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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> | |
5a0e3ad6 | 19 | #include <linux/slab.h> |
9ae326a6 DH |
20 | #include "internal.h" |
21 | ||
22 | static const char cachefiles_xattr_cache[] = | |
23 | XATTR_USER_PREFIX "CacheFiles.cache"; | |
24 | ||
25 | /* | |
26 | * check the type label on an object | |
27 | * - done using xattrs | |
28 | */ | |
29 | int cachefiles_check_object_type(struct cachefiles_object *object) | |
30 | { | |
31 | struct dentry *dentry = object->dentry; | |
32 | char type[3], xtype[3]; | |
33 | int ret; | |
34 | ||
35 | ASSERT(dentry); | |
36 | ASSERT(dentry->d_inode); | |
37 | ||
38 | if (!object->fscache.cookie) | |
39 | strcpy(type, "C3"); | |
40 | else | |
41 | snprintf(type, 3, "%02x", object->fscache.cookie->def->type); | |
42 | ||
43 | _enter("%p{%s}", object, type); | |
44 | ||
45 | /* attempt to install a type label directly */ | |
46 | ret = vfs_setxattr(dentry, cachefiles_xattr_cache, type, 2, | |
47 | XATTR_CREATE); | |
48 | if (ret == 0) { | |
49 | _debug("SET"); /* we succeeded */ | |
50 | goto error; | |
51 | } | |
52 | ||
53 | if (ret != -EEXIST) { | |
54 | kerror("Can't set xattr on %*.*s [%lu] (err %d)", | |
55 | dentry->d_name.len, dentry->d_name.len, | |
56 | dentry->d_name.name, dentry->d_inode->i_ino, | |
57 | -ret); | |
58 | goto error; | |
59 | } | |
60 | ||
61 | /* read the current type label */ | |
62 | ret = vfs_getxattr(dentry, cachefiles_xattr_cache, xtype, 3); | |
63 | if (ret < 0) { | |
64 | if (ret == -ERANGE) | |
65 | goto bad_type_length; | |
66 | ||
67 | kerror("Can't read xattr on %*.*s [%lu] (err %d)", | |
68 | dentry->d_name.len, dentry->d_name.len, | |
69 | dentry->d_name.name, dentry->d_inode->i_ino, | |
70 | -ret); | |
71 | goto error; | |
72 | } | |
73 | ||
74 | /* check the type is what we're expecting */ | |
75 | if (ret != 2) | |
76 | goto bad_type_length; | |
77 | ||
78 | if (xtype[0] != type[0] || xtype[1] != type[1]) | |
79 | goto bad_type; | |
80 | ||
81 | ret = 0; | |
82 | ||
83 | error: | |
84 | _leave(" = %d", ret); | |
85 | return ret; | |
86 | ||
87 | bad_type_length: | |
88 | kerror("Cache object %lu type xattr length incorrect", | |
89 | dentry->d_inode->i_ino); | |
90 | ret = -EIO; | |
91 | goto error; | |
92 | ||
93 | bad_type: | |
94 | xtype[2] = 0; | |
95 | kerror("Cache object %*.*s [%lu] type %s not %s", | |
96 | dentry->d_name.len, dentry->d_name.len, | |
97 | dentry->d_name.name, dentry->d_inode->i_ino, | |
98 | xtype, type); | |
99 | ret = -EIO; | |
100 | goto error; | |
101 | } | |
102 | ||
103 | /* | |
104 | * set the state xattr on a cache file | |
105 | */ | |
106 | int cachefiles_set_object_xattr(struct cachefiles_object *object, | |
107 | struct cachefiles_xattr *auxdata) | |
108 | { | |
109 | struct dentry *dentry = object->dentry; | |
110 | int ret; | |
111 | ||
9ae326a6 DH |
112 | ASSERT(dentry); |
113 | ||
114 | _enter("%p,#%d", object, auxdata->len); | |
115 | ||
116 | /* attempt to install the cache metadata directly */ | |
1362729b | 117 | _debug("SET #%u", auxdata->len); |
9ae326a6 DH |
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 | ||
9ae326a6 DH |
140 | ASSERT(dentry); |
141 | ||
142 | _enter("%p,#%d", object, auxdata->len); | |
143 | ||
144 | /* attempt to install the cache metadata directly */ | |
1362729b | 145 | _debug("SET #%u", auxdata->len); |
9ae326a6 DH |
146 | |
147 | ret = vfs_setxattr(dentry, cachefiles_xattr_cache, | |
148 | &auxdata->type, auxdata->len, | |
149 | XATTR_REPLACE); | |
150 | if (ret < 0 && ret != -ENOMEM) | |
151 | cachefiles_io_error_obj( | |
152 | object, | |
153 | "Failed to update xattr with error %d", ret); | |
154 | ||
155 | _leave(" = %d", ret); | |
156 | return ret; | |
157 | } | |
158 | ||
5002d7be DH |
159 | /* |
160 | * check the consistency between the backing cache and the FS-Cache cookie | |
161 | */ | |
162 | int cachefiles_check_auxdata(struct cachefiles_object *object) | |
163 | { | |
164 | struct cachefiles_xattr *auxbuf; | |
607566ae | 165 | enum fscache_checkaux validity; |
5002d7be | 166 | struct dentry *dentry = object->dentry; |
607566ae | 167 | ssize_t xlen; |
5002d7be DH |
168 | int ret; |
169 | ||
170 | ASSERT(dentry); | |
171 | ASSERT(dentry->d_inode); | |
172 | ASSERT(object->fscache.cookie->def->check_aux); | |
173 | ||
174 | auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, GFP_KERNEL); | |
175 | if (!auxbuf) | |
176 | return -ENOMEM; | |
177 | ||
607566ae JB |
178 | xlen = vfs_getxattr(dentry, cachefiles_xattr_cache, |
179 | &auxbuf->type, 512 + 1); | |
180 | ret = -ESTALE; | |
181 | if (xlen < 1 || | |
182 | auxbuf->type != object->fscache.cookie->def->type) | |
183 | goto error; | |
5002d7be | 184 | |
607566ae JB |
185 | xlen--; |
186 | validity = fscache_check_aux(&object->fscache, &auxbuf->data, xlen); | |
187 | if (validity != FSCACHE_CHECKAUX_OKAY) | |
188 | goto error; | |
5002d7be | 189 | |
607566ae JB |
190 | ret = 0; |
191 | error: | |
5002d7be | 192 | kfree(auxbuf); |
607566ae | 193 | return ret; |
5002d7be DH |
194 | } |
195 | ||
9ae326a6 DH |
196 | /* |
197 | * check the state xattr on a cache file | |
198 | * - return -ESTALE if the object should be deleted | |
199 | */ | |
200 | int cachefiles_check_object_xattr(struct cachefiles_object *object, | |
201 | struct cachefiles_xattr *auxdata) | |
202 | { | |
203 | struct cachefiles_xattr *auxbuf; | |
204 | struct dentry *dentry = object->dentry; | |
205 | int ret; | |
206 | ||
207 | _enter("%p,#%d", object, auxdata->len); | |
208 | ||
209 | ASSERT(dentry); | |
210 | ASSERT(dentry->d_inode); | |
211 | ||
5f4f9f4a | 212 | auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, cachefiles_gfp); |
9ae326a6 DH |
213 | if (!auxbuf) { |
214 | _leave(" = -ENOMEM"); | |
215 | return -ENOMEM; | |
216 | } | |
217 | ||
218 | /* read the current type label */ | |
219 | ret = vfs_getxattr(dentry, cachefiles_xattr_cache, | |
220 | &auxbuf->type, 512 + 1); | |
221 | if (ret < 0) { | |
222 | if (ret == -ENODATA) | |
223 | goto stale; /* no attribute - power went off | |
224 | * mid-cull? */ | |
225 | ||
226 | if (ret == -ERANGE) | |
227 | goto bad_type_length; | |
228 | ||
229 | cachefiles_io_error_obj(object, | |
230 | "Can't read xattr on %lu (err %d)", | |
231 | dentry->d_inode->i_ino, -ret); | |
232 | goto error; | |
233 | } | |
234 | ||
235 | /* check the on-disk object */ | |
236 | if (ret < 1) | |
237 | goto bad_type_length; | |
238 | ||
239 | if (auxbuf->type != auxdata->type) | |
240 | goto stale; | |
241 | ||
242 | auxbuf->len = ret; | |
243 | ||
244 | /* consult the netfs */ | |
245 | if (object->fscache.cookie->def->check_aux) { | |
246 | enum fscache_checkaux result; | |
247 | unsigned int dlen; | |
248 | ||
249 | dlen = auxbuf->len - 1; | |
250 | ||
251 | _debug("checkaux %s #%u", | |
252 | object->fscache.cookie->def->name, dlen); | |
253 | ||
254 | result = fscache_check_aux(&object->fscache, | |
255 | &auxbuf->data, dlen); | |
256 | ||
257 | switch (result) { | |
258 | /* entry okay as is */ | |
259 | case FSCACHE_CHECKAUX_OKAY: | |
260 | goto okay; | |
261 | ||
262 | /* entry requires update */ | |
263 | case FSCACHE_CHECKAUX_NEEDS_UPDATE: | |
264 | break; | |
265 | ||
266 | /* entry requires deletion */ | |
267 | case FSCACHE_CHECKAUX_OBSOLETE: | |
268 | goto stale; | |
269 | ||
270 | default: | |
271 | BUG(); | |
272 | } | |
273 | ||
274 | /* update the current label */ | |
275 | ret = vfs_setxattr(dentry, cachefiles_xattr_cache, | |
276 | &auxdata->type, auxdata->len, | |
277 | XATTR_REPLACE); | |
278 | if (ret < 0) { | |
279 | cachefiles_io_error_obj(object, | |
280 | "Can't update xattr on %lu" | |
281 | " (error %d)", | |
282 | dentry->d_inode->i_ino, -ret); | |
283 | goto error; | |
284 | } | |
285 | } | |
286 | ||
287 | okay: | |
288 | ret = 0; | |
289 | ||
290 | error: | |
291 | kfree(auxbuf); | |
292 | _leave(" = %d", ret); | |
293 | return ret; | |
294 | ||
295 | bad_type_length: | |
296 | kerror("Cache object %lu xattr length incorrect", | |
297 | dentry->d_inode->i_ino); | |
298 | ret = -EIO; | |
299 | goto error; | |
300 | ||
301 | stale: | |
302 | ret = -ESTALE; | |
303 | goto error; | |
304 | } | |
305 | ||
306 | /* | |
307 | * remove the object's xattr to mark it stale | |
308 | */ | |
309 | int cachefiles_remove_object_xattr(struct cachefiles_cache *cache, | |
310 | struct dentry *dentry) | |
311 | { | |
312 | int ret; | |
313 | ||
314 | ret = vfs_removexattr(dentry, cachefiles_xattr_cache); | |
315 | if (ret < 0) { | |
316 | if (ret == -ENOENT || ret == -ENODATA) | |
317 | ret = 0; | |
318 | else if (ret != -ENOMEM) | |
319 | cachefiles_io_error(cache, | |
320 | "Can't remove xattr from %lu" | |
321 | " (error %d)", | |
322 | dentry->d_inode->i_ino, -ret); | |
323 | } | |
324 | ||
325 | _leave(" = %d", ret); | |
326 | return ret; | |
327 | } |