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 <linux/slab.h>
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 */
cachefiles_check_object_type(struct cachefiles_object * object)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 */
cachefiles_set_object_xattr(struct cachefiles_object * object,struct cachefiles_xattr * auxdata)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
112 ASSERT(object->fscache.cookie);
113 ASSERT(dentry);
114
115 _enter("%p,#%d", object, auxdata->len);
116
117 /* attempt to install the cache metadata directly */
118 _debug("SET %s #%u", object->fscache.cookie->def->name, auxdata->len);
119
120 ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
121 &auxdata->type, auxdata->len,
122 XATTR_CREATE);
123 if (ret < 0 && ret != -ENOMEM)
124 cachefiles_io_error_obj(
125 object,
126 "Failed to set xattr with error %d", ret);
127
128 _leave(" = %d", ret);
129 return ret;
130 }
131
132 /*
133 * update the state xattr on a cache file
134 */
cachefiles_update_object_xattr(struct cachefiles_object * object,struct cachefiles_xattr * auxdata)135 int cachefiles_update_object_xattr(struct cachefiles_object *object,
136 struct cachefiles_xattr *auxdata)
137 {
138 struct dentry *dentry = object->dentry;
139 int ret;
140
141 ASSERT(object->fscache.cookie);
142 ASSERT(dentry);
143
144 _enter("%p,#%d", object, auxdata->len);
145
146 /* attempt to install the cache metadata directly */
147 _debug("SET %s #%u", object->fscache.cookie->def->name, auxdata->len);
148
149 ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
150 &auxdata->type, auxdata->len,
151 XATTR_REPLACE);
152 if (ret < 0 && ret != -ENOMEM)
153 cachefiles_io_error_obj(
154 object,
155 "Failed to update xattr with error %d", ret);
156
157 _leave(" = %d", ret);
158 return ret;
159 }
160
161 /*
162 * check the state xattr on a cache file
163 * - return -ESTALE if the object should be deleted
164 */
cachefiles_check_object_xattr(struct cachefiles_object * object,struct cachefiles_xattr * auxdata)165 int cachefiles_check_object_xattr(struct cachefiles_object *object,
166 struct cachefiles_xattr *auxdata)
167 {
168 struct cachefiles_xattr *auxbuf;
169 struct dentry *dentry = object->dentry;
170 int ret;
171
172 _enter("%p,#%d", object, auxdata->len);
173
174 ASSERT(dentry);
175 ASSERT(dentry->d_inode);
176
177 auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, GFP_KERNEL);
178 if (!auxbuf) {
179 _leave(" = -ENOMEM");
180 return -ENOMEM;
181 }
182
183 /* read the current type label */
184 ret = vfs_getxattr(dentry, cachefiles_xattr_cache,
185 &auxbuf->type, 512 + 1);
186 if (ret < 0) {
187 if (ret == -ENODATA)
188 goto stale; /* no attribute - power went off
189 * mid-cull? */
190
191 if (ret == -ERANGE)
192 goto bad_type_length;
193
194 cachefiles_io_error_obj(object,
195 "Can't read xattr on %lu (err %d)",
196 dentry->d_inode->i_ino, -ret);
197 goto error;
198 }
199
200 /* check the on-disk object */
201 if (ret < 1)
202 goto bad_type_length;
203
204 if (auxbuf->type != auxdata->type)
205 goto stale;
206
207 auxbuf->len = ret;
208
209 /* consult the netfs */
210 if (object->fscache.cookie->def->check_aux) {
211 enum fscache_checkaux result;
212 unsigned int dlen;
213
214 dlen = auxbuf->len - 1;
215
216 _debug("checkaux %s #%u",
217 object->fscache.cookie->def->name, dlen);
218
219 result = fscache_check_aux(&object->fscache,
220 &auxbuf->data, dlen);
221
222 switch (result) {
223 /* entry okay as is */
224 case FSCACHE_CHECKAUX_OKAY:
225 goto okay;
226
227 /* entry requires update */
228 case FSCACHE_CHECKAUX_NEEDS_UPDATE:
229 break;
230
231 /* entry requires deletion */
232 case FSCACHE_CHECKAUX_OBSOLETE:
233 goto stale;
234
235 default:
236 BUG();
237 }
238
239 /* update the current label */
240 ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
241 &auxdata->type, auxdata->len,
242 XATTR_REPLACE);
243 if (ret < 0) {
244 cachefiles_io_error_obj(object,
245 "Can't update xattr on %lu"
246 " (error %d)",
247 dentry->d_inode->i_ino, -ret);
248 goto error;
249 }
250 }
251
252 okay:
253 ret = 0;
254
255 error:
256 kfree(auxbuf);
257 _leave(" = %d", ret);
258 return ret;
259
260 bad_type_length:
261 kerror("Cache object %lu xattr length incorrect",
262 dentry->d_inode->i_ino);
263 ret = -EIO;
264 goto error;
265
266 stale:
267 ret = -ESTALE;
268 goto error;
269 }
270
271 /*
272 * remove the object's xattr to mark it stale
273 */
cachefiles_remove_object_xattr(struct cachefiles_cache * cache,struct dentry * dentry)274 int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,
275 struct dentry *dentry)
276 {
277 int ret;
278
279 ret = vfs_removexattr(dentry, cachefiles_xattr_cache);
280 if (ret < 0) {
281 if (ret == -ENOENT || ret == -ENODATA)
282 ret = 0;
283 else if (ret != -ENOMEM)
284 cachefiles_io_error(cache,
285 "Can't remove xattr from %lu"
286 " (error %d)",
287 dentry->d_inode->i_ino, -ret);
288 }
289
290 _leave(" = %d", ret);
291 return ret;
292 }
293