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

/* 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 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;
}
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 (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);
	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
9ae326a6 DH	112	ASSERT(dentry);
	113
	114	_enter("%p,#%d", object, auxdata->len);
	115
	116	/* attempt to install the cache metadata directly */
1362729b	117	_debug("SET #%u", auxdata->len);
9ae326a6 DH	118
	119	ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
	120	&auxdata->type, auxdata->len,
	121	XATTR_CREATE);
	122	if (ret < 0 && ret != -ENOMEM)
	123	cachefiles_io_error_obj(
	124	object,
	125	"Failed to set xattr with error %d", ret);
	126
	127	_leave(" = %d", ret);
	128	return ret;
	129	}
	130
	131	/*
	132	* update the state xattr on a cache file
	133	*/
	134	int cachefiles_update_object_xattr(struct cachefiles_object *object,
	135	struct cachefiles_xattr *auxdata)
	136	{
	137	struct dentry *dentry = object->dentry;
	138	int ret;
	139
9ae326a6 DH	140	ASSERT(dentry);
	141
	142	_enter("%p,#%d", object, auxdata->len);
	143
	144	/* attempt to install the cache metadata directly */
1362729b	145	_debug("SET #%u", auxdata->len);
9ae326a6 DH	146
	147	ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
	148	&auxdata->type, auxdata->len,
	149	XATTR_REPLACE);
	150	if (ret < 0 && ret != -ENOMEM)
	151	cachefiles_io_error_obj(
	152	object,
	153	"Failed to update xattr with error %d", ret);
	154
	155	_leave(" = %d", ret);
	156	return ret;
	157	}
	158
	159	/*
	160	* check the state xattr on a cache file
	161	* - return -ESTALE if the object should be deleted
	162	*/
	163	int cachefiles_check_object_xattr(struct cachefiles_object *object,
	164	struct cachefiles_xattr *auxdata)
	165	{
	166	struct cachefiles_xattr *auxbuf;
	167	struct dentry *dentry = object->dentry;
	168	int ret;
	169
	170	_enter("%p,#%d", object, auxdata->len);
	171
	172	ASSERT(dentry);
	173	ASSERT(dentry->d_inode);
	174
5f4f9f4a	175	auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, cachefiles_gfp);
9ae326a6 DH	176	if (!auxbuf) {
	177	_leave(" = -ENOMEM");
	178	return -ENOMEM;
	179	}
	180
	181	/* read the current type label */
	182	ret = vfs_getxattr(dentry, cachefiles_xattr_cache,
	183	&auxbuf->type, 512 + 1);
	184	if (ret < 0) {
	185	if (ret == -ENODATA)
	186	goto stale; /* no attribute - power went off
	187	* mid-cull? */
	188
	189	if (ret == -ERANGE)
	190	goto bad_type_length;
	191
	192	cachefiles_io_error_obj(object,
	193	"Can't read xattr on %lu (err %d)",
	194	dentry->d_inode->i_ino, -ret);
	195	goto error;
	196	}
	197
	198	/* check the on-disk object */
	199	if (ret < 1)
	200	goto bad_type_length;
	201
	202	if (auxbuf->type != auxdata->type)
	203	goto stale;
	204
	205	auxbuf->len = ret;
	206
	207	/* consult the netfs */
	208	if (object->fscache.cookie->def->check_aux) {
	209	enum fscache_checkaux result;
	210	unsigned int dlen;
	211
	212	dlen = auxbuf->len - 1;
	213
	214	_debug("checkaux %s #%u",
	215	object->fscache.cookie->def->name, dlen);
	216
	217	result = fscache_check_aux(&object->fscache,
	218	&auxbuf->data, dlen);
	219
	220	switch (result) {
	221	/* entry okay as is */
	222	case FSCACHE_CHECKAUX_OKAY:
	223	goto okay;
	224
	225	/* entry requires update */
	226	case FSCACHE_CHECKAUX_NEEDS_UPDATE:
	227	break;
	228
	229	/* entry requires deletion */
	230	case FSCACHE_CHECKAUX_OBSOLETE:
	231	goto stale;
	232
	233	default:
	234	BUG();
	235	}
	236
	237	/* update the current label */
	238	ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
	239	&auxdata->type, auxdata->len,
240	XATTR_REPLACE);
241	if (ret < 0) {
242	cachefiles_io_error_obj(object,
243	"Can't update xattr on %lu"
244	" (error %d)",
245	dentry->d_inode->i_ino, -ret);
246	goto error;
247	}
248	}
249
250	okay:
251	ret = 0;
252
253	error:
254	kfree(auxbuf);
255	_leave(" = %d", ret);
256	return ret;
257
258	bad_type_length:
259	kerror("Cache object %lu xattr length incorrect",
260	dentry->d_inode->i_ino);
261	ret = -EIO;
262	goto error;
263
264	stale:
265	ret = -ESTALE;
266	goto error;
267	}
268
269	/*
270	* remove the object's xattr to mark it stale
271	*/
272	int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,
273	struct dentry *dentry)
274	{
275	int ret;
276
277	ret = vfs_removexattr(dentry, cachefiles_xattr_cache);
278	if (ret < 0) {
279	if (ret == -ENOENT \|\| ret == -ENODATA)
280	ret = 0;
281	else if (ret != -ENOMEM)
282	cachefiles_io_error(cache,
283	"Can't remove xattr from %lu"
284	" (error %d)",
285	dentry->d_inode->i_ino, -ret);
286	}
287
288	_leave(" = %d", ret);
289	return ret;
290	}