Re: [PATCH 1/4] Optimize NFS open() calls by means of 'intents'...

[Linus Torvalds]

On Fri, 23 May 2003, Trond Myklebust wrote:
> 
> Minor cleanup of open() code. Put the original open flags, mode, etc. into
> an 'opendata' structure that can be passed as an intent to lookup.

I don't mind the concepts, but I _really_ dislike the implementation.

For one thing, if you're creating a structure to pass in the flags for 
open, then you should take the time to make the code _more_ readable 
rather than less. In particular, the notion of having a structure like 
this:

	struct opendata {
		int flag;
		int mode;
		int acc_mode;
	};

where each of "flag" and "acc_mode" are magic bitfields just fills me with
horror. 

So why not make those internal modes that we translate the "flags" into be 
a real bitmap? That should make the code a lot more readable.

Also, I don't really understand why you want to have "opendata" and 
"intent" as different structures. That's _especially_ true now that the 
only intent is the "open" intent, but even if there were other intents, 
I'd rather have something like this

	struct lookup_info {
		enum type; /* open, validate, whatever.. */
		union {
			struct open_intent open;
			..
		} data;
	}

and gace tge flags (create/exclusive etc) inside that lookup_intent 
instead of having multiple different pointers and transferring data from 
one to the other at different phases of the "open".

Also, in patch 3/4, you do

	xxx_create(struct inode *dir, struct dentry *dentry, int mode, struct vfsintent *intent)

and that "mode" this I again find offensive: why is it not in the intent?  
It automatically _would_ be, if you only had one structure and one
pointer, but you lost it when you did the "opendata->intent"  
transformation.

So please don't have this artifical (and clearly broken) differentiation
between "intent" and "opendata". They should be one and the same thing:  
"lookup_info". Because that is what they _are_. They are not intents. They
are literally extra information for the lookup.

		Linus