Re: [PATCH 2/5] btrfs-progs: tune use the latest bdev in fs_devices for super_copy

[Anand Jain <anand.jain@oracle.com>]

Currently, btrfstune relies on the superblock of the device specified
in the btrfstune argument for fs_info::super_copy. However, it should
use fs_devices::latest_bdev, as it points to the device with the highest
fs_devices::generation number. This will contain the superblock updates
that other devices may have missed and we can now support reuniting
devices following failures of btrfstune -m|M|u|U as in the patches:

    btrfs-progs: add support to fix superblock with CHANGING_FSID_V2 flag
    btrfs-progs: recover from the failed btrfstune -m|M


> This lacks explanatni why it should use it, it's not obvious.

Could you please use the commit log above, or let me know
if a reroll is preferred?

Thanks, Anand