fs/btrfs/xattr.c - kernel/mindspeed - Git at Google

 /*
  * 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 <linux/security.h>
 #include "ctree.h"
 #include "btrfs_inode.h"
 #include "transaction.h"
 #include "xattr.h"
 #include "disk-io.h"


 ssize_t __btrfs_getxattr(struct inode *inode, const char *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;
 	int ret = 0;
 	unsigned long data_ptr;

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

 	/* lookup the xattr by name */
 	di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(inode), name,
 				strlen(name), 0);
 	if (!di) {
 		ret = -ENODATA;
 		goto out;
 	} else if (IS_ERR(di)) {
 		ret = PTR_ERR(di);
 		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;
 	}

 	/*
 	 * The way things are packed into the leaf is like this
 	 * |struct btrfs_dir_item|name|data|
 	 * where name is the xattr name, so security.foo, and data is the
 	 * content of the xattr.  data_ptr points to the location in memory
 	 * where the data starts in the in memory leaf
 	 */
 	data_ptr = (unsigned long)((char *)(di + 1) +
 				   btrfs_dir_name_len(leaf, di));
 	read_extent_buffer(leaf, buffer, data_ptr,
 			   btrfs_dir_data_len(leaf, di));
 	ret = btrfs_dir_data_len(leaf, di);

 out:
 	btrfs_free_path(path);
 	return ret;
 }

 static int do_setxattr(struct btrfs_trans_handle *trans,
 		       struct inode *inode, const char *name,
 		       const void *value, size_t size, int flags)
 {
 	struct btrfs_dir_item *di;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct btrfs_path *path;
 	size_t name_len = strlen(name);
 	int ret = 0;

 	if (name_len + size > BTRFS_MAX_XATTR_SIZE(root))
 		return -ENOSPC;

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

 	if (flags & XATTR_REPLACE) {
 		di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), name,
 					name_len, -1);
 		if (IS_ERR(di)) {
 			ret = PTR_ERR(di);
 			goto out;
 		} else if (!di) {
 			ret = -ENODATA;
 			goto out;
 		}
 		ret = btrfs_delete_one_dir_name(trans, root, path, di);
 		if (ret)
 			goto out;
 		btrfs_release_path(path);

 		/*
 		 * remove the attribute
 		 */
 		if (!value)
 			goto out;
 	}

 again:
 	ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(inode),
 				      name, name_len, value, size);
 	/*
 	 * If we're setting an xattr to a new value but the new value is say
 	 * exactly BTRFS_MAX_XATTR_SIZE, we could end up with EOVERFLOW getting
 	 * back from split_leaf.  This is because it thinks we'll be extending
 	 * the existing item size, but we're asking for enough space to add the
 	 * item itself.  So if we get EOVERFLOW just set ret to EEXIST and let
 	 * the rest of the function figure it out.
 	 */
 	if (ret == -EOVERFLOW)
 		ret = -EEXIST;

 	if (ret == -EEXIST) {
 		if (flags & XATTR_CREATE)
 			goto out;
 		/*
 		 * We can't use the path we already have since we won't have the
 		 * proper locking for a delete, so release the path and
 		 * re-lookup to delete the thing.
 		 */
 		btrfs_release_path(path);
 		di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode),
 					name, name_len, -1);
 		if (IS_ERR(di)) {
 			ret = PTR_ERR(di);
 			goto out;
 		} else if (!di) {
 			/* Shouldn't happen but just in case... */
 			btrfs_release_path(path);
 			goto again;
 		}

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

 		/*
 		 * We have a value to set, so go back and try to insert it now.
 		 */
 		if (value) {
 			btrfs_release_path(path);
 			goto again;
 		}
 	}
 out:
 	btrfs_free_path(path);
 	return ret;
 }

 /*
  * @value: "" makes the attribute to empty, NULL removes it
  */
 int __btrfs_setxattr(struct btrfs_trans_handle *trans,
 		     struct inode *inode, const char *name,
 		     const void *value, size_t size, int flags)
 {
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	int ret;

 	if (trans)
 		return do_setxattr(trans, inode, name, value, size, flags);

 	trans = btrfs_start_transaction(root, 2);
 	if (IS_ERR(trans))
 		return PTR_ERR(trans);

 	ret = do_setxattr(trans, inode, name, value, size, flags);
 	if (ret)
 		goto out;

 	inode->i_ctime = CURRENT_TIME;
 	ret = btrfs_update_inode(trans, root, inode);
 	BUG_ON(ret);
 out:
 	btrfs_end_transaction_throttle(trans, root);
 	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 extent_buffer *leaf;
 	struct btrfs_dir_item *di;
 	int ret = 0, slot;
 	size_t total_size = 0, size_left = size;
 	unsigned long name_ptr;
 	size_t name_len;

 	/*
 	 * 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 = btrfs_ino(inode);
 	btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
 	key.offset = 0;

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

 	/* search for our xattrs */
 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 	if (ret < 0)
 		goto err;

 	while (1) {
 		leaf = path->nodes[0];
 		slot = path->slots[0];

 		/* this is where we start walking through the path */
 		if (slot >= btrfs_header_nritems(leaf)) {
 			/*
 			 * if we've reached the last slot in this leaf we need
 			 * to go to the next leaf and reset everything
 			 */
 			ret = btrfs_next_leaf(root, path);
 			if (ret < 0)
 				goto err;
 			else if (ret > 0)
 				break;
 			continue;
 		}

 		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);
 		if (verify_dir_item(root, leaf, di))
 			continue;

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

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

 		if (!buffer || (name_len + 1) > size_left) {
 			ret = -ERANGE;
 			goto err;
 		}

 		name_ptr = (unsigned long)(di + 1);
 		read_extent_buffer(leaf, buffer, name_ptr, name_len);
 		buffer[name_len] = '\0';

 		size_left -= name_len + 1;
 		buffer += name_len + 1;
 next:
 		path->slots[0]++;
 	}
 	ret = total_size;

 err:
 	btrfs_free_path(path);

 	return ret;
 }

 /*
  * List of handlers for synthetic system.* attributes.  All real ondisk
  * attributes are handled directly.
  */
 const struct xattr_handler *btrfs_xattr_handlers[] = {
 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 	&btrfs_xattr_acl_access_handler,
 	&btrfs_xattr_acl_default_handler,
 #endif
 	NULL,
 };

 /*
  * Check if the attribute is in a supported namespace.
  *
  * This applied after the check for the synthetic attributes in the system
  * namespace.
  */
 static bool btrfs_is_valid_xattr(const char *name)
 {
 	return !strncmp(name, XATTR_SECURITY_PREFIX,
 			XATTR_SECURITY_PREFIX_LEN) ||
 	       !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) ||
 	       !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) ||
 	       !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN);
 }

 ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
 		       void *buffer, size_t size)
 {
 	/*
 	 * If this is a request for a synthetic attribute in the system.*
 	 * namespace use the generic infrastructure to resolve a handler
 	 * for it via sb->s_xattr.
 	 */
 	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
 		return generic_getxattr(dentry, name, buffer, size);

 	if (!btrfs_is_valid_xattr(name))
 		return -EOPNOTSUPP;
 	return __btrfs_getxattr(dentry->d_inode, name, buffer, size);
 }

 int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 		   size_t size, int flags)
 {
 	struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;

 	/*
 	 * The permission on security.* and system.* is not checked
 	 * in permission().
 	 */
 	if (btrfs_root_readonly(root))
 		return -EROFS;

 	/*
 	 * If this is a request for a synthetic attribute in the system.*
 	 * namespace use the generic infrastructure to resolve a handler
 	 * for it via sb->s_xattr.
 	 */
 	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
 		return generic_setxattr(dentry, name, value, size, flags);

 	if (!btrfs_is_valid_xattr(name))
 		return -EOPNOTSUPP;

 	if (size == 0)
 		value = "";  /* empty EA, do not remove */

 	return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size,
 				flags);
 }

 int btrfs_removexattr(struct dentry *dentry, const char *name)
 {
 	struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;

 	/*
 	 * The permission on security.* and system.* is not checked
 	 * in permission().
 	 */
 	if (btrfs_root_readonly(root))
 		return -EROFS;

 	/*
 	 * If this is a request for a synthetic attribute in the system.*
 	 * namespace use the generic infrastructure to resolve a handler
 	 * for it via sb->s_xattr.
 	 */
 	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
 		return generic_removexattr(dentry, name);

 	if (!btrfs_is_valid_xattr(name))
 		return -EOPNOTSUPP;

 	return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0,
 				XATTR_REPLACE);
 }

 int btrfs_initxattrs(struct inode *inode, const struct xattr *xattr_array,
 		     void *fs_info)
 {
 	const struct xattr *xattr;
 	struct btrfs_trans_handle *trans = fs_info;
 	char *name;
 	int err = 0;

 	for (xattr = xattr_array; xattr->name != NULL; xattr++) {
 		name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
 			       strlen(xattr->name) + 1, GFP_NOFS);
 		if (!name) {
 			err = -ENOMEM;
 			break;
 		}
 		strcpy(name, XATTR_SECURITY_PREFIX);
 		strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
 		err = __btrfs_setxattr(trans, inode, name,
 				       xattr->value, xattr->value_len, 0);
 		kfree(name);
 		if (err < 0)
 			break;
 	}
 	return err;
 }

 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans,
 			      struct inode *inode, struct inode *dir,
 			      const struct qstr *qstr)
 {
 	return security_inode_init_security(inode, dir, qstr,
 					    &btrfs_initxattrs, trans);
 }
	/*
	* 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 <linux/security.h>
	#include "ctree.h"
	#include "btrfs_inode.h"
	#include "transaction.h"
	#include "xattr.h"
	#include "disk-io.h"


	ssize_t __btrfs_getxattr(struct inode inode, const char 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;
	int ret = 0;
	unsigned long data_ptr;

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

	/* lookup the xattr by name */
	di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(inode), name,
	strlen(name), 0);
	if (!di) {
	ret = -ENODATA;
	goto out;
	} else if (IS_ERR(di)) {
	ret = PTR_ERR(di);
	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;
	}

	/*
	* The way things are packed into the leaf is like this
	* \|struct btrfs_dir_item\|name\|data\|
	* where name is the xattr name, so security.foo, and data is the
	* content of the xattr. data_ptr points to the location in memory
	* where the data starts in the in memory leaf
	*/
	data_ptr = (unsigned long)((char *)(di + 1) +
	btrfs_dir_name_len(leaf, di));
	read_extent_buffer(leaf, buffer, data_ptr,
	btrfs_dir_data_len(leaf, di));
	ret = btrfs_dir_data_len(leaf, di);

	out:
	btrfs_free_path(path);
	return ret;
	}

	static int do_setxattr(struct btrfs_trans_handle *trans,
	struct inode inode, const char name,
	const void *value, size_t size, int flags)
	{
	struct btrfs_dir_item *di;
	struct btrfs_root *root = BTRFS_I(inode)->root;
	struct btrfs_path *path;
	size_t name_len = strlen(name);
	int ret = 0;

	if (name_len + size > BTRFS_MAX_XATTR_SIZE(root))
	return -ENOSPC;

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

	if (flags & XATTR_REPLACE) {
	di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), name,
	name_len, -1);
	if (IS_ERR(di)) {
	ret = PTR_ERR(di);
	goto out;
	} else if (!di) {
	ret = -ENODATA;
	goto out;
	}
	ret = btrfs_delete_one_dir_name(trans, root, path, di);
	if (ret)
	goto out;
	btrfs_release_path(path);

	/*
	* remove the attribute
	*/
	if (!value)
	goto out;
	}

	again:
	ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(inode),
	name, name_len, value, size);
	/*
	* If we're setting an xattr to a new value but the new value is say
	* exactly BTRFS_MAX_XATTR_SIZE, we could end up with EOVERFLOW getting
	* back from split_leaf. This is because it thinks we'll be extending
	* the existing item size, but we're asking for enough space to add the
	* item itself. So if we get EOVERFLOW just set ret to EEXIST and let
	* the rest of the function figure it out.
	*/
	if (ret == -EOVERFLOW)
	ret = -EEXIST;

	if (ret == -EEXIST) {
	if (flags & XATTR_CREATE)
	goto out;
	/*
	* We can't use the path we already have since we won't have the
	* proper locking for a delete, so release the path and
	* re-lookup to delete the thing.
	*/
	btrfs_release_path(path);
	di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode),
	name, name_len, -1);
	if (IS_ERR(di)) {
	ret = PTR_ERR(di);
	goto out;
	} else if (!di) {
	/* Shouldn't happen but just in case... */
	btrfs_release_path(path);
	goto again;
	}

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

	/*
	* We have a value to set, so go back and try to insert it now.
	*/
	if (value) {
	btrfs_release_path(path);
	goto again;
	}
	}
	out:
	btrfs_free_path(path);
	return ret;
	}

	/*
	* @value: "" makes the attribute to empty, NULL removes it
	*/
	int __btrfs_setxattr(struct btrfs_trans_handle *trans,
	struct inode inode, const char name,
	const void *value, size_t size, int flags)
	{
	struct btrfs_root *root = BTRFS_I(inode)->root;
	int ret;

	if (trans)
	return do_setxattr(trans, inode, name, value, size, flags);

	trans = btrfs_start_transaction(root, 2);
	if (IS_ERR(trans))
	return PTR_ERR(trans);

	ret = do_setxattr(trans, inode, name, value, size, flags);
	if (ret)
	goto out;

	inode->i_ctime = CURRENT_TIME;
	ret = btrfs_update_inode(trans, root, inode);
	BUG_ON(ret);
	out:
	btrfs_end_transaction_throttle(trans, root);
	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 extent_buffer *leaf;
	struct btrfs_dir_item *di;
	int ret = 0, slot;
	size_t total_size = 0, size_left = size;
	unsigned long name_ptr;
	size_t name_len;

	/*
	* 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 = btrfs_ino(inode);
	btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
	key.offset = 0;

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

	/* search for our xattrs */
	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
	if (ret < 0)
	goto err;

	while (1) {
	leaf = path->nodes[0];
	slot = path->slots[0];

	/* this is where we start walking through the path */
	if (slot >= btrfs_header_nritems(leaf)) {
	/*
	* if we've reached the last slot in this leaf we need
	* to go to the next leaf and reset everything
	*/
	ret = btrfs_next_leaf(root, path);
	if (ret < 0)
	goto err;
	else if (ret > 0)
	break;
	continue;
	}

	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);
	if (verify_dir_item(root, leaf, di))
	continue;

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

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

	if (!buffer \|\| (name_len + 1) > size_left) {
	ret = -ERANGE;
	goto err;
	}

	name_ptr = (unsigned long)(di + 1);
	read_extent_buffer(leaf, buffer, name_ptr, name_len);
	buffer[name_len] = '\0';

	size_left -= name_len + 1;
	buffer += name_len + 1;
	next:
	path->slots[0]++;
	}
	ret = total_size;

	err:
	btrfs_free_path(path);

	return ret;
	}

	/*
	* List of handlers for synthetic system.* attributes. All real ondisk
	* attributes are handled directly.
	*/
	const struct xattr_handler *btrfs_xattr_handlers[] = {
	#ifdef CONFIG_BTRFS_FS_POSIX_ACL
	&btrfs_xattr_acl_access_handler,
	&btrfs_xattr_acl_default_handler,
	#endif
	NULL,
	};

	/*
	* Check if the attribute is in a supported namespace.
	*
	* This applied after the check for the synthetic attributes in the system
	* namespace.
	*/
	static bool btrfs_is_valid_xattr(const char *name)
	{
	return !strncmp(name, XATTR_SECURITY_PREFIX,
	XATTR_SECURITY_PREFIX_LEN) \|\|
	!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) \|\|
	!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) \|\|
	!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN);
	}

	ssize_t btrfs_getxattr(struct dentry dentry, const char name,
	void *buffer, size_t size)
	{
	/*
	* If this is a request for a synthetic attribute in the system.*
	* namespace use the generic infrastructure to resolve a handler
	* for it via sb->s_xattr.
	*/
	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
	return generic_getxattr(dentry, name, buffer, size);

	if (!btrfs_is_valid_xattr(name))
	return -EOPNOTSUPP;
	return __btrfs_getxattr(dentry->d_inode, name, buffer, size);
	}

	int btrfs_setxattr(struct dentry dentry, const char name, const void *value,
	size_t size, int flags)
	{
	struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;

	/*
	* The permission on security.* and system.* is not checked
	* in permission().
	*/
	if (btrfs_root_readonly(root))
	return -EROFS;

	/*
	* If this is a request for a synthetic attribute in the system.*
	* namespace use the generic infrastructure to resolve a handler
	* for it via sb->s_xattr.
	*/
	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
	return generic_setxattr(dentry, name, value, size, flags);

	if (!btrfs_is_valid_xattr(name))
	return -EOPNOTSUPP;

	if (size == 0)
	value = ""; /* empty EA, do not remove */

	return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size,
	flags);
	}

	int btrfs_removexattr(struct dentry dentry, const char name)
	{
	struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;

	/*
	* The permission on security.* and system.* is not checked
	* in permission().
	*/
	if (btrfs_root_readonly(root))
	return -EROFS;

	/*
	* If this is a request for a synthetic attribute in the system.*
	* namespace use the generic infrastructure to resolve a handler
	* for it via sb->s_xattr.
	*/
	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
	return generic_removexattr(dentry, name);

	if (!btrfs_is_valid_xattr(name))
	return -EOPNOTSUPP;

	return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0,
	XATTR_REPLACE);
	}

	int btrfs_initxattrs(struct inode inode, const struct xattr xattr_array,
	void *fs_info)
	{
	const struct xattr *xattr;
	struct btrfs_trans_handle *trans = fs_info;
	char *name;
	int err = 0;

	for (xattr = xattr_array; xattr->name != NULL; xattr++) {
	name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
	strlen(xattr->name) + 1, GFP_NOFS);
	if (!name) {
	err = -ENOMEM;
	break;
	}
	strcpy(name, XATTR_SECURITY_PREFIX);
	strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
	err = __btrfs_setxattr(trans, inode, name,
	xattr->value, xattr->value_len, 0);
	kfree(name);
	if (err < 0)
	break;
	}
	return err;
	}

	int btrfs_xattr_security_init(struct btrfs_trans_handle *trans,
	struct inode inode, struct inode dir,
	const struct qstr *qstr)
	{
	return security_inode_init_security(inode, dir, qstr,
	&btrfs_initxattrs, trans);
	}