Command allocation is the thing that takes the longest in the main i/o
path, so check for controller lockup immediately after this to prevent
submitting commands to locked up controller as much as possible.
Reviewed-by: Scott Teel <scott.teel@pmcs.com> Signed-off-by: Don Brace <don.brace@pmcs.com> Signed-off-by: Christoph Hellwig <hch@lst.de>