newfs locks entire machine for 20seconds

Steven Hartland killing at
Fri Feb 1 05:58:07 PST 2008

----- Original Message ----- 
From: "Steven Hartland" <killing at>

> ----- Original Message ----- 
> From: "Eric Anderson" <anderson at>
>> Wait - if it returns EAGAIN for a while, then look at that code above. 
>> It will hold the sysctl lock for some indefinite amount of time.  Maybe 
>> it should look like this instead:
>>    do {
>>        SYSCTL_LOCK();
>>        req.oldidx = 0;
>>        req.newidx = 0;
>>        error = sysctl_root(0, name, namelen, &req);
>>        SYSCTL_UNLOCK();
>>    } while (error == EAGAIN);
>>    if (req.lock == REQ_WIRED && req.validlen > 0)
>>        vsunlock(req.oldptr, req.validlen);
> Tried no difference unfortunately, possibly its give the closeness
> of the lock unlock its just reacquiring the lock straight after releasing
> it hence not giving the other thread chance to run / obtain the lock?

In an attempt to prove this is in fact the issue I've tried with the
locking around this code removed, yes dangerous but just as a test :)
It does indeed prevent the extended lockup so this is the right area.


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