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Date: Sat, 6 Apr 2024 01:20:46 -0400
From: Kent Overstreet <kent.overstreet@linux.dev>
To: Andreas Dilger <adilger@dilger.ca>
Cc: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>, 
	Jonathan Corbet <corbet@lwn.net>, Brian Foster <bfoster@redhat.com>, Chris Mason <clm@fb.com>, 
	Josef Bacik <josef@toxicpanda.com>, David Sterba <dsterba@suse.com>, 
	Jaegeuk Kim <jaegeuk@kernel.org>, Chao Yu <chao@kernel.org>, 
	Alexander Viro <viro@zeniv.linux.org.uk>, Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>, 
	=?utf-8?Q?Micka=C3=ABl_Sala=C3=BCn?= <mic@digikod.net>, linux-doc@vger.kernel.org, 
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, linux-bcachefs@vger.kernel.org, 
	linux-btrfs <linux-btrfs@vger.kernel.org>, linux-f2fs-devel@lists.sourceforge.net, 
	linux-fsdevel <linux-fsdevel@vger.kernel.org>, kernel-team@meta.com
Subject: Re: [PATCH v3 13/13] bcachefs: fiemap: emit new COMPRESSED state
Message-ID: <2iyoi665o6hogzzlfhs6ets6vq2joh4xi5t3fbcpdmlv2cyrxu@7umadxpnaql7>
References: <cover.1712126039.git.sweettea-kernel@dorminy.me>
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 <7CF0A3D0-50E7-448F-A992-90B9168D557F@dilger.ca>
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In-Reply-To: <7CF0A3D0-50E7-448F-A992-90B9168D557F@dilger.ca>

On Fri, Apr 05, 2024 at 01:17:45PM -0600, Andreas Dilger wrote:
> On Apr 3, 2024, at 1:22 AM, Sweet Tea Dorminy <sweettea-kernel@dorminy.me> wrote:
> > 
> > Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
> > ---
> > fs/bcachefs/fs.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/fs/bcachefs/fs.c b/fs/bcachefs/fs.c
> > index d2793bae842d..54f613f977b4 100644
> > --- a/fs/bcachefs/fs.c
> > +++ b/fs/bcachefs/fs.c
> > @@ -921,7 +921,7 @@ static int bch2_fill_extent(struct bch_fs *c,
> > 				flags2 |= FIEMAP_EXTENT_UNWRITTEN;
> > 
> > 			if (p.crc.compression_type) {
> > -				flags2 |= FIEMAP_EXTENT_ENCODED;
> > +				flags2 |= FIEMAP_EXTENT_DATA_COMPRESSED;
> 
> (defect) This should *also* set FIEMAP_EXTENT_ENCODED in this case,
> along with FIEMAP_EXTENT_DATA_COMPRESSED.  Both for compatibility with
> older code that doesn't understand FIEMAP_EXTENT_DATA_COMPRESSED, and
> because the data still cannot be read directly from the volume when it
> is not mounted.
> 
> Probably Kent should chime in here with what needs to be done to set
> the phys_len properly for bcachefs, or leave this patch out of your
> series and let him submit it directly.  With proposed wrapper in the
> first patch of the series there isn't a hard requirement to change
> all of the filesystems in one shot.

You get phys len from crc.compressed_size - that's always guaranteed,
even if it's not compressed