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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 <linux/slab.h> | |
18 | #include "internal.h" | |
19 | ||
20 | /* | |
21 | * check to see if a page is being written to the cache | |
22 | */ | |
23 | bool __fscache_check_page_write(struct fscache_cookie *cookie, struct page *page) | |
24 | { | |
25 | void *val; | |
26 | ||
27 | rcu_read_lock(); | |
28 | val = radix_tree_lookup(&cookie->stores, page->index); | |
29 | rcu_read_unlock(); | |
30 | ||
31 | return val != NULL; | |
32 | } | |
33 | EXPORT_SYMBOL(__fscache_check_page_write); | |
34 | ||
35 | /* | |
36 | * wait for a page to finish being written to the cache | |
37 | */ | |
38 | void __fscache_wait_on_page_write(struct fscache_cookie *cookie, struct page *page) | |
39 | { | |
40 | wait_queue_head_t *wq = bit_waitqueue(&cookie->flags, 0); | |
41 | ||
42 | wait_event(*wq, !__fscache_check_page_write(cookie, page)); | |
43 | } | |
44 | EXPORT_SYMBOL(__fscache_wait_on_page_write); | |
45 | ||
46 | /* | |
47 | * decide whether a page can be released, possibly by cancelling a store to it | |
48 | * - we're allowed to sleep if __GFP_WAIT is flagged | |
49 | */ | |
50 | bool __fscache_maybe_release_page(struct fscache_cookie *cookie, | |
51 | struct page *page, | |
52 | gfp_t gfp) | |
53 | { | |
54 | struct page *xpage; | |
55 | void *val; | |
56 | ||
57 | _enter("%p,%p,%x", cookie, page, gfp); | |
58 | ||
59 | try_again: | |
60 | rcu_read_lock(); | |
61 | val = radix_tree_lookup(&cookie->stores, page->index); | |
62 | if (!val) { | |
63 | rcu_read_unlock(); | |
64 | fscache_stat(&fscache_n_store_vmscan_not_storing); | |
65 | __fscache_uncache_page(cookie, page); | |
66 | return true; | |
67 | } | |
68 | ||
69 | /* see if the page is actually undergoing storage - if so we can't get | |
70 | * rid of it till the cache has finished with it */ | |
71 | if (radix_tree_tag_get(&cookie->stores, page->index, | |
72 | FSCACHE_COOKIE_STORING_TAG)) { | |
73 | rcu_read_unlock(); | |
74 | goto page_busy; | |
75 | } | |
76 | ||
77 | /* the page is pending storage, so we attempt to cancel the store and | |
78 | * discard the store request so that the page can be reclaimed */ | |
79 | spin_lock(&cookie->stores_lock); | |
80 | rcu_read_unlock(); | |
81 | ||
82 | if (radix_tree_tag_get(&cookie->stores, page->index, | |
83 | FSCACHE_COOKIE_STORING_TAG)) { | |
84 | /* the page started to undergo storage whilst we were looking, | |
85 | * so now we can only wait or return */ | |
86 | spin_unlock(&cookie->stores_lock); | |
87 | goto page_busy; | |
88 | } | |
89 | ||
90 | xpage = radix_tree_delete(&cookie->stores, page->index); | |
91 | spin_unlock(&cookie->stores_lock); | |
92 | ||
93 | if (xpage) { | |
94 | fscache_stat(&fscache_n_store_vmscan_cancelled); | |
95 | fscache_stat(&fscache_n_store_radix_deletes); | |
96 | ASSERTCMP(xpage, ==, page); | |
97 | } else { | |
98 | fscache_stat(&fscache_n_store_vmscan_gone); | |
99 | } | |
100 | ||
101 | wake_up_bit(&cookie->flags, 0); | |
102 | if (xpage) | |
103 | page_cache_release(xpage); | |
104 | __fscache_uncache_page(cookie, page); | |
105 | return true; | |
106 | ||
107 | page_busy: | |
108 | /* We will wait here if we're allowed to, but that could deadlock the | |
109 | * allocator as the work threads writing to the cache may all end up | |
110 | * sleeping on memory allocation, so we may need to impose a timeout | |
111 | * too. */ | |
112 | if (!(gfp & __GFP_WAIT) || !(gfp & __GFP_FS)) { | |
113 | fscache_stat(&fscache_n_store_vmscan_busy); | |
114 | return false; | |
115 | } | |
116 | ||
117 | fscache_stat(&fscache_n_store_vmscan_wait); | |
118 | __fscache_wait_on_page_write(cookie, page); | |
119 | gfp &= ~__GFP_WAIT; | |
120 | goto try_again; | |
121 | } | |
122 | EXPORT_SYMBOL(__fscache_maybe_release_page); | |
123 | ||
124 | /* | |
125 | * note that a page has finished being written to the cache | |
126 | */ | |
127 | static void fscache_end_page_write(struct fscache_object *object, | |
128 | struct page *page) | |
129 | { | |
130 | struct fscache_cookie *cookie; | |
131 | struct page *xpage = NULL; | |
132 | ||
133 | spin_lock(&object->lock); | |
134 | cookie = object->cookie; | |
135 | if (cookie) { | |
136 | /* delete the page from the tree if it is now no longer | |
137 | * pending */ | |
138 | spin_lock(&cookie->stores_lock); | |
139 | radix_tree_tag_clear(&cookie->stores, page->index, | |
140 | FSCACHE_COOKIE_STORING_TAG); | |
141 | if (!radix_tree_tag_get(&cookie->stores, page->index, | |
142 | FSCACHE_COOKIE_PENDING_TAG)) { | |
143 | fscache_stat(&fscache_n_store_radix_deletes); | |
144 | xpage = radix_tree_delete(&cookie->stores, page->index); | |
145 | } | |
146 | spin_unlock(&cookie->stores_lock); | |
147 | wake_up_bit(&cookie->flags, 0); | |
148 | } | |
149 | spin_unlock(&object->lock); | |
150 | if (xpage) | |
151 | page_cache_release(xpage); | |
152 | } | |
153 | ||
154 | /* | |
155 | * actually apply the changed attributes to a cache object | |
156 | */ | |
157 | static void fscache_attr_changed_op(struct fscache_operation *op) | |
158 | { | |
159 | struct fscache_object *object = op->object; | |
160 | int ret; | |
161 | ||
162 | _enter("{OBJ%x OP%x}", object->debug_id, op->debug_id); | |
163 | ||
164 | fscache_stat(&fscache_n_attr_changed_calls); | |
165 | ||
166 | if (fscache_object_is_active(object) && | |
167 | fscache_use_cookie(object)) { | |
168 | fscache_stat(&fscache_n_cop_attr_changed); | |
169 | ret = object->cache->ops->attr_changed(object); | |
170 | fscache_stat_d(&fscache_n_cop_attr_changed); | |
171 | fscache_unuse_cookie(object); | |
172 | if (ret < 0) | |
173 | fscache_abort_object(object); | |
174 | } | |
175 | ||
176 | fscache_op_complete(op, true); | |
177 | _leave(""); | |
178 | } | |
179 | ||
180 | /* | |
181 | * notification that the attributes on an object have changed | |
182 | */ | |
183 | int __fscache_attr_changed(struct fscache_cookie *cookie) | |
184 | { | |
185 | struct fscache_operation *op; | |
186 | struct fscache_object *object; | |
187 | ||
188 | _enter("%p", cookie); | |
189 | ||
190 | ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); | |
191 | ||
192 | fscache_stat(&fscache_n_attr_changed); | |
193 | ||
194 | op = kzalloc(sizeof(*op), GFP_KERNEL); | |
195 | if (!op) { | |
196 | fscache_stat(&fscache_n_attr_changed_nomem); | |
197 | _leave(" = -ENOMEM"); | |
198 | return -ENOMEM; | |
199 | } | |
200 | ||
201 | fscache_operation_init(op, fscache_attr_changed_op, NULL); | |
202 | op->flags = FSCACHE_OP_ASYNC | (1 << FSCACHE_OP_EXCLUSIVE); | |
203 | ||
204 | spin_lock(&cookie->lock); | |
205 | ||
206 | if (hlist_empty(&cookie->backing_objects)) | |
207 | goto nobufs; | |
208 | object = hlist_entry(cookie->backing_objects.first, | |
209 | struct fscache_object, cookie_link); | |
210 | ||
211 | if (fscache_submit_exclusive_op(object, op) < 0) | |
212 | goto nobufs; | |
213 | spin_unlock(&cookie->lock); | |
214 | fscache_stat(&fscache_n_attr_changed_ok); | |
215 | fscache_put_operation(op); | |
216 | _leave(" = 0"); | |
217 | return 0; | |
218 | ||
219 | nobufs: | |
220 | spin_unlock(&cookie->lock); | |
221 | kfree(op); | |
222 | fscache_stat(&fscache_n_attr_changed_nobufs); | |
223 | _leave(" = %d", -ENOBUFS); | |
224 | return -ENOBUFS; | |
225 | } | |
226 | EXPORT_SYMBOL(__fscache_attr_changed); | |
227 | ||
228 | /* | |
229 | * release a retrieval op reference | |
230 | */ | |
231 | static void fscache_release_retrieval_op(struct fscache_operation *_op) | |
232 | { | |
233 | struct fscache_retrieval *op = | |
234 | container_of(_op, struct fscache_retrieval, op); | |
235 | ||
236 | _enter("{OP%x}", op->op.debug_id); | |
237 | ||
238 | ASSERTCMP(op->n_pages, ==, 0); | |
239 | ||
240 | fscache_hist(fscache_retrieval_histogram, op->start_time); | |
241 | if (op->context) | |
242 | fscache_put_context(op->op.object->cookie, op->context); | |
243 | ||
244 | _leave(""); | |
245 | } | |
246 | ||
247 | /* | |
248 | * allocate a retrieval op | |
249 | */ | |
250 | static struct fscache_retrieval *fscache_alloc_retrieval( | |
251 | struct fscache_cookie *cookie, | |
252 | struct address_space *mapping, | |
253 | fscache_rw_complete_t end_io_func, | |
254 | void *context) | |
255 | { | |
256 | struct fscache_retrieval *op; | |
257 | ||
258 | /* allocate a retrieval operation and attempt to submit it */ | |
259 | op = kzalloc(sizeof(*op), GFP_NOIO); | |
260 | if (!op) { | |
261 | fscache_stat(&fscache_n_retrievals_nomem); | |
262 | return NULL; | |
263 | } | |
264 | ||
265 | fscache_operation_init(&op->op, NULL, fscache_release_retrieval_op); | |
266 | atomic_inc(&cookie->n_active); | |
267 | op->op.flags = FSCACHE_OP_MYTHREAD | | |
268 | (1UL << FSCACHE_OP_WAITING) | | |
269 | (1UL << FSCACHE_OP_UNUSE_COOKIE); | |
270 | op->mapping = mapping; | |
271 | op->end_io_func = end_io_func; | |
272 | op->context = context; | |
273 | op->start_time = jiffies; | |
274 | INIT_LIST_HEAD(&op->to_do); | |
275 | return op; | |
276 | } | |
277 | ||
278 | /* | |
279 | * wait for a deferred lookup to complete | |
280 | */ | |
281 | static int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie) | |
282 | { | |
283 | unsigned long jif; | |
284 | ||
285 | _enter(""); | |
286 | ||
287 | if (!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)) { | |
288 | _leave(" = 0 [imm]"); | |
289 | return 0; | |
290 | } | |
291 | ||
292 | fscache_stat(&fscache_n_retrievals_wait); | |
293 | ||
294 | jif = jiffies; | |
295 | if (wait_on_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP, | |
296 | fscache_wait_bit_interruptible, | |
297 | TASK_INTERRUPTIBLE) != 0) { | |
298 | fscache_stat(&fscache_n_retrievals_intr); | |
299 | _leave(" = -ERESTARTSYS"); | |
300 | return -ERESTARTSYS; | |
301 | } | |
302 | ||
303 | ASSERT(!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)); | |
304 | ||
305 | smp_rmb(); | |
306 | fscache_hist(fscache_retrieval_delay_histogram, jif); | |
307 | _leave(" = 0 [dly]"); | |
308 | return 0; | |
309 | } | |
310 | ||
311 | /* | |
312 | * Handle cancellation of a pending retrieval op | |
313 | */ | |
314 | static void fscache_do_cancel_retrieval(struct fscache_operation *_op) | |
315 | { | |
316 | struct fscache_retrieval *op = | |
317 | container_of(_op, struct fscache_retrieval, op); | |
318 | ||
319 | op->n_pages = 0; | |
320 | } | |
321 | ||
322 | /* | |
323 | * wait for an object to become active (or dead) | |
324 | */ | |
325 | static int fscache_wait_for_retrieval_activation(struct fscache_object *object, | |
326 | struct fscache_retrieval *op, | |
327 | atomic_t *stat_op_waits, | |
328 | atomic_t *stat_object_dead) | |
329 | { | |
330 | int ret; | |
331 | ||
332 | if (!test_bit(FSCACHE_OP_WAITING, &op->op.flags)) | |
333 | goto check_if_dead; | |
334 | ||
335 | _debug(">>> WT"); | |
336 | fscache_stat(stat_op_waits); | |
337 | if (wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, | |
338 | fscache_wait_bit_interruptible, | |
339 | TASK_INTERRUPTIBLE) != 0) { | |
340 | ret = fscache_cancel_op(&op->op, fscache_do_cancel_retrieval); | |
341 | if (ret == 0) | |
342 | return -ERESTARTSYS; | |
343 | ||
344 | /* it's been removed from the pending queue by another party, | |
345 | * so we should get to run shortly */ | |
346 | wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, | |
347 | fscache_wait_bit, TASK_UNINTERRUPTIBLE); | |
348 | } | |
349 | _debug("<<< GO"); | |
350 | ||
351 | check_if_dead: | |
352 | if (op->op.state == FSCACHE_OP_ST_CANCELLED) { | |
353 | fscache_stat(stat_object_dead); | |
354 | _leave(" = -ENOBUFS [cancelled]"); | |
355 | return -ENOBUFS; | |
356 | } | |
357 | if (unlikely(fscache_object_is_dead(object))) { | |
358 | pr_err("%s() = -ENOBUFS [obj dead %d]\n", __func__, op->op.state); | |
359 | fscache_cancel_op(&op->op, fscache_do_cancel_retrieval); | |
360 | fscache_stat(stat_object_dead); | |
361 | return -ENOBUFS; | |
362 | } | |
363 | return 0; | |
364 | } | |
365 | ||
366 | /* | |
367 | * read a page from the cache or allocate a block in which to store it | |
368 | * - we return: | |
369 | * -ENOMEM - out of memory, nothing done | |
370 | * -ERESTARTSYS - interrupted | |
371 | * -ENOBUFS - no backing object available in which to cache the block | |
372 | * -ENODATA - no data available in the backing object for this block | |
373 | * 0 - dispatched a read - it'll call end_io_func() when finished | |
374 | */ | |
375 | int __fscache_read_or_alloc_page(struct fscache_cookie *cookie, | |
376 | struct page *page, | |
377 | fscache_rw_complete_t end_io_func, | |
378 | void *context, | |
379 | gfp_t gfp) | |
380 | { | |
381 | struct fscache_retrieval *op; | |
382 | struct fscache_object *object; | |
383 | int ret; | |
384 | ||
385 | _enter("%p,%p,,,", cookie, page); | |
386 | ||
387 | fscache_stat(&fscache_n_retrievals); | |
388 | ||
389 | if (hlist_empty(&cookie->backing_objects)) | |
390 | goto nobufs; | |
391 | ||
392 | if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) { | |
393 | _leave(" = -ENOBUFS [invalidating]"); | |
394 | return -ENOBUFS; | |
395 | } | |
396 | ||
397 | ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); | |
398 | ASSERTCMP(page, !=, NULL); | |
399 | ||
400 | if (fscache_wait_for_deferred_lookup(cookie) < 0) | |
401 | return -ERESTARTSYS; | |
402 | ||
403 | op = fscache_alloc_retrieval(cookie, page->mapping, | |
404 | end_io_func,context); | |
405 | if (!op) { | |
406 | _leave(" = -ENOMEM"); | |
407 | return -ENOMEM; | |
408 | } | |
409 | op->n_pages = 1; | |
410 | ||
411 | spin_lock(&cookie->lock); | |
412 | ||
413 | if (hlist_empty(&cookie->backing_objects)) | |
414 | goto nobufs_unlock; | |
415 | object = hlist_entry(cookie->backing_objects.first, | |
416 | struct fscache_object, cookie_link); | |
417 | ||
418 | ASSERT(test_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags)); | |
419 | ||
420 | atomic_inc(&object->n_reads); | |
421 | __set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags); | |
422 | ||
423 | if (fscache_submit_op(object, &op->op) < 0) | |
424 | goto nobufs_unlock_dec; | |
425 | spin_unlock(&cookie->lock); | |
426 | ||
427 | fscache_stat(&fscache_n_retrieval_ops); | |
428 | ||
429 | /* pin the netfs read context in case we need to do the actual netfs | |
430 | * read because we've encountered a cache read failure */ | |
431 | fscache_get_context(object->cookie, op->context); | |
432 | ||
433 | /* we wait for the operation to become active, and then process it | |
434 | * *here*, in this thread, and not in the thread pool */ | |
435 | ret = fscache_wait_for_retrieval_activation( | |
436 | object, op, | |
437 | __fscache_stat(&fscache_n_retrieval_op_waits), | |
438 | __fscache_stat(&fscache_n_retrievals_object_dead)); | |
439 | if (ret < 0) | |
440 | goto error; | |
441 | ||
442 | /* ask the cache to honour the operation */ | |
443 | if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) { | |
444 | fscache_stat(&fscache_n_cop_allocate_page); | |
445 | ret = object->cache->ops->allocate_page(op, page, gfp); | |
446 | fscache_stat_d(&fscache_n_cop_allocate_page); | |
447 | if (ret == 0) | |
448 | ret = -ENODATA; | |
449 | } else { | |
450 | fscache_stat(&fscache_n_cop_read_or_alloc_page); | |
451 | ret = object->cache->ops->read_or_alloc_page(op, page, gfp); | |
452 | fscache_stat_d(&fscache_n_cop_read_or_alloc_page); | |
453 | } | |
454 | ||
455 | error: | |
456 | if (ret == -ENOMEM) | |
457 | fscache_stat(&fscache_n_retrievals_nomem); | |
458 | else if (ret == -ERESTARTSYS) | |
459 | fscache_stat(&fscache_n_retrievals_intr); | |
460 | else if (ret == -ENODATA) | |
461 | fscache_stat(&fscache_n_retrievals_nodata); | |
462 | else if (ret < 0) | |
463 | fscache_stat(&fscache_n_retrievals_nobufs); | |
464 | else | |
465 | fscache_stat(&fscache_n_retrievals_ok); | |
466 | ||
467 | fscache_put_retrieval(op); | |
468 | _leave(" = %d", ret); | |
469 | return ret; | |
470 | ||
471 | nobufs_unlock_dec: | |
472 | atomic_dec(&object->n_reads); | |
473 | nobufs_unlock: | |
474 | spin_unlock(&cookie->lock); | |
475 | atomic_dec(&cookie->n_active); | |
476 | kfree(op); | |
477 | nobufs: | |
478 | fscache_stat(&fscache_n_retrievals_nobufs); | |
479 | _leave(" = -ENOBUFS"); | |
480 | return -ENOBUFS; | |
481 | } | |
482 | EXPORT_SYMBOL(__fscache_read_or_alloc_page); | |
483 | ||
484 | /* | |
485 | * read a list of page from the cache or allocate a block in which to store | |
486 | * them | |
487 | * - we return: | |
488 | * -ENOMEM - out of memory, some pages may be being read | |
489 | * -ERESTARTSYS - interrupted, some pages may be being read | |
490 | * -ENOBUFS - no backing object or space available in which to cache any | |
491 | * pages not being read | |
492 | * -ENODATA - no data available in the backing object for some or all of | |
493 | * the pages | |
494 | * 0 - dispatched a read on all pages | |
495 | * | |
496 | * end_io_func() will be called for each page read from the cache as it is | |
497 | * finishes being read | |
498 | * | |
499 | * any pages for which a read is dispatched will be removed from pages and | |
500 | * nr_pages | |
501 | */ | |
502 | int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie, | |
503 | struct address_space *mapping, | |
504 | struct list_head *pages, | |
505 | unsigned *nr_pages, | |
506 | fscache_rw_complete_t end_io_func, | |
507 | void *context, | |
508 | gfp_t gfp) | |
509 | { | |
510 | struct fscache_retrieval *op; | |
511 | struct fscache_object *object; | |
512 | int ret; | |
513 | ||
514 | _enter("%p,,%d,,,", cookie, *nr_pages); | |
515 | ||
516 | fscache_stat(&fscache_n_retrievals); | |
517 | ||
518 | if (hlist_empty(&cookie->backing_objects)) | |
519 | goto nobufs; | |
520 | ||
521 | if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) { | |
522 | _leave(" = -ENOBUFS [invalidating]"); | |
523 | return -ENOBUFS; | |
524 | } | |
525 | ||
526 | ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); | |
527 | ASSERTCMP(*nr_pages, >, 0); | |
528 | ASSERT(!list_empty(pages)); | |
529 | ||
530 | if (fscache_wait_for_deferred_lookup(cookie) < 0) | |
531 | return -ERESTARTSYS; | |
532 | ||
533 | op = fscache_alloc_retrieval(cookie, mapping, end_io_func, context); | |
534 | if (!op) | |
535 | return -ENOMEM; | |
536 | op->n_pages = *nr_pages; | |
537 | ||
538 | spin_lock(&cookie->lock); | |
539 | ||
540 | if (hlist_empty(&cookie->backing_objects)) | |
541 | goto nobufs_unlock; | |
542 | object = hlist_entry(cookie->backing_objects.first, | |
543 | struct fscache_object, cookie_link); | |
544 | ||
545 | atomic_inc(&object->n_reads); | |
546 | __set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags); | |
547 | ||
548 | if (fscache_submit_op(object, &op->op) < 0) | |
549 | goto nobufs_unlock_dec; | |
550 | spin_unlock(&cookie->lock); | |
551 | ||
552 | fscache_stat(&fscache_n_retrieval_ops); | |
553 | ||
554 | /* pin the netfs read context in case we need to do the actual netfs | |
555 | * read because we've encountered a cache read failure */ | |
556 | fscache_get_context(object->cookie, op->context); | |
557 | ||
558 | /* we wait for the operation to become active, and then process it | |
559 | * *here*, in this thread, and not in the thread pool */ | |
560 | ret = fscache_wait_for_retrieval_activation( | |
561 | object, op, | |
562 | __fscache_stat(&fscache_n_retrieval_op_waits), | |
563 | __fscache_stat(&fscache_n_retrievals_object_dead)); | |
564 | if (ret < 0) | |
565 | goto error; | |
566 | ||
567 | /* ask the cache to honour the operation */ | |
568 | if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) { | |
569 | fscache_stat(&fscache_n_cop_allocate_pages); | |
570 | ret = object->cache->ops->allocate_pages( | |
571 | op, pages, nr_pages, gfp); | |
572 | fscache_stat_d(&fscache_n_cop_allocate_pages); | |
573 | } else { | |
574 | fscache_stat(&fscache_n_cop_read_or_alloc_pages); | |
575 | ret = object->cache->ops->read_or_alloc_pages( | |
576 | op, pages, nr_pages, gfp); | |
577 | fscache_stat_d(&fscache_n_cop_read_or_alloc_pages); | |
578 | } | |
579 | ||
580 | error: | |
581 | if (ret == -ENOMEM) | |
582 | fscache_stat(&fscache_n_retrievals_nomem); | |
583 | else if (ret == -ERESTARTSYS) | |
584 | fscache_stat(&fscache_n_retrievals_intr); | |
585 | else if (ret == -ENODATA) | |
586 | fscache_stat(&fscache_n_retrievals_nodata); | |
587 | else if (ret < 0) | |
588 | fscache_stat(&fscache_n_retrievals_nobufs); | |
589 | else | |
590 | fscache_stat(&fscache_n_retrievals_ok); | |
591 | ||
592 | fscache_put_retrieval(op); | |
593 | _leave(" = %d", ret); | |
594 | return ret; | |
595 | ||
596 | nobufs_unlock_dec: | |
597 | atomic_dec(&object->n_reads); | |
598 | nobufs_unlock: | |
599 | spin_unlock(&cookie->lock); | |
600 | atomic_dec(&cookie->n_active); | |
601 | kfree(op); | |
602 | nobufs: | |
603 | fscache_stat(&fscache_n_retrievals_nobufs); | |
604 | _leave(" = -ENOBUFS"); | |
605 | return -ENOBUFS; | |
606 | } | |
607 | EXPORT_SYMBOL(__fscache_read_or_alloc_pages); | |
608 | ||
609 | /* | |
610 | * allocate a block in the cache on which to store a page | |
611 | * - we return: | |
612 | * -ENOMEM - out of memory, nothing done | |
613 | * -ERESTARTSYS - interrupted | |
614 | * -ENOBUFS - no backing object available in which to cache the block | |
615 | * 0 - block allocated | |
616 | */ | |
617 | int __fscache_alloc_page(struct fscache_cookie *cookie, | |
618 | struct page *page, | |
619 | gfp_t gfp) | |
620 | { | |
621 | struct fscache_retrieval *op; | |
622 | struct fscache_object *object; | |
623 | int ret; | |
624 | ||
625 | _enter("%p,%p,,,", cookie, page); | |
626 | ||
627 | fscache_stat(&fscache_n_allocs); | |
628 | ||
629 | if (hlist_empty(&cookie->backing_objects)) | |
630 | goto nobufs; | |
631 | ||
632 | ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); | |
633 | ASSERTCMP(page, !=, NULL); | |
634 | ||
635 | if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) { | |
636 | _leave(" = -ENOBUFS [invalidating]"); | |
637 | return -ENOBUFS; | |
638 | } | |
639 | ||
640 | if (fscache_wait_for_deferred_lookup(cookie) < 0) | |
641 | return -ERESTARTSYS; | |
642 | ||
643 | op = fscache_alloc_retrieval(cookie, page->mapping, NULL, NULL); | |
644 | if (!op) | |
645 | return -ENOMEM; | |
646 | op->n_pages = 1; | |
647 | ||
648 | spin_lock(&cookie->lock); | |
649 | ||
650 | if (hlist_empty(&cookie->backing_objects)) | |
651 | goto nobufs_unlock; | |
652 | object = hlist_entry(cookie->backing_objects.first, | |
653 | struct fscache_object, cookie_link); | |
654 | ||
655 | if (fscache_submit_op(object, &op->op) < 0) | |
656 | goto nobufs_unlock; | |
657 | spin_unlock(&cookie->lock); | |
658 | ||
659 | fscache_stat(&fscache_n_alloc_ops); | |
660 | ||
661 | ret = fscache_wait_for_retrieval_activation( | |
662 | object, op, | |
663 | __fscache_stat(&fscache_n_alloc_op_waits), | |
664 | __fscache_stat(&fscache_n_allocs_object_dead)); | |
665 | if (ret < 0) | |
666 | goto error; | |
667 | ||
668 | /* ask the cache to honour the operation */ | |
669 | fscache_stat(&fscache_n_cop_allocate_page); | |
670 | ret = object->cache->ops->allocate_page(op, page, gfp); | |
671 | fscache_stat_d(&fscache_n_cop_allocate_page); | |
672 | ||
673 | error: | |
674 | if (ret == -ERESTARTSYS) | |
675 | fscache_stat(&fscache_n_allocs_intr); | |
676 | else if (ret < 0) | |
677 | fscache_stat(&fscache_n_allocs_nobufs); | |
678 | else | |
679 | fscache_stat(&fscache_n_allocs_ok); | |
680 | ||
681 | fscache_put_retrieval(op); | |
682 | _leave(" = %d", ret); | |
683 | return ret; | |
684 | ||
685 | nobufs_unlock: | |
686 | spin_unlock(&cookie->lock); | |
687 | atomic_dec(&cookie->n_active); | |
688 | kfree(op); | |
689 | nobufs: | |
690 | fscache_stat(&fscache_n_allocs_nobufs); | |
691 | _leave(" = -ENOBUFS"); | |
692 | return -ENOBUFS; | |
693 | } | |
694 | EXPORT_SYMBOL(__fscache_alloc_page); | |
695 | ||
696 | /* | |
697 | * release a write op reference | |
698 | */ | |
699 | static void fscache_release_write_op(struct fscache_operation *_op) | |
700 | { | |
701 | _enter("{OP%x}", _op->debug_id); | |
702 | } | |
703 | ||
704 | /* | |
705 | * perform the background storage of a page into the cache | |
706 | */ | |
707 | static void fscache_write_op(struct fscache_operation *_op) | |
708 | { | |
709 | struct fscache_storage *op = | |
710 | container_of(_op, struct fscache_storage, op); | |
711 | struct fscache_object *object = op->op.object; | |
712 | struct fscache_cookie *cookie; | |
713 | struct page *page; | |
714 | unsigned n; | |
715 | void *results[1]; | |
716 | int ret; | |
717 | ||
718 | _enter("{OP%x,%d}", op->op.debug_id, atomic_read(&op->op.usage)); | |
719 | ||
720 | spin_lock(&object->lock); | |
721 | cookie = object->cookie; | |
722 | ||
723 | if (!fscache_object_is_active(object)) { | |
724 | /* If we get here, then the on-disk cache object likely longer | |
725 | * exists, so we should just cancel this write operation. | |
726 | */ | |
727 | spin_unlock(&object->lock); | |
728 | fscache_op_complete(&op->op, false); | |
729 | _leave(" [inactive]"); | |
730 | return; | |
731 | } | |
732 | ||
733 | if (!cookie) { | |
734 | /* If we get here, then the cookie belonging to the object was | |
735 | * detached, probably by the cookie being withdrawn due to | |
736 | * memory pressure, which means that the pages we might write | |
737 | * to the cache from no longer exist - therefore, we can just | |
738 | * cancel this write operation. | |
739 | */ | |
740 | spin_unlock(&object->lock); | |
741 | fscache_op_complete(&op->op, false); | |
742 | _leave(" [cancel] op{f=%lx s=%u} obj{s=%s f=%lx}", | |
743 | _op->flags, _op->state, object->state->short_name, | |
744 | object->flags); | |
745 | return; | |
746 | } | |
747 | ||
748 | spin_lock(&cookie->stores_lock); | |
749 | ||
750 | fscache_stat(&fscache_n_store_calls); | |
751 | ||
752 | /* find a page to store */ | |
753 | page = NULL; | |
754 | n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0, 1, | |
755 | FSCACHE_COOKIE_PENDING_TAG); | |
756 | if (n != 1) | |
757 | goto superseded; | |
758 | page = results[0]; | |
759 | _debug("gang %d [%lx]", n, page->index); | |
760 | if (page->index > op->store_limit) { | |
761 | fscache_stat(&fscache_n_store_pages_over_limit); | |
762 | goto superseded; | |
763 | } | |
764 | ||
765 | radix_tree_tag_set(&cookie->stores, page->index, | |
766 | FSCACHE_COOKIE_STORING_TAG); | |
767 | radix_tree_tag_clear(&cookie->stores, page->index, | |
768 | FSCACHE_COOKIE_PENDING_TAG); | |
769 | ||
770 | spin_unlock(&cookie->stores_lock); | |
771 | spin_unlock(&object->lock); | |
772 | ||
773 | fscache_stat(&fscache_n_store_pages); | |
774 | fscache_stat(&fscache_n_cop_write_page); | |
775 | ret = object->cache->ops->write_page(op, page); | |
776 | fscache_stat_d(&fscache_n_cop_write_page); | |
777 | fscache_end_page_write(object, page); | |
778 | if (ret < 0) { | |
779 | fscache_abort_object(object); | |
780 | fscache_op_complete(&op->op, true); | |
781 | } else { | |
782 | fscache_enqueue_operation(&op->op); | |
783 | } | |
784 | ||
785 | _leave(""); | |
786 | return; | |
787 | ||
788 | superseded: | |
789 | /* this writer is going away and there aren't any more things to | |
790 | * write */ | |
791 | _debug("cease"); | |
792 | spin_unlock(&cookie->stores_lock); | |
793 | clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); | |
794 | spin_unlock(&object->lock); | |
795 | fscache_op_complete(&op->op, true); | |
796 | _leave(""); | |
797 | } | |
798 | ||
799 | /* | |
800 | * Clear the pages pending writing for invalidation | |
801 | */ | |
802 | void fscache_invalidate_writes(struct fscache_cookie *cookie) | |
803 | { | |
804 | struct page *page; | |
805 | void *results[16]; | |
806 | int n, i; | |
807 | ||
808 | _enter(""); | |
809 | ||
810 | for (;;) { | |
811 | spin_lock(&cookie->stores_lock); | |
812 | n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0, | |
813 | ARRAY_SIZE(results), | |
814 | FSCACHE_COOKIE_PENDING_TAG); | |
815 | if (n == 0) { | |
816 | spin_unlock(&cookie->stores_lock); | |
817 | break; | |
818 | } | |
819 | ||
820 | for (i = n - 1; i >= 0; i--) { | |
821 | page = results[i]; | |
822 | radix_tree_delete(&cookie->stores, page->index); | |
823 | } | |
824 | ||
825 | spin_unlock(&cookie->stores_lock); | |
826 | ||
827 | for (i = n - 1; i >= 0; i--) | |
828 | page_cache_release(results[i]); | |
829 | } | |
830 | ||
831 | _leave(""); | |
832 | } | |
833 | ||
834 | /* | |
835 | * request a page be stored in the cache | |
836 | * - returns: | |
837 | * -ENOMEM - out of memory, nothing done | |
838 | * -ENOBUFS - no backing object available in which to cache the page | |
839 | * 0 - dispatched a write - it'll call end_io_func() when finished | |
840 | * | |
841 | * if the cookie still has a backing object at this point, that object can be | |
842 | * in one of a few states with respect to storage processing: | |
843 | * | |
844 | * (1) negative lookup, object not yet created (FSCACHE_COOKIE_CREATING is | |
845 | * set) | |
846 | * | |
847 | * (a) no writes yet | |
848 | * | |
849 | * (b) writes deferred till post-creation (mark page for writing and | |
850 | * return immediately) | |
851 | * | |
852 | * (2) negative lookup, object created, initial fill being made from netfs | |
853 | * | |
854 | * (a) fill point not yet reached this page (mark page for writing and | |
855 | * return) | |
856 | * | |
857 | * (b) fill point passed this page (queue op to store this page) | |
858 | * | |
859 | * (3) object extant (queue op to store this page) | |
860 | * | |
861 | * any other state is invalid | |
862 | */ | |
863 | int __fscache_write_page(struct fscache_cookie *cookie, | |
864 | struct page *page, | |
865 | gfp_t gfp) | |
866 | { | |
867 | struct fscache_storage *op; | |
868 | struct fscache_object *object; | |
869 | int ret; | |
870 | ||
871 | _enter("%p,%x,", cookie, (u32) page->flags); | |
872 | ||
873 | ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); | |
874 | ASSERT(PageFsCache(page)); | |
875 | ||
876 | fscache_stat(&fscache_n_stores); | |
877 | ||
878 | if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) { | |
879 | _leave(" = -ENOBUFS [invalidating]"); | |
880 | return -ENOBUFS; | |
881 | } | |
882 | ||
883 | op = kzalloc(sizeof(*op), GFP_NOIO | __GFP_NOMEMALLOC | __GFP_NORETRY); | |
884 | if (!op) | |
885 | goto nomem; | |
886 | ||
887 | fscache_operation_init(&op->op, fscache_write_op, | |
888 | fscache_release_write_op); | |
889 | op->op.flags = FSCACHE_OP_ASYNC | | |
890 | (1 << FSCACHE_OP_WAITING) | | |
891 | (1 << FSCACHE_OP_UNUSE_COOKIE); | |
892 | ||
893 | ret = radix_tree_preload(gfp & ~__GFP_HIGHMEM); | |
894 | if (ret < 0) | |
895 | goto nomem_free; | |
896 | ||
897 | ret = -ENOBUFS; | |
898 | spin_lock(&cookie->lock); | |
899 | ||
900 | if (hlist_empty(&cookie->backing_objects)) | |
901 | goto nobufs; | |
902 | object = hlist_entry(cookie->backing_objects.first, | |
903 | struct fscache_object, cookie_link); | |
904 | if (test_bit(FSCACHE_IOERROR, &object->cache->flags)) | |
905 | goto nobufs; | |
906 | ||
907 | /* add the page to the pending-storage radix tree on the backing | |
908 | * object */ | |
909 | spin_lock(&object->lock); | |
910 | spin_lock(&cookie->stores_lock); | |
911 | ||
912 | _debug("store limit %llx", (unsigned long long) object->store_limit); | |
913 | ||
914 | ret = radix_tree_insert(&cookie->stores, page->index, page); | |
915 | if (ret < 0) { | |
916 | if (ret == -EEXIST) | |
917 | goto already_queued; | |
918 | _debug("insert failed %d", ret); | |
919 | goto nobufs_unlock_obj; | |
920 | } | |
921 | ||
922 | radix_tree_tag_set(&cookie->stores, page->index, | |
923 | FSCACHE_COOKIE_PENDING_TAG); | |
924 | page_cache_get(page); | |
925 | ||
926 | /* we only want one writer at a time, but we do need to queue new | |
927 | * writers after exclusive ops */ | |
928 | if (test_and_set_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags)) | |
929 | goto already_pending; | |
930 | ||
931 | spin_unlock(&cookie->stores_lock); | |
932 | spin_unlock(&object->lock); | |
933 | ||
934 | op->op.debug_id = atomic_inc_return(&fscache_op_debug_id); | |
935 | op->store_limit = object->store_limit; | |
936 | ||
937 | atomic_inc(&cookie->n_active); | |
938 | if (fscache_submit_op(object, &op->op) < 0) | |
939 | goto submit_failed; | |
940 | ||
941 | spin_unlock(&cookie->lock); | |
942 | radix_tree_preload_end(); | |
943 | fscache_stat(&fscache_n_store_ops); | |
944 | fscache_stat(&fscache_n_stores_ok); | |
945 | ||
946 | /* the work queue now carries its own ref on the object */ | |
947 | fscache_put_operation(&op->op); | |
948 | _leave(" = 0"); | |
949 | return 0; | |
950 | ||
951 | already_queued: | |
952 | fscache_stat(&fscache_n_stores_again); | |
953 | already_pending: | |
954 | spin_unlock(&cookie->stores_lock); | |
955 | spin_unlock(&object->lock); | |
956 | spin_unlock(&cookie->lock); | |
957 | radix_tree_preload_end(); | |
958 | kfree(op); | |
959 | fscache_stat(&fscache_n_stores_ok); | |
960 | _leave(" = 0"); | |
961 | return 0; | |
962 | ||
963 | submit_failed: | |
964 | atomic_dec(&cookie->n_active); | |
965 | spin_lock(&cookie->stores_lock); | |
966 | radix_tree_delete(&cookie->stores, page->index); | |
967 | spin_unlock(&cookie->stores_lock); | |
968 | page_cache_release(page); | |
969 | ret = -ENOBUFS; | |
970 | goto nobufs; | |
971 | ||
972 | nobufs_unlock_obj: | |
973 | spin_unlock(&cookie->stores_lock); | |
974 | spin_unlock(&object->lock); | |
975 | nobufs: | |
976 | spin_unlock(&cookie->lock); | |
977 | radix_tree_preload_end(); | |
978 | kfree(op); | |
979 | fscache_stat(&fscache_n_stores_nobufs); | |
980 | _leave(" = -ENOBUFS"); | |
981 | return -ENOBUFS; | |
982 | ||
983 | nomem_free: | |
984 | kfree(op); | |
985 | nomem: | |
986 | fscache_stat(&fscache_n_stores_oom); | |
987 | _leave(" = -ENOMEM"); | |
988 | return -ENOMEM; | |
989 | } | |
990 | EXPORT_SYMBOL(__fscache_write_page); | |
991 | ||
992 | /* | |
993 | * remove a page from the cache | |
994 | */ | |
995 | void __fscache_uncache_page(struct fscache_cookie *cookie, struct page *page) | |
996 | { | |
997 | struct fscache_object *object; | |
998 | ||
999 | _enter(",%p", page); | |
1000 | ||
1001 | ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); | |
1002 | ASSERTCMP(page, !=, NULL); | |
1003 | ||
1004 | fscache_stat(&fscache_n_uncaches); | |
1005 | ||
1006 | /* cache withdrawal may beat us to it */ | |
1007 | if (!PageFsCache(page)) | |
1008 | goto done; | |
1009 | ||
1010 | /* get the object */ | |
1011 | spin_lock(&cookie->lock); | |
1012 | ||
1013 | if (hlist_empty(&cookie->backing_objects)) { | |
1014 | ClearPageFsCache(page); | |
1015 | goto done_unlock; | |
1016 | } | |
1017 | ||
1018 | object = hlist_entry(cookie->backing_objects.first, | |
1019 | struct fscache_object, cookie_link); | |
1020 | ||
1021 | /* there might now be stuff on disk we could read */ | |
1022 | clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags); | |
1023 | ||
1024 | /* only invoke the cache backend if we managed to mark the page | |
1025 | * uncached here; this deals with synchronisation vs withdrawal */ | |
1026 | if (TestClearPageFsCache(page) && | |
1027 | object->cache->ops->uncache_page) { | |
1028 | /* the cache backend releases the cookie lock */ | |
1029 | fscache_stat(&fscache_n_cop_uncache_page); | |
1030 | object->cache->ops->uncache_page(object, page); | |
1031 | fscache_stat_d(&fscache_n_cop_uncache_page); | |
1032 | goto done; | |
1033 | } | |
1034 | ||
1035 | done_unlock: | |
1036 | spin_unlock(&cookie->lock); | |
1037 | done: | |
1038 | _leave(""); | |
1039 | } | |
1040 | EXPORT_SYMBOL(__fscache_uncache_page); | |
1041 | ||
1042 | /** | |
1043 | * fscache_mark_page_cached - Mark a page as being cached | |
1044 | * @op: The retrieval op pages are being marked for | |
1045 | * @page: The page to be marked | |
1046 | * | |
1047 | * Mark a netfs page as being cached. After this is called, the netfs | |
1048 | * must call fscache_uncache_page() to remove the mark. | |
1049 | */ | |
1050 | void fscache_mark_page_cached(struct fscache_retrieval *op, struct page *page) | |
1051 | { | |
1052 | struct fscache_cookie *cookie = op->op.object->cookie; | |
1053 | ||
1054 | #ifdef CONFIG_FSCACHE_STATS | |
1055 | atomic_inc(&fscache_n_marks); | |
1056 | #endif | |
1057 | ||
1058 | _debug("- mark %p{%lx}", page, page->index); | |
1059 | if (TestSetPageFsCache(page)) { | |
1060 | static bool once_only; | |
1061 | if (!once_only) { | |
1062 | once_only = true; | |
1063 | printk(KERN_WARNING "FS-Cache:" | |
1064 | " Cookie type %s marked page %lx" | |
1065 | " multiple times\n", | |
1066 | cookie->def->name, page->index); | |
1067 | } | |
1068 | } | |
1069 | ||
1070 | if (cookie->def->mark_page_cached) | |
1071 | cookie->def->mark_page_cached(cookie->netfs_data, | |
1072 | op->mapping, page); | |
1073 | } | |
1074 | EXPORT_SYMBOL(fscache_mark_page_cached); | |
1075 | ||
1076 | /** | |
1077 | * fscache_mark_pages_cached - Mark pages as being cached | |
1078 | * @op: The retrieval op pages are being marked for | |
1079 | * @pagevec: The pages to be marked | |
1080 | * | |
1081 | * Mark a bunch of netfs pages as being cached. After this is called, | |
1082 | * the netfs must call fscache_uncache_page() to remove the mark. | |
1083 | */ | |
1084 | void fscache_mark_pages_cached(struct fscache_retrieval *op, | |
1085 | struct pagevec *pagevec) | |
1086 | { | |
1087 | unsigned long loop; | |
1088 | ||
1089 | for (loop = 0; loop < pagevec->nr; loop++) | |
1090 | fscache_mark_page_cached(op, pagevec->pages[loop]); | |
1091 | ||
1092 | pagevec_reinit(pagevec); | |
1093 | } | |
1094 | EXPORT_SYMBOL(fscache_mark_pages_cached); | |
1095 | ||
1096 | /* | |
1097 | * Uncache all the pages in an inode that are marked PG_fscache, assuming them | |
1098 | * to be associated with the given cookie. | |
1099 | */ | |
1100 | void __fscache_uncache_all_inode_pages(struct fscache_cookie *cookie, | |
1101 | struct inode *inode) | |
1102 | { | |
1103 | struct address_space *mapping = inode->i_mapping; | |
1104 | struct pagevec pvec; | |
1105 | pgoff_t next; | |
1106 | int i; | |
1107 | ||
1108 | _enter("%p,%p", cookie, inode); | |
1109 | ||
1110 | if (!mapping || mapping->nrpages == 0) { | |
1111 | _leave(" [no pages]"); | |
1112 | return; | |
1113 | } | |
1114 | ||
1115 | pagevec_init(&pvec, 0); | |
1116 | next = 0; | |
1117 | do { | |
1118 | if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) | |
1119 | break; | |
1120 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
1121 | struct page *page = pvec.pages[i]; | |
1122 | next = page->index; | |
1123 | if (PageFsCache(page)) { | |
1124 | __fscache_wait_on_page_write(cookie, page); | |
1125 | __fscache_uncache_page(cookie, page); | |
1126 | } | |
1127 | } | |
1128 | pagevec_release(&pvec); | |
1129 | cond_resched(); | |
1130 | } while (++next); | |
1131 | ||
1132 | _leave(""); | |
1133 | } | |
1134 | EXPORT_SYMBOL(__fscache_uncache_all_inode_pages); |