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From:   "Frank Filz" <ffilzlnx@mindspring.com>
To:     "'Bernd Schubert'" <bernd.schubert@fastmail.fm>,
        "'Kent Overstreet'" <kent.overstreet@gmail.com>,
        <linux-kernel@vger.kernel.org>, <linux-bcachefs@vger.kernel.org>,
        <linux-fsdevel@vger.kernel.org>
References: <YVEjEwCiqje7yDyV@moria.home.lan> <dbe56ac2-22bd-74d5-ab5d-9f6673884212@fastmail.fm>
In-Reply-To: <dbe56ac2-22bd-74d5-ab5d-9f6673884212@fastmail.fm>
Subject: RE: bcachefs - snapshots
Date:   Mon, 27 Sep 2021 09:43:19 -0700
Message-ID: <000901d7b3be$c7783120$56689360$@mindspring.com>
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> On 9/27/21 3:49 AM, Kent Overstreet wrote:
> > Snapshots have been merged! 9 months of work and 3k lines of new =
code,
> > finally released. Some highlights:
> >
> >  - btrfs style subvolumes & snapshots interface
> >  - snapshots are writeable
> >  - highly scalable: number of snapshots is limited only by your disk
> > space
> >  - highly space efficient: no internal fragmentation issues
> >
> > Design doc here: https://bcachefs.org/Snapshots/
> >
> > The core functionality is complete - snapshot creation and deletion
> > works, fsck changes are done (most of the complexity was in making
> > fsck work without O(number of snapshots) performance - tricky). =
Everything
> else is a todo item:
> >
> >  - still need to export different st_dev for files in different =
subvolumes
> >    (we'll never allocate a new inode with an inode number that =
collides with an
> >    inode inother subvolume - but snapshots will naturally result in =
colliding
> >    inode numbers)
>=20
> With my limited high level view on it - shouldn't you discuss with =
Neil about a
> solution and to avoid going the btrfs route for colliding inode =
numbers?

I was going to ask that also having been watching the btrfs subvolume =
saga. As maintainer of the Ganesha user space NFS server I have an =
interest in this also though we haven't had anyone talk about bcachefs =
yet.

Frank