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From: Miklos Szeredi <miklos@szeredi.hu>
To: Matthew Wilcox <willy@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
	Dave Chinner <david@fromorbit.com>,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	Greg Kurz <groug@kaod.org>,
	linux-fsdevel@vger.kernel.org,
	Stefan Hajnoczi <stefanha@redhat.com>,
	Miklos Szeredi <mszeredi@redhat.com>,
	Vivek Goyal <vgoyal@redhat.com>,
	Giuseppe Scrivano <gscrivan@redhat.com>,
	Daniel J Walsh <dwalsh@redhat.com>,
	Chirantan Ekbote <chirantan@chromium.org>
Subject: Re: xattr names for unprivileged stacking?
Date: Mon, 31 Aug 2020 16:21:36 +0200	[thread overview]
Message-ID: <CAJfpegvRgvU-RYf0i6ChC_v7aHonimLKe-5MuUa+JXqUHiPEpg@mail.gmail.com> (raw)
In-Reply-To: <20200831132339.GD14765@casper.infradead.org>

On Mon, Aug 31, 2020 at 3:23 PM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Mon, Aug 31, 2020 at 01:51:20PM +0200, Miklos Szeredi wrote:
> > On Mon, Aug 31, 2020 at 1:37 PM Matthew Wilcox <willy@infradead.org> wrote:
> >
> > > As I said to Dave, you and I have a strong difference of opinion here.
> > > I think that what you are proposing is madness.  You're making it too
> > > flexible which comes with too much opportunity for abuse.
> >
> > Such as?
>
> One proposal I saw earlier in this thread was to do something like
> $ runalt /path/to/file ls
> which would open_alt() /path/to/file, fchdir to it and run ls inside it.
> That's just crazy.

Indeed, I have said numerous times that fchdir() on those objects must
not happen.  But there's no law (that I know of) that says all
hierarchies of files must allow fchdir().

> > >  I just want
> > > to see alternate data streams for the same filename in order to support
> > > existing use cases.  You seem to be able to want to create an entire
> > > new world inside a file, and that's just too confusing.
> >
> > To whom?  I'm sure users of ancient systems with a flat directory
> > found directory trees very confusing.  Yet it turned out that the
> > hierarchical system beat the heck out of the flat one.
>
> Which doesn't mean that multiple semi-hidden hierarchies are going to
> be better than one visible hierarchy.

Look how metadata interfaces for inodes are already fragmented:

 - stat (zillions of versions due to field sizes)
 - statx (hopefully good for some time)
 - getxattr
 - FS_IOC_GETFLAGS
 - FS_IOC_FSGETXATTR (nothing to do with the "other" xattr)
 - FS_IOC_FIEMAP
 - all the filesystem specific stuff (encryption, compression, whatever)

And now you are proposing to add yet another interface specific to ADS.

What about a generic interface instead for most future use cases as
well as possibly duplicating some of the existing ones?  This would
simplify userspace tooling and allow for a single generic internal
interface as well.

Thanks,
Miklos

  reply	other threads:[~2020-08-31 14:22 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-28 10:55 Dr. David Alan Gilbert
2020-07-28 13:08 ` Greg Kurz
2020-07-28 13:55   ` Christian Schoenebeck
2020-08-04 11:28     ` Dr. David Alan Gilbert
2020-08-04 13:51       ` Christian Schoenebeck
2020-08-12 11:18         ` Dr. David Alan Gilbert
2020-08-12 13:34           ` Christian Schoenebeck
2020-08-12 14:33             ` Dr. David Alan Gilbert
2020-08-13  9:01               ` Christian Schoenebeck
2020-08-16 22:56                 ` Dave Chinner
2020-08-16 23:09                   ` Matthew Wilcox
2020-08-17  0:29                     ` Dave Chinner
2020-08-17 10:37                       ` file forks vs. xattr (was: xattr names for unprivileged stacking?) Christian Schoenebeck
2020-08-23 23:40                         ` Dave Chinner
2020-08-24 15:30                           ` Christian Schoenebeck
2020-08-24 20:01                             ` Miklos Szeredi
2020-08-24 21:26                             ` Frank van der Linden
2020-08-24 22:29                             ` Theodore Y. Ts'o
2020-08-25 15:12                               ` Christian Schoenebeck
2020-08-25 15:32                                 ` Miklos Szeredi
2020-08-27 12:02                                   ` Christian Schoenebeck
2020-08-27 12:25                                     ` Matthew Wilcox
2020-08-27 13:48                                       ` Christian Schoenebeck
2020-08-27 14:01                                         ` Matthew Wilcox
2020-08-27 14:23                                           ` Christian Schoenebeck
2020-08-27 14:25                                             ` Matthew Wilcox
2020-08-27 14:44                                             ` Al Viro
2020-08-27 16:29                                               ` Dr. David Alan Gilbert
2020-08-27 16:35                                                 ` Matthew Wilcox
2020-08-28  9:11                                                 ` Christian Schoenebeck
2020-08-28 14:46                                                   ` Theodore Y. Ts'o
2020-08-27 15:22                       ` xattr names for unprivileged stacking? Matthew Wilcox
2020-08-27 22:24                         ` Dave Chinner
2020-08-29 16:07                           ` Matthew Wilcox
2020-08-29 16:13                             ` Al Viro
2020-08-29 17:51                               ` Miklos Szeredi
2020-08-29 18:04                                 ` Al Viro
2020-08-29 18:22                                   ` Christian Schoenebeck
2020-08-29 19:13                                   ` Miklos Szeredi
2020-08-29 19:25                                     ` Al Viro
2020-08-30 19:05                                       ` Miklos Szeredi
2020-08-30 19:10                                         ` Matthew Wilcox
2020-08-31  7:34                                           ` Miklos Szeredi
2020-08-31 11:37                                             ` Matthew Wilcox
2020-08-31 11:51                                               ` Miklos Szeredi
2020-08-31 13:23                                                 ` Matthew Wilcox
2020-08-31 14:21                                                   ` Miklos Szeredi [this message]
2020-08-31 14:25                                                   ` Theodore Y. Ts'o
2020-08-31 14:45                                                     ` Matthew Wilcox
2020-08-31 14:49                                                       ` Miklos Szeredi
2020-09-01  3:34                                                     ` Dave Chinner
2020-09-01 14:52                                                       ` Theodore Y. Ts'o
2020-09-01 15:14                                                         ` Theodore Y. Ts'o
2020-09-02  5:19                                                           ` Dave Chinner
2020-08-31 18:02                                                   ` Andreas Dilger
2020-09-01  3:48                                                     ` Dave Chinner
2020-08-29 19:17                               ` Matthew Wilcox
2020-08-29 19:40                                 ` Al Viro
2020-08-29 20:12                                   ` Matthew Wilcox
2020-08-31 14:23                                     ` Theodore Y. Ts'o
2020-08-31 14:40                                       ` Matthew Wilcox
2020-08-31 16:11                                       ` Christian Schoenebeck

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