linux-kernel - Re: [RFC 1/3] x86/vdso: create vdso file, use it for mapping

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Date:   Tue, 30 Aug 2016 17:53:42 +0300
From:   Dmitry Safonov <0x7f454c46@...il.com>
To:     Oleg Nesterov <oleg@...hat.com>
Cc:     Dmitry Safonov <dsafonov@...tuozzo.com>,
        linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        Andy Lutomirski <luto@...capital.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>, X86 ML <x86@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [RFC 1/3] x86/vdso: create vdso file, use it for mapping

2016-08-30 17:33 GMT+03:00 Oleg Nesterov <oleg@...hat.com>:
> On 08/25, Dmitry Safonov wrote:
>>
>> +static __init struct file *init_vdso_file(const struct vdso_image *vdso_image,
>> +                                     const char *name)
>> +{
>> +     struct super_block *sb;
>> +     struct qstr name_str;
>> +     struct inode *inode;
>> +     struct path path;
>> +     struct file *res;
>> +
>> +     if (IS_ERR(vdso_mnt))
>> +             return ERR_CAST(vdso_mnt);
>> +     sb = vdso_mnt->mnt_sb;
>> +
>> +     name_str.hash = 0;
>> +     name_str.len = strlen(name);
>> +     name_str.name = name;
>> +
>> +     res = ERR_PTR(-ENOMEM);
>> +     path.mnt = mntget(vdso_mnt);
>> +     path.dentry = d_alloc_pseudo(sb, &name_str);
>> +     if (!path.dentry)
>> +             goto put_path;
>> +     d_set_d_op(path.dentry, &vdso_dops);
>> +
>> +     res = ERR_PTR(-ENOSPC);
>> +     inode = ramfs_get_inode(sb, NULL, S_IFREG | S_IRUGO | S_IXUGO, 0);
>> +     if (!inode)
>> +             goto put_path;
>> +
>> +     inode->i_flags |= S_PRIVATE;
>> +     d_instantiate(path.dentry, inode);
>> +     inode->i_size = vdso_image->size;
>> +
>> +     res = ERR_PTR(add_vdso_pages_to_page_cache(vdso_image, inode));
>> +     if (IS_ERR(res))
>> +             goto put_path;
>> +
>> +     res = alloc_file(&path, FMODE_READ, &ramfs_file_operations);
>> +     if (!IS_ERR(res))
>> +             return res;
>> +
>> +put_path:
>> +     path_put(&path);
>> +     return res;
>> +}
>
> Not sure... I think alloc_anon_inode() makes more sense.
>
> Perhaps you can look at fs/aio.c and extract some bits of code into
> the new helpers which could be used by both aio_fs and vdso_fs?

Thanks, will do for the next version.

-- 
             Dmitry