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Re: NFSD tapset: how can I get filename from filehandles ?


>> I've tried a few things without success... such as:
>> 
>> 
>>     filename = @cast($argp, "nfsd3_writeargs",
>> "kernel:nfsd")->fh->fh_dentry->d_name->name
>> 
>> 
>> which ended with a segfault.

> OK, I'm going to need some details here.  First, what kernel are you
using?

I'm using Debian's 2.6.32.

 
> When you say a 'segfault', do you mean the stap executable segfaulted,
> or you got a kernel read fault, something like this:
> 
> ---
> ERROR: kernel read fault at 0x0000000000000034 (addr) near identifier
> '@cast' at /usr/local/share/systemtap/tapset/dentry.stp:41:15
> ---

You're right ! They were read faults.

 
> I'll include the script in a sec, but that is systemtap protecting me
> from crashing my kernel.  Instead of letting me read from that bogus
> address, systemtap errors out.  This is a good thing.

Ok, It is not obvious to me, but right, that's far better than a kernel
oops :) 
(I got one, experiencing the guru mode on that filename problem :p)


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