Re: [PATCH 3/4] FUSE: implement fuse_req->prep()

[Andrew Morton <akpm@linux-foundation.org>]

On Thu, 18 Jun 2009 18:24:32 +0900
Tejun Heo <tj@kernel.org> wrote:

> Implement ->prep() which is the opposite equivalent of ->end().

The opposite of "end" is "begin".  I'd expect to see a sequence like

	-> prep
	-> begin
	-> end

so the naming choice here is unexpected.

>  It's
> called right before the request is passed to userland server in the
> kernel context of the server.  ->prep() can fail the request without
> disrupting the whole channel.
> 
> This will be used by direct mmap implementation.

> ...
>
> --- a/fs/fuse/fuse_i.h
> +++ b/fs/fuse/fuse_i.h
> @@ -292,6 +292,12 @@ struct fuse_req {
>  	/** Link on fi->writepages */
>  	struct list_head writepages_entry;
>  
> +	/** Request preparation callback.  Called from the kernel
> +	    context of the FUSE server before passing the request to
> +	    the FUSE server.  Non-zero return from this function will
> +	    fail the request. */
> +	int (*prep)(struct fuse_conn *, struct fuse_req *);
> +
>  	/** Request completion callback.  This function is called from
>  	    the kernel context of the FUSE server if the request isn't
>  	    being aborted.  If the request is being aborted, it's

Why the strange comment layout?  Does kerneldoc actually recognise and
appropriately process this text?  if not, please do

	/*
	 * Request preparation callback.  Called from the kernel
	 * context of the FUSE server before passing the request to
	 * the FUSE server.  Non-zero return from this function will
	 * fail the request.
	 */

If that looks odd then, well, that wasn't your fault ;)