next-20210511 - btrfs build failure on arm

[Valdis Klētnieks]

An arm allmodconfig build died with:

ERROR: modpost: "__aeabi_uldivmod" [fs/btrfs/btrfs.ko] undefined!

Some digging around with nm and looking at the assembler points at:

@ /usr/src/linux-next/fs/btrfs/extent_io.c:2676:        const int nr_bits = (end + 1 - start) / fs_info->sectorsize_bits;
        adds    r1, r1, #1      @, tmp552, 
        adc     r0, r0, #0      @, tmp551, 
        ldr     r3, [r5, #1576] @ tmp2, _47->sectorsize_bits
        bl      __aeabi_uldivmod                @       

Introduced by this commit:

commit 6512659d8f13015dccfb38a13c6d117d22572019
Author: Qu Wenruo <wqu@xxxxxxxx>
Date:   Mon May 3 10:08:55 2021 +0800

    btrfs: submit read time repair only for each corrupted sector

Looks like that line could use something from include/linux/math.h