Re: COW files

[Lexington Luthor <Lexington.Luthor@gmail.com>]

David Masover wrote:
> Gregory Maxwell wrote:
> 
>> Files could be COWed by a flag on the cp command (or really, perhaps
>> that should be the default behavior) or with a utility (perhaps run as
>> a periodic script to locate duplicates and COW them. This would
>> greatly speed up the process of copying files.
> 
> Should be on the cp command, but you have to change the cp source for
> that, and everything implementing "copy", including desktop managers.
> There's currently no "copy" system call.  So it's more than just a plugin.
> 

I would love something like this for entire directory trees. Perhaps 
with a reiser4 specific tool that does a COW cp -al.

At the moment, I have to cp -al and use a userspace solution 
(LD_PRELOADed library which traps the open call) to get working COW on 
reiser4.

I am not concerned too much with space usage, but speed is very 
important. This is usually not a problem with reiser4 because it so 
rarely hits the disk with COW trees.

- LL