Re: [RFC 0/2] erofs: introduce bloom filter for xattr

[Gao Xiang]

On 2023/7/4 16:05, Alexander Larsson wrote:
> On Tue, Jul 4, 2023 at 7:56 AM Jingbo Xu <jefflexu@xxxxxxxxxxxxxxxxx> wrote:
> >

...

> > ```
> > seed: 25bbe08f
> > bit 31: trusted.overlay.metacopy, user.overlay.metacopy,
> >
> > seed: cc922efd
> > bit  3: trusted.overlay.opaque, user.overlay.opaque,
> >
> > seed: cd478c17
> > bit  6: trusted.overlay.metacopy, user.overlay.metacopy,
> > ```
> >
> >
> > Any other idea?
>
> Any of these three is good to me. I don't have any ideas directly
> related to this. However,  semi-related, it would be really cool if
> fuse supported the same approach for xattr lookup. I.e. if lookup
> could add a bloom filter value as part of the inode data, then we
> could avoid a kernel<->fusefs-d transition for negative xattrs
> lookups.

I think we could just use a hardcoded magic number (e.g. 25bbe08f)
as a start first, since it seems already fulfill our requirement
and it's a compatible feature (and the implementation is also not
complex.)  So I'm not quite worried about this.

Thanks,
Gao Xiang

>