[Ocfs2-devel] [PATCH 1/3] fs: Document the reflink(2) system call.

[Jamie Lokier]

Joel Becker wrote:
> On Tue, May 05, 2009 at 10:57:11PM +0100, Jamie Lokier wrote:
> > jim owens wrote:
> > > 3) the granularity of the COW (1-byte write may cause
> > >    1-block up through whole file copy) is fs-dependent.
> > 
> > And yet ENOSYS if the fs cannot implement any COW, and it isn't
> > possible for userspace to duplicate the semantics by explicit copying?
> 
> 	The point-in-time of the snapshot is what's important here.

Don't we have a slight problem that useful point-in-time snapshots
really need to snapshot whole directory trees?  Otherwise you get the
same inter-file inconsistency issues that you get intra-file from old
fashioned copying.

-- Jamie