Minimize locking duration for decommitLock

[cshung]

No description provided.

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[Maoni0]

as discussed, this actually shouldn't be done since you'll hit a deadlock when multiple user threads call refresh.

[Maoni0]

ahh, I thought this was for a different problem where we talked about the lock order. I see this is actually about moving the lock to be around the verification, then yes, this is the right thing to do.