os/posix/os_posix.cpp

rev 1 : G1GC+POGC+NVDIMM Patch with latest comments incorporated from all.
rev 2 : Removed fcntl and fixed hotspot else violation

*** 236,263 ****
  #else
    return posix_fallocate(fd, offset, len);
  #endif
  }
  
  // Map the given address range to the provided file descriptor.
! char* os::map_memory_to_file(char* base, size_t size, int fd) {
    assert(fd != -1, "File descriptor is not valid");
  
    // allocate space for the file
!   int ret = util_posix_fallocate(fd, 0, (off_t)size);
!   if (ret != 0) {
!     vm_exit_during_initialization(err_msg("Error in mapping Java heap at the given filesystem directory. error(%d)", ret));
      return NULL;
    }
  
!   int prot = PROT_READ | PROT_WRITE;
    int flags = MAP_SHARED;
    if (base != NULL) {
      flags |= MAP_FIXED;
    }
-   char* addr = (char*)mmap(base, size, prot, flags, fd, 0);
  
    if (addr == MAP_FAILED) {
      warning("Failed mmap to file. (%s)", os::strerror(errno));
      return NULL;
    }
    if (base != NULL && addr != base) {
--- 236,276 ----
  #else
    return posix_fallocate(fd, offset, len);
  #endif
  }
  
+ // Allocates space for the file on diven device
+ int os::allocate_file(int file_desc, size_t size) {
+    // allocate space for the file
+    if (file_desc == -1) {
+      vm_exit_during_initialization(err_msg("Invalid file descriptor passed (%d)", file_desc));
+    }
+   int ret = util_posix_fallocate(file_desc, 0, (off_t)size);
+   if (ret != 0) {
+       vm_exit_during_initialization(err_msg("Could not allocate file to map Java heap on given filesystem... error(%d)", ret));
+   }
+   return ret;
+ }
+ 
  // Map the given address range to the provided file descriptor.
! char* os::map_memory_to_file(char* base, size_t size, int fd, int offset, bool exec, bool allocate) {
    assert(fd != -1, "File descriptor is not valid");
  
    // allocate space for the file
!   if (allocate == true) {
!     if (os::allocate_file(fd, size) != 0) {
        return NULL;
      }
+   }
  
!   int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
    int flags = MAP_SHARED;
    if (base != NULL) {
      flags |= MAP_FIXED;
    }
  
+   char* addr = (char*)mmap(base, size, prot, flags, fd, offset);
    if (addr == MAP_FAILED) {
      warning("Failed mmap to file. (%s)", os::strerror(errno));
      return NULL;
    }
    if (base != NULL && addr != base) {