No short term plans, as BTRFS is too new and unproven to be trusted backups.
Funny you should ask though, because we did research ZFS last month specifically for this purpose. ZFS because it has been extremely popular with the users of Linux-based repositories, especially service providers. However, it appeared that ZFS does not yet provide capabilities similar to BlockClone API of ReFS.
Here's some additional information from the internal forum discussion on the same subject:
Here's an LWN article from 2014 that talks a little about the BTRFS_IOC_CLONE and BTRFS_IOC_CLONE_RANGE which were ioctl functions specific to BTRFS, pretty simple stuff really:https://lwn.net/Articles/581558/
As of kernel 4.5 these functions were brought into the generic VFS level as FICLONE and FICLONERANGE ioctls:http://man7.org/linux/man-pages/man2/io ... nge.2.html
However, BTRFS remained the only filesystem with support at that time (although NFS v4 CLONE functions were implemented in nfsd to allow support via network), although the XFS developers were working on implementation, which is what made it make sense to bring the calls to the generic VFS layer. Just a little over a month ago you can see the commit to the 4.9-rc kernel tree for XFS to implement these ioctls:https://git.kernel.org/cgit/linux/kerne ... d16565c1bd
So perhaps once these have time to settle in, and a few major distros move to these newer kernels, it might be something that could be considered, but at this point I' think it is probably too early for sure.