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