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Bug 1095943

Summary: unrelated Filesystem resources can block during stop when unresponsive nfs mounts are present
Product: Red Hat Enterprise Linux 6 Reporter: David Vossel <dvossel>
Component: resource-agentsAssignee: David Vossel <dvossel>
Status: CLOSED ERRATA QA Contact: Cluster QE <mspqa-list>
Severity: high Docs Contact:
Priority: unspecified    
Version: 6.6CC: agk, cluster-maint, djansa, fdinitto, mnovacek, sbradley
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: resource-agents-3.9.5-7.el6 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
: 1095944 (view as bug list) Environment:
Last Closed: 2014-10-14 05:01:04 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 1095944    
Attachments:
Description Flags
unit test none

Description David Vossel 2014-05-08 21:51:26 UTC 
Description of problem:

The Filesystem resource agent uses fuser to kill processes accessing the mount point during the stop operation. fuser is known to block when unresponsive nfs mounts are present on the system. This will cause completely unrelated Filesystem resources to fail during their stop operation (which in turn causes the node to be fenced).

We can avoid this by adopting similar logic used in the rgmanager fs-lib.sh based agents found in this issue.

https://bugzilla.redhat.com/show_bug.cgi?id=1014298


How reproducible:
100%


Steps to Reproduce:
1. mount a nfs share
2. kill the nfs server
3. attempt to use the Filesystem resource to manage a completely unrelated mount point. Have a process like 'tail' open a file on the mount point before stopping the resource so the mountpoint will be busy.

Actual results:
Filesystem agent blocks for the entire duration of the nfs timeout period during the fuser detection of the pids accessing the mount point

Expected results:
Filesystem should not block because of the unresponsive nfs mount.  The agent should be able to kill the 'tail' pid allowing the filesystem to unmount properly.
Comment 1 David Vossel 2014-05-08 21:53:47 UTC 
upstream patch related to this issue.

https://github.com/davidvossel/resource-agents/commit/c04d89842bb11e975e71fa1d7d632ec2eb2bd055
Comment 2 David Vossel 2014-05-08 21:58:11 UTC 
Created attachment 893796 [details]
unit test

This script tests the new force_unmount=safe option the patch adds.

unit-test by running the following.
./bind-test.sh /usr/lib/ocf/resource.d/heartbeat/Filesystem 

-- Vossel
Comment 4 michal novacek 2014-07-29 12:25:49 UTC 
I have verified with unittest from comment #2 that independent filesystems
would not block each other with resource-agents-3.9.5-11.el6.x86_64

-----

# rpm -q resource-agents
resource-agents-3.9.5-11.el6.x86_64


# ./bind-test_v2.sh 
umount: /root/testsrc: not found
umount: /root/target: not found
<debug>  Checking fs "testrsc", Level 
[bind-mount.sh] Checking fs "testrsc", Level 
<err>    default: /root/testsrc is not mounted on /root/target
[bind-mount.sh] default: /root/testsrc is not mounted on /root/target
<info>   /root/testsrc is not mounted
[bind-mount.sh] /root/testsrc is not mounted
<info>   mounting /root/testsrc on /root/target
[bind-mount.sh] mounting /root/testsrc on /root/target
<debug>  mount  -o bind /root/testsrc /root/target
[bind-mount.sh] mount  -o bind /root/testsrc /root/target
<debug>  Checking fs "testrsc", Level 
[bind-mount.sh] Checking fs "testrsc", Level 
<debug>  /root/testsrc already mounted
[bind-mount.sh] /root/testsrc already mounted
<info>   unmounting /root/target
[bind-mount.sh] unmounting /root/target
<info>   /root/testsrc is not mounted
[bind-mount.sh] /root/testsrc is not mounted
<debug>  Checking fs "testrsc", Level 
[bind-mount.sh] Checking fs "testrsc", Level 
<err>    default: /root/testsrc is not mounted on /root/target
[bind-mount.sh] default: /root/testsrc is not mounted on /root/target
<info>   mounting /root/testsrc on /root/target
[bind-mount.sh] mounting /root/testsrc on /root/target
<debug>  mount  -o bind /root/testsrc /root/target
[bind-mount.sh] mount  -o bind /root/testsrc /root/target
starting bg process to hold target file open
this is test file
starting bg process to hold target file open
<debug>  Checking fs "testrsc", Level 
[bind-mount.sh] Checking fs "testrsc", Level 
<info>   unmounting /root/target
[bind-mount.sh] unmounting /root/target
umount: /root/target: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))
<debug>  umount failed: 1
[bind-mount.sh] umount failed: 1
<warning>Sending SIGTERM to processes on /root/target
[bind-mount.sh] Sending SIGTERM to processes on /root/target
<info>   unmounting /root/target
[bind-mount.sh] unmounting /root/target
./bind-test_v2.sh: line 31: 16639 Terminated              tail -f "$target/testfile"
./bind-test_v2.sh: line 31: 16644 Terminated              tail -f "$tmpfile"
<debug>  Checking fs "testrsc", Level 
[bind-mount.sh] Checking fs "testrsc", Level 
<err>    default: /root/testsrc is not mounted on /root/target
[bind-mount.sh] default: /root/testsrc is not mounted on /root/target
PASSED
Comment 5 errata-xmlrpc 2014-10-14 05:01:04 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHBA-2014-1428.html