LXR linux/fs/btrfs/acl.c

   1/*
   2 * Copyright (C) 2007 Red Hat.  All rights reserved.
   3 *
   4 * This program is free software; you can redistribute it and/or
   5 * modify it under the terms of the GNU General Public
   6 * License v2 as published by the Free Software Foundation.
   7 *
   8 * This program is distributed in the hope that it will be useful,
   9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11 * General Public License for more details.
  12 *
  13 * You should have received a copy of the GNU General Public
  14 * License along with this program; if not, write to the
  15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16 * Boston, MA 021110-1307, USA.
  17 */
  18
  19#include <linux/fs.h>
  20#include <linux/string.h>
  21#include <linux/xattr.h>
  22#include <linux/posix_acl_xattr.h>
  23#include <linux/posix_acl.h>
  24#include <linux/sched.h>
  25#include <linux/slab.h>
  26
  27#include "ctree.h"
  28#include "btrfs_inode.h"
  29#include "xattr.h"
  30
  31struct posix_acl *btrfs_get_acl(struct inode *inode, int type)
  32{
  33        int size;
  34        const char *name;
  35        char *value = NULL;
  36        struct posix_acl *acl;
  37
  38        switch (type) {
  39        case ACL_TYPE_ACCESS:
  40                name = POSIX_ACL_XATTR_ACCESS;
  41                break;
  42        case ACL_TYPE_DEFAULT:
  43                name = POSIX_ACL_XATTR_DEFAULT;
  44                break;
  45        default:
  46                BUG();
  47        }
  48
  49        size = __btrfs_getxattr(inode, name, "", 0);
  50        if (size > 0) {
  51                value = kzalloc(size, GFP_NOFS);
  52                if (!value)
  53                        return ERR_PTR(-ENOMEM);
  54                size = __btrfs_getxattr(inode, name, value, size);
  55        }
  56        if (size > 0) {
  57                acl = posix_acl_from_xattr(&init_user_ns, value, size);
  58        } else if (size == -ENOENT || size == -ENODATA || size == 0) {
  59                /* FIXME, who returns -ENOENT?  I think nobody */
  60                acl = NULL;
  61        } else {
  62                acl = ERR_PTR(-EIO);
  63        }
  64        kfree(value);
  65
  66        if (!IS_ERR(acl))
  67                set_cached_acl(inode, type, acl);
  68
  69        return acl;
  70}
  71
  72/*
  73 * Needs to be called with fs_mutex held
  74 */
  75static int __btrfs_set_acl(struct btrfs_trans_handle *trans,
  76                         struct inode *inode, struct posix_acl *acl, int type)
  77{
  78        int ret, size = 0;
  79        const char *name;
  80        char *value = NULL;
  81
  82        switch (type) {
  83        case ACL_TYPE_ACCESS:
  84                name = POSIX_ACL_XATTR_ACCESS;
  85                if (acl) {
  86                        ret = posix_acl_equiv_mode(acl, &inode->i_mode);
  87                        if (ret < 0)
  88                                return ret;
  89                        if (ret == 0)
  90                                acl = NULL;
  91                }
  92                ret = 0;
  93                break;
  94        case ACL_TYPE_DEFAULT:
  95                if (!S_ISDIR(inode->i_mode))
  96                        return acl ? -EINVAL : 0;
  97                name = POSIX_ACL_XATTR_DEFAULT;
  98                break;
  99        default:
 100                return -EINVAL;
 101        }
 102
 103        if (acl) {
 104                size = posix_acl_xattr_size(acl->a_count);
 105                value = kmalloc(size, GFP_NOFS);
 106                if (!value) {
 107                        ret = -ENOMEM;
 108                        goto out;
 109                }
 110
 111                ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
 112                if (ret < 0)
 113                        goto out;
 114        }
 115
 116        ret = __btrfs_setxattr(trans, inode, name, value, size, 0);
 117out:
 118        kfree(value);
 119
 120        if (!ret)
 121                set_cached_acl(inode, type, acl);
 122
 123        return ret;
 124}
 125
 126int btrfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 127{
 128        return __btrfs_set_acl(NULL, inode, acl, type);
 129}
 130
 131/*
 132 * btrfs_init_acl is already generally called under fs_mutex, so the locking
 133 * stuff has been fixed to work with that.  If the locking stuff changes, we
 134 * need to re-evaluate the acl locking stuff.
 135 */
 136int btrfs_init_acl(struct btrfs_trans_handle *trans,
 137                   struct inode *inode, struct inode *dir)
 138{
 139        struct posix_acl *default_acl, *acl;
 140        int ret = 0;
 141
 142        /* this happens with subvols */
 143        if (!dir)
 144                return 0;
 145
 146        ret = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 147        if (ret)
 148                return ret;
 149
 150        if (default_acl) {
 151                ret = __btrfs_set_acl(trans, inode, default_acl,
 152                                      ACL_TYPE_DEFAULT);
 153                posix_acl_release(default_acl);
 154        }
 155
 156        if (acl) {
 157                if (!ret)
 158                        ret = __btrfs_set_acl(trans, inode, acl,
 159                                              ACL_TYPE_ACCESS);
 160                posix_acl_release(acl);
 161        }
 162
 163        if (!default_acl && !acl)
 164                cache_no_acl(inode);
 165        return ret;
 166}
 167