FS-Cache: Annotate slow-work runqueue proc lines for FS-Cache work items
[linux-2.6.git] / fs / fscache / page.c
1 /* Cache page management and data I/O routines
2  *
3  * Copyright (C) 2004-2008 Red Hat, Inc. All Rights Reserved.
4  * Written by David Howells (dhowells@redhat.com)
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * as published by the Free Software Foundation; either version
9  * 2 of the License, or (at your option) any later version.
10  */
11
12 #define FSCACHE_DEBUG_LEVEL PAGE
13 #include <linux/module.h>
14 #include <linux/fscache-cache.h>
15 #include <linux/buffer_head.h>
16 #include <linux/pagevec.h>
17 #include "internal.h"
18
19 /*
20  * check to see if a page is being written to the cache
21  */
22 bool __fscache_check_page_write(struct fscache_cookie *cookie, struct page *page)
23 {
24         void *val;
25
26         rcu_read_lock();
27         val = radix_tree_lookup(&cookie->stores, page->index);
28         rcu_read_unlock();
29
30         return val != NULL;
31 }
32 EXPORT_SYMBOL(__fscache_check_page_write);
33
34 /*
35  * wait for a page to finish being written to the cache
36  */
37 void __fscache_wait_on_page_write(struct fscache_cookie *cookie, struct page *page)
38 {
39         wait_queue_head_t *wq = bit_waitqueue(&cookie->flags, 0);
40
41         wait_event(*wq, !__fscache_check_page_write(cookie, page));
42 }
43 EXPORT_SYMBOL(__fscache_wait_on_page_write);
44
45 /*
46  * note that a page has finished being written to the cache
47  */
48 static void fscache_end_page_write(struct fscache_cookie *cookie, struct page *page)
49 {
50         struct page *xpage;
51
52         spin_lock(&cookie->lock);
53         xpage = radix_tree_delete(&cookie->stores, page->index);
54         spin_unlock(&cookie->lock);
55         ASSERT(xpage != NULL);
56
57         wake_up_bit(&cookie->flags, 0);
58 }
59
60 /*
61  * actually apply the changed attributes to a cache object
62  */
63 static void fscache_attr_changed_op(struct fscache_operation *op)
64 {
65         struct fscache_object *object = op->object;
66         int ret;
67
68         _enter("{OBJ%x OP%x}", object->debug_id, op->debug_id);
69
70         fscache_stat(&fscache_n_attr_changed_calls);
71
72         if (fscache_object_is_active(object)) {
73                 fscache_set_op_state(op, "CallFS");
74                 ret = object->cache->ops->attr_changed(object);
75                 fscache_set_op_state(op, "Done");
76                 if (ret < 0)
77                         fscache_abort_object(object);
78         }
79
80         _leave("");
81 }
82
83 /*
84  * notification that the attributes on an object have changed
85  */
86 int __fscache_attr_changed(struct fscache_cookie *cookie)
87 {
88         struct fscache_operation *op;
89         struct fscache_object *object;
90
91         _enter("%p", cookie);
92
93         ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
94
95         fscache_stat(&fscache_n_attr_changed);
96
97         op = kzalloc(sizeof(*op), GFP_KERNEL);
98         if (!op) {
99                 fscache_stat(&fscache_n_attr_changed_nomem);
100                 _leave(" = -ENOMEM");
101                 return -ENOMEM;
102         }
103
104         fscache_operation_init(op, NULL);
105         fscache_operation_init_slow(op, fscache_attr_changed_op);
106         op->flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_EXCLUSIVE);
107         fscache_set_op_name(op, "Attr");
108
109         spin_lock(&cookie->lock);
110
111         if (hlist_empty(&cookie->backing_objects))
112                 goto nobufs;
113         object = hlist_entry(cookie->backing_objects.first,
114                              struct fscache_object, cookie_link);
115
116         if (fscache_submit_exclusive_op(object, op) < 0)
117                 goto nobufs;
118         spin_unlock(&cookie->lock);
119         fscache_stat(&fscache_n_attr_changed_ok);
120         fscache_put_operation(op);
121         _leave(" = 0");
122         return 0;
123
124 nobufs:
125         spin_unlock(&cookie->lock);
126         kfree(op);
127         fscache_stat(&fscache_n_attr_changed_nobufs);
128         _leave(" = %d", -ENOBUFS);
129         return -ENOBUFS;
130 }
131 EXPORT_SYMBOL(__fscache_attr_changed);
132
133 /*
134  * handle secondary execution given to a retrieval op on behalf of the
135  * cache
136  */
137 static void fscache_retrieval_work(struct work_struct *work)
138 {
139         struct fscache_retrieval *op =
140                 container_of(work, struct fscache_retrieval, op.fast_work);
141         unsigned long start;
142
143         _enter("{OP%x}", op->op.debug_id);
144
145         start = jiffies;
146         op->op.processor(&op->op);
147         fscache_hist(fscache_ops_histogram, start);
148         fscache_put_operation(&op->op);
149 }
150
151 /*
152  * release a retrieval op reference
153  */
154 static void fscache_release_retrieval_op(struct fscache_operation *_op)
155 {
156         struct fscache_retrieval *op =
157                 container_of(_op, struct fscache_retrieval, op);
158
159         _enter("{OP%x}", op->op.debug_id);
160
161         fscache_hist(fscache_retrieval_histogram, op->start_time);
162         if (op->context)
163                 fscache_put_context(op->op.object->cookie, op->context);
164
165         _leave("");
166 }
167
168 /*
169  * allocate a retrieval op
170  */
171 static struct fscache_retrieval *fscache_alloc_retrieval(
172         struct address_space *mapping,
173         fscache_rw_complete_t end_io_func,
174         void *context)
175 {
176         struct fscache_retrieval *op;
177
178         /* allocate a retrieval operation and attempt to submit it */
179         op = kzalloc(sizeof(*op), GFP_NOIO);
180         if (!op) {
181                 fscache_stat(&fscache_n_retrievals_nomem);
182                 return NULL;
183         }
184
185         fscache_operation_init(&op->op, fscache_release_retrieval_op);
186         op->op.flags    = FSCACHE_OP_MYTHREAD | (1 << FSCACHE_OP_WAITING);
187         op->mapping     = mapping;
188         op->end_io_func = end_io_func;
189         op->context     = context;
190         op->start_time  = jiffies;
191         INIT_WORK(&op->op.fast_work, fscache_retrieval_work);
192         INIT_LIST_HEAD(&op->to_do);
193         fscache_set_op_name(&op->op, "Retr");
194         return op;
195 }
196
197 /*
198  * wait for a deferred lookup to complete
199  */
200 static int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie)
201 {
202         unsigned long jif;
203
204         _enter("");
205
206         if (!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)) {
207                 _leave(" = 0 [imm]");
208                 return 0;
209         }
210
211         fscache_stat(&fscache_n_retrievals_wait);
212
213         jif = jiffies;
214         if (wait_on_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP,
215                         fscache_wait_bit_interruptible,
216                         TASK_INTERRUPTIBLE) != 0) {
217                 fscache_stat(&fscache_n_retrievals_intr);
218                 _leave(" = -ERESTARTSYS");
219                 return -ERESTARTSYS;
220         }
221
222         ASSERT(!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags));
223
224         smp_rmb();
225         fscache_hist(fscache_retrieval_delay_histogram, jif);
226         _leave(" = 0 [dly]");
227         return 0;
228 }
229
230 /*
231  * read a page from the cache or allocate a block in which to store it
232  * - we return:
233  *   -ENOMEM    - out of memory, nothing done
234  *   -ERESTARTSYS - interrupted
235  *   -ENOBUFS   - no backing object available in which to cache the block
236  *   -ENODATA   - no data available in the backing object for this block
237  *   0          - dispatched a read - it'll call end_io_func() when finished
238  */
239 int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
240                                  struct page *page,
241                                  fscache_rw_complete_t end_io_func,
242                                  void *context,
243                                  gfp_t gfp)
244 {
245         struct fscache_retrieval *op;
246         struct fscache_object *object;
247         int ret;
248
249         _enter("%p,%p,,,", cookie, page);
250
251         fscache_stat(&fscache_n_retrievals);
252
253         if (hlist_empty(&cookie->backing_objects))
254                 goto nobufs;
255
256         ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
257         ASSERTCMP(page, !=, NULL);
258
259         if (fscache_wait_for_deferred_lookup(cookie) < 0)
260                 return -ERESTARTSYS;
261
262         op = fscache_alloc_retrieval(page->mapping, end_io_func, context);
263         if (!op) {
264                 _leave(" = -ENOMEM");
265                 return -ENOMEM;
266         }
267         fscache_set_op_name(&op->op, "RetrRA1");
268
269         spin_lock(&cookie->lock);
270
271         if (hlist_empty(&cookie->backing_objects))
272                 goto nobufs_unlock;
273         object = hlist_entry(cookie->backing_objects.first,
274                              struct fscache_object, cookie_link);
275
276         ASSERTCMP(object->state, >, FSCACHE_OBJECT_LOOKING_UP);
277
278         if (fscache_submit_op(object, &op->op) < 0)
279                 goto nobufs_unlock;
280         spin_unlock(&cookie->lock);
281
282         fscache_stat(&fscache_n_retrieval_ops);
283
284         /* pin the netfs read context in case we need to do the actual netfs
285          * read because we've encountered a cache read failure */
286         fscache_get_context(object->cookie, op->context);
287
288         /* we wait for the operation to become active, and then process it
289          * *here*, in this thread, and not in the thread pool */
290         if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) {
291                 _debug(">>> WT");
292                 fscache_stat(&fscache_n_retrieval_op_waits);
293                 wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
294                             fscache_wait_bit, TASK_UNINTERRUPTIBLE);
295                 _debug("<<< GO");
296         }
297
298         /* ask the cache to honour the operation */
299         if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) {
300                 ret = object->cache->ops->allocate_page(op, page, gfp);
301                 if (ret == 0)
302                         ret = -ENODATA;
303         } else {
304                 ret = object->cache->ops->read_or_alloc_page(op, page, gfp);
305         }
306
307         if (ret == -ENOMEM)
308                 fscache_stat(&fscache_n_retrievals_nomem);
309         else if (ret == -ERESTARTSYS)
310                 fscache_stat(&fscache_n_retrievals_intr);
311         else if (ret == -ENODATA)
312                 fscache_stat(&fscache_n_retrievals_nodata);
313         else if (ret < 0)
314                 fscache_stat(&fscache_n_retrievals_nobufs);
315         else
316                 fscache_stat(&fscache_n_retrievals_ok);
317
318         fscache_put_retrieval(op);
319         _leave(" = %d", ret);
320         return ret;
321
322 nobufs_unlock:
323         spin_unlock(&cookie->lock);
324         kfree(op);
325 nobufs:
326         fscache_stat(&fscache_n_retrievals_nobufs);
327         _leave(" = -ENOBUFS");
328         return -ENOBUFS;
329 }
330 EXPORT_SYMBOL(__fscache_read_or_alloc_page);
331
332 /*
333  * read a list of page from the cache or allocate a block in which to store
334  * them
335  * - we return:
336  *   -ENOMEM    - out of memory, some pages may be being read
337  *   -ERESTARTSYS - interrupted, some pages may be being read
338  *   -ENOBUFS   - no backing object or space available in which to cache any
339  *                pages not being read
340  *   -ENODATA   - no data available in the backing object for some or all of
341  *                the pages
342  *   0          - dispatched a read on all pages
343  *
344  * end_io_func() will be called for each page read from the cache as it is
345  * finishes being read
346  *
347  * any pages for which a read is dispatched will be removed from pages and
348  * nr_pages
349  */
350 int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
351                                   struct address_space *mapping,
352                                   struct list_head *pages,
353                                   unsigned *nr_pages,
354                                   fscache_rw_complete_t end_io_func,
355                                   void *context,
356                                   gfp_t gfp)
357 {
358         fscache_pages_retrieval_func_t func;
359         struct fscache_retrieval *op;
360         struct fscache_object *object;
361         int ret;
362
363         _enter("%p,,%d,,,", cookie, *nr_pages);
364
365         fscache_stat(&fscache_n_retrievals);
366
367         if (hlist_empty(&cookie->backing_objects))
368                 goto nobufs;
369
370         ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
371         ASSERTCMP(*nr_pages, >, 0);
372         ASSERT(!list_empty(pages));
373
374         if (fscache_wait_for_deferred_lookup(cookie) < 0)
375                 return -ERESTARTSYS;
376
377         op = fscache_alloc_retrieval(mapping, end_io_func, context);
378         if (!op)
379                 return -ENOMEM;
380         fscache_set_op_name(&op->op, "RetrRAN");
381
382         spin_lock(&cookie->lock);
383
384         if (hlist_empty(&cookie->backing_objects))
385                 goto nobufs_unlock;
386         object = hlist_entry(cookie->backing_objects.first,
387                              struct fscache_object, cookie_link);
388
389         if (fscache_submit_op(object, &op->op) < 0)
390                 goto nobufs_unlock;
391         spin_unlock(&cookie->lock);
392
393         fscache_stat(&fscache_n_retrieval_ops);
394
395         /* pin the netfs read context in case we need to do the actual netfs
396          * read because we've encountered a cache read failure */
397         fscache_get_context(object->cookie, op->context);
398
399         /* we wait for the operation to become active, and then process it
400          * *here*, in this thread, and not in the thread pool */
401         if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) {
402                 _debug(">>> WT");
403                 fscache_stat(&fscache_n_retrieval_op_waits);
404                 wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
405                             fscache_wait_bit, TASK_UNINTERRUPTIBLE);
406                 _debug("<<< GO");
407         }
408
409         /* ask the cache to honour the operation */
410         if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags))
411                 func = object->cache->ops->allocate_pages;
412         else
413                 func = object->cache->ops->read_or_alloc_pages;
414         ret = func(op, pages, nr_pages, gfp);
415
416         if (ret == -ENOMEM)
417                 fscache_stat(&fscache_n_retrievals_nomem);
418         else if (ret == -ERESTARTSYS)
419                 fscache_stat(&fscache_n_retrievals_intr);
420         else if (ret == -ENODATA)
421                 fscache_stat(&fscache_n_retrievals_nodata);
422         else if (ret < 0)
423                 fscache_stat(&fscache_n_retrievals_nobufs);
424         else
425                 fscache_stat(&fscache_n_retrievals_ok);
426
427         fscache_put_retrieval(op);
428         _leave(" = %d", ret);
429         return ret;
430
431 nobufs_unlock:
432         spin_unlock(&cookie->lock);
433         kfree(op);
434 nobufs:
435         fscache_stat(&fscache_n_retrievals_nobufs);
436         _leave(" = -ENOBUFS");
437         return -ENOBUFS;
438 }
439 EXPORT_SYMBOL(__fscache_read_or_alloc_pages);
440
441 /*
442  * allocate a block in the cache on which to store a page
443  * - we return:
444  *   -ENOMEM    - out of memory, nothing done
445  *   -ERESTARTSYS - interrupted
446  *   -ENOBUFS   - no backing object available in which to cache the block
447  *   0          - block allocated
448  */
449 int __fscache_alloc_page(struct fscache_cookie *cookie,
450                          struct page *page,
451                          gfp_t gfp)
452 {
453         struct fscache_retrieval *op;
454         struct fscache_object *object;
455         int ret;
456
457         _enter("%p,%p,,,", cookie, page);
458
459         fscache_stat(&fscache_n_allocs);
460
461         if (hlist_empty(&cookie->backing_objects))
462                 goto nobufs;
463
464         ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
465         ASSERTCMP(page, !=, NULL);
466
467         if (fscache_wait_for_deferred_lookup(cookie) < 0)
468                 return -ERESTARTSYS;
469
470         op = fscache_alloc_retrieval(page->mapping, NULL, NULL);
471         if (!op)
472                 return -ENOMEM;
473         fscache_set_op_name(&op->op, "RetrAL1");
474
475         spin_lock(&cookie->lock);
476
477         if (hlist_empty(&cookie->backing_objects))
478                 goto nobufs_unlock;
479         object = hlist_entry(cookie->backing_objects.first,
480                              struct fscache_object, cookie_link);
481
482         if (fscache_submit_op(object, &op->op) < 0)
483                 goto nobufs_unlock;
484         spin_unlock(&cookie->lock);
485
486         fscache_stat(&fscache_n_alloc_ops);
487
488         if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) {
489                 _debug(">>> WT");
490                 fscache_stat(&fscache_n_alloc_op_waits);
491                 wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
492                             fscache_wait_bit, TASK_UNINTERRUPTIBLE);
493                 _debug("<<< GO");
494         }
495
496         /* ask the cache to honour the operation */
497         ret = object->cache->ops->allocate_page(op, page, gfp);
498
499         if (ret < 0)
500                 fscache_stat(&fscache_n_allocs_nobufs);
501         else
502                 fscache_stat(&fscache_n_allocs_ok);
503
504         fscache_put_retrieval(op);
505         _leave(" = %d", ret);
506         return ret;
507
508 nobufs_unlock:
509         spin_unlock(&cookie->lock);
510         kfree(op);
511 nobufs:
512         fscache_stat(&fscache_n_allocs_nobufs);
513         _leave(" = -ENOBUFS");
514         return -ENOBUFS;
515 }
516 EXPORT_SYMBOL(__fscache_alloc_page);
517
518 /*
519  * release a write op reference
520  */
521 static void fscache_release_write_op(struct fscache_operation *_op)
522 {
523         _enter("{OP%x}", _op->debug_id);
524 }
525
526 /*
527  * perform the background storage of a page into the cache
528  */
529 static void fscache_write_op(struct fscache_operation *_op)
530 {
531         struct fscache_storage *op =
532                 container_of(_op, struct fscache_storage, op);
533         struct fscache_object *object = op->op.object;
534         struct fscache_cookie *cookie = object->cookie;
535         struct page *page;
536         unsigned n;
537         void *results[1];
538         int ret;
539
540         _enter("{OP%x,%d}", op->op.debug_id, atomic_read(&op->op.usage));
541
542         fscache_set_op_state(&op->op, "GetPage");
543
544         spin_lock(&cookie->lock);
545         spin_lock(&object->lock);
546
547         if (!fscache_object_is_active(object)) {
548                 spin_unlock(&object->lock);
549                 spin_unlock(&cookie->lock);
550                 _leave("");
551                 return;
552         }
553
554         fscache_stat(&fscache_n_store_calls);
555
556         /* find a page to store */
557         page = NULL;
558         n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0, 1,
559                                        FSCACHE_COOKIE_PENDING_TAG);
560         if (n != 1)
561                 goto superseded;
562         page = results[0];
563         _debug("gang %d [%lx]", n, page->index);
564         if (page->index > op->store_limit)
565                 goto superseded;
566
567         radix_tree_tag_clear(&cookie->stores, page->index,
568                              FSCACHE_COOKIE_PENDING_TAG);
569
570         spin_unlock(&object->lock);
571         spin_unlock(&cookie->lock);
572
573         if (page) {
574                 fscache_set_op_state(&op->op, "Store");
575                 ret = object->cache->ops->write_page(op, page);
576                 fscache_set_op_state(&op->op, "EndWrite");
577                 fscache_end_page_write(cookie, page);
578                 page_cache_release(page);
579                 if (ret < 0) {
580                         fscache_set_op_state(&op->op, "Abort");
581                         fscache_abort_object(object);
582                 } else {
583                         fscache_enqueue_operation(&op->op);
584                 }
585         }
586
587         _leave("");
588         return;
589
590 superseded:
591         /* this writer is going away and there aren't any more things to
592          * write */
593         _debug("cease");
594         clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
595         spin_unlock(&object->lock);
596         spin_unlock(&cookie->lock);
597         _leave("");
598 }
599
600 /*
601  * request a page be stored in the cache
602  * - returns:
603  *   -ENOMEM    - out of memory, nothing done
604  *   -ENOBUFS   - no backing object available in which to cache the page
605  *   0          - dispatched a write - it'll call end_io_func() when finished
606  *
607  * if the cookie still has a backing object at this point, that object can be
608  * in one of a few states with respect to storage processing:
609  *
610  *  (1) negative lookup, object not yet created (FSCACHE_COOKIE_CREATING is
611  *      set)
612  *
613  *      (a) no writes yet (set FSCACHE_COOKIE_PENDING_FILL and queue deferred
614  *          fill op)
615  *
616  *      (b) writes deferred till post-creation (mark page for writing and
617  *          return immediately)
618  *
619  *  (2) negative lookup, object created, initial fill being made from netfs
620  *      (FSCACHE_COOKIE_INITIAL_FILL is set)
621  *
622  *      (a) fill point not yet reached this page (mark page for writing and
623  *          return)
624  *
625  *      (b) fill point passed this page (queue op to store this page)
626  *
627  *  (3) object extant (queue op to store this page)
628  *
629  * any other state is invalid
630  */
631 int __fscache_write_page(struct fscache_cookie *cookie,
632                          struct page *page,
633                          gfp_t gfp)
634 {
635         struct fscache_storage *op;
636         struct fscache_object *object;
637         int ret;
638
639         _enter("%p,%x,", cookie, (u32) page->flags);
640
641         ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
642         ASSERT(PageFsCache(page));
643
644         fscache_stat(&fscache_n_stores);
645
646         op = kzalloc(sizeof(*op), GFP_NOIO);
647         if (!op)
648                 goto nomem;
649
650         fscache_operation_init(&op->op, fscache_release_write_op);
651         fscache_operation_init_slow(&op->op, fscache_write_op);
652         op->op.flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_WAITING);
653         fscache_set_op_name(&op->op, "Write1");
654
655         ret = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
656         if (ret < 0)
657                 goto nomem_free;
658
659         ret = -ENOBUFS;
660         spin_lock(&cookie->lock);
661
662         if (hlist_empty(&cookie->backing_objects))
663                 goto nobufs;
664         object = hlist_entry(cookie->backing_objects.first,
665                              struct fscache_object, cookie_link);
666         if (test_bit(FSCACHE_IOERROR, &object->cache->flags))
667                 goto nobufs;
668
669         /* add the page to the pending-storage radix tree on the backing
670          * object */
671         spin_lock(&object->lock);
672
673         _debug("store limit %llx", (unsigned long long) object->store_limit);
674
675         ret = radix_tree_insert(&cookie->stores, page->index, page);
676         if (ret < 0) {
677                 if (ret == -EEXIST)
678                         goto already_queued;
679                 _debug("insert failed %d", ret);
680                 goto nobufs_unlock_obj;
681         }
682
683         radix_tree_tag_set(&cookie->stores, page->index,
684                            FSCACHE_COOKIE_PENDING_TAG);
685         page_cache_get(page);
686
687         /* we only want one writer at a time, but we do need to queue new
688          * writers after exclusive ops */
689         if (test_and_set_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags))
690                 goto already_pending;
691
692         spin_unlock(&object->lock);
693
694         op->op.debug_id = atomic_inc_return(&fscache_op_debug_id);
695         op->store_limit = object->store_limit;
696
697         if (fscache_submit_op(object, &op->op) < 0)
698                 goto submit_failed;
699
700         spin_unlock(&cookie->lock);
701         radix_tree_preload_end();
702         fscache_stat(&fscache_n_store_ops);
703         fscache_stat(&fscache_n_stores_ok);
704
705         /* the slow work queue now carries its own ref on the object */
706         fscache_put_operation(&op->op);
707         _leave(" = 0");
708         return 0;
709
710 already_queued:
711         fscache_stat(&fscache_n_stores_again);
712 already_pending:
713         spin_unlock(&object->lock);
714         spin_unlock(&cookie->lock);
715         radix_tree_preload_end();
716         kfree(op);
717         fscache_stat(&fscache_n_stores_ok);
718         _leave(" = 0");
719         return 0;
720
721 submit_failed:
722         radix_tree_delete(&cookie->stores, page->index);
723         page_cache_release(page);
724         ret = -ENOBUFS;
725         goto nobufs;
726
727 nobufs_unlock_obj:
728         spin_unlock(&object->lock);
729 nobufs:
730         spin_unlock(&cookie->lock);
731         radix_tree_preload_end();
732         kfree(op);
733         fscache_stat(&fscache_n_stores_nobufs);
734         _leave(" = -ENOBUFS");
735         return -ENOBUFS;
736
737 nomem_free:
738         kfree(op);
739 nomem:
740         fscache_stat(&fscache_n_stores_oom);
741         _leave(" = -ENOMEM");
742         return -ENOMEM;
743 }
744 EXPORT_SYMBOL(__fscache_write_page);
745
746 /*
747  * remove a page from the cache
748  */
749 void __fscache_uncache_page(struct fscache_cookie *cookie, struct page *page)
750 {
751         struct fscache_object *object;
752
753         _enter(",%p", page);
754
755         ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
756         ASSERTCMP(page, !=, NULL);
757
758         fscache_stat(&fscache_n_uncaches);
759
760         /* cache withdrawal may beat us to it */
761         if (!PageFsCache(page))
762                 goto done;
763
764         /* get the object */
765         spin_lock(&cookie->lock);
766
767         if (hlist_empty(&cookie->backing_objects)) {
768                 ClearPageFsCache(page);
769                 goto done_unlock;
770         }
771
772         object = hlist_entry(cookie->backing_objects.first,
773                              struct fscache_object, cookie_link);
774
775         /* there might now be stuff on disk we could read */
776         clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
777
778         /* only invoke the cache backend if we managed to mark the page
779          * uncached here; this deals with synchronisation vs withdrawal */
780         if (TestClearPageFsCache(page) &&
781             object->cache->ops->uncache_page) {
782                 /* the cache backend releases the cookie lock */
783                 object->cache->ops->uncache_page(object, page);
784                 goto done;
785         }
786
787 done_unlock:
788         spin_unlock(&cookie->lock);
789 done:
790         _leave("");
791 }
792 EXPORT_SYMBOL(__fscache_uncache_page);
793
794 /**
795  * fscache_mark_pages_cached - Mark pages as being cached
796  * @op: The retrieval op pages are being marked for
797  * @pagevec: The pages to be marked
798  *
799  * Mark a bunch of netfs pages as being cached.  After this is called,
800  * the netfs must call fscache_uncache_page() to remove the mark.
801  */
802 void fscache_mark_pages_cached(struct fscache_retrieval *op,
803                                struct pagevec *pagevec)
804 {
805         struct fscache_cookie *cookie = op->op.object->cookie;
806         unsigned long loop;
807
808 #ifdef CONFIG_FSCACHE_STATS
809         atomic_add(pagevec->nr, &fscache_n_marks);
810 #endif
811
812         for (loop = 0; loop < pagevec->nr; loop++) {
813                 struct page *page = pagevec->pages[loop];
814
815                 _debug("- mark %p{%lx}", page, page->index);
816                 if (TestSetPageFsCache(page)) {
817                         static bool once_only;
818                         if (!once_only) {
819                                 once_only = true;
820                                 printk(KERN_WARNING "FS-Cache:"
821                                        " Cookie type %s marked page %lx"
822                                        " multiple times\n",
823                                        cookie->def->name, page->index);
824                         }
825                 }
826         }
827
828         if (cookie->def->mark_pages_cached)
829                 cookie->def->mark_pages_cached(cookie->netfs_data,
830                                                op->mapping, pagevec);
831         pagevec_reinit(pagevec);
832 }
833 EXPORT_SYMBOL(fscache_mark_pages_cached);