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

Oleg Nesterov
2016-08-30T14:33:50Z

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?

Oleg.