From: Peter Staubach <staubach@redhat.com>
Subject: Re: umount fails with device busy
Date: Thu, 23 Aug 2007 16:29:46 -0400
Message-ID: <46CDEE3A.3040809@redhat.com>
References: <20070823184544.237460@gmx.net> <46CDE805.4090909@oracle.com>
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Cc: nfs@lists.sourceforge.net
To: chuck.lever@oracle.com
In-Reply-To: <46CDE805.4090909@oracle.com>
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Chuck Lever wrote:
> z00t@gmx.net wrote:
>> Hi guys,
>>
>> I get the device busy error when I try to umount an NFS file system 
>> although there is no process with an open file on it (at least fuser 
>> -m /mnt/point and lsof +f -- /mnt/point don't find anything).
>>
>> To be more precise this only happens, when I run the umount right 
>> after stopping an application which has its executables and work 
>> directory on this file system. Running umount again some seconds 
>> later works fine.
>> I do not have any submounts under this mount point. There are no 
>> packet transmit or receive errors nor any NFS/RPC errors only a very 
>> small number of RPC retransmitts. So it seems that I have a stable 
>> environment. Client and server is SLES9 with 2.6.5-7.202.7-smp/X86_64.
>> I enabled NFS debug output and the only noticeable thing is, that 
>> some NFS operations are still ongoing after the application processes 
>> have already terminated:
>>
>>   Aug 23 08:25:23 marvin kernel: NFS reply getattr
>>   Aug 23 08:25:23 marvin kernel: NFS: nfs_update_inode(0:12/149296 
>> ct=1 info=0x6)
>>   Aug 23 08:25:23 marvin kernel: NFS: (0:12/149296) revalidation 
>> complete
>>   Aug 23 08:25:23 marvin kernel: nfs: flush(0:12/149296)
>>   Aug 23 08:25:23 marvin kernel: NFS: dentry_delete(bin/stop, 0)
>>   Aug 23 08:25:23 marvin kernel: NFS: revalidating (0:12/2)
>>   Aug 23 08:25:23 marvin kernel: NFS call  getattr
>>   Aug 23 08:25:23 marvin kernel: NFS reply getattr
>>   Aug 23 08:25:23 marvin kernel: NFS: nfs_update_inode(0:12/2 ct=1 
>> info=0x6)
>>   Aug 23 08:25:23 marvin kernel: NFS: (0:12/2) revalidation complete
>>   Aug 23 08:25:25 marvin kernel: NFS call  fsstat
>>   Aug 23 08:25:25 marvin kernel: NFS reply statfs: 0
>>   Aug 23 08:25:35 marvin kernel: NFS call  fsstat
>>   Aug 23 08:25:35 marvin kernel: NFS reply statfs: 0
>>   Aug 23 08:25:38 marvin kernel: NFS: 6368 initiated commit call
>>   Aug 23 08:25:38 marvin kernel: NFS: 6369 initiated commit call
>>   Aug 23 08:25:38 marvin kernel: NFS: 6370 initiated commit call
>>   Aug 23 08:25:38 marvin kernel: NFS: 6371 initiated commit call
>>   Aug 23 08:25:38 marvin kernel: NFS: 6368 nfs_commit_done (status 0)
>>   Aug 23 08:25:38 marvin kernel: NFS: commit (0:12/121805 3207@0)NFS: 
>> dentry_delete(log/mux_marvin.trc, 0)
>>   Aug 23 08:25:38 marvin kernel:  OK
>>   Aug 23 08:25:38 marvin kernel: NFS: 6369 nfs_commit_done (status 0)
>>   Aug 23 08:25:38 marvin kernel: NFS: commit (0:12/149304 2238@0)NFS: 
>> dentry_delete(log/pw_marvin_1.trc, 0)
>>   Aug 23 08:25:38 marvin kernel:  OK
>>   Aug 23 08:25:38 marvin kernel: NFS: 6370 nfs_commit_done (status 0)
>>   Aug 23 08:25:38 marvin kernel: NFS: commit (0:12/149297 2238@0)NFS: 
>> dentry_delete(log/pw_marvin_0.trc, 0)
>>   Aug 23 08:25:38 marvin kernel:  OK
>>   Aug 23 08:25:38 marvin kernel: NFS: 6371 nfs_commit_done (status 0)
>>   Aug 23 08:25:38 marvin kernel: NFS: commit (0:12/149295 965@0)NFS: 
>> dentry_delete(net.trc, 0)
>>   Aug 23 08:25:38 marvin kernel:  OK
>>   Aug 23 08:25:45 marvin kernel: NFS call  fsstat
>>   Aug 23 08:25:45 marvin kernel: NFS reply statfs: 0
>>   Aug 23 08:25:55 marvin kernel: NFS call  fsstat
>>
>> When I run umount during these ops I get an device busy. Any help 
>> would be very appreciated!
>
> This is normal and expected behavior.  One problem may be that your 
> server is slow, and thus there are RPCs left outstanding for a bit on 
> your client after your application exits.  The COMMIT calls from that 
> trace suggest that there is dirty data the client is writing back to 
> the server. 

It seems to me that this should not be the expected behavior unless
the file system is mounted "nocto".  Is it?

    Thanx...

       ps

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