(1) mkostemp with O_DIRECT in flags can fail, leaving a temporary file:

Apparently, O_DIRECT is not working on top of LVM. The problem is
in this case mkostemp() creates the temporary file but still returns
an error, and the temp file is not removed:

 $ ls
 ioping  ioping.1  ioping.c  ioping.o  ioping.spec  Makefile
 $ strace ./ioping -D .
 ....
 open("./ioping.UFuMHz", O_RDWR|O_CREAT|O_EXCL|O_DIRECT, 0600) = -1 EINVAL (Invalid argument)
 ....
 $ ls
 ioping  ioping.1  ioping.c  ioping.o  ioping.UFuMHz  ioping.spec  Makefile

Solution -- do not use flags, apply those later using fcntl()

(2) While trying to rebuild on centos5:

 cc -c -o ioping.o ioping.c -std=c99 -g -Wall -Wextra -pedantic -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64
 ioping.c: In function 'main':
 ioping.c:369: warning: implicit declaration of function 'mkostemp'
Signed-off-by: Kir Kolyshkin <kir@openvz.org>