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From: "J. Bruce Fields" <bfields@fieldses.org>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Christian Brauner <christian.brauner@ubuntu.com>,
	Jan Kara <jack@suse.cz>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Linux API <linux-api@vger.kernel.org>,
	Miklos Szeredi <miklos@szeredi.hu>
Subject: Re: open_by_handle_at() in userns
Date: Thu, 8 Apr 2021 12:08:44 -0400	[thread overview]
Message-ID: <20210408160844.GD25439@fieldses.org> (raw)
In-Reply-To: <CAOQ4uxjkr_3d3KUkjMCtdpg===ZOPOwv41bUBkTppLmqRErHZQ@mail.gmail.com>

On Thu, Apr 08, 2021 at 06:54:52PM +0300, Amir Goldstein wrote:
> They are understood to me :) but I didn't want to get into it, because it is
> complicated to explain and I wasn't sure if anyone cared...
> 
> I started working on open_by_handle_at() in userns for fanotify and fanotify
> mostly reports directory fhandle, so no issues with cross-directory renames.
> In any case, fanotify never reports "connectable" non-dir file handles.
> 
> Because my proposed change ALSO makes it possible to start talking about
> userspace nfs server inside userns (in case anyone cares), I wanted to lay
> out the path towards a userspace "subtree_check" like solution.

We have to support subdirectory exports and subtree checking because we
already have, but, FWIW, if I were writing a new NFS server from
scratch, I don't think I would.  It's poorly understood, and the effort
would be better spent on more flexible storage management.

--b.

> Another thing I am contemplating is, if and when idmapped mount support
> is added to overlayfs, we can store an additional "connectable" file handle
> in the overlayfs index (whose key is the non-connectable fhandle) and
> fix ovl_acceptable() similar to nfsd_acceptable() and then we will be able
> to mount an overlayfs inside userns with nfs_export support.
> 
> I've included a two liner patch on the fhandle_userns branch to allow
> overlayfs inside userns with nfs_export support in the case that
> underlying filesystem was mounted inside userns, but that is not such
> an interesting use case IMO.
> 
> Thanks,
> Amir.

  reply	other threads:[~2021-04-08 16:08 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-28 15:56 [RFC][PATCH] fanotify: allow setting FAN_CREATE in mount mark mask Amir Goldstein
2021-03-30  7:31 ` Christian Brauner
2021-03-30  9:31   ` Amir Goldstein
2021-03-30 16:24     ` Amir Goldstein
2021-03-31 10:08       ` Christian Brauner
2021-03-31 10:57         ` Amir Goldstein
2021-04-08 11:44         ` open_by_handle_at() in userns Amir Goldstein
2021-04-08 12:55           ` Christian Brauner
2021-04-08 14:15             ` J. Bruce Fields
2021-04-08 15:54               ` Amir Goldstein
2021-04-08 16:08                 ` J. Bruce Fields [this message]
2021-04-08 16:48                   ` Frank Filz
2021-04-08 15:34             ` Amir Goldstein
2021-04-08 15:41               ` Christian Brauner
2021-03-30 12:12 ` [RFC][PATCH] fanotify: allow setting FAN_CREATE in mount mark mask Christian Brauner
2021-03-30 12:33   ` Amir Goldstein
2021-03-30 12:53     ` Christian Brauner
2021-03-30 12:55       ` Christian Brauner
2021-03-30 13:54       ` Amir Goldstein
2021-03-30 14:17         ` Christian Brauner
2021-03-30 14:56           ` Amir Goldstein
2021-03-31  9:46             ` Christian Brauner
2021-03-31 11:29               ` Amir Goldstein
2021-03-31 12:17                 ` Christian Brauner
2021-03-31 12:59                   ` Amir Goldstein
2021-03-31 12:54                 ` Jan Kara
2021-03-31 14:06                   ` Amir Goldstein
2021-03-31 20:59                     ` fsnotify path hooks Amir Goldstein
2021-04-01 10:29                       ` Jan Kara
2021-04-01 14:18                         ` Amir Goldstein
2021-04-02  8:20                           ` Amir Goldstein
2021-04-04 10:27                             ` LSM and setxattr helpers Amir Goldstein
2021-04-05 12:23                               ` Christian Brauner
2021-04-05 14:47                               ` Mimi Zohar
2021-04-06 15:43                                 ` Amir Goldstein
2021-04-05 16:18                               ` Casey Schaufler
2021-04-06  8:35                           ` fsnotify path hooks Jan Kara
2021-04-06 18:49                           ` Amir Goldstein
2021-04-08 12:52                             ` Jan Kara
2021-04-08 15:11                               ` Amir Goldstein
2021-04-09 10:08                                 ` Jan Kara
2021-04-09 10:45                                   ` Christian Brauner
2021-04-20  6:01                                     ` Amir Goldstein
2021-04-20 11:41                                       ` Christian Brauner
2021-04-20 11:58                                         ` Amir Goldstein
2021-04-20 13:38                                         ` Christian Brauner
2021-04-09 13:22                                   ` Amir Goldstein
2021-04-09 14:30                                     ` Al Viro
2021-04-09 14:39                                       ` Christian Brauner
2021-04-09 14:46                                         ` Al Viro
2021-04-09 15:20                                           ` Christian Brauner
2021-04-09 16:06                                       ` Amir Goldstein
2021-04-09 16:09                                         ` Amir Goldstein
2021-04-18 18:51                                   ` Amir Goldstein
2021-04-19  8:08                                     ` Amir Goldstein
2021-04-19 16:41                                 ` Amir Goldstein
2021-04-19 17:02                                   ` Al Viro
2021-04-19 22:04                                     ` Amir Goldstein
2021-04-20  7:53                                       ` Amir Goldstein
2021-03-31 13:06                 ` [RFC][PATCH] fanotify: allow setting FAN_CREATE in mount mark mask J. Bruce Fields
2021-03-30 12:20 ` Amir Goldstein

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