ceph: fix error message on empty buffer
ceph: fix error message on empty buffer

Do not print the empty buffer to get a clean error message.

Signed-off-by: Sébastien Han <62d754cc350e84d3b1c32ae79f976f5348e74a40@redhat.com>

rook/rook,rook/rook,rook/nfs,rook/rook,rook/nfs,rook/rook,rook/rook,rook/nfs