Re: mv: move files across bind mounts using the rename syscall

[Rob Landley]

On 12/6/24 06:07, Milan Hauth wrote:
> currently mv fails to detect an identical filesystem
> of source and destination file across bind mounts
>
> instead of using the rename syscall
> mv copies the file (to the same filesystem)
> and then deletes the source file
>
> obviously, this is not ideal:
>
> - slow
> - waste of disk space
> - change of inode number
> - unnecessary disk write operations (destructive)
>
> > currently mv fails to detect an identical filesystem
> > of source and destination file across bind mounts
>
> this is possible using /proc/self/mountinfo
> proof of concept:
> https://github.com/milahu/move-files-across-bind-mounts

Is there a downside to always trying rename() first and doing the copy 
if it fails? That's approximately what toybox's mv does...

Rob