aboutsummaryrefslogtreecommitdiff
path: root/fs/cachefiles/xattr.c
blob: 34c88b83e39f1214b0ed7f2c22bc58f5acd00fa4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
/* CacheFiles extended attribute management
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/fsnotify.h>
#include <linux/quotaops.h>
#include <linux/xattr.h>
#include <linux/slab.h>
#include "internal.h"

static const char cachefiles_xattr_cache[] =
	XATTR_USER_PREFIX "CacheFiles.cache";

/*
 * check the type label on an object
 * - done using xattrs
 */
int cachefiles_check_object_type(struct cachefiles_object *object)
{
	struct dentry *dentry = object->dentry;
	char type[3], xtype[3];
	int ret;

	ASSERT(dentry);
	ASSERT(dentry->d_inode);

	if (!object->fscache.cookie)
		strcpy(type, "C3");
	else
		snprintf(type, 3, "%02x", object->fscache.cookie->def->type);

	_enter("%p{%s}", object, type);

	/* attempt to install a type label directly */
	ret = vfs_setxattr(dentry, cachefiles_xattr_cache, type, 2,
			   XATTR_CREATE);
	if (ret == 0) {
		_debug("SET"); /* we succeeded */
		goto error;
	}

	if (ret != -EEXIST) {
		kerror("Can't set xattr on %*.*s [%lu] (err %d)",
		       dentry->d_name.len, dentry->d_name.len,
		       dentry->d_name.name, dentry->d_inode->i_ino,
		       -ret);
		goto error;
	}

	/* read the current type label */
	ret = vfs_getxattr(dentry, cachefiles_xattr_cache, xtype, 3);
	if (ret < 0) {
		if (ret == -ERANGE)
			goto bad_type_length;

		kerror("Can't read xattr on %*.*s [%lu] (err %d)",
		       dentry->d_name.len, dentry->d_name.len,
		       dentry->d_name.name, dentry->d_inode->i_ino,
		       -ret);
		goto error;
	}

	/* check the type is what we're expecting */
	if (ret != 2)
		goto bad_type_length;

	if (xtype[0] != type[0] || xtype[1] != type[1])
		goto bad_type;

	ret = 0;

error:
	_leave(" = %d", ret);
	return ret;

bad_type_length:
	kerror("Cache object %lu type xattr length incorrect",
	       dentry->d_inode->i_ino);
	ret = -EIO;
	goto error;

bad_type:
	xtype[2] = 0;
	kerror("Cache object %*.*s [%lu] type %s not %s",
	       dentry->d_name.len, dentry->d_name.len,
	       dentry->d_name.name, dentry->d_inode->i_ino,
	       xtype, type);
	ret = -EIO;
	goto error;
}

/*
 * set the state xattr on a cache file
 */
int cachefiles_set_object_xattr(struct cachefiles_object *object,
				struct cachefiles_xattr *auxdata)
{
	struct dentry *dentry = object->dentry;
	int ret;

	ASSERT(dentry);

	_enter("%p,#%d", object, auxdata->len);

	/* attempt to install the cache metadata directly */
	_debug("SET #%u", auxdata->len);

	ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
			   &auxdata->type, auxdata->len,
			   XATTR_CREATE);
	if (ret < 0 && ret != -ENOMEM)
		cachefiles_io_error_obj(
			object,
			"Failed to set xattr with error %d", ret);

	_leave(" = %d", ret);
	return ret;
}

/*
 * update the state xattr on a cache file
 */
int cachefiles_update_object_xattr(struct cachefiles_object *object,
				   struct cachefiles_xattr *auxdata)
{
	struct dentry *dentry = object->dentry;
	int ret;

	ASSERT(dentry);

	_enter("%p,#%d", object, auxdata->len);

	/* attempt to install the cache metadata directly */
	_debug("SET #%u", auxdata->len);

	ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
			   &auxdata->type, auxdata->len,
			   XATTR_REPLACE);
	if (ret < 0 && ret != -ENOMEM)
		cachefiles_io_error_obj(
			object,
			"Failed to update xattr with error %d", ret);

	_leave(" = %d", ret);
	return ret;
}

/*
 * check the consistency between the backing cache and the FS-Cache cookie
 */
int cachefiles_check_auxdata(struct cachefiles_object *object)
{
	struct cachefiles_xattr *auxbuf;
	struct dentry *dentry = object->dentry;
	unsigned int dlen;
	int ret;

	ASSERT(dentry);
	ASSERT(dentry->d_inode);
	ASSERT(object->fscache.cookie->def->check_aux);

	auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, GFP_KERNEL);
	if (!auxbuf)
		return -ENOMEM;

	auxbuf->len = vfs_getxattr(dentry, cachefiles_xattr_cache,
				   &auxbuf->type, 512 + 1);
	if (auxbuf->len < 1)
		return -ESTALE;

	if (auxbuf->type != object->fscache.cookie->def->type)
		return -ESTALE;

	dlen = auxbuf->len - 1;
	ret = fscache_check_aux(&object->fscache, &auxbuf->data, dlen);

	kfree(auxbuf);
	if (ret != FSCACHE_CHECKAUX_OKAY)
		return -ESTALE;

	return 0;
}

/*
 * check the state xattr on a cache file
 * - return -ESTALE if the object should be deleted
 */
int cachefiles_check_object_xattr(struct cachefiles_object *object,
				  struct cachefiles_xattr *auxdata)
{
	struct cachefiles_xattr *auxbuf;
	struct dentry *dentry = object->dentry;
	int ret;

	_enter("%p,#%d", object, auxdata->len);

	ASSERT(dentry);
	ASSERT(dentry->d_inode);

	auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, cachefiles_gfp);
	if (!auxbuf) {
		_leave(" = -ENOMEM");
		return -ENOMEM;
	}

	/* read the current type label */
	ret = vfs_getxattr(dentry, cachefiles_xattr_cache,
			   &auxbuf->type, 512 + 1);
	if (ret < 0) {
		if (ret == -ENODATA)
			goto stale; /* no attribute - power went off
				     * mid-cull? */

		if (ret == -ERANGE)
			goto bad_type_length;

		cachefiles_io_error_obj(object,
					"Can't read xattr on %lu (err %d)",
					dentry->d_inode->i_ino, -ret);
		goto error;
	}

	/* check the on-disk object */
	if (ret < 1)
		goto bad_type_length;

	if (auxbuf->type != auxdata->type)
		goto stale;

	auxbuf->len = ret;

	/* consult the netfs */
	if (object->fscache.cookie->def->check_aux) {
		enum fscache_checkaux result;
		unsigned int dlen;

		dlen = auxbuf->len - 1;

		_debug("checkaux %s #%u",
		       object->fscache.cookie->def->name, dlen);

		result = fscache_check_aux(&object->fscache,
					   &auxbuf->data, dlen);

		switch (result) {
			/* entry okay as is */
		case FSCACHE_CHECKAUX_OKAY:
			goto okay;

			/* entry requires update */
		case FSCACHE_CHECKAUX_NEEDS_UPDATE:
			break;

			/* entry requires deletion */
		case FSCACHE_CHECKAUX_OBSOLETE:
			goto stale;

		default:
			BUG();
		}

		/* update the current label */
		ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
				   &auxdata->type, auxdata->len,
				   XATTR_REPLACE);
		if (ret < 0) {
			cachefiles_io_error_obj(object,
						"Can't update xattr on %lu"
						" (error %d)",
						dentry->d_inode->i_ino, -ret);
			goto error;
		}
	}

okay:
	ret = 0;

error:
	kfree(auxbuf);
	_leave(" = %d", ret);
	return ret;

bad_type_length:
	kerror("Cache object %lu xattr length incorrect",
	       dentry->d_inode->i_ino);
	ret = -EIO;
	goto error;

stale:
	ret = -ESTALE;
	goto error;
}

/*
 * remove the object's xattr to mark it stale
 */
int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,
				   struct dentry *dentry)
{
	int ret;

	ret = vfs_removexattr(dentry, cachefiles_xattr_cache);
	if (ret < 0) {
		if (ret == -ENOENT || ret == -ENODATA)
			ret = 0;
		else if (ret != -ENOMEM)
			cachefiles_io_error(cache,
					    "Can't remove xattr from %lu"
					    " (error %d)",
					    dentry->d_inode->i_ino, -ret);
	}

	_leave(" = %d", ret);
	return ret;
}