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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 | ||
9ae326a6 DH |
138 | ASSERT(dentry); |
139 | ||
140 | _enter("%p,#%d", object, auxdata->len); | |
141 | ||
142 | /* attempt to install the cache metadata directly */ | |
1362729b | 143 | _debug("SET #%u", auxdata->len); |
9ae326a6 | 144 | |
402cb8dd | 145 | clear_bit(FSCACHE_COOKIE_AUX_UPDATED, &object->fscache.cookie->flags); |
9ae326a6 DH |
146 | ret = vfs_setxattr(dentry, cachefiles_xattr_cache, |
147 | &auxdata->type, auxdata->len, | |
148 | XATTR_REPLACE); | |
149 | if (ret < 0 && ret != -ENOMEM) | |
150 | cachefiles_io_error_obj( | |
151 | object, | |
152 | "Failed to update xattr with error %d", ret); | |
153 | ||
154 | _leave(" = %d", ret); | |
155 | return ret; | |
156 | } | |
157 | ||
5002d7be DH |
158 | /* |
159 | * check the consistency between the backing cache and the FS-Cache cookie | |
160 | */ | |
161 | int cachefiles_check_auxdata(struct cachefiles_object *object) | |
162 | { | |
163 | struct cachefiles_xattr *auxbuf; | |
607566ae | 164 | enum fscache_checkaux validity; |
5002d7be | 165 | struct dentry *dentry = object->dentry; |
607566ae | 166 | ssize_t xlen; |
5002d7be DH |
167 | int ret; |
168 | ||
169 | ASSERT(dentry); | |
466b77bc | 170 | ASSERT(d_backing_inode(dentry)); |
5002d7be DH |
171 | ASSERT(object->fscache.cookie->def->check_aux); |
172 | ||
173 | auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, GFP_KERNEL); | |
174 | if (!auxbuf) | |
175 | return -ENOMEM; | |
176 | ||
607566ae JB |
177 | xlen = vfs_getxattr(dentry, cachefiles_xattr_cache, |
178 | &auxbuf->type, 512 + 1); | |
179 | ret = -ESTALE; | |
180 | if (xlen < 1 || | |
181 | auxbuf->type != object->fscache.cookie->def->type) | |
182 | goto error; | |
5002d7be | 183 | |
607566ae | 184 | xlen--; |
ee1235a9 DH |
185 | validity = fscache_check_aux(&object->fscache, &auxbuf->data, xlen, |
186 | i_size_read(d_backing_inode(dentry))); | |
607566ae JB |
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); | |
466b77bc | 210 | ASSERT(d_backing_inode(dentry)); |
9ae326a6 | 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)", | |
466b77bc | 231 | d_backing_inode(dentry)->i_ino, -ret); |
9ae326a6 DH |
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, | |
ee1235a9 DH |
255 | &auxbuf->data, dlen, |
256 | i_size_read(d_backing_inode(dentry))); | |
9ae326a6 DH |
257 | |
258 | switch (result) { | |
259 | /* entry okay as is */ | |
260 | case FSCACHE_CHECKAUX_OKAY: | |
261 | goto okay; | |
262 | ||
263 | /* entry requires update */ | |
264 | case FSCACHE_CHECKAUX_NEEDS_UPDATE: | |
265 | break; | |
266 | ||
267 | /* entry requires deletion */ | |
268 | case FSCACHE_CHECKAUX_OBSOLETE: | |
269 | goto stale; | |
270 | ||
271 | default: | |
272 | BUG(); | |
273 | } | |
274 | ||
275 | /* update the current label */ | |
276 | ret = vfs_setxattr(dentry, cachefiles_xattr_cache, | |
277 | &auxdata->type, auxdata->len, | |
278 | XATTR_REPLACE); | |
279 | if (ret < 0) { | |
280 | cachefiles_io_error_obj(object, | |
281 | "Can't update xattr on %lu" | |
282 | " (error %d)", | |
466b77bc | 283 | d_backing_inode(dentry)->i_ino, -ret); |
9ae326a6 DH |
284 | goto error; |
285 | } | |
286 | } | |
287 | ||
288 | okay: | |
289 | ret = 0; | |
290 | ||
291 | error: | |
292 | kfree(auxbuf); | |
293 | _leave(" = %d", ret); | |
294 | return ret; | |
295 | ||
296 | bad_type_length: | |
6ff66ac7 | 297 | pr_err("Cache object %lu xattr length incorrect\n", |
466b77bc | 298 | d_backing_inode(dentry)->i_ino); |
9ae326a6 DH |
299 | ret = -EIO; |
300 | goto error; | |
301 | ||
302 | stale: | |
303 | ret = -ESTALE; | |
304 | goto error; | |
305 | } | |
306 | ||
307 | /* | |
308 | * remove the object's xattr to mark it stale | |
309 | */ | |
310 | int cachefiles_remove_object_xattr(struct cachefiles_cache *cache, | |
311 | struct dentry *dentry) | |
312 | { | |
313 | int ret; | |
314 | ||
315 | ret = vfs_removexattr(dentry, cachefiles_xattr_cache); | |
316 | if (ret < 0) { | |
317 | if (ret == -ENOENT || ret == -ENODATA) | |
318 | ret = 0; | |
319 | else if (ret != -ENOMEM) | |
320 | cachefiles_io_error(cache, | |
321 | "Can't remove xattr from %lu" | |
322 | " (error %d)", | |
466b77bc | 323 | d_backing_inode(dentry)->i_ino, -ret); |
9ae326a6 DH |
324 | } |
325 | ||
326 | _leave(" = %d", ret); | |
327 | return ret; | |
328 | } |