[sheepdog] [PATCH 2/2] farm: drop fcntl lock

[Christoph Hellwig]

On Mon, Jun 04, 2012 at 10:42:00AM +0800, Liu Yuan wrote:
> From: Liu Yuan <tailai.ly at taobao.com>
> 
> For a second thought, even QEMU can issue multiple requests to the same object
> we are guaranteed that those requests don't overlap on each other. Recovery
> code and IO code might access the same object, but the race is excluded by epoch
> so we don't need per-object lock at all for now.

How are we guaranteed that?  I'm pretty sure I debugged a problem with
the kernel AIO code a while ago where that was not the case when using
windows guests. (Using the qemu raw-posix backend, not sheepdog)