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Date: Wed, 02 Jan 2008 06:38:41 -0600
From: Eric Anderson <anderson@freebsd.org>
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To: Danny Braniss <danny@cs.huji.ac.il>
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Cc: freebsd-hackers@freebsd.org
Subject: Re: nfs v2/v3 and diskless boot problem
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Danny Braniss wrote:
> there is an undocumented option:
> 	boot-nfsroot-options
> that the diskeless boot can use. I tried 
> 	boot-nfsroot-options = "nfsv3"
> since the pxeboot does the initial mount via nfsv2, and this has at least
> one problem: removing a file from the readonly / will hang the system.
> 
> so, the remount to v3 works in the case that the root is served by a Freebsd
> nfs server, but fails if it's NetAPP. The reason is that the v2 filehandle
> is 32 bytes, and when switching to V3 it becomes 28bytes - sizeof(fhandle_t).
> This is not liked by the NetApp, which correctly gives error 1001: BADHANDLE 
> :-)
> 
> While I'm trying to come up with a solution, I am wondering if someone
> can shed some light:
>  - is sizeof(fhandle_t) == 28 bytes is mystical, or changing it to
>    32 bytes will start WW3?


NFSv3 file handles (by spec) can be up to 64bytes.

I'm not 100% sure what is happening, but it sounds like the file handle 
for the mount point or maybe one of the directories is not getting reset 
on remount.

When do you get the BADHANDLE error?  Can you capture a 
tshark/wireshark/tcpdump of the remount and error?

Eric