Re: Union mount and lockdep design issues

From: David Howells
Date: Wed Jul 13 2011 - 08:02:41 EST


Miklos Szeredi <miklos@xxxxxxxxxx> wrote:

> Overlayfs never locks both upper and lower at the same time, which means
> there's no AB-BA locking dependency. The lock orderings are:

What you're talking about is not analogous to the situation I'm seeing with
unionmount.

You actually have three filesystems in overlayfs. The interaction between
overlayfs-and-upperfs and overlayfs-and-lowerfs is the equivalent in
unionmount terms to upperfs-and-lowerfs. This is where the lockdep issue
lies.

David
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