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Date: Mon, 24 Aug 2015 11:48:46 +0000
From: Daniel Shahaf <d.s@daniel.shahaf.name>
To: Stefan Fuhrmann <stefan.fuhrmann@wandisco.com>
Cc: Subversion Development <dev@subversion.apache.org>
Subject: Re: Issue #4588, part 1: FSFS access error
Message-ID: <20150824114846.GD7537@tarsus.local2>
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Stefan Fuhrmann wrote on Sun, Aug 23, 2015 at 20:38:03 +0100:
> This post focuses on the FSFS issue.  The good news is that
> confidence is high that the repo itself is correct and there
> has been no apparent data loss.  The error message indicates
> that something like Offset=L2P[L2P[Item]] or Offset=L2P[Offset]
> instead of Offset=L2P[item] happened.
...
> The lookup would start with a hit at the L2 DAG cache, mapping
> path+rev onto a noderev.  From there, everything is accessed
> using physical offsets until some item is not cached.  At that
> point, we would be trying to use an Offset instead of the Item
> index to address the f7 data.  Error.

So somehow we managed to cast an offset into an item.  Can we make the
code more strongly-typed?

Where is the "L2 DAG cache" in the code?  I assume it's
ffd->rev_node_cache, not fs_fs_dag_cache_t, correct?