Bug#865462: extlinux: boot from gpt partition with Btrfs does not work

[Peter Colberg <peter@colberg.org>]

Control: tags -1 patch upstream fixed-upstream stretch
Control: retitle -1 extlinux: fails to boot from Btrfs filesystem

Dear Maintainer,

I can confirm that this upstream commit fixes booting from BTRFS:

commit 548386049cd41e887079cdb904d3954365eb28f3
Author: Paulo Alcantara <pcacjr@zytor.com>
Date:   Thu Dec 24 01:48:13 2015 -0200

    btrfs: Fix logical to physical block address mapping
    
    The current btrfs support did not handled multiple stripes stored in
    chunk items, hence skipping the physical addresses that were needed to
    do the mapping.
    
    Besides, the chunk tree may contain DEV_ITEM keys which store
    information on all of the underlying block devices, so we must skip them
    instead of finishing lookup.
    
    The bug was reproduced with btrfs-progs v4.2.2.
    
    Cc: Gene Cumm <gene.cumm@gmail.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Signed-off-by: Paulo Alcantara <pcacjr@zytor.com>
    ---
    v1 -> v2:
     * Do not set ignore_key multiple times. Set it before parsing chunk
       tree.
    v2 -> v3:
     * Replace an unnecessary goto with a continue statement.


Could you include the patch in the next stable point release?

Regards,
Peter