[mirror_ubuntu-artful-kernel.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(d_backing_inode(dentry));

	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) {
		pr_err("Can't set xattr on %pd [%lu] (err %d)\n",
		       dentry, d_backing_inode(dentry)->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;

		pr_err("Can't read xattr on %pd [%lu] (err %d)\n",
		       dentry, d_backing_inode(dentry)->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:
	pr_err("Cache object %lu type xattr length incorrect\n",
	       d_backing_inode(dentry)->i_ino);
	ret = -EIO;
	goto error;

bad_type:
	xtype[2] = 0;
	pr_err("Cache object %pd [%lu] type %s not %s\n",
	       dentry, d_backing_inode(dentry)->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;
	enum fscache_checkaux validity;
	struct dentry *dentry = object->dentry;
	ssize_t xlen;
	int ret;

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

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

	xlen = vfs_getxattr(dentry, cachefiles_xattr_cache,
			    &auxbuf->type, 512 + 1);
	ret = -ESTALE;
	if (xlen < 1 ||
	    auxbuf->type != object->fscache.cookie->def->type)
		goto error;

	xlen--;
	validity = fscache_check_aux(&object->fscache, &auxbuf->data, xlen);
	if (validity != FSCACHE_CHECKAUX_OKAY)
		goto error;

	ret = 0;
error:
	kfree(auxbuf);
	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(d_backing_inode(dentry));

	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)",
					d_backing_inode(dentry)->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)",
						d_backing_inode(dentry)->i_ino, -ret);
			goto error;
		}
	}

okay:
	ret = 0;

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

bad_type_length:
	pr_err("Cache object %lu xattr length incorrect\n",
	       d_backing_inode(dentry)->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)",
					    d_backing_inode(dentry)->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);
466b77bc	36	ASSERT(d_backing_inode(dentry));
9ae326a6 DH	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) {
a455589f	54	pr_err("Can't set xattr on %pd [%lu] (err %d)\n",
466b77bc	55	dentry, d_backing_inode(dentry)->i_ino,
9ae326a6 DH	56	-ret);
	57	goto error;
	58	}
	59
	60	/* read the current type label */
	61	ret = vfs_getxattr(dentry, cachefiles_xattr_cache, xtype, 3);
	62	if (ret < 0) {
	63	if (ret == -ERANGE)
	64	goto bad_type_length;
	65
a455589f	66	pr_err("Can't read xattr on %pd [%lu] (err %d)\n",
466b77bc	67	dentry, d_backing_inode(dentry)->i_ino,
9ae326a6 DH	68	-ret);
	69	goto error;
	70	}
	71
	72	/* check the type is what we're expecting */
	73	if (ret != 2)
	74	goto bad_type_length;
	75
	76	if (xtype[0] != type[0] \|\| xtype[1] != type[1])
	77	goto bad_type;
	78
	79	ret = 0;
	80
	81	error:
	82	_leave(" = %d", ret);
	83	return ret;
	84
	85	bad_type_length:
6ff66ac7	86	pr_err("Cache object %lu type xattr length incorrect\n",
466b77bc	87	d_backing_inode(dentry)->i_ino);
9ae326a6 DH	88	ret = -EIO;
	89	goto error;
	90
	91	bad_type:
	92	xtype[2] = 0;
a455589f	93	pr_err("Cache object %pd [%lu] type %s not %s\n",
466b77bc	94	dentry, d_backing_inode(dentry)->i_ino,
9ae326a6 DH	95	xtype, type);
	96	ret = -EIO;
	97	goto error;
	98	}
	99
	100	/*
	101	* set the state xattr on a cache file
	102	*/
	103	int cachefiles_set_object_xattr(struct cachefiles_object *object,
	104	struct cachefiles_xattr *auxdata)
	105	{
	106	struct dentry *dentry = object->dentry;
	107	int ret;
	108
9ae326a6 DH	109	ASSERT(dentry);
	110
	111	_enter("%p,#%d", object, auxdata->len);
	112
	113	/* attempt to install the cache metadata directly */
1362729b	114	_debug("SET #%u", auxdata->len);
9ae326a6 DH	115
	116	ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
	117	&auxdata->type, auxdata->len,
	118	XATTR_CREATE);
	119	if (ret < 0 && ret != -ENOMEM)
	120	cachefiles_io_error_obj(
	121	object,
	122	"Failed to set xattr with error %d", ret);
	123
	124	_leave(" = %d", ret);
	125	return ret;
	126	}
	127
	128	/*
	129	* update the state xattr on a cache file
	130	*/
	131	int cachefiles_update_object_xattr(struct cachefiles_object *object,
	132	struct cachefiles_xattr *auxdata)
	133	{
	134	struct dentry *dentry = object->dentry;
	135	int ret;
	136
9ae326a6 DH	137	ASSERT(dentry);
	138
	139	_enter("%p,#%d", object, auxdata->len);
	140
	141	/* attempt to install the cache metadata directly */
1362729b	142	_debug("SET #%u", auxdata->len);
9ae326a6 DH	143
	144	ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
	145	&auxdata->type, auxdata->len,
	146	XATTR_REPLACE);
	147	if (ret < 0 && ret != -ENOMEM)
	148	cachefiles_io_error_obj(
	149	object,
	150	"Failed to update xattr with error %d", ret);
	151
	152	_leave(" = %d", ret);
	153	return ret;
	154	}
	155
5002d7be DH	156	/*
	157	* check the consistency between the backing cache and the FS-Cache cookie
	158	*/
	159	int cachefiles_check_auxdata(struct cachefiles_object *object)
	160	{
	161	struct cachefiles_xattr *auxbuf;
607566ae	162	enum fscache_checkaux validity;
5002d7be	163	struct dentry *dentry = object->dentry;
607566ae	164	ssize_t xlen;
5002d7be DH	165	int ret;
	166
	167	ASSERT(dentry);
466b77bc	168	ASSERT(d_backing_inode(dentry));
5002d7be DH	169	ASSERT(object->fscache.cookie->def->check_aux);
	170
	171	auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, GFP_KERNEL);
	172	if (!auxbuf)
	173	return -ENOMEM;
	174
607566ae JB	175	xlen = vfs_getxattr(dentry, cachefiles_xattr_cache,
	176	&auxbuf->type, 512 + 1);
	177	ret = -ESTALE;
	178	if (xlen < 1 \|\|
	179	auxbuf->type != object->fscache.cookie->def->type)
	180	goto error;
5002d7be	181
607566ae JB	182	xlen--;
	183	validity = fscache_check_aux(&object->fscache, &auxbuf->data, xlen);
	184	if (validity != FSCACHE_CHECKAUX_OKAY)
	185	goto error;
5002d7be	186
607566ae JB	187	ret = 0;
607566ae JB	188	error:
5002d7be	189	kfree(auxbuf);
607566ae	190	return ret;
5002d7be DH	191	}
5002d7be DH	192
9ae326a6 DH	193	/*
	194	* check the state xattr on a cache file
	195	* - return -ESTALE if the object should be deleted
	196	*/
	197	int cachefiles_check_object_xattr(struct cachefiles_object *object,
	198	struct cachefiles_xattr *auxdata)
	199	{
	200	struct cachefiles_xattr *auxbuf;
	201	struct dentry *dentry = object->dentry;
	202	int ret;
	203
	204	_enter("%p,#%d", object, auxdata->len);
	205
	206	ASSERT(dentry);
466b77bc	207	ASSERT(d_backing_inode(dentry));
9ae326a6	208
5f4f9f4a	209	auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, cachefiles_gfp);
9ae326a6 DH	210	if (!auxbuf) {
	211	_leave(" = -ENOMEM");
	212	return -ENOMEM;
	213	}
	214
	215	/* read the current type label */
	216	ret = vfs_getxattr(dentry, cachefiles_xattr_cache,
	217	&auxbuf->type, 512 + 1);
	218	if (ret < 0) {
	219	if (ret == -ENODATA)
	220	goto stale; /* no attribute - power went off
	221	* mid-cull? */
	222
	223	if (ret == -ERANGE)
	224	goto bad_type_length;
	225
	226	cachefiles_io_error_obj(object,
	227	"Can't read xattr on %lu (err %d)",
466b77bc	228	d_backing_inode(dentry)->i_ino, -ret);
9ae326a6 DH	229	goto error;
	230	}
	231
	232	/* check the on-disk object */
	233	if (ret < 1)
	234	goto bad_type_length;
	235
	236	if (auxbuf->type != auxdata->type)
	237	goto stale;
	238
	239	auxbuf->len = ret;
	240
	241	/* consult the netfs */
	242	if (object->fscache.cookie->def->check_aux) {
	243	enum fscache_checkaux result;
	244	unsigned int dlen;
	245
	246	dlen = auxbuf->len - 1;
	247
	248	_debug("checkaux %s #%u",
	249	object->fscache.cookie->def->name, dlen);
	250
	251	result = fscache_check_aux(&object->fscache,
	252	&auxbuf->data, dlen);
	253
	254	switch (result) {
	255	/* entry okay as is */
	256	case FSCACHE_CHECKAUX_OKAY:
	257	goto okay;
	258
	259	/* entry requires update */
	260	case FSCACHE_CHECKAUX_NEEDS_UPDATE:
	261	break;
	262
	263	/* entry requires deletion */
	264	case FSCACHE_CHECKAUX_OBSOLETE:
	265	goto stale;
	266
	267	default:
	268	BUG();
	269	}
	270
	271	/* update the current label */
	272	ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
	273	&auxdata->type, auxdata->len,
	274	XATTR_REPLACE);
	275	if (ret < 0) {
	276	cachefiles_io_error_obj(object,
	277	"Can't update xattr on %lu"
	278	" (error %d)",
466b77bc	279	d_backing_inode(dentry)->i_ino, -ret);
9ae326a6 DH	280	goto error;
	281	}
	282	}
	283
	284	okay:
	285	ret = 0;
	286
	287	error:
	288	kfree(auxbuf);
	289	_leave(" = %d", ret);
	290	return ret;
	291
	292	bad_type_length:
6ff66ac7	293	pr_err("Cache object %lu xattr length incorrect\n",
466b77bc	294	d_backing_inode(dentry)->i_ino);
9ae326a6 DH	295	ret = -EIO;
	296	goto error;
	297
	298	stale:
	299	ret = -ESTALE;
	300	goto error;
	301	}
	302
	303	/*
	304	* remove the object's xattr to mark it stale
	305	*/
	306	int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,
	307	struct dentry *dentry)
	308	{
	309	int ret;
	310
	311	ret = vfs_removexattr(dentry, cachefiles_xattr_cache);
	312	if (ret < 0) {
	313	if (ret == -ENOENT \|\| ret == -ENODATA)
	314	ret = 0;
	315	else if (ret != -ENOMEM)
	316	cachefiles_io_error(cache,
	317	"Can't remove xattr from %lu"
	318	" (error %d)",
466b77bc	319	d_backing_inode(dentry)->i_ino, -ret);
9ae326a6 DH	320	}
	321
	322	_leave(" = %d", ret);
	323	return ret;
	324	}