[sheepdog] [PATCH] sheepdog: fix confused return values

[Liu Yuan]

On Fri, Feb 13, 2015 at 11:45:42AM +0800, Liu Yuan wrote:
> From: Liu Yuan <liuyuan at cmss.chinamobile.com>
> 
> These functions mix up -1 and -errno in return values and would might cause
> trouble error handling in the call chain.
> 
> This patch let them return -errno and add some comments.
> 
> Reported-by: Markus Armbruster <armbru at redhat.com>
> Signed-off-by: Liu Yuan <liuyuan at cmss.chinamobile.com>

Cc Kevin and Stefan