[Dump-users] restore -C and mount points

[Kenneth P. <sh...@se...>]

I see lots of miscompares in my root filesystem dump that result from a 
mount point on the filesystem masking the matching underlying structures in 
the dump file. (Examples include /misc, /dev, /proc, /sys, /selinux, and of 
course /mnt/*.) Most of the miscompares are for attributes (both mode and 
selinux labels).

It would be desirable if these miscompares were instead reported with a 
different message to identify the true nature of the miscompare. For 
example, "<path> masked by mount point <mount point>".

My intuition is that these reports should not be counted towards the 
miscompare count, since mount points are intentional and not visible to 
dump.

(Alas, I don't know which API to use to query a path's filesystem. I use 
"df <path>" from the command line, so I'd go digging through the df source 
for that.)