On Thu, Apr 12, 2018 at 05:08:04PM +0200, Miklos Szeredi wrote:
> Implement stacked fsync().
> 
> Signed-off-by: Miklos Szeredi <mszer...@redhat.com>
> ---
>  fs/overlayfs/file.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
> index b98204c1c19c..4417527667ff 100644
> --- a/fs/overlayfs/file.c
> +++ b/fs/overlayfs/file.c
> @@ -222,10 +222,30 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, 
> struct iov_iter *iter)
>       return ret;
>  }
>  
> +static int ovl_fsync(struct file *file, loff_t start, loff_t end, int 
> datasync)
> +{
> +     struct fd real;
> +     const struct cred *old_cred;
> +     int ret;
> +
> +     ret = ovl_real_file(file, &real);
> +     if (ret)
> +             return ret;
> +
> +     old_cred = ovl_override_creds(file_inode(file)->i_sb);
> +     ret = vfs_fsync_range(real.file, start, end, datasync);
> +     revert_creds(old_cred);

Can we avoid calling fsync() on real file if it is not upper. Is it worth
optimizing.

Vivek

> +
> +     fdput(real);
> +
> +     return ret;
> +}
> +
>  const struct file_operations ovl_file_operations = {
>       .open           = ovl_open,
>       .release        = ovl_release,
>       .llseek         = ovl_llseek,
>       .read_iter      = ovl_read_iter,
>       .write_iter     = ovl_write_iter,
> +     .fsync          = ovl_fsync,
>  };
> -- 
> 2.14.3
> 
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