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Subject: Re: bcachefs - snapshots
To:     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>
From:   Bernd Schubert <bernd.schubert@fastmail.fm>
Message-ID: <dbe56ac2-22bd-74d5-ab5d-9f6673884212@fastmail.fm>
Date:   Mon, 27 Sep 2021 15:06:45 +0200
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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)

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?