Need advice about do we need this if condition

Steve French smfrench at
Wed Apr 17 09:32:12 EDT 2019

On Wed, Apr 17, 2019 at 2:59 AM Valdis Klētnieks
<valdis.kletnieks at> wrote:
> On Wed, 17 Apr 2019 08:25:22 +0300
> (Adding Al Viro and the linux-fsdevel lists, as at the very least, the manpage
> for the syscall needs some clarification...)
> > hello I am trying to fix
> So - convince us that it's in fact a "bug" and not a restriction.
> > I found cause
> > not
> > sure is it correct to remove such condition ?
> Does the CIFS protocol support copying from a file to another location in the
> same file? Was it intended to work on *any* filesystem?

Looks like it should be allowed on the same file as long as the source
and target file ranges do not overlap

section and 2.3.8
Server returns STATUS_NOT_SUPPORTED if "The source and target
destination ranges overlap on the same file."

and line 112 and following of smb2_ioctl_filesys.c in Samba code;a=blob;f=source3/smbd/smb2_ioctl_filesys.c;h=8a9c8c64ec9ddbca4623251555f4792d76aa6e44;hb=refs/heads/master#l112

> (For that matter, the manpage for the syscall is unclear on whether having both
> file descriptors open on the same file is OK or not - for bonus ambiguity
> points, there's exactly zero discussion of what happens if source and
> destination overlap destructively).



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