fs/btrfs/xattr.c - kernel/msm-4.19 - Gitiles

 /*
  * Copyright (C) 2007 Red Hat.  All rights reserved.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public
  * License v2 as published by the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * General Public License for more details.
  *
  * You should have received a copy of the GNU General Public
  * License along with this program; if not, write to the
  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  * Boston, MA 021110-1307, USA.
  */

 #include <linux/init.h>
 #include <linux/fs.h>
 #include <linux/slab.h>
 #include <linux/rwsem.h>
 #include <linux/xattr.h>
 #include "ctree.h"
 #include "btrfs_inode.h"
 #include "transaction.h"
 #include "xattr.h"
 #include "disk-io.h"

 static struct xattr_handler *btrfs_xattr_handler_map[] = {
 	[BTRFS_XATTR_INDEX_USER]		= &btrfs_xattr_user_handler,
 	[BTRFS_XATTR_INDEX_POSIX_ACL_ACCESS]	= &btrfs_xattr_acl_access_handler,
 	[BTRFS_XATTR_INDEX_POSIX_ACL_DEFAULT]	= &btrfs_xattr_acl_default_handler,
 	[BTRFS_XATTR_INDEX_TRUSTED]		= &btrfs_xattr_trusted_handler,
 	[BTRFS_XATTR_INDEX_SECURITY]		= &btrfs_xattr_security_handler,
 	[BTRFS_XATTR_INDEX_SYSTEM]		= &btrfs_xattr_system_handler,
 };

 struct xattr_handler *btrfs_xattr_handlers[] = {
 	&btrfs_xattr_user_handler,
 	&btrfs_xattr_acl_access_handler,
 	&btrfs_xattr_acl_default_handler,
 	&btrfs_xattr_trusted_handler,
 	&btrfs_xattr_security_handler,
 	&btrfs_xattr_system_handler,
 	NULL,
 };

 /*
  * @param name - the xattr name
  * @return - the xattr_handler for the xattr, NULL if its not found
  *
  * use this with listxattr where we don't already know the type of xattr we
  * have
  */
 static struct xattr_handler *find_btrfs_xattr_handler(struct extent_buffer *l,
 						      unsigned long name_ptr,
 						      u16 name_len)
 {
 	struct xattr_handler *handler = NULL;
 	int i = 0;

 	for (handler = btrfs_xattr_handlers[i]; handler != NULL; i++,
 	     handler = btrfs_xattr_handlers[i]) {
 		u16 prefix_len = strlen(handler->prefix);

 		if (name_len < prefix_len)
 			continue;

 		if (memcmp_extent_buffer(l, handler->prefix, name_ptr,
 					 prefix_len) == 0)
 			break;
 	}

 	return handler;
 }

 /*
  * @param name_index - the index for the xattr handler
  * @return the xattr_handler if we found it, NULL otherwise
  *
  * use this if we know the type of the xattr already
  */
 static struct xattr_handler *btrfs_xattr_handler(int name_index)
 {
 	struct xattr_handler *handler = NULL;

 	if (name_index >= 0 &&
 	    name_index < ARRAY_SIZE(btrfs_xattr_handler_map))
 		handler = btrfs_xattr_handler_map[name_index];

 	return handler;
 }

 static inline char *get_name(const char *name, int name_index)
 {
 	char *ret = NULL;
 	struct xattr_handler *handler = btrfs_xattr_handler(name_index);
 	int prefix_len;

 	if (!handler)
 		return ret;

 	prefix_len = strlen(handler->prefix);

 	ret = kmalloc(strlen(name) + prefix_len + 1, GFP_KERNEL);
 	if (!ret)
 		return ret;

 	memcpy(ret, handler->prefix, prefix_len);
 	memcpy(ret+prefix_len, name, strlen(name));
 	ret[prefix_len + strlen(name)] = '\0';

 	return ret;
 }

 size_t btrfs_xattr_generic_list(struct inode *inode, char *list,
 				size_t list_size, const char *name,
 				size_t name_len)
 {
 	if (list && (name_len+1) <= list_size) {
 		memcpy(list, name, name_len);
 		list[name_len] = '\0';
 	} else
 		return -ERANGE;

 	return name_len+1;
 }

 ssize_t btrfs_xattr_get(struct inode *inode, int name_index,
 			const char *attr_name, void *buffer, size_t size)
 {
 	struct btrfs_dir_item *di;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct btrfs_path *path;
 	struct extent_buffer *leaf;
 	struct xattr_handler *handler = btrfs_xattr_handler(name_index);
 	int ret = 0;
 	unsigned long data_ptr;
 	char *name;

 	if (!handler)
 		return -EOPNOTSUPP;

 	/* just in case... */
 	if (*attr_name == '\0')
 		return -EINVAL;

 	name = get_name(attr_name, name_index);
 	if (!name)
 		return -ENOMEM;

 	path = btrfs_alloc_path();
 	if (!path) {
 		kfree(name);
 		return -ENOMEM;
 	}

 	mutex_lock(&root->fs_info->fs_mutex);
 	/* lookup the xattr by name */
 	di = btrfs_lookup_xattr(NULL, root, path, inode->i_ino, name,
 				strlen(name), 0);
 	if (!di || IS_ERR(di)) {
 		ret = -ENODATA;
 		goto out;
 	}

 	leaf = path->nodes[0];
 	/* if size is 0, that means we want the size of the attr */
 	if (!size) {
 		ret = btrfs_dir_data_len(leaf, di);
 		goto out;
 	}

 	/* now get the data out of our dir_item */
 	if (btrfs_dir_data_len(leaf, di) > size) {
 		ret = -ERANGE;
 		goto out;
 	}
 	data_ptr = (unsigned long)((char *)(di + 1) +
 				   btrfs_dir_name_len(leaf, di));
 	read_extent_buffer(leaf, buffer, data_ptr,
 			   btrfs_dir_name_len(leaf, di));
 	ret = btrfs_dir_data_len(leaf, di);

 out:
 	mutex_unlock(&root->fs_info->fs_mutex);
 	kfree(name);
 	btrfs_free_path(path);
 	return ret;
 }

 int btrfs_xattr_set(struct inode *inode, int name_index,
 		    const char *attr_name, const void *value, size_t size,
 		    int flags)
 {
 	struct btrfs_dir_item *di;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct btrfs_trans_handle *trans;
 	struct btrfs_path *path;
 	struct xattr_handler *handler = btrfs_xattr_handler(name_index);
 	char *name;
 	int ret = 0, mod = 0;

 	if (!handler)
 		return -EOPNOTSUPP;

 	/* just in case... */
 	if (*attr_name == '\0')
 		return -EINVAL;

 	name = get_name(attr_name, name_index);
 	if (!name)
 		return -ENOMEM;

 	path = btrfs_alloc_path();
 	if (!path) {
 		kfree(name);
 		return -ENOMEM;
 	}

 	mutex_lock(&root->fs_info->fs_mutex);
 	trans = btrfs_start_transaction(root, 1);
 	btrfs_set_trans_block_group(trans, inode);

 	/* first lets see if we already have this xattr */
 	di = btrfs_lookup_xattr(trans, root, path, inode->i_ino, name,
 				strlen(name), -1);
 	if (IS_ERR(di)) {
 		ret = PTR_ERR(di);
 		goto out;
 	}

 	/* ok we already have this xattr, lets remove it */
 	if (di) {
 		/* if we want create only exit */
 		if (flags & XATTR_CREATE) {
 			ret = -EEXIST;
 			goto out;
 		}

 		ret = btrfs_delete_one_dir_name(trans, root, path, di);
 		if (ret)
 			goto out;
 		btrfs_release_path(root, path);

 		/* if we don't have a value then we are removing the xattr */
 		if (!value) {
 			mod = 1;
 			goto out;
 		}
 	} else if (flags & XATTR_REPLACE) {
 		/* we couldn't find the attr to replace, so error out */
 		ret = -ENODATA;
 		goto out;
 	}

 	/* ok we have to create a completely new xattr */
 	ret = btrfs_insert_xattr_item(trans, root, name, strlen(name),
 				      value, size, inode->i_ino);
 	if (ret)
 		goto out;
 	mod = 1;

 out:
 	if (mod) {
 		inode->i_ctime = CURRENT_TIME;
 		ret = btrfs_update_inode(trans, root, inode);
 	}

 	btrfs_end_transaction(trans, root);
 	mutex_unlock(&root->fs_info->fs_mutex);
 	kfree(name);
 	btrfs_free_path(path);

 	return ret;
 }

 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
 {
 	struct btrfs_key key, found_key;
 	struct inode *inode = dentry->d_inode;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct btrfs_path *path;
 	struct btrfs_item *item;
 	struct extent_buffer *leaf;
 	struct btrfs_dir_item *di;
 	struct xattr_handler *handler;
 	int ret = 0, slot, advance;
 	size_t total_size = 0, size_left = size, written;
 	unsigned long name_ptr;
 	char *name;
 	u32 nritems;

 	/*
 	 * ok we want all objects associated with this id.
 	 * NOTE: we set key.offset = 0; because we want to start with the
 	 * first xattr that we find and walk forward
 	 */
 	key.objectid = inode->i_ino;
 	btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
 	key.offset = 0;

 	path = btrfs_alloc_path();
 	path->reada = 2;
 	if (!path)
 		return -ENOMEM;

 	mutex_lock(&root->fs_info->fs_mutex);

 	/* search for our xattrs */
 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 	if (ret < 0)
 		goto err;
 	ret = 0;
 	advance = 0;
 	while (1) {
 		leaf = path->nodes[0];
 		nritems = btrfs_header_nritems(leaf);
 		slot = path->slots[0];

 		/* this is where we start walking through the path */
 		if (advance || slot >= nritems) {
 			/*
 			 * if we've reached the last slot in this leaf we need
 			 * to go to the next leaf and reset everything
 			 */
 			if (slot >= nritems-1) {
 				ret = btrfs_next_leaf(root, path);
 				if (ret)
 					break;
 				leaf = path->nodes[0];
 				nritems = btrfs_header_nritems(leaf);
 				slot = path->slots[0];
 			} else {
 				/*
 				 * just walking through the slots on this leaf
 				 */
 				slot++;
 				path->slots[0]++;
 			}
 		}
 		advance = 1;

 		item = btrfs_item_nr(leaf, slot);
 		btrfs_item_key_to_cpu(leaf, &found_key, slot);

 		/* check to make sure this item is what we want */
 		if (found_key.objectid != key.objectid)
 			break;
 		if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY)
 			break;

 		di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);

 		total_size += btrfs_dir_name_len(leaf, di)+1;

 		/* we are just looking for how big our buffer needs to be */
 		if (!size)
 			continue;

 		/* find our handler for this xattr */
 		name_ptr = (unsigned long)(di + 1);
 		handler = find_btrfs_xattr_handler(leaf, name_ptr,
 						   btrfs_dir_name_len(leaf, di));
 		if (!handler) {
 			printk(KERN_ERR "btrfs: unsupported xattr found\n");
 			continue;
 		}

 		name = kmalloc(btrfs_dir_name_len(leaf, di), GFP_KERNEL);
 		read_extent_buffer(leaf, name, name_ptr,
 				   btrfs_dir_name_len(leaf, di));

 		/* call the list function associated with this xattr */
 		written = handler->list(inode, buffer, size_left, name,
 					btrfs_dir_name_len(leaf, di));
 		kfree(name);

 		if (written < 0) {
 			ret = -ERANGE;
 			break;
 		}

 		size_left -= written;
 		buffer += written;
 	}
 	ret = total_size;

 err:
 	mutex_unlock(&root->fs_info->fs_mutex);
 	btrfs_free_path(path);

 	return ret;
 }

 /*
  * delete all the xattrs associated with the inode.  fs_mutex should be
  * held when we come into here
  */
 int btrfs_delete_xattrs(struct btrfs_trans_handle *trans,
 			struct btrfs_root *root, struct inode *inode)
 {
 	struct btrfs_path *path;
 	struct btrfs_key key, found_key;
 	struct btrfs_item *item;
 	struct extent_buffer *leaf;
 	int ret;

 	path = btrfs_alloc_path();
 	if (!path)
 		return -ENOMEM;

 	key.objectid = inode->i_ino;
 	btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
 	key.offset = (u64)-1;

 	while(1) {
 		/* look for our next xattr */
 		ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 		if (ret < 0)
 			goto out;
 		BUG_ON(ret == 0);

 		if (path->slots[0] == 0)
 			break;

 		path->slots[0]--;
 		leaf = path->nodes[0];
 		item = btrfs_item_nr(leaf, path->slots[0]);
 		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);

 		if (found_key.objectid != key.objectid)
 			break;
 		if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY)
 			break;

 		ret = btrfs_del_item(trans, root, path);
 		BUG_ON(ret);
 		btrfs_release_path(root, path);
 	}
 	ret = 0;
 out:
 	btrfs_free_path(path);

 	return ret;
 }

 /*
  * Handler functions
  */
 #define BTRFS_XATTR_SETGET_FUNCS(name, index)				\
 static int btrfs_xattr_##name##_get(struct inode *inode,		\
 				    const char *name, void *value,	\
 				    size_t size)			\
 {									\
 	return btrfs_xattr_get(inode, index, name, value, size);	\
 }									\
 static int btrfs_xattr_##name##_set(struct inode *inode,		\
 				    const char *name, const void *value,\
 				    size_t size, int flags)		\
 {									\
 	return btrfs_xattr_set(inode, index, name, value, size, flags);	\
 }									\

 BTRFS_XATTR_SETGET_FUNCS(security, BTRFS_XATTR_INDEX_SECURITY);
 BTRFS_XATTR_SETGET_FUNCS(system, BTRFS_XATTR_INDEX_SYSTEM);
 BTRFS_XATTR_SETGET_FUNCS(user, BTRFS_XATTR_INDEX_USER);
 BTRFS_XATTR_SETGET_FUNCS(trusted, BTRFS_XATTR_INDEX_TRUSTED);

 struct xattr_handler btrfs_xattr_security_handler = {
 	.prefix = XATTR_SECURITY_PREFIX,
 	.list	= btrfs_xattr_generic_list,
 	.get	= btrfs_xattr_security_get,
 	.set	= btrfs_xattr_security_set,
 };

 struct xattr_handler btrfs_xattr_system_handler = {
 	.prefix = XATTR_SYSTEM_PREFIX,
 	.list	= btrfs_xattr_generic_list,
 	.get	= btrfs_xattr_system_get,
 	.set	= btrfs_xattr_system_set,
 };

 struct xattr_handler btrfs_xattr_user_handler = {
 	.prefix	= XATTR_USER_PREFIX,
 	.list	= btrfs_xattr_generic_list,
 	.get	= btrfs_xattr_user_get,
 	.set	= btrfs_xattr_user_set,
 };

 struct xattr_handler btrfs_xattr_trusted_handler = {
 	.prefix = XATTR_USER_PREFIX,
 	.list	= btrfs_xattr_generic_list,
 	.get	= btrfs_xattr_trusted_get,
 	.set	= btrfs_xattr_trusted_set,
 };
	/*
	* Copyright (C) 2007 Red Hat. All rights reserved.
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public
	* License v2 as published by the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* General Public License for more details.
	*
	* You should have received a copy of the GNU General Public
	* License along with this program; if not, write to the
	* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	* Boston, MA 021110-1307, USA.
	*/

	#include <linux/init.h>
	#include <linux/fs.h>
	#include <linux/slab.h>
	#include <linux/rwsem.h>
	#include <linux/xattr.h>
	#include "ctree.h"
	#include "btrfs_inode.h"
	#include "transaction.h"
	#include "xattr.h"
	#include "disk-io.h"

	static struct xattr_handler *btrfs_xattr_handler_map[] = {
	[BTRFS_XATTR_INDEX_USER] = &btrfs_xattr_user_handler,
	[BTRFS_XATTR_INDEX_POSIX_ACL_ACCESS] = &btrfs_xattr_acl_access_handler,
	[BTRFS_XATTR_INDEX_POSIX_ACL_DEFAULT] = &btrfs_xattr_acl_default_handler,
	[BTRFS_XATTR_INDEX_TRUSTED] = &btrfs_xattr_trusted_handler,
	[BTRFS_XATTR_INDEX_SECURITY] = &btrfs_xattr_security_handler,
	[BTRFS_XATTR_INDEX_SYSTEM] = &btrfs_xattr_system_handler,
	};

	struct xattr_handler *btrfs_xattr_handlers[] = {
	&btrfs_xattr_user_handler,
	&btrfs_xattr_acl_access_handler,
	&btrfs_xattr_acl_default_handler,
	&btrfs_xattr_trusted_handler,
	&btrfs_xattr_security_handler,
	&btrfs_xattr_system_handler,
	NULL,
	};

	/*
	* @param name - the xattr name
	* @return - the xattr_handler for the xattr, NULL if its not found
	*
	* use this with listxattr where we don't already know the type of xattr we
	* have
	*/
	static struct xattr_handler find_btrfs_xattr_handler(struct extent_buffer l,
	unsigned long name_ptr,
	u16 name_len)
	{
	struct xattr_handler *handler = NULL;
	int i = 0;

	for (handler = btrfs_xattr_handlers[i]; handler != NULL; i++,
	handler = btrfs_xattr_handlers[i]) {
	u16 prefix_len = strlen(handler->prefix);

	if (name_len < prefix_len)
	continue;

	if (memcmp_extent_buffer(l, handler->prefix, name_ptr,
	prefix_len) == 0)
	break;
	}

	return handler;
	}

	/*
	* @param name_index - the index for the xattr handler
	* @return the xattr_handler if we found it, NULL otherwise
	*
	* use this if we know the type of the xattr already
	*/
	static struct xattr_handler *btrfs_xattr_handler(int name_index)
	{
	struct xattr_handler *handler = NULL;

	if (name_index >= 0 &&
	name_index < ARRAY_SIZE(btrfs_xattr_handler_map))
	handler = btrfs_xattr_handler_map[name_index];

	return handler;
	}

	static inline char get_name(const char name, int name_index)
	{
	char *ret = NULL;
	struct xattr_handler *handler = btrfs_xattr_handler(name_index);
	int prefix_len;

	if (!handler)
	return ret;

	prefix_len = strlen(handler->prefix);

	ret = kmalloc(strlen(name) + prefix_len + 1, GFP_KERNEL);
	if (!ret)
	return ret;

	memcpy(ret, handler->prefix, prefix_len);
	memcpy(ret+prefix_len, name, strlen(name));
	ret[prefix_len + strlen(name)] = '\0';

	return ret;
	}

	size_t btrfs_xattr_generic_list(struct inode inode, char list,
	size_t list_size, const char *name,
	size_t name_len)
	{
	if (list && (name_len+1) <= list_size) {
	memcpy(list, name, name_len);
	list[name_len] = '\0';
	} else
	return -ERANGE;

	return name_len+1;
	}

	ssize_t btrfs_xattr_get(struct inode *inode, int name_index,
	const char attr_name, void buffer, size_t size)
	{
	struct btrfs_dir_item *di;
	struct btrfs_root *root = BTRFS_I(inode)->root;
	struct btrfs_path *path;
	struct extent_buffer *leaf;
	struct xattr_handler *handler = btrfs_xattr_handler(name_index);
	int ret = 0;
	unsigned long data_ptr;
	char *name;

	if (!handler)
	return -EOPNOTSUPP;

	/* just in case... */
	if (*attr_name == '\0')
	return -EINVAL;

	name = get_name(attr_name, name_index);
	if (!name)
	return -ENOMEM;

	path = btrfs_alloc_path();
	if (!path) {
	kfree(name);
	return -ENOMEM;
	}

	mutex_lock(&root->fs_info->fs_mutex);
	/* lookup the xattr by name */
	di = btrfs_lookup_xattr(NULL, root, path, inode->i_ino, name,
	strlen(name), 0);
	if (!di \|\| IS_ERR(di)) {
	ret = -ENODATA;
	goto out;
	}

	leaf = path->nodes[0];
	/* if size is 0, that means we want the size of the attr */
	if (!size) {
	ret = btrfs_dir_data_len(leaf, di);
	goto out;
	}

	/* now get the data out of our dir_item */
	if (btrfs_dir_data_len(leaf, di) > size) {
	ret = -ERANGE;
	goto out;
	}
	data_ptr = (unsigned long)((char *)(di + 1) +
	btrfs_dir_name_len(leaf, di));
	read_extent_buffer(leaf, buffer, data_ptr,
	btrfs_dir_name_len(leaf, di));
	ret = btrfs_dir_data_len(leaf, di);

	out:
	mutex_unlock(&root->fs_info->fs_mutex);
	kfree(name);
	btrfs_free_path(path);
	return ret;
	}

	int btrfs_xattr_set(struct inode *inode, int name_index,
	const char attr_name, const void value, size_t size,
	int flags)
	{
	struct btrfs_dir_item *di;
	struct btrfs_root *root = BTRFS_I(inode)->root;
	struct btrfs_trans_handle *trans;
	struct btrfs_path *path;
	struct xattr_handler *handler = btrfs_xattr_handler(name_index);
	char *name;
	int ret = 0, mod = 0;

	if (!handler)
	return -EOPNOTSUPP;

	/* just in case... */
	if (*attr_name == '\0')
	return -EINVAL;

	name = get_name(attr_name, name_index);
	if (!name)
	return -ENOMEM;

	path = btrfs_alloc_path();
	if (!path) {
	kfree(name);
	return -ENOMEM;
	}

	mutex_lock(&root->fs_info->fs_mutex);
	trans = btrfs_start_transaction(root, 1);
	btrfs_set_trans_block_group(trans, inode);

	/* first lets see if we already have this xattr */
	di = btrfs_lookup_xattr(trans, root, path, inode->i_ino, name,
	strlen(name), -1);
	if (IS_ERR(di)) {
	ret = PTR_ERR(di);
	goto out;
	}

	/* ok we already have this xattr, lets remove it */
	if (di) {
	/* if we want create only exit */
	if (flags & XATTR_CREATE) {
	ret = -EEXIST;
	goto out;
	}

	ret = btrfs_delete_one_dir_name(trans, root, path, di);
	if (ret)
	goto out;
	btrfs_release_path(root, path);

	/* if we don't have a value then we are removing the xattr */
	if (!value) {
	mod = 1;
	goto out;
	}
	} else if (flags & XATTR_REPLACE) {
	/* we couldn't find the attr to replace, so error out */
	ret = -ENODATA;
	goto out;
	}

	/* ok we have to create a completely new xattr */
	ret = btrfs_insert_xattr_item(trans, root, name, strlen(name),
	value, size, inode->i_ino);
	if (ret)
	goto out;
	mod = 1;

	out:
	if (mod) {
	inode->i_ctime = CURRENT_TIME;
	ret = btrfs_update_inode(trans, root, inode);
	}

	btrfs_end_transaction(trans, root);
	mutex_unlock(&root->fs_info->fs_mutex);
	kfree(name);
	btrfs_free_path(path);

	return ret;
	}

	ssize_t btrfs_listxattr(struct dentry dentry, char buffer, size_t size)
	{
	struct btrfs_key key, found_key;
	struct inode *inode = dentry->d_inode;
	struct btrfs_root *root = BTRFS_I(inode)->root;
	struct btrfs_path *path;
	struct btrfs_item *item;
	struct extent_buffer *leaf;
	struct btrfs_dir_item *di;
	struct xattr_handler *handler;
	int ret = 0, slot, advance;
	size_t total_size = 0, size_left = size, written;
	unsigned long name_ptr;
	char *name;
	u32 nritems;

	/*
	* ok we want all objects associated with this id.
	* NOTE: we set key.offset = 0; because we want to start with the
	* first xattr that we find and walk forward
	*/
	key.objectid = inode->i_ino;
	btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
	key.offset = 0;

	path = btrfs_alloc_path();
	path->reada = 2;
	if (!path)
	return -ENOMEM;

	mutex_lock(&root->fs_info->fs_mutex);

	/* search for our xattrs */
	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
	if (ret < 0)
	goto err;
	ret = 0;
	advance = 0;
	while (1) {
	leaf = path->nodes[0];
	nritems = btrfs_header_nritems(leaf);
	slot = path->slots[0];

	/* this is where we start walking through the path */
	if (advance \|\| slot >= nritems) {
	/*
	* if we've reached the last slot in this leaf we need
	* to go to the next leaf and reset everything
	*/
	if (slot >= nritems-1) {
	ret = btrfs_next_leaf(root, path);
	if (ret)
	break;
	leaf = path->nodes[0];
	nritems = btrfs_header_nritems(leaf);
	slot = path->slots[0];
	} else {
	/*
	* just walking through the slots on this leaf
	*/
	slot++;
	path->slots[0]++;
	}
	}
	advance = 1;

	item = btrfs_item_nr(leaf, slot);
	btrfs_item_key_to_cpu(leaf, &found_key, slot);

	/* check to make sure this item is what we want */
	if (found_key.objectid != key.objectid)
	break;
	if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY)
	break;

	di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);

	total_size += btrfs_dir_name_len(leaf, di)+1;

	/* we are just looking for how big our buffer needs to be */
	if (!size)
	continue;

	/* find our handler for this xattr */
	name_ptr = (unsigned long)(di + 1);
	handler = find_btrfs_xattr_handler(leaf, name_ptr,
	btrfs_dir_name_len(leaf, di));
	if (!handler) {
	printk(KERN_ERR "btrfs: unsupported xattr found\n");
	continue;
	}

	name = kmalloc(btrfs_dir_name_len(leaf, di), GFP_KERNEL);
	read_extent_buffer(leaf, name, name_ptr,
	btrfs_dir_name_len(leaf, di));

	/* call the list function associated with this xattr */
	written = handler->list(inode, buffer, size_left, name,
	btrfs_dir_name_len(leaf, di));
	kfree(name);

	if (written < 0) {
	ret = -ERANGE;
	break;
	}

	size_left -= written;
	buffer += written;
	}
	ret = total_size;

	err:
	mutex_unlock(&root->fs_info->fs_mutex);
	btrfs_free_path(path);

	return ret;
	}

	/*
	* delete all the xattrs associated with the inode. fs_mutex should be
	* held when we come into here
	*/
	int btrfs_delete_xattrs(struct btrfs_trans_handle *trans,
	struct btrfs_root root, struct inode inode)
	{
	struct btrfs_path *path;
	struct btrfs_key key, found_key;
	struct btrfs_item *item;
	struct extent_buffer *leaf;
	int ret;

	path = btrfs_alloc_path();
	if (!path)
	return -ENOMEM;

	key.objectid = inode->i_ino;
	btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
	key.offset = (u64)-1;

	while(1) {
	/* look for our next xattr */
	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
	if (ret < 0)
	goto out;
	BUG_ON(ret == 0);

	if (path->slots[0] == 0)
	break;

	path->slots[0]--;
	leaf = path->nodes[0];
	item = btrfs_item_nr(leaf, path->slots[0]);
	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);

	if (found_key.objectid != key.objectid)
	break;
	if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY)
	break;

	ret = btrfs_del_item(trans, root, path);
	BUG_ON(ret);
	btrfs_release_path(root, path);
	}
	ret = 0;
	out:
	btrfs_free_path(path);

	return ret;
	}

	/*
	* Handler functions
	*/
	#define BTRFS_XATTR_SETGET_FUNCS(name, index) \
	static int btrfs_xattr_##name##_get(struct inode *inode, \
	const char name, void value, \
	size_t size) \
	{ \
	return btrfs_xattr_get(inode, index, name, value, size); \
	} \
	static int btrfs_xattr_##name##_set(struct inode *inode, \
	const char name, const void value,\
	size_t size, int flags) \
	{ \
	return btrfs_xattr_set(inode, index, name, value, size, flags); \
	} \

	BTRFS_XATTR_SETGET_FUNCS(security, BTRFS_XATTR_INDEX_SECURITY);
	BTRFS_XATTR_SETGET_FUNCS(system, BTRFS_XATTR_INDEX_SYSTEM);
	BTRFS_XATTR_SETGET_FUNCS(user, BTRFS_XATTR_INDEX_USER);
	BTRFS_XATTR_SETGET_FUNCS(trusted, BTRFS_XATTR_INDEX_TRUSTED);

	struct xattr_handler btrfs_xattr_security_handler = {
	.prefix = XATTR_SECURITY_PREFIX,
	.list = btrfs_xattr_generic_list,
	.get = btrfs_xattr_security_get,
	.set = btrfs_xattr_security_set,
	};

	struct xattr_handler btrfs_xattr_system_handler = {
	.prefix = XATTR_SYSTEM_PREFIX,
	.list = btrfs_xattr_generic_list,
	.get = btrfs_xattr_system_get,
	.set = btrfs_xattr_system_set,
	};

	struct xattr_handler btrfs_xattr_user_handler = {
	.prefix = XATTR_USER_PREFIX,
	.list = btrfs_xattr_generic_list,
	.get = btrfs_xattr_user_get,
	.set = btrfs_xattr_user_set,
	};

	struct xattr_handler btrfs_xattr_trusted_handler = {
	.prefix = XATTR_USER_PREFIX,
	.list = btrfs_xattr_generic_list,
	.get = btrfs_xattr_trusted_get,
	.set = btrfs_xattr_trusted_set,
	};