Re: [PATCH v1 9/8] copy_file_range.2: New page documenting copy_file_range()

On Tue, Sep 08, 2015 at 01:39:18PM -0700, Darrick J. Wong wrote:

quoted

quoted

quoted

+The file descriptors must not refer to the same file.

Why?  btrfs (and XFS) reflink can handle the case of a file sharing blocks
with itself.

I've never really thought about it... Zach had that in his initial
submission, so mentioned it in the man page.  Should I remove that bit?

Yes, please!

I could be wrong, but I think btrfs only started supporting files that share
blocks with themselves relatively recently(?)

The support was added into the cloning ioctl itself, otherwise same-file
clones were always possible with a sidestep using another file.