Bug#648367: device-mapper devices such as dm-crypt always have rotational=1; should inherit "rotational" setting from underlying devices

[Josh Triplett <josh@joshtriplett.org>]

Source: linux-2.6
Version: 3.1.0-1~experimental.1
Severity: normal

I use dm-crypt on my system, and I have an SSD.  The underlying disk
device, sda, has rotational=0:

~$ cat /sys/block/sda/queue/rotational
0

However, the device-mapper devices have rotational=1:

~$ head /sys/block/dm-*/queue/rotational
==> /sys/block/dm-0/queue/rotational <==
1

==> /sys/block/dm-1/queue/rotational <==
1

==> /sys/block/dm-2/queue/rotational <==
1

The device-mapper devices should inherit the setting for "rotational"
from their underlying devices.

- Josh Triplett

-- System Information:
Debian Release: wheezy/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 3.1.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=C.UTF-8, LC_CTYPE=C.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash