From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Pearson Subject: Re: "Permission denied" on autofs mount point Date: Wed, 20 Mar 2002 14:56:02 +0000 Sender: nfs-admin@lists.sourceforge.net Message-ID: <3C98A302.7E99AB4@moving-picture.com> References: <3C9098C4.56E187EF@moving-picture.com> <3C91F881.CD5594A7@moving-picture.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Received: from mpc-26.sohonet.co.uk ([193.203.82.251] helo=moving-picture.com) by usw-sf-list1.sourceforge.net with esmtp (Exim 3.31-VA-mm2 #1 (Debian)) id 16nhVc-0005RY-00 for ; Wed, 20 Mar 2002 06:56:12 -0800 To: nfs@lists.sourceforge.net, autofs@linux.kernel.org Errors-To: nfs-admin@lists.sourceforge.net List-Help: List-Post: List-Subscribe: , List-Id: Discussion of NFS under Linux development, interoperability, and testing. List-Unsubscribe: , List-Archive: An update to my previous posts: The problem re-occurred today - from /var/log/messages on a client: Mar 20 10:35:20 client automount[465]: attempting to mount entry /net/server1 Mar 20 10:35:37 client kernel: nfs: server server1 not responding, still trying Mar 20 10:38:57 client kernel: nfs: task 62879 can't get a request slot Mar 20 10:39:23 client kernel: nfs: server server1 OK Mar 20 10:39:23 client kernel: nfs: server server1 OK ... Mar 20 10:44:23 client1 automount[21355]: expired /net/server1 Accessing /net/server1 after this time gives "Permission denied" - until manually umount'ing. The machine server1 crashed or was rebooted between 10:35 and 10:39. The client is running a RedHat 2.4.7-10 based kernel - with the linux-2.4.7-seekdir.dif NFS client patch and a patch to ignore server fsid changes across reboots. This _seems_ to a problem with the server crashing - as other clients had exactly the same problem at the same time. Would other NFS client patches improve matters? Thanks James Pearson James Pearson wrote: > > Since sending my original message, I've found something on the kernel > list about a similar situation - see: > > http://www.geocrawler.com/archives/3/35/2001/12/2700/7351178/ > > I asked the original sender if he had any more info: > > > maybe the symptom is different, but the cause is the same, i don't know. > > If you write a script, that tries to unmount, you duplicate the functionality > > of the automounter daemon to a certain degree, what might lead to the same > > problems. I think the code path in fs/autofs4/root.c line 300+ is problematic: > > > > > > /* > > * If this dentry is unhashed, then we shouldn't honour this > > * lookup even if the dentry is positive. Returning ENOENT here > > * doesn't do the right thing for all system calls, but it should > > * be OK for the operations we permit from an autofs. > > */ > > if ( dentry->d_inode && d_unhashed(dentry) ) > > return ERR_PTR(-ENOENT); > > > > In my opinion it can happen that between the revalidate in 286 and this > > check for 'hashedness' another thread invalidates the entry and thus > > the syscall fails. When i find the time, i'll try to find out and fix. Possible, > > that it fixes also your problem, but currently i can't imagine a > > scenario including unavailable NFS-servers, that leads to this permission > > denied error. > > Could what is described be the problem? > > Is there a "fix"? > > Thanks > > James Pearson > > James Pearson wrote: > > > > I'm using autofs4 (autofs-4.0.0pre10) to mount a number of NFS mounts > > using a NIS map on machines running a RedHat based 2.4.7-10 kernel. > > > > Occasionally trying to access a mount point (that has been working fine) > > gives e.g: > > > > # cd /net/server1 > > cd: /net/server1: Permission denied > > > > This mount point never unmounts - even with sending SIGUSR1 to automount > > > > The only way I can unmount the file system is by explicitly using umount > > > > i.e. umount /net/server1 > > > > works OK and subsequent access to /net/server1 mounts the remote file > > system OK > > > > The remote "servers' in question tend to be other Linux workstations, > > that I _think_ have crashed (or been rebooted) while being mounted by > > the clients ... > > > > Is there anything I can do to fix this? > > > > In the meantime, I'm thinking of having a simple script that attempts to > > umount everything under the automount mount point every few minutes or > > so (by looking for these mounts in mtab) - is this likely to cause > > problems/confusion with automount? > > > > Thanks > > > > James Pearson > > > > _______________________________________________ > > NFS maillist - NFS@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/nfs _______________________________________________ NFS maillist - NFS@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/nfs