Re: [PATCH 3/8] bdi: add a ->dev_name field to struct backing_dev_info

[Hans de Goede]

Hi,

On 4/20/20 1:58 PM, Christoph Hellwig wrote:
> On Mon, Apr 20, 2020 at 01:41:57PM +0200, Hans de Goede wrote:
> > AFAICT for vboxsf the bdi-name can be anything as long as it is unique, hence
> > the "vboxsf-" prefix to make this unique vs other block-devices and the
> > ".%d" postfix is necessary because the same export can be mounted multiple
> > times (without using bind mounts), see:
> > https://github.com/jwrdegoede/vboxsf/issues/3
>
> Shouldn't vboxsf switch to get_tree_single instead of get_tree_nodev?
> Having two independent dentry trees for a single actual file system
> can be pretty dangerous.

That is a good point I will look into this.

> > The presence of the source inside the bdi-name is only for informational
> > purposes really, so truncating that should be fine, maybe switch to:
> >
> > "vboxsf%d-%s" as format string and swap the sbi->bdi_id and fc->source
> > in the args, then if we truncate anything it will be the source (which
> > as said is only there for informational purposes) and the name will
> > still be guaranteed to be unique.
>
> Can we just switch to vboxsf%d where %d Ñs a simple monotonically
> incrementing count?  That is what various other file systems (e.g. ceph)
> do.

Yes that is fine with me.

Regards,

Hans