mmap support with a dfuse-mounted posix conntainer



I have a very quick question about the below selection in Posix compliance. From a single DAOS client node, is mmap with MAP_SHARED supported from the client node against a file on a DAOS POSIX container, if it is mounted with dfuse to the client?
I've tried, but I get an error return from mmap. Below is the portion of my test code and the page size is 4KB.  Thanks in advance! 

#include <stdio.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <string.h>
#define FILE_SIZE 4096
int main(int argc, char *argv[]) {
    int fd;
    char *map;
    size_t map_size;
    fd = open(argv[1], O_CREAT | O_RDWR, 0665);
    if(fd < 0) {
        printf("Error : can't open file\n");
        return -1;
    map = (char*)mmap(NULL, map_size, PROT_WRITE, MAP_SHARED, fd, 0);
    if(map == MAP_FAILED) {
        printf("Error : mmap failed\n");
        return -1;

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