Two test programs are added. The run time is about 1min on my el7
instance.
The test script finishes up with a read/write mmap test on offline
extents to verify the data wait paths in those functions.
One program will perform vfs read/write and mmap read/write calls on
the same file from across 5 threads (mounts) repeatedly. The goal
is to assure there are no locking issues between read/write paths.
The second test program performs consistency checking on a file that is
repeatedly written/read using memory maps and normal reads and writes,
and the content is verified after every operation.
Signed-off-by: Auke Kok <auke.kok@versity.com>
