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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 | 115 | |
402cb8dd | 116 | clear_bit(FSCACHE_COOKIE_AUX_UPDATED, &object->fscache.cookie->flags); |
9ae326a6 DH |
117 | ret = vfs_setxattr(dentry, cachefiles_xattr_cache, |
118 | &auxdata->type, auxdata->len, | |
119 | XATTR_CREATE); | |
120 | if (ret < 0 && ret != -ENOMEM) | |
121 | cachefiles_io_error_obj( | |
122 | object, | |
123 | "Failed to set xattr with error %d", ret); | |
124 | ||
125 | _leave(" = %d", ret); | |
126 | return ret; | |
127 | } | |
128 | ||
129 | /* | |
130 | * update the state xattr on a cache file | |
131 | */ | |
132 | int cachefiles_update_object_xattr(struct cachefiles_object *object, | |
133 | struct cachefiles_xattr *auxdata) | |
134 | { | |
135 | struct dentry *dentry = object->dentry; | |
136 | int ret; | |
137 | ||
e6bc06fa DH |
138 | if (!dentry) |
139 | return -ESTALE; | |
9ae326a6 DH |
140 | |
141 | _enter("%p,#%d", object, auxdata->len); | |
142 | ||
143 | /* attempt to install the cache metadata directly */ | |
1362729b | 144 | _debug("SET #%u", auxdata->len); |
9ae326a6 | 145 | |
402cb8dd | 146 | clear_bit(FSCACHE_COOKIE_AUX_UPDATED, &object->fscache.cookie->flags); |
9ae326a6 DH |
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); | |
466b77bc | 171 | ASSERT(d_backing_inode(dentry)); |
5002d7be DH |
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 | 185 | xlen--; |
ee1235a9 DH |
186 | validity = fscache_check_aux(&object->fscache, &auxbuf->data, xlen, |
187 | i_size_read(d_backing_inode(dentry))); | |
607566ae JB |
188 | if (validity != FSCACHE_CHECKAUX_OKAY) |
189 | goto error; | |
5002d7be | 190 | |
607566ae JB |
191 | ret = 0; |
192 | error: | |
5002d7be | 193 | kfree(auxbuf); |
607566ae | 194 | return ret; |
5002d7be DH |
195 | } |
196 | ||
9ae326a6 DH |
197 | /* |
198 | * check the state xattr on a cache file | |
199 | * - return -ESTALE if the object should be deleted | |
200 | */ | |
201 | int cachefiles_check_object_xattr(struct cachefiles_object *object, | |
202 | struct cachefiles_xattr *auxdata) | |
203 | { | |
204 | struct cachefiles_xattr *auxbuf; | |
205 | struct dentry *dentry = object->dentry; | |
206 | int ret; | |
207 | ||
208 | _enter("%p,#%d", object, auxdata->len); | |
209 | ||
210 | ASSERT(dentry); | |
466b77bc | 211 | ASSERT(d_backing_inode(dentry)); |
9ae326a6 | 212 | |
5f4f9f4a | 213 | auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, cachefiles_gfp); |
9ae326a6 DH |
214 | if (!auxbuf) { |
215 | _leave(" = -ENOMEM"); | |
216 | return -ENOMEM; | |
217 | } | |
218 | ||
219 | /* read the current type label */ | |
220 | ret = vfs_getxattr(dentry, cachefiles_xattr_cache, | |
221 | &auxbuf->type, 512 + 1); | |
222 | if (ret < 0) { | |
223 | if (ret == -ENODATA) | |
224 | goto stale; /* no attribute - power went off | |
225 | * mid-cull? */ | |
226 | ||
227 | if (ret == -ERANGE) | |
228 | goto bad_type_length; | |
229 | ||
230 | cachefiles_io_error_obj(object, | |
231 | "Can't read xattr on %lu (err %d)", | |
466b77bc | 232 | d_backing_inode(dentry)->i_ino, -ret); |
9ae326a6 DH |
233 | goto error; |
234 | } | |
235 | ||
236 | /* check the on-disk object */ | |
237 | if (ret < 1) | |
238 | goto bad_type_length; | |
239 | ||
240 | if (auxbuf->type != auxdata->type) | |
241 | goto stale; | |
242 | ||
243 | auxbuf->len = ret; | |
244 | ||
245 | /* consult the netfs */ | |
246 | if (object->fscache.cookie->def->check_aux) { | |
247 | enum fscache_checkaux result; | |
248 | unsigned int dlen; | |
249 | ||
250 | dlen = auxbuf->len - 1; | |
251 | ||
252 | _debug("checkaux %s #%u", | |
253 | object->fscache.cookie->def->name, dlen); | |
254 | ||
255 | result = fscache_check_aux(&object->fscache, | |
ee1235a9 DH |
256 | &auxbuf->data, dlen, |
257 | i_size_read(d_backing_inode(dentry))); | |
9ae326a6 DH |
258 | |
259 | switch (result) { | |
260 | /* entry okay as is */ | |
261 | case FSCACHE_CHECKAUX_OKAY: | |
262 | goto okay; | |
263 | ||
264 | /* entry requires update */ | |
265 | case FSCACHE_CHECKAUX_NEEDS_UPDATE: | |
266 | break; | |
267 | ||
268 | /* entry requires deletion */ | |
269 | case FSCACHE_CHECKAUX_OBSOLETE: | |
270 | goto stale; | |
271 | ||
272 | default: | |
273 | BUG(); | |
274 | } | |
275 | ||
276 | /* update the current label */ | |
277 | ret = vfs_setxattr(dentry, cachefiles_xattr_cache, | |
278 | &auxdata->type, auxdata->len, | |
279 | XATTR_REPLACE); | |
280 | if (ret < 0) { | |
281 | cachefiles_io_error_obj(object, | |
282 | "Can't update xattr on %lu" | |
283 | " (error %d)", | |
466b77bc | 284 | d_backing_inode(dentry)->i_ino, -ret); |
9ae326a6 DH |
285 | goto error; |
286 | } | |
287 | } | |
288 | ||
289 | okay: | |
290 | ret = 0; | |
291 | ||
292 | error: | |
293 | kfree(auxbuf); | |
294 | _leave(" = %d", ret); | |
295 | return ret; | |
296 | ||
297 | bad_type_length: | |
6ff66ac7 | 298 | pr_err("Cache object %lu xattr length incorrect\n", |
466b77bc | 299 | d_backing_inode(dentry)->i_ino); |
9ae326a6 DH |
300 | ret = -EIO; |
301 | goto error; | |
302 | ||
303 | stale: | |
304 | ret = -ESTALE; | |
305 | goto error; | |
306 | } | |
307 | ||
308 | /* | |
309 | * remove the object's xattr to mark it stale | |
310 | */ | |
311 | int cachefiles_remove_object_xattr(struct cachefiles_cache *cache, | |
312 | struct dentry *dentry) | |
313 | { | |
314 | int ret; | |
315 | ||
316 | ret = vfs_removexattr(dentry, cachefiles_xattr_cache); | |
317 | if (ret < 0) { | |
318 | if (ret == -ENOENT || ret == -ENODATA) | |
319 | ret = 0; | |
320 | else if (ret != -ENOMEM) | |
321 | cachefiles_io_error(cache, | |
322 | "Can't remove xattr from %lu" | |
323 | " (error %d)", | |
466b77bc | 324 | d_backing_inode(dentry)->i_ino, -ret); |
9ae326a6 DH |
325 | } |
326 | ||
327 | _leave(" = %d", ret); | |
328 | return ret; | |
329 | } |