Red Hat Bugzilla – Bug 169299
umount -l should work on hung NFS mounts with cached data
Last modified: 2007-11-30 17:07:20 EST
Description of problem:
Currently, umount -l only works if there is no cached data waiting to be
read/written to the mount point. This is a request to allow a way to forcefully
unmount, not caring about data loss. For example, if the NFS server has gone
away never to return, a hung NFS mount with data waiting should be allowed to be
unmounted. Requesting that this be considered for RHEL
Version-Release number of selected component (if applicable):
Initiate a write to the mountpoint, then take the NFS server down. umount -l
will report that the device is busy.
Steps to Reproduce:
1. dd if=/dev/zero of=/mnt/point
2. take down NFS server
3. umount -l /mnt/point
umount: /mnt/point: device is busy
umount -l succeeds
Created attachment 133014 [details]
I've incorporated the changes to my patch against latest nfs-utils, which can
be found at git://linux-nfs.org/nfs-utils
Created attachment 133149 [details]
lazy umount fix1
Patch in comment #6 is for util-linux. My patch in comment #11 is for nfs-utils
which is a complete patch that hasn't made it to the upstream + the changes
required for this bug fix. Alternatively you can use the attached patch which
is a fix for this bug on top of my patch for nfs-utils-1.0.9.
Created attachment 133403 [details]
The bug needs fixing at two places in this case.
1. nfs-utils - if its is compiled with --enable-mount
2. util-linux - if nfs-utils is NOT compiled with --enable-mount
--enable-mount configure option in nfs-utils generates mount.nfs binary which
overrides all the NFS mount/umount operations which otherwise are performed by
util-linux. Latest patches to nfs-utils in rawhide add this option, which has
also been sent upstream.
Fix 1 (for nfs-utils) is in comment #13. Attached patch, which is actually a
port of patch in comment #6 to latest util-linux, is fix 2 (for util-linux).
fixed in util-linux-2.12a-16.EL4.21
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release. Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products. This request is not yet committed for inclusion in an Update
This fix is available in the latest RHEL-4.5 Beta. If the customer is in
a position to test the beta, please ask for testing feedback. Thanks.
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.