Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-la0-f45.google.com ([209.85.215.45]:39078 "EHLO mail-la0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750732Ab3KEDAZ (ORCPT ); Mon, 4 Nov 2013 22:00:25 -0500 MIME-Version: 1.0 In-Reply-To: <1383614186-8039-1-git-send-email-jlayton@redhat.com> References: <1383614186-8039-1-git-send-email-jlayton@redhat.com> Date: Mon, 4 Nov 2013 21:00:23 -0600 Message-ID: Subject: Re: [PATCH] [RFC] vfs: don't revalidate dentries that serve as mountpoints From: Shirish Pargaonkar To: Jeff Layton Cc: viro@zeniv.linux.org.uk, linux-fsdevel , linux-nfs@vger.kernel.org, LKML , chutzpah@gentoo.org, liguangc@cn.ibm.com Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-nfs-owner@vger.kernel.org List-ID: For a similar issue in cifs vfs (samba bugzilla 8950), I was going to try unset the bit DCACHE_OP_REVALIDATE of d_flags of the dentry. Would something like work for the mountpoint dentry? On Mon, Nov 4, 2013 at 7:16 PM, Jeff Layton wrote: > We had a couple of reports of people that are mounting NFS filesystems, > and then bind mounting certain local files onto dentries in that nfs > mount (sort of like a poor-man's unionmount). > > This all works well until the dentry serving as the mountpoint fails > d_revalidate. The dentry will end up being invalidated which makes the > bind mount unreachable via pathwalk. > > It doesn't make much sense to me to allow dentries to serve as > mountpoints to end up invalidated, so there's no real point in > attempting to d_revalidate them at all. > > Reported-by: Patrick McLean > Reported-by: Guang Cheng Li > Signed-off-by: Jeff Layton > --- > fs/namei.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/fs/namei.c b/fs/namei.c > index caa2805..5b10ad0 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -585,6 +585,9 @@ drop_root_mnt: > > static inline int d_revalidate(struct dentry *dentry, unsigned int flags) > { > + /* dentries that serve as mountpoints are always considered valid */ > + if (d_mountpoint(dentry)) > + return 1; > return dentry->d_op->d_revalidate(dentry, flags); > } > > -- > 1.8.3.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html