Bug 491166

Summary:	Regression: 2.6.27 kernel's nfs does not communicate properly with older AIX systems
Product:	[Fedora] Fedora	Reporter:	Elliott Johnson <elliott>
Component:	kernel	Assignee:	Kernel Maintainer List <kernel-maint>
Status:	CLOSED NOTABUG	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	low	Docs Contact:
Priority:	low
Version:	9	CC:	kernel-maint, quintela
Target Milestone:	---
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Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2009-03-20 16:12:19 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Elliott Johnson 2009-03-19 17:03:19 UTC

Description of problem:

After an upgrade from fc8 to fc10 one of our central systems no longer communicated properly with our older AIX systems, so we tested out other fc9 and fc10 machines against these AIX Version 5.1 boxes and all 2.6.27 systems are incompatable.

All traffic is received by the AIX machines as visible by a tcpdump, directory listings and such work fine, but reads are ignored and hang.  Trying the same operation on a fc8 machine with kernel 2.6.26.8-57.fc8 works without problem

Version-Release number of selected component (if applicable):

The regression has shown itself on our three newer fedora installs fc9 (kernel 2.6.27.15-78.2.23.rc8.x86_64) and two fc10 installs (one fresh using kernel 2.6.27.19-170.2.35.fc10.x86_64 and one upgrade using kernel  2.6.27.19-170.2.35.fc10.i686)

How reproducible:

Assuming the availability of a AIX 5.1 machine, very reproducible. 

Steps to Reproduce:
1. Do a typical nfs configuration (/etc/exports, start nfs, mount a share)
2. Do a read operation, like `file /path/to/file/in/share`
  
Actual results:

The read hangs.  Tcpdump shows the read request go through and a response, but the older AIX system does nothing with it.

Expected results:

For it to behave like fc8 with its 2.6.26 kernel.

Additional info:

I'm not exactly sure what kind of information you'll need to debug this.  I'll provide whatever is required.

Thanks.

Comment 1 Elliott Johnson 2009-03-19 22:49:45 UTC

My co-worker has corrected a few of my points:

* I use the term "older AIX systems".  I should point out that they are our only AIX systems.

* Not all reads are ignored.  It only happens on some files and I'll try to find a correlation as to why those files are different than others.

* Re: "Tcpdump shows the read request go through and a response, but
the older AIX system does nothing with it."    There is no
response... that's the problem.

Comment 2 Elliott Johnson 2009-03-20 16:12:19 UTC

We've found the issue to be with AIX.  When mounting the nfs partition specifying 32KB read/write sizes it functions as expected.