sbi->s_freeinodes_counter is only decreased by the ext2 code, it is never
increased. This patch fixes it.

Note that sbi->s_freeinodes_counter is only used in the algorithm that
tries to find the group for new allocations, so this bug is not easily
visible (the only visibility is that the group finding algorithm selects
inoptinal result).

Link: https://lore.kernel.org/r/alpine.LRH.2.02.2004201538300.19436@file01.intranet.prod.int.rdu2.redhat.comSigned-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>