Re: [PATCH RFC 02/41] nvmet: check that the file backend supports ->{read,write}_iter

[Jan Kara <jack@xxxxxxx>]

On Tue 10-11-26 10:14:18, Christian Brauner wrote:
> The file backend calls ->read_iter() and ->write_iter() of the backing
> file directly but never checks that they exist. Everything that isn't a
> block device ends up in the file backend. So a namespace pointing to a
> file without them calls a NULL pointer on its first I/O. Only
> buffered_io=1 gets that far as the O_DIRECT open fails for such files.
> 
> Refuse them when the namespace is enabled the same way zloop does since
> commit 0c10f8a1a7ae ("zloop: check that the zone backing file support
> ->{read,write}_iter").
> 
> Fixes: d5eff33ee6f8 ("nvmet: add simple file backed ns support")
> Signed-off-by: Christian Brauner (Amutable) <brauner@xxxxxxxxxx>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

                                                                Honza

> ---
>  drivers/nvme/target/io-cmd-file.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/nvme/target/io-cmd-file.c 
> b/drivers/nvme/target/io-cmd-file.c
> index 695963dd932e..dfa8aa46188c 100644
> --- a/drivers/nvme/target/io-cmd-file.c
> +++ b/drivers/nvme/target/io-cmd-file.c
> @@ -47,6 +47,11 @@ int nvmet_file_ns_enable(struct nvmet_ns *ns)
>               return ret;
>       }
>  
> +     if (!ns->file->f_op->read_iter || !ns->file->f_op->write_iter) {
> +             ret = -EINVAL;
> +             goto err;
> +     }
> +
>       nvmet_file_ns_revalidate(ns);
>  
>       /*
> 
> -- 
> 2.53.0
> 
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR