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 */
__fscache_check_page_write(struct fscache_cookie * cookie,struct page * page)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 */
__fscache_wait_on_page_write(struct fscache_cookie * cookie,struct page * page)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 */
__fscache_maybe_release_page(struct fscache_cookie * cookie,struct page * page,gfp_t gfp)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 */
fscache_end_page_write(struct fscache_object * object,struct page * page)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 */
fscache_attr_changed_op(struct fscache_operation * op)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 _leave("");
166 }
167
168 /*
169 * notification that the attributes on an object have changed
170 */
__fscache_attr_changed(struct fscache_cookie * cookie)171 int __fscache_attr_changed(struct fscache_cookie *cookie)
172 {
173 struct fscache_operation *op;
174 struct fscache_object *object;
175
176 _enter("%p", cookie);
177
178 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
179
180 fscache_stat(&fscache_n_attr_changed);
181
182 op = kzalloc(sizeof(*op), GFP_KERNEL);
183 if (!op) {
184 fscache_stat(&fscache_n_attr_changed_nomem);
185 _leave(" = -ENOMEM");
186 return -ENOMEM;
187 }
188
189 fscache_operation_init(op, fscache_attr_changed_op, NULL);
190 op->flags = FSCACHE_OP_ASYNC | (1 << FSCACHE_OP_EXCLUSIVE);
191
192 spin_lock(&cookie->lock);
193
194 if (hlist_empty(&cookie->backing_objects))
195 goto nobufs;
196 object = hlist_entry(cookie->backing_objects.first,
197 struct fscache_object, cookie_link);
198
199 if (fscache_submit_exclusive_op(object, op) < 0)
200 goto nobufs;
201 spin_unlock(&cookie->lock);
202 fscache_stat(&fscache_n_attr_changed_ok);
203 fscache_put_operation(op);
204 _leave(" = 0");
205 return 0;
206
207 nobufs:
208 spin_unlock(&cookie->lock);
209 kfree(op);
210 fscache_stat(&fscache_n_attr_changed_nobufs);
211 _leave(" = %d", -ENOBUFS);
212 return -ENOBUFS;
213 }
214 EXPORT_SYMBOL(__fscache_attr_changed);
215
216 /*
217 * release a retrieval op reference
218 */
fscache_release_retrieval_op(struct fscache_operation * _op)219 static void fscache_release_retrieval_op(struct fscache_operation *_op)
220 {
221 struct fscache_retrieval *op =
222 container_of(_op, struct fscache_retrieval, op);
223
224 _enter("{OP%x}", op->op.debug_id);
225
226 fscache_hist(fscache_retrieval_histogram, op->start_time);
227 if (op->context)
228 fscache_put_context(op->op.object->cookie, op->context);
229
230 _leave("");
231 }
232
233 /*
234 * allocate a retrieval op
235 */
fscache_alloc_retrieval(struct address_space * mapping,fscache_rw_complete_t end_io_func,void * context)236 static struct fscache_retrieval *fscache_alloc_retrieval(
237 struct address_space *mapping,
238 fscache_rw_complete_t end_io_func,
239 void *context)
240 {
241 struct fscache_retrieval *op;
242
243 /* allocate a retrieval operation and attempt to submit it */
244 op = kzalloc(sizeof(*op), GFP_NOIO);
245 if (!op) {
246 fscache_stat(&fscache_n_retrievals_nomem);
247 return NULL;
248 }
249
250 fscache_operation_init(&op->op, NULL, fscache_release_retrieval_op);
251 op->op.flags = FSCACHE_OP_MYTHREAD | (1 << FSCACHE_OP_WAITING);
252 op->mapping = mapping;
253 op->end_io_func = end_io_func;
254 op->context = context;
255 op->start_time = jiffies;
256 INIT_LIST_HEAD(&op->to_do);
257 return op;
258 }
259
260 /*
261 * wait for a deferred lookup to complete
262 */
fscache_wait_for_deferred_lookup(struct fscache_cookie * cookie)263 static int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie)
264 {
265 unsigned long jif;
266
267 _enter("");
268
269 if (!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)) {
270 _leave(" = 0 [imm]");
271 return 0;
272 }
273
274 fscache_stat(&fscache_n_retrievals_wait);
275
276 jif = jiffies;
277 if (wait_on_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP,
278 fscache_wait_bit_interruptible,
279 TASK_INTERRUPTIBLE) != 0) {
280 fscache_stat(&fscache_n_retrievals_intr);
281 _leave(" = -ERESTARTSYS");
282 return -ERESTARTSYS;
283 }
284
285 ASSERT(!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags));
286
287 smp_rmb();
288 fscache_hist(fscache_retrieval_delay_histogram, jif);
289 _leave(" = 0 [dly]");
290 return 0;
291 }
292
293 /*
294 * wait for an object to become active (or dead)
295 */
fscache_wait_for_retrieval_activation(struct fscache_object * object,struct fscache_retrieval * op,atomic_t * stat_op_waits,atomic_t * stat_object_dead)296 static int fscache_wait_for_retrieval_activation(struct fscache_object *object,
297 struct fscache_retrieval *op,
298 atomic_t *stat_op_waits,
299 atomic_t *stat_object_dead)
300 {
301 int ret;
302
303 if (!test_bit(FSCACHE_OP_WAITING, &op->op.flags))
304 goto check_if_dead;
305
306 _debug(">>> WT");
307 fscache_stat(stat_op_waits);
308 if (wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
309 fscache_wait_bit_interruptible,
310 TASK_INTERRUPTIBLE) < 0) {
311 ret = fscache_cancel_op(&op->op);
312 if (ret == 0)
313 return -ERESTARTSYS;
314
315 /* it's been removed from the pending queue by another party,
316 * so we should get to run shortly */
317 wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
318 fscache_wait_bit, TASK_UNINTERRUPTIBLE);
319 }
320 _debug("<<< GO");
321
322 check_if_dead:
323 if (unlikely(fscache_object_is_dead(object))) {
324 fscache_stat(stat_object_dead);
325 return -ENOBUFS;
326 }
327 return 0;
328 }
329
330 /*
331 * read a page from the cache or allocate a block in which to store it
332 * - we return:
333 * -ENOMEM - out of memory, nothing done
334 * -ERESTARTSYS - interrupted
335 * -ENOBUFS - no backing object available in which to cache the block
336 * -ENODATA - no data available in the backing object for this block
337 * 0 - dispatched a read - it'll call end_io_func() when finished
338 */
__fscache_read_or_alloc_page(struct fscache_cookie * cookie,struct page * page,fscache_rw_complete_t end_io_func,void * context,gfp_t gfp)339 int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
340 struct page *page,
341 fscache_rw_complete_t end_io_func,
342 void *context,
343 gfp_t gfp)
344 {
345 struct fscache_retrieval *op;
346 struct fscache_object *object;
347 int ret;
348
349 _enter("%p,%p,,,", cookie, page);
350
351 fscache_stat(&fscache_n_retrievals);
352
353 if (hlist_empty(&cookie->backing_objects))
354 goto nobufs;
355
356 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
357 ASSERTCMP(page, !=, NULL);
358
359 if (fscache_wait_for_deferred_lookup(cookie) < 0)
360 return -ERESTARTSYS;
361
362 op = fscache_alloc_retrieval(page->mapping, end_io_func, context);
363 if (!op) {
364 _leave(" = -ENOMEM");
365 return -ENOMEM;
366 }
367
368 spin_lock(&cookie->lock);
369
370 if (hlist_empty(&cookie->backing_objects))
371 goto nobufs_unlock;
372 object = hlist_entry(cookie->backing_objects.first,
373 struct fscache_object, cookie_link);
374
375 ASSERTCMP(object->state, >, FSCACHE_OBJECT_LOOKING_UP);
376
377 atomic_inc(&object->n_reads);
378 set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
379
380 if (fscache_submit_op(object, &op->op) < 0)
381 goto nobufs_unlock;
382 spin_unlock(&cookie->lock);
383
384 fscache_stat(&fscache_n_retrieval_ops);
385
386 /* pin the netfs read context in case we need to do the actual netfs
387 * read because we've encountered a cache read failure */
388 fscache_get_context(object->cookie, op->context);
389
390 /* we wait for the operation to become active, and then process it
391 * *here*, in this thread, and not in the thread pool */
392 ret = fscache_wait_for_retrieval_activation(
393 object, op,
394 __fscache_stat(&fscache_n_retrieval_op_waits),
395 __fscache_stat(&fscache_n_retrievals_object_dead));
396 if (ret < 0)
397 goto error;
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 */
__fscache_read_or_alloc_pages(struct fscache_cookie * cookie,struct address_space * mapping,struct list_head * pages,unsigned * nr_pages,fscache_rw_complete_t end_io_func,void * context,gfp_t gfp)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
486 spin_lock(&cookie->lock);
487
488 if (hlist_empty(&cookie->backing_objects))
489 goto nobufs_unlock;
490 object = hlist_entry(cookie->backing_objects.first,
491 struct fscache_object, cookie_link);
492
493 atomic_inc(&object->n_reads);
494 set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
495
496 if (fscache_submit_op(object, &op->op) < 0)
497 goto nobufs_unlock;
498 spin_unlock(&cookie->lock);
499
500 fscache_stat(&fscache_n_retrieval_ops);
501
502 /* pin the netfs read context in case we need to do the actual netfs
503 * read because we've encountered a cache read failure */
504 fscache_get_context(object->cookie, op->context);
505
506 /* we wait for the operation to become active, and then process it
507 * *here*, in this thread, and not in the thread pool */
508 ret = fscache_wait_for_retrieval_activation(
509 object, op,
510 __fscache_stat(&fscache_n_retrieval_op_waits),
511 __fscache_stat(&fscache_n_retrievals_object_dead));
512 if (ret < 0)
513 goto error;
514
515 /* ask the cache to honour the operation */
516 if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) {
517 fscache_stat(&fscache_n_cop_allocate_pages);
518 ret = object->cache->ops->allocate_pages(
519 op, pages, nr_pages, gfp);
520 fscache_stat_d(&fscache_n_cop_allocate_pages);
521 } else {
522 fscache_stat(&fscache_n_cop_read_or_alloc_pages);
523 ret = object->cache->ops->read_or_alloc_pages(
524 op, pages, nr_pages, gfp);
525 fscache_stat_d(&fscache_n_cop_read_or_alloc_pages);
526 }
527
528 error:
529 if (ret == -ENOMEM)
530 fscache_stat(&fscache_n_retrievals_nomem);
531 else if (ret == -ERESTARTSYS)
532 fscache_stat(&fscache_n_retrievals_intr);
533 else if (ret == -ENODATA)
534 fscache_stat(&fscache_n_retrievals_nodata);
535 else if (ret < 0)
536 fscache_stat(&fscache_n_retrievals_nobufs);
537 else
538 fscache_stat(&fscache_n_retrievals_ok);
539
540 fscache_put_retrieval(op);
541 _leave(" = %d", ret);
542 return ret;
543
544 nobufs_unlock:
545 spin_unlock(&cookie->lock);
546 kfree(op);
547 nobufs:
548 fscache_stat(&fscache_n_retrievals_nobufs);
549 _leave(" = -ENOBUFS");
550 return -ENOBUFS;
551 }
552 EXPORT_SYMBOL(__fscache_read_or_alloc_pages);
553
554 /*
555 * allocate a block in the cache on which to store a page
556 * - we return:
557 * -ENOMEM - out of memory, nothing done
558 * -ERESTARTSYS - interrupted
559 * -ENOBUFS - no backing object available in which to cache the block
560 * 0 - block allocated
561 */
__fscache_alloc_page(struct fscache_cookie * cookie,struct page * page,gfp_t gfp)562 int __fscache_alloc_page(struct fscache_cookie *cookie,
563 struct page *page,
564 gfp_t gfp)
565 {
566 struct fscache_retrieval *op;
567 struct fscache_object *object;
568 int ret;
569
570 _enter("%p,%p,,,", cookie, page);
571
572 fscache_stat(&fscache_n_allocs);
573
574 if (hlist_empty(&cookie->backing_objects))
575 goto nobufs;
576
577 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
578 ASSERTCMP(page, !=, NULL);
579
580 if (fscache_wait_for_deferred_lookup(cookie) < 0)
581 return -ERESTARTSYS;
582
583 op = fscache_alloc_retrieval(page->mapping, NULL, NULL);
584 if (!op)
585 return -ENOMEM;
586
587 spin_lock(&cookie->lock);
588
589 if (hlist_empty(&cookie->backing_objects))
590 goto nobufs_unlock;
591 object = hlist_entry(cookie->backing_objects.first,
592 struct fscache_object, cookie_link);
593
594 if (fscache_submit_op(object, &op->op) < 0)
595 goto nobufs_unlock;
596 spin_unlock(&cookie->lock);
597
598 fscache_stat(&fscache_n_alloc_ops);
599
600 ret = fscache_wait_for_retrieval_activation(
601 object, op,
602 __fscache_stat(&fscache_n_alloc_op_waits),
603 __fscache_stat(&fscache_n_allocs_object_dead));
604 if (ret < 0)
605 goto error;
606
607 /* ask the cache to honour the operation */
608 fscache_stat(&fscache_n_cop_allocate_page);
609 ret = object->cache->ops->allocate_page(op, page, gfp);
610 fscache_stat_d(&fscache_n_cop_allocate_page);
611
612 error:
613 if (ret == -ERESTARTSYS)
614 fscache_stat(&fscache_n_allocs_intr);
615 else if (ret < 0)
616 fscache_stat(&fscache_n_allocs_nobufs);
617 else
618 fscache_stat(&fscache_n_allocs_ok);
619
620 fscache_put_retrieval(op);
621 _leave(" = %d", ret);
622 return ret;
623
624 nobufs_unlock:
625 spin_unlock(&cookie->lock);
626 kfree(op);
627 nobufs:
628 fscache_stat(&fscache_n_allocs_nobufs);
629 _leave(" = -ENOBUFS");
630 return -ENOBUFS;
631 }
632 EXPORT_SYMBOL(__fscache_alloc_page);
633
634 /*
635 * release a write op reference
636 */
fscache_release_write_op(struct fscache_operation * _op)637 static void fscache_release_write_op(struct fscache_operation *_op)
638 {
639 _enter("{OP%x}", _op->debug_id);
640 }
641
642 /*
643 * perform the background storage of a page into the cache
644 */
fscache_write_op(struct fscache_operation * _op)645 static void fscache_write_op(struct fscache_operation *_op)
646 {
647 struct fscache_storage *op =
648 container_of(_op, struct fscache_storage, op);
649 struct fscache_object *object = op->op.object;
650 struct fscache_cookie *cookie;
651 struct page *page;
652 unsigned n;
653 void *results[1];
654 int ret;
655
656 _enter("{OP%x,%d}", op->op.debug_id, atomic_read(&op->op.usage));
657
658 spin_lock(&object->lock);
659 cookie = object->cookie;
660
661 if (!fscache_object_is_active(object) || !cookie) {
662 spin_unlock(&object->lock);
663 _leave("");
664 return;
665 }
666
667 spin_lock(&cookie->stores_lock);
668
669 fscache_stat(&fscache_n_store_calls);
670
671 /* find a page to store */
672 page = NULL;
673 n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0, 1,
674 FSCACHE_COOKIE_PENDING_TAG);
675 if (n != 1)
676 goto superseded;
677 page = results[0];
678 _debug("gang %d [%lx]", n, page->index);
679 if (page->index > op->store_limit) {
680 fscache_stat(&fscache_n_store_pages_over_limit);
681 goto superseded;
682 }
683
684 radix_tree_tag_set(&cookie->stores, page->index,
685 FSCACHE_COOKIE_STORING_TAG);
686 radix_tree_tag_clear(&cookie->stores, page->index,
687 FSCACHE_COOKIE_PENDING_TAG);
688
689 spin_unlock(&cookie->stores_lock);
690 spin_unlock(&object->lock);
691
692 fscache_stat(&fscache_n_store_pages);
693 fscache_stat(&fscache_n_cop_write_page);
694 ret = object->cache->ops->write_page(op, page);
695 fscache_stat_d(&fscache_n_cop_write_page);
696 fscache_end_page_write(object, page);
697 if (ret < 0) {
698 fscache_abort_object(object);
699 } else {
700 fscache_enqueue_operation(&op->op);
701 }
702
703 _leave("");
704 return;
705
706 superseded:
707 /* this writer is going away and there aren't any more things to
708 * write */
709 _debug("cease");
710 spin_unlock(&cookie->stores_lock);
711 clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
712 spin_unlock(&object->lock);
713 _leave("");
714 }
715
716 /*
717 * request a page be stored in the cache
718 * - returns:
719 * -ENOMEM - out of memory, nothing done
720 * -ENOBUFS - no backing object available in which to cache the page
721 * 0 - dispatched a write - it'll call end_io_func() when finished
722 *
723 * if the cookie still has a backing object at this point, that object can be
724 * in one of a few states with respect to storage processing:
725 *
726 * (1) negative lookup, object not yet created (FSCACHE_COOKIE_CREATING is
727 * set)
728 *
729 * (a) no writes yet (set FSCACHE_COOKIE_PENDING_FILL and queue deferred
730 * fill op)
731 *
732 * (b) writes deferred till post-creation (mark page for writing and
733 * return immediately)
734 *
735 * (2) negative lookup, object created, initial fill being made from netfs
736 * (FSCACHE_COOKIE_INITIAL_FILL is set)
737 *
738 * (a) fill point not yet reached this page (mark page for writing and
739 * return)
740 *
741 * (b) fill point passed this page (queue op to store this page)
742 *
743 * (3) object extant (queue op to store this page)
744 *
745 * any other state is invalid
746 */
__fscache_write_page(struct fscache_cookie * cookie,struct page * page,gfp_t gfp)747 int __fscache_write_page(struct fscache_cookie *cookie,
748 struct page *page,
749 gfp_t gfp)
750 {
751 struct fscache_storage *op;
752 struct fscache_object *object;
753 int ret;
754
755 _enter("%p,%x,", cookie, (u32) page->flags);
756
757 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
758 ASSERT(PageFsCache(page));
759
760 fscache_stat(&fscache_n_stores);
761
762 op = kzalloc(sizeof(*op), GFP_NOIO);
763 if (!op)
764 goto nomem;
765
766 fscache_operation_init(&op->op, fscache_write_op,
767 fscache_release_write_op);
768 op->op.flags = FSCACHE_OP_ASYNC | (1 << FSCACHE_OP_WAITING);
769
770 ret = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
771 if (ret < 0)
772 goto nomem_free;
773
774 ret = -ENOBUFS;
775 spin_lock(&cookie->lock);
776
777 if (hlist_empty(&cookie->backing_objects))
778 goto nobufs;
779 object = hlist_entry(cookie->backing_objects.first,
780 struct fscache_object, cookie_link);
781 if (test_bit(FSCACHE_IOERROR, &object->cache->flags))
782 goto nobufs;
783
784 /* add the page to the pending-storage radix tree on the backing
785 * object */
786 spin_lock(&object->lock);
787 spin_lock(&cookie->stores_lock);
788
789 _debug("store limit %llx", (unsigned long long) object->store_limit);
790
791 ret = radix_tree_insert(&cookie->stores, page->index, page);
792 if (ret < 0) {
793 if (ret == -EEXIST)
794 goto already_queued;
795 _debug("insert failed %d", ret);
796 goto nobufs_unlock_obj;
797 }
798
799 radix_tree_tag_set(&cookie->stores, page->index,
800 FSCACHE_COOKIE_PENDING_TAG);
801 page_cache_get(page);
802
803 /* we only want one writer at a time, but we do need to queue new
804 * writers after exclusive ops */
805 if (test_and_set_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags))
806 goto already_pending;
807
808 spin_unlock(&cookie->stores_lock);
809 spin_unlock(&object->lock);
810
811 op->op.debug_id = atomic_inc_return(&fscache_op_debug_id);
812 op->store_limit = object->store_limit;
813
814 if (fscache_submit_op(object, &op->op) < 0)
815 goto submit_failed;
816
817 spin_unlock(&cookie->lock);
818 radix_tree_preload_end();
819 fscache_stat(&fscache_n_store_ops);
820 fscache_stat(&fscache_n_stores_ok);
821
822 /* the work queue now carries its own ref on the object */
823 fscache_put_operation(&op->op);
824 _leave(" = 0");
825 return 0;
826
827 already_queued:
828 fscache_stat(&fscache_n_stores_again);
829 already_pending:
830 spin_unlock(&cookie->stores_lock);
831 spin_unlock(&object->lock);
832 spin_unlock(&cookie->lock);
833 radix_tree_preload_end();
834 kfree(op);
835 fscache_stat(&fscache_n_stores_ok);
836 _leave(" = 0");
837 return 0;
838
839 submit_failed:
840 spin_lock(&cookie->stores_lock);
841 radix_tree_delete(&cookie->stores, page->index);
842 spin_unlock(&cookie->stores_lock);
843 page_cache_release(page);
844 ret = -ENOBUFS;
845 goto nobufs;
846
847 nobufs_unlock_obj:
848 spin_unlock(&cookie->stores_lock);
849 spin_unlock(&object->lock);
850 nobufs:
851 spin_unlock(&cookie->lock);
852 radix_tree_preload_end();
853 kfree(op);
854 fscache_stat(&fscache_n_stores_nobufs);
855 _leave(" = -ENOBUFS");
856 return -ENOBUFS;
857
858 nomem_free:
859 kfree(op);
860 nomem:
861 fscache_stat(&fscache_n_stores_oom);
862 _leave(" = -ENOMEM");
863 return -ENOMEM;
864 }
865 EXPORT_SYMBOL(__fscache_write_page);
866
867 /*
868 * remove a page from the cache
869 */
__fscache_uncache_page(struct fscache_cookie * cookie,struct page * page)870 void __fscache_uncache_page(struct fscache_cookie *cookie, struct page *page)
871 {
872 struct fscache_object *object;
873
874 _enter(",%p", page);
875
876 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
877 ASSERTCMP(page, !=, NULL);
878
879 fscache_stat(&fscache_n_uncaches);
880
881 /* cache withdrawal may beat us to it */
882 if (!PageFsCache(page))
883 goto done;
884
885 /* get the object */
886 spin_lock(&cookie->lock);
887
888 if (hlist_empty(&cookie->backing_objects)) {
889 ClearPageFsCache(page);
890 goto done_unlock;
891 }
892
893 object = hlist_entry(cookie->backing_objects.first,
894 struct fscache_object, cookie_link);
895
896 /* there might now be stuff on disk we could read */
897 clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
898
899 /* only invoke the cache backend if we managed to mark the page
900 * uncached here; this deals with synchronisation vs withdrawal */
901 if (TestClearPageFsCache(page) &&
902 object->cache->ops->uncache_page) {
903 /* the cache backend releases the cookie lock */
904 fscache_stat(&fscache_n_cop_uncache_page);
905 object->cache->ops->uncache_page(object, page);
906 fscache_stat_d(&fscache_n_cop_uncache_page);
907 goto done;
908 }
909
910 done_unlock:
911 spin_unlock(&cookie->lock);
912 done:
913 _leave("");
914 }
915 EXPORT_SYMBOL(__fscache_uncache_page);
916
917 /**
918 * fscache_mark_pages_cached - Mark pages as being cached
919 * @op: The retrieval op pages are being marked for
920 * @pagevec: The pages to be marked
921 *
922 * Mark a bunch of netfs pages as being cached. After this is called,
923 * the netfs must call fscache_uncache_page() to remove the mark.
924 */
fscache_mark_pages_cached(struct fscache_retrieval * op,struct pagevec * pagevec)925 void fscache_mark_pages_cached(struct fscache_retrieval *op,
926 struct pagevec *pagevec)
927 {
928 struct fscache_cookie *cookie = op->op.object->cookie;
929 unsigned long loop;
930
931 #ifdef CONFIG_FSCACHE_STATS
932 atomic_add(pagevec->nr, &fscache_n_marks);
933 #endif
934
935 for (loop = 0; loop < pagevec->nr; loop++) {
936 struct page *page = pagevec->pages[loop];
937
938 _debug("- mark %p{%lx}", page, page->index);
939 if (TestSetPageFsCache(page)) {
940 static bool once_only;
941 if (!once_only) {
942 once_only = true;
943 printk(KERN_WARNING "FS-Cache:"
944 " Cookie type %s marked page %lx"
945 " multiple times\n",
946 cookie->def->name, page->index);
947 }
948 }
949 }
950
951 if (cookie->def->mark_pages_cached)
952 cookie->def->mark_pages_cached(cookie->netfs_data,
953 op->mapping, pagevec);
954 pagevec_reinit(pagevec);
955 }
956 EXPORT_SYMBOL(fscache_mark_pages_cached);
957
958 /*
959 * Uncache all the pages in an inode that are marked PG_fscache, assuming them
960 * to be associated with the given cookie.
961 */
__fscache_uncache_all_inode_pages(struct fscache_cookie * cookie,struct inode * inode)962 void __fscache_uncache_all_inode_pages(struct fscache_cookie *cookie,
963 struct inode *inode)
964 {
965 struct address_space *mapping = inode->i_mapping;
966 struct pagevec pvec;
967 pgoff_t next;
968 int i;
969
970 _enter("%p,%p", cookie, inode);
971
972 if (!mapping || mapping->nrpages == 0) {
973 _leave(" [no pages]");
974 return;
975 }
976
977 pagevec_init(&pvec, 0);
978 next = 0;
979 do {
980 if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE))
981 break;
982 for (i = 0; i < pagevec_count(&pvec); i++) {
983 struct page *page = pvec.pages[i];
984 next = page->index;
985 if (PageFsCache(page)) {
986 __fscache_wait_on_page_write(cookie, page);
987 __fscache_uncache_page(cookie, page);
988 }
989 }
990 pagevec_release(&pvec);
991 cond_resched();
992 } while (++next);
993
994 _leave("");
995 }
996 EXPORT_SYMBOL(__fscache_uncache_all_inode_pages);
997