summaryrefslogtreecommitdiff
path: root/fs/cachefiles/xattr.c
blob: 00b087c14995a0be7d407efa1f40f620a1acb7f3 (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
// SPDX-License-Identifier: GPL-2.0-or-later
/* CacheFiles extended attribute management
 *
 * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#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"

#define CACHEFILES_COOKIE_TYPE_DATA 1

struct cachefiles_xattr {
	__be64	object_size;	/* Actual size of the object */
	__be64	zero_point;	/* Size after which server has no data not written by us */
	__u8	type;		/* Type of object */
	__u8	content;	/* Content presence (enum cachefiles_content) */
	__u8	data[];		/* netfs coherency data */
} __packed;

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

struct cachefiles_vol_xattr {
	__be32	reserved;	/* Reserved, should be 0 */
	__u8	data[];		/* netfs volume coherency data */
} __packed;

/*
 * set the state xattr on a cache file
 */
int cachefiles_set_object_xattr(struct cachefiles_object *object)
{
	struct cachefiles_xattr *buf;
	struct dentry *dentry;
	struct file *file = object->file;
	unsigned int len = object->cookie->aux_len;
	int ret;

	if (!file)
		return -ESTALE;
	dentry = file->f_path.dentry;

	_enter("%x,#%d", object->debug_id, len);

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

	buf->object_size	= cpu_to_be64(object->cookie->object_size);
	buf->zero_point		= 0;
	buf->type		= CACHEFILES_COOKIE_TYPE_DATA;
	buf->content		= object->content_info;
	if (test_bit(FSCACHE_COOKIE_LOCAL_WRITE, &object->cookie->flags))
		buf->content	= CACHEFILES_CONTENT_DIRTY;
	if (len > 0)
		memcpy(buf->data, fscache_get_aux(object->cookie), len);

	ret = cachefiles_inject_write_error();
	if (ret == 0)
		ret = vfs_setxattr(&init_user_ns, dentry, cachefiles_xattr_cache,
				   buf, sizeof(struct cachefiles_xattr) + len, 0);
	if (ret < 0) {
		trace_cachefiles_vfs_error(object, file_inode(file), ret,
					   cachefiles_trace_setxattr_error);
		trace_cachefiles_coherency(object, file_inode(file)->i_ino,
					   buf->content,
					   cachefiles_coherency_set_fail);
		if (ret != -ENOMEM)
			cachefiles_io_error_obj(
				object,
				"Failed to set xattr with error %d", ret);
	} else {
		trace_cachefiles_coherency(object, file_inode(file)->i_ino,
					   buf->content,
					   cachefiles_coherency_set_ok);
	}

	kfree(buf);
	_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 file *file)
{
	struct cachefiles_xattr *buf;
	struct dentry *dentry = file->f_path.dentry;
	unsigned int len = object->cookie->aux_len, tlen;
	const void *p = fscache_get_aux(object->cookie);
	enum cachefiles_coherency_trace why;
	ssize_t xlen;
	int ret = -ESTALE;

	tlen = sizeof(struct cachefiles_xattr) + len;
	buf = kmalloc(tlen, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	xlen = cachefiles_inject_read_error();
	if (xlen == 0)
		xlen = vfs_getxattr(&init_user_ns, dentry, cachefiles_xattr_cache, buf, tlen);
	if (xlen != tlen) {
		if (xlen < 0)
			trace_cachefiles_vfs_error(object, file_inode(file), xlen,
						   cachefiles_trace_getxattr_error);
		if (xlen == -EIO)
			cachefiles_io_error_obj(
				object,
				"Failed to read aux with error %zd", xlen);
		why = cachefiles_coherency_check_xattr;
	} else if (buf->type != CACHEFILES_COOKIE_TYPE_DATA) {
		why = cachefiles_coherency_check_type;
	} else if (memcmp(buf->data, p, len) != 0) {
		why = cachefiles_coherency_check_aux;
	} else if (be64_to_cpu(buf->object_size) != object->cookie->object_size) {
		why = cachefiles_coherency_check_objsize;
	} else if (buf->content == CACHEFILES_CONTENT_DIRTY) {
		// TODO: Begin conflict resolution
		pr_warn("Dirty object in cache\n");
		why = cachefiles_coherency_check_dirty;
	} else {
		why = cachefiles_coherency_check_ok;
		ret = 0;
	}

	trace_cachefiles_coherency(object, file_inode(file)->i_ino,
				   buf->content, why);
	kfree(buf);
	return ret;
}

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

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

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

/*
 * Stick a marker on the cache object to indicate that it's dirty.
 */
void cachefiles_prepare_to_write(struct fscache_cookie *cookie)
{
	const struct cred *saved_cred;
	struct cachefiles_object *object = cookie->cache_priv;
	struct cachefiles_cache *cache = object->volume->cache;

	_enter("c=%08x", object->cookie->debug_id);

	if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) {
		cachefiles_begin_secure(cache, &saved_cred);
		cachefiles_set_object_xattr(object);
		cachefiles_end_secure(cache, saved_cred);
	}
}

/*
 * Set the state xattr on a volume directory.
 */
bool cachefiles_set_volume_xattr(struct cachefiles_volume *volume)
{
	struct cachefiles_vol_xattr *buf;
	unsigned int len = volume->vcookie->coherency_len;
	const void *p = volume->vcookie->coherency;
	struct dentry *dentry = volume->dentry;
	int ret;

	_enter("%x,#%d", volume->vcookie->debug_id, len);

	len += sizeof(*buf);
	buf = kmalloc(len, GFP_KERNEL);
	if (!buf)
		return false;
	buf->reserved = cpu_to_be32(0);
	memcpy(buf->data, p, volume->vcookie->coherency_len);

	ret = cachefiles_inject_write_error();
	if (ret == 0)
		ret = vfs_setxattr(&init_user_ns, dentry, cachefiles_xattr_cache,
				   buf, len, 0);
	if (ret < 0) {
		trace_cachefiles_vfs_error(NULL, d_inode(dentry), ret,
					   cachefiles_trace_setxattr_error);
		trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino,
					       cachefiles_coherency_vol_set_fail);
		if (ret != -ENOMEM)
			cachefiles_io_error(
				volume->cache, "Failed to set xattr with error %d", ret);
	} else {
		trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino,
					       cachefiles_coherency_vol_set_ok);
	}

	kfree(buf);
	_leave(" = %d", ret);
	return ret == 0;
}

/*
 * Check the consistency between the backing cache and the volume cookie.
 */
int cachefiles_check_volume_xattr(struct cachefiles_volume *volume)
{
	struct cachefiles_vol_xattr *buf;
	struct dentry *dentry = volume->dentry;
	unsigned int len = volume->vcookie->coherency_len;
	const void *p = volume->vcookie->coherency;
	enum cachefiles_coherency_trace why;
	ssize_t xlen;
	int ret = -ESTALE;

	_enter("");

	len += sizeof(*buf);
	buf = kmalloc(len, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	xlen = cachefiles_inject_read_error();
	if (xlen == 0)
		xlen = vfs_getxattr(&init_user_ns, dentry, cachefiles_xattr_cache, buf, len);
	if (xlen != len) {
		if (xlen < 0) {
			trace_cachefiles_vfs_error(NULL, d_inode(dentry), xlen,
						   cachefiles_trace_getxattr_error);
			if (xlen == -EIO)
				cachefiles_io_error(
					volume->cache,
					"Failed to read xattr with error %zd", xlen);
		}
		why = cachefiles_coherency_vol_check_xattr;
	} else if (buf->reserved != cpu_to_be32(0)) {
		why = cachefiles_coherency_vol_check_resv;
	} else if (memcmp(buf->data, p, len - sizeof(*buf)) != 0) {
		why = cachefiles_coherency_vol_check_cmp;
	} else {
		why = cachefiles_coherency_vol_check_ok;
		ret = 0;
	}

	trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino, why);
	kfree(buf);
	_leave(" = %d", ret);
	return ret;
}