ext4: fix overhead calculation to account for the reserved gdt blocks

stable inclusion
from stable-v5.10.113
commit 4789149b9ea2a1893c62d816742f1a76514fc901
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5ISAH

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4789149b9ea2a1893c62d816742f1a76514fc901



--------------------------------

commit 10b01ee9 upstream.

The kernel calculation was underestimating the overhead by not taking
into account the reserved gdt blocks.  With this change, the overhead
calculated by the kernel matches the overhead calculation in mke2fs.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>