linux/fs/btrfs/acl.c
Liu Bo 755ac67f83 Btrfs: skip adding an acl attribute if we don't have to
If the acl can be exactly represented in the traditional file
mode permission bits, we don't set another acl attribute.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:15 -05:00

280 lines
5.8 KiB
C

/*
* 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;
if (!IS_POSIXACL(inode))
return NULL;
acl = get_cached_acl(inode, type);
if (acl != ACL_NOT_CACHED)
return 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;
}
static int btrfs_xattr_acl_get(struct dentry *dentry, const char *name,
void *value, size_t size, int type)
{
struct posix_acl *acl;
int ret = 0;
if (!IS_POSIXACL(dentry->d_inode))
return -EOPNOTSUPP;
acl = btrfs_get_acl(dentry->d_inode, type);
if (IS_ERR(acl))
return PTR_ERR(acl);
if (acl == NULL)
return -ENODATA;
ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
posix_acl_release(acl);
return ret;
}
/*
* 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;
}
static int btrfs_xattr_acl_set(struct dentry *dentry, const char *name,
const void *value, size_t size, int flags, int type)
{
int ret;
struct posix_acl *acl = NULL;
if (!inode_owner_or_capable(dentry->d_inode))
return -EPERM;
if (!IS_POSIXACL(dentry->d_inode))
return -EOPNOTSUPP;
if (value) {
acl = posix_acl_from_xattr(&init_user_ns, value, size);
if (IS_ERR(acl))
return PTR_ERR(acl);
if (acl) {
ret = posix_acl_valid(acl);
if (ret)
goto out;
}
}
ret = btrfs_set_acl(NULL, dentry->d_inode, acl, type);
out:
posix_acl_release(acl);
return ret;
}
/*
* 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 *acl = NULL;
int ret = 0;
/* this happens with subvols */
if (!dir)
return 0;
if (!S_ISLNK(inode->i_mode)) {
if (IS_POSIXACL(dir)) {
acl = btrfs_get_acl(dir, ACL_TYPE_DEFAULT);
if (IS_ERR(acl))
return PTR_ERR(acl);
}
if (!acl)
inode->i_mode &= ~current_umask();
}
if (IS_POSIXACL(dir) && acl) {
if (S_ISDIR(inode->i_mode)) {
ret = btrfs_set_acl(trans, inode, acl,
ACL_TYPE_DEFAULT);
if (ret)
goto failed;
}
ret = posix_acl_create(&acl, GFP_NOFS, &inode->i_mode);
if (ret < 0)
return ret;
if (ret > 0) {
/* we need an acl */
ret = btrfs_set_acl(trans, inode, acl, ACL_TYPE_ACCESS);
} else {
cache_no_acl(inode);
}
} else {
cache_no_acl(inode);
}
failed:
posix_acl_release(acl);
return ret;
}
int btrfs_acl_chmod(struct inode *inode)
{
struct posix_acl *acl;
int ret = 0;
if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
if (!IS_POSIXACL(inode))
return 0;
acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
if (IS_ERR_OR_NULL(acl))
return PTR_ERR(acl);
ret = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
if (ret)
return ret;
ret = btrfs_set_acl(NULL, inode, acl, ACL_TYPE_ACCESS);
posix_acl_release(acl);
return ret;
}
const struct xattr_handler btrfs_xattr_acl_default_handler = {
.prefix = POSIX_ACL_XATTR_DEFAULT,
.flags = ACL_TYPE_DEFAULT,
.get = btrfs_xattr_acl_get,
.set = btrfs_xattr_acl_set,
};
const struct xattr_handler btrfs_xattr_acl_access_handler = {
.prefix = POSIX_ACL_XATTR_ACCESS,
.flags = ACL_TYPE_ACCESS,
.get = btrfs_xattr_acl_get,
.set = btrfs_xattr_acl_set,
};