Re: [PATCH RFC 36/41] nvmet: refuse files on pseudo filesystems as namespace backing files

[Bui Nguyen Nhu Quynh <kaylovefoss@xxxxxxxxx>]

On 11/10/2026 4:14 PM, Christian Brauner wrote:
> The file backend takes any path that isn't a block device. With
> buffered_io=1 that includes files on procfs or sysfs which then get read
> and written by a kernel worker on behalf of the host. Refuse files on
> pseudo filesystems just like loop does.
> 
> Signed-off-by: Christian Brauner (Amutable) <brauner@xxxxxxxxxx>
> ---
>  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 dfa8aa46188c..71c69bac5394 100644
> --- a/drivers/nvme/target/io-cmd-file.c
> +++ b/drivers/nvme/target/io-cmd-file.c
> @@ -52,6 +52,11 @@ int nvmet_file_ns_enable(struct nvmet_ns *ns)
>               goto err;
>       }
>  
> +     if (file_is_pseudo(ns->file)) {
> +             ret = -EINVAL;
> +             goto err;
> +     }
> +
>       nvmet_file_ns_revalidate(ns);
>  
>       /*
> 

I noticed patch 41/41 doesn't include a test for nvmet. Would it make
sense to add one with buffered_io=1? The test would need a pseudo file
that can be opened with O_RDWR and supports both read_iter and
write_iter. Otherwise, it could pass without ever reaching the new
file_is_pseudo() check.

Thanks.