[bug-diffutils] bug#33467: bug#33467: bug#33467: "diff" can not scan directories with same dev/inode

[Eric Blake]

On 11/29/18 4:32 PM, Mark Raymond wrote:
> This sounds similar to a problem I have just encountered.
>
> If I have filesystems mounted at:
>
>      /mnt/foo
>      /mnt/foo/subfs
>
> then do
>
>      mount --bind /mnt/foo /mnt/bar
>
> then the contents of `/mnt/foo` and `/mnt/bar` are different, because 
> `/mnt/foo/subfs` has contents but `/mnt/bar/subfs` does not have 
> contents. However
>
>      diff -r /mnt/foo /mnt/bar
>
> returns no results. However in my case, rsync is also unable to show the 
> differences.

POSIX says that a file is uniquely determined by its inode and device 
number. If you have a file system that reports the same device for 
different contents, your file system is broken, and it's no wonder that 
LOTS of Unix tools will fail to see the differences, because your file 
system is lying.  We can't fix it in diffutils; that would have to be a 
fix in the kernel implementation of your file system driver.

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org