diff options
Diffstat (limited to 'fs/fscache')
-rw-r--r-- | fs/fscache/Makefile | 1 | ||||
-rw-r--r-- | fs/fscache/cache.c | 166 | ||||
-rw-r--r-- | fs/fscache/internal.h | 20 |
3 files changed, 187 insertions, 0 deletions
diff --git a/fs/fscache/Makefile b/fs/fscache/Makefile index bc1f3b9d811a..556708bb9796 100644 --- a/fs/fscache/Makefile +++ b/fs/fscache/Makefile | |||
@@ -3,6 +3,7 @@ | |||
3 | # | 3 | # |
4 | 4 | ||
5 | fscache-y := \ | 5 | fscache-y := \ |
6 | cache.o \ | ||
6 | fsdef.o \ | 7 | fsdef.o \ |
7 | main.o | 8 | main.o |
8 | 9 | ||
diff --git a/fs/fscache/cache.c b/fs/fscache/cache.c new file mode 100644 index 000000000000..1a28df36dd93 --- /dev/null +++ b/fs/fscache/cache.c | |||
@@ -0,0 +1,166 @@ | |||
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 | |||
20 | static LIST_HEAD(fscache_cache_tag_list); | ||
21 | |||
22 | /* | ||
23 | * look up a cache tag | ||
24 | */ | ||
25 | struct fscache_cache_tag *__fscache_lookup_cache_tag(const char *name) | ||
26 | { | ||
27 | struct fscache_cache_tag *tag, *xtag; | ||
28 | |||
29 | /* firstly check for the existence of the tag under read lock */ | ||
30 | down_read(&fscache_addremove_sem); | ||
31 | |||
32 | list_for_each_entry(tag, &fscache_cache_tag_list, link) { | ||
33 | if (strcmp(tag->name, name) == 0) { | ||
34 | atomic_inc(&tag->usage); | ||
35 | up_read(&fscache_addremove_sem); | ||
36 | return tag; | ||
37 | } | ||
38 | } | ||
39 | |||
40 | up_read(&fscache_addremove_sem); | ||
41 | |||
42 | /* the tag does not exist - create a candidate */ | ||
43 | xtag = kzalloc(sizeof(*xtag) + strlen(name) + 1, GFP_KERNEL); | ||
44 | if (!xtag) | ||
45 | /* return a dummy tag if out of memory */ | ||
46 | return ERR_PTR(-ENOMEM); | ||
47 | |||
48 | atomic_set(&xtag->usage, 1); | ||
49 | strcpy(xtag->name, name); | ||
50 | |||
51 | /* write lock, search again and add if still not present */ | ||
52 | down_write(&fscache_addremove_sem); | ||
53 | |||
54 | list_for_each_entry(tag, &fscache_cache_tag_list, link) { | ||
55 | if (strcmp(tag->name, name) == 0) { | ||
56 | atomic_inc(&tag->usage); | ||
57 | up_write(&fscache_addremove_sem); | ||
58 | kfree(xtag); | ||
59 | return tag; | ||
60 | } | ||
61 | } | ||
62 | |||
63 | list_add_tail(&xtag->link, &fscache_cache_tag_list); | ||
64 | up_write(&fscache_addremove_sem); | ||
65 | return xtag; | ||
66 | } | ||
67 | |||
68 | /* | ||
69 | * release a reference to a cache tag | ||
70 | */ | ||
71 | void __fscache_release_cache_tag(struct fscache_cache_tag *tag) | ||
72 | { | ||
73 | if (tag != ERR_PTR(-ENOMEM)) { | ||
74 | down_write(&fscache_addremove_sem); | ||
75 | |||
76 | if (atomic_dec_and_test(&tag->usage)) | ||
77 | list_del_init(&tag->link); | ||
78 | else | ||
79 | tag = NULL; | ||
80 | |||
81 | up_write(&fscache_addremove_sem); | ||
82 | |||
83 | kfree(tag); | ||
84 | } | ||
85 | } | ||
86 | |||
87 | /* | ||
88 | * select a cache in which to store an object | ||
89 | * - the cache addremove semaphore must be at least read-locked by the caller | ||
90 | * - the object will never be an index | ||
91 | */ | ||
92 | struct fscache_cache *fscache_select_cache_for_object( | ||
93 | struct fscache_cookie *cookie) | ||
94 | { | ||
95 | struct fscache_cache_tag *tag; | ||
96 | struct fscache_object *object; | ||
97 | struct fscache_cache *cache; | ||
98 | |||
99 | _enter(""); | ||
100 | |||
101 | if (list_empty(&fscache_cache_list)) { | ||
102 | _leave(" = NULL [no cache]"); | ||
103 | return NULL; | ||
104 | } | ||
105 | |||
106 | /* we check the parent to determine the cache to use */ | ||
107 | spin_lock(&cookie->lock); | ||
108 | |||
109 | /* the first in the parent's backing list should be the preferred | ||
110 | * cache */ | ||
111 | if (!hlist_empty(&cookie->backing_objects)) { | ||
112 | object = hlist_entry(cookie->backing_objects.first, | ||
113 | struct fscache_object, cookie_link); | ||
114 | |||
115 | cache = object->cache; | ||
116 | if (object->state >= FSCACHE_OBJECT_DYING || | ||
117 | test_bit(FSCACHE_IOERROR, &cache->flags)) | ||
118 | cache = NULL; | ||
119 | |||
120 | spin_unlock(&cookie->lock); | ||
121 | _leave(" = %p [parent]", cache); | ||
122 | return cache; | ||
123 | } | ||
124 | |||
125 | /* the parent is unbacked */ | ||
126 | if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) { | ||
127 | /* cookie not an index and is unbacked */ | ||
128 | spin_unlock(&cookie->lock); | ||
129 | _leave(" = NULL [cookie ub,ni]"); | ||
130 | return NULL; | ||
131 | } | ||
132 | |||
133 | spin_unlock(&cookie->lock); | ||
134 | |||
135 | if (!cookie->def->select_cache) | ||
136 | goto no_preference; | ||
137 | |||
138 | /* ask the netfs for its preference */ | ||
139 | tag = cookie->def->select_cache(cookie->parent->netfs_data, | ||
140 | cookie->netfs_data); | ||
141 | if (!tag) | ||
142 | goto no_preference; | ||
143 | |||
144 | if (tag == ERR_PTR(-ENOMEM)) { | ||
145 | _leave(" = NULL [nomem tag]"); | ||
146 | return NULL; | ||
147 | } | ||
148 | |||
149 | if (!tag->cache) { | ||
150 | _leave(" = NULL [unbacked tag]"); | ||
151 | return NULL; | ||
152 | } | ||
153 | |||
154 | if (test_bit(FSCACHE_IOERROR, &tag->cache->flags)) | ||
155 | return NULL; | ||
156 | |||
157 | _leave(" = %p [specific]", tag->cache); | ||
158 | return tag->cache; | ||
159 | |||
160 | no_preference: | ||
161 | /* netfs has no preference - just select first cache */ | ||
162 | cache = list_entry(fscache_cache_list.next, | ||
163 | struct fscache_cache, link); | ||
164 | _leave(" = %p [first]", cache); | ||
165 | return cache; | ||
166 | } | ||
diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h index 4113af8d1660..0a2069afa417 100644 --- a/fs/fscache/internal.h +++ b/fs/fscache/internal.h | |||
@@ -28,6 +28,15 @@ | |||
28 | #define FSCACHE_MAX_THREADS 32 | 28 | #define FSCACHE_MAX_THREADS 32 |
29 | 29 | ||
30 | /* | 30 | /* |
31 | * fsc-cache.c | ||
32 | */ | ||
33 | extern struct list_head fscache_cache_list; | ||
34 | extern struct rw_semaphore fscache_addremove_sem; | ||
35 | |||
36 | extern struct fscache_cache *fscache_select_cache_for_object( | ||
37 | struct fscache_cookie *); | ||
38 | |||
39 | /* | ||
31 | * fsc-fsdef.c | 40 | * fsc-fsdef.c |
32 | */ | 41 | */ |
33 | extern struct fscache_cookie fscache_fsdef_index; | 42 | extern struct fscache_cookie fscache_fsdef_index; |
@@ -168,6 +177,17 @@ extern const struct file_operations fscache_stats_fops; | |||
168 | #define fscache_stat(stat) do {} while (0) | 177 | #define fscache_stat(stat) do {} while (0) |
169 | #endif | 178 | #endif |
170 | 179 | ||
180 | /* | ||
181 | * raise an event on an object | ||
182 | * - if the event is not masked for that object, then the object is | ||
183 | * queued for attention by the thread pool. | ||
184 | */ | ||
185 | static inline void fscache_raise_event(struct fscache_object *object, | ||
186 | unsigned event) | ||
187 | { | ||
188 | BUG(); // TODO | ||
189 | } | ||
190 | |||
171 | /*****************************************************************************/ | 191 | /*****************************************************************************/ |
172 | /* | 192 | /* |
173 | * debug tracing | 193 | * debug tracing |