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[Cluster-devel] Re: [PATCH 2/2] Fix lockd panic



Neil Brown wrote:


If I'm reading this correctly, this bug is introduced by your previous
patch.
Depending on how you see the issue. From my end, I view this as the existing code has a "trap" and I fell into it. This is probably a chance to clean up this logic.

The important difference between the old code and the new code here is
that the old code tests "file->f_locks" while the new code iterates
through i_flock to see if there are any lockd locks.

f_locks is set to a count of lockd locks in nlm_traverse_locks which
*was* always called by nlm_inspect_file which is called immediately
before the code you are changing.
But since your patch, nlm_inspect_file does not always call
nlm_traverse_locks, so there is a chance that f_locks is wrong.

With this patch, f_locks it not used at all any more.
Yes, a fair description of the issue !

Introducing a bug in one patch and fixing in the next is bad style.
ok .....

Some options:

Have an initial patch which removes all references to f_locks and
includes the change in this patch.  With that in place your main
patch won't introduce a bug.  If you do this, you should attempt to
understand and justify the performance impact (does nlm_traverse_files
become quadratic in number of locks.  Is that acceptable?).

Change the first patch to explicitly update f_count if you bypass the
call to nlm_inspect_file.

something else???

Let's see what hch says in another email... will come back to this soon.

So NAK for this one in it's current form... unless I've misunderstood
something.

I expect this :)

-- Wendy


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