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

[Eric Deplagne]

On Thu, 29 Nov 2018 16:39:48 -0600, Eric Blake wrote:
> 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

  Maybe the closest thing to a bug there is that /mnt/bar/subfs does not have 
contents.

-- 
  Eric Deplagne

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