1475960 – 'showmount -e' reports 'rpc mount export: RPC: Can't decode result'

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Bug 1475960 - 'showmount -e' reports 'rpc mount export: RPC: Can't decode result'

Summary: 'showmount -e' reports 'rpc mount export: RPC: Can't decode result'

Keywords:
Status:	CLOSED ERRATA
Alias:	None
Product:	Red Hat Enterprise Linux 6
Classification:	Red Hat
Component:	libtirpc
Sub Component:
Version:	6.9
Hardware:	Unspecified
OS:	Unspecified
Priority:	high
Severity:	medium
Target Milestone:	rc
Target Release:	---
Assignee:	Steve Dickson
QA Contact:	Zhi Li
Docs Contact:
URL:
Whiteboard:
Depends On:
Blocks:	1461138 1507140
TreeView+	depends on / blocked

Reported:	2017-07-27 15:52 UTC by Pierguido Lambri
Modified:	2021-09-09 12:28 UTC (History)
CC List:	11 users (show)
Fixed In Version:	libtirpc-0.2.1-15.el6
Doc Type:	If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed:	2018-06-19 05:13:38 UTC
Target Upstream Version:
Embargoed:

Attachments	(Terms of Use)

Links
System	ID	Private	Priority	Status	Summary	Last Updated
Red Hat Product Errata	RHBA-2018:1876	0	None	None	None	2018-06-19 05:13:58 UTC

Description Pierguido Lambri 2017-07-27 15:52:44 UTC

Description of problem:
When a RHEL6 NFS server export a bigger than usual export list, showmount reports the error in the $SUBJECT.

Version-Release number of selected component (if applicable):
nfs-utils >= 1.2.3-70.el6_8.1.x86_64

How reproducible:
Always

Steps to Reproduce:
1. Install RHEL6
2. Install nfs-utils >= 1.2.3-70.el6_8.1.x86_64
3. Export at least around 290 NFS exports
4. On the NFS client run 'showmount -e'

Actual results:
showmount reports 'rpc mount export: RPC: Can't decode result'

Expected results:
The list of exports should be listed

Additional info:
The issue doesn't happen if the NFS server is running nfs-utils <= 1.2.3-70.el6.x86_64

Comment 5 Yongcheng Yang 2017-07-28 03:24:26 UTC

(In reply to Pierguido Lambri from comment #0)

I cannot reproduce this issue followed the reproduce steps.
So maybe it needs some other specific settings.

> Steps to Reproduce:
> 1. Install RHEL6
> 2. Install nfs-utils >= 1.2.3-70.el6_8.1.x86_64
> 3. Export at least around 290 NFS exports
> 4. On the NFS client run 'showmount -e'
-----------------------------------------
[root@test-rhel6-machine ~]# rpm -q nfs-utils
nfs-utils-1.2.3-75.el6.x86_64
[root@test-rhel6-machine ~]# exportfs -ua
[root@test-rhel6-machine ~]# showmount -e $HOSTNAME 
Export list for test-rhel6-machine.rhts.eng.pek2.redhat.com:
[root@test-rhel6-machine ~]# for i in `seq 290`; do mkdir /export_test_$i && exportfs -i *:/export_test_$i 2>/dev/null; done
[root@test-rhel6-machine ~]# showmount -e $HOSTNAME 
Export list for test-rhel6-machine.rhts.eng.pek2.redhat.com:
<snip>
/export_test_286 *
/export_test_288 *
/export_test_290 *
<snip/>
[root@test-rhel6-machine ~]#

Comment 8 Yongcheng Yang 2017-08-14 02:50:50 UTC

Adding keyword "Regression" as nfs-utils previous (default 6.8)
version 1.2.3-70.el6 doesn't have this problem.

------------------------------------------
[root@hp-dl360g9-15 ~]# hostname 
hp-dl360g9-15.rhts.eng.pek2.redhat.com
[root@hp-dl360g9-15 ~]# rpm -q nfs-utils
nfs-utils-1.2.3-70.el6.x86_64
[root@hp-dl360g9-15 ~]# ssh yoyang.redhat.com "/usr/sbin/showmount -e hp-dl360g9-15.rhts.eng.pek2.redhat.com" | wc -l
yoyang.redhat.com's password: 
291

# Now update the nfs-utils
[root@hp-dl360g9-15 ~]# rpm -Uvh nfs-utils-1.2.3-70.el6_8.1.x86_64.rpm 
Preparing...                ########################################### [100%]
   1:nfs-utils              ########################################### [100%]
[root@hp-dl360g9-15 ~]# service nfs restart
Shutting down NFS daemon: [  OK  ]
Shutting down NFS mountd: [  OK  ]
Shutting down NFS quotas: [  OK  ]
Shutting down NFS services:  [  OK  ]
Shutting down RPC idmapd: [  OK  ]
Starting NFS services:  [  OK  ]
Starting NFS quotas: [  OK  ]
Starting NFS mountd: [  OK  ]
Starting NFS daemon: [  OK  ]
Starting RPC idmapd: [  OK  ]
[root@hp-dl360g9-15 ~]# ssh yoyang.redhat.com "/usr/sbin/showmount -e hp-dl360g9-15.rhts.eng.pek2.redhat.com"
yoyang.redhat.com's password: 
rpc mount export: RPC: Can't decode result <<<<<<<<<< Reproduced!
[root@hp-dl360g9-15 ~]# echo $?
1
[root@hp-dl360g9-15 ~]# rpm -q nfs-utils
nfs-utils-1.2.3-70.el6_8.1.x86_64

# Downgrading nfs-utils, then problem disappears
[root@hp-dl360g9-15 ~]# yum downgrade -y nfs-utils >/dev/null 2>&1
[root@hp-dl360g9-15 ~]# rpm -q nfs-utils
nfs-utils-1.2.3-70.el6.x86_64
[root@hp-dl360g9-15 ~]# ssh yoyang.redhat.com "/usr/sbin/showmount -e hp-dl360g9-15.rhts.eng.pek2.redhat.com" 
yoyang.redhat.com's password: 
Export list for hp-dl360g9-15.rhts.eng.pek2.redhat.com:
<snip...>
[root@hp-dl360g9-15 ~]# echo $?
0
[root@hp-dl360g9-15 ~]#

Comment 13 Steve Dickson 2017-11-08 19:02:55 UTC

I am not able to reproduce this via the instructions in Comment 8

Using rhel6-latest

nfs-utils-1.2.3-76.el6.x86_64
kernel-2.6.32-723.el6.x86_64

rhel6srv$ wc -l /etc/exports
300 /etc/exports

rhel6srv# service nfs restart
Shutting down NFS daemon:                                  [  OK  ]
Shutting down NFS mountd:                                  [  OK  ]
Shutting down NFS quotas:                                  [  OK  ]
Shutting down NFS services:                                [  OK  ]
Shutting down RPC svcgssd:                                 [  OK  ]
Shutting down RPC idmapd:                                  [  OK  ]
Starting RPC svcgssd:                                      [  OK  ]
Starting NFS services:                                     [  OK  ]
Starting NFS quotas:                                       [  OK  ]
Starting NFS mountd:                                       [  OK  ]
Starting NFS daemon:                                       [  OK  ]
Starting RPC idmapd:                                       [  OK  ]

rhel6srv# ssh steved@rhel6 "showmount -e rhel6srv" | wc -l
steved@rhel6's password: 
301

Note the one extra export is the banner showmount prints
"Export list for rhel6srv:"

Comment 14 Steve Dickson 2017-11-08 19:04:40 UTC

Could please try with the latest nfs-utils (1.2.3-76.el6)

Comment 16 Steve Dickson 2017-11-10 14:08:23 UTC

The needed upstream patch

commit a4fa582908b9c63957240cb0cb68b59d56244ef5
Author: Bodo Stroesser <bstroesser.com>
Date:   Thu Nov 6 13:26:00 2014 -0500

    write_vc: fix write retry loop for nonblocking mode

Comment 17 Steve Whitehouse 2017-12-01 09:26:09 UTC

SteveD, can you post this now if that is the correct patch?

Comment 23 Zhi Li 2017-12-13 02:34:38 UTC

Moving to VERIFIED according to test logs of comment #22.

Comment 28 errata-xmlrpc 2018-06-19 05:13:38 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.

https://access.redhat.com/errata/RHBA-2018:1876

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