Re: [PATCH] fuse: Add support for fuse stacked I/O

From: Linus Torvalds
Date: Fri Jan 15 2016 - 16:43:44 EST

On Fri, Jan 15, 2016 at 11:29 AM, Nikhilesh Reddy <reddyn@xxxxxxxxxxxxxx> wrote:
> FUSE allows users to implement extensions to filesystems ..such as enforcing policy or permissions without having to modify the kernel or maintain the policy in the kernel.
> One such example is what was quoted by Antonio above ..
> Another example is a fuse based filesystem that tries to enforce additional permissions on a FAT based mount point.
> From what i could google there are many FUSE based filesystems out there that do things during the open call but simply pass through the read/and write I/O calls to the local "lower" filesystem where they actually store the data.

So I think these are valid use-cases, and I just think that they should

(a) be documented in the commit message as explanations of why people
would do this/

(b) not be called "stacked", because that tends to have some other
connotations to fs people.

I don't know what a better term would be, but you yourself used "pass
through". Maybe that (perhaps together with a clarification that it's
a per-file thing) might work fine.

Btw, why is mmap not passed through? That sounds fairly simple and
straightforward, I'm not seeing why it would be missing.