From: Djalal Harouni <tixxdz@gmail.com>
To: David Howells <dhowells@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
Linux FS Devel <linux-fsdevel@vger.kernel.org>,
linux-nfs@vger.kernel.org,
linux-kernel <linux-kernel@vger.kernel.org>,
Miklos Szeredi <mszeredi@redhat.com>
Subject: Re: [RFC][PATCH 0/9] VFS: Introduce mount context
Date: Mon, 8 May 2017 19:03:43 +0200 [thread overview]
Message-ID: <CAEiveUdYsVPuhEOjDJYtTN2JaPrEacE7ZeCUp3RhOkugK-ZtHg@mail.gmail.com> (raw)
In-Reply-To: <149382747487.30481.15428192741961545429.stgit@warthog.procyon.org.uk>
On Wed, May 3, 2017 at 6:04 PM, David Howells <dhowells@redhat.com> wrote:
>
> Here are a set of patches to create a mount context prior to setting up a
> new mount, populating it with the parsed options/binary data and then
> effecting the mount.
>
> This allows namespaces and other information to be conveyed through the
> mount procedure. It also allows extra error information to be returned
> (so many things can go wrong during a mount that a small integer isn't
> really sufficient to convey the issue).
>
> This also allows Miklós Szeredi's idea of doing:
>
> fd = fsopen("nfs");
> write(fd, "option=val", ...);
> fsmount(fd, "/mnt");
This may help to clear the boundary between what you can do with a
vfsmount (bind) and the filesystem. In containers, orchestration
tools, etc bind mounts are treated in a dynamic way, there is
assumption on github where developers and users expect that they can
dynamically add/move mounts between namespaces, however this won't
work with userns, so maybe this will help... My other suggestions:
Clear documentation and code comments will really help! I posted and
used some UID shifting within VFS layer patches a year ago, and it
seems that they really need something like this... !
I'm not sure where I did read about netlink, but at least it should
count userspace capabilities and namespace privacy/context...
> that he presented at LSF-2017 to be implemented (see the relevant patches
> in the series), to which I can add:
>
> read(fd, error_buffer, ...);
>
> to read back any error message. I didn't use netlink as that would make it
> depend on CONFIG_NET and would introduce network namespacing issues.
>
> I've implemented mount context handling for procfs and nfs.
>
> Further developments:
>
> (*) Implement mount context support in more filesystems, ext4 being next
> on my list.
>
> (*) Move the walk-from-root stuff that nfs has to generic code so that you
> can do something akin to:
>
> mount /dev/sda1:/foo/bar /mnt
>
> See nfs_follow_remote_path() and mount_subtree(). This is slightly
> tricky in NFS as we have to prevent referral loops.
>
> (*) Move the pid_ns pointer from struct mount_context to struct
> proc_mount_context as I'm not sure it's necessary for anything other
> than procfs.
FWIW the RFC "proc: support private proc instances per pidnamespace"
[1] that I have to clean will hide pid_ns under procfs filesystem, so
maybe that's a good reason to move it then get rid of it.
Thanks!
[1] https://lkml.org/lkml/2017/4/25/282
--
tixxdz
prev parent reply other threads:[~2017-05-08 17:03 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-03 16:04 [RFC][PATCH 0/9] VFS: Introduce mount context David Howells
2017-05-03 16:04 ` [PATCH 1/9] Provide a function to create a NUL-terminated string from unterminated data David Howells
2017-05-03 16:55 ` Jeff Layton
2017-05-03 19:26 ` Rasmus Villemoes
2017-05-03 20:13 ` David Howells
2017-05-03 16:04 ` [PATCH 2/9] Clean up whitespace in fs/namespace.c David Howells
2017-05-03 16:04 ` [PATCH 3/9] VFS: Introduce a mount context David Howells
2017-05-03 18:13 ` Jeff Layton
2017-05-03 18:26 ` Joe Perches
2017-05-03 20:38 ` Matthew Wilcox
2017-05-03 21:36 ` Joe Perches
2017-05-04 6:28 ` Julia Lawall
2017-05-03 21:17 ` David Howells
2017-05-03 18:37 ` David Howells
2017-05-03 18:43 ` Joe Perches
2017-05-03 20:11 ` David Howells
2017-05-04 9:27 ` David Howells
2017-05-04 14:34 ` Joe Perches
2017-05-03 21:43 ` Rasmus Villemoes
2017-05-04 10:22 ` David Howells
2017-05-08 15:05 ` Miklos Szeredi
2017-05-08 22:57 ` David Howells
2017-05-09 8:03 ` Miklos Szeredi
2017-05-10 12:41 ` Karel Zak
2017-05-09 9:32 ` David Howells
2017-05-09 11:04 ` Miklos Szeredi
2017-05-09 9:41 ` David Howells
2017-05-09 12:02 ` Miklos Szeredi
2017-05-09 18:51 ` Jeff Layton
2017-05-10 7:24 ` Miklos Szeredi
2017-05-10 8:05 ` David Howells
2017-05-10 13:20 ` Jeff Layton
2017-05-10 13:30 ` Miklos Szeredi
2017-05-10 13:33 ` Miklos Szeredi
2017-05-10 13:48 ` Jeff Layton
2017-05-12 8:15 ` Miklos Szeredi
2017-05-10 13:31 ` David Howells
2017-05-10 13:37 ` Jeff Layton
2017-05-09 9:56 ` David Howells
2017-05-09 12:38 ` Miklos Szeredi
2017-05-03 16:05 ` [PATCH 4/9] Implement fsopen() to prepare for a mount David Howells
2017-05-03 18:37 ` Jeff Layton
2017-05-03 18:41 ` David Howells
2017-05-03 20:44 ` Rasmus Villemoes
2017-05-04 10:40 ` Karel Zak
2017-05-04 12:55 ` David Howells
2017-05-04 12:58 ` David Howells
2017-05-04 13:06 ` David Howells
2017-05-04 13:34 ` Karel Zak
2017-05-09 18:40 ` Jeff Layton
2017-05-08 15:10 ` Miklos Szeredi
2017-05-08 23:09 ` David Howells
2017-05-03 16:05 ` [PATCH 5/9] Implement fsmount() to effect a pre-configured mount David Howells
2017-05-03 16:05 ` [PATCH 6/9] Sample program for driving fsopen/fsmount David Howells
2017-05-03 16:05 ` [PATCH 7/9] procfs: Move proc_fill_super() to fs/proc/root.c David Howells
2017-05-03 16:05 ` [PATCH 8/9] proc: Support the mount context in procfs David Howells
2017-05-03 16:05 ` [PATCH 9/9] NFS: Support the mount context and fsopen() David Howells
2017-05-03 16:44 ` [RFC][PATCH 0/9] VFS: Introduce mount context Jeff Layton
2017-05-03 16:50 ` David Howells
2017-05-03 17:27 ` Jeff Layton
2017-05-05 14:35 ` Miklos Szeredi
2017-05-05 15:47 ` David Howells
2017-05-08 8:25 ` Miklos Szeredi
2017-05-08 8:35 ` David Howells
2017-05-08 8:43 ` Miklos Szeredi
2017-05-08 17:03 ` Djalal Harouni [this message]
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