This name doesn't really fit with how the space reservation stuff works
now, rename it to btrfs_space_info_free_bytes_may_use so it's clear what
the function is doing.
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>