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

[Kent Overstreet]

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@xxxxxxxxxx> wrote:
> > 
> > Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@xxxxxxxxxx>
> > ---
> > 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