xfs_repair: check free space requirements before allowing upgrades

xfs_repair: check free space requirements before allowing upgrades

Currently, the V5 feature upgrades permitted by xfs_repair do not affect
filesystem space usage, so we haven't needed to verify the geometry.

However, this will change once we start to allow the sysadmin to add new
metadata indexes to existing filesystems.  Add all the infrastructure we
need to ensure that there's enough space for metadata space reservations
and per-AG reservations the next time the filesystem will be mounted.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>
[david: Recompute transaction reservation values; Exit with error if upgrade fails]
Signed-off-by: Dave Chinner <david@fromorbit.com>
[djwong: Refuse to upgrade if any part of the fs has < 10% free]
Reviewed-by: Christoph Hellwig <hch@lst.de>