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Date:   Sat, 29 Aug 2020 17:13:58 +0100
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Dave Chinner <david@fromorbit.com>,
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Subject: Re: xattr names for unprivileged stacking?
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On Sat, Aug 29, 2020 at 05:07:17PM +0100, Matthew Wilcox wrote:

> I agree with you that supporting named streams within a file requires
> an independent inode for each stream.  I disagree with you that this is
> dentry cache infrastructure.  I do not believe in giving each stream
> its own dentry.  Either they share the default stream's dentry, or they
> have no dentry (mild preference for no dentry).

*blink*

Just how would they have different inodes while sharing a dentry?

> > The fact that ADS inodes would not be in the dentry cache and hence
> > not visible to pathwalks at all then means that all of the issues
> > such as mounting over them, chroot, etc don't exist in the first
> > place...
> 
> Wait, you've now switched from "this is dentry cache infrastructure"
> to "it should not be in the dentry cache".  So I don't understand what
> you're arguing for.

Bloody wonderful, that.  So now we have struct file instances with no dentry
associated with them?  Which would have to be taken into account all over
the place...