On Mon, Aug 27, 2018 at 03:56:04PM +0300, Amir Goldstein wrote:
> Implement stacked fadvise to fix syscalls readahead(2) and fadvise64(2)
> on an overlayfs file.
>
> Suggested-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
> Fixes: d1d04ef8572b ("ovl: stack file ops")
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> fs/overlayfs/file.c | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
> index a4acd84591d4..42d2d034d85c 100644
> --- a/fs/overlayfs/file.c
> +++ b/fs/overlayfs/file.c
> @@ -331,6 +331,23 @@ static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len
> return ret;
> }
>
> +int ovl_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
> +{
> + struct fd real;
> + int ret;
> +
> + ret = ovl_real_fdget(file, &real);
> + if (ret)
> + return ret;
> +
> + /* XXX: do we need mounter credentials? */
Given we are switching creds to mounter for rest of the file operations,
so I would think we need to do it here as well to be consistent with
this security model.
Thanks
Vivek
> + ret = vfs_fadvise(real.file, offset, len, advice);
> +
> + fdput(real);
> +
> + return ret;
> +}
> +
> static long ovl_real_ioctl(struct file *file, unsigned int cmd,
> unsigned long arg)
> {
> @@ -499,6 +516,7 @@ const struct file_operations ovl_file_operations = {
> .fsync = ovl_fsync,
> .mmap = ovl_mmap,
> .fallocate = ovl_fallocate,
> + .fadvise = ovl_fadvise,
> .unlocked_ioctl = ovl_ioctl,
> .compat_ioctl = ovl_compat_ioctl,
>
> --
> 2.7.4
>
