Commit 24542bf7ea changed preallocation of
extents to cap the max size we try to allocate. It's a valid change,
but the extent reservation code is also used by balance, and that
can't tolerate a smaller extent being allocated.
__btrfs_prealloc_file_range already has a min_size parameter, which is
used by relocation to request a specific extent size. This commit
adds an extra check to enforce that minimum extent size.
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Reported-by: Stefan Behrens <sbehrens@giantdisaster.de>
