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From: Matthew Wilcox <willy@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Christian Schoenebeck <qemu_oss@crudebyte.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Greg Kurz <groug@kaod.org>,
linux-fsdevel@vger.kernel.org, stefanha@redhat.com,
mszeredi@redhat.com, vgoyal@redhat.com, gscrivan@redhat.com,
dwalsh@redhat.com, chirantan@chromium.org
Subject: Re: xattr names for unprivileged stacking?
Date: Mon, 17 Aug 2020 00:09:08 +0100 [thread overview]
Message-ID: <20200816230908.GI17456@casper.infradead.org> (raw)
In-Reply-To: <20200816225620.GA28218@dread.disaster.area>
On Mon, Aug 17, 2020 at 08:56:20AM +1000, Dave Chinner wrote:
> Indeed, most filesystems will not be able to implement ADS as
> xattrs. xattrs are implemented as atomicly journalled metadata on
> most filesytems, they cannot be used like a seekable file by
> userspace at all. If you want ADS to masquerade as an xattr, then
> you have to graft the entire file IO path onto filesytsem xattrs,
> and that just ain't gonna work without a -lot- of development in
> every filesystem that wants to support ADS.
>
> We've already got a perfectly good presentation layer for user data
> files that are accessed by file descriptors (i.e. directories
> containing files), so that should be the presentation layer you seek
> to extend.
>
> IOWs, trying to use abuse xattrs for ADS support is a non-starter.
One thing Dave didn't mention is that a directory can have xattrs,
forks and files (and acls). So your presentation layer needs to not
confuse one thing for another.
I don't understand why a fork would be permitted to have its own
permissions. That makes no sense. Silly Solaris.
next prev parent reply other threads:[~2020-08-16 23:09 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 [this message]
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
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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