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kernel/linux-imx6_3.14.28/fs/btrfs/acl.c 3.76 KB
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  /*
   * 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/fs.h>
  #include <linux/string.h>
  #include <linux/xattr.h>
  #include <linux/posix_acl_xattr.h>
  #include <linux/posix_acl.h>
  #include <linux/sched.h>
  #include <linux/slab.h>
  
  #include "ctree.h"
  #include "btrfs_inode.h"
  #include "xattr.h"
  
  struct posix_acl *btrfs_get_acl(struct inode *inode, int type)
  {
  	int size;
  	const char *name;
  	char *value = NULL;
  	struct posix_acl *acl;
  
  	switch (type) {
  	case ACL_TYPE_ACCESS:
  		name = POSIX_ACL_XATTR_ACCESS;
  		break;
  	case ACL_TYPE_DEFAULT:
  		name = POSIX_ACL_XATTR_DEFAULT;
  		break;
  	default:
  		BUG();
  	}
  
  	size = __btrfs_getxattr(inode, name, "", 0);
  	if (size > 0) {
  		value = kzalloc(size, GFP_NOFS);
  		if (!value)
  			return ERR_PTR(-ENOMEM);
  		size = __btrfs_getxattr(inode, name, value, size);
  	}
  	if (size > 0) {
  		acl = posix_acl_from_xattr(&init_user_ns, value, size);
  	} else if (size == -ENOENT || size == -ENODATA || size == 0) {
  		/* FIXME, who returns -ENOENT?  I think nobody */
  		acl = NULL;
  	} else {
  		acl = ERR_PTR(-EIO);
  	}
  	kfree(value);
  
  	if (!IS_ERR(acl))
  		set_cached_acl(inode, type, acl);
  
  	return acl;
  }
  
  /*
   * Needs to be called with fs_mutex held
   */
  static int __btrfs_set_acl(struct btrfs_trans_handle *trans,
  			 struct inode *inode, struct posix_acl *acl, int type)
  {
  	int ret, size = 0;
  	const char *name;
  	char *value = NULL;
  
  	if (acl) {
  		ret = posix_acl_valid(acl);
  		if (ret < 0)
  			return ret;
  		ret = 0;
  	}
  
  	switch (type) {
  	case ACL_TYPE_ACCESS:
  		name = POSIX_ACL_XATTR_ACCESS;
  		if (acl) {
  			ret = posix_acl_equiv_mode(acl, &inode->i_mode);
  			if (ret < 0)
  				return ret;
  			if (ret == 0)
  				acl = NULL;
  		}
  		ret = 0;
  		break;
  	case ACL_TYPE_DEFAULT:
  		if (!S_ISDIR(inode->i_mode))
  			return acl ? -EINVAL : 0;
  		name = POSIX_ACL_XATTR_DEFAULT;
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	if (acl) {
  		size = posix_acl_xattr_size(acl->a_count);
  		value = kmalloc(size, GFP_NOFS);
  		if (!value) {
  			ret = -ENOMEM;
  			goto out;
  		}
  
  		ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
  		if (ret < 0)
  			goto out;
  	}
  
  	ret = __btrfs_setxattr(trans, inode, name, value, size, 0);
  out:
  	kfree(value);
  
  	if (!ret)
  		set_cached_acl(inode, type, acl);
  
  	return ret;
  }
  
  int btrfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
  {
  	return __btrfs_set_acl(NULL, inode, acl, type);
  }
  
  /*
   * btrfs_init_acl is already generally called under fs_mutex, so the locking
   * stuff has been fixed to work with that.  If the locking stuff changes, we
   * need to re-evaluate the acl locking stuff.
   */
  int btrfs_init_acl(struct btrfs_trans_handle *trans,
  		   struct inode *inode, struct inode *dir)
  {
  	struct posix_acl *default_acl, *acl;
  	int ret = 0;
  
  	/* this happens with subvols */
  	if (!dir)
  		return 0;
  
  	ret = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
  	if (ret)
  		return ret;
  
  	if (default_acl) {
  		ret = __btrfs_set_acl(trans, inode, default_acl,
  				      ACL_TYPE_DEFAULT);
  		posix_acl_release(default_acl);
  	}
  
  	if (acl) {
  		if (!ret)
  			ret = __btrfs_set_acl(trans, inode, acl,
  					      ACL_TYPE_ACCESS);
  		posix_acl_release(acl);
  	}
  
  	if (!default_acl && !acl)
  		cache_no_acl(inode);
  	return ret;
  }