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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); | |
466b77bc | 36 | ASSERT(d_backing_inode(dentry)); |
9ae326a6 DH |
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) { | |
a455589f | 54 | pr_err("Can't set xattr on %pd [%lu] (err %d)\n", |
466b77bc | 55 | dentry, d_backing_inode(dentry)->i_ino, |
9ae326a6 DH |
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 | ||
a455589f | 66 | pr_err("Can't read xattr on %pd [%lu] (err %d)\n", |
466b77bc | 67 | dentry, d_backing_inode(dentry)->i_ino, |
9ae326a6 DH |
68 | -ret); |
69 | goto error; | |
70 | } | |
71 | ||
72 | /* check the type is what we're expecting */ | |
73 | if (ret != 2) | |
74 | goto bad_type_length; | |
75 | ||
76 | if (xtype[0] != type[0] || xtype[1] != type[1]) | |
77 | goto bad_type; | |
78 | ||
79 | ret = 0; | |
80 | ||
81 | error: | |
82 | _leave(" = %d", ret); | |
83 | return ret; | |
84 | ||
85 | bad_type_length: | |
6ff66ac7 | 86 | pr_err("Cache object %lu type xattr length incorrect\n", |
466b77bc | 87 | d_backing_inode(dentry)->i_ino); |
9ae326a6 DH |
88 | ret = -EIO; |
89 | goto error; | |
90 | ||
91 | bad_type: | |
92 | xtype[2] = 0; | |
a455589f | 93 | pr_err("Cache object %pd [%lu] type %s not %s\n", |
466b77bc | 94 | dentry, d_backing_inode(dentry)->i_ino, |
9ae326a6 DH |
95 | xtype, type); |
96 | ret = -EIO; | |
97 | goto error; | |
98 | } | |
99 | ||
100 | /* | |
101 | * set the state xattr on a cache file | |
102 | */ | |
103 | int cachefiles_set_object_xattr(struct cachefiles_object *object, | |
104 | struct cachefiles_xattr *auxdata) | |
105 | { | |
106 | struct dentry *dentry = object->dentry; | |
107 | int ret; | |
108 | ||
9ae326a6 DH |
109 | ASSERT(dentry); |
110 | ||
111 | _enter("%p,#%d", object, auxdata->len); | |
112 | ||
113 | /* attempt to install the cache metadata directly */ | |
1362729b | 114 | _debug("SET #%u", auxdata->len); |
9ae326a6 DH |
115 | |
116 | ret = vfs_setxattr(dentry, cachefiles_xattr_cache, | |
117 | &auxdata->type, auxdata->len, | |
118 | XATTR_CREATE); | |
119 | if (ret < 0 && ret != -ENOMEM) | |
120 | cachefiles_io_error_obj( | |
121 | object, | |
122 | "Failed to set xattr with error %d", ret); | |
123 | ||
124 | _leave(" = %d", ret); | |
125 | return ret; | |
126 | } | |
127 | ||
128 | /* | |
129 | * update the state xattr on a cache file | |
130 | */ | |
131 | int cachefiles_update_object_xattr(struct cachefiles_object *object, | |
132 | struct cachefiles_xattr *auxdata) | |
133 | { | |
134 | struct dentry *dentry = object->dentry; | |
135 | int ret; | |
136 | ||
9ae326a6 DH |
137 | ASSERT(dentry); |
138 | ||
139 | _enter("%p,#%d", object, auxdata->len); | |
140 | ||
141 | /* attempt to install the cache metadata directly */ | |
1362729b | 142 | _debug("SET #%u", auxdata->len); |
9ae326a6 DH |
143 | |
144 | ret = vfs_setxattr(dentry, cachefiles_xattr_cache, | |
145 | &auxdata->type, auxdata->len, | |
146 | XATTR_REPLACE); | |
147 | if (ret < 0 && ret != -ENOMEM) | |
148 | cachefiles_io_error_obj( | |
149 | object, | |
150 | "Failed to update xattr with error %d", ret); | |
151 | ||
152 | _leave(" = %d", ret); | |
153 | return ret; | |
154 | } | |
155 | ||
5002d7be DH |
156 | /* |
157 | * check the consistency between the backing cache and the FS-Cache cookie | |
158 | */ | |
159 | int cachefiles_check_auxdata(struct cachefiles_object *object) | |
160 | { | |
161 | struct cachefiles_xattr *auxbuf; | |
607566ae | 162 | enum fscache_checkaux validity; |
5002d7be | 163 | struct dentry *dentry = object->dentry; |
607566ae | 164 | ssize_t xlen; |
5002d7be DH |
165 | int ret; |
166 | ||
167 | ASSERT(dentry); | |
466b77bc | 168 | ASSERT(d_backing_inode(dentry)); |
5002d7be DH |
169 | ASSERT(object->fscache.cookie->def->check_aux); |
170 | ||
171 | auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, GFP_KERNEL); | |
172 | if (!auxbuf) | |
173 | return -ENOMEM; | |
174 | ||
607566ae JB |
175 | xlen = vfs_getxattr(dentry, cachefiles_xattr_cache, |
176 | &auxbuf->type, 512 + 1); | |
177 | ret = -ESTALE; | |
178 | if (xlen < 1 || | |
179 | auxbuf->type != object->fscache.cookie->def->type) | |
180 | goto error; | |
5002d7be | 181 | |
607566ae JB |
182 | xlen--; |
183 | validity = fscache_check_aux(&object->fscache, &auxbuf->data, xlen); | |
184 | if (validity != FSCACHE_CHECKAUX_OKAY) | |
185 | goto error; | |
5002d7be | 186 | |
607566ae JB |
187 | ret = 0; |
188 | error: | |
5002d7be | 189 | kfree(auxbuf); |
607566ae | 190 | return ret; |
5002d7be DH |
191 | } |
192 | ||
9ae326a6 DH |
193 | /* |
194 | * check the state xattr on a cache file | |
195 | * - return -ESTALE if the object should be deleted | |
196 | */ | |
197 | int cachefiles_check_object_xattr(struct cachefiles_object *object, | |
198 | struct cachefiles_xattr *auxdata) | |
199 | { | |
200 | struct cachefiles_xattr *auxbuf; | |
201 | struct dentry *dentry = object->dentry; | |
202 | int ret; | |
203 | ||
204 | _enter("%p,#%d", object, auxdata->len); | |
205 | ||
206 | ASSERT(dentry); | |
466b77bc | 207 | ASSERT(d_backing_inode(dentry)); |
9ae326a6 | 208 | |
5f4f9f4a | 209 | auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, cachefiles_gfp); |
9ae326a6 DH |
210 | if (!auxbuf) { |
211 | _leave(" = -ENOMEM"); | |
212 | return -ENOMEM; | |
213 | } | |
214 | ||
215 | /* read the current type label */ | |
216 | ret = vfs_getxattr(dentry, cachefiles_xattr_cache, | |
217 | &auxbuf->type, 512 + 1); | |
218 | if (ret < 0) { | |
219 | if (ret == -ENODATA) | |
220 | goto stale; /* no attribute - power went off | |
221 | * mid-cull? */ | |
222 | ||
223 | if (ret == -ERANGE) | |
224 | goto bad_type_length; | |
225 | ||
226 | cachefiles_io_error_obj(object, | |
227 | "Can't read xattr on %lu (err %d)", | |
466b77bc | 228 | d_backing_inode(dentry)->i_ino, -ret); |
9ae326a6 DH |
229 | goto error; |
230 | } | |
231 | ||
232 | /* check the on-disk object */ | |
233 | if (ret < 1) | |
234 | goto bad_type_length; | |
235 | ||
236 | if (auxbuf->type != auxdata->type) | |
237 | goto stale; | |
238 | ||
239 | auxbuf->len = ret; | |
240 | ||
241 | /* consult the netfs */ | |
242 | if (object->fscache.cookie->def->check_aux) { | |
243 | enum fscache_checkaux result; | |
244 | unsigned int dlen; | |
245 | ||
246 | dlen = auxbuf->len - 1; | |
247 | ||
248 | _debug("checkaux %s #%u", | |
249 | object->fscache.cookie->def->name, dlen); | |
250 | ||
251 | result = fscache_check_aux(&object->fscache, | |
252 | &auxbuf->data, dlen); | |
253 | ||
254 | switch (result) { | |
255 | /* entry okay as is */ | |
256 | case FSCACHE_CHECKAUX_OKAY: | |
257 | goto okay; | |
258 | ||
259 | /* entry requires update */ | |
260 | case FSCACHE_CHECKAUX_NEEDS_UPDATE: | |
261 | break; | |
262 | ||
263 | /* entry requires deletion */ | |
264 | case FSCACHE_CHECKAUX_OBSOLETE: | |
265 | goto stale; | |
266 | ||
267 | default: | |
268 | BUG(); | |
269 | } | |
270 | ||
271 | /* update the current label */ | |
272 | ret = vfs_setxattr(dentry, cachefiles_xattr_cache, | |
273 | &auxdata->type, auxdata->len, | |
274 | XATTR_REPLACE); | |
275 | if (ret < 0) { | |
276 | cachefiles_io_error_obj(object, | |
277 | "Can't update xattr on %lu" | |
278 | " (error %d)", | |
466b77bc | 279 | d_backing_inode(dentry)->i_ino, -ret); |
9ae326a6 DH |
280 | goto error; |
281 | } | |
282 | } | |
283 | ||
284 | okay: | |
285 | ret = 0; | |
286 | ||
287 | error: | |
288 | kfree(auxbuf); | |
289 | _leave(" = %d", ret); | |
290 | return ret; | |
291 | ||
292 | bad_type_length: | |
6ff66ac7 | 293 | pr_err("Cache object %lu xattr length incorrect\n", |
466b77bc | 294 | d_backing_inode(dentry)->i_ino); |
9ae326a6 DH |
295 | ret = -EIO; |
296 | goto error; | |
297 | ||
298 | stale: | |
299 | ret = -ESTALE; | |
300 | goto error; | |
301 | } | |
302 | ||
303 | /* | |
304 | * remove the object's xattr to mark it stale | |
305 | */ | |
306 | int cachefiles_remove_object_xattr(struct cachefiles_cache *cache, | |
307 | struct dentry *dentry) | |
308 | { | |
309 | int ret; | |
310 | ||
311 | ret = vfs_removexattr(dentry, cachefiles_xattr_cache); | |
312 | if (ret < 0) { | |
313 | if (ret == -ENOENT || ret == -ENODATA) | |
314 | ret = 0; | |
315 | else if (ret != -ENOMEM) | |
316 | cachefiles_io_error(cache, | |
317 | "Can't remove xattr from %lu" | |
318 | " (error %d)", | |
466b77bc | 319 | d_backing_inode(dentry)->i_ino, -ret); |
9ae326a6 DH |
320 | } |
321 | ||
322 | _leave(" = %d", ret); | |
323 | return ret; | |
324 | } |