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