Bug 458911 - umount failed after umount the NFS share
umount failed after umount the NFS share
Product: Red Hat Enterprise Linux 4
Classification: Red Hat
Component: kernel (Show other bugs)
All Linux
medium Severity medium
: rc
: ---
Assigned To: Jeff Layton
Martin Jenner
Depends On:
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Reported: 2008-08-13 01:25 EDT by masanari iida
Modified: 2014-06-18 03:38 EDT (History)
1 user (show)

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Fixed In Version:
Doc Type: Bug Fix
Doc Text:
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Last Closed: 2008-08-19 07:25:42 EDT
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Regression: ---
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RHEL 7.3 requirements from Atomic Host:
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Description masanari iida 2008-08-13 01:25:32 EDT
Description of problem:
NFS exported filesystem can not be unmuont even though
all nfs-clients unmount the share.

Version-Release number of selected component (if applicable):
RHEL4.7 (kernel 2.6.9-78)

How reproducible:

Steps to Reproduce:
1. Setup NFS server.
 mount /nfs.
 setup /etc/exports dir.
 Start nfs daemon. 

2. Mount the NFS share from NFS client.
 # mount NFS_Server:/nfs  /mnt

This NFS mount succesful.

3. Umount the NFS share from NFS client.
 # umount /mnt

This NFS umount succesful.

4. Umount /nfs on NFS Server.
 # umount /nfs

Actual results:
Umount fail with following message.

# umount /nfs
umount: /nfs: device is busy
umount: /nfs: device is busy

Expected results:
umount successful without error message.

(1) umount -l /nfs 
(2) /etc/init.d/nfs restart, then umount /nfs

Additional info:
When umount failed,
 lsof shows no process accessing /nfs
 fuser shows no process accessing /nfs
Comment 1 masanari iida 2008-08-13 01:46:56 EDT

Another workaround that I just found was, 
remove export entry in kernel before issue umount.

# exportfs -au 
# umount /nfs

So, my question would be,
" Umount a file system while it was exported by NFS
 got faild. Is this a bug or expected? "

Comment 2 Jeff Layton 2008-08-19 07:25:42 EDT
This is expected. An actively exported a filesystem has an active reference and cannot be unmounted. I'm going to close this as NOTABUG. Please reopen it if you have further questions.

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