alloc_retrieval(mapping, end_io_func, context); | |
370 | if (!op) | |
371 | return -ENOMEM; | |
372 | ||
373 | spin_lock(&cookie->lock); | |
374 | ||
375 | if (hlist_empty(&cookie->backing_objects)) | |
376 | goto nobufs_unlock; | |
377 | object = hlist_entry(cookie->backing_objects.first, | |
378 | struct fscache_object, cookie_link); | |
379 | ||
380 | if (fscache_submit_op(object, &op->op) < 0) | |
381 | goto nobufs_unlock; | |
382 | spin_unlock(&cookie->lock); | |
383 | ||
384 | fscache_stat(&fscache_n_retrieval_ops); | |
385 | ||
386 | /* pin the netfs read context in case we need to do the actual netfs | |
387 | * read because we've encountered a cache read failure */ | |
388 | fscache_get_context(object->cookie, op->context); | |
389 | ||
390 | /* we wait for the operation to become active, and then process it | |
391 | * *here*, in this thread, and not in the thread pool */ | |
392 | if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) { | |
393 | _debug(">>> WT"); | |
394 | fscache_stat(&fscache_n_retrieval_op_waits); | |
395 | wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, | |
396 | fscache_wait_bit, TASK_UNINTERRUPTIBLE); | |
397 | _debug("<<< GO"); | |
398 | } | |
399 | ||
400 | /* ask the cache to honour the operation */ | |
401 | if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) | |
402 | func = object->cache->ops->allocate_pages; | |
403 | else | |
404 | func = object->cache->ops->read_or_alloc_pages; | |
405 | ret = func(op, pages, nr_pages, gfp); | |
406 | ||
407 | if (ret == -ENOMEM) | |
408 | fscache_stat(&fscache_n_retrievals_nomem); | |
409 | else if (ret == -ERESTARTSYS) | |
410 | fscache_stat(&fscache_n_retrievals_intr); | |
411 | else if (ret == -ENODATA) | |
412 | fscache_stat(&fscache_n_retrievals_nodata); | |
413 | else if (ret < 0) | |
414 | fscache_stat(&fscache_n_retrievals_nobufs); | |
415 | else | |
416 | fscache_stat(&fscache_n_retrievals_ok); | |
417 | ||
418 | fscache_put_retrieval(op); | |
419 | _leave(" = %d", ret); | |
420 | return ret; | |
421 | ||
422 | nobufs_unlock: | |
423 | spin_unlock(&cookie->lock); | |
424 | kfree(op); | |
425 | nobufs: | |
426 | fscache_stat(&fscache_n_retrievals_nobufs); | |
427 | _leave(" = -ENOBUFS"); | |
428 | return -ENOBUFS; | |
429 | } | |
430 | EXPORT_SYMBOL(__fscache_read_or_alloc_pages); | |
431 | ||
432 | /* | |
433 | * allocate a block in the cache on which to store a page | |
434 | * - we return: | |
435 | * -ENOMEM - out of memory, nothing done | |
436 | * -ERESTARTSYS - interrupted | |
437 | * -ENOBUFS - no backing object available in which to cache the block | |
438 | * 0 - block allocated | |
439 | */ | |
440 | int __fscache_alloc_page(struct fscache_cookie *cookie, | |
441 | struct page *page, | |
442 | gfp_t gfp) | |
443 | { | |
444 | struct fscache_retrieval *op; | |
445 | struct fscache_object *object; | |
446 | int ret; | |
447 | ||
448 | _enter("%p,%p,,,", cookie, page); | |
449 | ||
450 | fscache_stat(&fscache_n_allocs); | |
451 | ||
452 | if (hlist_empty(&cookie->backing_objects)) | |
453 | goto nobufs; | |
454 | ||
455 | ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); | |
456 | ASSERTCMP(page, !=, NULL); | |
457 | ||
458 | if (fscache_wait_for_deferred_lookup(cookie) < 0) | |
459 | return -ERESTARTSYS; | |
460 | ||
461 | op = fscache_alloc_retrieval(page->mapping, NULL, NULL); | |
462 | if (!op) | |
463 | return -ENOMEM; | |
464 | ||
465 | spin_lock(&cookie->lock); | |
466 | ||
467 | if (hlist_empty(&cookie->backing_objects)) | |
468 | goto nobufs_unlock; | |
469 | object = hlist_entry(cookie->backing_objects.first, | |
470 | struct fscache_object, cookie_link); | |
471 | ||
472 | if (fscache_submit_op(object, &op->op) < 0) | |
473 | goto nobufs_unlock; | |
474 | spin_unlock(&cookie->lock); | |
475 | ||
476 | fscache_stat(&fscache_n_alloc_ops); | |
477 | ||
478 | if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) { | |
479 | _debug(">>> WT"); | |
480 | fscache_stat(&fscache_n_alloc_op_waits); | |
481 | wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, | |
482 | fscache_wait_bit, TASK_UNINTERRUPTIBLE); | |
483 | _debug("<<< GO"); | |
484 | } | |
485 | ||
486 | /* ask the cache to honour the operation */ | |
487 | ret = object->cache->ops->allocate_page(op, page, gfp); | |
488 | ||
489 | if (ret < 0) | |
490 | fscache_stat(&fscache_n_allocs_nobufs); | |
491 | else | |
492 | fscache_stat(&fscache_n_allocs_ok); | |
493 | ||
494 | fscache_put_retrieval(op); | |
495 | _leave(" = %d", ret); | |
496 | return ret; | |
497 | ||
498 | nobufs_unlock: | |
499 | spin_unlock(&cookie->lock); | |
500 | kfree(op); | |
501 | nobufs: | |
502 | fscache_stat(&fscache_n_allocs_nobufs); | |
503 | _leave(" = -ENOBUFS"); | |
504 | return -ENOBUFS; | |
505 | } | |
506 | EXPORT_SYMBOL(__fscache_alloc_page); | |
507 | ||
508 | /* | |
509 | * release a write op reference | |
510 | */ | |
511 | static void fscache_release_write_op(struct fscache_operation *_op) | |
512 | { | |
513 | _enter("{OP%x}", _op->debug_id); | |
514 | } | |
515 | ||
516 | /* | |
517 | * perform the background storage of a page into the cache | |
518 | */ | |
519 | static void fscache_write_op(struct fscache_operation *_op) | |
520 | { | |
521 | struct fscache_storage *op = | |
522 | container_of(_op, struct fscache_storage, op); | |
523 | struct fscache_object *object = op->op.object; | |
524 | struct fscache_cookie *cookie = object->cookie; | |
525 | struct page *page; | |
526 | unsigned n; | |
527 | void *results[1]; | |
528 | int ret; | |
529 | ||
530 | _enter("{OP%x,%d}", op->op.debug_id, atomic_read(&op->op.usage)); | |
531 | ||
532 | spin_lock(&cookie->lock); | |
533 | spin_lock(&object->lock); | |
534 | ||
535 | if (!fscache_object_is_active(object)) { | |
536 | spin_unlock(&object->lock); | |
537 | spin_unlock(&cookie->lock); | |
538 | _leave(""); | |
539 | return; | |
540 | } | |
541 | ||
542 | fscache_stat(&fscache_n_store_calls); | |
543 | ||
544 | /* find a page to store */ | |
545 | page = NULL; | |
546 | n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0, 1, | |
547 | FSCACHE_COOKIE_PENDING_TAG); | |
548 | if (n != 1) | |
549 | goto superseded; | |
550 | page = results[0]; | |
551 | _debug("gang %d [%lx]", n, page->index); | |
552 | if (page->index > op->store_limit) | |
553 | goto superseded; | |
554 | ||
555 | radix_tree_tag_clear(&cookie->stores, page->index, | |
556 | FSCACHE_COOKIE_PENDING_TAG); | |
557 | ||
558 | spin_unlock(&object->lock); | |
559 | spin_unlock(&cookie->lock); | |
560 | ||
561 | if (page) { | |
562 | ret = object->cache->ops->write_page(op, page); | |
563 | fscache_end_page_write(cookie, page); | |
564 | page_cache_release(page); | |
565 | if (ret < 0) | |
566 | fscache_abort_object(object); | |
567 | else | |
568 | fscache_enqueue_operation(&op->op); | |
569 | } | |
570 | ||
571 | _leave(""); | |
572 | return; | |
573 | ||
574 | superseded: | |
575 | /* this writer is going away and there aren't any more things to | |
576 | * write */ | |
577 | _debug("cease"); | |
578 | clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); | |
579 | spin_unlock(&object->lock); | |
580 | spin_unlock(&cookie->lock); | |
581 | _leave(""); | |
582 | } | |
583 | ||
584 | /* | |
585 | * request a page be stored in the cache | |
586 | * - returns: | |
587 | * -ENOMEM - out of memory, nothing done | |
588 | * -ENOBUFS - no backing object available in which to cache the page | |
589 | * 0 - dispatched a write - it'll call end_io_func() when finished | |
590 | * | |
591 | * if the cookie still has a backing object at this point, that object can be | |
592 | * in one of a few states with respect to storage processing: | |
593 | * | |
594 | * (1) negative lookup, object not yet created (FSCACHE_COOKIE_CREATING is | |
595 | * set) | |
596 | * | |
597 | * (a) no writes yet (set FSCACHE_COOKIE_PENDING_FILL and queue deferred | |
598 | * fill op) | |
599 | * | |
600 | * (b) writes deferred till post-creation (mark page for writing and | |
601 | * return immediately) | |
602 | * | |
603 | * (2) negative lookup, object created, initial fill being made from netfs | |
604 | * (FSCACHE_COOKIE_INITIAL_FILL is set) | |
605 | * | |
606 | * (a) fill point not yet reached this page (mark page for writing and | |
607 | * return) | |
608 | * | |
609 | * (b) fill point passed this page (queue op to store this page) | |
610 | * | |
611 | * (3) object extant (queue op to store this page) | |
612 | * | |
613 | * any other state is invalid | |
614 | */ | |
615 | int __fscache_write_page(struct fscache_cookie *cookie, | |
616 | struct page *page, | |
617 | gfp_t gfp) | |
618 | { | |
619 | struct fscache_storage *op; | |
620 | struct fscache_object *object; | |
621 | int ret; | |
622 | ||
623 | _enter("%p,%x,", cookie, (u32) page->flags); | |
624 | ||
625 | ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); | |
626 | ASSERT(PageFsCache(page)); | |
627 | ||
628 | fscache_stat(&fscache_n_stores); | |
629 | ||
630 | op = kzalloc(sizeof(*op), GFP_NOIO); | |
631 | if (!op) | |
632 | goto nomem; | |
633 | ||
634 | fscache_operation_init(&op->op, fscache_release_write_op); | |
635 | fscache_operation_init_slow(&op->op, fscache_write_op); | |
636 | op->op.flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_WAITING); | |
637 | ||
638 | ret = radix_tree_preload(gfp & ~__GFP_HIGHMEM); | |
639 | if (ret < 0) | |
640 | goto nomem_free; | |
641 | ||
642 | ret = -ENOBUFS; | |
643 | spin_lock(&cookie->lock); | |
644 | ||
645 | if (hlist_empty(&cookie->backing_objects)) | |
646 | goto nobufs; | |
647 | object = hlist_entry(cookie->backing_objects.first, | |
648 | struct fscache_object, cookie_link); | |
649 | if (test_bit(FSCACHE_IOERROR, &object->cache->flags)) | |
650 | goto nobufs; | |
651 | ||
652 | /* add the page to the pending-storage radix tree on the backing | |
653 | * object */ | |
654 | spin_lock(&object->lock); | |
655 | ||
656 | _debug("store limit %llx", (unsigned long long) object->store_limit); | |
657 | ||
658 | ret = radix_tree_insert(&cookie->stores, page->index, page); | |
659 | if (ret < 0) { | |
660 | if (ret == -EEXIST) | |
661 | goto already_queued; | |
662 | _debug("insert failed %d", ret); | |
663 | goto nobufs_unlock_obj; | |
664 | } | |
665 | ||
666 | radix_tree_tag_set(&cookie->stores, page->index, | |
667 | FSCACHE_COOKIE_PENDING_TAG); | |
668 | page_cache_get(page); | |
669 | ||
670 | /* we only want one writer at a time, but we do need to queue new | |
671 | * writers after exclusive ops */ | |
672 | if (test_and_set_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags)) | |
673 | goto already_pending; | |
674 | ||
675 | spin_unlock(&object->lock); | |
676 | ||
677 | op->op.debug_id = atomic_inc_return(&fscache_op_debug_id); | |
678 | op->store_limit = object->store_limit; | |
679 | ||
680 | if (fscache_submit_op(object, &op->op) < 0) | |
681 | goto submit_failed; | |
682 | ||
683 | spin_unlock(&cookie->lock); | |
684 | radix_tree_preload_end(); | |
685 | fscache_stat(&fscache_n_store_ops); | |
686 | fscache_stat(&fscache_n_stores_ok); | |
687 | ||
688 | /* the slow work queue now carries its own ref on the object */ | |
689 | fscache_put_operation(&op->op); | |
690 | _leave(" = 0"); | |
691 | return 0; | |
692 | ||
693 | already_queued: | |
694 | fscache_stat(&fscache_n_stores_again); | |
695 | already_pending: | |
696 | spin_unlock(&object->lock); | |
697 | spin_unlock(&cookie->lock); | |
698 | radix_tree_preload_end(); | |
699 | kfree(op); | |
700 | fscache_stat(&fscache_n_stores_ok); | |
701 | _leave(" = 0"); | |
702 | return 0; | |
703 | ||
704 | submit_failed: | |
705 | radix_tree_delete(&cookie->stores, page->index); | |
706 | page_cache_release(page); | |
707 | ret = -ENOBUFS; | |
708 | goto nobufs; | |
709 | ||
710 | nobufs_unlock_obj: | |
711 | spin_unlock(&object->lock); | |
712 | nobufs: | |
713 | spin_unlock(&cookie->lock); | |
714 | radix_tree_preload_end(); | |
715 | kfree(op); | |
716 | fscache_stat(&fscache_n_stores_nobufs); | |
717 | _leave(" = -ENOBUFS"); | |
718 | return -ENOBUFS; | |
719 | ||
720 | nomem_free: | |
721 | kfree(op); | |
722 | nomem: | |
723 | fscache_stat(&fscache_n_stores_oom); | |
724 | _leave(" = -ENOMEM"); | |
725 | return -ENOMEM; | |
726 | } | |
727 | EXPORT_SYMBOL(__fscache_write_page); | |
728 | ||
729 | /* | |
730 | * remove a page from the cache | |
731 | */ | |
732 | void __fscache_uncache_page(struct fscache_cookie *cookie, struct page *page) | |
733 | { | |
734 | struct fscache_object *object; | |
735 | ||
736 | _enter(",%p", page); | |
737 | ||
738 | ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); | |
739 | ASSERTCMP(page, !=, NULL); | |
740 | ||
741 | fscache_stat(&fscache_n_uncaches); | |
742 | ||
743 | /* cache withdrawal may beat us to it */ | |
744 | if (!PageFsCache(page)) | |
745 | goto done; | |
746 | ||
747 | /* get the object */ | |
748 | spin_lock(&cookie->lock); | |
749 | ||
750 | if (hlist_empty(&cookie->backing_objects)) { | |
751 | ClearPageFsCache(page); | |
752 | goto done_unlock; | |
753 | } | |
754 | ||
755 | object = hlist_entry(cookie->backing_objects.first, | |
756 | struct fscache_object, cookie_link); | |
757 | ||
758 | /* there might now be stuff on disk we could read */ | |
759 | clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags); | |
760 | ||
761 | /* only invoke the cache backend if we managed to mark the page | |
762 | * uncached here; this deals with synchronisation vs withdrawal */ | |
763 | if (TestClearPageFsCache(page) && | |
764 | object->cache->ops->uncache_page) { | |
765 | /* the cache backend releases the cookie lock */ | |
766 | object->cache->ops->uncache_page(object, page); | |
767 | goto done; | |
768 | } | |
769 | ||
770 | done_unlock: | |
771 | spin_unlock(&cookie->lock); | |
772 | done: | |
773 | _leave(""); | |
774 | } | |
775 | EXPORT_SYMBOL(__fscache_uncache_page); | |
776 | ||
777 | /** | |
778 | * fscache_mark_pages_cached - Mark pages as being cached | |
779 | * @op: The retrieval op pages are being marked for | |
780 | * @pagevec: The pages to be marked | |
781 | * | |
782 | * Mark a bunch of netfs pages as being cached. After this is called, | |
783 | * the netfs must call fscache_uncache_page() to remove the mark. | |
784 | */ | |
785 | void fscache_mark_pages_cached(struct fscache_retrieval *op, | |
786 | struct pagevec *pagevec) | |
787 | { | |
788 | struct fscache_cookie *cookie = op->op.object->cookie; | |
789 | unsigned long loop; | |
790 | ||
791 | #ifdef CONFIG_FSCACHE_STATS | |
792 | atomic_add(pagevec->nr, &fscache_n_marks); | |
793 | #endif | |
794 | ||
795 | for (loop = 0; loop < pagevec->nr; loop++) { | |
796 | struct page *page = pagevec->pages[loop]; | |
797 | ||
798 | _debug("- mark %p{%lx}", page, page->index); | |
799 | if (TestSetPageFsCache(page)) { | |
800 | static bool once_only; | |
801 | if (!once_only) { | |
802 | once_only = true; | |
803 | printk(KERN_WARNING "FS-Cache:" | |
804 | " Cookie type %s marked page %lx" | |
805 | " multiple times\n", | |
806 | cookie->def->name, page->index); | |
807 | } | |
808 | } | |
809 | } | |
810 | ||
811 | if (cookie->def->mark_pages_cached) | |
812 | cookie->def->mark_pages_cached(cookie->netfs_data, | |
813 | op->mapping, pagevec); | |
814 | pagevec_reinit(pagevec); | |
815 | } | |
816 | EXPORT_SYMBOL(fscache_mark_pages_cached); |