Reduce memory footprint of the dio_read test

The runtest file modified in ac6af27 ("Create dio_read.c test") did
require half an hour to complete and used ~3.5GB of RAM, which would
trigger OOM on memory constrained systems.

This patch reduces both read and write buffer size, as well as the file
size, so test will take few minutes to complete and the memory footprint
was reduced to ~50MB.

Fixes: ac6af27 ("Create dio_read.c test")
Signed-off-by: Andrea Cervesato <[email protected]>
Acked-by: Martin Doucha <[email protected]>
Reviewed-by: Cyril Hrubis <[email protected]>

Author: acerv

runtest/ltp-aiodio.part4

@@ -62,7 +62,7 @@ DIT002 dio_truncate
 #Running read_checkzero
 #gread_checkzero
 #Running dio_read
-DOR000 dio_read -n 1 -i 100
-DOR001 dio_read -n 10 -i 30
-DOR002 dio_read -n 20 -i 15
-DOR003 dio_read -n 100 -i 4
+DOR000 dio_read -n 1 -i 100 -r 512k -w 512k -s 32M
+DOR001 dio_read -n 10 -i 30 -r 512k -w 512k -s 32M
+DOR002 dio_read -n 20 -i 15 -r 512k -w 512k -s 32M
+DOR003 dio_read -n 100 -i 4 -r 512k -w 512k -s 32M