Bug 1435901

Summary:	mount.nfs: starts mount negation with v4.2 it should be v4.1
Product:	Red Hat Enterprise Linux 7	Reporter:	Steve Dickson <steved>
Component:	nfs-utils	Assignee:	Steve Dickson <steved>
Status:	CLOSED ERRATA	QA Contact:	Yongcheng Yang <yoyang>
Severity:	unspecified	Docs Contact:	Milan Navratil <mnavrati>
Priority:	unspecified
Version:	7.4	CC:	andros, bfields, eguan, fs-qe, jiyin, mnavrati, steved
Target Milestone:	rc
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	nfs-utils-1.3.0-0.37.el7	Doc Type:	No Doc Update
Doc Text:	undefined	Story Points:	---
Clone Of:		Environment:
Last Closed:	2017-08-01 19:50:23 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:	1385242

Description Steve Dickson 2017-03-25 18:25:54 UTC

Description of problem:

With bug 1375259 the mounting negation was bumped up
to NFS v4.2. This caused problems that are described 
in bug 1406885 an well as cause a mount renegotiation
on every with all the major enterprise server. This 
was noticed at this year's connectathon. 

The reason being they don't support v4.2 and have no
plans to do so in the foreseeable futures. 

Since the majority of these type of servers are our
customer's servers and I don't think these renegotiation
will scale very well on huge home directory servers, 
we need to dial the negation back to start at v4.1
a version that is supported by those types of servers.

Comment 3 Yongcheng Yang 2017-03-27 10:07:22 UTC

Please note there maybe need some update for man page NFS(5).

Just a glance about it:

$ man nfs | col -b | grep -A2 "nfsvers=n"
nfsvers=n
The NFS protocol version number used to contact the server's NFS service.  If the server does not support the requested version, the mount request fails.  If this option is not specified, the client negotiates a suitable version with the server, trying version 4 first, version 3 second, and version 2 last.

Comment 4 J. Bruce Fields 2017-03-27 14:29:18 UTC

(In reply to Steve Dickson from comment #0)
> With bug 1375259 the mounting negation was bumped up
> to NFS v4.2. This caused problems that are described 
> in bug 1406885

Agreed, we should start negotiation with 4.1 instead.

> Since the majority of these type of servers are our
> customer's servers and I don't think these renegotiation
> will scale very well on huge home directory servers, 
> we need to dial the negation back to start at v4.1
> a version that is supported by those types of servers.

However, minor version negotiation should be cheap.  The protocol only requires a single extra round trip on mount.  Our current implementation also requires a new TCP connection, and if that causes problems, we should fix it.

Comment 9 Steve Dickson 2017-06-09 15:00:08 UTC

*** Bug 1375259 has been marked as a duplicate of this bug. ***

Comment 14 errata-xmlrpc 2017-08-01 19:50:23 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-2017:2233