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FS-Cache: Handle pages pending storage that get evicted under OOM conditions
[linux-2.6/x86.git] / fs / fscache / page.c
blobfc76798bd968f1bf9b9ebe4bb94d0a206d12d914
1 /* Cache page management and data I/O routines
2 *
3 * Copyright (C) 2004-2008 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12 #define FSCACHE_DEBUG_LEVEL PAGE
13 #include <linux/module.h>
14 #include <linux/fscache-cache.h>
15 #include <linux/buffer_head.h>
16 #include <linux/pagevec.h>
17 #include "internal.h"
18
19 /*
20 * check to see if a page is being written to the cache
21 */
22 bool __fscache_check_page_write(struct fscache_cookie *cookie, struct page *page)
23 {
24 void *val;
25
26 rcu_read_lock();
27 val = radix_tree_lookup(&cookie->stores, page->index);
28 rcu_read_unlock();
29
30 return val != NULL;
31 }
32 EXPORT_SYMBOL(__fscache_check_page_write);
33
34 /*
35 * wait for a page to finish being written to the cache
36 */
37 void __fscache_wait_on_page_write(struct fscache_cookie *cookie, struct page *page)
38 {
39 wait_queue_head_t *wq = bit_waitqueue(&cookie->flags, 0);
40
41 wait_event(*wq, !__fscache_check_page_write(cookie, page));
42 }
43 EXPORT_SYMBOL(__fscache_wait_on_page_write);
44
45 /*
46 * decide whether a page can be released, possibly by cancelling a store to it
47 * - we're allowed to sleep if __GFP_WAIT is flagged
48 */
49 bool __fscache_maybe_release_page(struct fscache_cookie *cookie,
50 struct page *page,
51 gfp_t gfp)
52 {
53 struct page *xpage;
54 void *val;
55
56 _enter("%p,%p,%x", cookie, page, gfp);
57
58 rcu_read_lock();
59 val = radix_tree_lookup(&cookie->stores, page->index);
60 if (!val) {
61 rcu_read_unlock();
62 fscache_stat(&fscache_n_store_vmscan_not_storing);
63 __fscache_uncache_page(cookie, page);
64 return true;
65 }
66
67 /* see if the page is actually undergoing storage - if so we can't get
68 * rid of it till the cache has finished with it */
69 if (radix_tree_tag_get(&cookie->stores, page->index,
70 FSCACHE_COOKIE_STORING_TAG)) {
71 rcu_read_unlock();
72 goto page_busy;
73 }
74
75 /* the page is pending storage, so we attempt to cancel the store and
76 * discard the store request so that the page can be reclaimed */
77 spin_lock(&cookie->stores_lock);
78 rcu_read_unlock();
79
80 if (radix_tree_tag_get(&cookie->stores, page->index,
81 FSCACHE_COOKIE_STORING_TAG)) {
82 /* the page started to undergo storage whilst we were looking,
83 * so now we can only wait or return */
84 spin_unlock(&cookie->stores_lock);
85 goto page_busy;
86 }
87
88 xpage = radix_tree_delete(&cookie->stores, page->index);
89 spin_unlock(&cookie->stores_lock);
90
91 if (xpage) {
92 fscache_stat(&fscache_n_store_vmscan_cancelled);
93 fscache_stat(&fscache_n_store_radix_deletes);
94 ASSERTCMP(xpage, ==, page);
95 } else {
96 fscache_stat(&fscache_n_store_vmscan_gone);
97 }
98
99 wake_up_bit(&cookie->flags, 0);
100 if (xpage)
101 page_cache_release(xpage);
102 __fscache_uncache_page(cookie, page);
103 return true;
104
105 page_busy:
106 /* we might want to wait here, but that could deadlock the allocator as
107 * the slow-work threads writing to the cache may all end up sleeping
108 * on memory allocation */
109 fscache_stat(&fscache_n_store_vmscan_busy);
110 return false;
111 }
112 EXPORT_SYMBOL(__fscache_maybe_release_page);
113
114 /*
115 * note that a page has finished being written to the cache
116 */
117 static void fscache_end_page_write(struct fscache_object *object,
118 struct page *page)
119 {
120 struct fscache_cookie *cookie;
121 struct page *xpage = NULL;
122
123 spin_lock(&object->lock);
124 cookie = object->cookie;
125 if (cookie) {
126 /* delete the page from the tree if it is now no longer
127 * pending */
128 spin_lock(&cookie->stores_lock);
129 radix_tree_tag_clear(&cookie->stores, page->index,
130 FSCACHE_COOKIE_STORING_TAG);
131 if (!radix_tree_tag_get(&cookie->stores, page->index,
132 FSCACHE_COOKIE_PENDING_TAG)) {
133 fscache_stat(&fscache_n_store_radix_deletes);
134 xpage = radix_tree_delete(&cookie->stores, page->index);
135 }
136 spin_unlock(&cookie->stores_lock);
137 wake_up_bit(&cookie->flags, 0);
138 }
139 spin_unlock(&object->lock);
140 if (xpage)
141 page_cache_release(xpage);
142 }
143
144 /*
145 * actually apply the changed attributes to a cache object
146 */
147 static void fscache_attr_changed_op(struct fscache_operation *op)
148 {
149 struct fscache_object *object = op->object;
150 int ret;
151
152 _enter("{OBJ%x OP%x}", object->debug_id, op->debug_id);
153
154 fscache_stat(&fscache_n_attr_changed_calls);
155
156 if (fscache_object_is_active(object)) {
157 fscache_set_op_state(op, "CallFS");
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 fscache_set_op_state(op, "Done");
162 if (ret < 0)
163 fscache_abort_object(object);
164 }
165
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, NULL);
191 fscache_operation_init_slow(op, fscache_attr_changed_op);
192 op->flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_EXCLUSIVE);
193 fscache_set_op_name(op, "Attr");
194
195 spin_lock(&cookie->lock);
196
197 if (hlist_empty(&cookie->backing_objects))
198 goto nobufs;
199 object = hlist_entry(cookie->backing_objects.first,
200 struct fscache_object, cookie_link);
201
202 if (fscache_submit_exclusive_op(object, op) < 0)
203 goto nobufs;
204 spin_unlock(&cookie->lock);
205 fscache_stat(&fscache_n_attr_changed_ok);
206 fscache_put_operation(op);
207 _leave(" = 0");
208 return 0;
209
210 nobufs:
211 spin_unlock(&cookie->lock);
212 kfree(op);
213 fscache_stat(&fscache_n_attr_changed_nobufs);
214 _leave(" = %d", -ENOBUFS);
215 return -ENOBUFS;
216 }
217 EXPORT_SYMBOL(__fscache_attr_changed);
218
219 /*
220 * handle secondary execution given to a retrieval op on behalf of the
221 * cache
222 */
223 static void fscache_retrieval_work(struct work_struct *work)
224 {
225 struct fscache_retrieval *op =
226 container_of(work, struct fscache_retrieval, op.fast_work);
227 unsigned long start;
228
229 _enter("{OP%x}", op->op.debug_id);
230
231 start = jiffies;
232 op->op.processor(&op->op);
233 fscache_hist(fscache_ops_histogram, start);
234 fscache_put_operation(&op->op);
235 }
236
237 /*
238 * release a retrieval op reference
239 */
240 static void fscache_release_retrieval_op(struct fscache_operation *_op)
241 {
242 struct fscache_retrieval *op =
243 container_of(_op, struct fscache_retrieval, op);
244
245 _enter("{OP%x}", op->op.debug_id);
246
247 fscache_hist(fscache_retrieval_histogram, op->start_time);
248 if (op->context)
249 fscache_put_context(op->op.object->cookie, op->context);
250
251 _leave("");
252 }
253
254 /*
255 * allocate a retrieval op
256 */
257 static struct fscache_retrieval *fscache_alloc_retrieval(
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, fscache_release_retrieval_op);
272 op->op.flags = FSCACHE_OP_MYTHREAD | (1 << FSCACHE_OP_WAITING);
273 op->mapping = mapping;
274 op->end_io_func = end_io_func;
275 op->context = context;
276 op->start_time = jiffies;
277 INIT_WORK(&op->op.fast_work, fscache_retrieval_work);
278 INIT_LIST_HEAD(&op->to_do);
279 fscache_set_op_name(&op->op, "Retr");
280 return op;
281 }
282
283 /*
284 * wait for a deferred lookup to complete
285 */
286 static 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 * read a page from the cache or allocate a block in which to store it
318 * - we return:
319 * -ENOMEM - out of memory, nothing done
320 * -ERESTARTSYS - interrupted
321 * -ENOBUFS - no backing object available in which to cache the block
322 * -ENODATA - no data available in the backing object for this block
323 * 0 - dispatched a read - it'll call end_io_func() when finished
324 */
325 int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
326 struct page *page,
327 fscache_rw_complete_t end_io_func,
328 void *context,
329 gfp_t gfp)
330 {
331 struct fscache_retrieval *op;
332 struct fscache_object *object;
333 int ret;
334
335 _enter("%p,%p,,,", cookie, page);
336
337 fscache_stat(&fscache_n_retrievals);
338
339 if (hlist_empty(&cookie->backing_objects))
340 goto nobufs;
341
342 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
343 ASSERTCMP(page, !=, NULL);
344
345 if (fscache_wait_for_deferred_lookup(cookie) < 0)
346 return -ERESTARTSYS;
347
348 op = fscache_alloc_retrieval(page->mapping, end_io_func, context);
349 if (!op) {
350 _leave(" = -ENOMEM");
351 return -ENOMEM;
352 }
353 fscache_set_op_name(&op->op, "RetrRA1");
354
355 spin_lock(&cookie->lock);
356
357 if (hlist_empty(&cookie->backing_objects))
358 goto nobufs_unlock;
359 object = hlist_entry(cookie->backing_objects.first,
360 struct fscache_object, cookie_link);
361
362 ASSERTCMP(object->state, >, FSCACHE_OBJECT_LOOKING_UP);
363
364 atomic_inc(&object->n_reads);
365 set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
366
367 if (fscache_submit_op(object, &op->op) < 0)
368 goto nobufs_unlock;
369 spin_unlock(&cookie->lock);
370
371 fscache_stat(&fscache_n_retrieval_ops);
372
373 /* pin the netfs read context in case we need to do the actual netfs
374 * read because we've encountered a cache read failure */
375 fscache_get_context(object->cookie, op->context);
376
377 /* we wait for the operation to become active, and then process it
378 * *here*, in this thread, and not in the thread pool */
379 if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) {
380 _debug(">>> WT");
381 fscache_stat(&fscache_n_retrieval_op_waits);
382 if (wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
383 fscache_wait_bit_interruptible,
384 TASK_INTERRUPTIBLE) < 0) {
385 ret = fscache_cancel_op(&op->op);
386 if (ret == 0) {
387 ret = -ERESTARTSYS;
388 goto error;
389 }
390
391 /* it's been removed from the pending queue by another
392 * party, so we should get to run shortly */
393 wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
394 fscache_wait_bit, TASK_UNINTERRUPTIBLE);
395 }
396 _debug("<<< GO");
397 }
398
399 /* ask the cache to honour the operation */
400 if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) {
401 fscache_stat(&fscache_n_cop_allocate_page);
402 ret = object->cache->ops->allocate_page(op, page, gfp);
403 fscache_stat_d(&fscache_n_cop_allocate_page);
404 if (ret == 0)
405 ret = -ENODATA;
406 } else {
407 fscache_stat(&fscache_n_cop_read_or_alloc_page);
408 ret = object->cache->ops->read_or_alloc_page(op, page, gfp);
409 fscache_stat_d(&fscache_n_cop_read_or_alloc_page);
410 }
411
412 error:
413 if (ret == -ENOMEM)
414 fscache_stat(&fscache_n_retrievals_nomem);
415 else if (ret == -ERESTARTSYS)
416 fscache_stat(&fscache_n_retrievals_intr);
417 else if (ret == -ENODATA)
418 fscache_stat(&fscache_n_retrievals_nodata);
419 else if (ret < 0)
420 fscache_stat(&fscache_n_retrievals_nobufs);
421 else
422 fscache_stat(&fscache_n_retrievals_ok);
423
424 fscache_put_retrieval(op);
425 _leave(" = %d", ret);
426 return ret;
427
428 nobufs_unlock:
429 spin_unlock(&cookie->lock);
430 kfree(op);
431 nobufs:
432 fscache_stat(&fscache_n_retrievals_nobufs);
433 _leave(" = -ENOBUFS");
434 return -ENOBUFS;
435 }
436 EXPORT_SYMBOL(__fscache_read_or_alloc_page);
437
438 /*
439 * read a list of page from the cache or allocate a block in which to store
440 * them
441 * - we return:
442 * -ENOMEM - out of memory, some pages may be being read
443 * -ERESTARTSYS - interrupted, some pages may be being read
444 * -ENOBUFS - no backing object or space available in which to cache any
445 * pages not being read
446 * -ENODATA - no data available in the backing object for some or all of
447 * the pages
448 * 0 - dispatched a read on all pages
449 *
450 * end_io_func() will be called for each page read from the cache as it is
451 * finishes being read
452 *
453 * any pages for which a read is dispatched will be removed from pages and
454 * nr_pages
455 */
456 int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
457 struct address_space *mapping,
458 struct list_head *pages,
459 unsigned *nr_pages,
460 fscache_rw_complete_t end_io_func,
461 void *context,
462 gfp_t gfp)
463 {
464 struct fscache_retrieval *op;
465 struct fscache_object *object;
466 int ret;
467
468 _enter("%p,,%d,,,", cookie, *nr_pages);
469
470 fscache_stat(&fscache_n_retrievals);
471
472 if (hlist_empty(&cookie->backing_objects))
473 goto nobufs;
474
475 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
476 ASSERTCMP(*nr_pages, >, 0);
477 ASSERT(!list_empty(pages));
478
479 if (fscache_wait_for_deferred_lookup(cookie) < 0)
480 return -ERESTARTSYS;
481
482 op = fscache_alloc_retrieval(mapping, end_io_func, context);
483 if (!op)
484 return -ENOMEM;
485 fscache_set_op_name(&op->op, "RetrRAN");
486
487 spin_lock(&cookie->lock);
488
489 if (hlist_empty(&cookie->backing_objects))
490 goto nobufs_unlock;
491 object = hlist_entry(cookie->backing_objects.first,
492 struct fscache_object, cookie_link);
493
494 atomic_inc(&object->n_reads);
495 set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
496
497 if (fscache_submit_op(object, &op->op) < 0)
498 goto nobufs_unlock;
499 spin_unlock(&cookie->lock);
500
501 fscache_stat(&fscache_n_retrieval_ops);
502
503 /* pin the netfs read context in case we need to do the actual netfs
504 * read because we've encountered a cache read failure */
505 fscache_get_context(object->cookie, op->context);
506
507 /* we wait for the operation to become active, and then process it
508 * *here*, in this thread, and not in the thread pool */
509 if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) {
510 _debug(">>> WT");
511 fscache_stat(&fscache_n_retrieval_op_waits);
512 if (wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
513 fscache_wait_bit_interruptible,
514 TASK_INTERRUPTIBLE) < 0) {
515 ret = fscache_cancel_op(&op->op);
516 if (ret == 0) {
517 ret = -ERESTARTSYS;
518 goto error;
519 }
520
521 /* it's been removed from the pending queue by another
522 * party, so we should get to run shortly */
523 wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
524 fscache_wait_bit, TASK_UNINTERRUPTIBLE);
525 }
526 _debug("<<< GO");
527 }
528
529 /* ask the cache to honour the operation */
530 if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) {
531 fscache_stat(&fscache_n_cop_allocate_pages);
532 ret = object->cache->ops->allocate_pages(
533 op, pages, nr_pages, gfp);
534 fscache_stat_d(&fscache_n_cop_allocate_pages);
535 } else {
536 fscache_stat(&fscache_n_cop_read_or_alloc_pages);
537 ret = object->cache->ops->read_or_alloc_pages(
538 op, pages, nr_pages, gfp);
539 fscache_stat_d(&fscache_n_cop_read_or_alloc_pages);
540 }
541
542 error:
543 if (ret == -ENOMEM)
544 fscache_stat(&fscache_n_retrievals_nomem);
545 else if (ret == -ERESTARTSYS)
546 fscache_stat(&fscache_n_retrievals_intr);
547 else if (ret == -ENODATA)
548 fscache_stat(&fscache_n_retrievals_nodata);
549 else if (ret < 0)
550 fscache_stat(&fscache_n_retrievals_nobufs);
551 else
552 fscache_stat(&fscache_n_retrievals_ok);
553
554 fscache_put_retrieval(op);
555 _leave(" = %d", ret);
556 return ret;
557
558 nobufs_unlock:
559 spin_unlock(&cookie->lock);
560 kfree(op);
561 nobufs:
562 fscache_stat(&fscache_n_retrievals_nobufs);
563 _leave(" = -ENOBUFS");
564 return -ENOBUFS;
565 }
566 EXPORT_SYMBOL(__fscache_read_or_alloc_pages);
567
568 /*
569 * allocate a block in the cache on which to store a page
570 * - we return:
571 * -ENOMEM - out of memory, nothing done
572 * -ERESTARTSYS - interrupted
573 * -ENOBUFS - no backing object available in which to cache the block
574 * 0 - block allocated
575 */
576 int __fscache_alloc_page(struct fscache_cookie *cookie,
577 struct page *page,
578 gfp_t gfp)
579 {
580 struct fscache_retrieval *op;
581 struct fscache_object *object;
582 int ret;
583
584 _enter("%p,%p,,,", cookie, page);
585
586 fscache_stat(&fscache_n_allocs);
587
588 if (hlist_empty(&cookie->backing_objects))
589 goto nobufs;
590
591 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
592 ASSERTCMP(page, !=, NULL);
593
594 if (fscache_wait_for_deferred_lookup(cookie) < 0)
595 return -ERESTARTSYS;
596
597 op = fscache_alloc_retrieval(page->mapping, NULL, NULL);
598 if (!op)
599 return -ENOMEM;
600 fscache_set_op_name(&op->op, "RetrAL1");
601
602 spin_lock(&cookie->lock);
603
604 if (hlist_empty(&cookie->backing_objects))
605 goto nobufs_unlock;
606 object = hlist_entry(cookie->backing_objects.first,
607 struct fscache_object, cookie_link);
608
609 if (fscache_submit_op(object, &op->op) < 0)
610 goto nobufs_unlock;
611 spin_unlock(&cookie->lock);
612
613 fscache_stat(&fscache_n_alloc_ops);
614
615 if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) {
616 _debug(">>> WT");
617 fscache_stat(&fscache_n_alloc_op_waits);
618 if (wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
619 fscache_wait_bit_interruptible,
620 TASK_INTERRUPTIBLE) < 0) {
621 ret = fscache_cancel_op(&op->op);
622 if (ret == 0) {
623 ret = -ERESTARTSYS;
624 goto error;
625 }
626
627 /* it's been removed from the pending queue by another
628 * party, so we should get to run shortly */
629 wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
630 fscache_wait_bit, TASK_UNINTERRUPTIBLE);
631 }
632 _debug("<<< GO");
633 }
634
635 /* ask the cache to honour the operation */
636 fscache_stat(&fscache_n_cop_allocate_page);
637 ret = object->cache->ops->allocate_page(op, page, gfp);
638 fscache_stat_d(&fscache_n_cop_allocate_page);
639
640 error:
641 if (ret == -ERESTARTSYS)
642 fscache_stat(&fscache_n_allocs_intr);
643 else if (ret < 0)
644 fscache_stat(&fscache_n_allocs_nobufs);
645 else
646 fscache_stat(&fscache_n_allocs_ok);
647
648 fscache_put_retrieval(op);
649 _leave(" = %d", ret);
650 return ret;
651
652 nobufs_unlock:
653 spin_unlock(&cookie->lock);
654 kfree(op);
655 nobufs:
656 fscache_stat(&fscache_n_allocs_nobufs);
657 _leave(" = -ENOBUFS");
658 return -ENOBUFS;
659 }
660 EXPORT_SYMBOL(__fscache_alloc_page);
661
662 /*
663 * release a write op reference
664 */
665 static void fscache_release_write_op(struct fscache_operation *_op)
666 {
667 _enter("{OP%x}", _op->debug_id);
668 }
669
670 /*
671 * perform the background storage of a page into the cache
672 */
673 static void fscache_write_op(struct fscache_operation *_op)
674 {
675 struct fscache_storage *op =
676 container_of(_op, struct fscache_storage, op);
677 struct fscache_object *object = op->op.object;
678 struct fscache_cookie *cookie;
679 struct page *page;
680 unsigned n;
681 void *results[1];
682 int ret;
683
684 _enter("{OP%x,%d}", op->op.debug_id, atomic_read(&op->op.usage));
685
686 fscache_set_op_state(&op->op, "GetPage");
687
688 spin_lock(&object->lock);
689 cookie = object->cookie;
690
691 if (!fscache_object_is_active(object) || !cookie) {
692 spin_unlock(&object->lock);
693 _leave("");
694 return;
695 }
696
697 spin_lock(&cookie->stores_lock);
698
699 fscache_stat(&fscache_n_store_calls);
700
701 /* find a page to store */
702 page = NULL;
703 n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0, 1,
704 FSCACHE_COOKIE_PENDING_TAG);
705 if (n != 1)
706 goto superseded;
707 page = results[0];
708 _debug("gang %d [%lx]", n, page->index);
709 if (page->index > op->store_limit) {
710 fscache_stat(&fscache_n_store_pages_over_limit);
711 goto superseded;
712 }
713
714 if (page) {
715 radix_tree_tag_set(&cookie->stores, page->index,
716 FSCACHE_COOKIE_STORING_TAG);
717 radix_tree_tag_clear(&cookie->stores, page->index,
718 FSCACHE_COOKIE_PENDING_TAG);
719 }
720
721 spin_unlock(&cookie->stores_lock);
722 spin_unlock(&object->lock);
723
724 if (page) {
725 fscache_set_op_state(&op->op, "Store");
726 fscache_stat(&fscache_n_store_pages);
727 fscache_stat(&fscache_n_cop_write_page);
728 ret = object->cache->ops->write_page(op, page);
729 fscache_stat_d(&fscache_n_cop_write_page);
730 fscache_set_op_state(&op->op, "EndWrite");
731 fscache_end_page_write(object, page);
732 if (ret < 0) {
733 fscache_set_op_state(&op->op, "Abort");
734 fscache_abort_object(object);
735 } else {
736 fscache_enqueue_operation(&op->op);
737 }
738 }
739
740 _leave("");
741 return;
742
743 superseded:
744 /* this writer is going away and there aren't any more things to
745 * write */
746 _debug("cease");
747 spin_unlock(&cookie->stores_lock);
748 clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
749 spin_unlock(&object->lock);
750 _leave("");
751 }
752
753 /*
754 * request a page be stored in the cache
755 * - returns:
756 * -ENOMEM - out of memory, nothing done
757 * -ENOBUFS - no backing object available in which to cache the page
758 * 0 - dispatched a write - it'll call end_io_func() when finished
759 *
760 * if the cookie still has a backing object at this point, that object can be
761 * in one of a few states with respect to storage processing:
762 *
763 * (1) negative lookup, object not yet created (FSCACHE_COOKIE_CREATING is
764 * set)
765 *
766 * (a) no writes yet (set FSCACHE_COOKIE_PENDING_FILL and queue deferred
767 * fill op)
768 *
769 * (b) writes deferred till post-creation (mark page for writing and
770 * return immediately)
771 *
772 * (2) negative lookup, object created, initial fill being made from netfs
773 * (FSCACHE_COOKIE_INITIAL_FILL is set)
774 *
775 * (a) fill point not yet reached this page (mark page for writing and
776 * return)
777 *
778 * (b) fill point passed this page (queue op to store this page)
779 *
780 * (3) object extant (queue op to store this page)
781 *
782 * any other state is invalid
783 */
784 int __fscache_write_page(struct fscache_cookie *cookie,
785 struct page *page,
786 gfp_t gfp)
787 {
788 struct fscache_storage *op;
789 struct fscache_object *object;
790 int ret;
791
792 _enter("%p,%x,", cookie, (u32) page->flags);
793
794 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
795 ASSERT(PageFsCache(page));
796
797 fscache_stat(&fscache_n_stores);
798
799 op = kzalloc(sizeof(*op), GFP_NOIO);
800 if (!op)
801 goto nomem;
802
803 fscache_operation_init(&op->op, fscache_release_write_op);
804 fscache_operation_init_slow(&op->op, fscache_write_op);
805 op->op.flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_WAITING);
806 fscache_set_op_name(&op->op, "Write1");
807
808 ret = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
809 if (ret < 0)
810 goto nomem_free;
811
812 ret = -ENOBUFS;
813 spin_lock(&cookie->lock);
814
815 if (hlist_empty(&cookie->backing_objects))
816 goto nobufs;
817 object = hlist_entry(cookie->backing_objects.first,
818 struct fscache_object, cookie_link);
819 if (test_bit(FSCACHE_IOERROR, &object->cache->flags))
820 goto nobufs;
821
822 /* add the page to the pending-storage radix tree on the backing
823 * object */
824 spin_lock(&object->lock);
825 spin_lock(&cookie->stores_lock);
826
827 _debug("store limit %llx", (unsigned long long) object->store_limit);
828
829 ret = radix_tree_insert(&cookie->stores, page->index, page);
830 if (ret < 0) {
831 if (ret == -EEXIST)
832 goto already_queued;
833 _debug("insert failed %d", ret);
834 goto nobufs_unlock_obj;
835 }
836
837 radix_tree_tag_set(&cookie->stores, page->index,
838 FSCACHE_COOKIE_PENDING_TAG);
839 page_cache_get(page);
840
841 /* we only want one writer at a time, but we do need to queue new
842 * writers after exclusive ops */
843 if (test_and_set_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags))
844 goto already_pending;
845
846 spin_unlock(&cookie->stores_lock);
847 spin_unlock(&object->lock);
848
849 op->op.debug_id = atomic_inc_return(&fscache_op_debug_id);
850 op->store_limit = object->store_limit;
851
852 if (fscache_submit_op(object, &op->op) < 0)
853 goto submit_failed;
854
855 spin_unlock(&cookie->lock);
856 radix_tree_preload_end();
857 fscache_stat(&fscache_n_store_ops);
858 fscache_stat(&fscache_n_stores_ok);
859
860 /* the slow work queue now carries its own ref on the object */
861 fscache_put_operation(&op->op);
862 _leave(" = 0");
863 return 0;
864
865 already_queued:
866 fscache_stat(&fscache_n_stores_again);
867 already_pending:
868 spin_unlock(&cookie->stores_lock);
869 spin_unlock(&object->lock);
870 spin_unlock(&cookie->lock);
871 radix_tree_preload_end();
872 kfree(op);
873 fscache_stat(&fscache_n_stores_ok);
874 _leave(" = 0");
875 return 0;
876
877 submit_failed:
878 spin_lock(&cookie->stores_lock);
879 radix_tree_delete(&cookie->stores, page->index);
880 spin_unlock(&cookie->stores_lock);
881 page_cache_release(page);
882 ret = -ENOBUFS;
883 goto nobufs;
884
885 nobufs_unlock_obj:
886 spin_unlock(&object->lock);
887 nobufs:
888 spin_unlock(&cookie->lock);
889 radix_tree_preload_end();
890 kfree(op);
891 fscache_stat(&fscache_n_stores_nobufs);
892 _leave(" = -ENOBUFS");
893 return -ENOBUFS;
894
895 nomem_free:
896 kfree(op);
897 nomem:
898 fscache_stat(&fscache_n_stores_oom);
899 _leave(" = -ENOMEM");
900 return -ENOMEM;
901 }
902 EXPORT_SYMBOL(__fscache_write_page);
903
904 /*
905 * remove a page from the cache
906 */
907 void __fscache_uncache_page(struct fscache_cookie *cookie, struct page *page)
908 {
909 struct fscache_object *object;
910
911 _enter(",%p", page);
912
913 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
914 ASSERTCMP(page, !=, NULL);
915
916 fscache_stat(&fscache_n_uncaches);
917
918 /* cache withdrawal may beat us to it */
919 if (!PageFsCache(page))
920 goto done;
921
922 /* get the object */
923 spin_lock(&cookie->lock);
924
925 if (hlist_empty(&cookie->backing_objects)) {
926 ClearPageFsCache(page);
927 goto done_unlock;
928 }
929
930 object = hlist_entry(cookie->backing_objects.first,
931 struct fscache_object, cookie_link);
932
933 /* there might now be stuff on disk we could read */
934 clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
935
936 /* only invoke the cache backend if we managed to mark the page
937 * uncached here; this deals with synchronisation vs withdrawal */
938 if (TestClearPageFsCache(page) &&
939 object->cache->ops->uncache_page) {
940 /* the cache backend releases the cookie lock */
941 fscache_stat(&fscache_n_cop_uncache_page);
942 object->cache->ops->uncache_page(object, page);
943 fscache_stat_d(&fscache_n_cop_uncache_page);
944 goto done;
945 }
946
947 done_unlock:
948 spin_unlock(&cookie->lock);
949 done:
950 _leave("");
951 }
952 EXPORT_SYMBOL(__fscache_uncache_page);
953
954 /**
955 * fscache_mark_pages_cached - Mark pages as being cached
956 * @op: The retrieval op pages are being marked for
957 * @pagevec: The pages to be marked
958 *
959 * Mark a bunch of netfs pages as being cached. After this is called,
960 * the netfs must call fscache_uncache_page() to remove the mark.
961 */
962 void fscache_mark_pages_cached(struct fscache_retrieval *op,
963 struct pagevec *pagevec)
964 {
965 struct fscache_cookie *cookie = op->op.object->cookie;
966 unsigned long loop;
967
968 #ifdef CONFIG_FSCACHE_STATS
969 atomic_add(pagevec->nr, &fscache_n_marks);
970 #endif
971
972 for (loop = 0; loop < pagevec->nr; loop++) {
973 struct page *page = pagevec->pages[loop];
974
975 _debug("- mark %p{%lx}", page, page->index);
976 if (TestSetPageFsCache(page)) {
977 static bool once_only;
978 if (!once_only) {
979 once_only = true;
980 printk(KERN_WARNING "FS-Cache:"
981 " Cookie type %s marked page %lx"
982 " multiple times\n",
983 cookie->def->name, page->index);
984 }
985 }
986 }
987
988 if (cookie->def->mark_pages_cached)
989 cookie->def->mark_pages_cached(cookie->netfs_data,
990 op->mapping, pagevec);
991 pagevec_reinit(pagevec);
992 }
993 EXPORT_SYMBOL(fscache_mark_pages_cached);
x86 "subsystem" repository