[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Unionmount. Basic details

From: Da Zheng
Subject: Re: Unionmount. Basic details
Date: Mon, 13 Apr 2009 23:44:47 +0100
User-agent: Thunderbird (Macintosh/20090302)


Carl Fredrik Hammar wrote:
It is not fully clear right now -- I realized that there is another
decision to make: should the unionmount translator be directly visible
as the translator attached to the mount node; or should it serve as a
proxy, forwarding all requests on the filesystem port to the target
translator -- thus making itself more or less transparent, so it appears
as if the target was attached to the mount node directly?

I tend towards the latter.

I think the latter makes a lot more sense.  I can't think of any reason
to let the mountee be aware that it's detached from the underlying
file system.  If anything it would just confuse it.
I think the first approach has its advantage. One very important reason is the performance. We are writing OS, after all. With the second approach, all requests from the application to the file system are twice expensive as before. But with the first approach it is possible that unionmount translator can expose the port to the node in the underlying file system to the outside world and later the application can access the underlying node with that port directly (unionmount isn't involved in the following operations such as reading and writing). I might be mistaken. I don't know much how unionfs works and whether unionmount can work in this way.

Zheng Da

reply via email to

[Prev in Thread] Current Thread [Next in Thread]