copy-on-write files

[Joel Becker]

On Mon, May 11, 2009 at 12:08:17PM -0500, Steve French wrote:
> Joel,
> Looking at your documentation for the new "reflink" syscall (to create
> copy-on-write files):
> http://git.kernel.org/?p=linux/kernel/git/jlbec/ocfs2.git;a=blob;f=Documentation/filesystems/reflink.txt;h=58a6b3879114c0cb591fb736152b30291037edd2;hb=c04db1c934e67337318b177688c0b882297fdd66
> 
> Have you looked at whether this is close enough to the existing (e.g.
> Windows NTFS) copy-on-write syntax/feature so that we could use it
> under Samba (and on the client side from cifs and in the future smb2).
>   Windows added copy-on-write about 9 or 10 years ago and uses it
> extensively. although I have not researched enough to see what
> creating these would look like over the network.

	I didn't know NTFS had it, I don't know the syntax and behavior,
and I wonder where Windows uses it (I haven't encountered it on Windows
machines, but perhaps it is hidden).  Do you have a pointer to any
non-encumbered documentation about the feature?

Joel

-- 

"If the human brain were so simple we could understand it, we would
 be so simple that we could not."
	- W. A. Clouston

Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker at oracle.com
Phone: (650) 506-8127