blob: 723b889fd219f5eb6a6f360b807ac8e45881f00a [file] [log] [blame]
David Howellsb5108822009-04-03 16:42:39 +01001/* 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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090017#include <linux/slab.h>
David Howellsb5108822009-04-03 16:42:39 +010018#include "internal.h"
19
20/*
21 * check to see if a page is being written to the cache
22 */
23bool __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}
33EXPORT_SYMBOL(__fscache_check_page_write);
34
35/*
36 * wait for a page to finish being written to the cache
37 */
38void __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}
44EXPORT_SYMBOL(__fscache_wait_on_page_write);
45
46/*
David Howells201a1542009-11-19 18:11:35 +000047 * 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 */
50bool __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
106page_busy:
107 /* we might want to wait here, but that could deadlock the allocator as
108 * the slow-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}
113EXPORT_SYMBOL(__fscache_maybe_release_page);
114
115/*
David Howellsb5108822009-04-03 16:42:39 +0100116 * note that a page has finished being written to the cache
117 */
David Howells1bccf512009-11-19 18:11:25 +0000118static void fscache_end_page_write(struct fscache_object *object,
119 struct page *page)
David Howellsb5108822009-04-03 16:42:39 +0100120{
David Howells1bccf512009-11-19 18:11:25 +0000121 struct fscache_cookie *cookie;
122 struct page *xpage = NULL;
David Howellsb5108822009-04-03 16:42:39 +0100123
David Howells1bccf512009-11-19 18:11:25 +0000124 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);
David Howells201a1542009-11-19 18:11:35 +0000130 radix_tree_tag_clear(&cookie->stores, page->index,
131 FSCACHE_COOKIE_STORING_TAG);
David Howells285e7282009-11-19 18:11:29 +0000132 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 }
David Howells1bccf512009-11-19 18:11:25 +0000137 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);
David Howellsb5108822009-04-03 16:42:39 +0100143}
144
145/*
146 * actually apply the changed attributes to a cache object
147 */
148static void fscache_attr_changed_op(struct fscache_operation *op)
149{
150 struct fscache_object *object = op->object;
David Howells440f0af2009-11-19 18:11:01 +0000151 int ret;
David Howellsb5108822009-04-03 16:42:39 +0100152
153 _enter("{OBJ%x OP%x}", object->debug_id, op->debug_id);
154
155 fscache_stat(&fscache_n_attr_changed_calls);
156
David Howells440f0af2009-11-19 18:11:01 +0000157 if (fscache_object_is_active(object)) {
158 fscache_set_op_state(op, "CallFS");
David Howells52bd75f2009-11-19 18:11:08 +0000159 fscache_stat(&fscache_n_cop_attr_changed);
David Howells440f0af2009-11-19 18:11:01 +0000160 ret = object->cache->ops->attr_changed(object);
David Howells52bd75f2009-11-19 18:11:08 +0000161 fscache_stat_d(&fscache_n_cop_attr_changed);
David Howells440f0af2009-11-19 18:11:01 +0000162 fscache_set_op_state(op, "Done");
163 if (ret < 0)
164 fscache_abort_object(object);
165 }
David Howellsb5108822009-04-03 16:42:39 +0100166
167 _leave("");
168}
169
170/*
171 * notification that the attributes on an object have changed
172 */
173int __fscache_attr_changed(struct fscache_cookie *cookie)
174{
175 struct fscache_operation *op;
176 struct fscache_object *object;
177
178 _enter("%p", cookie);
179
180 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
181
182 fscache_stat(&fscache_n_attr_changed);
183
184 op = kzalloc(sizeof(*op), GFP_KERNEL);
185 if (!op) {
186 fscache_stat(&fscache_n_attr_changed_nomem);
187 _leave(" = -ENOMEM");
188 return -ENOMEM;
189 }
190
191 fscache_operation_init(op, NULL);
192 fscache_operation_init_slow(op, fscache_attr_changed_op);
193 op->flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_EXCLUSIVE);
David Howells440f0af2009-11-19 18:11:01 +0000194 fscache_set_op_name(op, "Attr");
David Howellsb5108822009-04-03 16:42:39 +0100195
196 spin_lock(&cookie->lock);
197
198 if (hlist_empty(&cookie->backing_objects))
199 goto nobufs;
200 object = hlist_entry(cookie->backing_objects.first,
201 struct fscache_object, cookie_link);
202
203 if (fscache_submit_exclusive_op(object, op) < 0)
204 goto nobufs;
205 spin_unlock(&cookie->lock);
206 fscache_stat(&fscache_n_attr_changed_ok);
207 fscache_put_operation(op);
208 _leave(" = 0");
209 return 0;
210
211nobufs:
212 spin_unlock(&cookie->lock);
213 kfree(op);
214 fscache_stat(&fscache_n_attr_changed_nobufs);
215 _leave(" = %d", -ENOBUFS);
216 return -ENOBUFS;
217}
218EXPORT_SYMBOL(__fscache_attr_changed);
219
220/*
221 * handle secondary execution given to a retrieval op on behalf of the
222 * cache
223 */
224static void fscache_retrieval_work(struct work_struct *work)
225{
226 struct fscache_retrieval *op =
227 container_of(work, struct fscache_retrieval, op.fast_work);
228 unsigned long start;
229
230 _enter("{OP%x}", op->op.debug_id);
231
232 start = jiffies;
233 op->op.processor(&op->op);
234 fscache_hist(fscache_ops_histogram, start);
235 fscache_put_operation(&op->op);
236}
237
238/*
239 * release a retrieval op reference
240 */
241static void fscache_release_retrieval_op(struct fscache_operation *_op)
242{
243 struct fscache_retrieval *op =
244 container_of(_op, struct fscache_retrieval, op);
245
246 _enter("{OP%x}", op->op.debug_id);
247
248 fscache_hist(fscache_retrieval_histogram, op->start_time);
249 if (op->context)
250 fscache_put_context(op->op.object->cookie, op->context);
251
252 _leave("");
253}
254
255/*
256 * allocate a retrieval op
257 */
258static struct fscache_retrieval *fscache_alloc_retrieval(
259 struct address_space *mapping,
260 fscache_rw_complete_t end_io_func,
261 void *context)
262{
263 struct fscache_retrieval *op;
264
265 /* allocate a retrieval operation and attempt to submit it */
266 op = kzalloc(sizeof(*op), GFP_NOIO);
267 if (!op) {
268 fscache_stat(&fscache_n_retrievals_nomem);
269 return NULL;
270 }
271
272 fscache_operation_init(&op->op, fscache_release_retrieval_op);
273 op->op.flags = FSCACHE_OP_MYTHREAD | (1 << FSCACHE_OP_WAITING);
274 op->mapping = mapping;
275 op->end_io_func = end_io_func;
276 op->context = context;
277 op->start_time = jiffies;
278 INIT_WORK(&op->op.fast_work, fscache_retrieval_work);
279 INIT_LIST_HEAD(&op->to_do);
David Howells440f0af2009-11-19 18:11:01 +0000280 fscache_set_op_name(&op->op, "Retr");
David Howellsb5108822009-04-03 16:42:39 +0100281 return op;
282}
283
284/*
285 * wait for a deferred lookup to complete
286 */
287static int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie)
288{
289 unsigned long jif;
290
291 _enter("");
292
293 if (!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)) {
294 _leave(" = 0 [imm]");
295 return 0;
296 }
297
298 fscache_stat(&fscache_n_retrievals_wait);
299
300 jif = jiffies;
301 if (wait_on_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP,
302 fscache_wait_bit_interruptible,
303 TASK_INTERRUPTIBLE) != 0) {
304 fscache_stat(&fscache_n_retrievals_intr);
305 _leave(" = -ERESTARTSYS");
306 return -ERESTARTSYS;
307 }
308
309 ASSERT(!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags));
310
311 smp_rmb();
312 fscache_hist(fscache_retrieval_delay_histogram, jif);
313 _leave(" = 0 [dly]");
314 return 0;
315}
316
317/*
David Howells60d543c2009-11-19 18:11:45 +0000318 * wait for an object to become active (or dead)
319 */
320static int fscache_wait_for_retrieval_activation(struct fscache_object *object,
321 struct fscache_retrieval *op,
322 atomic_t *stat_op_waits,
323 atomic_t *stat_object_dead)
324{
325 int ret;
326
327 if (!test_bit(FSCACHE_OP_WAITING, &op->op.flags))
328 goto check_if_dead;
329
330 _debug(">>> WT");
331 fscache_stat(stat_op_waits);
332 if (wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
333 fscache_wait_bit_interruptible,
334 TASK_INTERRUPTIBLE) < 0) {
335 ret = fscache_cancel_op(&op->op);
336 if (ret == 0)
337 return -ERESTARTSYS;
338
339 /* it's been removed from the pending queue by another party,
340 * so we should get to run shortly */
341 wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
342 fscache_wait_bit, TASK_UNINTERRUPTIBLE);
343 }
344 _debug("<<< GO");
345
346check_if_dead:
347 if (unlikely(fscache_object_is_dead(object))) {
348 fscache_stat(stat_object_dead);
349 return -ENOBUFS;
350 }
351 return 0;
352}
353
354/*
David Howellsb5108822009-04-03 16:42:39 +0100355 * read a page from the cache or allocate a block in which to store it
356 * - we return:
357 * -ENOMEM - out of memory, nothing done
358 * -ERESTARTSYS - interrupted
359 * -ENOBUFS - no backing object available in which to cache the block
360 * -ENODATA - no data available in the backing object for this block
361 * 0 - dispatched a read - it'll call end_io_func() when finished
362 */
363int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
364 struct page *page,
365 fscache_rw_complete_t end_io_func,
366 void *context,
367 gfp_t gfp)
368{
369 struct fscache_retrieval *op;
370 struct fscache_object *object;
371 int ret;
372
373 _enter("%p,%p,,,", cookie, page);
374
375 fscache_stat(&fscache_n_retrievals);
376
377 if (hlist_empty(&cookie->backing_objects))
378 goto nobufs;
379
380 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
381 ASSERTCMP(page, !=, NULL);
382
383 if (fscache_wait_for_deferred_lookup(cookie) < 0)
384 return -ERESTARTSYS;
385
386 op = fscache_alloc_retrieval(page->mapping, end_io_func, context);
387 if (!op) {
388 _leave(" = -ENOMEM");
389 return -ENOMEM;
390 }
David Howells440f0af2009-11-19 18:11:01 +0000391 fscache_set_op_name(&op->op, "RetrRA1");
David Howellsb5108822009-04-03 16:42:39 +0100392
393 spin_lock(&cookie->lock);
394
395 if (hlist_empty(&cookie->backing_objects))
396 goto nobufs_unlock;
397 object = hlist_entry(cookie->backing_objects.first,
398 struct fscache_object, cookie_link);
399
400 ASSERTCMP(object->state, >, FSCACHE_OBJECT_LOOKING_UP);
401
David Howells4fbf4292009-11-19 18:11:04 +0000402 atomic_inc(&object->n_reads);
403 set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
404
David Howellsb5108822009-04-03 16:42:39 +0100405 if (fscache_submit_op(object, &op->op) < 0)
406 goto nobufs_unlock;
407 spin_unlock(&cookie->lock);
408
409 fscache_stat(&fscache_n_retrieval_ops);
410
411 /* pin the netfs read context in case we need to do the actual netfs
412 * read because we've encountered a cache read failure */
413 fscache_get_context(object->cookie, op->context);
414
415 /* we wait for the operation to become active, and then process it
416 * *here*, in this thread, and not in the thread pool */
David Howells60d543c2009-11-19 18:11:45 +0000417 ret = fscache_wait_for_retrieval_activation(
418 object, op,
419 __fscache_stat(&fscache_n_retrieval_op_waits),
420 __fscache_stat(&fscache_n_retrievals_object_dead));
421 if (ret < 0)
422 goto error;
David Howellsb5108822009-04-03 16:42:39 +0100423
424 /* ask the cache to honour the operation */
425 if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) {
David Howells52bd75f2009-11-19 18:11:08 +0000426 fscache_stat(&fscache_n_cop_allocate_page);
David Howellsb5108822009-04-03 16:42:39 +0100427 ret = object->cache->ops->allocate_page(op, page, gfp);
David Howells52bd75f2009-11-19 18:11:08 +0000428 fscache_stat_d(&fscache_n_cop_allocate_page);
David Howellsb5108822009-04-03 16:42:39 +0100429 if (ret == 0)
430 ret = -ENODATA;
431 } else {
David Howells52bd75f2009-11-19 18:11:08 +0000432 fscache_stat(&fscache_n_cop_read_or_alloc_page);
David Howellsb5108822009-04-03 16:42:39 +0100433 ret = object->cache->ops->read_or_alloc_page(op, page, gfp);
David Howells52bd75f2009-11-19 18:11:08 +0000434 fscache_stat_d(&fscache_n_cop_read_or_alloc_page);
David Howellsb5108822009-04-03 16:42:39 +0100435 }
436
David Howells5753c442009-11-19 18:11:19 +0000437error:
David Howellsb5108822009-04-03 16:42:39 +0100438 if (ret == -ENOMEM)
439 fscache_stat(&fscache_n_retrievals_nomem);
440 else if (ret == -ERESTARTSYS)
441 fscache_stat(&fscache_n_retrievals_intr);
442 else if (ret == -ENODATA)
443 fscache_stat(&fscache_n_retrievals_nodata);
444 else if (ret < 0)
445 fscache_stat(&fscache_n_retrievals_nobufs);
446 else
447 fscache_stat(&fscache_n_retrievals_ok);
448
449 fscache_put_retrieval(op);
450 _leave(" = %d", ret);
451 return ret;
452
453nobufs_unlock:
454 spin_unlock(&cookie->lock);
455 kfree(op);
456nobufs:
457 fscache_stat(&fscache_n_retrievals_nobufs);
458 _leave(" = -ENOBUFS");
459 return -ENOBUFS;
460}
461EXPORT_SYMBOL(__fscache_read_or_alloc_page);
462
463/*
464 * read a list of page from the cache or allocate a block in which to store
465 * them
466 * - we return:
467 * -ENOMEM - out of memory, some pages may be being read
468 * -ERESTARTSYS - interrupted, some pages may be being read
469 * -ENOBUFS - no backing object or space available in which to cache any
470 * pages not being read
471 * -ENODATA - no data available in the backing object for some or all of
472 * the pages
473 * 0 - dispatched a read on all pages
474 *
475 * end_io_func() will be called for each page read from the cache as it is
476 * finishes being read
477 *
478 * any pages for which a read is dispatched will be removed from pages and
479 * nr_pages
480 */
481int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
482 struct address_space *mapping,
483 struct list_head *pages,
484 unsigned *nr_pages,
485 fscache_rw_complete_t end_io_func,
486 void *context,
487 gfp_t gfp)
488{
David Howellsb5108822009-04-03 16:42:39 +0100489 struct fscache_retrieval *op;
490 struct fscache_object *object;
491 int ret;
492
493 _enter("%p,,%d,,,", cookie, *nr_pages);
494
495 fscache_stat(&fscache_n_retrievals);
496
497 if (hlist_empty(&cookie->backing_objects))
498 goto nobufs;
499
500 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
501 ASSERTCMP(*nr_pages, >, 0);
502 ASSERT(!list_empty(pages));
503
504 if (fscache_wait_for_deferred_lookup(cookie) < 0)
505 return -ERESTARTSYS;
506
507 op = fscache_alloc_retrieval(mapping, end_io_func, context);
508 if (!op)
509 return -ENOMEM;
David Howells440f0af2009-11-19 18:11:01 +0000510 fscache_set_op_name(&op->op, "RetrRAN");
David Howellsb5108822009-04-03 16:42:39 +0100511
512 spin_lock(&cookie->lock);
513
514 if (hlist_empty(&cookie->backing_objects))
515 goto nobufs_unlock;
516 object = hlist_entry(cookie->backing_objects.first,
517 struct fscache_object, cookie_link);
518
David Howells4fbf4292009-11-19 18:11:04 +0000519 atomic_inc(&object->n_reads);
520 set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
521
David Howellsb5108822009-04-03 16:42:39 +0100522 if (fscache_submit_op(object, &op->op) < 0)
523 goto nobufs_unlock;
524 spin_unlock(&cookie->lock);
525
526 fscache_stat(&fscache_n_retrieval_ops);
527
528 /* pin the netfs read context in case we need to do the actual netfs
529 * read because we've encountered a cache read failure */
530 fscache_get_context(object->cookie, op->context);
531
532 /* we wait for the operation to become active, and then process it
533 * *here*, in this thread, and not in the thread pool */
David Howells60d543c2009-11-19 18:11:45 +0000534 ret = fscache_wait_for_retrieval_activation(
535 object, op,
536 __fscache_stat(&fscache_n_retrieval_op_waits),
537 __fscache_stat(&fscache_n_retrievals_object_dead));
538 if (ret < 0)
539 goto error;
David Howellsb5108822009-04-03 16:42:39 +0100540
541 /* ask the cache to honour the operation */
David Howells52bd75f2009-11-19 18:11:08 +0000542 if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) {
543 fscache_stat(&fscache_n_cop_allocate_pages);
544 ret = object->cache->ops->allocate_pages(
545 op, pages, nr_pages, gfp);
546 fscache_stat_d(&fscache_n_cop_allocate_pages);
547 } else {
548 fscache_stat(&fscache_n_cop_read_or_alloc_pages);
549 ret = object->cache->ops->read_or_alloc_pages(
550 op, pages, nr_pages, gfp);
551 fscache_stat_d(&fscache_n_cop_read_or_alloc_pages);
552 }
David Howellsb5108822009-04-03 16:42:39 +0100553
David Howells5753c442009-11-19 18:11:19 +0000554error:
David Howellsb5108822009-04-03 16:42:39 +0100555 if (ret == -ENOMEM)
556 fscache_stat(&fscache_n_retrievals_nomem);
557 else if (ret == -ERESTARTSYS)
558 fscache_stat(&fscache_n_retrievals_intr);
559 else if (ret == -ENODATA)
560 fscache_stat(&fscache_n_retrievals_nodata);
561 else if (ret < 0)
562 fscache_stat(&fscache_n_retrievals_nobufs);
563 else
564 fscache_stat(&fscache_n_retrievals_ok);
565
566 fscache_put_retrieval(op);
567 _leave(" = %d", ret);
568 return ret;
569
570nobufs_unlock:
571 spin_unlock(&cookie->lock);
572 kfree(op);
573nobufs:
574 fscache_stat(&fscache_n_retrievals_nobufs);
575 _leave(" = -ENOBUFS");
576 return -ENOBUFS;
577}
578EXPORT_SYMBOL(__fscache_read_or_alloc_pages);
579
580/*
581 * allocate a block in the cache on which to store a page
582 * - we return:
583 * -ENOMEM - out of memory, nothing done
584 * -ERESTARTSYS - interrupted
585 * -ENOBUFS - no backing object available in which to cache the block
586 * 0 - block allocated
587 */
588int __fscache_alloc_page(struct fscache_cookie *cookie,
589 struct page *page,
590 gfp_t gfp)
591{
592 struct fscache_retrieval *op;
593 struct fscache_object *object;
594 int ret;
595
596 _enter("%p,%p,,,", cookie, page);
597
598 fscache_stat(&fscache_n_allocs);
599
600 if (hlist_empty(&cookie->backing_objects))
601 goto nobufs;
602
603 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
604 ASSERTCMP(page, !=, NULL);
605
606 if (fscache_wait_for_deferred_lookup(cookie) < 0)
607 return -ERESTARTSYS;
608
609 op = fscache_alloc_retrieval(page->mapping, NULL, NULL);
610 if (!op)
611 return -ENOMEM;
David Howells440f0af2009-11-19 18:11:01 +0000612 fscache_set_op_name(&op->op, "RetrAL1");
David Howellsb5108822009-04-03 16:42:39 +0100613
614 spin_lock(&cookie->lock);
615
616 if (hlist_empty(&cookie->backing_objects))
617 goto nobufs_unlock;
618 object = hlist_entry(cookie->backing_objects.first,
619 struct fscache_object, cookie_link);
620
621 if (fscache_submit_op(object, &op->op) < 0)
622 goto nobufs_unlock;
623 spin_unlock(&cookie->lock);
624
625 fscache_stat(&fscache_n_alloc_ops);
626
David Howells60d543c2009-11-19 18:11:45 +0000627 ret = fscache_wait_for_retrieval_activation(
628 object, op,
629 __fscache_stat(&fscache_n_alloc_op_waits),
630 __fscache_stat(&fscache_n_allocs_object_dead));
631 if (ret < 0)
632 goto error;
David Howellsb5108822009-04-03 16:42:39 +0100633
634 /* ask the cache to honour the operation */
David Howells52bd75f2009-11-19 18:11:08 +0000635 fscache_stat(&fscache_n_cop_allocate_page);
David Howellsb5108822009-04-03 16:42:39 +0100636 ret = object->cache->ops->allocate_page(op, page, gfp);
David Howells52bd75f2009-11-19 18:11:08 +0000637 fscache_stat_d(&fscache_n_cop_allocate_page);
David Howellsb5108822009-04-03 16:42:39 +0100638
David Howells5753c442009-11-19 18:11:19 +0000639error:
640 if (ret == -ERESTARTSYS)
641 fscache_stat(&fscache_n_allocs_intr);
642 else if (ret < 0)
David Howellsb5108822009-04-03 16:42:39 +0100643 fscache_stat(&fscache_n_allocs_nobufs);
644 else
645 fscache_stat(&fscache_n_allocs_ok);
646
647 fscache_put_retrieval(op);
648 _leave(" = %d", ret);
649 return ret;
650
651nobufs_unlock:
652 spin_unlock(&cookie->lock);
653 kfree(op);
654nobufs:
655 fscache_stat(&fscache_n_allocs_nobufs);
656 _leave(" = -ENOBUFS");
657 return -ENOBUFS;
658}
659EXPORT_SYMBOL(__fscache_alloc_page);
660
661/*
662 * release a write op reference
663 */
664static void fscache_release_write_op(struct fscache_operation *_op)
665{
666 _enter("{OP%x}", _op->debug_id);
667}
668
669/*
670 * perform the background storage of a page into the cache
671 */
672static void fscache_write_op(struct fscache_operation *_op)
673{
674 struct fscache_storage *op =
675 container_of(_op, struct fscache_storage, op);
676 struct fscache_object *object = op->op.object;
David Howells1bccf512009-11-19 18:11:25 +0000677 struct fscache_cookie *cookie;
David Howellsb5108822009-04-03 16:42:39 +0100678 struct page *page;
679 unsigned n;
680 void *results[1];
681 int ret;
682
683 _enter("{OP%x,%d}", op->op.debug_id, atomic_read(&op->op.usage));
684
David Howells440f0af2009-11-19 18:11:01 +0000685 fscache_set_op_state(&op->op, "GetPage");
686
David Howellsb5108822009-04-03 16:42:39 +0100687 spin_lock(&object->lock);
David Howells1bccf512009-11-19 18:11:25 +0000688 cookie = object->cookie;
David Howellsb5108822009-04-03 16:42:39 +0100689
David Howells1bccf512009-11-19 18:11:25 +0000690 if (!fscache_object_is_active(object) || !cookie) {
David Howellsb5108822009-04-03 16:42:39 +0100691 spin_unlock(&object->lock);
David Howellsb5108822009-04-03 16:42:39 +0100692 _leave("");
693 return;
694 }
695
David Howells1bccf512009-11-19 18:11:25 +0000696 spin_lock(&cookie->stores_lock);
697
David Howellsb5108822009-04-03 16:42:39 +0100698 fscache_stat(&fscache_n_store_calls);
699
700 /* find a page to store */
701 page = NULL;
702 n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0, 1,
703 FSCACHE_COOKIE_PENDING_TAG);
704 if (n != 1)
705 goto superseded;
706 page = results[0];
707 _debug("gang %d [%lx]", n, page->index);
David Howells1bccf512009-11-19 18:11:25 +0000708 if (page->index > op->store_limit) {
709 fscache_stat(&fscache_n_store_pages_over_limit);
David Howellsb5108822009-04-03 16:42:39 +0100710 goto superseded;
David Howells1bccf512009-11-19 18:11:25 +0000711 }
David Howellsb5108822009-04-03 16:42:39 +0100712
Dan Carpenter08a66852010-06-01 20:58:22 +0100713 radix_tree_tag_set(&cookie->stores, page->index,
714 FSCACHE_COOKIE_STORING_TAG);
715 radix_tree_tag_clear(&cookie->stores, page->index,
716 FSCACHE_COOKIE_PENDING_TAG);
David Howellsb5108822009-04-03 16:42:39 +0100717
David Howells1bccf512009-11-19 18:11:25 +0000718 spin_unlock(&cookie->stores_lock);
David Howellsb5108822009-04-03 16:42:39 +0100719 spin_unlock(&object->lock);
David Howellsb5108822009-04-03 16:42:39 +0100720
Dan Carpenter08a66852010-06-01 20:58:22 +0100721 fscache_set_op_state(&op->op, "Store");
722 fscache_stat(&fscache_n_store_pages);
723 fscache_stat(&fscache_n_cop_write_page);
724 ret = object->cache->ops->write_page(op, page);
725 fscache_stat_d(&fscache_n_cop_write_page);
726 fscache_set_op_state(&op->op, "EndWrite");
727 fscache_end_page_write(object, page);
728 if (ret < 0) {
729 fscache_set_op_state(&op->op, "Abort");
730 fscache_abort_object(object);
731 } else {
732 fscache_enqueue_operation(&op->op);
David Howellsb5108822009-04-03 16:42:39 +0100733 }
734
735 _leave("");
736 return;
737
738superseded:
739 /* this writer is going away and there aren't any more things to
740 * write */
741 _debug("cease");
David Howells1bccf512009-11-19 18:11:25 +0000742 spin_unlock(&cookie->stores_lock);
David Howellsb5108822009-04-03 16:42:39 +0100743 clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
744 spin_unlock(&object->lock);
David Howellsb5108822009-04-03 16:42:39 +0100745 _leave("");
746}
747
748/*
749 * request a page be stored in the cache
750 * - returns:
751 * -ENOMEM - out of memory, nothing done
752 * -ENOBUFS - no backing object available in which to cache the page
753 * 0 - dispatched a write - it'll call end_io_func() when finished
754 *
755 * if the cookie still has a backing object at this point, that object can be
756 * in one of a few states with respect to storage processing:
757 *
758 * (1) negative lookup, object not yet created (FSCACHE_COOKIE_CREATING is
759 * set)
760 *
761 * (a) no writes yet (set FSCACHE_COOKIE_PENDING_FILL and queue deferred
762 * fill op)
763 *
764 * (b) writes deferred till post-creation (mark page for writing and
765 * return immediately)
766 *
767 * (2) negative lookup, object created, initial fill being made from netfs
768 * (FSCACHE_COOKIE_INITIAL_FILL is set)
769 *
770 * (a) fill point not yet reached this page (mark page for writing and
771 * return)
772 *
773 * (b) fill point passed this page (queue op to store this page)
774 *
775 * (3) object extant (queue op to store this page)
776 *
777 * any other state is invalid
778 */
779int __fscache_write_page(struct fscache_cookie *cookie,
780 struct page *page,
781 gfp_t gfp)
782{
783 struct fscache_storage *op;
784 struct fscache_object *object;
785 int ret;
786
787 _enter("%p,%x,", cookie, (u32) page->flags);
788
789 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
790 ASSERT(PageFsCache(page));
791
792 fscache_stat(&fscache_n_stores);
793
794 op = kzalloc(sizeof(*op), GFP_NOIO);
795 if (!op)
796 goto nomem;
797
798 fscache_operation_init(&op->op, fscache_release_write_op);
799 fscache_operation_init_slow(&op->op, fscache_write_op);
800 op->op.flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_WAITING);
David Howells440f0af2009-11-19 18:11:01 +0000801 fscache_set_op_name(&op->op, "Write1");
David Howellsb5108822009-04-03 16:42:39 +0100802
803 ret = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
804 if (ret < 0)
805 goto nomem_free;
806
807 ret = -ENOBUFS;
808 spin_lock(&cookie->lock);
809
810 if (hlist_empty(&cookie->backing_objects))
811 goto nobufs;
812 object = hlist_entry(cookie->backing_objects.first,
813 struct fscache_object, cookie_link);
814 if (test_bit(FSCACHE_IOERROR, &object->cache->flags))
815 goto nobufs;
816
817 /* add the page to the pending-storage radix tree on the backing
818 * object */
819 spin_lock(&object->lock);
David Howells1bccf512009-11-19 18:11:25 +0000820 spin_lock(&cookie->stores_lock);
David Howellsb5108822009-04-03 16:42:39 +0100821
822 _debug("store limit %llx", (unsigned long long) object->store_limit);
823
824 ret = radix_tree_insert(&cookie->stores, page->index, page);
825 if (ret < 0) {
826 if (ret == -EEXIST)
827 goto already_queued;
828 _debug("insert failed %d", ret);
829 goto nobufs_unlock_obj;
830 }
831
832 radix_tree_tag_set(&cookie->stores, page->index,
833 FSCACHE_COOKIE_PENDING_TAG);
834 page_cache_get(page);
835
836 /* we only want one writer at a time, but we do need to queue new
837 * writers after exclusive ops */
838 if (test_and_set_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags))
839 goto already_pending;
840
David Howells1bccf512009-11-19 18:11:25 +0000841 spin_unlock(&cookie->stores_lock);
David Howellsb5108822009-04-03 16:42:39 +0100842 spin_unlock(&object->lock);
843
844 op->op.debug_id = atomic_inc_return(&fscache_op_debug_id);
845 op->store_limit = object->store_limit;
846
847 if (fscache_submit_op(object, &op->op) < 0)
848 goto submit_failed;
849
850 spin_unlock(&cookie->lock);
851 radix_tree_preload_end();
852 fscache_stat(&fscache_n_store_ops);
853 fscache_stat(&fscache_n_stores_ok);
854
855 /* the slow work queue now carries its own ref on the object */
856 fscache_put_operation(&op->op);
857 _leave(" = 0");
858 return 0;
859
860already_queued:
861 fscache_stat(&fscache_n_stores_again);
862already_pending:
David Howells1bccf512009-11-19 18:11:25 +0000863 spin_unlock(&cookie->stores_lock);
David Howellsb5108822009-04-03 16:42:39 +0100864 spin_unlock(&object->lock);
865 spin_unlock(&cookie->lock);
866 radix_tree_preload_end();
867 kfree(op);
868 fscache_stat(&fscache_n_stores_ok);
869 _leave(" = 0");
870 return 0;
871
872submit_failed:
David Howells1bccf512009-11-19 18:11:25 +0000873 spin_lock(&cookie->stores_lock);
David Howellsb5108822009-04-03 16:42:39 +0100874 radix_tree_delete(&cookie->stores, page->index);
David Howells1bccf512009-11-19 18:11:25 +0000875 spin_unlock(&cookie->stores_lock);
David Howellsb5108822009-04-03 16:42:39 +0100876 page_cache_release(page);
877 ret = -ENOBUFS;
878 goto nobufs;
879
880nobufs_unlock_obj:
Dan Carpenter1147d0f2010-03-23 14:48:37 +0000881 spin_unlock(&cookie->stores_lock);
David Howellsb5108822009-04-03 16:42:39 +0100882 spin_unlock(&object->lock);
883nobufs:
884 spin_unlock(&cookie->lock);
885 radix_tree_preload_end();
886 kfree(op);
887 fscache_stat(&fscache_n_stores_nobufs);
888 _leave(" = -ENOBUFS");
889 return -ENOBUFS;
890
891nomem_free:
892 kfree(op);
893nomem:
894 fscache_stat(&fscache_n_stores_oom);
895 _leave(" = -ENOMEM");
896 return -ENOMEM;
897}
898EXPORT_SYMBOL(__fscache_write_page);
899
900/*
901 * remove a page from the cache
902 */
903void __fscache_uncache_page(struct fscache_cookie *cookie, struct page *page)
904{
905 struct fscache_object *object;
906
907 _enter(",%p", page);
908
909 ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
910 ASSERTCMP(page, !=, NULL);
911
912 fscache_stat(&fscache_n_uncaches);
913
914 /* cache withdrawal may beat us to it */
915 if (!PageFsCache(page))
916 goto done;
917
918 /* get the object */
919 spin_lock(&cookie->lock);
920
921 if (hlist_empty(&cookie->backing_objects)) {
922 ClearPageFsCache(page);
923 goto done_unlock;
924 }
925
926 object = hlist_entry(cookie->backing_objects.first,
927 struct fscache_object, cookie_link);
928
929 /* there might now be stuff on disk we could read */
930 clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
931
932 /* only invoke the cache backend if we managed to mark the page
933 * uncached here; this deals with synchronisation vs withdrawal */
934 if (TestClearPageFsCache(page) &&
935 object->cache->ops->uncache_page) {
936 /* the cache backend releases the cookie lock */
David Howells52bd75f2009-11-19 18:11:08 +0000937 fscache_stat(&fscache_n_cop_uncache_page);
David Howellsb5108822009-04-03 16:42:39 +0100938 object->cache->ops->uncache_page(object, page);
David Howells52bd75f2009-11-19 18:11:08 +0000939 fscache_stat_d(&fscache_n_cop_uncache_page);
David Howellsb5108822009-04-03 16:42:39 +0100940 goto done;
941 }
942
943done_unlock:
944 spin_unlock(&cookie->lock);
945done:
946 _leave("");
947}
948EXPORT_SYMBOL(__fscache_uncache_page);
949
950/**
951 * fscache_mark_pages_cached - Mark pages as being cached
952 * @op: The retrieval op pages are being marked for
953 * @pagevec: The pages to be marked
954 *
955 * Mark a bunch of netfs pages as being cached. After this is called,
956 * the netfs must call fscache_uncache_page() to remove the mark.
957 */
958void fscache_mark_pages_cached(struct fscache_retrieval *op,
959 struct pagevec *pagevec)
960{
961 struct fscache_cookie *cookie = op->op.object->cookie;
962 unsigned long loop;
963
964#ifdef CONFIG_FSCACHE_STATS
965 atomic_add(pagevec->nr, &fscache_n_marks);
966#endif
967
968 for (loop = 0; loop < pagevec->nr; loop++) {
969 struct page *page = pagevec->pages[loop];
970
971 _debug("- mark %p{%lx}", page, page->index);
972 if (TestSetPageFsCache(page)) {
973 static bool once_only;
974 if (!once_only) {
975 once_only = true;
976 printk(KERN_WARNING "FS-Cache:"
977 " Cookie type %s marked page %lx"
978 " multiple times\n",
979 cookie->def->name, page->index);
980 }
981 }
982 }
983
984 if (cookie->def->mark_pages_cached)
985 cookie->def->mark_pages_cached(cookie->netfs_data,
986 op->mapping, pagevec);
987 pagevec_reinit(pagevec);
988}
989EXPORT_SYMBOL(fscache_mark_pages_cached);