use O_DIRECT open file, when read will hang.

[Hugang]

Hello all:

Steps to reproduce:

rm -f /tmp/1.log
touch /tmp/1.log
echo << EOF > /tmp/hang.c 
#include <sys/types.h>
#include <asm/fcntl.h>

main()
{
        int i;
        char buf[1025];

        i = open("/tmp/1.log", O_RDONLY | 040000, 0);
        if ( i != -1) {
                read(i, buf, 1);
        }
        printf("'%s'", buf);
}
EOF
gcc -o /tmp/hang /tmp/hang.c
/tmp/hang


-- 
Hu Gang / Steve
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