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 trace_fscache_check_page(cookie, page, val, 0);
31
32 return val != NULL;
33 }
34 EXPORT_SYMBOL(__fscache_check_page_write);
35
36 /*
37 * wait for a page to finish being written to the cache
38 */
39 void __fscache_wait_on_page_write(struct fscache_cookie *cookie, struct page *page)
40 {
41 wait_queue_head_t *wq = bit_waitqueue(&cookie->flags, 0);
42
43 trace_fscache_page(cookie, page, fscache_page_write_wait);
44
45 wait_event(*wq, !__fscache_check_page_write(cookie, page));
46 }
47 EXPORT_SYMBOL(__fscache_wait_on_page_write);
48
49 /*
50 * wait for a page to finish being written to the cache. Put a timeout here
51 * since we might be called recursively via parent fs.
52 */
53 static
54 bool release_page_wait_timeout(struct fscache_cookie *cookie, struct page *page)
55 {
56 wait_queue_head_t *wq = bit_waitqueue(&cookie->flags, 0);
57
58 return wait_event_timeout(*wq, !__fscache_check_page_write(cookie, page),
59 HZ);
60 }
61
62 /*
63 * decide whether a page can be released, possibly by cancelling a store to it
64 * - we're allowed to sleep if __GFP_DIRECT_RECLAIM is flagged
65 */
66 bool __fscache_maybe_release_page(struct fscache_cookie *cookie,
67 struct page *page,
68 gfp_t gfp)
69 {
70 struct page *xpage;
71 void *val;
72
73 _enter("%p,%p,%x", cookie, page, gfp);
74
75 trace_fscache_page(cookie, page, fscache_page_maybe_release);
76
77 try_again:
78 rcu_read_lock();
79 val = radix_tree_lookup(&cookie->stores, page->index);
80 if (!val) {
81 rcu_read_unlock();
82 fscache_stat(&fscache_n_store_vmscan_not_storing);
83 __fscache_uncache_page(cookie, page);
84 return true;
85 }
86
87 /* see if the page is actually undergoing storage - if so we can't get
88 * rid of it till the cache has finished with it */
89 if (radix_tree_tag_get(&cookie->stores, page->index,
90 FSCACHE_COOKIE_STORING_TAG)) {
91 rcu_read_unlock();
92 goto page_busy;
93 }
94
95 /* the page is pending storage, so we attempt to cancel the store and
96 * discard the store request so that the page can be reclaimed */
97 spin_lock(&cookie->stores_lock);
98 rcu_read_unlock();
99
100 if (radix_tree_tag_get(&cookie->stores, page->index,
101 FSCACHE_COOKIE_STORING_TAG)) {
102 /* the page started to undergo storage whilst we were looking,
103 * so now we can only wait or return */
104 spin_unlock(&cookie->stores_lock);
105 goto page_busy;
106 }
107
108 xpage = radix_tree_delete(&cookie->stores, page->index);
109 trace_fscache_page(cookie, page, fscache_page_radix_delete);
110 spin_unlock(&cookie->stores_lock);
111
112 if (xpage) {
113 fscache_stat(&fscache_n_store_vmscan_cancelled);
114 fscache_stat(&fscache_n_store_radix_deletes);
115 ASSERTCMP(xpage, ==, page);
116 } else {
117 fscache_stat(&fscache_n_store_vmscan_gone);
118 }
119
120 wake_up_bit(&cookie->flags, 0);
121 trace_fscache_wake_cookie(cookie);
122 if (xpage)
123 put_page(xpage);
124 __fscache_uncache_page(cookie, page);
125 return true;
126
127 page_busy:
128 /* We will wait here if we're allowed to, but that could deadlock the
129 * allocator as the work threads writing to the cache may all end up
130 * sleeping on memory allocation, so we may need to impose a timeout
131 * too. */
132 if (!(gfp & __GFP_DIRECT_RECLAIM) || !(gfp & __GFP_FS)) {
133 fscache_stat(&fscache_n_store_vmscan_busy);
134 return false;
135 }
136
137 fscache_stat(&fscache_n_store_vmscan_wait);
138 if (!release_page_wait_timeout(cookie, page))
139 _debug("fscache writeout timeout page: %p{%lx}",
140 page, page->index);
141
142 gfp &= ~__GFP_DIRECT_RECLAIM;
143 goto try_again;
144 }
145 EXPORT_SYMBOL(__fscache_maybe_release_page);
146
147 /*
148 * note that a page has finished being written to the cache
149 */
150 static void fscache_end_page_write(struct fscache_object *object,
151 struct page *page)
152 {
153 struct fscache_cookie *cookie;
154 struct page *xpage = NULL, *val;
155
156 spin_lock(&object->lock);
157 cookie = object->cookie;
158 if (cookie) {
159 /* delete the page from the tree if it is now no longer
160 * pending */
161 spin_lock(&cookie->stores_lock);
162 radix_tree_tag_clear(&cookie->stores, page->index,
163 FSCACHE_COOKIE_STORING_TAG);
164 trace_fscache_page(cookie, page, fscache_page_radix_clear_store);
165 if (!radix_tree_tag_get(&cookie->stores, page->index,
166 FSCACHE_COOKIE_PENDING_TAG)) {
167 fscache_stat(&fscache_n_store_radix_deletes);
168 xpage = radix_tree_delete(&cookie->stores, page->index);
169 trace_fscache_page(cookie, page, fscache_page_radix_delete);
170 trace_fscache_page(cookie, page, fscache_page_write_end);
171
172 val = radix_tree_lookup(&cookie->stores, page->index);
173 trace_fscache_check_page(cookie, page, val, 1);
174 } else {
175 trace_fscache_page(cookie, page, fscache_page_write_end_pend);
176 }
177 spin_unlock(&cookie->stores_lock);
178 wake_up_bit(&cookie->flags, 0);
179 trace_fscache_wake_cookie(cookie);
180 } else {
181 trace_fscache_page(cookie, page, fscache_page_write_end_noc);
182 }
183 spin_unlock(&object->lock);
184 if (xpage)
185 put_page(xpage);
186 }
187
188 /*
189 * actually apply the changed attributes to a cache object
190 */
191 static void fscache_attr_changed_op(struct fscache_operation *op)
192 {
193 struct fscache_object *object = op->object;
194 int ret;
195
196 _enter("{OBJ%x OP%x}", object->debug_id, op->debug_id);
197
198 fscache_stat(&fscache_n_attr_changed_calls);
199
200 if (fscache_object_is_active(object)) {
201 fscache_stat(&fscache_n_cop_attr_changed);
202 ret = object->cache->ops->attr_changed(object);
203 fscache_stat_d(&fscache_n_cop_attr_changed);
204 if (ret < 0)
205 fscache_abort_object(object);
206 fscache_op_complete(op, ret < 0);
207 } else {
208 fscache_op_complete(op, true);
209 }
210
211 _leave("");
212 }
213
214 /*
215 * notification that the attributes on an object have changed
216 */
217 int __fscache_attr_changed(struct fscache_cookie *cookie)
218 {
219 struct fscache_operation *op;
220 struct fscache_object *object;
221 bool wake_cookie = false;
222
223 _enter("%p", cookie);
224
225 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
226
227 fscache_stat(&fscache_n_attr_changed);
228
229 op = kzalloc(sizeof(*op), GFP_KERNEL);
230 if (!op) {
231 fscache_stat(&fscache_n_attr_changed_nomem);
232 _leave(" = -ENOMEM");
233 return -ENOMEM;
234 }
235
236 fscache_operation_init(cookie, op, fscache_attr_changed_op, NULL, NULL);
237 trace_fscache_page_op(cookie, NULL, op, fscache_page_op_attr_changed);
238 op->flags = FSCACHE_OP_ASYNC |
239 (1 << FSCACHE_OP_EXCLUSIVE) |
240 (1 << FSCACHE_OP_UNUSE_COOKIE);
241
242 spin_lock(&cookie->lock);
243
244 if (!fscache_cookie_enabled(cookie) ||
245 hlist_empty(&cookie->backing_objects))
246 goto nobufs;
247 object = hlist_entry(cookie->backing_objects.first,
248 struct fscache_object, cookie_link);
249
250 __fscache_use_cookie(cookie);
251 if (fscache_submit_exclusive_op(object, op) < 0)
252 goto nobufs_dec;
253 spin_unlock(&cookie->lock);
254 fscache_stat(&fscache_n_attr_changed_ok);
255 fscache_put_operation(op);
256 _leave(" = 0");
257 return 0;
258
259 nobufs_dec:
260 wake_cookie = __fscache_unuse_cookie(cookie);
261 nobufs:
262 spin_unlock(&cookie->lock);
263 fscache_put_operation(op);
264 if (wake_cookie)
265 __fscache_wake_unused_cookie(cookie);
266 fscache_stat(&fscache_n_attr_changed_nobufs);
267 _leave(" = %d", -ENOBUFS);
268 return -ENOBUFS;
269 }
270 EXPORT_SYMBOL(__fscache_attr_changed);
271
272 /*
273 * Handle cancellation of a pending retrieval op
274 */
275 static void fscache_do_cancel_retrieval(struct fscache_operation *_op)
276 {
277 struct fscache_retrieval *op =
278 container_of(_op, struct fscache_retrieval, op);
279
280 atomic_set(&op->n_pages, 0);
281 }
282
283 /*
284 * release a retrieval op reference
285 */
286 static void fscache_release_retrieval_op(struct fscache_operation *_op)
287 {
288 struct fscache_retrieval *op =
289 container_of(_op, struct fscache_retrieval, op);
290
291 _enter("{OP%x}", op->op.debug_id);
292
293 ASSERTIFCMP(op->op.state != FSCACHE_OP_ST_INITIALISED,
294 atomic_read(&op->n_pages), ==, 0);
295
296 fscache_hist(fscache_retrieval_histogram, op->start_time);
297 if (op->context)
298 fscache_put_context(op->cookie, op->context);
299
300 _leave("");
301 }
302
303 /*
304 * allocate a retrieval op
305 */
306 static struct fscache_retrieval *fscache_alloc_retrieval(
307 struct fscache_cookie *cookie,
308 struct address_space *mapping,
309 fscache_rw_complete_t end_io_func,
310 void *context)
311 {
312 struct fscache_retrieval *op;
313
314 /* allocate a retrieval operation and attempt to submit it */
315 op = kzalloc(sizeof(*op), GFP_NOIO);
316 if (!op) {
317 fscache_stat(&fscache_n_retrievals_nomem);
318 return NULL;
319 }
320
321 fscache_operation_init(cookie, &op->op, NULL,
322 fscache_do_cancel_retrieval,
323 fscache_release_retrieval_op);
324 op->op.flags = FSCACHE_OP_MYTHREAD |
325 (1UL << FSCACHE_OP_WAITING) |
326 (1UL << FSCACHE_OP_UNUSE_COOKIE);
327 op->cookie = cookie;
328 op->mapping = mapping;
329 op->end_io_func = end_io_func;
330 op->context = context;
331 op->start_time = jiffies;
332 INIT_LIST_HEAD(&op->to_do);
333
334 /* Pin the netfs read context in case we need to do the actual netfs
335 * read because we've encountered a cache read failure.
336 */
337 if (context)
338 fscache_get_context(op->cookie, context);
339 return op;
340 }
341
342 /*
343 * wait for a deferred lookup to complete
344 */
345 int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie)
346 {
347 unsigned long jif;
348
349 _enter("");
350
351 if (!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)) {
352 _leave(" = 0 [imm]");
353 return 0;
354 }
355
356 fscache_stat(&fscache_n_retrievals_wait);
357
358 jif = jiffies;
359 if (wait_on_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP,
360 TASK_INTERRUPTIBLE) != 0) {
361 fscache_stat(&fscache_n_retrievals_intr);
362 _leave(" = -ERESTARTSYS");
363 return -ERESTARTSYS;
364 }
365
366 ASSERT(!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags));
367
368 smp_rmb();
369 fscache_hist(fscache_retrieval_delay_histogram, jif);
370 _leave(" = 0 [dly]");
371 return 0;
372 }
373
374 /*
375 * wait for an object to become active (or dead)
376 */
377 int fscache_wait_for_operation_activation(struct fscache_object *object,
378 struct fscache_operation *op,
379 atomic_t *stat_op_waits,
380 atomic_t *stat_object_dead)
381 {
382 int ret;
383
384 if (!test_bit(FSCACHE_OP_WAITING, &op->flags))
385 goto check_if_dead;
386
387 _debug(">>> WT");
388 if (stat_op_waits)
389 fscache_stat(stat_op_waits);
390 if (wait_on_bit(&op->flags, FSCACHE_OP_WAITING,
391 TASK_INTERRUPTIBLE) != 0) {
392 trace_fscache_op(object->cookie, op, fscache_op_signal);
393 ret = fscache_cancel_op(op, false);
394 if (ret == 0)
395 return -ERESTARTSYS;
396
397 /* it's been removed from the pending queue by another party,
398 * so we should get to run shortly */
399 wait_on_bit(&op->flags, FSCACHE_OP_WAITING,
400 TASK_UNINTERRUPTIBLE);
401 }
402 _debug("<<< GO");
403
404 check_if_dead:
405 if (op->state == FSCACHE_OP_ST_CANCELLED) {
406 if (stat_object_dead)
407 fscache_stat(stat_object_dead);
408 _leave(" = -ENOBUFS [cancelled]");
409 return -ENOBUFS;
410 }
411 if (unlikely(fscache_object_is_dying(object) ||
412 fscache_cache_is_broken(object))) {
413 enum fscache_operation_state state = op->state;
414 trace_fscache_op(object->cookie, op, fscache_op_signal);
415 fscache_cancel_op(op, true);
416 if (stat_object_dead)
417 fscache_stat(stat_object_dead);
418 _leave(" = -ENOBUFS [obj dead %d]", state);
419 return -ENOBUFS;
420 }
421 return 0;
422 }
423
424 /*
425 * read a page from the cache or allocate a block in which to store it
426 * - we return:
427 * -ENOMEM - out of memory, nothing done
428 * -ERESTARTSYS - interrupted
429 * -ENOBUFS - no backing object available in which to cache the block
430 * -ENODATA - no data available in the backing object for this block
431 * 0 - dispatched a read - it'll call end_io_func() when finished
432 */
433 int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
434 struct page *page,
435 fscache_rw_complete_t end_io_func,
436 void *context,
437 gfp_t gfp)
438 {
439 struct fscache_retrieval *op;
440 struct fscache_object *object;
441 bool wake_cookie = false;
442 int ret;
443
444 _enter("%p,%p,,,", cookie, page);
445
446 fscache_stat(&fscache_n_retrievals);
447
448 if (hlist_empty(&cookie->backing_objects))
449 goto nobufs;
450
451 if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
452 _leave(" = -ENOBUFS [invalidating]");
453 return -ENOBUFS;
454 }
455
456 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
457 ASSERTCMP(page, !=, NULL);
458
459 if (fscache_wait_for_deferred_lookup(cookie) < 0)
460 return -ERESTARTSYS;
461
462 op = fscache_alloc_retrieval(cookie, page->mapping,
463 end_io_func, context);
464 if (!op) {
465 _leave(" = -ENOMEM");
466 return -ENOMEM;
467 }
468 atomic_set(&op->n_pages, 1);
469 trace_fscache_page_op(cookie, page, &op->op, fscache_page_op_retr_one);
470
471 spin_lock(&cookie->lock);
472
473 if (!fscache_cookie_enabled(cookie) ||
474 hlist_empty(&cookie->backing_objects))
475 goto nobufs_unlock;
476 object = hlist_entry(cookie->backing_objects.first,
477 struct fscache_object, cookie_link);
478
479 ASSERT(test_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags));
480
481 __fscache_use_cookie(cookie);
482 atomic_inc(&object->n_reads);
483 __set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
484
485 if (fscache_submit_op(object, &op->op) < 0)
486 goto nobufs_unlock_dec;
487 spin_unlock(&cookie->lock);
488
489 fscache_stat(&fscache_n_retrieval_ops);
490
491 /* we wait for the operation to become active, and then process it
492 * *here*, in this thread, and not in the thread pool */
493 ret = fscache_wait_for_operation_activation(
494 object, &op->op,
495 __fscache_stat(&fscache_n_retrieval_op_waits),
496 __fscache_stat(&fscache_n_retrievals_object_dead));
497 if (ret < 0)
498 goto error;
499
500 /* ask the cache to honour the operation */
501 if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) {
502 fscache_stat(&fscache_n_cop_allocate_page);
503 ret = object->cache->ops->allocate_page(op, page, gfp);
504 fscache_stat_d(&fscache_n_cop_allocate_page);
505 if (ret == 0)
506 ret = -ENODATA;
507 } else {
508 fscache_stat(&fscache_n_cop_read_or_alloc_page);
509 ret = object->cache->ops->read_or_alloc_page(op, page, gfp);
510 fscache_stat_d(&fscache_n_cop_read_or_alloc_page);
511 }
512
513 error:
514 if (ret == -ENOMEM)
515 fscache_stat(&fscache_n_retrievals_nomem);
516 else if (ret == -ERESTARTSYS)
517 fscache_stat(&fscache_n_retrievals_intr);
518 else if (ret == -ENODATA)
519 fscache_stat(&fscache_n_retrievals_nodata);
520 else if (ret < 0)
521 fscache_stat(&fscache_n_retrievals_nobufs);
522 else
523 fscache_stat(&fscache_n_retrievals_ok);
524
525 fscache_put_retrieval(op);
526 _leave(" = %d", ret);
527 return ret;
528
529 nobufs_unlock_dec:
530 atomic_dec(&object->n_reads);
531 wake_cookie = __fscache_unuse_cookie(cookie);
532 nobufs_unlock:
533 spin_unlock(&cookie->lock);
534 if (wake_cookie)
535 __fscache_wake_unused_cookie(cookie);
536 fscache_put_retrieval(op);
537 nobufs:
538 fscache_stat(&fscache_n_retrievals_nobufs);
539 _leave(" = -ENOBUFS");
540 return -ENOBUFS;
541 }
542 EXPORT_SYMBOL(__fscache_read_or_alloc_page);
543
544 /*
545 * read a list of page from the cache or allocate a block in which to store
546 * them
547 * - we return:
548 * -ENOMEM - out of memory, some pages may be being read
549 * -ERESTARTSYS - interrupted, some pages may be being read
550 * -ENOBUFS - no backing object or space available in which to cache any
551 * pages not being read
552 * -ENODATA - no data available in the backing object for some or all of
553 * the pages
554 * 0 - dispatched a read on all pages
555 *
556 * end_io_func() will be called for each page read from the cache as it is
557 * finishes being read
558 *
559 * any pages for which a read is dispatched will be removed from pages and
560 * nr_pages
561 */
562 int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
563 struct address_space *mapping,
564 struct list_head *pages,
565 unsigned *nr_pages,
566 fscache_rw_complete_t end_io_func,
567 void *context,
568 gfp_t gfp)
569 {
570 struct fscache_retrieval *op;
571 struct fscache_object *object;
572 bool wake_cookie = false;
573 int ret;
574
575 _enter("%p,,%d,,,", cookie, *nr_pages);
576
577 fscache_stat(&fscache_n_retrievals);
578
579 if (hlist_empty(&cookie->backing_objects))
580 goto nobufs;
581
582 if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
583 _leave(" = -ENOBUFS [invalidating]");
584 return -ENOBUFS;
585 }
586
587 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
588 ASSERTCMP(*nr_pages, >, 0);
589 ASSERT(!list_empty(pages));
590
591 if (fscache_wait_for_deferred_lookup(cookie) < 0)
592 return -ERESTARTSYS;
593
594 op = fscache_alloc_retrieval(cookie, mapping, end_io_func, context);
595 if (!op)
596 return -ENOMEM;
597 atomic_set(&op->n_pages, *nr_pages);
598 trace_fscache_page_op(cookie, NULL, &op->op, fscache_page_op_retr_multi);
599
600 spin_lock(&cookie->lock);
601
602 if (!fscache_cookie_enabled(cookie) ||
603 hlist_empty(&cookie->backing_objects))
604 goto nobufs_unlock;
605 object = hlist_entry(cookie->backing_objects.first,
606 struct fscache_object, cookie_link);
607
608 __fscache_use_cookie(cookie);
609 atomic_inc(&object->n_reads);
610 __set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
611
612 if (fscache_submit_op(object, &op->op) < 0)
613 goto nobufs_unlock_dec;
614 spin_unlock(&cookie->lock);
615
616 fscache_stat(&fscache_n_retrieval_ops);
617
618 /* we wait for the operation to become active, and then process it
619 * *here*, in this thread, and not in the thread pool */
620 ret = fscache_wait_for_operation_activation(
621 object, &op->op,
622 __fscache_stat(&fscache_n_retrieval_op_waits),
623 __fscache_stat(&fscache_n_retrievals_object_dead));
624 if (ret < 0)
625 goto error;
626
627 /* ask the cache to honour the operation */
628 if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) {
629 fscache_stat(&fscache_n_cop_allocate_pages);
630 ret = object->cache->ops->allocate_pages(
631 op, pages, nr_pages, gfp);
632 fscache_stat_d(&fscache_n_cop_allocate_pages);
633 } else {
634 fscache_stat(&fscache_n_cop_read_or_alloc_pages);
635 ret = object->cache->ops->read_or_alloc_pages(
636 op, pages, nr_pages, gfp);
637 fscache_stat_d(&fscache_n_cop_read_or_alloc_pages);
638 }
639
640 error:
641 if (ret == -ENOMEM)
642 fscache_stat(&fscache_n_retrievals_nomem);
643 else if (ret == -ERESTARTSYS)
644 fscache_stat(&fscache_n_retrievals_intr);
645 else if (ret == -ENODATA)
646 fscache_stat(&fscache_n_retrievals_nodata);
647 else if (ret < 0)
648 fscache_stat(&fscache_n_retrievals_nobufs);
649 else
650 fscache_stat(&fscache_n_retrievals_ok);
651
652 fscache_put_retrieval(op);
653 _leave(" = %d", ret);
654 return ret;
655
656 nobufs_unlock_dec:
657 atomic_dec(&object->n_reads);
658 wake_cookie = __fscache_unuse_cookie(cookie);
659 nobufs_unlock:
660 spin_unlock(&cookie->lock);
661 fscache_put_retrieval(op);
662 if (wake_cookie)
663 __fscache_wake_unused_cookie(cookie);
664 nobufs:
665 fscache_stat(&fscache_n_retrievals_nobufs);
666 _leave(" = -ENOBUFS");
667 return -ENOBUFS;
668 }
669 EXPORT_SYMBOL(__fscache_read_or_alloc_pages);
670
671 /*
672 * allocate a block in the cache on which to store a page
673 * - we return:
674 * -ENOMEM - out of memory, nothing done
675 * -ERESTARTSYS - interrupted
676 * -ENOBUFS - no backing object available in which to cache the block
677 * 0 - block allocated
678 */
679 int __fscache_alloc_page(struct fscache_cookie *cookie,
680 struct page *page,
681 gfp_t gfp)
682 {
683 struct fscache_retrieval *op;
684 struct fscache_object *object;
685 bool wake_cookie = false;
686 int ret;
687
688 _enter("%p,%p,,,", cookie, page);
689
690 fscache_stat(&fscache_n_allocs);
691
692 if (hlist_empty(&cookie->backing_objects))
693 goto nobufs;
694
695 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
696 ASSERTCMP(page, !=, NULL);
697
698 if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
699 _leave(" = -ENOBUFS [invalidating]");
700 return -ENOBUFS;
701 }
702
703 if (fscache_wait_for_deferred_lookup(cookie) < 0)
704 return -ERESTARTSYS;
705
706 op = fscache_alloc_retrieval(cookie, page->mapping, NULL, NULL);
707 if (!op)
708 return -ENOMEM;
709 atomic_set(&op->n_pages, 1);
710 trace_fscache_page_op(cookie, page, &op->op, fscache_page_op_alloc_one);
711
712 spin_lock(&cookie->lock);
713
714 if (!fscache_cookie_enabled(cookie) ||
715 hlist_empty(&cookie->backing_objects))
716 goto nobufs_unlock;
717 object = hlist_entry(cookie->backing_objects.first,
718 struct fscache_object, cookie_link);
719
720 __fscache_use_cookie(cookie);
721 if (fscache_submit_op(object, &op->op) < 0)
722 goto nobufs_unlock_dec;
723 spin_unlock(&cookie->lock);
724
725 fscache_stat(&fscache_n_alloc_ops);
726
727 ret = fscache_wait_for_operation_activation(
728 object, &op->op,
729 __fscache_stat(&fscache_n_alloc_op_waits),
730 __fscache_stat(&fscache_n_allocs_object_dead));
731 if (ret < 0)
732 goto error;
733
734 /* ask the cache to honour the operation */
735 fscache_stat(&fscache_n_cop_allocate_page);
736 ret = object->cache->ops->allocate_page(op, page, gfp);
737 fscache_stat_d(&fscache_n_cop_allocate_page);
738
739 error:
740 if (ret == -ERESTARTSYS)
741 fscache_stat(&fscache_n_allocs_intr);
742 else if (ret < 0)
743 fscache_stat(&fscache_n_allocs_nobufs);
744 else
745 fscache_stat(&fscache_n_allocs_ok);
746
747 fscache_put_retrieval(op);
748 _leave(" = %d", ret);
749 return ret;
750
751 nobufs_unlock_dec:
752 wake_cookie = __fscache_unuse_cookie(cookie);
753 nobufs_unlock:
754 spin_unlock(&cookie->lock);
755 fscache_put_retrieval(op);
756 if (wake_cookie)
757 __fscache_wake_unused_cookie(cookie);
758 nobufs:
759 fscache_stat(&fscache_n_allocs_nobufs);
760 _leave(" = -ENOBUFS");
761 return -ENOBUFS;
762 }
763 EXPORT_SYMBOL(__fscache_alloc_page);
764
765 /*
766 * Unmark pages allocate in the readahead code path (via:
767 * fscache_readpages_or_alloc) after delegating to the base filesystem
768 */
769 void __fscache_readpages_cancel(struct fscache_cookie *cookie,
770 struct list_head *pages)
771 {
772 struct page *page;
773
774 list_for_each_entry(page, pages, lru) {
775 if (PageFsCache(page))
776 __fscache_uncache_page(cookie, page);
777 }
778 }
779 EXPORT_SYMBOL(__fscache_readpages_cancel);
780
781 /*
782 * release a write op reference
783 */
784 static void fscache_release_write_op(struct fscache_operation *_op)
785 {
786 _enter("{OP%x}", _op->debug_id);
787 }
788
789 /*
790 * perform the background storage of a page into the cache
791 */
792 static void fscache_write_op(struct fscache_operation *_op)
793 {
794 struct fscache_storage *op =
795 container_of(_op, struct fscache_storage, op);
796 struct fscache_object *object = op->op.object;
797 struct fscache_cookie *cookie;
798 struct page *page;
799 unsigned n;
800 void *results[1];
801 int ret;
802
803 _enter("{OP%x,%d}", op->op.debug_id, atomic_read(&op->op.usage));
804
805 again:
806 spin_lock(&object->lock);
807 cookie = object->cookie;
808
809 if (!fscache_object_is_active(object)) {
810 /* If we get here, then the on-disk cache object likely no
811 * longer exists, so we should just cancel this write
812 * operation.
813 */
814 spin_unlock(&object->lock);
815 fscache_op_complete(&op->op, true);
816 _leave(" [inactive]");
817 return;
818 }
819
820 if (!cookie) {
821 /* If we get here, then the cookie belonging to the object was
822 * detached, probably by the cookie being withdrawn due to
823 * memory pressure, which means that the pages we might write
824 * to the cache from no longer exist - therefore, we can just
825 * cancel this write operation.
826 */
827 spin_unlock(&object->lock);
828 fscache_op_complete(&op->op, true);
829 _leave(" [cancel] op{f=%lx s=%u} obj{s=%s f=%lx}",
830 _op->flags, _op->state, object->state->short_name,
831 object->flags);
832 return;
833 }
834
835 spin_lock(&cookie->stores_lock);
836
837 fscache_stat(&fscache_n_store_calls);
838
839 /* find a page to store */
840 results[0] = NULL;
841 page = NULL;
842 n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0, 1,
843 FSCACHE_COOKIE_PENDING_TAG);
844 trace_fscache_gang_lookup(cookie, &op->op, results, n, op->store_limit);
845 if (n != 1)
846 goto superseded;
847 page = results[0];
848 _debug("gang %d [%lx]", n, page->index);
849
850 radix_tree_tag_set(&cookie->stores, page->index,
851 FSCACHE_COOKIE_STORING_TAG);
852 radix_tree_tag_clear(&cookie->stores, page->index,
853 FSCACHE_COOKIE_PENDING_TAG);
854 trace_fscache_page(cookie, page, fscache_page_radix_pend2store);
855
856 spin_unlock(&cookie->stores_lock);
857 spin_unlock(&object->lock);
858
859 if (page->index >= op->store_limit)
860 goto discard_page;
861
862 fscache_stat(&fscache_n_store_pages);
863 fscache_stat(&fscache_n_cop_write_page);
864 ret = object->cache->ops->write_page(op, page);
865 fscache_stat_d(&fscache_n_cop_write_page);
866 trace_fscache_wrote_page(cookie, page, &op->op, ret);
867 fscache_end_page_write(object, page);
868 if (ret < 0) {
869 fscache_abort_object(object);
870 fscache_op_complete(&op->op, true);
871 } else {
872 fscache_enqueue_operation(&op->op);
873 }
874
875 _leave("");
876 return;
877
878 discard_page:
879 fscache_stat(&fscache_n_store_pages_over_limit);
880 trace_fscache_wrote_page(cookie, page, &op->op, -ENOBUFS);
881 fscache_end_page_write(object, page);
882 goto again;
883
884 superseded:
885 /* this writer is going away and there aren't any more things to
886 * write */
887 _debug("cease");
888 spin_unlock(&cookie->stores_lock);
889 clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
890 spin_unlock(&object->lock);
891 fscache_op_complete(&op->op, false);
892 _leave("");
893 }
894
895 /*
896 * Clear the pages pending writing for invalidation
897 */
898 void fscache_invalidate_writes(struct fscache_cookie *cookie)
899 {
900 struct page *page;
901 void *results[16];
902 int n, i;
903
904 _enter("");
905
906 for (;;) {
907 spin_lock(&cookie->stores_lock);
908 n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0,
909 ARRAY_SIZE(results),
910 FSCACHE_COOKIE_PENDING_TAG);
911 if (n == 0) {
912 spin_unlock(&cookie->stores_lock);
913 break;
914 }
915
916 for (i = n - 1; i >= 0; i--) {
917 page = results[i];
918 radix_tree_delete(&cookie->stores, page->index);
919 trace_fscache_page(cookie, page, fscache_page_radix_delete);
920 trace_fscache_page(cookie, page, fscache_page_inval);
921 }
922
923 spin_unlock(&cookie->stores_lock);
924
925 for (i = n - 1; i >= 0; i--)
926 put_page(results[i]);
927 }
928
929 wake_up_bit(&cookie->flags, 0);
930 trace_fscache_wake_cookie(cookie);
931
932 _leave("");
933 }
934
935 /*
936 * request a page be stored in the cache
937 * - returns:
938 * -ENOMEM - out of memory, nothing done
939 * -ENOBUFS - no backing object available in which to cache the page
940 * 0 - dispatched a write - it'll call end_io_func() when finished
941 *
942 * if the cookie still has a backing object at this point, that object can be
943 * in one of a few states with respect to storage processing:
944 *
945 * (1) negative lookup, object not yet created (FSCACHE_COOKIE_CREATING is
946 * set)
947 *
948 * (a) no writes yet
949 *
950 * (b) writes deferred till post-creation (mark page for writing and
951 * return immediately)
952 *
953 * (2) negative lookup, object created, initial fill being made from netfs
954 *
955 * (a) fill point not yet reached this page (mark page for writing and
956 * return)
957 *
958 * (b) fill point passed this page (queue op to store this page)
959 *
960 * (3) object extant (queue op to store this page)
961 *
962 * any other state is invalid
963 */
964 int __fscache_write_page(struct fscache_cookie *cookie,
965 struct page *page,
966 loff_t object_size,
967 gfp_t gfp)
968 {
969 struct fscache_storage *op;
970 struct fscache_object *object;
971 bool wake_cookie = false;
972 int ret;
973
974 _enter("%p,%x,", cookie, (u32) page->flags);
975
976 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
977 ASSERT(PageFsCache(page));
978
979 fscache_stat(&fscache_n_stores);
980
981 if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
982 _leave(" = -ENOBUFS [invalidating]");
983 return -ENOBUFS;
984 }
985
986 op = kzalloc(sizeof(*op), GFP_NOIO | __GFP_NOMEMALLOC | __GFP_NORETRY);
987 if (!op)
988 goto nomem;
989
990 fscache_operation_init(cookie, &op->op, fscache_write_op, NULL,
991 fscache_release_write_op);
992 op->op.flags = FSCACHE_OP_ASYNC |
993 (1 << FSCACHE_OP_WAITING) |
994 (1 << FSCACHE_OP_UNUSE_COOKIE);
995
996 ret = radix_tree_maybe_preload(gfp & ~__GFP_HIGHMEM);
997 if (ret < 0)
998 goto nomem_free;
999
1000 trace_fscache_page_op(cookie, page, &op->op, fscache_page_op_write_one);
1001
1002 ret = -ENOBUFS;
1003 spin_lock(&cookie->lock);
1004
1005 if (!fscache_cookie_enabled(cookie) ||
1006 hlist_empty(&cookie->backing_objects))
1007 goto nobufs;
1008 object = hlist_entry(cookie->backing_objects.first,
1009 struct fscache_object, cookie_link);
1010 if (test_bit(FSCACHE_IOERROR, &object->cache->flags))
1011 goto nobufs;
1012
1013 trace_fscache_page(cookie, page, fscache_page_write);
1014
1015 /* add the page to the pending-storage radix tree on the backing
1016 * object */
1017 spin_lock(&object->lock);
1018
1019 if (object->store_limit_l != object_size)
1020 fscache_set_store_limit(object, object_size);
1021
1022 spin_lock(&cookie->stores_lock);
1023
1024 _debug("store limit %llx", (unsigned long long) object->store_limit);
1025
1026 ret = radix_tree_insert(&cookie->stores, page->index, page);
1027 if (ret < 0) {
1028 if (ret == -EEXIST)
1029 goto already_queued;
1030 _debug("insert failed %d", ret);
1031 goto nobufs_unlock_obj;
1032 }
1033
1034 trace_fscache_page(cookie, page, fscache_page_radix_insert);
1035 radix_tree_tag_set(&cookie->stores, page->index,
1036 FSCACHE_COOKIE_PENDING_TAG);
1037 trace_fscache_page(cookie, page, fscache_page_radix_set_pend);
1038 get_page(page);
1039
1040 /* we only want one writer at a time, but we do need to queue new
1041 * writers after exclusive ops */
1042 if (test_and_set_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags))
1043 goto already_pending;
1044
1045 spin_unlock(&cookie->stores_lock);
1046 spin_unlock(&object->lock);
1047
1048 op->op.debug_id = atomic_inc_return(&fscache_op_debug_id);
1049 op->store_limit = object->store_limit;
1050
1051 __fscache_use_cookie(cookie);
1052 if (fscache_submit_op(object, &op->op) < 0)
1053 goto submit_failed;
1054
1055 spin_unlock(&cookie->lock);
1056 radix_tree_preload_end();
1057 fscache_stat(&fscache_n_store_ops);
1058 fscache_stat(&fscache_n_stores_ok);
1059
1060 /* the work queue now carries its own ref on the object */
1061 fscache_put_operation(&op->op);
1062 _leave(" = 0");
1063 return 0;
1064
1065 already_queued:
1066 fscache_stat(&fscache_n_stores_again);
1067 already_pending:
1068 spin_unlock(&cookie->stores_lock);
1069 spin_unlock(&object->lock);
1070 spin_unlock(&cookie->lock);
1071 radix_tree_preload_end();
1072 fscache_put_operation(&op->op);
1073 fscache_stat(&fscache_n_stores_ok);
1074 _leave(" = 0");
1075 return 0;
1076
1077 submit_failed:
1078 spin_lock(&cookie->stores_lock);
1079 radix_tree_delete(&cookie->stores, page->index);
1080 trace_fscache_page(cookie, page, fscache_page_radix_delete);
1081 spin_unlock(&cookie->stores_lock);
1082 wake_cookie = __fscache_unuse_cookie(cookie);
1083 put_page(page);
1084 ret = -ENOBUFS;
1085 goto nobufs;
1086
1087 nobufs_unlock_obj:
1088 spin_unlock(&cookie->stores_lock);
1089 spin_unlock(&object->lock);
1090 nobufs:
1091 spin_unlock(&cookie->lock);
1092 radix_tree_preload_end();
1093 fscache_put_operation(&op->op);
1094 if (wake_cookie)
1095 __fscache_wake_unused_cookie(cookie);
1096 fscache_stat(&fscache_n_stores_nobufs);
1097 _leave(" = -ENOBUFS");
1098 return -ENOBUFS;
1099
1100 nomem_free:
1101 fscache_put_operation(&op->op);
1102 nomem:
1103 fscache_stat(&fscache_n_stores_oom);
1104 _leave(" = -ENOMEM");
1105 return -ENOMEM;
1106 }
1107 EXPORT_SYMBOL(__fscache_write_page);
1108
1109 /*
1110 * remove a page from the cache
1111 */
1112 void __fscache_uncache_page(struct fscache_cookie *cookie, struct page *page)
1113 {
1114 struct fscache_object *object;
1115
1116 _enter(",%p", page);
1117
1118 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
1119 ASSERTCMP(page, !=, NULL);
1120
1121 fscache_stat(&fscache_n_uncaches);
1122
1123 /* cache withdrawal may beat us to it */
1124 if (!PageFsCache(page))
1125 goto done;
1126
1127 trace_fscache_page(cookie, page, fscache_page_uncache);
1128
1129 /* get the object */
1130 spin_lock(&cookie->lock);
1131
1132 if (hlist_empty(&cookie->backing_objects)) {
1133 ClearPageFsCache(page);
1134 goto done_unlock;
1135 }
1136
1137 object = hlist_entry(cookie->backing_objects.first,
1138 struct fscache_object, cookie_link);
1139
1140 /* there might now be stuff on disk we could read */
1141 clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
1142
1143 /* only invoke the cache backend if we managed to mark the page
1144 * uncached here; this deals with synchronisation vs withdrawal */
1145 if (TestClearPageFsCache(page) &&
1146 object->cache->ops->uncache_page) {
1147 /* the cache backend releases the cookie lock */
1148 fscache_stat(&fscache_n_cop_uncache_page);
1149 object->cache->ops->uncache_page(object, page);
1150 fscache_stat_d(&fscache_n_cop_uncache_page);
1151 goto done;
1152 }
1153
1154 done_unlock:
1155 spin_unlock(&cookie->lock);
1156 done:
1157 _leave("");
1158 }
1159 EXPORT_SYMBOL(__fscache_uncache_page);
1160
1161 /**
1162 * fscache_mark_page_cached - Mark a page as being cached
1163 * @op: The retrieval op pages are being marked for
1164 * @page: The page to be marked
1165 *
1166 * Mark a netfs page as being cached. After this is called, the netfs
1167 * must call fscache_uncache_page() to remove the mark.
1168 */
1169 void fscache_mark_page_cached(struct fscache_retrieval *op, struct page *page)
1170 {
1171 struct fscache_cookie *cookie = op->op.object->cookie;
1172
1173 #ifdef CONFIG_FSCACHE_STATS
1174 atomic_inc(&fscache_n_marks);
1175 #endif
1176
1177 trace_fscache_page(cookie, page, fscache_page_cached);
1178
1179 _debug("- mark %p{%lx}", page, page->index);
1180 if (TestSetPageFsCache(page)) {
1181 static bool once_only;
1182 if (!once_only) {
1183 once_only = true;
1184 pr_warn("Cookie type %s marked page %lx multiple times\n",
1185 cookie->def->name, page->index);
1186 }
1187 }
1188
1189 if (cookie->def->mark_page_cached)
1190 cookie->def->mark_page_cached(cookie->netfs_data,
1191 op->mapping, page);
1192 }
1193 EXPORT_SYMBOL(fscache_mark_page_cached);
1194
1195 /**
1196 * fscache_mark_pages_cached - Mark pages as being cached
1197 * @op: The retrieval op pages are being marked for
1198 * @pagevec: The pages to be marked
1199 *
1200 * Mark a bunch of netfs pages as being cached. After this is called,
1201 * the netfs must call fscache_uncache_page() to remove the mark.
1202 */
1203 void fscache_mark_pages_cached(struct fscache_retrieval *op,
1204 struct pagevec *pagevec)
1205 {
1206 unsigned long loop;
1207
1208 for (loop = 0; loop < pagevec->nr; loop++)
1209 fscache_mark_page_cached(op, pagevec->pages[loop]);
1210
1211 pagevec_reinit(pagevec);
1212 }
1213 EXPORT_SYMBOL(fscache_mark_pages_cached);
1214
1215 /*
1216 * Uncache all the pages in an inode that are marked PG_fscache, assuming them
1217 * to be associated with the given cookie.
1218 */
1219 void __fscache_uncache_all_inode_pages(struct fscache_cookie *cookie,
1220 struct inode *inode)
1221 {
1222 struct address_space *mapping = inode->i_mapping;
1223 struct pagevec pvec;
1224 pgoff_t next;
1225 int i;
1226
1227 _enter("%p,%p", cookie, inode);
1228
1229 if (!mapping || mapping->nrpages == 0) {
1230 _leave(" [no pages]");
1231 return;
1232 }
1233
1234 pagevec_init(&pvec);
1235 next = 0;
1236 do {
1237 if (!pagevec_lookup(&pvec, mapping, &next))
1238 break;
1239 for (i = 0; i < pagevec_count(&pvec); i++) {
1240 struct page *page = pvec.pages[i];
1241 if (PageFsCache(page)) {
1242 __fscache_wait_on_page_write(cookie, page);
1243 __fscache_uncache_page(cookie, page);
1244 }
1245 }
1246 pagevec_release(&pvec);
1247 cond_resched();
1248 } while (next);
1249
1250 _leave("");
1251 }
1252 EXPORT_SYMBOL(__fscache_uncache_all_inode_pages);
1253
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