linux-kernel - Re: [PATCH] btrfs/defrag: implement compression levels

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Message-ID: <20250305070521.GZ5777@suse.cz>
Date: Wed, 5 Mar 2025 08:05:21 +0100
From: David Sterba <dsterba@...e.cz>
To: Daniel Vacek <neelx@...e.com>
Cc: Qu Wenruo <quwenruo.btrfs@....com>, Chris Mason <clm@...com>,
	Josef Bacik <josef@...icpanda.com>, David Sterba <dsterba@...e.com>,
	linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] btrfs/defrag: implement compression levels

On Wed, Mar 05, 2025 at 08:02:28AM +0100, Daniel Vacek wrote:
> > > @@ -1376,10 +1377,19 @@ int btrfs_defrag_file(struct inode *inode, struct file_ra_state *ra,
> > >               return -EINVAL;
> > >
> > >       if (do_compress) {
> > > -             if (range->compress_type >= BTRFS_NR_COMPRESS_TYPES)
> > > -                     return -EINVAL;
> > > -             if (range->compress_type)
> > > -                     compress_type = range->compress_type;
> > > +             if (range->flags & BTRFS_DEFRAG_RANGE_COMPRESS_LEVEL) {
> > > +                     if (range->compress.type >= BTRFS_NR_COMPRESS_TYPES)
> > > +                             return -EINVAL;
> > > +                     if (range->compress.type) {
> > > +                             compress_type = range->compress.type;
> > > +                             compress_level= range->compress.level;
> > > +                     }
> >
> > I am not familiar with the compress level, but
> > btrfs_compress_set_level() does extra clamping, maybe we also want to do
> > that too?
> 
> This is intentionally left to be limited later. There's no need to do
> it at this point and the code is simpler. It's also compression
> type/method agnostic.

This is input parameter validation so we should not postpone it until
the whole process starts. The complexity can be wrapped in helpers, we
already have that for various purposes like
compression_decompress_bio().