Re: b_dev vs. b_rdev confusion

> how do the inode->i_dev, i_rdev fit into this?

These are what you see with stat(2).
i_dev gives the device the file is on
i_rdev is usually undefined, but for device special files
it gives the real device.

> Is there a set rule on when/where one should use a buffer head's
> b_dev and when/where one should use b_rdev?

b_dev gives the device the user was thinking about
b_rdev is the actual underlying device

Andries