write_proc is not invoked when written from userspace - linux

Question

I am trying to understand procfs for communication between userspace and kernel module. My module has basic two functions for procfs write_proc, driver_mmap.
I call multiple times write_proc by calling fputs("123456789",fd). where fd is file descriptor to procfs entry in /proc directory. But I don't see write_proc called multiple time. Code is attached by here.
<code>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/slab.h>
#include <sound/core.h>
#include <sound/initval.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/proc_fs.h>
#include <asm/uaccess.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/mm.h> /* mmap related stuff */
#define BUF_SIZE 64 * 1024
int *MmapBuffer;
int Factor = 1;
static int write_proc(struct file *filp, int *buf, size_t count, loff_t *offp)
{
int rc,i;
printk("in Write \n");
for (i = 1; i <= 16*1024 ; i++)
MmapBuffer[i-1] = (i+1)*Factor;
Factor++;
return count;
}
static int driver_mmap(struct file *file, struct vm_area_struct *vma)
{
int ret;
vma->vm_flags |= VM_LOCKED|VM_SHARED;
ret = remap_pfn_range(vma, vma->vm_start,
virt_to_phys(MmapBuffer) >> PAGE_SHIFT,
vma->vm_end-vma->vm_start, vma->vm_page_prot);
if(ret != 0)
printk("MMAP Failed \n");
SetPageReserved(virt_to_page(MmapBuffer));
printk("MMAP Succeeded \n");
return 0;
}
// file operations
struct file_operations proc_fops =
{
.write = write_proc,
.mmap = driver_mmap,
};
// init module
int init_module_test(void)
{
printk("<1>Hello world\n");
MmapBuffer = kzalloc(BUF_SIZE,__GFP_COLD|GFP_DMA);
if(MmapBuffer == NULL)
printk("Kzalloc failed. reduce buffer size \n");
proc_create ("Test_fs",0,NULL, &proc_fops);
return 0;
}
// exit module
void cleanup_module_test(void)
{
kfree(MmapBuffer);
remove_proc_entry ("Test_fs", NULL);
printk("Goodbye world\n");
}
module_init(init_module_test);
module_exit(cleanup_module_test);
MODULE_LICENSE("GPL");
</code>
Application code
<code>
#include<stdio.h>
#include<stdlib.h>
#include<sys/mman.h>
#include<errno.h>
#include <fcntl.h>
int main(void)
{
int fd;
int i,j;
int *msg ;
printf("Allocation started \n ");
msg=(int*)malloc(64*1024);
if(msg == NULL)
printf("Allocation failed \n");
//unsigned int *addr;
printf("Starting opening \n ");
if((fd=open("/proc/Test_fs", O_RDONLY ))<0)
{
printf("File not opened ");
}
printf("Starting mapping \n ");
msg = mmap(NULL, 64*1024, PROT_READ, MAP_SHARED , fd, 0);
printf("done from module \n ");
if(msg == MAP_FAILED)
{
printf("MAP failed and error is %s", strerror(errno));
return 0;
}
close(fd);
printf("Successful mapping");
FILE *f;
f=fopen("/proc/Test_fs", "wr");
if(!f)
{
printf("File not opened ");
}
for (j = 0; j < 10 ; j++)
{
if(fputs("1234567890,",f) <= 0)
printf("write failed, ");
for (i = 0; i < 16*1024 ; i++)
printf("%d, ", msg[i]);
printf("\n \n done \n \n ");
}
fclose(f);
return 0;
}
</code>