From: Al Viro <viro@ZenIV.linux.org.uk>
To: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
Devel FS Linux <linux-fsdevel@vger.kernel.org>,
Torvalds Linus <torvalds@linux-foundation.org>,
Eric Biederman <ebiederm@xmission.com>
Subject: Re: [PATCH 00/11] [RFC] repair net namespace damage to rpc_pipefs
Date: Mon, 2 Dec 2013 15:57:22 +0000 [thread overview]
Message-ID: <20131202155722.GE10323@ZenIV.linux.org.uk> (raw)
In-Reply-To: <3C65EB4C-6592-44F8-B08D-E5A9EFD6C8C6@primarydata.com>
On Mon, Dec 02, 2013 at 08:44:25AM -0500, Trond Myklebust wrote:
> > I'll have to let the net namespace folks chime in for that, as far as
> > I'm concerned it's a featured better config'ed off. If they can't come
> > up with anything better the procfs hack above would be it.
>
> The lifetime of the kernel mount only needs to match that of the rpc_client, since each rpc_client is associated to a single net namespace, and each net namespace is in a 1-1 relationship with an rpc_pipefs super block.
>
> IOW: move the kernel mount/umount back to the rpc_client create/destroy methods and all should be well.
Hmm... I'm looking through rpc_pipe.c and there are some fun issues in there:
* ->kill_sb() *is* called after rpc_fill_super() failures. It's
not ->put_super() (and even ->put_super() would've been called for failures
past setting ->s_root). With ->s_fs_info set only on success, it means
that rpc_kill_sb() will just oops after such failure exits.
* just what is
if (sn->pipefs_sb != sb) {
mutex_unlock(&sn->pipefs_sb_lock);
goto out;
}
sn->pipefs_sb = NULL;
about? In which scenario is it not equal to ->pipefs_sb? When said
->pipefs_sb is NULL? But that, AFAICS, can happen only on cleanup after
failing rpc_fill_super(), in which case we won't get that sn thing in
the first place (in fact, we'll oops trying to get it).
Trond, am I right interpreting you as "that filesystem has non-empty
contents only when there is at least one rpc_client in that netns;
after rpc_client removal there won't be any accesses to data structures
associated with it (due to rpc_close_pipes() and friends, presumably),
so there won't be any need to keep netns alive after that"?
If so and if rpc_client really can't outlive netns, then yes, having each
of them hold an internal vfsmount reference pinning rpc_pipefs down would
suffice.
next prev parent reply other threads:[~2013-12-02 15:57 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-01 13:14 [PATCH 00/11] [RFC] repair net namespace damage to rpc_pipefs Christoph Hellwig
2013-12-01 13:14 ` [PATCH 01/11] sunrpc: allocate pipefs inodes using kmalloc Christoph Hellwig
2013-12-01 14:26 ` Jeff Layton
2013-12-01 13:14 ` [PATCH 02/11] rpc_pipefs: always mount on net namespace initialization Christoph Hellwig
2013-12-01 15:24 ` Jeff Layton
2013-12-01 13:14 ` [PATCH 03/11] sunrpc: remove the rpc_clients_block notifier Christoph Hellwig
2013-12-01 15:25 ` Jeff Layton
2013-12-01 13:14 ` [PATCH 04/11] sunrpc: no need to have a lock or superblock for rpc_unlink Christoph Hellwig
2013-12-01 13:14 ` [PATCH 05/11] sunprc: add sensible pipe creation and removal helpers Christoph Hellwig
2013-12-01 13:14 ` [PATCH 06/11] sunrpc: clean up rpc_pipefs client dir creation Christoph Hellwig
2013-12-01 13:14 ` [PATCH 07/11] sunrpc: make rpc_mkdir_populate net-namespace aware Christoph Hellwig
2013-12-01 13:14 ` [PATCH 08/11] sunrpc: rpc_get_sb_net, die, die, die Christoph Hellwig
2013-12-01 13:14 ` [PATCH 09/11] nfs: convert idmapper to rpc_mkpipe_clnt Christoph Hellwig
2013-12-01 13:14 ` [PATCH 10/11] auth_gss: convert " Christoph Hellwig
2013-12-01 13:14 ` [PATCH 11/11] sunrpc: rpc_pipefs cleanup Christoph Hellwig
2013-12-01 14:36 ` [PATCH 00/11] [RFC] repair net namespace damage to rpc_pipefs Jeff Layton
2013-12-01 15:44 ` Jeff Layton
2013-12-01 15:57 ` Jeff Layton
2013-12-01 18:13 ` Al Viro
2013-12-02 8:12 ` Christoph Hellwig
2013-12-02 13:44 ` Trond Myklebust
2013-12-02 14:24 ` Stanislav Kinsbursky
2013-12-02 15:36 ` Christoph Hellwig
2013-12-02 15:58 ` Trond Myklebust
2013-12-03 7:24 ` Stanislav Kinsbursky
2013-12-02 15:34 ` Christoph Hellwig
2013-12-02 16:00 ` Trond Myklebust
2013-12-02 16:27 ` Christoph Hellwig
2013-12-02 16:46 ` Trond Myklebust
2013-12-02 16:33 ` Jeff Layton
2013-12-02 16:37 ` J. Bruce Fields
2013-12-02 16:45 ` Jeff Layton
2013-12-02 15:57 ` Al Viro [this message]
2013-12-02 16:04 ` Trond Myklebust
2013-12-03 2:11 ` [RFC] alloc_pid() breakage Al Viro
2013-12-02 7:23 ` [PATCH 00/11] [RFC] repair net namespace damage to rpc_pipefs Stanislav Kinsbursky
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