Re: [PATCH] btrfs-progs: hide block group tree behind experimental feature

[David Sterba <dsterba@suse.cz>]

On Thu, Sep 22, 2022 at 06:20:25AM +0800, Qu Wenruo wrote:
> 
> 
> On 2022/9/21 22:06, David Sterba wrote:
> > On Mon, Sep 12, 2022 at 11:12:01AM +0800, Qu Wenruo wrote:
> >> The block group tree doesn't yet have full bi-directional conversion
> >> support from btrfstune, and it seems we may want one or two release
> >> cycles to rule out some extra bugs before really releasing the progs
> >> support.
> >>
> >> This patch will hide the block group tree feature behind experimental
> >> flag for the following tools:
> >>
> >> - btrfstune
> >>    "-b" option to convert to bg tree.
> >>
> >> - mkfs.btrfs
> >>    hide "block-group-tree" feature from both -O (the new default position
> >>    for all features) and -R (the old, soon to be deprecated one).
> >
> > The block group tree is going to 6.1, so the progs support will be
> > experimental in 6.0 and enabled no later than 6.1. It might be enabled
> > earlier so we can use the normal build in testing.
> 
> Personally speaking, I'd hope bg tree would be hidden behind
> experimental until the bi-directional convert is implemented.

As with other new features we need a stabilization period, mkfs support
is the first step and the user space tools should provide feature parity
in the same release number at the latest.

That we have the btrfstune to do the conversions is a nice to have that
we do want to have eventually because we know that the bg tree will
solve slow mounts on large filesystems. So the experimental status for
btrfstune is fine, but not for mkfs.