Re: [PATCH] btrfs: super.c: Set compress_level=0 when using compress=lzo

[David Sterba <dsterba@suse.cz>]

On Mon, Aug 03, 2020 at 04:55:01PM -0300, Marcos Paulo de Souza wrote:
> From: Marcos Paulo de Souza <mpdesouza@suse.com>
> 
> Currently a user can set mount "-o compress" which will set the
> compression algorithm to zlib, and use the default compress level for
> zlib (3):
> 
> relatime,compress=zlib:3,space_cache
> 
> If the user remounts the fs using "-o compress=lzo", then the old
> compress_level is used:
> 
> relatime,compress=lzo:3,space_cache
> 
> But lzo does not exposes any tunable compress level. The same happens if we set
> any compress argument with different level, even with zstd.
> 
> Fix this issue by resetting the compress_level when compress=lzo is specified.
> With the fix applied, lzo is shown without compress level, even after remounting
> from zlib or zstd:
> 
> relatime,compress=lzo,space_cache
> 
> Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
> ---
> 
>  I found this issue while testing mount options. Should we tag this fix for
>  stable since the introduction of the compress_level, or is it no worthy?

I'll tag it for stable, it's user-visible and confusing. Thanks.