linux-kernel - Re: [PATCH v3 13/13] bcachefs: fiemap: emit new COMPRESSED state

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Date: Fri, 5 Apr 2024 13:34:00 -0600
From: Andreas Dilger <adilger@...ger.ca>
To: Sweet Tea Dorminy <sweettea-kernel@...miny.me>,
 Kent Overstreet <kent.overstreet@...ux.dev>
Cc: Jonathan Corbet <corbet@....net>,
 Brian Foster <bfoster@...hat.com>,
 Chris Mason <clm@...com>,
 Josef Bacik <josef@...icpanda.com>,
 David Sterba <dsterba@...e.com>,
 Jaegeuk Kim <jaegeuk@...nel.org>,
 Chao Yu <chao@...nel.org>,
 Alexander Viro <viro@...iv.linux.org.uk>,
 Christian Brauner <brauner@...nel.org>,
 Jan Kara <jack@...e.cz>,
 Mickaël Salaün <mic@...ikod.net>,
 linux-doc@...r.kernel.org,
 Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
 linux-bcachefs@...r.kernel.org,
 linux-btrfs <linux-btrfs@...r.kernel.org>,
 linux-f2fs-devel@...ts.sourceforge.net,
 linux-fsdevel <linux-fsdevel@...r.kernel.org>,
 kernel-team@...a.com
Subject: Re: [PATCH v3 13/13] bcachefs: fiemap: emit new COMPRESSED state


> On Apr 5, 2024, at 1:17 PM, Andreas Dilger <adilger@...ger.ca> wrote:
> 
> On Apr 3, 2024, at 1:22 AM, Sweet Tea Dorminy <sweettea-kernel@...miny.me> wrote:
>> 
>> Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@...miny.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.

Ah, I missed the 11/13 patch that is handling up most of the bcachefs
phys_len changes.  I think this should be folded into that patch so
it is clear to the callers that the data is compressed when they see
fe_physical_length is not the same as fe_logical_length.

Cheers, Andreas






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