From brandt@fokus.gmd.de  Thu Oct 26 03:15:35 2000
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Date: Thu, 26 Oct 2000 12:15:23 +0200 (CEST)
From: brandt@fokus.gmd.de
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To: FreeBSD-gnats-submit@freebsd.org
Subject: NFS client code blocks when reading a 2828 byte file via NFSv3
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>Number:         22309
>Category:       kern
>Synopsis:       NFS client code blocks when reading a 2828 byte file via NFSv3
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          closed
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Oct 26 03:20:01 PDT 2000
>Closed-Date:    Fri Oct 27 00:22:50 PDT 2000
>Last-Modified:  Fri Oct 27 00:24:20 PDT 2000
>Originator:     Hartmut Brandt
>Release:        FreeBSD 5.0-CURRENT i386
>Organization:
GMD Fokus
>Environment:

	NFS user directories are mounted via NFSv3 from a Auspex file server.

>Description:

	When reading a file of size 2828, 2829 (and probably a little longer)
	from the NFS server, the read blocks and the NFS files system appears
	blocked (other file systems from the same server may work).

	Tcpdump shows, that the read reply is fragmented into three IP
	fragments of size 1480, 1480 and 4. nfsstat shows that the client
	code is retrying the read. netstat -p ip shows that fragments are
	dropped because of timeouts. netstat -I xl0 shows no drops.

	It seems, that the IP code fails to reassemble the IP packet. When
	mounting the file system with NFSv2 everything works probably because
	now there are only two fragments instead of two.

	The problem appeared somewhere around the first decade of september.
	A generic kernel from beginning of september works ok.

>How-To-Repeat:

	Mount a NFS file system via NFSv3 from an Auspex server (another
	server will probably do it also). Create a file of size 2828 and
	try to read it.

>Fix:

	None.

	Using NFSv2 for the time beeing is at least a work-around.


>Release-Note:
>Audit-Trail:
State-Changed-From-To: open->closed 
State-Changed-By: ru 
State-Changed-When: Fri Oct 27 00:22:50 PDT 2000 
State-Changed-Why:  
Fixed in src/sys/netinet/ip_fw.c,v 1.147, thanks for the diagnosis! 

http://www.freebsd.org/cgi/query-pr.cgi?pr=22309 
>Unformatted:
