[dm-devel] Partition size set to 0 when resizing extended and adding logical partition with BLKPG

[Phillip Susi]

On 4/9/2019 12:41 PM, Kai Lüke wrote:
> $ sudo ./sim loop0
> new size in /sys/block/loop0/loop0p1/size: 0
> issuing BLKRRPART
> new size in /sys/block/loop0/loop0p1/size: 2

> int resizepart(char *path, int start, int fd) {
>   struct blkpg_partition part;
>   struct blkpg_ioctl_arg ioctl_arg;
>   memset(&part, 0, sizeof(part));
>   part.start = start;
>   part.length = 1;

I would suggest changing length to 2.  This is what parted and partx do
and it seems to work there.  Linux has always exposed 2 sectors through
the extended partition so you can have lilo install itself there.  It
may be that the kernel thinks that is the minimum allowed size.