From: Trond Myklebust Subject: Re: [PATCH 2/5] VFS: Add VFS helper functions for setting up private namespaces Date: Tue, 23 Jun 2009 17:29:49 -0400 Message-ID: <1245792589.5133.24.camel@heimdal.trondhjem.org> References: <20090622190913.27923.31665.stgit@heimdal.trondhjem.org> <20090622190913.27923.61549.stgit@heimdal.trondhjem.org> <20090623201307.GA25760@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Linus Torvalds , Al Viro , Christoph Hellwig , linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org To: "Serge E. Hallyn" Return-path: Received: from mx2.netapp.com ([216.240.18.37]:18830 "EHLO mx2.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754022AbZFWVaL (ORCPT ); Tue, 23 Jun 2009 17:30:11 -0400 In-Reply-To: <20090623201307.GA25760@us.ibm.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Tue, 2009-06-23 at 15:13 -0500, Serge E. Hallyn wrote: > Quoting Trond Myklebust (Trond.Myklebust@netapp.com): > > The purpose of this patch is to improve the remote mount path lookup > > support for distributed filesystems such as the NFSv4 client. > > > > When given a mount command of the form "mount server:/foo/bar /mnt", the > > NFSv4 client is required to look up the filehandle for "server:/", and > > then look up each component of the remote mount path "foo/bar" in order > > to find the directory that is actually going to be mounted on /mnt. > > Following that remote mount path may involve following symlinks, > > crossing server-side mount points and even following referrals to > > filesystem volumes on other servers. > > > > Since the standard VFS path lookup code already supports walking paths > > that contain all these features (using in-kernel automounts for > > following referrals) we would like to be able to reuse that rather than > > duplicate the full path traversal functionality in the NFSv4 client code. > > > > This patch therefore defines a VFS helper function create_mnt_ns(), that > > sets up a temporary filesystem namespace and attaches a root filesystem to > > it. It exports the create_mnt_ns() and put_mnt_ns() function for use by > > filesystem modules. > > > > Signed-off-by: Trond Myklebust > > This looks good, thanks. Though I see no reason not to also switch over > init_mount_tree() to the new helper. > > (Seems plausible that c/r code would use this as well) > > Reviewed-by: Serge Hallyn > > thanks, > -serge Thanks for the review! I missed the code duplication in init_mount_tree(). Something like the following? Cheers Trond -------------------------------------------------------------------- From: Trond Myklebust VFS: Switch init_mount_tree() to use the new create_mnt_ns() helper Eliminates some duplicated code... Signed-off-by: Trond Myklebust --- fs/namespace.c | 11 ++--------- 1 files changed, 2 insertions(+), 9 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index a7bea8c..4a86b85 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2222,16 +2222,9 @@ static void __init init_mount_tree(void) mnt = do_kern_mount("rootfs", 0, "rootfs", NULL); if (IS_ERR(mnt)) panic("Can't create rootfs"); - ns = kmalloc(sizeof(*ns), GFP_KERNEL); - if (!ns) + ns = create_mnt_ns(mnt); + if (IS_ERR(ns)) panic("Can't allocate initial namespace"); - atomic_set(&ns->count, 1); - INIT_LIST_HEAD(&ns->list); - init_waitqueue_head(&ns->poll); - ns->event = 0; - list_add(&mnt->mnt_list, &ns->list); - ns->root = mnt; - mnt->mnt_ns = ns; init_task.nsproxy->mnt_ns = ns; get_mnt_ns(ns); -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@netapp.com www.netapp.com