===== Parsing mount points =====

When dealing with disk spindown, it can be important to parse the list of mount points, in order to alter mount options such as commit=, etc.
For this, it is important to take into accounts the differences between /etc/mtab and /proc/mounts, when the former is not a symlink to the latter.

Here's an example /etc/mtab rootfs entry:

  rootfs / rootfs rw,noatime,relatime,errors=continue,barrier=0,commit=7200 0 0

And here's its counterpart in /proc/mounts:

  /dev/root / ext3 rw,noatime,errors=continue,commit=7200,barrier=0,data=ordered 0 0

In one case, the device is "rootfs", in the other, it's "/dev/root"

So we can have a "real" device, or a "fake" device. To apply a remount command, we'll want the real one, so /proc/mounts shall be preferred.