linux-imx

/*

 * Copyright (C) 2017 Red Hat, Inc.

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 as published by

 * the Free Software Foundation.

 */

​

#include <linux/cred.h>

#include <linux/file.h>

#include <linux/mount.h>

#include <linux/xattr.h>

#include <linux/uio.h>

#include "overlayfs.h"

​

static char ovl_whatisit(struct inode *inode, struct inode *realinode)

{

    if (realinode != ovl_inode_upper(inode))

        return 'l';

    if (ovl_has_upperdata(inode))

        return 'u';

    else

        return 'm';

}

​

static struct file *ovl_open_realfile(const struct file *file,

                      struct inode *realinode)

{

    struct inode *inode = file_inode(file);

    struct file *realfile;

    const struct cred *old_cred;

​

    old_cred = ovl_override_creds(inode->i_sb);

    realfile = open_with_fake_path(&file->f_path, file->f_flags | O_NOATIME,

                       realinode, current_cred());

    revert_creds(old_cred);

​

    pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n",

         file, file, ovl_whatisit(inode, realinode), file->f_flags,

         realfile, IS_ERR(realfile) ? 0 : realfile->f_flags);

​

    return realfile;

}

​

#define OVL_SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT)

​

static int ovl_change_flags(struct file *file, unsigned int flags)

{

    struct inode *inode = file_inode(file);

    int err;

​

    /* No atime modificaton on underlying */

    flags |= O_NOATIME;

​

    /* If some flag changed that cannot be changed then something's amiss */

    if (WARN_ON((file->f_flags ^ flags) & ~OVL_SETFL_MASK))

        return -EIO;

​

    flags &= OVL_SETFL_MASK;

​

    if (((flags ^ file->f_flags) & O_APPEND) && IS_APPEND(inode))

        return -EPERM;

​

    if (flags & O_DIRECT) {

        if (!file->f_mapping->a_ops ||

            !file->f_mapping->a_ops->direct_IO)

            return -EINVAL;

    }

​

    if (file->f_op->check_flags) {

        err = file->f_op->check_flags(flags);

        if (err)

            return err;

    }

​

    spin_lock(&file->f_lock);

    file->f_flags = (file->f_flags & ~OVL_SETFL_MASK) | flags;

    spin_unlock(&file->f_lock);

​

    return 0;

}

​

static int ovl_real_fdget_meta(const struct file *file, struct fd *real,

                   bool allow_meta)

{

    struct inode *inode = file_inode(file);

    struct inode *realinode;

​

    real->flags = 0;

    real->file = file->private_data;

​

    if (allow_meta)