VFS: fix aborting queued requests after FS crash
The new asserts from git-
29e004d exposed an issue in how VFS handles
aborting file system (FS) requests that are queued for a FS (as
opposed to sent to it) when that FS crashes. In that scenario, the
queued worker has its w_task set to NONE, because there is no ongoing
communication. However, worker_stop() is called on it regardless,
which used to abort the request only if w_task was not set to NONE,
leading to an improperly aborted request, a warning, and a VFS crash a
bit later. This patch changes worker_stop() so that w_task need not
be set to a valid endpoint for FS requests to be properly aborted.
Change-Id: Ib73db285e689ae4742b15cba26137bf340bc303b