Fixes a NULL pointer dereference.
Reported-by: NArnav Dawn <a.dawn@samsung.com>
Signed-off-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>