kern/92785: Using exported filesystem on OS/2 NFS client causes filesystem freeze

[Luke]

>Number:         92785
>Category:       kern
>Synopsis:       Using exported filesystem on OS/2 NFS client causes filesystem freeze
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Feb 04 02:50:02 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     Luke
>Release:        FreeBSD 6.0-RELEASE
>Organization:
>Environment:
FreeBSD 6.0-RELEASE i386
>Description:
It was discovered that using OS/2's NFS client to access an exported filesystem on a FreeBSD system causes the exported filesystem to 'freeze' whenever a file is accessed or dismounted on the OS/2 client.

This freeze causes any command (ls, etc) that tries to use the filesystem in question to hang and be unkillable (they seem to be stuck in the UFS state, according to 'ps axl' after doing a 'shutdown now'.  Trying to umount the filesystem fails, claiming it is busy.  It is impossible to properly shut down the system when this happens.

Interestingly enough, the OS/2 client can continue to access files (copy, delete, etc) on the 'frozen' filesystem, as if it had some sort of exclusive access.

This problem was not seen on an older release of FreeBSD I used (4.9) with the same NFS client.

I do not know if this problem is exclusive to the OS/2 client.

Additional info:
Running ULE scheduler with i386 SMP kernel (AMD64 chip in 32bit mode).
>How-To-Repeat:
Export a UFS2 (softupdates) filesystem for NFS on the FreeBSD system.
With the OS/2 NFS client, mount that filesystem and copy a file over to it.  Unmount the filessytem from the OS/2 client (this will probably fail).
On the FreeBSD system, attempt to access the exported filesystem (ls, etc.).  Note the 'freeze'.

Use OS/2 NFS client version:
IBM NFS for OS/2
UMOUNT Version 3.99
Release:  m17

On OS/2 Warp 4

C:\MPTN\SYSLEVEL.MPT
                    IBM OS/2 TCP/IP Stack
Version 6.01     Component ID 5639B1700
Current CSD level: WR08705
Prior   CSD level: WR08701

C:\MPTN\SYSLEVEL.NFS
                    NFS for TCP/IP on OS/2
Version 3.00.3     Component ID 5639A6602
Current CSD level: UN02205
Prior   CSD level: UN02200

>Fix:
              
>Release-Note:
>Audit-Trail:
>Unformatted: