Re: [PATCH v5 8/9] vfs: Add vfs_copy_file_range() support for pagecache copies

On Mon, Oct 12, 2015 at 04:17:49PM -0700, Darrick J. Wong wrote:

Hm.  Peng's patches only generalize the CLONE and CLONE_RANGE ioctls from
btrfs, however they don't port over the (vastly different) EXTENT_SAME ioctl.

What does everyone think about generalizing EXTENT_SAME?  The interface enables
one to ask the kernel to dedupe multiple file ranges in a single call.  That's
more complex than what I was proposing with COPY_FR_DEDUP(E), but I'm assuming
that the extra complexity buys us the ability to ... multi-dedupe at the same
time, with locks held on the source file?

I'm happy to generalize the existing EXTENT_SAME, but please yell if you really
hate the interface.

It's not pretty, but if the btrfs folks have a good reason for it I
don't see a reason to diverge.