From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Howells Subject: d_revalidate not being called enough on mountpoints? Date: Mon, 16 Apr 2007 13:50:24 +0100 Message-ID: <8505.1176727824@redhat.com> Cc: nfsv4@linux-nfs.org, linux-fsdevel@vger.kernel.org, dhowells@redhat.com To: viro@zeniv.linux.org.uk, trond.myklebust@fys.uio.no Return-path: Received: from mx1.redhat.com ([66.187.233.31]:42057 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030522AbXDPMuq (ORCPT ); Mon, 16 Apr 2007 08:50:46 -0400 Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Hi Al, I think there might be a problem in the VFS with d_revalidate() not being called enough on mountpoints. As far as I can tell from the printks in my AFS stuff, it's only called on the mounted-on dentry, and not the vfsmount-root dentry. However, with NFS at least (not so much AFS), can you trust that the mount-root dentry still maps to the same inode and event if it does that that inode is still up to date? I discovered it because I was relying on d_revalidate() to spot that the server had broken the callback on a directory that had been changed. However, the root directory of each volume isn't being d_revalidated. In the kernel output, I see: (1) Permission check on the root dir of /afs: volume ID 20000001, vnode ID 1: [0ls ] ==> afs_permission({20000001:1},1,) (2) Revalidation of the mountpoint dir in /afs (vnode ID 6): [0ls ] ==> afs_d_revalidate({v={20000001:6} n=.cambridge.redhat.com fl=20},) [0ls ] not promised (3) At this point, the stats of the mounted-on dir are rechecked. [0ls ] new promise [fl=20] (4) Permission check on the root dir of /afs/.cambridge.redhat.com (volume ID 20000003, vnode ID 1): [0ls ] ==> afs_permission({20000003:1},1,) (5) Revalidation of the mountpoint dir in /afs/.cambridge.redhat.com (vnode ID 2): [0ls ] ==> afs_d_revalidate({v={20000003:2} n=afsdoc fl=20},) [0ls ] not promised (6) Again, the stats of the mounted-on dir are rechecked. [0ls ] new promise [fl=20] I was expecting to see the root dentry of each vfsmount be revalidated, but that doesn't occur. David