linux-imx

/*

 * Copyright (C) 2002,2003 by Andreas Gruenbacher <a.gruenbacher@computer.org>

 *

 * Fixes from William Schumacher incorporated on 15 March 2001.

 *    (Reported by Charles Bertsch, <CBertsch@microtest.com>).

 */

​

/*

 *  This file contains generic functions for manipulating

 *  POSIX 1003.1e draft standard 17 ACLs.

 */

​

#include <linux/kernel.h>

#include <linux/slab.h>

#include <linux/atomic.h>

#include <linux/fs.h>

#include <linux/sched.h>

#include <linux/cred.h>

#include <linux/posix_acl.h>

#include <linux/posix_acl_xattr.h>

#include <linux/xattr.h>

#include <linux/export.h>

#include <linux/user_namespace.h>

​

static struct posix_acl **acl_by_type(struct inode *inode, int type)

{

    switch (type) {

    case ACL_TYPE_ACCESS:

        return &inode->i_acl;

    case ACL_TYPE_DEFAULT:

        return &inode->i_default_acl;

    default:

        BUG();

    }

}

​

struct posix_acl *get_cached_acl(struct inode *inode, int type)

{

    struct posix_acl **p = acl_by_type(inode, type);

    struct posix_acl *acl;

​

    for (;;) {

        rcu_read_lock();

        acl = rcu_dereference(*p);

        if (!acl || is_uncached_acl(acl) ||

            refcount_inc_not_zero(&acl->a_refcount))

            break;

        rcu_read_unlock();

        cpu_relax();

    }

    rcu_read_unlock();

    return acl;

}

EXPORT_SYMBOL(get_cached_acl);

​

struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type)

{

    return rcu_dereference(*acl_by_type(inode, type));

}

EXPORT_SYMBOL(get_cached_acl_rcu);

​

void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl)

{

    struct posix_acl **p = acl_by_type(inode, type);

    struct posix_acl *old;

​

    old = xchg(p, posix_acl_dup(acl));

    if (!is_uncached_acl(old))

        posix_acl_release(old);

}

EXPORT_SYMBOL(set_cached_acl);

​

static void __forget_cached_acl(struct posix_acl **p)

{

    struct posix_acl *old;

​

    old = xchg(p, ACL_NOT_CACHED);

    if (!is_uncached_acl(old))

        posix_acl_release(old);

}

​

void forget_cached_acl(struct inode *inode, int type)

{

    __forget_cached_acl(acl_by_type(inode, type));

}

EXPORT_SYMBOL(forget_cached_acl);

​

void forget_all_cached_acls(struct inode *inode)

{

    __forget_cached_acl(&inode->i_acl);

    __forget_cached_acl(&inode->i_default_acl);

}