Re: Named streams, Re: Cleaning up namei

[Dieter Baron <dillo%KD119105101110.ppp-bb.dion.ne.jp@localhost>]

In article <20080327221434.GA22378%netbsd.org@localhost> David wrote:
: On Sun, Mar 23, 2008 at 02:23:07PM -0700, Bill Stouder-Studenmund wrote:
:  > > > Mac OS used to have "complex" vnodes, which were files that had named 
:  > > > forks. They acted like files, but you could do lookups on them. Mac OS
:  > > > no longer has them, so I consider them a dead experiment. ;-)
:  > > 
:  > > But there's no reason they should be prohibited by the VFS layer.
:  > 
:  > I believe there is. It adds complexity, and I feel we win nothing for the 
:  > complexity. Look at all the issues you are having with the complexity we 
:  > actually use!

: That's quite true, except that the conclusion I drew upthread was that
: the vfs layer doesn't have to do anything special; it's up to the fs
: to decide to offer VOP_LOOKUP (and/or CREATE, LINK, RENAME, etc.) on
: regular files as well as directories. I don't think any particular
: complexity results; *forbidding* that somehow would add complexity.

:  > No one really needs to be able to handle named streams this way, so let's 
:  > not.

: Granted.

  Not quite: Mac OS X let's you access a file's resource fork as
<file>/rsrc.  NetBSD's HFS+ implementation currently supports this,
too, and I think it would be bad to loose this.

: Also, I tend to think multistreamed files are an abomination;

  Agreed, and so does Apple, now.  But there are tons of files with
resource forks out there, and users have a legitimate need to read
them.

: I'm not about to go rush out and implement them. There are dozens of
: perfectly good container formats one can use... native multistreamed
: files serve next to no purpose and make life difficult for users and
: sysadmins.

: I would, however, like to avoid coding in assumptions about what vnode
: types can support what operations; that way the behavior is only
: specified in one place instead of several. If we decide the latitude
: of fses to do weird things should be restricted, the best way to do
: that is some kind of compile-time check on VOP lists.

                                        yours,
                                        dillo