[linux.git] / fs / cachefiles / xattr.c

/* CacheFiles extended attribute management
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * 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(object->fscache.cookie);
	ASSERT(dentry);

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

	/* attempt to install the cache metadata directly */
	_debug("SET %s #%u", object->fscache.cookie->def->name, 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(object->fscache.cookie);
	ASSERT(dentry);

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

	/* attempt to install the cache metadata directly */
	_debug("SET %s #%u", object->fscache.cookie->def->name, 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 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, GFP_KERNEL);
	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;
}
Commit	Line	Data
9ae326a6 DH	1	/* CacheFiles extended attribute management
	2	*
	3	* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells ([email protected])
	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);
	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	*/
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	*/
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	*/
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	*/
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	}