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Merge tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm...
[linux-2.6.git] / fs / fscache / page.c
blob7f5c658af755f9b43296c1dacfab5def788c4a1c
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_stat(&fscache_n_cop_attr_changed);
168 ret = object->cache->ops->attr_changed(object);
169 fscache_stat_d(&fscache_n_cop_attr_changed);
170 if (ret < 0)
171 fscache_abort_object(object);
172 }
173
174 fscache_op_complete(op, true);
175 _leave("");
176 }
177
178 /*
179 * notification that the attributes on an object have changed
180 */
181 int __fscache_attr_changed(struct fscache_cookie *cookie)
182 {
183 struct fscache_operation *op;
184 struct fscache_object *object;
185 bool wake_cookie;
186
187 _enter("%p", cookie);
188
189 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
190
191 fscache_stat(&fscache_n_attr_changed);
192
193 op = kzalloc(sizeof(*op), GFP_KERNEL);
194 if (!op) {
195 fscache_stat(&fscache_n_attr_changed_nomem);
196 _leave(" = -ENOMEM");
197 return -ENOMEM;
198 }
199
200 fscache_operation_init(op, fscache_attr_changed_op, NULL);
201 op->flags = FSCACHE_OP_ASYNC |
202 (1 << FSCACHE_OP_EXCLUSIVE) |
203 (1 << FSCACHE_OP_UNUSE_COOKIE);
204
205 spin_lock(&cookie->lock);
206
207 if (!fscache_cookie_enabled(cookie) ||
208 hlist_empty(&cookie->backing_objects))
209 goto nobufs;
210 object = hlist_entry(cookie->backing_objects.first,
211 struct fscache_object, cookie_link);
212
213 __fscache_use_cookie(cookie);
214 if (fscache_submit_exclusive_op(object, op) < 0)
215 goto nobufs;
216 spin_unlock(&cookie->lock);
217 fscache_stat(&fscache_n_attr_changed_ok);
218 fscache_put_operation(op);
219 _leave(" = 0");
220 return 0;
221
222 nobufs:
223 wake_cookie = __fscache_unuse_cookie(cookie);
224 spin_unlock(&cookie->lock);
225 kfree(op);
226 if (wake_cookie)
227 __fscache_wake_unused_cookie(cookie);
228 fscache_stat(&fscache_n_attr_changed_nobufs);
229 _leave(" = %d", -ENOBUFS);
230 return -ENOBUFS;
231 }
232 EXPORT_SYMBOL(__fscache_attr_changed);
233
234 /*
235 * release a retrieval op reference
236 */
237 static void fscache_release_retrieval_op(struct fscache_operation *_op)
238 {
239 struct fscache_retrieval *op =
240 container_of(_op, struct fscache_retrieval, op);
241
242 _enter("{OP%x}", op->op.debug_id);
243
244 ASSERTCMP(atomic_read(&op->n_pages), ==, 0);
245
246 fscache_hist(fscache_retrieval_histogram, op->start_time);
247 if (op->context)
248 fscache_put_context(op->op.object->cookie, op->context);
249
250 _leave("");
251 }
252
253 /*
254 * allocate a retrieval op
255 */
256 static struct fscache_retrieval *fscache_alloc_retrieval(
257 struct fscache_cookie *cookie,
258 struct address_space *mapping,
259 fscache_rw_complete_t end_io_func,
260 void *context)
261 {
262 struct fscache_retrieval *op;
263
264 /* allocate a retrieval operation and attempt to submit it */
265 op = kzalloc(sizeof(*op), GFP_NOIO);
266 if (!op) {
267 fscache_stat(&fscache_n_retrievals_nomem);
268 return NULL;
269 }
270
271 fscache_operation_init(&op->op, NULL, fscache_release_retrieval_op);
272 op->op.flags = FSCACHE_OP_MYTHREAD |
273 (1UL << FSCACHE_OP_WAITING) |
274 (1UL << FSCACHE_OP_UNUSE_COOKIE);
275 op->mapping = mapping;
276 op->end_io_func = end_io_func;
277 op->context = context;
278 op->start_time = jiffies;
279 INIT_LIST_HEAD(&op->to_do);
280 return op;
281 }
282
283 /*
284 * wait for a deferred lookup to complete
285 */
286 int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie)
287 {
288 unsigned long jif;
289
290 _enter("");
291
292 if (!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)) {
293 _leave(" = 0 [imm]");
294 return 0;
295 }
296
297 fscache_stat(&fscache_n_retrievals_wait);
298
299 jif = jiffies;
300 if (wait_on_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP,
301 fscache_wait_bit_interruptible,
302 TASK_INTERRUPTIBLE) != 0) {
303 fscache_stat(&fscache_n_retrievals_intr);
304 _leave(" = -ERESTARTSYS");
305 return -ERESTARTSYS;
306 }
307
308 ASSERT(!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags));
309
310 smp_rmb();
311 fscache_hist(fscache_retrieval_delay_histogram, jif);
312 _leave(" = 0 [dly]");
313 return 0;
314 }
315
316 /*
317 * Handle cancellation of a pending retrieval op
318 */
319 static void fscache_do_cancel_retrieval(struct fscache_operation *_op)
320 {
321 struct fscache_retrieval *op =
322 container_of(_op, struct fscache_retrieval, op);
323
324 atomic_set(&op->n_pages, 0);
325 }
326
327 /*
328 * wait for an object to become active (or dead)
329 */
330 int fscache_wait_for_operation_activation(struct fscache_object *object,
331 struct fscache_operation *op,
332 atomic_t *stat_op_waits,
333 atomic_t *stat_object_dead,
334 void (*do_cancel)(struct fscache_operation *))
335 {
336 int ret;
337
338 if (!test_bit(FSCACHE_OP_WAITING, &op->flags))
339 goto check_if_dead;
340
341 _debug(">>> WT");
342 if (stat_op_waits)
343 fscache_stat(stat_op_waits);
344 if (wait_on_bit(&op->flags, FSCACHE_OP_WAITING,
345 fscache_wait_bit_interruptible,
346 TASK_INTERRUPTIBLE) != 0) {
347 ret = fscache_cancel_op(op, do_cancel);
348 if (ret == 0)
349 return -ERESTARTSYS;
350
351 /* it's been removed from the pending queue by another party,
352 * so we should get to run shortly */
353 wait_on_bit(&op->flags, FSCACHE_OP_WAITING,
354 fscache_wait_bit, TASK_UNINTERRUPTIBLE);
355 }
356 _debug("<<< GO");
357
358 check_if_dead:
359 if (op->state == FSCACHE_OP_ST_CANCELLED) {
360 if (stat_object_dead)
361 fscache_stat(stat_object_dead);
362 _leave(" = -ENOBUFS [cancelled]");
363 return -ENOBUFS;
364 }
365 if (unlikely(fscache_object_is_dead(object))) {
366 pr_err("%s() = -ENOBUFS [obj dead %d]\n", __func__, op->state);
367 fscache_cancel_op(op, do_cancel);
368 if (stat_object_dead)
369 fscache_stat(stat_object_dead);
370 return -ENOBUFS;
371 }
372 return 0;
373 }
374
375 /*
376 * read a page from the cache or allocate a block in which to store it
377 * - we return:
378 * -ENOMEM - out of memory, nothing done
379 * -ERESTARTSYS - interrupted
380 * -ENOBUFS - no backing object available in which to cache the block
381 * -ENODATA - no data available in the backing object for this block
382 * 0 - dispatched a read - it'll call end_io_func() when finished
383 */
384 int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
385 struct page *page,
386 fscache_rw_complete_t end_io_func,
387 void *context,
388 gfp_t gfp)
389 {
390 struct fscache_retrieval *op;
391 struct fscache_object *object;
392 bool wake_cookie = false;
393 int ret;
394
395 _enter("%p,%p,,,", cookie, page);
396
397 fscache_stat(&fscache_n_retrievals);
398
399 if (hlist_empty(&cookie->backing_objects))
400 goto nobufs;
401
402 if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
403 _leave(" = -ENOBUFS [invalidating]");
404 return -ENOBUFS;
405 }
406
407 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
408 ASSERTCMP(page, !=, NULL);
409
410 if (fscache_wait_for_deferred_lookup(cookie) < 0)
411 return -ERESTARTSYS;
412
413 op = fscache_alloc_retrieval(cookie, page->mapping,
414 end_io_func, context);
415 if (!op) {
416 _leave(" = -ENOMEM");
417 return -ENOMEM;
418 }
419 atomic_set(&op->n_pages, 1);
420
421 spin_lock(&cookie->lock);
422
423 if (!fscache_cookie_enabled(cookie) ||
424 hlist_empty(&cookie->backing_objects))
425 goto nobufs_unlock;
426 object = hlist_entry(cookie->backing_objects.first,
427 struct fscache_object, cookie_link);
428
429 ASSERT(test_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags));
430
431 __fscache_use_cookie(cookie);
432 atomic_inc(&object->n_reads);
433 __set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
434
435 if (fscache_submit_op(object, &op->op) < 0)
436 goto nobufs_unlock_dec;
437 spin_unlock(&cookie->lock);
438
439 fscache_stat(&fscache_n_retrieval_ops);
440
441 /* pin the netfs read context in case we need to do the actual netfs
442 * read because we've encountered a cache read failure */
443 fscache_get_context(object->cookie, op->context);
444
445 /* we wait for the operation to become active, and then process it
446 * *here*, in this thread, and not in the thread pool */
447 ret = fscache_wait_for_operation_activation(
448 object, &op->op,
449 __fscache_stat(&fscache_n_retrieval_op_waits),
450 __fscache_stat(&fscache_n_retrievals_object_dead),
451 fscache_do_cancel_retrieval);
452 if (ret < 0)
453 goto error;
454
455 /* ask the cache to honour the operation */
456 if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) {
457 fscache_stat(&fscache_n_cop_allocate_page);
458 ret = object->cache->ops->allocate_page(op, page, gfp);
459 fscache_stat_d(&fscache_n_cop_allocate_page);
460 if (ret == 0)
461 ret = -ENODATA;
462 } else {
463 fscache_stat(&fscache_n_cop_read_or_alloc_page);
464 ret = object->cache->ops->read_or_alloc_page(op, page, gfp);
465 fscache_stat_d(&fscache_n_cop_read_or_alloc_page);
466 }
467
468 error:
469 if (ret == -ENOMEM)
470 fscache_stat(&fscache_n_retrievals_nomem);
471 else if (ret == -ERESTARTSYS)
472 fscache_stat(&fscache_n_retrievals_intr);
473 else if (ret == -ENODATA)
474 fscache_stat(&fscache_n_retrievals_nodata);
475 else if (ret < 0)
476 fscache_stat(&fscache_n_retrievals_nobufs);
477 else
478 fscache_stat(&fscache_n_retrievals_ok);
479
480 fscache_put_retrieval(op);
481 _leave(" = %d", ret);
482 return ret;
483
484 nobufs_unlock_dec:
485 atomic_dec(&object->n_reads);
486 wake_cookie = __fscache_unuse_cookie(cookie);
487 nobufs_unlock:
488 spin_unlock(&cookie->lock);
489 if (wake_cookie)
490 __fscache_wake_unused_cookie(cookie);
491 kfree(op);
492 nobufs:
493 fscache_stat(&fscache_n_retrievals_nobufs);
494 _leave(" = -ENOBUFS");
495 return -ENOBUFS;
496 }
497 EXPORT_SYMBOL(__fscache_read_or_alloc_page);
498
499 /*
500 * read a list of page from the cache or allocate a block in which to store
501 * them
502 * - we return:
503 * -ENOMEM - out of memory, some pages may be being read
504 * -ERESTARTSYS - interrupted, some pages may be being read
505 * -ENOBUFS - no backing object or space available in which to cache any
506 * pages not being read
507 * -ENODATA - no data available in the backing object for some or all of
508 * the pages
509 * 0 - dispatched a read on all pages
510 *
511 * end_io_func() will be called for each page read from the cache as it is
512 * finishes being read
513 *
514 * any pages for which a read is dispatched will be removed from pages and
515 * nr_pages
516 */
517 int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
518 struct address_space *mapping,
519 struct list_head *pages,
520 unsigned *nr_pages,
521 fscache_rw_complete_t end_io_func,
522 void *context,
523 gfp_t gfp)
524 {
525 struct fscache_retrieval *op;
526 struct fscache_object *object;
527 bool wake_cookie = false;
528 int ret;
529
530 _enter("%p,,%d,,,", cookie, *nr_pages);
531
532 fscache_stat(&fscache_n_retrievals);
533
534 if (hlist_empty(&cookie->backing_objects))
535 goto nobufs;
536
537 if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
538 _leave(" = -ENOBUFS [invalidating]");
539 return -ENOBUFS;
540 }
541
542 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
543 ASSERTCMP(*nr_pages, >, 0);
544 ASSERT(!list_empty(pages));
545
546 if (fscache_wait_for_deferred_lookup(cookie) < 0)
547 return -ERESTARTSYS;
548
549 op = fscache_alloc_retrieval(cookie, mapping, end_io_func, context);
550 if (!op)
551 return -ENOMEM;
552 atomic_set(&op->n_pages, *nr_pages);
553
554 spin_lock(&cookie->lock);
555
556 if (!fscache_cookie_enabled(cookie) ||
557 hlist_empty(&cookie->backing_objects))
558 goto nobufs_unlock;
559 object = hlist_entry(cookie->backing_objects.first,
560 struct fscache_object, cookie_link);
561
562 __fscache_use_cookie(cookie);
563 atomic_inc(&object->n_reads);
564 __set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
565
566 if (fscache_submit_op(object, &op->op) < 0)
567 goto nobufs_unlock_dec;
568 spin_unlock(&cookie->lock);
569
570 fscache_stat(&fscache_n_retrieval_ops);
571
572 /* pin the netfs read context in case we need to do the actual netfs
573 * read because we've encountered a cache read failure */
574 fscache_get_context(object->cookie, op->context);
575
576 /* we wait for the operation to become active, and then process it
577 * *here*, in this thread, and not in the thread pool */
578 ret = fscache_wait_for_operation_activation(
579 object, &op->op,
580 __fscache_stat(&fscache_n_retrieval_op_waits),
581 __fscache_stat(&fscache_n_retrievals_object_dead),
582 fscache_do_cancel_retrieval);
583 if (ret < 0)
584 goto error;
585
586 /* ask the cache to honour the operation */
587 if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) {
588 fscache_stat(&fscache_n_cop_allocate_pages);
589 ret = object->cache->ops->allocate_pages(
590 op, pages, nr_pages, gfp);
591 fscache_stat_d(&fscache_n_cop_allocate_pages);
592 } else {
593 fscache_stat(&fscache_n_cop_read_or_alloc_pages);
594 ret = object->cache->ops->read_or_alloc_pages(
595 op, pages, nr_pages, gfp);
596 fscache_stat_d(&fscache_n_cop_read_or_alloc_pages);
597 }
598
599 error:
600 if (ret == -ENOMEM)
601 fscache_stat(&fscache_n_retrievals_nomem);
602 else if (ret == -ERESTARTSYS)
603 fscache_stat(&fscache_n_retrievals_intr);
604 else if (ret == -ENODATA)
605 fscache_stat(&fscache_n_retrievals_nodata);
606 else if (ret < 0)
607 fscache_stat(&fscache_n_retrievals_nobufs);
608 else
609 fscache_stat(&fscache_n_retrievals_ok);
610
611 fscache_put_retrieval(op);
612 _leave(" = %d", ret);
613 return ret;
614
615 nobufs_unlock_dec:
616 atomic_dec(&object->n_reads);
617 wake_cookie = __fscache_unuse_cookie(cookie);
618 nobufs_unlock:
619 spin_unlock(&cookie->lock);
620 kfree(op);
621 if (wake_cookie)
622 __fscache_wake_unused_cookie(cookie);
623 nobufs:
624 fscache_stat(&fscache_n_retrievals_nobufs);
625 _leave(" = -ENOBUFS");
626 return -ENOBUFS;
627 }
628 EXPORT_SYMBOL(__fscache_read_or_alloc_pages);
629
630 /*
631 * allocate a block in the cache on which to store a page
632 * - we return:
633 * -ENOMEM - out of memory, nothing done
634 * -ERESTARTSYS - interrupted
635 * -ENOBUFS - no backing object available in which to cache the block
636 * 0 - block allocated
637 */
638 int __fscache_alloc_page(struct fscache_cookie *cookie,
639 struct page *page,
640 gfp_t gfp)
641 {
642 struct fscache_retrieval *op;
643 struct fscache_object *object;
644 bool wake_cookie = false;
645 int ret;
646
647 _enter("%p,%p,,,", cookie, page);
648
649 fscache_stat(&fscache_n_allocs);
650
651 if (hlist_empty(&cookie->backing_objects))
652 goto nobufs;
653
654 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
655 ASSERTCMP(page, !=, NULL);
656
657 if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
658 _leave(" = -ENOBUFS [invalidating]");
659 return -ENOBUFS;
660 }
661
662 if (fscache_wait_for_deferred_lookup(cookie) < 0)
663 return -ERESTARTSYS;
664
665 op = fscache_alloc_retrieval(cookie, page->mapping, NULL, NULL);
666 if (!op)
667 return -ENOMEM;
668 atomic_set(&op->n_pages, 1);
669
670 spin_lock(&cookie->lock);
671
672 if (!fscache_cookie_enabled(cookie) ||
673 hlist_empty(&cookie->backing_objects))
674 goto nobufs_unlock;
675 object = hlist_entry(cookie->backing_objects.first,
676 struct fscache_object, cookie_link);
677
678 __fscache_use_cookie(cookie);
679 if (fscache_submit_op(object, &op->op) < 0)
680 goto nobufs_unlock_dec;
681 spin_unlock(&cookie->lock);
682
683 fscache_stat(&fscache_n_alloc_ops);
684
685 ret = fscache_wait_for_operation_activation(
686 object, &op->op,
687 __fscache_stat(&fscache_n_alloc_op_waits),
688 __fscache_stat(&fscache_n_allocs_object_dead),
689 fscache_do_cancel_retrieval);
690 if (ret < 0)
691 goto error;
692
693 /* ask the cache to honour the operation */
694 fscache_stat(&fscache_n_cop_allocate_page);
695 ret = object->cache->ops->allocate_page(op, page, gfp);
696 fscache_stat_d(&fscache_n_cop_allocate_page);
697
698 error:
699 if (ret == -ERESTARTSYS)
700 fscache_stat(&fscache_n_allocs_intr);
701 else if (ret < 0)
702 fscache_stat(&fscache_n_allocs_nobufs);
703 else
704 fscache_stat(&fscache_n_allocs_ok);
705
706 fscache_put_retrieval(op);
707 _leave(" = %d", ret);
708 return ret;
709
710 nobufs_unlock_dec:
711 wake_cookie = __fscache_unuse_cookie(cookie);
712 nobufs_unlock:
713 spin_unlock(&cookie->lock);
714 kfree(op);
715 if (wake_cookie)
716 __fscache_wake_unused_cookie(cookie);
717 nobufs:
718 fscache_stat(&fscache_n_allocs_nobufs);
719 _leave(" = -ENOBUFS");
720 return -ENOBUFS;
721 }
722 EXPORT_SYMBOL(__fscache_alloc_page);
723
724 /*
725 * Unmark pages allocate in the readahead code path (via:
726 * fscache_readpages_or_alloc) after delegating to the base filesystem
727 */
728 void __fscache_readpages_cancel(struct fscache_cookie *cookie,
729 struct list_head *pages)
730 {
731 struct page *page;
732
733 list_for_each_entry(page, pages, lru) {
734 if (PageFsCache(page))
735 __fscache_uncache_page(cookie, page);
736 }
737 }
738 EXPORT_SYMBOL(__fscache_readpages_cancel);
739
740 /*
741 * release a write op reference
742 */
743 static void fscache_release_write_op(struct fscache_operation *_op)
744 {
745 _enter("{OP%x}", _op->debug_id);
746 }
747
748 /*
749 * perform the background storage of a page into the cache
750 */
751 static void fscache_write_op(struct fscache_operation *_op)
752 {
753 struct fscache_storage *op =
754 container_of(_op, struct fscache_storage, op);
755 struct fscache_object *object = op->op.object;
756 struct fscache_cookie *cookie;
757 struct page *page;
758 unsigned n;
759 void *results[1];
760 int ret;
761
762 _enter("{OP%x,%d}", op->op.debug_id, atomic_read(&op->op.usage));
763
764 spin_lock(&object->lock);
765 cookie = object->cookie;
766
767 if (!fscache_object_is_active(object)) {
768 /* If we get here, then the on-disk cache object likely longer
769 * exists, so we should just cancel this write operation.
770 */
771 spin_unlock(&object->lock);
772 fscache_op_complete(&op->op, false);
773 _leave(" [inactive]");
774 return;
775 }
776
777 if (!cookie) {
778 /* If we get here, then the cookie belonging to the object was
779 * detached, probably by the cookie being withdrawn due to
780 * memory pressure, which means that the pages we might write
781 * to the cache from no longer exist - therefore, we can just
782 * cancel this write operation.
783 */
784 spin_unlock(&object->lock);
785 fscache_op_complete(&op->op, false);
786 _leave(" [cancel] op{f=%lx s=%u} obj{s=%s f=%lx}",
787 _op->flags, _op->state, object->state->short_name,
788 object->flags);
789 return;
790 }
791
792 spin_lock(&cookie->stores_lock);
793
794 fscache_stat(&fscache_n_store_calls);
795
796 /* find a page to store */
797 page = NULL;
798 n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0, 1,
799 FSCACHE_COOKIE_PENDING_TAG);
800 if (n != 1)
801 goto superseded;
802 page = results[0];
803 _debug("gang %d [%lx]", n, page->index);
804 if (page->index > op->store_limit) {
805 fscache_stat(&fscache_n_store_pages_over_limit);
806 goto superseded;
807 }
808
809 radix_tree_tag_set(&cookie->stores, page->index,
810 FSCACHE_COOKIE_STORING_TAG);
811 radix_tree_tag_clear(&cookie->stores, page->index,
812 FSCACHE_COOKIE_PENDING_TAG);
813
814 spin_unlock(&cookie->stores_lock);
815 spin_unlock(&object->lock);
816
817 fscache_stat(&fscache_n_store_pages);
818 fscache_stat(&fscache_n_cop_write_page);
819 ret = object->cache->ops->write_page(op, page);
820 fscache_stat_d(&fscache_n_cop_write_page);
821 fscache_end_page_write(object, page);
822 if (ret < 0) {
823 fscache_abort_object(object);
824 fscache_op_complete(&op->op, true);
825 } else {
826 fscache_enqueue_operation(&op->op);
827 }
828
829 _leave("");
830 return;
831
832 superseded:
833 /* this writer is going away and there aren't any more things to
834 * write */
835 _debug("cease");
836 spin_unlock(&cookie->stores_lock);
837 clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
838 spin_unlock(&object->lock);
839 fscache_op_complete(&op->op, true);
840 _leave("");
841 }
842
843 /*
844 * Clear the pages pending writing for invalidation
845 */
846 void fscache_invalidate_writes(struct fscache_cookie *cookie)
847 {
848 struct page *page;
849 void *results[16];
850 int n, i;
851
852 _enter("");
853
854 for (;;) {
855 spin_lock(&cookie->stores_lock);
856 n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0,
857 ARRAY_SIZE(results),
858 FSCACHE_COOKIE_PENDING_TAG);
859 if (n == 0) {
860 spin_unlock(&cookie->stores_lock);
861 break;
862 }
863
864 for (i = n - 1; i >= 0; i--) {
865 page = results[i];
866 radix_tree_delete(&cookie->stores, page->index);
867 }
868
869 spin_unlock(&cookie->stores_lock);
870
871 for (i = n - 1; i >= 0; i--)
872 page_cache_release(results[i]);
873 }
874
875 _leave("");
876 }
877
878 /*
879 * request a page be stored in the cache
880 * - returns:
881 * -ENOMEM - out of memory, nothing done
882 * -ENOBUFS - no backing object available in which to cache the page
883 * 0 - dispatched a write - it'll call end_io_func() when finished
884 *
885 * if the cookie still has a backing object at this point, that object can be
886 * in one of a few states with respect to storage processing:
887 *
888 * (1) negative lookup, object not yet created (FSCACHE_COOKIE_CREATING is
889 * set)
890 *
891 * (a) no writes yet
892 *
893 * (b) writes deferred till post-creation (mark page for writing and
894 * return immediately)
895 *
896 * (2) negative lookup, object created, initial fill being made from netfs
897 *
898 * (a) fill point not yet reached this page (mark page for writing and
899 * return)
900 *
901 * (b) fill point passed this page (queue op to store this page)
902 *
903 * (3) object extant (queue op to store this page)
904 *
905 * any other state is invalid
906 */
907 int __fscache_write_page(struct fscache_cookie *cookie,
908 struct page *page,
909 gfp_t gfp)
910 {
911 struct fscache_storage *op;
912 struct fscache_object *object;
913 bool wake_cookie = false;
914 int ret;
915
916 _enter("%p,%x,", cookie, (u32) page->flags);
917
918 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
919 ASSERT(PageFsCache(page));
920
921 fscache_stat(&fscache_n_stores);
922
923 if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
924 _leave(" = -ENOBUFS [invalidating]");
925 return -ENOBUFS;
926 }
927
928 op = kzalloc(sizeof(*op), GFP_NOIO | __GFP_NOMEMALLOC | __GFP_NORETRY);
929 if (!op)
930 goto nomem;
931
932 fscache_operation_init(&op->op, fscache_write_op,
933 fscache_release_write_op);
934 op->op.flags = FSCACHE_OP_ASYNC |
935 (1 << FSCACHE_OP_WAITING) |
936 (1 << FSCACHE_OP_UNUSE_COOKIE);
937
938 ret = radix_tree_maybe_preload(gfp & ~__GFP_HIGHMEM);
939 if (ret < 0)
940 goto nomem_free;
941
942 ret = -ENOBUFS;
943 spin_lock(&cookie->lock);
944
945 if (!fscache_cookie_enabled(cookie) ||
946 hlist_empty(&cookie->backing_objects))
947 goto nobufs;
948 object = hlist_entry(cookie->backing_objects.first,
949 struct fscache_object, cookie_link);
950 if (test_bit(FSCACHE_IOERROR, &object->cache->flags))
951 goto nobufs;
952
953 /* add the page to the pending-storage radix tree on the backing
954 * object */
955 spin_lock(&object->lock);
956 spin_lock(&cookie->stores_lock);
957
958 _debug("store limit %llx", (unsigned long long) object->store_limit);
959
960 ret = radix_tree_insert(&cookie->stores, page->index, page);
961 if (ret < 0) {
962 if (ret == -EEXIST)
963 goto already_queued;
964 _debug("insert failed %d", ret);
965 goto nobufs_unlock_obj;
966 }
967
968 radix_tree_tag_set(&cookie->stores, page->index,
969 FSCACHE_COOKIE_PENDING_TAG);
970 page_cache_get(page);
971
972 /* we only want one writer at a time, but we do need to queue new
973 * writers after exclusive ops */
974 if (test_and_set_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags))
975 goto already_pending;
976
977 spin_unlock(&cookie->stores_lock);
978 spin_unlock(&object->lock);
979
980 op->op.debug_id = atomic_inc_return(&fscache_op_debug_id);
981 op->store_limit = object->store_limit;
982
983 __fscache_use_cookie(cookie);
984 if (fscache_submit_op(object, &op->op) < 0)
985 goto submit_failed;
986
987 spin_unlock(&cookie->lock);
988 radix_tree_preload_end();
989 fscache_stat(&fscache_n_store_ops);
990 fscache_stat(&fscache_n_stores_ok);
991
992 /* the work queue now carries its own ref on the object */
993 fscache_put_operation(&op->op);
994 _leave(" = 0");
995 return 0;
996
997 already_queued:
998 fscache_stat(&fscache_n_stores_again);
999 already_pending:
1000 spin_unlock(&cookie->stores_lock);
1001 spin_unlock(&object->lock);
1002 spin_unlock(&cookie->lock);
1003 radix_tree_preload_end();
1004 kfree(op);
1005 fscache_stat(&fscache_n_stores_ok);
1006 _leave(" = 0");
1007 return 0;
1008
1009 submit_failed:
1010 spin_lock(&cookie->stores_lock);
1011 radix_tree_delete(&cookie->stores, page->index);
1012 spin_unlock(&cookie->stores_lock);
1013 wake_cookie = __fscache_unuse_cookie(cookie);
1014 page_cache_release(page);
1015 ret = -ENOBUFS;
1016 goto nobufs;
1017
1018 nobufs_unlock_obj:
1019 spin_unlock(&cookie->stores_lock);
1020 spin_unlock(&object->lock);
1021 nobufs:
1022 spin_unlock(&cookie->lock);
1023 radix_tree_preload_end();
1024 kfree(op);
1025 if (wake_cookie)
1026 __fscache_wake_unused_cookie(cookie);
1027 fscache_stat(&fscache_n_stores_nobufs);
1028 _leave(" = -ENOBUFS");
1029 return -ENOBUFS;
1030
1031 nomem_free:
1032 kfree(op);
1033 nomem:
1034 fscache_stat(&fscache_n_stores_oom);
1035 _leave(" = -ENOMEM");
1036 return -ENOMEM;
1037 }
1038 EXPORT_SYMBOL(__fscache_write_page);
1039
1040 /*
1041 * remove a page from the cache
1042 */
1043 void __fscache_uncache_page(struct fscache_cookie *cookie, struct page *page)
1044 {
1045 struct fscache_object *object;
1046
1047 _enter(",%p", page);
1048
1049 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
1050 ASSERTCMP(page, !=, NULL);
1051
1052 fscache_stat(&fscache_n_uncaches);
1053
1054 /* cache withdrawal may beat us to it */
1055 if (!PageFsCache(page))
1056 goto done;
1057
1058 /* get the object */
1059 spin_lock(&cookie->lock);
1060
1061 if (hlist_empty(&cookie->backing_objects)) {
1062 ClearPageFsCache(page);
1063 goto done_unlock;
1064 }
1065
1066 object = hlist_entry(cookie->backing_objects.first,
1067 struct fscache_object, cookie_link);
1068
1069 /* there might now be stuff on disk we could read */
1070 clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
1071
1072 /* only invoke the cache backend if we managed to mark the page
1073 * uncached here; this deals with synchronisation vs withdrawal */
1074 if (TestClearPageFsCache(page) &&
1075 object->cache->ops->uncache_page) {
1076 /* the cache backend releases the cookie lock */
1077 fscache_stat(&fscache_n_cop_uncache_page);
1078 object->cache->ops->uncache_page(object, page);
1079 fscache_stat_d(&fscache_n_cop_uncache_page);
1080 goto done;
1081 }
1082
1083 done_unlock:
1084 spin_unlock(&cookie->lock);
1085 done:
1086 _leave("");
1087 }
1088 EXPORT_SYMBOL(__fscache_uncache_page);
1089
1090 /**
1091 * fscache_mark_page_cached - Mark a page as being cached
1092 * @op: The retrieval op pages are being marked for
1093 * @page: The page to be marked
1094 *
1095 * Mark a netfs page as being cached. After this is called, the netfs
1096 * must call fscache_uncache_page() to remove the mark.
1097 */
1098 void fscache_mark_page_cached(struct fscache_retrieval *op, struct page *page)
1099 {
1100 struct fscache_cookie *cookie = op->op.object->cookie;
1101
1102 #ifdef CONFIG_FSCACHE_STATS
1103 atomic_inc(&fscache_n_marks);
1104 #endif
1105
1106 _debug("- mark %p{%lx}", page, page->index);
1107 if (TestSetPageFsCache(page)) {
1108 static bool once_only;
1109 if (!once_only) {
1110 once_only = true;
1111 printk(KERN_WARNING "FS-Cache:"
1112 " Cookie type %s marked page %lx"
1113 " multiple times\n",
1114 cookie->def->name, page->index);
1115 }
1116 }
1117
1118 if (cookie->def->mark_page_cached)
1119 cookie->def->mark_page_cached(cookie->netfs_data,
1120 op->mapping, page);
1121 }
1122 EXPORT_SYMBOL(fscache_mark_page_cached);
1123
1124 /**
1125 * fscache_mark_pages_cached - Mark pages as being cached
1126 * @op: The retrieval op pages are being marked for
1127 * @pagevec: The pages to be marked
1128 *
1129 * Mark a bunch of netfs pages as being cached. After this is called,
1130 * the netfs must call fscache_uncache_page() to remove the mark.
1131 */
1132 void fscache_mark_pages_cached(struct fscache_retrieval *op,
1133 struct pagevec *pagevec)
1134 {
1135 unsigned long loop;
1136
1137 for (loop = 0; loop < pagevec->nr; loop++)
1138 fscache_mark_page_cached(op, pagevec->pages[loop]);
1139
1140 pagevec_reinit(pagevec);
1141 }
1142 EXPORT_SYMBOL(fscache_mark_pages_cached);
1143
1144 /*
1145 * Uncache all the pages in an inode that are marked PG_fscache, assuming them
1146 * to be associated with the given cookie.
1147 */
1148 void __fscache_uncache_all_inode_pages(struct fscache_cookie *cookie,
1149 struct inode *inode)
1150 {
1151 struct address_space *mapping = inode->i_mapping;
1152 struct pagevec pvec;
1153 pgoff_t next;
1154 int i;
1155
1156 _enter("%p,%p", cookie, inode);
1157
1158 if (!mapping || mapping->nrpages == 0) {
1159 _leave(" [no pages]");
1160 return;
1161 }
1162
1163 pagevec_init(&pvec, 0);
1164 next = 0;
1165 do {
1166 if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE))
1167 break;
1168 for (i = 0; i < pagevec_count(&pvec); i++) {
1169 struct page *page = pvec.pages[i];
1170 next = page->index;
1171 if (PageFsCache(page)) {
1172 __fscache_wait_on_page_write(cookie, page);
1173 __fscache_uncache_page(cookie, page);
1174 }
1175 }
1176 pagevec_release(&pvec);
1177 cond_resched();
1178 } while (++next);
1179
1180 _leave("");
1181 }
1182 EXPORT_SYMBOL(__fscache_uncache_all_inode_pages);
Linus' kernel tree