Re: [patch 11/33] fs: dcache scale subdirs

[Peter Zijlstra]

On Tue, 2010-06-22 at 19:03 -0700, john stultz wrote:

> > Well, you make lockdep very unhappy by locking multiple dentries
> > (unbounded number) all in the same lock class.
> 
> So.. Is there a way to tell lockdep that the nesting is ok (I thought
> that was what the spin_lock_nested call was doing...)? 

spin_lock_nested() allows you to nest a limited number of locks (up to
8, although the usual case is 1).

> Or is locking a (possibly quite long) chain of objects really just a
> do-not-do type of operation? 

Usually, yeah. It would be really nice to do this another way (also for
scalability, keeping a large subtree locked is bound to to lead to more
contention).
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