The FIEMAP ioctl is more efficient and doesn't require root
privileges. So if it is available, use it in preference to repeated
FIBMAP calls.
Signed-off-by: Kalpak Shah <kalpak.shah@sun.com>
Signed-off-by: Andreas Dilger <adilger@sun.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>