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9ae326a6 DH |
1 | /* CacheFiles extended attribute management |
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 Licence | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the Licence, or (at your option) any later version. | |
10 | */ | |
11 | ||
12 | #include <linux/module.h> | |
13 | #include <linux/sched.h> | |
14 | #include <linux/file.h> | |
15 | #include <linux/fs.h> | |
16 | #include <linux/fsnotify.h> | |
17 | #include <linux/quotaops.h> | |
18 | #include <linux/xattr.h> | |
19 | #include "internal.h" | |
20 | ||
21 | static const char cachefiles_xattr_cache[] = | |
22 | XATTR_USER_PREFIX "CacheFiles.cache"; | |
23 | ||
24 | /* | |
25 | * check the type label on an object | |
26 | * - done using xattrs | |
27 | */ | |
28 | int cachefiles_check_object_type(struct cachefiles_object *object) | |
29 | { | |
30 | struct dentry *dentry = object->dentry; | |
31 | char type[3], xtype[3]; | |
32 | int ret; | |
33 | ||
34 | ASSERT(dentry); | |
35 | ASSERT(dentry->d_inode); | |
36 | ||
37 | if (!object->fscache.cookie) | |
38 | strcpy(type, "C3"); | |
39 | else | |
40 | snprintf(type, 3, "%02x", object->fscache.cookie->def->type); | |
41 | ||
42 | _enter("%p{%s}", object, type); | |
43 | ||
44 | /* attempt to install a type label directly */ | |
45 | ret = vfs_setxattr(dentry, cachefiles_xattr_cache, type, 2, | |
46 | XATTR_CREATE); | |
47 | if (ret == 0) { | |
48 | _debug("SET"); /* we succeeded */ | |
49 | goto error; | |
50 | } | |
51 | ||
52 | if (ret != -EEXIST) { | |
53 | kerror("Can't set xattr on %*.*s [%lu] (err %d)", | |
54 | dentry->d_name.len, dentry->d_name.len, | |
55 | dentry->d_name.name, dentry->d_inode->i_ino, | |
56 | -ret); | |
57 | goto error; | |
58 | } | |
59 | ||
60 | /* read the current type label */ | |
61 | ret = vfs_getxattr(dentry, cachefiles_xattr_cache, xtype, 3); | |
62 | if (ret < 0) { | |
63 | if (ret == -ERANGE) | |
64 | goto bad_type_length; | |
65 | ||
66 | kerror("Can't read xattr on %*.*s [%lu] (err %d)", | |
67 | dentry->d_name.len, dentry->d_name.len, | |
68 | dentry->d_name.name, dentry->d_inode->i_ino, | |
69 | -ret); | |
70 | goto error; | |
71 | } | |
72 | ||
73 | /* check the type is what we're expecting */ | |
74 | if (ret != 2) | |
75 | goto bad_type_length; | |
76 | ||
77 | if (xtype[0] != type[0] || xtype[1] != type[1]) | |
78 | goto bad_type; | |
79 | ||
80 | ret = 0; | |
81 | ||
82 | error: | |
83 | _leave(" = %d", ret); | |
84 | return ret; | |
85 | ||
86 | bad_type_length: | |
87 | kerror("Cache object %lu type xattr length incorrect", | |
88 | dentry->d_inode->i_ino); | |
89 | ret = -EIO; | |
90 | goto error; | |
91 | ||
92 | bad_type: | |
93 | xtype[2] = 0; | |
94 | kerror("Cache object %*.*s [%lu] type %s not %s", | |
95 | dentry->d_name.len, dentry->d_name.len, | |
96 | dentry->d_name.name, dentry->d_inode->i_ino, | |
97 | xtype, type); | |
98 | ret = -EIO; | |
99 | goto error; | |
100 | } | |
101 | ||
102 | /* | |
103 | * set the state xattr on a cache file | |
104 | */ | |
105 | int cachefiles_set_object_xattr(struct cachefiles_object *object, | |
106 | struct cachefiles_xattr *auxdata) | |
107 | { | |
108 | struct dentry *dentry = object->dentry; | |
109 | int ret; | |
110 | ||
111 | ASSERT(object->fscache.cookie); | |
112 | ASSERT(dentry); | |
113 | ||
114 | _enter("%p,#%d", object, auxdata->len); | |
115 | ||
116 | /* attempt to install the cache metadata directly */ | |
117 | _debug("SET %s #%u", object->fscache.cookie->def->name, auxdata->len); | |
118 | ||
119 | ret = vfs_setxattr(dentry, cachefiles_xattr_cache, | |
120 | &auxdata->type, auxdata->len, | |
121 | XATTR_CREATE); | |
122 | if (ret < 0 && ret != -ENOMEM) | |
123 | cachefiles_io_error_obj( | |
124 | object, | |
125 | "Failed to set xattr with error %d", ret); | |
126 | ||
127 | _leave(" = %d", ret); | |
128 | return ret; | |
129 | } | |
130 | ||
131 | /* | |
132 | * update the state xattr on a cache file | |
133 | */ | |
134 | int cachefiles_update_object_xattr(struct cachefiles_object *object, | |
135 | struct cachefiles_xattr *auxdata) | |
136 | { | |
137 | struct dentry *dentry = object->dentry; | |
138 | int ret; | |
139 | ||
140 | ASSERT(object->fscache.cookie); | |
141 | ASSERT(dentry); | |
142 | ||
143 | _enter("%p,#%d", object, auxdata->len); | |
144 | ||
145 | /* attempt to install the cache metadata directly */ | |
146 | _debug("SET %s #%u", object->fscache.cookie->def->name, auxdata->len); | |
147 | ||
148 | ret = vfs_setxattr(dentry, cachefiles_xattr_cache, | |
149 | &auxdata->type, auxdata->len, | |
150 | XATTR_REPLACE); | |
151 | if (ret < 0 && ret != -ENOMEM) | |
152 | cachefiles_io_error_obj( | |
153 | object, | |
154 | "Failed to update xattr with error %d", ret); | |
155 | ||
156 | _leave(" = %d", ret); | |
157 | return ret; | |
158 | } | |
159 | ||
160 | /* | |
161 | * check the state xattr on a cache file | |
162 | * - return -ESTALE if the object should be deleted | |
163 | */ | |
164 | int cachefiles_check_object_xattr(struct cachefiles_object *object, | |
165 | struct cachefiles_xattr *auxdata) | |
166 | { | |
167 | struct cachefiles_xattr *auxbuf; | |
168 | struct dentry *dentry = object->dentry; | |
169 | int ret; | |
170 | ||
171 | _enter("%p,#%d", object, auxdata->len); | |
172 | ||
173 | ASSERT(dentry); | |
174 | ASSERT(dentry->d_inode); | |
175 | ||
176 | auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, GFP_KERNEL); | |
177 | if (!auxbuf) { | |
178 | _leave(" = -ENOMEM"); | |
179 | return -ENOMEM; | |
180 | } | |
181 | ||
182 | /* read the current type label */ | |
183 | ret = vfs_getxattr(dentry, cachefiles_xattr_cache, | |
184 | &auxbuf->type, 512 + 1); | |
185 | if (ret < 0) { | |
186 | if (ret == -ENODATA) | |
187 | goto stale; /* no attribute - power went off | |
188 | * mid-cull? */ | |
189 | ||
190 | if (ret == -ERANGE) | |
191 | goto bad_type_length; | |
192 | ||
193 | cachefiles_io_error_obj(object, | |
194 | "Can't read xattr on %lu (err %d)", | |
195 | dentry->d_inode->i_ino, -ret); | |
196 | goto error; | |
197 | } | |
198 | ||
199 | /* check the on-disk object */ | |
200 | if (ret < 1) | |
201 | goto bad_type_length; | |
202 | ||
203 | if (auxbuf->type != auxdata->type) | |
204 | goto stale; | |
205 | ||
206 | auxbuf->len = ret; | |
207 | ||
208 | /* consult the netfs */ | |
209 | if (object->fscache.cookie->def->check_aux) { | |
210 | enum fscache_checkaux result; | |
211 | unsigned int dlen; | |
212 | ||
213 | dlen = auxbuf->len - 1; | |
214 | ||
215 | _debug("checkaux %s #%u", | |
216 | object->fscache.cookie->def->name, dlen); | |
217 | ||
218 | result = fscache_check_aux(&object->fscache, | |
219 | &auxbuf->data, dlen); | |
220 | ||
221 | switch (result) { | |
222 | /* entry okay as is */ | |
223 | case FSCACHE_CHECKAUX_OKAY: | |
224 | goto okay; | |
225 | ||
226 | /* entry requires update */ | |
227 | case FSCACHE_CHECKAUX_NEEDS_UPDATE: | |
228 | break; | |
229 | ||
230 | /* entry requires deletion */ | |
231 | case FSCACHE_CHECKAUX_OBSOLETE: | |
232 | goto stale; | |
233 | ||
234 | default: | |
235 | BUG(); | |
236 | } | |
237 | ||
238 | /* update the current label */ | |
239 | ret = vfs_setxattr(dentry, cachefiles_xattr_cache, | |
240 | &auxdata->type, auxdata->len, | |
241 | XATTR_REPLACE); | |
242 | if (ret < 0) { | |
243 | cachefiles_io_error_obj(object, | |
244 | "Can't update xattr on %lu" | |
245 | " (error %d)", | |
246 | dentry->d_inode->i_ino, -ret); | |
247 | goto error; | |
248 | } | |
249 | } | |
250 | ||
251 | okay: | |
252 | ret = 0; | |
253 | ||
254 | error: | |
255 | kfree(auxbuf); | |
256 | _leave(" = %d", ret); | |
257 | return ret; | |
258 | ||
259 | bad_type_length: | |
260 | kerror("Cache object %lu xattr length incorrect", | |
261 | dentry->d_inode->i_ino); | |
262 | ret = -EIO; | |
263 | goto error; | |
264 | ||
265 | stale: | |
266 | ret = -ESTALE; | |
267 | goto error; | |
268 | } | |
269 | ||
270 | /* | |
271 | * remove the object's xattr to mark it stale | |
272 | */ | |
273 | int cachefiles_remove_object_xattr(struct cachefiles_cache *cache, | |
274 | struct dentry *dentry) | |
275 | { | |
276 | int ret; | |
277 | ||
278 | ret = vfs_removexattr(dentry, cachefiles_xattr_cache); | |
279 | if (ret < 0) { | |
280 | if (ret == -ENOENT || ret == -ENODATA) | |
281 | ret = 0; | |
282 | else if (ret != -ENOMEM) | |
283 | cachefiles_io_error(cache, | |
284 | "Can't remove xattr from %lu" | |
285 | " (error %d)", | |
286 | dentry->d_inode->i_ino, -ret); | |
287 | } | |
288 | ||
289 | _leave(" = %d", ret); | |
290 | return ret; | |
291 | } |