ompi/file: add a muteex to the ompi_file_t structure

Adding a mutex to thje ompi_file_t structure allows to have a per-file handle
mutex lock for both ROMIO and OMPIO. I double checked that the size of the
ompi_file_t structure is still below the size of the predefined_file_t structure,
so we should be good from the backward compatibility perspective.

Author: edgargabriel

ompi/file/file.c

@@ -14,6 +14,7 @@
  * Copyright (c) 2009-2012 Cisco Systems, Inc.  All rights reserved.
  * Copyright (c) 2015      Research Organization for Information Science
  *                         and Technology (RIST). All rights reserved.
+ * Copyright (c) 2016      University of Houston. All rights reserved.
  * $COPYRIGHT$
  *
  * Additional copyrights may follow
@@ -106,6 +107,7 @@ int ompi_file_open(struct ompi_communicator_t *comm, const char *filename,
         return OMPI_ERR_OUT_OF_RESOURCE;
     }
 
+
     /* Save the params */
 
     file->f_comm = comm;
@@ -131,6 +133,9 @@ int ompi_file_open(struct ompi_communicator_t *comm, const char *filename,
         return OMPI_ERR_OUT_OF_RESOURCE;
     }
 
+    /* Create the mutex */
+    OBJ_CONSTRUCT(&file->f_mutex, opal_mutex_t);
+
     /* Select a module and actually open the file */
 
     if (OMPI_SUCCESS != (ret = mca_io_base_file_select(file, NULL))) {
@@ -150,6 +155,9 @@ int ompi_file_open(struct ompi_communicator_t *comm, const char *filename,
  */
 int ompi_file_close(ompi_file_t **file)
 {
+
+    OBJ_DESTRUCT(&(*file)->f_mutex);
+
     (*file)->f_flags |= OMPI_FILE_ISCLOSED;
     OBJ_RELEASE(*file);
     *file = &ompi_mpi_file_null.file;

ompi/file/file.h

@@ -14,6 +14,7 @@
  * Copyright (c) 2009-2012 Cisco Systems, Inc.  All rights reserved.
  * Copyright (c) 2015      Research Organization for Information Science
  *                         and Technology (RIST). All rights reserved.
+ * Copyright (c) 2016      University of Houston. All rights reserved.
  * $COPYRIGHT$
  *
  * Additional copyrights may follow
@@ -78,6 +79,10 @@ struct ompi_file_t {
         indicates what member to look at in the union, below) */
     mca_io_base_version_t f_io_version;
 
+    /** Mutex to be used to protect access to the selected component
+        on a per file-handle basis */
+    opal_mutex_t f_mutex;
+
     /** The selected component (note that this is a union) -- we need
         this to add and remove the component from the list of
         components currently in use by the io framework for