btrfs-progs: check: write corrected qgroup info to disk

btrfs-progs: check: write corrected qgroup info to disk

Now that we can verify all qgroups, we can write the corrected qgroups out
to disk when '--repair' is specified. The qgroup status item is also updated
to clear any out-of-date state. The repair_ functions were modeled after the
inode repair code in cmds-check.c.

I also renamed the 'scan' member of qgroup_status_item to 'rescan' in order
to keep consistency with the kernel.

Testing this was easy, I just reproduced qgroup inconsistencies via the
usual routes and had btrfsck fix them.

Signed-off-by: Mark Fasheh <mfasheh@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>