io-threads: Sanity check worker thread idx
io-threads: Sanity check worker thread idx

This patch adds sanity check for the ordered worker thread index
returned from the inode's context. If the index is corrupted we
STACK_UNWIND with ECANCELED.

Signed-off-by: Anand V. Avati <6a1810c170bd423868ce2e225ecea39d80cade0f@amp.gluster.com>

Kaushikbv/Gluster,Kaushikbv/Gluster,Kaushikbv/Gluster