Hi all:

This is first reported to *libguestfs*: https://bugzilla.redhat.com/show_bug.cgi?id=624335

Then, I looked into upstream util-linux and it seems nothing wrong. I'm not convinced that it's a kernel bug.

produce:

---
# ./util-linux/disk-utils/blockdev --getbsz /dev/sda6
4096
# ./util-linux/disk-utils/blockdev --setbsz 2048 /dev/sda6
# ./util-linux/disk-utils/blockdev --getbsz /dev/sda6
4096
# ./util-linux/disk-utils/blockdev --setbsz 512 /dev/sda6
# ./util-linux/disk-utils/blockdev --getbsz /dev/sda6
4096

---

I'm not sure if it is related to write-back, but still CCed to Fengguang.



Thanks,
-Wanlong Gao