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

@@ -236,28 +236,41 @@
 #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) {
+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
-  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));
+  if (allocate == true) {
+    if (os::allocate_file(fd, size) != 0) {
     return NULL;
   }
+  }
 
-  int prot = PROT_READ | PROT_WRITE;
+  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, 0);
 
+  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) {