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

[Delian Krustev]

On Thursday, November 29, 2018 4:39:48 PM EET Eric Blake <address@hidden> 
wrote:
> 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,

NILFS allows time traveling - you can mount an old snapshot and can see two 
points in time of the same filesystem. Thus it is the same dev (there is no 
practice dev numbers to be time dependent).

This is also valid for files.
Files with the same dev/inode can have different contents.

> 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.

This can be easily cross-reported to LKML. If "diff" developers blame the 
kernel/fs both parties should discuss it as its unacceptable a core utility to 
be unusable. ( I'm pretty sure though, that the kernel developers will be 
convinced that it does not need change. )

All we need is command line option which can turn off the comparison by dev/
inode. Does not sound like too much work.

Or maybe you are worried about changing the API ?