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

[Jamie Lokier]

Jörn Engel wrote:
> On Tue, 5 May 2009 18:46:19 +0200, Jörn Engel wrote:
> > And depending on the fs design, the read/write loop can be
> > replaced with finer-grained reference counting.
> 
> And maybe finer-grained reference counting should be a requirement for
> copyfile/cowlink/reflink or whatever we call it.  With a large file on
> slow media, open("foo", O_RDWR); should still return in a reasonable
> amount of time.  Not after ten minutes.

Or 8 hours, which is how long it took me to copy a really large file
last time...

Oh, and are open() or write() on regular files interruptible per POSIX?
Didn't think so :-)

Fortunately BTRFS does do fine-grained extent sharing, and reflink
so it should work ok on BTRFS.

-- Jamie