~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/fs/fscache/cache.c

Version: ~ [ linux-5.11-rc3 ] ~ [ linux-5.10.7 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.89 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.167 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.215 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.251 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.251 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.85 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 /* FS-Cache cache handling
  2  *
  3  * Copyright (C) 2007 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 CACHE
 13 #include <linux/module.h>
 14 #include <linux/slab.h>
 15 #include "internal.h"
 16 
 17 LIST_HEAD(fscache_cache_list);
 18 DECLARE_RWSEM(fscache_addremove_sem);
 19 DECLARE_WAIT_QUEUE_HEAD(fscache_cache_cleared_wq);
 20 EXPORT_SYMBOL(fscache_cache_cleared_wq);
 21 
 22 static LIST_HEAD(fscache_cache_tag_list);
 23 
 24 /*
 25  * look up a cache tag
 26  */
 27 struct fscache_cache_tag *__fscache_lookup_cache_tag(const char *name)
 28 {
 29         struct fscache_cache_tag *tag, *xtag;
 30 
 31         /* firstly check for the existence of the tag under read lock */
 32         down_read(&fscache_addremove_sem);
 33 
 34         list_for_each_entry(tag, &fscache_cache_tag_list, link) {
 35                 if (strcmp(tag->name, name) == 0) {
 36                         atomic_inc(&tag->usage);
 37                         up_read(&fscache_addremove_sem);
 38                         return tag;
 39                 }
 40         }
 41 
 42         up_read(&fscache_addremove_sem);
 43 
 44         /* the tag does not exist - create a candidate */
 45         xtag = kzalloc(sizeof(*xtag) + strlen(name) + 1, GFP_KERNEL);
 46         if (!xtag)
 47                 /* return a dummy tag if out of memory */
 48                 return ERR_PTR(-ENOMEM);
 49 
 50         atomic_set(&xtag->usage, 1);
 51         strcpy(xtag->name, name);
 52 
 53         /* write lock, search again and add if still not present */
 54         down_write(&fscache_addremove_sem);
 55 
 56         list_for_each_entry(tag, &fscache_cache_tag_list, link) {
 57                 if (strcmp(tag->name, name) == 0) {
 58                         atomic_inc(&tag->usage);
 59                         up_write(&fscache_addremove_sem);
 60                         kfree(xtag);
 61                         return tag;
 62                 }
 63         }
 64 
 65         list_add_tail(&xtag->link, &fscache_cache_tag_list);
 66         up_write(&fscache_addremove_sem);
 67         return xtag;
 68 }
 69 
 70 /*
 71  * release a reference to a cache tag
 72  */
 73 void __fscache_release_cache_tag(struct fscache_cache_tag *tag)
 74 {
 75         if (tag != ERR_PTR(-ENOMEM)) {
 76                 down_write(&fscache_addremove_sem);
 77 
 78                 if (atomic_dec_and_test(&tag->usage))
 79                         list_del_init(&tag->link);
 80                 else
 81                         tag = NULL;
 82 
 83                 up_write(&fscache_addremove_sem);
 84 
 85                 kfree(tag);
 86         }
 87 }
 88 
 89 /*
 90  * select a cache in which to store an object
 91  * - the cache addremove semaphore must be at least read-locked by the caller
 92  * - the object will never be an index
 93  */
 94 struct fscache_cache *fscache_select_cache_for_object(
 95         struct fscache_cookie *cookie)
 96 {
 97         struct fscache_cache_tag *tag;
 98         struct fscache_object *object;
 99         struct fscache_cache *cache;
100 
101         _enter("");
102 
103         if (list_empty(&fscache_cache_list)) {
104                 _leave(" = NULL [no cache]");
105                 return NULL;
106         }
107 
108         /* we check the parent to determine the cache to use */
109         spin_lock(&cookie->lock);
110 
111         /* the first in the parent's backing list should be the preferred
112          * cache */
113         if (!hlist_empty(&cookie->backing_objects)) {
114                 object = hlist_entry(cookie->backing_objects.first,
115                                      struct fscache_object, cookie_link);
116 
117                 cache = object->cache;
118                 if (fscache_object_is_dying(object) ||
119                     test_bit(FSCACHE_IOERROR, &cache->flags))
120                         cache = NULL;
121 
122                 spin_unlock(&cookie->lock);
123                 _leave(" = %p [parent]", cache);
124                 return cache;
125         }
126 
127         /* the parent is unbacked */
128         if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) {
129                 /* cookie not an index and is unbacked */
130                 spin_unlock(&cookie->lock);
131                 _leave(" = NULL [cookie ub,ni]");
132                 return NULL;
133         }
134 
135         spin_unlock(&cookie->lock);
136 
137         if (!cookie->def->select_cache)
138                 goto no_preference;
139 
140         /* ask the netfs for its preference */
141         tag = cookie->def->select_cache(cookie->parent->netfs_data,
142                                         cookie->netfs_data);
143         if (!tag)
144                 goto no_preference;
145 
146         if (tag == ERR_PTR(-ENOMEM)) {
147                 _leave(" = NULL [nomem tag]");
148                 return NULL;
149         }
150 
151         if (!tag->cache) {
152                 _leave(" = NULL [unbacked tag]");
153                 return NULL;
154         }
155 
156         if (test_bit(FSCACHE_IOERROR, &tag->cache->flags))
157                 return NULL;
158 
159         _leave(" = %p [specific]", tag->cache);
160         return tag->cache;
161 
162 no_preference:
163         /* netfs has no preference - just select first cache */
164         cache = list_entry(fscache_cache_list.next,
165                            struct fscache_cache, link);
166         _leave(" = %p [first]", cache);
167         return cache;
168 }
169 
170 /**
171  * fscache_init_cache - Initialise a cache record
172  * @cache: The cache record to be initialised
173  * @ops: The cache operations to be installed in that record
174  * @idfmt: Format string to define identifier
175  * @...: sprintf-style arguments
176  *
177  * Initialise a record of a cache and fill in the name.
178  *
179  * See Documentation/filesystems/caching/backend-api.txt for a complete
180  * description.
181  */
182 void fscache_init_cache(struct fscache_cache *cache,
183                         const struct fscache_cache_ops *ops,
184                         const char *idfmt,
185                         ...)
186 {
187         va_list va;
188 
189         memset(cache, 0, sizeof(*cache));
190 
191         cache->ops = ops;
192 
193         va_start(va, idfmt);
194         vsnprintf(cache->identifier, sizeof(cache->identifier), idfmt, va);
195         va_end(va);
196 
197         INIT_WORK(&cache->op_gc, fscache_operation_gc);
198         INIT_LIST_HEAD(&cache->link);
199         INIT_LIST_HEAD(&cache->object_list);
200         INIT_LIST_HEAD(&cache->op_gc_list);
201         spin_lock_init(&cache->object_list_lock);
202         spin_lock_init(&cache->op_gc_list_lock);
203 }
204 EXPORT_SYMBOL(fscache_init_cache);
205 
206 /**
207  * fscache_add_cache - Declare a cache as being open for business
208  * @cache: The record describing the cache
209  * @ifsdef: The record of the cache object describing the top-level index
210  * @tagname: The tag describing this cache
211  *
212  * Add a cache to the system, making it available for netfs's to use.
213  *
214  * See Documentation/filesystems/caching/backend-api.txt for a complete
215  * description.
216  */
217 int fscache_add_cache(struct fscache_cache *cache,
218                       struct fscache_object *ifsdef,
219                       const char *tagname)
220 {
221         struct fscache_cache_tag *tag;
222 
223         BUG_ON(!cache->ops);
224         BUG_ON(!ifsdef);
225 
226         cache->flags = 0;
227         ifsdef->event_mask =
228                 ((1 << NR_FSCACHE_OBJECT_EVENTS) - 1) &
229                 ~(1 << FSCACHE_OBJECT_EV_CLEARED);
230         __set_bit(FSCACHE_OBJECT_IS_AVAILABLE, &ifsdef->flags);
231 
232         if (!tagname)
233                 tagname = cache->identifier;
234 
235         BUG_ON(!tagname[0]);
236 
237         _enter("{%s.%s},,%s", cache->ops->name, cache->identifier, tagname);
238 
239         /* we use the cache tag to uniquely identify caches */
240         tag = __fscache_lookup_cache_tag(tagname);
241         if (IS_ERR(tag))
242                 goto nomem;
243 
244         if (test_and_set_bit(FSCACHE_TAG_RESERVED, &tag->flags))
245                 goto tag_in_use;
246 
247         cache->kobj = kobject_create_and_add(tagname, fscache_root);
248         if (!cache->kobj)
249                 goto error;
250 
251         ifsdef->cookie = &fscache_fsdef_index;
252         ifsdef->cache = cache;
253         cache->fsdef = ifsdef;
254 
255         down_write(&fscache_addremove_sem);
256 
257         tag->cache = cache;
258         cache->tag = tag;
259 
260         /* add the cache to the list */
261         list_add(&cache->link, &fscache_cache_list);
262 
263         /* add the cache's netfs definition index object to the cache's
264          * list */
265         spin_lock(&cache->object_list_lock);
266         list_add_tail(&ifsdef->cache_link, &cache->object_list);
267         spin_unlock(&cache->object_list_lock);
268         fscache_objlist_add(ifsdef);
269 
270         /* add the cache's netfs definition index object to the top level index
271          * cookie as a known backing object */
272         spin_lock(&fscache_fsdef_index.lock);
273 
274         hlist_add_head(&ifsdef->cookie_link,
275                        &fscache_fsdef_index.backing_objects);
276 
277         atomic_inc(&fscache_fsdef_index.usage);
278 
279         /* done */
280         spin_unlock(&fscache_fsdef_index.lock);
281         up_write(&fscache_addremove_sem);
282 
283         printk(KERN_NOTICE "FS-Cache: Cache \"%s\" added (type %s)\n",
284                cache->tag->name, cache->ops->name);
285         kobject_uevent(cache->kobj, KOBJ_ADD);
286 
287         _leave(" = 0 [%s]", cache->identifier);
288         return 0;
289 
290 tag_in_use:
291         printk(KERN_ERR "FS-Cache: Cache tag '%s' already in use\n", tagname);
292         __fscache_release_cache_tag(tag);
293         _leave(" = -EXIST");
294         return -EEXIST;
295 
296 error:
297         __fscache_release_cache_tag(tag);
298         _leave(" = -EINVAL");
299         return -EINVAL;
300 
301 nomem:
302         _leave(" = -ENOMEM");
303         return -ENOMEM;
304 }
305 EXPORT_SYMBOL(fscache_add_cache);
306 
307 /**
308  * fscache_io_error - Note a cache I/O error
309  * @cache: The record describing the cache
310  *
311  * Note that an I/O error occurred in a cache and that it should no longer be
312  * used for anything.  This also reports the error into the kernel log.
313  *
314  * See Documentation/filesystems/caching/backend-api.txt for a complete
315  * description.
316  */
317 void fscache_io_error(struct fscache_cache *cache)
318 {
319         if (!test_and_set_bit(FSCACHE_IOERROR, &cache->flags))
320                 printk(KERN_ERR "FS-Cache:"
321                        " Cache '%s' stopped due to I/O error\n",
322                        cache->ops->name);
323 }
324 EXPORT_SYMBOL(fscache_io_error);
325 
326 /*
327  * request withdrawal of all the objects in a cache
328  * - all the objects being withdrawn are moved onto the supplied list
329  */
330 static void fscache_withdraw_all_objects(struct fscache_cache *cache,
331                                          struct list_head *dying_objects)
332 {
333         struct fscache_object *object;
334 
335         while (!list_empty(&cache->object_list)) {
336                 spin_lock(&cache->object_list_lock);
337 
338                 if (!list_empty(&cache->object_list)) {
339                         object = list_entry(cache->object_list.next,
340                                             struct fscache_object, cache_link);
341                         list_move_tail(&object->cache_link, dying_objects);
342 
343                         _debug("withdraw %p", object->cookie);
344 
345                         /* This must be done under object_list_lock to prevent
346                          * a race with fscache_drop_object().
347                          */
348                         fscache_raise_event(object, FSCACHE_OBJECT_EV_KILL);
349                 }
350 
351                 spin_unlock(&cache->object_list_lock);
352                 cond_resched();
353         }
354 }
355 
356 /**
357  * fscache_withdraw_cache - Withdraw a cache from the active service
358  * @cache: The record describing the cache
359  *
360  * Withdraw a cache from service, unbinding all its cache objects from the
361  * netfs cookies they're currently representing.
362  *
363  * See Documentation/filesystems/caching/backend-api.txt for a complete
364  * description.
365  */
366 void fscache_withdraw_cache(struct fscache_cache *cache)
367 {
368         LIST_HEAD(dying_objects);
369 
370         _enter("");
371 
372         printk(KERN_NOTICE "FS-Cache: Withdrawing cache \"%s\"\n",
373                cache->tag->name);
374 
375         /* make the cache unavailable for cookie acquisition */
376         if (test_and_set_bit(FSCACHE_CACHE_WITHDRAWN, &cache->flags))
377                 BUG();
378 
379         down_write(&fscache_addremove_sem);
380         list_del_init(&cache->link);
381         cache->tag->cache = NULL;
382         up_write(&fscache_addremove_sem);
383 
384         /* make sure all pages pinned by operations on behalf of the netfs are
385          * written to disk */
386         fscache_stat(&fscache_n_cop_sync_cache);
387         cache->ops->sync_cache(cache);
388         fscache_stat_d(&fscache_n_cop_sync_cache);
389 
390         /* dissociate all the netfs pages backed by this cache from the block
391          * mappings in the cache */
392         fscache_stat(&fscache_n_cop_dissociate_pages);
393         cache->ops->dissociate_pages(cache);
394         fscache_stat_d(&fscache_n_cop_dissociate_pages);
395 
396         /* we now have to destroy all the active objects pertaining to this
397          * cache - which we do by passing them off to thread pool to be
398          * disposed of */
399         _debug("destroy");
400 
401         fscache_withdraw_all_objects(cache, &dying_objects);
402 
403         /* wait for all extant objects to finish their outstanding operations
404          * and go away */
405         _debug("wait for finish");
406         wait_event(fscache_cache_cleared_wq,
407                    atomic_read(&cache->object_count) == 0);
408         _debug("wait for clearance");
409         wait_event(fscache_cache_cleared_wq,
410                    list_empty(&cache->object_list));
411         _debug("cleared");
412         ASSERT(list_empty(&dying_objects));
413 
414         kobject_put(cache->kobj);
415 
416         clear_bit(FSCACHE_TAG_RESERVED, &cache->tag->flags);
417         fscache_release_cache_tag(cache->tag);
418         cache->tag = NULL;
419 
420         _leave("");
421 }
422 EXPORT_SYMBOL(fscache_withdraw_cache);
423 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp