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