[svn-r17365] Description:

	Final merge of changes from sblock_mdc branch back to trunk.  The superblock is now managed by the metadata cache.

Tested on:
        FreeBSD/32 6.3 (duty) in debug mode
        FreeBSD/64 6.3 (liberty) w/C++ & FORTRAN, in debug mode
        Linux/32 2.6 (kagiso) w/PGI compilers, w/C++ & FORTRAN, w/threadsafe,
                                in debug mode
        Linux/64-amd64 2.6 (smirom) w/Intel compilers w/default API=1.6.x,
                                w/C++ & FORTRAN, in production mode
        Solaris/32 2.10 (linew) w/deprecated symbols disabled, w/C++ & FORTRAN,
                                w/szip filter, in production mode
        Linux/64-ia64 2.6 (cobalt) w/Intel compilers, w/C++ & FORTRAN,
                                in production mode
        Linux/64-ia64 2.4 (tg-login3) w/parallel, w/FORTRAN, in production mode
        Mac OS X/32 10.5.8 (amazon) in debug mode
        Mac OS X/32 10.5.8 (amazon) w/C++ & FORTRAN, w/threadsafe,
                                in production mode

31 files changed, 1681 insertions, 1206 deletions

diff --git a/MANIFEST b/MANIFEST
index f877576..191bcab 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -524,6 +524,7 @@
 ./src/H5Fquery.c
 ./src/H5Fsfile.c
 ./src/H5Fsuper.c
+./src/H5Fsuper_cache.c
 ./src/H5Fpkg.h
 ./src/H5Fprivate.h
 ./src/H5Fpublic.h
diff --git a/src/H5AC.c b/src/H5AC.c
index d613991..9bfc32a 100644
--- a/src/H5AC.c
+++ b/src/H5AC.c
@@ -499,6 +499,7 @@ static const char * H5AC_entry_type_names[H5AC_NTYPES] =
     "fixed array headers",
     "fixed array data block",
     "fixed array data block pages",
+    "superblock",
     "test entry"	/* for testing only -- not used for actual files */
 };
 
diff --git a/src/H5ACprivate.h b/src/H5ACprivate.h
index 17ee012..99231ca 100644
--- a/src/H5ACprivate.h
+++ b/src/H5ACprivate.h
@@ -70,6 +70,7 @@ typedef enum {
     H5AC_FARRAY_HDR_ID,	/*fixed array header		     	     */
     H5AC_FARRAY_DBLOCK_ID, /*fixed array data block	     	     */
     H5AC_FARRAY_DBLK_PAGE_ID, /*fixed array data block page          */
+    H5AC_SUPERBLOCK_ID, /* file superblock                           */
     H5AC_TEST_ID,	/*test entry -- not used for actual files    */
     H5AC_NTYPES		/* Number of types, must be last             */
 } H5AC_type_t;
diff --git a/src/H5Cpkg.h b/src/H5Cpkg.h
index 08a903a..4bc105d 100644
--- a/src/H5Cpkg.h
+++ b/src/H5Cpkg.h
@@ -857,7 +857,7 @@
  ****************************************************************************/
 
 #define H5C__H5C_T_MAGIC	0x005CAC0E
-#define H5C__MAX_NUM_TYPE_IDS	24
+#define H5C__MAX_NUM_TYPE_IDS	25
 #define H5C__PREFIX_LEN		32
 
 struct H5C_t
diff --git a/src/H5F.c b/src/H5F.c
index 1cb8cdf..85ad71d 100644
--- a/src/H5F.c
+++ b/src/H5F.c
@@ -861,23 +861,20 @@ H5F_new(H5F_file_t *shared, hid_t fcpl_id, hid_t fapl_id, H5FD_t *lf)
 	f->shared = shared;
     } /* end if */
     else {
-        unsigned super_vers = HDF5_SUPERBLOCK_VERSION_DEF;      /* Superblock version for file */
         H5P_genplist_t *plist;          /* Property list */
         size_t u;                       /* Local index variable */
 
         HDassert(lf != NULL);
         if(NULL == (f->shared = H5FL_CALLOC(H5F_file_t)))
             HGOTO_ERROR(H5E_FILE, H5E_NOSPACE, NULL, "can't allocate shared file structure")
-	f->shared->base_addr = HADDR_UNDEF;
-	f->shared->extension_addr = HADDR_UNDEF;
+
+        f->shared->super_addr = HADDR_UNDEF;
 	f->shared->sohm_addr = HADDR_UNDEF;
 	f->shared->sohm_vers = HDF5_SHAREDHEADER_VERSION;
         for(u = 0; u < NELMTS(f->shared->fs_addr); u++)
             f->shared->fs_addr[u] = HADDR_UNDEF;
-	f->shared->driver_addr = HADDR_UNDEF;
 	f->shared->accum.loc = HADDR_UNDEF;
         f->shared->lf = lf;
-        f->shared->root_addr = HADDR_UNDEF;
 
 	/*
 	 * Copy the file creation and file access property lists into the
@@ -893,10 +890,6 @@ H5F_new(H5F_file_t *shared, hid_t fcpl_id, hid_t fapl_id, H5FD_t *lf)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get byte number for address")
         if(H5P_get(plist, H5F_CRT_OBJ_BYTE_NUM_NAME, &f->shared->sizeof_size) < 0)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get byte number for object size")
-        if(H5P_get(plist, H5F_CRT_SYM_LEAF_NAME, &f->shared->sym_leaf_k) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get byte number for object size")
-        if(H5P_get(plist, H5F_CRT_BTREE_RANK_NAME, &f->shared->btree_k[0]) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "unable to get rank for btree internal nodes")
         if(H5P_get(plist, H5F_CRT_SHMSG_NINDEXES_NAME, &f->shared->sohm_nindexes)<0)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get number of SOHM indexes")
         HDassert(f->shared->sohm_nindexes < 255);
@@ -951,29 +944,6 @@ H5F_new(H5F_file_t *shared, hid_t fcpl_id, hid_t fapl_id, H5FD_t *lf)
          */
         f->shared->use_tmp_space = !(IS_H5FD_MPI(f));
 
-        /* Bump superblock version if we are to use the latest version of the format */
-        if(f->shared->latest_format)
-            super_vers = HDF5_SUPERBLOCK_VERSION_LATEST;
-        /* Bump superblock version to create superblock extension for SOHM info */
-        else if(f->shared->sohm_nindexes > 0)
-            super_vers = HDF5_SUPERBLOCK_VERSION_2;
-        /* Check for non-default indexed storage B-tree internal 'K' value
-         * and set the version # of the superblock to 1 if it is a non-default
-         * value.
-         */
-        else if(f->shared->btree_k[H5B_CHUNK_ID] != HDF5_BTREE_CHUNK_IK_DEF)
-            super_vers = HDF5_SUPERBLOCK_VERSION_1;
-
-        /* If a newer superblock version is required, set it here */
-        if(super_vers != HDF5_SUPERBLOCK_VERSION_DEF) {
-            H5P_genplist_t *c_plist;              /* Property list */
-
-            if(NULL == (c_plist = (H5P_genplist_t *)H5I_object(f->shared->fcpl_id)))
-                HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not property list")
-            if(H5P_set(c_plist, H5F_CRT_SUPER_VERS_NAME, &super_vers) < 0)
-                HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "unable to set superblock version")
-        } /* end if */
-
 	/*
 	 * Create a metadata cache with the specified number of elements.
 	 * The cache might be created with a different number of elements and
@@ -1050,8 +1020,20 @@ H5F_dest(H5F_t *f, hid_t dxpl_id)
             H5AC_stats(f);
 #endif /* H5AC_DUMP_STATS_ON_CLOSE */
 
-            /* Flush and invalidate all caches */
-            if(H5F_flush(f, dxpl_id, H5F_SCOPE_LOCAL, H5F_FLUSH_INVALIDATE | H5F_FLUSH_CLOSING) < 0)
+            /* Flush all caches and indicate we are closing the file */
+            if(H5F_flush(f, dxpl_id, H5F_SCOPE_LOCAL, H5F_FLUSH_CLOSING) < 0)
+                /* Push error, but keep going*/
+                HDONE_ERROR(H5E_CACHE, H5E_CANTFLUSH, FAIL, "unable to flush cache")
+
+            /* Unpin the superblock, since we're about to destroy the cache */
+            if(H5AC_unpin_entry(f, f->shared->sblock) < 0)
+                /* Push error, but keep going*/
+                HDONE_ERROR(H5E_FSPACE, H5E_CANTUNPIN, FAIL, "unable to unpin superblock")
+            f->shared->sblock = NULL;
+
+            /* Flush all caches and indicate all cached objects should be invalidated */
+            /* (The caches should already be clean and we should just be invalidating objects) */
+            if(H5F_flush(f, dxpl_id, H5F_SCOPE_LOCAL, H5F_FLUSH_INVALIDATE) < 0)
                 /* Push error, but keep going*/
                 HDONE_ERROR(H5E_CACHE, H5E_CANTFLUSH, FAIL, "unable to flush cache")
         } /* end if */
@@ -1110,9 +1092,6 @@ H5F_dest(H5F_t *f, hid_t dxpl_id)
         f->shared->mtab.child = (H5F_mount_t *)H5MM_xfree(f->shared->mtab.child);
         f->shared->mtab.nalloc = 0;
 
-        /* Free root group symbol table entry, if any */
-        f->shared->root_ent = (H5G_entry_t *)H5MM_xfree(f->shared->root_ent);
-
         /* Destroy shared file struct */
         f->shared = (H5F_file_t *)H5FL_FREE(H5F_file_t, f->shared);
 
@@ -1293,22 +1272,6 @@ H5F_open(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id, hid_t d
     file->intent = flags;
     file->name = H5MM_xstrdup(name);
 
-    /* Get the file access property list, for future queries */
-    if(NULL == (a_plist = (H5P_genplist_t *)H5I_object(fapl_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not file access property list")
-
-    /* This step is for h5repart tool only. If user wants to change file driver from
-     * family to sec2 while using h5repart, this private property should be set so that
-     * in the later step, the library can ignore the family driver information saved
-     * in the superblock.
-     */
-    if(H5P_exist_plist(a_plist, H5F_ACS_FAMILY_TO_SEC2_NAME) > 0) {
-        if(H5P_get(a_plist, H5F_ACS_FAMILY_TO_SEC2_NAME, &shared->fam_to_sec2) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get property of changing family to sec2")
-    } /* end if */
-    else
-        shared->fam_to_sec2 = FALSE;
-
     /*
      * Read or write the file superblock, depending on whether the file is
      * empty or not.
@@ -1330,13 +1293,6 @@ H5F_open(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id, hid_t d
          */
         if(H5G_mkroot(file, dxpl_id, TRUE) < 0)
             HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, NULL, "unable to create/open root group")
-
-        /* Write the superblock to the file */
-        /* (This must be after the root group is created, since the root
-         *      group's symbol table entry is part of the superblock)
-         */
-        if(H5F_super_write(file, dxpl_id) < 0)
-            HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, NULL, "unable to write file superblock")
     } else if (1 == shared->nrefs) {
 	/* Read the superblock if it hasn't been read before. */
         if(H5F_super_read(file, dxpl_id) < 0)
@@ -1347,6 +1303,10 @@ H5F_open(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id, hid_t d
 	    HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "unable to read root group")
     } /* end if */
 
+    /* Get the file access property list, for future queries */
+    if(NULL == (a_plist = (H5P_genplist_t *)H5I_object(fapl_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not file access property list")
+
     /*
      * Decide the file close degree.  If it's the first time to open the
      * file, set the degree to access property list value; if it's the
@@ -1722,13 +1682,6 @@ H5F_flush(H5F_t *f, hid_t dxpl_id, H5F_scope_t scope, unsigned flags)
     if(H5FD_truncate(f->shared->lf, dxpl_id, (unsigned)((flags & H5F_FLUSH_CLOSING) > 0)) < 0)
         HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "low level truncate failed")
 
-    /* Write the superblock to disk */
-    /* (needs to happen before metadata flush (H5AC_flush), since the information
-     *  in the superblock extension may be updated - 2008/10/14, QAK)
-     */
-    if(H5F_super_write(f, dxpl_id) < 0)
-        HGOTO_ERROR(H5E_CACHE, H5E_WRITEERROR, FAIL, "unable to write superblock to file")
-
     /* Flush (and invalidate, if requested) the entire metadata cache */
     H5AC_flags = 0;
     if((flags & H5F_FLUSH_INVALIDATE) != 0 )
diff --git a/src/H5FD.c b/src/H5FD.c
index aaa866b..967017f 100644
--- a/src/H5FD.c
+++ b/src/H5FD.c
@@ -555,7 +555,6 @@ done:
  * Purpose:	Decodes the driver information block.
  *
  * Return:	Success:	Non-negative
- *
  *		Failure:	Negative
  *
  * Programmer:	Robb Matzke
@@ -566,18 +565,17 @@ done:
 herr_t
 H5FD_sb_decode(H5FD_t *file, const char *name, const uint8_t *buf)
 {
-    herr_t      ret_value=SUCCEED;       /* Return value */
+    herr_t      ret_value = SUCCEED;    /* Return value */
 
     FUNC_ENTER_NOAPI(H5FD_sb_decode, FAIL)
 
-    assert(file && file->cls);
-    if(file->cls->sb_decode &&
-            (file->cls->sb_decode)(file, name, buf) < 0)
+    HDassert(file && file->cls);
+    if(file->cls->sb_decode && (file->cls->sb_decode)(file, name, buf) < 0)
 	HGOTO_ERROR(H5E_VFL, H5E_CANTINIT, FAIL, "driver sb_decode request failed")
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-}
+} /* end H5FD_sb_decode() */
 
 
 /*-------------------------------------------------------------------------
@@ -1407,10 +1405,6 @@ done:
  * Programmer:	Robb Matzke
  *              Tuesday, July 27, 1999
  *
- * Modifications:
- *	Vailin Choi, 29th July 2008
- *	  Two more parameters were added to H5FD_alloc() for handling alignment
- *
  *-------------------------------------------------------------------------
  */
 haddr_t
@@ -1435,7 +1429,7 @@ H5FDalloc(H5FD_t *file, H5FD_mem_t type, hid_t dxpl_id, hsize_t size)
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, HADDR_UNDEF, "not a data transfer property list")
 
     /* Do the real work */
-    if(HADDR_UNDEF == (ret_value = H5FD_alloc(file, dxpl_id, type, size, NULL, NULL)))
+    if(HADDR_UNDEF == (ret_value = H5FD_alloc_real(file, dxpl_id, type, size, NULL, NULL)))
 	HGOTO_ERROR(H5E_VFL, H5E_CANTINIT, HADDR_UNDEF, "unable to allocate file memory")
 
     /* (Note compensating for base address subtraction in internal routine) */
@@ -1488,7 +1482,7 @@ H5FDfree(H5FD_t *file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr, hsize_t siz
 
     /* Do the real work */
     /* (Note compensating for base address addition in internal routine) */
-    if(H5FD_free(file, dxpl_id, type, addr - file->base_addr, size) < 0)
+    if(H5FD_free_real(file, dxpl_id, type, addr - file->base_addr, size) < 0)
         HGOTO_ERROR(H5E_VFL, H5E_CANTFREE, FAIL, "file deallocation request failed")
 
 done:
diff --git a/src/H5FDfamily.c b/src/H5FDfamily.c
index e259a4e..9817270 100644
--- a/src/H5FDfamily.c
+++ b/src/H5FDfamily.c
@@ -61,14 +61,19 @@ typedef struct H5FD_family_t {
     hid_t	memb_fapl_id;	/*file access property list for members	*/
     hsize_t	memb_size;	/*actual size of each member file	*/
     hsize_t	pmem_size;	/*member size passed in from property	*/
-    hsize_t	mem_newsize;	/*new member size passed in as private
-                                 *property. It's used only by h5repart  */
     unsigned	nmembs;		/*number of family members		*/
     unsigned	amembs;		/*number of member slots allocated	*/
     H5FD_t	**memb;		/*dynamic array of member pointers	*/
     haddr_t	eoa;		/*end of allocated addresses		*/
     char	*name;		/*name generator printf format		*/
     unsigned	flags;		/*flags for opening additional members	*/
+
+    /* Information from properties set by 'h5repart' tool */
+    hsize_t	mem_newsize;	/*new member size passed in as private
+                                 * property. It's used only by h5repart */
+    hbool_t     repart_members; /* Whether to mark the superblock dirty
+                                 * when it is loaded, so that the family
+                                 * member sizes can be re-encoded       */
 } H5FD_family_t;
 
 /* Driver-specific file access properties */
@@ -741,9 +746,7 @@ H5FD_family_open(const char *name, unsigned flags, hid_t fapl_id,
     H5FD_t     		*ret_value=NULL;
     char		memb_name[4096], temp[4096];
     hsize_t		eof=HADDR_UNDEF;
-    hsize_t             fam_newsize = 0;
     unsigned		t_flags = flags & ~H5F_ACC_CREAT;
-    H5P_genplist_t      *plist;      /* Property list pointer */
 
     FUNC_ENTER_NOAPI(H5FD_family_open, NULL)
 
@@ -765,6 +768,7 @@ H5FD_family_open(const char *name, unsigned flags, hid_t fapl_id,
         file->mem_newsize = 0;            /*New member size used by h5repart only       */
     } /* end if */
     else {
+        H5P_genplist_t      *plist;      /* Property list pointer */
         H5FD_family_fapl_t *fa;
 
         if(NULL == (plist = (H5P_genplist_t *)H5I_object(fapl_id)))
@@ -772,11 +776,19 @@ H5FD_family_open(const char *name, unsigned flags, hid_t fapl_id,
         fa = (H5FD_family_fapl_t *)H5P_get_driver_info(plist);
         HDassert(fa);
 
-        /* New family file size. It's used by h5repart only. */
-        if(H5P_exist_plist(plist, H5F_ACS_FAMILY_NEWSIZE_NAME) > 0)
+        /* Check for new family file size. It's used by h5repart only. */
+        if(H5P_exist_plist(plist, H5F_ACS_FAMILY_NEWSIZE_NAME) > 0) {
+            hsize_t fam_newsize = 0;        /* New member size, when repartitioning */
+
+            /* Get the new family file size */
             if(H5P_get(plist, H5F_ACS_FAMILY_NEWSIZE_NAME, &fam_newsize) < 0)
                 HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get new family member size")
 
+            /* Store information for later */
+            file->mem_newsize = fam_newsize; /* New member size passed in through property */
+            file->repart_members = TRUE;
+        } /* end if */
+
         if(fa->memb_fapl_id==H5P_FILE_ACCESS_DEFAULT) {
             if(H5I_inc_ref(fa->memb_fapl_id, FALSE)<0)
                 HGOTO_ERROR(H5E_VFL, H5E_CANTINC, NULL, "unable to increment ref count on VFL driver")
@@ -789,7 +801,6 @@ H5FD_family_open(const char *name, unsigned flags, hid_t fapl_id,
         } /* end else */
         file->memb_size = fa->memb_size; /* Actual member size to be updated later */
         file->pmem_size = fa->memb_size; /* Member size passed in through property */
-        file->mem_newsize = fam_newsize; /* New member size passed in through property */
     } /* end else */
     file->name = H5MM_strdup(name);
     file->flags = flags;
@@ -797,8 +808,7 @@ H5FD_family_open(const char *name, unsigned flags, hid_t fapl_id,
     /* Check that names are unique */
     sprintf(memb_name, name, 0);
     sprintf(temp, name, 1);
-
-    if (!strcmp(memb_name, temp))
+    if(!HDstrcmp(memb_name, temp))
         HGOTO_ERROR(H5E_FILE, H5E_FILEEXISTS, NULL, "file names not unique")
 
     /* Open all the family members */
@@ -968,23 +978,20 @@ done:
  *              (listed in H5FDpublic.h)
  *
  * Return:	Success:	non-negative
- *
  *		Failure:	negative
  *
  * Programmer:	Quincey Koziol
  *              Friday, August 25, 2000
  *
- * Modifications:
- *
  *-------------------------------------------------------------------------
  */
 /* ARGSUSED */
 static herr_t
-H5FD_family_query(const H5FD_t UNUSED * _f, unsigned long *flags /* out */)
+H5FD_family_query(const H5FD_t * _file, unsigned long *flags /* out */)
 {
-    herr_t ret_value = SUCCEED;
+    const H5FD_family_t	*file = (const H5FD_family_t*)_file;    /* Family VFD info */
 
-    FUNC_ENTER_NOAPI(H5FD_family_query, FAIL)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5FD_family_query)
 
     /* Set the VFL feature flags that this driver supports */
     if(flags) {
@@ -993,10 +1000,13 @@ H5FD_family_query(const H5FD_t UNUSED * _f, unsigned long *flags /* out */)
         *flags |= H5FD_FEAT_ACCUMULATE_METADATA; /* OK to accumulate metadata for faster writes. */
         *flags |= H5FD_FEAT_DATA_SIEVE;       /* OK to perform data sieving for faster raw data reads & writes */
         *flags |= H5FD_FEAT_AGGREGATE_SMALLDATA; /* OK to aggregate "small" raw data allocations */
+
+        /* Check for flags that are set by h5repart */
+        if(file->repart_members)
+            *flags |= H5FD_FEAT_DIRTY_SBLK_LOAD; /* Mark the superblock dirty when it is loaded (so the family member sizes are rewritten) */
     } /* end if */
 
-done:
-    FUNC_LEAVE_NOAPI(ret_value)
+    FUNC_LEAVE_NOAPI(SUCCEED)
 } /* end H5FD_family_query() */
 
 
diff --git a/src/H5FDmulti.c b/src/H5FDmulti.c
index e0421a7..328b530 100644
--- a/src/H5FDmulti.c
+++ b/src/H5FDmulti.c
@@ -837,8 +837,6 @@ H5FD_multi_sb_encode(H5FD_t *_file, char *name/*out*/,
  * Programmer:	Robb Matzke
  *              Monday, August 16, 1999
  *
- * Modifications:
- *
  *-------------------------------------------------------------------------
  */
 static herr_t
diff --git a/src/H5FDpkg.h b/src/H5FDpkg.h
index 9401b52..7c0988e 100644
--- a/src/H5FDpkg.h
+++ b/src/H5FDpkg.h
@@ -53,6 +53,10 @@
 /* Package Private Prototypes */
 /******************************/
 H5_DLL herr_t H5FD_init(void);
+H5_DLL haddr_t H5FD_alloc_real(H5FD_t *file, hid_t dxpl_id, H5FD_mem_t type,
+    hsize_t size, haddr_t *align_addr, hsize_t *align_size);
+H5_DLL herr_t H5FD_free_real(H5FD_t *file, hid_t dxpl_id, H5FD_mem_t type,
+    haddr_t addr, hsize_t size);
 
 
 /* Testing routines */
diff --git a/src/H5FDprivate.h b/src/H5FDprivate.h
index 25b2f24..6b2e4fe 100644
--- a/src/H5FDprivate.h
+++ b/src/H5FDprivate.h
@@ -35,6 +35,7 @@
 
 /* Forward declarations for prototype arguments */
 struct H5P_genplist_t;
+struct H5F_t;
 
 /* Prototypes */
 H5_DLL int H5FD_term_interface(void);
@@ -55,10 +56,12 @@ H5_DLL H5FD_t *H5FD_open(const char *name, unsigned flags, hid_t fapl_id,
 H5_DLL herr_t H5FD_close(H5FD_t *file);
 H5_DLL int H5FD_cmp(const H5FD_t *f1, const H5FD_t *f2);
 H5_DLL int H5FD_query(const H5FD_t *f, unsigned long *flags/*out*/);
-H5_DLL haddr_t H5FD_alloc(H5FD_t *file, hid_t dxpl_id, H5FD_mem_t type, hsize_t size, haddr_t *align_addr, hsize_t *align_size);
-H5_DLL herr_t H5FD_free(H5FD_t *file, hid_t dxpl_id, H5FD_mem_t type, haddr_t addr, hsize_t size);
-H5_DLL htri_t H5FD_try_extend(H5FD_t *file, H5FD_mem_t type, haddr_t blk_end,
-    hsize_t extra_requested);
+H5_DLL haddr_t H5FD_alloc(H5FD_t *file, hid_t dxpl_id, H5FD_mem_t type, struct H5F_t *f,
+    hsize_t size, haddr_t *align_addr, hsize_t *align_size);
+H5_DLL herr_t H5FD_free(H5FD_t *file, hid_t dxpl_id, H5FD_mem_t type, struct H5F_t *f,
+    haddr_t addr, hsize_t size);
+H5_DLL htri_t H5FD_try_extend(H5FD_t *file, H5FD_mem_t type, struct H5F_t *f,
+    haddr_t blk_end, hsize_t extra_requested);
 H5_DLL haddr_t H5FD_get_eoa(const H5FD_t *file, H5FD_mem_t type);
 H5_DLL herr_t H5FD_set_eoa(H5FD_t *file, H5FD_mem_t type, haddr_t addr);
 H5_DLL haddr_t H5FD_get_eof(const H5FD_t *file);
diff --git a/src/H5FDpublic.h b/src/H5FDpublic.h
index fde8556..ed24506 100644
--- a/src/H5FDpublic.h
+++ b/src/H5FDpublic.h
@@ -190,6 +190,20 @@ typedef enum H5F_mem_t	H5FD_mem_t;
      * and then sub-allocate "small" raw data requests from that larger block.
      */
 #define H5FD_FEAT_AGGREGATE_SMALLDATA   0x00000010
+    /*
+     * Defining the H5FD_FEAT_IGNORE_DRVRINFO for a VFL driver means that
+     * the library will ignore the driver info that is encoded in the file
+     * for the VFL driver.  (This will cause the driver info to be eliminated
+     * from the file when it is flushed/closed, if the file is opened R/W).
+     */
+#define H5FD_FEAT_IGNORE_DRVRINFO       0x00000020
+    /*
+     * Defining the H5FD_FEAT_DIRTY_SBLK_LOAD for a VFL driver means that
+     * the library will mark the superblock dirty when the file is opened
+     * R/W.  This will cause the driver info to be re-encoded when the file
+     * is flushed/closed.
+     */
+#define H5FD_FEAT_DIRTY_SBLK_LOAD       0x00000040
 
 
 /* Forward declaration */
diff --git a/src/H5FDsec2.c b/src/H5FDsec2.c
index 35ade20..0b4632d 100644
--- a/src/H5FDsec2.c
+++ b/src/H5FDsec2.c
@@ -90,6 +90,10 @@ typedef struct H5FD_sec2_t {
     DWORD fileindexlo;
     DWORD fileindexhi;
 #endif
+
+    /* Information from properties set by 'h5repart' tool */
+    hbool_t     fam_to_sec2;    /* Whether to eliminate the family driver info
+                                 * and convert this file to a single file */
 } H5FD_sec2_t;
 
 
@@ -325,8 +329,7 @@ done:
  */
 /* ARGSUSED */
 static H5FD_t *
-H5FD_sec2_open(const char *name, unsigned flags, hid_t UNUSED fapl_id,
-	       haddr_t maxaddr)
+H5FD_sec2_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t maxaddr)
 {
     int	o_flags;
     int		fd=(-1);
@@ -388,8 +391,26 @@ H5FD_sec2_open(const char *name, unsigned flags, hid_t UNUSED fapl_id,
 
 #endif
 
+    /* Check for non-default FAPL */
+    if(H5P_FILE_ACCESS_DEFAULT != fapl_id) {
+        H5P_genplist_t      *plist;      /* Property list pointer */
+
+        /* Get the FAPL */
+        if(NULL == (plist = (H5P_genplist_t *)H5I_object(fapl_id)))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list")
+
+        /* This step is for h5repart tool only. If user wants to change file driver from
+         * family to sec2 while using h5repart, this private property should be set so that
+         * in the later step, the library can ignore the family driver information saved
+         * in the superblock.
+         */
+        if(H5P_exist_plist(plist, H5F_ACS_FAMILY_TO_SEC2_NAME) > 0)
+            if(H5P_get(plist, H5F_ACS_FAMILY_TO_SEC2_NAME, &file->fam_to_sec2) < 0)
+                HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get property of changing family to sec2")
+    } /* end if */
+
     /* Set return value */
-    ret_value=(H5FD_t*)file;
+    ret_value = (H5FD_t*)file;
 
 done:
     if(ret_value==NULL) {
@@ -398,7 +419,7 @@ done:
     } /* end if */
 
     FUNC_LEAVE_NOAPI(ret_value)
-}
+} /* end H5FD_sec2_open() */
 
 
 /*-------------------------------------------------------------------------
@@ -516,11 +537,11 @@ done:
  */
 /* ARGSUSED */
 static herr_t
-H5FD_sec2_query(const H5FD_t UNUSED * _f, unsigned long *flags /* out */)
+H5FD_sec2_query(const H5FD_t *_file, unsigned long *flags /* out */)
 {
-    herr_t ret_value = SUCCEED;         /* Return value */
+    const H5FD_sec2_t	*file = (const H5FD_sec2_t*)_file;    /* sec2 VFD info */
 
-    FUNC_ENTER_NOAPI(H5FD_sec2_query, FAIL)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5FD_sec2_query)
 
     /* Set the VFL feature flags that this driver supports */
     if(flags) {
@@ -529,10 +550,13 @@ H5FD_sec2_query(const H5FD_t UNUSED * _f, unsigned long *flags /* out */)
         *flags |= H5FD_FEAT_ACCUMULATE_METADATA; /* OK to accumulate metadata for faster writes */
         *flags |= H5FD_FEAT_DATA_SIEVE;       /* OK to perform data sieving for faster raw data reads & writes */
         *flags |= H5FD_FEAT_AGGREGATE_SMALLDATA; /* OK to aggregate "small" raw data allocations */
+
+        /* Check for flags that are set by h5repart */
+        if(file->fam_to_sec2)
+            *flags |= H5FD_FEAT_IGNORE_DRVRINFO; /* Ignore the driver info when file is opened (which eliminates it) */
     } /* end if */
 
-done:
-    FUNC_LEAVE_NOAPI(ret_value)
+    FUNC_LEAVE_NOAPI(SUCCEED)
 } /* end H5FD_sec2_query() */
 
 
diff --git a/src/H5FDspace.c b/src/H5FDspace.c
index 0fadc1e..5526b03 100644
--- a/src/H5FDspace.c
+++ b/src/H5FDspace.c
@@ -42,7 +42,6 @@
 #include "H5Fprivate.h"         /* File access				*/
 #include "H5FDpkg.h"		/* File Drivers				*/
 #include "H5FDmulti.h"		/* Usage-partitioned file family	*/
-#include "H5MMprivate.h"	/* Memory management			*/
 
 
 /****************/
@@ -122,10 +121,6 @@ H5FD_space_init_interface(void)
  * Programmer:  Bill Wendling
  *              Wednesday, 04. December, 2002
  *
- * Modifications:
- *	Vailin Choi, 29th July 2008
- *	  Add 2 more parameters for handling alignment: address and size of the fragment
- *
  *-------------------------------------------------------------------------
  */
 static haddr_t
@@ -180,9 +175,9 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5FD_alloc
+ * Function:    H5FD_alloc_real
  *
- * Purpose:     Private version of H5FDalloc().
+ * Purpose:     Allocate space in the file with the VFD
  *
  * Return:      Success:    The format address of the new file memory.
  *              Failure:    The undefined address HADDR_UNDEF
@@ -190,18 +185,14 @@ done:
  * Programmer:  Robb Matzke
  *              Wednesday, August  4, 1999
  *
- * Modification:
- *	Vailin Choi, 29th July 2008
- *	  Add two more parameters () for handling alignment: address & size of the fragment
- *
  *-------------------------------------------------------------------------
  */
 haddr_t
-H5FD_alloc(H5FD_t *file, hid_t dxpl_id, H5FD_mem_t type, hsize_t size, haddr_t *frag_addr, hsize_t *frag_size)
+H5FD_alloc_real(H5FD_t *file, hid_t dxpl_id, H5FD_mem_t type, hsize_t size, haddr_t *frag_addr, hsize_t *frag_size)
 {
-    haddr_t     ret_value = HADDR_UNDEF;
+    haddr_t     ret_value;              /* Return value */
 
-    FUNC_ENTER_NOAPI(H5FD_alloc, HADDR_UNDEF)
+    FUNC_ENTER_NOAPI(H5FD_alloc_real, HADDR_UNDEF)
 #ifdef H5FD_ALLOC_DEBUG
 HDfprintf(stderr, "%s: type = %u, size = %Hu\n", FUNC, (unsigned)type, size);
 #endif /* H5FD_ALLOC_DEBUG */
@@ -230,13 +221,59 @@ done:
 HDfprintf(stderr, "%s: ret_value = %a\n", FUNC, ret_value);
 #endif /* H5FD_ALLOC_DEBUG */
     FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5FD_alloc_real() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_alloc
+ *
+ * Purpose:     Wrapper for H5FD_alloc, to make certain EOA changes are
+ *		reflected in superblock.
+ *
+ * Note:	When the metadata cache routines are updated to allow
+ *		marking an entry dirty without a H5F_t*, this routine should
+ *		be changed to take a H5F_super_t* directly.
+ *
+ * Return:      Success:    The format address of the new file memory.
+ *              Failure:    The undefined address HADDR_UNDEF
+ *
+ * Programmer:  Quincey Koziol
+ *              Friday, August 14, 2009
+ *
+ *-------------------------------------------------------------------------
+ */
+haddr_t
+H5FD_alloc(H5FD_t *file, hid_t dxpl_id, H5FD_mem_t type, H5F_t *f, hsize_t size,
+    haddr_t *frag_addr, hsize_t *frag_size)
+{
+    haddr_t     ret_value;              /* Return value */
+
+    FUNC_ENTER_NOAPI(H5FD_alloc, HADDR_UNDEF)
+
+    /* check args */
+    HDassert(file);
+    HDassert(file->cls);
+    HDassert(type >= H5FD_MEM_DEFAULT && type < H5FD_MEM_NTYPES);
+    HDassert(size > 0);
+
+    /* Call the real 'alloc' routine */
+    ret_value = H5FD_alloc_real(file, dxpl_id, type, size, frag_addr, frag_size);
+    if(!H5F_addr_defined(ret_value))
+        HGOTO_ERROR(H5E_VFL, H5E_CANTALLOC, HADDR_UNDEF, "real 'alloc' request failed")
+
+    /* Mark superblock dirty in cache, so change to EOA will get encoded */
+    if(H5F_super_dirty(f) < 0)
+        HGOTO_ERROR(H5E_VFL, H5E_CANTMARKDIRTY, HADDR_UNDEF, "unable to mark superblock as dirty")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5FD_alloc() */
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5FD_free
+ * Function:    H5FD_free_real
  *
- * Purpose:     Private version of H5FDfree()
+ * Purpose:     Release space back to the VFD
  *
  * Return:      Success:        Non-negative
  *              Failure:        Negative
@@ -247,11 +284,11 @@ HDfprintf(stderr, "%s: ret_value = %a\n", FUNC, ret_value);
  *-------------------------------------------------------------------------
  */
 herr_t
-H5FD_free(H5FD_t *file, hid_t dxpl_id, H5FD_mem_t type, haddr_t addr, hsize_t size)
+H5FD_free_real(H5FD_t *file, hid_t dxpl_id, H5FD_mem_t type, haddr_t addr, hsize_t size)
 {
     herr_t      ret_value = SUCCEED;       /* Return value */
 
-    FUNC_ENTER_NOAPI(H5FD_free, FAIL)
+    FUNC_ENTER_NOAPI_NOINIT(H5FD_free_real)
 
     /* Check args */
     HDassert(file);
@@ -265,14 +302,14 @@ HDfprintf(stderr, "%s: type = %u, addr = %a, size = %Hu\n", FUNC, (unsigned)type
 
     /* Sanity checking */
     if(!H5F_addr_defined(addr))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid file offset")
+        HGOTO_ERROR(H5E_VFL, H5E_BADVALUE, FAIL, "invalid file offset")
 
     /* Convert address to absolute file offset */
     addr += file->base_addr;
 
     /* More sanity checking */
     if(addr > file->maxaddr || H5F_addr_overflow(addr, size) || (addr + size) > file->maxaddr)
-        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid file free space region to free")
+        HGOTO_ERROR(H5E_VFL, H5E_BADVALUE, FAIL, "invalid file free space region to free")
 
     /* Check for file driver 'free' callback and call it if available */
     if(file->cls->free) {
@@ -309,6 +346,51 @@ HDfprintf(stderr, "%s: LEAKED MEMORY!!! type = %u, addr = %a, size = %Hu\n", FUN
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5FD_free_real() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_free
+ *
+ * Purpose:     Wrapper for H5FD_free_real, to make certain EOA changes are
+ *		reflected in superblock.
+ *
+ * Note:	When the metadata cache routines are updated to allow
+ *		marking an entry dirty without a H5F_t*, this routine should
+ *		be changed to take a H5F_super_t* directly.
+ *
+ * Return:      Success:        Non-negative
+ *              Failure:        Negative
+ *
+ * Programmer:  Quincey Koziol
+ *              Friday, August 14, 2009
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5FD_free(H5FD_t *file, hid_t dxpl_id, H5FD_mem_t type, H5F_t *f, haddr_t addr,
+    hsize_t size)
+{
+    herr_t      ret_value = SUCCEED;       /* Return value */
+
+    FUNC_ENTER_NOAPI(H5FD_free, FAIL)
+
+    /* Check args */
+    HDassert(file);
+    HDassert(file->cls);
+    HDassert(type >= H5FD_MEM_DEFAULT && type < H5FD_MEM_NTYPES);
+    HDassert(size > 0);
+
+    /* Call the real 'free' routine */
+    if(H5FD_free_real(file, dxpl_id, type, addr, size) < 0)
+        HGOTO_ERROR(H5E_VFL, H5E_CANTFREE, FAIL, "real 'free' request failed")
+
+    /* Mark superblock dirty in cache, so change to EOA will get encoded */
+    if(H5F_super_dirty(f) < 0)
+        HGOTO_ERROR(H5E_VFL, H5E_CANTMARKDIRTY, FAIL, "unable to mark superblock as dirty")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5FD_free() */
 
 
@@ -317,6 +399,10 @@ done:
  *
  * Purpose:	Extend a block at the end of the file, if possible.
  *
+ * Note:	When the metadata cache routines are updated to allow
+ *		marking an entry dirty without a H5F_t*, this routine should
+ *		be changed to take a H5F_super_t* directly.
+ *
  * Return:	Success:	TRUE(1)  - Block was extended
  *                              FALSE(0) - Block could not be extended
  * 		Failure:	FAIL
@@ -324,14 +410,11 @@ done:
  * Programmer:  Quincey Koziol
  *              Thursday, 17. January, 2008
  *
- * Modification:
- *	Vailin Choi, 29th July 2008
- *	  Two more parameters were added to FD_extend() for handling alignment
- *
  *-------------------------------------------------------------------------
  */
 htri_t
-H5FD_try_extend(H5FD_t *file, H5FD_mem_t type, haddr_t blk_end, hsize_t extra_requested)
+H5FD_try_extend(H5FD_t *file, H5FD_mem_t type, H5F_t *f, haddr_t blk_end,
+    hsize_t extra_requested)
 {
     haddr_t eoa;                /* End of allocated space in file */
     htri_t ret_value = FALSE;   /* Return value */
@@ -343,10 +426,11 @@ H5FD_try_extend(H5FD_t *file, H5FD_mem_t type, haddr_t blk_end, hsize_t extra_re
     HDassert(file->cls);
     HDassert(type >= H5FD_MEM_DEFAULT && type < H5FD_MEM_NTYPES);
     HDassert(extra_requested > 0);
+    HDassert(f);
 
     /* Retrieve the end of the address space */
     if(HADDR_UNDEF == (eoa = file->cls->get_eoa(file, type)))
-	HGOTO_ERROR(H5E_RESOURCE, H5E_CANTGET, FAIL, "driver get_eoa request failed")
+	HGOTO_ERROR(H5E_VFL, H5E_CANTGET, FAIL, "driver get_eoa request failed")
 
     /* Adjust block end by base address of the file, to create absolute address */
     blk_end += file->base_addr;
@@ -355,7 +439,11 @@ H5FD_try_extend(H5FD_t *file, H5FD_mem_t type, haddr_t blk_end, hsize_t extra_re
     if(H5F_addr_eq(blk_end, eoa)) {
         /* Extend the object by extending the underlying file */
         if(HADDR_UNDEF == H5FD_extend(file, type, FALSE, extra_requested, NULL, NULL))
-            HGOTO_ERROR(H5E_RESOURCE, H5E_CANTEXTEND, FAIL, "driver extend request failed")
+            HGOTO_ERROR(H5E_VFL, H5E_CANTEXTEND, FAIL, "driver extend request failed")
+
+        /* Mark superblock dirty in cache, so change to EOA will get encoded */
+        if(H5F_super_dirty(f) < 0)
+            HGOTO_ERROR(H5E_VFL, H5E_CANTMARKDIRTY, FAIL, "unable to mark superblock as dirty")
 
         /* Indicate success */
         HGOTO_DONE(TRUE)
diff --git a/src/H5Fdbg.c b/src/H5Fdbg.c
index b570516..5f14357 100644
--- a/src/H5Fdbg.c
+++ b/src/H5Fdbg.c
@@ -51,7 +51,6 @@ H5F_debug(H5F_t *f, FILE *stream, int indent, int fwidth)
 {
     H5P_genplist_t *plist;              /* File creation property list */
     hsize_t userblock_size;             /* Userblock size */
-    unsigned super_vers;                /* Superblock version # */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI(H5F_debug, FAIL)
@@ -61,6 +60,7 @@ H5F_debug(H5F_t *f, FILE *stream, int indent, int fwidth)
     HDassert(stream);
     HDassert(indent >= 0);
     HDassert(fwidth >= 0);
+    HDassert(f->shared->super_addr != HADDR_UNDEF);
 
     /* Get property list */
     if(NULL == (plist = (H5P_genplist_t *)H5I_object(f->shared->fcpl_id)))
@@ -69,8 +69,6 @@ H5F_debug(H5F_t *f, FILE *stream, int indent, int fwidth)
     /* Retrieve file creation properties */
     if(H5P_get(plist, H5F_CRT_USER_BLOCK_NAME, &userblock_size) < 0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get userblock size")
-    if(H5P_get(plist, H5F_CRT_SUPER_VERS_NAME, &super_vers) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get superblock version")
 
     /* debug */
     HDfprintf(stream, "%*sFile Super Block...\n", indent, "");
@@ -82,12 +80,12 @@ H5F_debug(H5F_t *f, FILE *stream, int indent, int fwidth)
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
 	      "File open reference count:", f->shared->nrefs);
     HDfprintf(stream, "%*s%-*s %a (abs)\n", indent, "", fwidth,
-	      "Address of super block:", f->shared->base_addr);
+	      "Address of super block:", f->shared->sblock->base_addr);
     HDfprintf(stream, "%*s%-*s %Hu bytes\n", indent, "", fwidth,
 	      "Size of userblock:", userblock_size);
 
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
-	      "Superblock version number:", super_vers);
+	      "Superblock version number:", f->shared->sblock->super_vers);
 
     /* Hard-wired versions */
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
@@ -102,13 +100,13 @@ H5F_debug(H5F_t *f, FILE *stream, int indent, int fwidth)
     HDfprintf(stream, "%*s%-*s %u bytes\n", indent, "", fwidth,
 	      "Size of file lengths (hsize_t type):", (unsigned) f->shared->sizeof_size);
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
-	      "Symbol table leaf node 1/2 rank:", f->shared->sym_leaf_k);
+	      "Symbol table leaf node 1/2 rank:", f->shared->sblock->sym_leaf_k);
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
-	      "Symbol table internal node 1/2 rank:", f->shared->btree_k[H5B_SNODE_ID]);
+	      "Symbol table internal node 1/2 rank:", f->shared->sblock->btree_k[H5B_SNODE_ID]);
     HDfprintf(stream, "%*s%-*s 0x%02x\n", indent, "", fwidth,
-	      "File status flags:", (unsigned)(f->shared->status_flags));
+	      "File status flags:", (unsigned)(f->shared->sblock->status_flags));
     HDfprintf(stream, "%*s%-*s %a (rel)\n", indent, "", fwidth,
-	      "Superblock extension address:", f->shared->extension_addr);
+	      "Superblock extension address:", f->shared->sblock->ext_addr);
     HDfprintf(stream, "%*s%-*s %a (rel)\n", indent, "", fwidth,
 	      "Shared object header message table address:", f->shared->sohm_addr);
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
@@ -117,14 +115,14 @@ H5F_debug(H5F_t *f, FILE *stream, int indent, int fwidth)
 	      "Number of shared object header message indexes:", (unsigned) f->shared->sohm_nindexes);
 
     HDfprintf(stream, "%*s%-*s %a (rel)\n", indent, "", fwidth,
-	      "Address of driver information block:", f->shared->driver_addr);
+	      "Address of driver information block:", f->shared->sblock->driver_addr);
 
     HDfprintf(stream, "%*s%-*s %s\n", indent, "", fwidth,
 	      "Root group symbol table entry:",
 	      f->shared->root_grp ? "" : "(none)");
     if(f->shared->root_grp) {
-        if(f->shared->root_ent) /* Use real root group symbol table entry */
-            H5G_ent_debug(f, f->shared->root_ent, stream, indent + 3,
+        if(f->shared->sblock->root_ent) /* Use real root group symbol table entry */
+            H5G_ent_debug(f, f->shared->sblock->root_ent, stream, indent + 3,
                 MAX(0, fwidth - 3), NULL);
         else {
             H5O_loc_t *root_oloc;   /* Root object location */
diff --git a/src/H5Fpkg.h b/src/H5Fpkg.h
index c7ac1fa..84bab35 100644
--- a/src/H5Fpkg.h
+++ b/src/H5Fpkg.h
@@ -71,6 +71,58 @@
 /* Macro to abstract checking whether file is using a free space manager */
 #define H5F_HAVE_FREE_SPACE_MANAGER(F)  TRUE    /* Currently always have a free space manager */
 
+/* Macros for encoding/decoding superblock */
+#define H5F_MAX_DRVINFOBLOCK_SIZE  1024         /* Maximum size of superblock driver info buffer */
+#define H5F_DRVINFOBLOCK_HDR_SIZE 16            /* Size of superblock driver info header */
+
+/* Superblock sizes for various versions */
+#define H5F_SIZEOF_CHKSUM 4     /* Checksum size in the file */
+
+/* Fixed-size portion at the beginning of all superblocks */
+#define H5F_SUPERBLOCK_FIXED_SIZE ( H5F_SIGNATURE_LEN                   \
+        + 1) /* superblock version */
+
+/* Macros for computing variable-size superblock size */
+#define H5F_SUPERBLOCK_VARLEN_SIZE_COMMON                               \
+        (2  /* freespace, and root group versions */			\
+        + 1 /* reserved */                                              \
+        + 3 /* shared header vers, size of address, size of lengths */  \
+        + 1 /* reserved */                                              \
+        + 4 /* group leaf k, group internal k */                        \
+        + 4) /* consistency flags */
+#define H5F_SUPERBLOCK_VARLEN_SIZE_V0(f)                                \
+        ( H5F_SUPERBLOCK_VARLEN_SIZE_COMMON /* Common variable-length info */ \
+        + H5F_SIZEOF_ADDR(f) /* base address */                         \
+        + H5F_SIZEOF_ADDR(f) /* <unused> */				\
+        + H5F_SIZEOF_ADDR(f) /* EOF address */                          \
+        + H5F_SIZEOF_ADDR(f) /* driver block address */                 \
+        + H5G_SIZEOF_ENTRY(f)) /* root group ptr */
+#define H5F_SUPERBLOCK_VARLEN_SIZE_V1(f)                                \
+        ( H5F_SUPERBLOCK_VARLEN_SIZE_COMMON /* Common variable-length info */ \
+        + 2 /* indexed B-tree internal k */                             \
+        + 2 /* reserved */                                              \
+        + H5F_SIZEOF_ADDR(f) /* base address */                         \
+        + H5F_SIZEOF_ADDR(f) /* <unused> */				\
+        + H5F_SIZEOF_ADDR(f) /* EOF address */                          \
+        + H5F_SIZEOF_ADDR(f) /* driver block address */                 \
+        + H5G_SIZEOF_ENTRY(f)) /* root group ptr */
+#define H5F_SUPERBLOCK_VARLEN_SIZE_V2(f)                                \
+        ( 2 /* size of address, size of lengths */                      \
+        + 1 /* consistency flags */                                     \
+        + H5F_SIZEOF_ADDR(f) /* base address */                         \
+        + H5F_SIZEOF_ADDR(f) /* superblock extension address */         \
+        + H5F_SIZEOF_ADDR(f) /* EOF address */                          \
+        + H5F_SIZEOF_ADDR(f) /* root group object header address */     \
+        + H5F_SIZEOF_CHKSUM) /* superblock checksum (keep this last) */
+#define H5F_SUPERBLOCK_VARLEN_SIZE(v, f) (				\
+        (v == 0 ? H5F_SUPERBLOCK_VARLEN_SIZE_V0(f) : 0)			\
+        + (v == 1 ? H5F_SUPERBLOCK_VARLEN_SIZE_V1(f) : 0)               \
+        + (v == 2 ? H5F_SUPERBLOCK_VARLEN_SIZE_V2(f) : 0))
+
+/* Total size of superblock, depends on superblock version */
+#define H5F_SUPERBLOCK_SIZE(v, f) ( H5F_SUPERBLOCK_FIXED_SIZE           \
+        + H5F_SUPERBLOCK_VARLEN_SIZE(v, f))
+
 
 /* Structure for metadata & "small [raw] data" block aggregation fields */
 struct H5F_blk_aggr_t {
@@ -113,6 +165,23 @@ typedef struct H5F_mtab_t {
     H5F_mount_t		*child;	/* An array of mount records		*/
 } H5F_mtab_t;
 
+/* Structure specifically to store superblock. This was originally
+ * maintained entirely within H5F_file_t, but is now extracted
+ * here because the superblock is now handled by the cache */
+typedef struct H5F_super_t {
+    H5AC_info_t cache_info;     /* Cache entry information structure          */
+    unsigned    super_vers;     /* Superblock version                         */
+    uint8_t     status_flags;   /* File status flags                          */
+    unsigned    sym_leaf_k;     /* Size of leaves in symbol tables            */
+    unsigned    btree_k[H5B_NUM_BTREE_ID]; /* B-tree key values for each type */
+    haddr_t     base_addr;      /* Absolute base address for rel.addrs.       */
+                                /* (superblock for file is at this offset)    */
+    haddr_t     ext_addr;       /* Relative address of superblock extension   */
+    haddr_t     driver_addr;    /* File driver information block address      */
+    haddr_t     root_addr;      /* Root group address                         */
+    H5G_entry_t *root_ent;      /* Root group symbol table entry              */
+} H5F_super_t;
+
 /*
  * Define the structure to store the file information for HDF5 files. One of
  * these structures is allocated per file, not per H5Fopen(). That is, set of
@@ -122,23 +191,18 @@ typedef struct H5F_mtab_t {
  */
 typedef struct H5F_file_t {
     H5FD_t	*lf; 		/* Lower level file handle for I/O	*/
+    H5F_super_t *sblock;        /* Pointer to (pinned) superblock for file */
+    haddr_t     super_addr;     /* Address of superblock signature      */
     unsigned	nrefs;		/* Ref count for times file is opened	*/
-    uint8_t	status_flags;	/* File status flags			*/
     unsigned	flags;		/* Access Permissions for file          */
     H5F_mtab_t	mtab;		/* File mount table                     */
 
     /* Cached values from FCPL/superblock */
-    unsigned	sym_leaf_k;	/* Size of leaves in symbol tables      */
-    unsigned    btree_k[H5B_NUM_BTREE_ID];  /* B-tree key values for each type  */
     size_t	sizeof_addr;	/* Size of addresses in file            */
     size_t	sizeof_size;	/* Size of offsets in file              */
-    haddr_t	base_addr;	/* Absolute base address for rel.addrs. */
-                                /* (superblock for file is at this offset) */
-    haddr_t	extension_addr;	/* Relative address of superblock extension	*/
     haddr_t	sohm_addr;	/* Relative address of shared object header message table */
     unsigned	sohm_vers;	/* Version of shared message table on disk */
     unsigned	sohm_nindexes;	/* Number of shared messages indexes in the table */
-    haddr_t	driver_addr;	/* File driver information block address*/
     unsigned long feature_flags; /* VFL Driver feature Flags            */
     haddr_t	maxaddr;	/* Maximum address for file             */
 
@@ -159,12 +223,9 @@ typedef struct H5F_file_t {
     unsigned	gc_ref;		/* Garbage-collect references?		*/
     hbool_t	latest_format;	/* Always use the latest format?	*/
     hbool_t	store_msg_crt_idx;  /* Store creation index for object header messages?	*/
-    hbool_t     fam_to_sec2;    /* Is h5repart changing driver from family to sec2? */
     int	ncwfs;			/* Num entries on cwfs list		*/
     struct H5HG_heap_t **cwfs;	/* Global heap cache			*/
     struct H5G_t *root_grp;	/* Open root group			*/
-    H5G_entry_t *root_ent;      /* Root group symbol table entry        */
-    haddr_t     root_addr;      /* Root group address                   */
     H5FO_t *open_objs;          /* Open objects in file                 */
     H5RC_t *grp_btree_shared;   /* Ref-counted group B-tree node info   */
 
@@ -217,6 +278,8 @@ H5FL_EXTERN(H5F_t);
 /* Declare a free list to manage the H5F_file_t struct */
 H5FL_EXTERN(H5F_file_t);
 
+H5_DLLVAR const H5AC_class_t H5AC_SUPERBLOCK[1];
+
 
 /******************************/
 /* Package Private Prototypes */
@@ -233,10 +296,14 @@ H5_DLL herr_t H5F_mount_count_ids(H5F_t *f, unsigned *nopen_files, unsigned *nop
 
 /* Superblock related routines */
 H5_DLL herr_t H5F_super_init(H5F_t *f, hid_t dxpl_id);
-H5_DLL herr_t H5F_super_write(H5F_t *f, hid_t dxpl_id);
 H5_DLL herr_t H5F_super_read(H5F_t *f, hid_t dxpl_id);
 H5_DLL herr_t H5F_super_size(H5F_t *f, hid_t dxpl_id, hsize_t *super_size, hsize_t *super_ext_size);
 
+/* Superblock extension related routines */
+H5_DLL herr_t H5F_super_ext_open(H5F_t *f, haddr_t ext_addr, H5O_loc_t *ext_ptr);
+H5_DLL herr_t H5F_super_ext_write_msg(H5F_t *f, hid_t dxpl_id, void *mesg, unsigned id, hbool_t may_create);
+H5_DLL herr_t H5F_super_ext_close(H5F_t *f, H5O_loc_t *ext_ptr);
+
 /* Metadata accumulator routines */
 H5_DLL htri_t H5F_accum_read(const H5F_t *f, hid_t dxpl_id, H5FD_mem_t type,
     haddr_t addr, size_t size, void *buf);
diff --git a/src/H5Fprivate.h b/src/H5Fprivate.h
index 2323936..11f3008 100644
--- a/src/H5Fprivate.h
+++ b/src/H5Fprivate.h
@@ -248,12 +248,12 @@ typedef struct H5F_blk_aggr_t H5F_blk_aggr_t;
 #define H5F_FCPL(F)             ((F)->shared->fcpl_id)
 #define H5F_SIZEOF_ADDR(F)      ((F)->shared->sizeof_addr)
 #define H5F_SIZEOF_SIZE(F)      ((F)->shared->sizeof_size)
-#define H5F_SYM_LEAF_K(F)       ((F)->shared->sym_leaf_k)
-#define H5F_KVALUE(F,T)         ((F)->shared->btree_k[(T)->id])
+#define H5F_SYM_LEAF_K(F)       ((F)->shared->sblock->sym_leaf_k)
+#define H5F_KVALUE(F,T)         ((F)->shared->sblock->btree_k[(T)->id])
 #define H5F_RDCC_NSLOTS(F)      ((F)->shared->rdcc_nslots)
 #define H5F_RDCC_NBYTES(F)      ((F)->shared->rdcc_nbytes)
 #define H5F_RDCC_W0(F)          ((F)->shared->rdcc_w0)
-#define H5F_BASE_ADDR(F)        ((F)->shared->base_addr)
+#define H5F_BASE_ADDR(F)        ((F)->shared->sblock->base_addr)
 #define H5F_GRP_BTREE_SHARED(F) ((F)->shared->grp_btree_shared)
 #define H5F_SIEVE_BUF_SIZE(F)   ((F)->shared->sieve_buf_size)
 #define H5F_GC_REF(F)           ((F)->shared->gc_ref)
@@ -534,6 +534,9 @@ H5_DLL herr_t H5F_sfile_assert_num(unsigned n);
 H5_DLL H5F_t *H5F_fake_alloc(size_t sizeof_size);
 H5_DLL herr_t H5F_fake_free(H5F_t *f);
 
+/* Superblock related routines */
+H5_DLL herr_t H5F_super_dirty(H5F_t *f);
+
 /* Parallel I/O (i.e. MPI) related routines */
 #ifdef H5_HAVE_PARALLEL
 H5_DLL int H5F_mpi_get_rank(const H5F_t *f);
diff --git a/src/H5Fquery.c b/src/H5Fquery.c
index 564a088..93f2d6e 100644
--- a/src/H5Fquery.c
+++ b/src/H5Fquery.c
@@ -261,8 +261,9 @@ H5F_sym_leaf_k(const H5F_t *f)
 
     HDassert(f);
     HDassert(f->shared);
+    HDassert(f->shared->sblock);
 
-    FUNC_LEAVE_NOAPI(f->shared->sym_leaf_k)
+    FUNC_LEAVE_NOAPI(f->shared->sblock->sym_leaf_k)
 } /* end H5F_sym_leaf_k() */
 
 
@@ -292,9 +293,10 @@ H5F_Kvalue(const H5F_t *f, const H5B_class_t *type)
 
     HDassert(f);
     HDassert(f->shared);
+    HDassert(f->shared->sblock);
     HDassert(type);
 
-    FUNC_LEAVE_NOAPI(f->shared->btree_k[type->id])
+    FUNC_LEAVE_NOAPI(f->shared->sblock->btree_k[type->id])
 } /* end H5F_Kvalue() */
 
 
@@ -413,8 +415,9 @@ H5F_get_base_addr(const H5F_t *f)
 
     HDassert(f);
     HDassert(f->shared);
+    HDassert(f->shared->sblock);
 
-    FUNC_LEAVE_NOAPI(f->shared->base_addr)
+    FUNC_LEAVE_NOAPI(f->shared->sblock->base_addr)
 } /* end H5F_get_base_addr() */
 
 
diff --git a/src/H5Fsuper.c b/src/H5Fsuper.c
index f5973e9..b0096cb 100644
--- a/src/H5Fsuper.c
+++ b/src/H5Fsuper.c
@@ -26,14 +26,13 @@
 /***********/
 /* Headers */
 /***********/
-#include "H5private.h"		/* Generic Functions			*/
-#include "H5Eprivate.h"		/* Error handling		  	*/
-#include "H5Fpkg.h"             /* File access				*/
-#include "H5FDprivate.h"	/* File drivers				*/
-#include "H5Iprivate.h"		/* IDs			  		*/
-#include "H5MFprivate.h"	/* File memory management		*/
-#include "H5MMprivate.h"	/* Memory management			*/
-#include "H5Pprivate.h"		/* Property lists			*/
+#include "H5private.h"		/* Generic Functions                    */
+#include "H5ACprivate.h"        /* Metadata cache                       */
+#include "H5Eprivate.h"		/* Error handling                       */
+#include "H5Fpkg.h"             /* File access                          */
+#include "H5FDprivate.h"	/* File drivers                         */
+#include "H5Iprivate.h"		/* IDs                                  */
+#include "H5Pprivate.h"		/* Property lists                       */
 #include "H5SMprivate.h"        /* Shared Object Header Messages        */
 
 
@@ -41,61 +40,6 @@
 /* Local Macros */
 /****************/
 
-/* Superblock sizes for various versions */
-#define H5F_SIZEOF_CHKSUM 4     /* Checksum size in the file */
-
-/* Fixed-size portion at the beginning of all superblocks */
-#define H5F_SUPERBLOCK_FIXED_SIZE ( H5F_SIGNATURE_LEN                   \
-        + 1) /* superblock version */
-
-/* Macros for computing variable-size superblock size */
-#define H5F_SUPERBLOCK_VARLEN_SIZE_COMMON                               \
-        (2  /* freespace, and root group versions */			\
-        + 1 /* reserved */                                              \
-        + 3 /* shared header vers, size of address, size of lengths */  \
-        + 1 /* reserved */                                              \
-        + 4 /* group leaf k, group internal k */                        \
-        + 4) /* consistency flags */
-#define H5F_SUPERBLOCK_VARLEN_SIZE_V0(f)                                \
-        ( H5F_SUPERBLOCK_VARLEN_SIZE_COMMON /* Common variable-length info */ \
-        + H5F_SIZEOF_ADDR(f) /* base address */                         \
-        + H5F_SIZEOF_ADDR(f) /* <unused> */				\
-        + H5F_SIZEOF_ADDR(f) /* EOF address */                          \
-        + H5F_SIZEOF_ADDR(f) /* driver block address */                 \
-        + H5G_SIZEOF_ENTRY(f)) /* root group ptr */
-#define H5F_SUPERBLOCK_VARLEN_SIZE_V1(f)                                \
-        ( H5F_SUPERBLOCK_VARLEN_SIZE_COMMON /* Common variable-length info */ \
-        + 2 /* indexed B-tree internal k */                             \
-        + 2 /* reserved */                                              \
-        + H5F_SIZEOF_ADDR(f) /* base address */                         \
-        + H5F_SIZEOF_ADDR(f) /* <unused> */				\
-        + H5F_SIZEOF_ADDR(f) /* EOF address */                          \
-        + H5F_SIZEOF_ADDR(f) /* driver block address */                 \
-        + H5G_SIZEOF_ENTRY(f)) /* root group ptr */
-#define H5F_SUPERBLOCK_VARLEN_SIZE_V2(f)                                \
-        ( 2 /* size of address, size of lengths */                      \
-        + 1 /* consistency flags */                                     \
-        + H5F_SIZEOF_ADDR(f) /* base address */                         \
-        + H5F_SIZEOF_ADDR(f) /* superblock extension address */         \
-        + H5F_SIZEOF_ADDR(f) /* EOF address */                          \
-        + H5F_SIZEOF_ADDR(f) /* root group object header address */     \
-        + H5F_SIZEOF_CHKSUM) /* superblock checksum (keep this last) */
-#define H5F_SUPERBLOCK_VARLEN_SIZE(v, f) (				\
-        (v == 0 ? H5F_SUPERBLOCK_VARLEN_SIZE_V0(f) : 0)			\
-        + (v == 1 ? H5F_SUPERBLOCK_VARLEN_SIZE_V1(f) : 0)               \
-        + (v == 2 ? H5F_SUPERBLOCK_VARLEN_SIZE_V2(f) : 0))
-
-/* Total size of superblock, depends on superblock version */
-#define H5F_SUPERBLOCK_SIZE(v, f) ( H5F_SUPERBLOCK_FIXED_SIZE           \
-        + H5F_SUPERBLOCK_VARLEN_SIZE(v, f))
-
-/* Driver info block macros */
-#define H5F_DRVINFOBLOCK_HDR_SIZE 16
-
-/* Maximum size of super-block buffers */
-#define H5F_MAX_SUPERBLOCK_SIZE  134
-#define H5F_MAX_DRVINFOBLOCK_SIZE  1024
-
 
 /******************/
 /* Local Typedefs */
@@ -111,9 +55,6 @@
 /* Local Prototypes */
 /********************/
 static herr_t H5F_super_ext_create(H5F_t *f, hid_t dxpl_id, H5O_loc_t *ext_ptr);
-static herr_t H5F_super_ext_open(H5F_t *f, H5O_loc_t *ext_ptr);
-static herr_t H5F_super_ext_write_msg(H5F_t *f, hid_t dxpl_id, void *mesg, unsigned id, hbool_t may_create);
-static herr_t H5F_super_ext_close(H5F_t *f, H5O_loc_t *ext_ptr);
 
 
 /*********************/
@@ -125,6 +66,9 @@ static herr_t H5F_super_ext_close(H5F_t *f, H5O_loc_t *ext_ptr);
 /* Library Private Variables */
 /*****************************/
 
+/* Declare a free list to manage the H5F_super_t struct */
+H5FL_DEFINE(H5F_super_t);
+
 
 /*******************/
 /* Local Variables */
@@ -238,15 +182,17 @@ H5F_super_ext_create(H5F_t *f, hid_t dxpl_id, H5O_loc_t *ext_ptr)
 
     /* Sanity check */
     HDassert(f);
+    HDassert(f->shared);
+    HDassert(f->shared->sblock);
+    HDassert(!H5F_addr_defined(f->shared->sblock->ext_addr));
     HDassert(ext_ptr);
-    HDassert(!H5F_addr_defined(f->shared->extension_addr));
 
     H5O_loc_reset(ext_ptr);
     if(H5O_create(f, dxpl_id, 0, H5P_GROUP_CREATE_DEFAULT, ext_ptr) < 0)
 	HGOTO_ERROR(H5E_OHDR, H5E_CANTCREATE, FAIL, "unable to create superblock extension")
 
     /* Record the address of the superblock extension */
-    f->shared->extension_addr = ext_ptr->addr;
+    f->shared->sblock->ext_addr = ext_ptr->addr;
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -265,8 +211,8 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
-H5F_super_ext_open(H5F_t *f, H5O_loc_t *ext_ptr)
+herr_t
+H5F_super_ext_open(H5F_t *f, haddr_t ext_addr, H5O_loc_t *ext_ptr)
 {
     herr_t ret_value = SUCCEED;         /* Return value */
 
@@ -274,17 +220,17 @@ H5F_super_ext_open(H5F_t *f, H5O_loc_t *ext_ptr)
 
     /* Sanity check */
     HDassert(f);
+    HDassert(H5F_addr_defined(ext_addr));
     HDassert(ext_ptr);
-    HDassert(H5F_addr_defined(f->shared->extension_addr));
 
     /* Set up "fake" object location for superblock extension */
     H5O_loc_reset(ext_ptr);
     ext_ptr->file = f;
-    ext_ptr->addr = f->shared->extension_addr;
+    ext_ptr->addr = ext_addr;
 
     /* Open the superblock extension object header */
     if(H5O_open(ext_ptr) < 0)
-	HGOTO_ERROR(H5E_OHDR, H5E_CANTOPENFILE, FAIL, "unable to open superblock extension")
+	HGOTO_ERROR(H5E_OHDR, H5E_CANTOPENOBJ, FAIL, "unable to open superblock extension")
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -303,7 +249,7 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-static herr_t 
+herr_t 
 H5F_super_ext_close(H5F_t *f, H5O_loc_t *ext_ptr)
 {
     herr_t ret_value = SUCCEED;         /* Return value */
@@ -317,7 +263,7 @@ H5F_super_ext_close(H5F_t *f, H5O_loc_t *ext_ptr)
     /* Twiddle the number of open objects to avoid closing the file. */
     f->nopen_objs++;
     if(H5O_close(ext_ptr) < 0)
-        HGOTO_ERROR(H5E_OHDR, H5E_CANTRELEASE, FAIL, "unable to close superblock extension")
+        HGOTO_ERROR(H5E_OHDR, H5E_CANTCLOSEOBJ, FAIL, "unable to close superblock extension")
     f->nopen_objs--;
 
 done:
@@ -345,421 +291,44 @@ done:
 herr_t
 H5F_super_read(H5F_t *f, hid_t dxpl_id)
 {
-    uint8_t             sbuf[H5F_MAX_SUPERBLOCK_SIZE];     /* Buffer for superblock */
-    H5P_genplist_t     *c_plist;            /* File creation property list  */
-    H5F_file_t         *shared;             /* shared part of `file'        */
-    H5FD_t             *lf;                 /* file driver part of `shared' */
-    haddr_t             abs_super_addr;     /* Absolute offset of superblock in file */
-    haddr_t             stored_eoa;         /*relative end-of-addr in file  */
-    haddr_t             eof;                /*end of file address           */
-    size_t              sizeof_addr;        /* Size of offsets in the file (in bytes) */
-    size_t              sizeof_size;        /* Size of lengths in the file (in bytes) */
-    const size_t        fixed_size = H5F_SUPERBLOCK_FIXED_SIZE; /*fixed sizeof superblock   */
-    size_t              variable_size;      /*variable sizeof superblock    */
-    uint8_t            *p;                  /* Temporary pointer into encoding buffer */
-    unsigned            super_vers;         /* Superblock version          */
-    herr_t              ret_value = SUCCEED;
+    H5F_super_t *       sblock = NULL;      /* superblock structure                         */
+    unsigned            sblock_flags = H5AC__NO_FLAGS_SET;       /* flags used in superblock unprotect call      */
+    H5AC_protect_t      rw;                 /* read/write permissions for file              */
+    hbool_t             dirtied = FALSE;    /* Bool for sblock protect call                 */
+    herr_t              ret_value = SUCCEED; /* return value                                */
 
     FUNC_ENTER_NOAPI(H5F_super_read, FAIL)
 
-    /* Short cuts */
-    shared = f->shared;
-    lf = shared->lf;
-
-    /* Get the shared file creation property list */
-    if(NULL == (c_plist = (H5P_genplist_t *)H5I_object(shared->fcpl_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "can't get property list")
-
     /* Find the superblock */
-    if(HADDR_UNDEF == (abs_super_addr = H5F_locate_signature(lf, dxpl_id)))
+    if(HADDR_UNDEF == (f->shared->super_addr = H5F_locate_signature(f->shared->lf, dxpl_id)))
         HGOTO_ERROR(H5E_FILE, H5E_NOTHDF5, FAIL, "unable to find file signature")
 
-    /* Read fixed-size portion of the superblock */
-    p = sbuf;
-    if(H5FD_set_eoa(lf, H5FD_MEM_SUPER, abs_super_addr + fixed_size) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "set end of space allocation request failed")
-    if(H5FD_read(lf, dxpl_id, H5FD_MEM_SUPER, abs_super_addr, fixed_size, p) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_READERROR, FAIL, "unable to read superblock")
-
-    /* Skip over signature (already checked when locating the superblock) */
-    p += H5F_SIGNATURE_LEN;
-
-    /* Superblock version */
-    super_vers = *p++;
-    if(super_vers > HDF5_SUPERBLOCK_VERSION_LATEST)
-        HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad superblock version number")
-    if(H5P_set(c_plist, H5F_CRT_SUPER_VERS_NAME, &super_vers) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set superblock version")
-
-    /* Sanity check */
-    HDassert(((size_t)(p - sbuf)) == fixed_size);
-
-    /* Determine the size of the variable-length part of the superblock */
-    variable_size = H5F_SUPERBLOCK_VARLEN_SIZE(super_vers, f);
-    HDassert(variable_size > 0);
-    HDassert(fixed_size + variable_size <= sizeof(sbuf));
-
-    /* Read in variable-sized portion of superblock */
-    if(H5FD_set_eoa(lf, H5FD_MEM_SUPER, abs_super_addr + fixed_size + variable_size) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "set end of space allocation request failed")
-    if(H5FD_read(lf, dxpl_id, H5FD_MEM_SUPER, abs_super_addr + fixed_size, variable_size, p) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to read superblock")
-
-    /* Check for older version of superblock format */
-    if(super_vers < HDF5_SUPERBLOCK_VERSION_2) {
-        uint32_t	status_flags;	    /* File status flags	   */
-        unsigned        btree_k[H5B_NUM_BTREE_ID];  /* B-tree internal node 'K' values */
-        unsigned        sym_leaf_k;         /* Symbol table leaf node's 'K' value */
-
-        /* Freespace version (hard-wired) */
-        if(HDF5_FREESPACE_VERSION != *p++)
-            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad free space version number")
-
-        /* Root group version number (hard-wired) */
-        if(HDF5_OBJECTDIR_VERSION != *p++)
-            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad object directory version number")
-
-        /* Skip over reserved byte */
-        p++;
-
-        /* Shared header version number (hard-wired) */
-        if(HDF5_SHAREDHEADER_VERSION != *p++)
-            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad shared-header format version number")
-
-        /* Size of file addresses */
-        sizeof_addr = *p++;
-        if(sizeof_addr != 2 && sizeof_addr != 4 &&
-                sizeof_addr != 8 && sizeof_addr != 16 && sizeof_addr != 32)
-            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad byte number in an address")
-        if(H5P_set(c_plist, H5F_CRT_ADDR_BYTE_NUM_NAME, &sizeof_addr) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set byte number in an address")
-        shared->sizeof_addr = sizeof_addr;  /* Keep a local copy also */
-
-        /* Size of file sizes */
-        sizeof_size = *p++;
-        if(sizeof_size != 2 && sizeof_size != 4 &&
-                sizeof_size != 8 && sizeof_size != 16 && sizeof_size != 32)
-            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad byte number for object size")
-        if(H5P_set(c_plist, H5F_CRT_OBJ_BYTE_NUM_NAME, &sizeof_size) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set byte number for object size")
-        shared->sizeof_size = sizeof_size;  /* Keep a local copy also */
-
-        /* Skip over reserved byte */
-        p++;
-
-        /* Various B-tree sizes */
-        UINT16DECODE(p, sym_leaf_k);
-        if(sym_leaf_k == 0)
-            HGOTO_ERROR(H5E_FILE, H5E_BADRANGE, FAIL, "bad symbol table leaf node 1/2 rank")
-        if(H5P_set(c_plist, H5F_CRT_SYM_LEAF_NAME, &sym_leaf_k) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set rank for symbol table leaf nodes")
-        shared->sym_leaf_k = sym_leaf_k;    /* Keep a local copy also */
-
-        /* Need 'get' call to set other array values */
-        if(H5P_get(c_plist, H5F_CRT_BTREE_RANK_NAME, btree_k) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get rank for btree internal nodes")
-        UINT16DECODE(p, btree_k[H5B_SNODE_ID]);
-        if(btree_k[H5B_SNODE_ID] == 0)
-            HGOTO_ERROR(H5E_FILE, H5E_BADRANGE, FAIL, "bad 1/2 rank for btree internal nodes")
-        /*
-         * Delay setting the value in the property list until we've checked
-         * for the indexed storage B-tree internal 'K' value later.
-         */
-
-        /* File status flags (not really used yet) */
-        UINT32DECODE(p, status_flags);
-        HDassert(status_flags <= 255);
-        shared->status_flags = (uint8_t)status_flags;
-        if(shared->status_flags & ~H5F_SUPER_ALL_FLAGS)
-            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad flag value for superblock")
-
-        /*
-         * If the superblock version # is greater than 0, read in the indexed
-         * storage B-tree internal 'K' value
-         */
-        if(super_vers > HDF5_SUPERBLOCK_VERSION_DEF) {
-            UINT16DECODE(p, btree_k[H5B_CHUNK_ID]);
-            /* Reserved bytes are present only in version 1 */
-            if(super_vers == HDF5_SUPERBLOCK_VERSION_1)
-                p += 2;   /* reserved */
-        } /* end if */
-        else
-            btree_k[H5B_CHUNK_ID] = HDF5_BTREE_CHUNK_IK_DEF;
-
-        /* Set the B-tree internal node values, etc */
-        if(H5P_set(c_plist, H5F_CRT_BTREE_RANK_NAME, btree_k) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set rank for btree internal nodes")
-        HDmemcpy(shared->btree_k, btree_k, sizeof(unsigned) * (size_t)H5B_NUM_BTREE_ID);    /* Keep a local copy also */
-
-        /* Remainder of "variable-sized" portion of superblock */
-        H5F_addr_decode(f, (const uint8_t **)&p, &shared->base_addr/*out*/);
-        H5F_addr_decode(f, (const uint8_t **)&p, &shared->extension_addr/*out*/);
-        H5F_addr_decode(f, (const uint8_t **)&p, &stored_eoa/*out*/);
-        H5F_addr_decode(f, (const uint8_t **)&p, &shared->driver_addr/*out*/);
-
-        /* Decode the symbol table entry */
-        if(H5G_root_ent_decode(f, (const uint8_t **)&p) < 0)
-            HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to read root symbol entry")
-
-        /*
-         * Check if superblock address is different from base address and
-         * adjust base address and "end of address" address if so.
-         */
-        if(!H5F_addr_eq(abs_super_addr, shared->base_addr)) {
-            /* Check if the superblock moved earlier in the file */
-            if(H5F_addr_lt(abs_super_addr, shared->base_addr))
-                stored_eoa -= (shared->base_addr - abs_super_addr);
-            else
-                /* The superblock moved later in the file */
-                stored_eoa += (abs_super_addr - shared->base_addr);
-
-            shared->base_addr = abs_super_addr;
-        } /* end if */
-
-        /* Set the base address for the file in the VFD now, after adjusting
-         *  space for possible offsets of the HDF5 data in the file.
-         */
-        if(H5FD_set_base_addr(lf, shared->base_addr) < 0)
-            HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "failed to set base address for file driver")
-
-        /* This step is for h5repart tool only. If user wants to change file driver
-         *  from family to sec2 while using h5repart, set the driver address to
-         *  undefined to let the library ignore the family driver information saved
-         *  in the superblock.
-         */
-        if(shared->fam_to_sec2)
-            shared->driver_addr = HADDR_UNDEF;
-
-        /* Decode the optional driver information block */
-        if(H5F_addr_defined(shared->driver_addr)) {
-            uint8_t dbuf[H5F_MAX_DRVINFOBLOCK_SIZE];     /* Buffer for driver info block */
-            char drv_name[9];       /* Name of driver */
-            unsigned drv_vers;      /* Version of driver info block */
-            size_t drv_variable_size; /* Size of variable-length portion of driver info block, in bytes */
-
-            /* Read in fixed-sized portion of driver info block */
-            p = dbuf;
-            if(H5FD_set_eoa(lf, H5FD_MEM_SUPER, shared->driver_addr + H5F_DRVINFOBLOCK_HDR_SIZE) < 0)
-                HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "set end of space allocation request failed")
-            if(H5FD_read(lf, dxpl_id, H5FD_MEM_SUPER, shared->driver_addr, (size_t)H5F_DRVINFOBLOCK_HDR_SIZE, p) < 0)
-                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to read driver information block")
-
-            /* Version number */
-            drv_vers = *p++;
-            if(drv_vers != HDF5_DRIVERINFO_VERSION_0)
-                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "bad driver information block version number")
-
-            p += 3; /* reserved bytes */
-
-            /* Driver info size */
-            UINT32DECODE(p, drv_variable_size);
-
-            /* Sanity check */
-            HDassert(H5F_DRVINFOBLOCK_HDR_SIZE + drv_variable_size <= sizeof(dbuf));
-
-            /* Driver name and/or version */
-            HDstrncpy(drv_name, (const char *)p, (size_t)8);
-            drv_name[8] = '\0';
-            p += 8; /* advance past name/version */
-
-            /* Check if driver matches driver information saved. Unfortunately, we can't push this
-             * function to each specific driver because we're checking if the driver is correct.
-             */
-            if(!HDstrncmp(drv_name, "NCSAfami", (size_t)8) && HDstrcmp(lf->cls->name, "family"))
-                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "family driver should be used")
-            if(!HDstrncmp(drv_name, "NCSAmult", (size_t)8) && HDstrcmp(lf->cls->name, "multi"))
-                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "multi driver should be used")
-
-            /* Read in variable-sized portion of driver info block */
-            if(H5FD_set_eoa(lf, H5FD_MEM_SUPER, shared->driver_addr + H5F_DRVINFOBLOCK_HDR_SIZE + drv_variable_size) < 0)
-                HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "set end of space allocation request failed")
-            if(H5FD_read(lf, dxpl_id, H5FD_MEM_SUPER, shared->driver_addr + H5F_DRVINFOBLOCK_HDR_SIZE, drv_variable_size, p) < 0)
-                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to read file driver information")
-
-            /* Decode driver information */
-            if(H5FD_sb_decode(lf, drv_name, p) < 0)
-                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to decode driver information")
-        } /* end if */
-    } /* end if */
-    else {
-        uint32_t computed_chksum;       /* Computed checksum  */
-        uint32_t read_chksum;           /* Checksum read from file  */
-
-        /* Size of file addresses */
-        sizeof_addr = *p++;
-        if(sizeof_addr != 2 && sizeof_addr != 4 &&
-                sizeof_addr != 8 && sizeof_addr != 16 && sizeof_addr != 32)
-            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad byte number in an address")
-        if(H5P_set(c_plist, H5F_CRT_ADDR_BYTE_NUM_NAME, &sizeof_addr) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set byte number in an address")
-        shared->sizeof_addr = sizeof_addr;  /* Keep a local copy also */
-
-        /* Size of file sizes */
-        sizeof_size = *p++;
-        if(sizeof_size != 2 && sizeof_size != 4 &&
-                sizeof_size != 8 && sizeof_size != 16 && sizeof_size != 32)
-            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad byte number for object size")
-        if(H5P_set(c_plist, H5F_CRT_OBJ_BYTE_NUM_NAME, &sizeof_size) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set byte number for object size")
-        shared->sizeof_size = sizeof_size;  /* Keep a local copy also */
-
-        /* File status flags (not really used yet) */
-        shared->status_flags = *p++;
-        if(shared->status_flags & ~H5F_SUPER_ALL_FLAGS)
-            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad flag value for superblock")
-
-        /* Base, superblock extension, end of file & root group object header addresses */
-        H5F_addr_decode(f, (const uint8_t **)&p, &shared->base_addr/*out*/);
-        H5F_addr_decode(f, (const uint8_t **)&p, &shared->extension_addr/*out*/);
-        H5F_addr_decode(f, (const uint8_t **)&p, &stored_eoa/*out*/);
-        H5F_addr_decode(f, (const uint8_t **)&p, &shared->root_addr/*out*/);
-
-        /* Compute checksum for superblock */
-        computed_chksum = H5_checksum_metadata(sbuf, (size_t)(p - sbuf), 0);
-
-        /* Decode checksum */
-        UINT32DECODE(p, read_chksum);
-
-        /* Verify correct checksum */
-        if(read_chksum != computed_chksum)
-            HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "bad checksum on driver information block")
-
-        /*
-         * Check if superblock address is different from base address and
-         * adjust base address and "end of address" address if so.
-         */
-        if(!H5F_addr_eq(abs_super_addr, shared->base_addr)) {
-            /* Check if the superblock moved earlier in the file */
-            if(H5F_addr_lt(abs_super_addr, shared->base_addr))
-                stored_eoa -= (shared->base_addr - abs_super_addr);
-            else
-                /* The superblock moved later in the file */
-                stored_eoa += (abs_super_addr - shared->base_addr);
-
-            shared->base_addr = abs_super_addr;
-        } /* end if */
-
-        /* Set the base address for the file in the VFD now, after adjusting
-         *  space for possible offsets of the HDF5 data in the file.
-         */
-        if(H5FD_set_base_addr(lf, shared->base_addr) < 0)
-            HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "failed to set base address for file driver")
-    } /* end else */
-
-    /*
-     * The user-defined data is the area of the file before the base
-     * address.
-     */
-    if(H5P_set(c_plist, H5F_CRT_USER_BLOCK_NAME, &shared->base_addr) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set userblock size")
-
-    /*
-     * Make sure that the data is not truncated. One case where this is
-     * possible is if the first file of a family of files was opened
-     * individually.
-     */
-    if(HADDR_UNDEF == (eof = H5FD_get_eof(lf)))
-        HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to determine file size")
-    /* (Account for the stored EOA being absolute offset -QAK) */
-    if((eof + H5F_BASE_ADDR(f)) < stored_eoa)
-        HGOTO_ERROR(H5E_FILE, H5E_TRUNCATED, FAIL, "truncated file")
-
-    /*
-     * Tell the file driver how much address space has already been
-     * allocated so that it knows how to allocate additional memory.
-     */
-    /* (Account for the stored EOA being absolute offset -NAF) */
-    if(H5FD_set_eoa(lf, H5FD_MEM_SUPER, stored_eoa - H5F_BASE_ADDR(f)) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to set end-of-address marker for file")
-
-    /* Read the file's superblock extension, if there is one. */
-    if(H5F_addr_defined(shared->extension_addr)) {
-        H5O_loc_t ext_loc;      /* "Object location" for superblock extension */
-        H5O_btreek_t btreek;    /* v1 B-tree 'K' value message from superblock extension */
-        H5O_drvinfo_t drvinfo;  /* Driver info message from superblock extension */
-        htri_t status;          /* Status for message existing */
-
-        /* Sanity check - superblock extension should only be defined for
-         *      superblock version >= 2.
-         */
-        HDassert(super_vers >= HDF5_SUPERBLOCK_VERSION_2);
-
-        /* Check for superblock extension being located "outside" the stored
-         *      'eoa' value, which can occur with the split/multi VFD.
-         */
-        if(H5F_addr_gt(shared->extension_addr, stored_eoa)) {
-            /* Set the 'eoa' for the object header memory type large enough
-             *  to give some room for a reasonably sized superblock extension.
-             *  (This is _rather_ a kludge -QAK)
-             */
-            if(H5FD_set_eoa(lf, H5FD_MEM_OHDR, (haddr_t)(shared->extension_addr + 1024)) < 0)
-                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to set end-of-address marker for file")
-        } /* end if */
+    /* Determine file intent for superblock protect */
+    if(H5F_INTENT(f) & H5F_ACC_RDWR)
+        rw = H5AC_WRITE;
+    else
+        rw = H5AC_READ;
 
-        /* Open the superblock extension */
-	if(H5F_super_ext_open(f, &ext_loc) < 0)
-            HGOTO_ERROR(H5E_FILE, H5E_CANTOPENOBJ, FAIL, "unable to start file's superblock extension")
-
-        /* Check for the extension having a 'driver info' message */
-        if((status = H5O_msg_exists(&ext_loc, H5O_DRVINFO_ID, dxpl_id)) < 0)
-            HGOTO_ERROR(H5E_FILE, H5E_CANTGET, FAIL, "unable to read object header")
-        if(status) {
-            /* Retrieve the 'driver info' structure */
-            if(NULL == H5O_msg_read(&ext_loc, H5O_DRVINFO_ID, &drvinfo, dxpl_id))
-                HGOTO_ERROR(H5E_FILE, H5E_CANTGET, FAIL, "driver info message not present")
-
-            /* Check if driver matches driver information saved. Unfortunately, we can't push this
-             * function to each specific driver because we're checking if the driver is correct.
-             */
-            if(!HDstrncmp(drvinfo.name, "NCSAfami", (size_t)8) && HDstrcmp(lf->cls->name, "family"))
-                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "family driver should be used")
-            if(!HDstrncmp(drvinfo.name, "NCSAmult", (size_t)8) && HDstrcmp(lf->cls->name, "multi"))
-                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "multi driver should be used")
-
-            /* Decode driver information */
-            if(H5FD_sb_decode(lf, drvinfo.name, drvinfo.buf) < 0)
-                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to decode driver information")
-
-            /* Reset driver info message */
-            H5O_msg_reset(H5O_DRVINFO_ID, &drvinfo);
-        } /* end if */
+    /* Look up the superblock */
+    if(NULL == (sblock = (H5F_super_t *)H5AC_protect(f, dxpl_id, H5AC_SUPERBLOCK, f->shared->super_addr, NULL, &dirtied, rw)))
+        HGOTO_ERROR(H5E_CACHE, H5E_CANTPROTECT, FAIL, "unable to load superblock")
+    
+    /* Mark the superblock dirty if it was modified during loading or VFD indicated to do so */
+    if((H5AC_WRITE == rw) && (dirtied || H5F_HAS_FEATURE(f, H5FD_FEAT_DIRTY_SBLK_LOAD)))
+        sblock_flags |= H5AC__DIRTIED_FLAG;
 
-        /* Read in the shared OH message information if there is any */
-        if(H5SM_get_info(&ext_loc, c_plist, dxpl_id) < 0)
-            HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to read SOHM table information")
-
-        /* Check for the extension having a 'v1 B-tree "K"' message */
-        if((status = H5O_msg_exists(&ext_loc, H5O_BTREEK_ID, dxpl_id)) < 0)
-            HGOTO_ERROR(H5E_FILE, H5E_CANTGET, FAIL, "unable to read object header")
-        if(status) {
-            /* Retrieve the 'v1 B-tree "K"' structure */
-            if(NULL == H5O_msg_read(&ext_loc, H5O_BTREEK_ID, &btreek, dxpl_id))
-                HGOTO_ERROR(H5E_FILE, H5E_CANTGET, FAIL, "v1 B-tree 'K' info message not present")
-
-            /* Set non-default v1 B-tree 'K' value info from file */
-            shared->btree_k[H5B_CHUNK_ID] = btreek.btree_k[H5B_CHUNK_ID];
-            shared->btree_k[H5B_SNODE_ID] = btreek.btree_k[H5B_SNODE_ID];
-            shared->sym_leaf_k = btreek.sym_leaf_k;
-
-            /* Set non-default v1 B-tree 'K' values in the property list */
-            if(H5P_set(c_plist, H5F_CRT_BTREE_RANK_NAME, btreek.btree_k) < 0)
-                HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set rank for btree internal nodes")
-            if(H5P_set(c_plist, H5F_CRT_SYM_LEAF_NAME, &btreek.sym_leaf_k) < 0)
-                HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set rank for symbol table leaf nodes")
-        } /* end if */
-        else {
-            /* No non-default v1 B-tree 'K' value info in file, use defaults */
-            shared->btree_k[H5B_CHUNK_ID] = HDF5_BTREE_CHUNK_IK_DEF;
-            shared->btree_k[H5B_SNODE_ID] = HDF5_BTREE_SNODE_IK_DEF;
-            shared->sym_leaf_k = H5F_CRT_SYM_LEAF_DEF;
-        } /* end if */
+    /* Pin the superblock in the cache */
+    if(H5AC_pin_protected_entry(f, sblock) < 0)
+        HGOTO_ERROR(H5E_FSPACE, H5E_CANTPIN, FAIL, "unable to pin superblock")
 
-        /* Close superblock extension */
-	if(H5F_super_ext_close(f, &ext_loc) < 0)
-	    HGOTO_ERROR(H5E_FILE, H5E_CANTRELEASE, FAIL, "unable to close file's superblock extension")
-    } /* end if */
+    /* Set the pointer to the pinned superblock */
+    f->shared->sblock = sblock;
 
 done:
+    /* Release the superblock */
+    if(sblock && H5AC_unprotect(f, dxpl_id, H5AC_SUPERBLOCK, f->shared->super_addr, sblock, sblock_flags) < 0)
+        HDONE_ERROR(H5E_CACHE, H5E_CANTUNPROTECT, FAIL, "unable to close superblock")
+
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5F_super_read() */
 
@@ -783,21 +352,64 @@ done:
 herr_t
 H5F_super_init(H5F_t *f, hid_t dxpl_id)
 {
-    H5P_genplist_t *plist;              /* File creation property list */
-    hsize_t         userblock_size;     /* Size of userblock, in bytes */
-    hsize_t         superblock_size;    /* Size of superblock, in bytes */
-    size_t          driver_size;        /* Size of driver info block (bytes) */
-    unsigned        super_vers;         /* Superblock version */
-    haddr_t         super_addr;         /* Address of superblock */
+    H5F_super_t    *sblock = NULL;      /* Superblock cache structure                 */
+    hbool_t         sblock_in_cache = FALSE;    /* Whether the superblock has been inserted into the metadata cache */
+    H5P_genplist_t *plist;              /* File creation property list                */
+    hsize_t         userblock_size;     /* Size of userblock, in bytes                */
+    hsize_t         superblock_size;    /* Size of superblock, in bytes               */
+    size_t          driver_size;        /* Size of driver info block (bytes)          */
+    unsigned super_vers = HDF5_SUPERBLOCK_VERSION_DEF; /* Superblock version for file */
+    haddr_t         super_addr;         /* Address of superblock                      */
     hbool_t         need_ext;           /* Whether the superblock extension is needed */
-    herr_t          ret_value = SUCCEED;
+    herr_t          ret_value = SUCCEED; /* Return Value                              */
 
     FUNC_ENTER_NOAPI(H5F_super_init, FAIL)
 
+    /* Allocate space for the superblock */
+    if(NULL == (sblock = H5FL_CALLOC(H5F_super_t)))
+        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
+
+    /* Initialize various address information */
+    sblock->base_addr = HADDR_UNDEF;
+    sblock->ext_addr = HADDR_UNDEF;
+    sblock->driver_addr = HADDR_UNDEF;
+    sblock->root_addr = HADDR_UNDEF;
+
     /* Get the shared file creation property list */
     if(NULL == (plist = (H5P_genplist_t *)H5I_object(f->shared->fcpl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list")
 
+    /* Initialize sym_leaf_k */
+    if(H5P_get(plist, H5F_CRT_SYM_LEAF_NAME, &sblock->sym_leaf_k) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get byte number for object size")
+
+    /* Initialize btree_k */
+    if(H5P_get(plist, H5F_CRT_BTREE_RANK_NAME, &sblock->btree_k[0]) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get rank for btree internal nodes")
+
+    /* Bump superblock version if we are to use the latest version of the format */
+    if(f->shared->latest_format)
+        super_vers = HDF5_SUPERBLOCK_VERSION_LATEST;
+    /* Bump superblock version to create superblock extension for SOHM info */
+    else if(f->shared->sohm_nindexes > 0)
+        super_vers = HDF5_SUPERBLOCK_VERSION_2;
+    /* Check for non-default indexed storage B-tree internal 'K' value
+     * and set the version # of the superblock to 1 if it is a non-default
+     * value.
+     */
+    else if(sblock->btree_k[H5B_CHUNK_ID] != HDF5_BTREE_CHUNK_IK_DEF)
+        super_vers = HDF5_SUPERBLOCK_VERSION_1;
+
+    /* If a newer superblock version is required, set it here */
+    if(super_vers != HDF5_SUPERBLOCK_VERSION_DEF) {
+        H5P_genplist_t *c_plist;              /* Property list */
+
+        if(NULL == (c_plist = (H5P_genplist_t *)H5I_object(f->shared->fcpl_id)))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not property list")
+        if(H5P_set(c_plist, H5F_CRT_SUPER_VERS_NAME, &super_vers) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set superblock version")
+    } /* end if */
+
     /*
      * The superblock starts immediately after the user-defined
      * header, which we have already insured is a proper size. The
@@ -806,8 +418,9 @@ H5F_super_init(H5F_t *f, hid_t dxpl_id)
      */
     if(H5P_get(plist, H5F_CRT_USER_BLOCK_NAME, &userblock_size) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTGET, FAIL, "unable to get userblock size")
-    f->shared->base_addr = userblock_size;
-    f->shared->status_flags = 0;
+
+    sblock->base_addr = userblock_size;
+    sblock->status_flags = 0;
 
     /* Reserve space for the userblock */
     if(H5FD_set_eoa(f->shared->lf, H5FD_MEM_SUPER, userblock_size) < 0)
@@ -816,12 +429,11 @@ H5F_super_init(H5F_t *f, hid_t dxpl_id)
     /* Set the base address for the file in the VFD now, after allocating
      *  space for userblock.
      */
-    if(H5FD_set_base_addr(f->shared->lf, f->shared->base_addr) < 0)
+    if(H5FD_set_base_addr(f->shared->lf, sblock->base_addr) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "failed to set base address for file driver")
 
-    /* Grab superblock version from property list */
-    if(H5P_get(plist, H5F_CRT_SUPER_VERS_NAME, &super_vers) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get superblock version")
+    /* Save a local copy of the superblock version number */
+    sblock->super_vers = super_vers;
 
     /* Compute the size of the superblock */
     superblock_size = H5F_SUPERBLOCK_SIZE(super_vers, f);
@@ -835,7 +447,7 @@ H5F_super_init(H5F_t *f, hid_t dxpl_id)
          * The file driver information block begins immediately after the
          * superblock. (relative to base address in file)
          */
-        f->shared->driver_addr = superblock_size;
+        sblock->driver_addr = superblock_size;
     } /* end if */
 
     /*
@@ -846,11 +458,22 @@ H5F_super_init(H5F_t *f, hid_t dxpl_id)
      */
     if(super_vers < HDF5_SUPERBLOCK_VERSION_2)
         superblock_size += driver_size;
-    super_addr = H5MF_alloc(f, H5FD_MEM_SUPER, dxpl_id, superblock_size);
-    if(HADDR_UNDEF == super_addr)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to allocate file space for userblock and/or superblock")
-    if(0 != super_addr)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "file driver failed to allocate userblock and/or superblock at address zero")
+
+    /* Reserve space in the file for the superblock, instead of allocating it */
+    if(H5FD_set_eoa(f->shared->lf, H5FD_MEM_SUPER, superblock_size) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to set EOA value for superblock")
+
+    /* Set the superblock's address, it must be immediately after any userblock */
+    super_addr = (haddr_t)0;
+
+    /* Insert superblock into cache, pinned */
+    if(H5AC_set(f, dxpl_id, H5AC_SUPERBLOCK, super_addr, sblock, H5AC__PIN_ENTRY_FLAG) < 0)
+        HGOTO_ERROR(H5E_CACHE, H5E_CANTINS, FAIL, "can't add superblock to cache")
+    sblock_in_cache = TRUE;
+
+    /* Keep a copy of the superblock info */
+    f->shared->sblock = sblock;
+    f->shared->super_addr = super_addr;
 
     /*
      * Determine if we will need a superblock extension
@@ -867,9 +490,9 @@ H5F_super_init(H5F_t *f, hid_t dxpl_id)
      */
     else if(super_vers >= HDF5_SUPERBLOCK_VERSION_2) {
         /* Check for non-default v1 B-tree 'K' values to store */
-        if(f->shared->btree_k[H5B_SNODE_ID] != HDF5_BTREE_SNODE_IK_DEF ||
-                f->shared->btree_k[H5B_CHUNK_ID] != HDF5_BTREE_CHUNK_IK_DEF ||
-                f->shared->sym_leaf_k != H5F_CRT_SYM_LEAF_DEF)
+        if(sblock->btree_k[H5B_SNODE_ID] != HDF5_BTREE_SNODE_IK_DEF ||
+                sblock->btree_k[H5B_CHUNK_ID] != HDF5_BTREE_CHUNK_IK_DEF ||
+                sblock->sym_leaf_k != H5F_CRT_SYM_LEAF_DEF)
             need_ext = TRUE;
         /* Check for driver info to store */
         else if(driver_size > 0)
@@ -905,15 +528,15 @@ H5F_super_init(H5F_t *f, hid_t dxpl_id)
         } /* end if */
 
         /* Check for non-default v1 B-tree 'K' values to store */
-        if(f->shared->btree_k[H5B_SNODE_ID] != HDF5_BTREE_SNODE_IK_DEF ||
-                f->shared->btree_k[H5B_CHUNK_ID] != HDF5_BTREE_CHUNK_IK_DEF ||
-                f->shared->sym_leaf_k != H5F_CRT_SYM_LEAF_DEF) {
+        if(sblock->btree_k[H5B_SNODE_ID] != HDF5_BTREE_SNODE_IK_DEF ||
+                sblock->btree_k[H5B_CHUNK_ID] != HDF5_BTREE_CHUNK_IK_DEF ||
+                sblock->sym_leaf_k != H5F_CRT_SYM_LEAF_DEF) {
             H5O_btreek_t btreek;        /* v1 B-tree 'K' value message for superblock extension */
 
             /* Write v1 B-tree 'K' value information to the superblock extension */
-            btreek.btree_k[H5B_CHUNK_ID] = f->shared->btree_k[H5B_CHUNK_ID];
-            btreek.btree_k[H5B_SNODE_ID] = f->shared->btree_k[H5B_SNODE_ID];
-            btreek.sym_leaf_k = f->shared->sym_leaf_k;
+            btreek.btree_k[H5B_CHUNK_ID] = sblock->btree_k[H5B_CHUNK_ID];
+            btreek.btree_k[H5B_SNODE_ID] = sblock->btree_k[H5B_SNODE_ID];
+            btreek.sym_leaf_k = sblock->sym_leaf_k;
             if(H5O_msg_create(&ext_loc, H5O_BTREEK_ID, H5O_MSG_FLAG_CONSTANT | H5O_MSG_FLAG_DONTSHARE, H5O_UPDATE_TIME, &btreek, dxpl_id) < 0)
                 HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to update v1 B-tree 'K' value header message")
         } /* end if */
@@ -943,194 +566,66 @@ H5F_super_init(H5F_t *f, hid_t dxpl_id)
     } /* end if */
 
 done:
+    /* Cleanup on failure */
+    if(ret_value < 0) {
+        /* Check if the superblock has been allocated yet */
+        if(sblock) {
+            /* Check if we've cached it already */
+            if(sblock_in_cache) {
+                /* Unpin superblock in cache */
+                if(H5AC_unpin_entry(f, sblock) < 0)
+                    HDONE_ERROR(H5E_FILE, H5E_CANTUNPIN, FAIL, "unable to unpin superblock")
+
+                /* Evict the superblock from the cache */
+                if(H5AC_expunge_entry(f, dxpl_id, H5AC_SUPERBLOCK, super_addr, H5AC__NO_FLAGS_SET) < 0)
+                    HDONE_ERROR(H5E_FILE, H5E_CANTEXPUNGE, FAIL, "unable to expunge superblock")
+            } /* end if */
+            else
+                /* Free superblock */
+                sblock = (H5F_super_t *)H5FL_FREE(H5F_super_t, sblock);
+
+            /* Reset variables in file structure */
+            f->shared->sblock = NULL;
+            f->shared->super_addr = HADDR_UNDEF;
+        } /* end if */
+    } /* end if */
+
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5F_super_init() */
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5F_super_write
+ * Function:    H5F_super_dirty
  *
- * Purpose:     Writes the superblock for the file.
+ * Purpose:     Mark the file's superblock dirty
  *
- * Return:      Success:        SUCCEED
- *              Failure:        FAIL
+ * Return:      Success:        non-negative on success
+ *              Failure:        Negative
  *
- * Programmer:  Bill Wendling
- *              wendling@ncsa.uiuc.edu
- *              Sept 12, 2003
+ * Programmer:  Quincey Koziol
+ *              August 14, 2009
  *
  *-------------------------------------------------------------------------
  */
 herr_t
-H5F_super_write(H5F_t *f, hid_t dxpl_id)
+H5F_super_dirty(H5F_t *f)
 {
-    H5P_genplist_t *plist;                      /* File creation property list */
-    uint8_t         buf[H5F_MAX_SUPERBLOCK_SIZE + H5F_MAX_DRVINFOBLOCK_SIZE];  /* Superblock & driver info blockencoding buffer */
-    uint8_t        *p;                          /* Ptr into encoding buffer */
-    haddr_t         rel_eoa;                    /* Relative EOA for file */
-    size_t          superblock_size;            /* Size of superblock, in bytes */
-    size_t          driver_size;                /* Size of driver info block (bytes)*/
-    unsigned        super_vers;                 /* Superblock version              */
-    herr_t          ret_value = SUCCEED;
-
-    FUNC_ENTER_NOAPI(H5F_super_write, FAIL)
-
-    /* Get the shared file creation property list */
-    if(NULL == (plist = (H5P_genplist_t *)H5I_object(f->shared->fcpl_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list")
-
-    /* Grab values from property list */
-    if(H5P_get(plist, H5F_CRT_SUPER_VERS_NAME, &super_vers) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get superblock version")
-
-    /* Encode the common portion of the file superblock for all versions */
-    p = buf;
-    HDmemcpy(p, H5F_SIGNATURE, (size_t)H5F_SIGNATURE_LEN);
-    p += H5F_SIGNATURE_LEN;
-    *p++ = (uint8_t)super_vers;
-
-    /* Check for older version of superblock format */
-    if(super_vers < HDF5_SUPERBLOCK_VERSION_2) {
-        *p++ = (uint8_t)HDF5_FREESPACE_VERSION;     /* (hard-wired) */
-        *p++ = (uint8_t)HDF5_OBJECTDIR_VERSION;     /* (hard-wired) */
-        *p++ = 0;   /* reserved*/
-
-        *p++ = (uint8_t)HDF5_SHAREDHEADER_VERSION;  /* (hard-wired) */
-        HDassert(H5F_SIZEOF_ADDR(f) <= 255);
-        *p++ = (uint8_t)H5F_SIZEOF_ADDR(f);
-        HDassert(H5F_SIZEOF_SIZE(f) <= 255);
-        *p++ = (uint8_t)H5F_SIZEOF_SIZE(f);
-        *p++ = 0;   /* reserved */
-
-        UINT16ENCODE(p, f->shared->sym_leaf_k);
-        UINT16ENCODE(p, f->shared->btree_k[H5B_SNODE_ID]);
-        UINT32ENCODE(p, (uint32_t)f->shared->status_flags);
-
-        /*
-         * Versions of the superblock >0 have the indexed storage B-tree
-         * internal 'K' value stored
-         */
-        if(super_vers > HDF5_SUPERBLOCK_VERSION_DEF) {
-            UINT16ENCODE(p, f->shared->btree_k[H5B_CHUNK_ID]);
-            *p++ = 0;   /*reserved */
-            *p++ = 0;   /*reserved */
-        } /* end if */
-
-        H5F_addr_encode(f, &p, f->shared->base_addr);
-        H5F_addr_encode(f, &p, f->shared->extension_addr);
-        rel_eoa = H5FD_get_eoa(f->shared->lf, H5FD_MEM_SUPER);
-        H5F_addr_encode(f, &p, (rel_eoa + f->shared->base_addr));
-        H5F_addr_encode(f, &p, f->shared->driver_addr);
-
-        /* Encode the root group object entry, including the cached stab info */
-        if(H5G_root_ent_encode(f, &p) < 0)
-            HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to encode root group information")
-
-        /* Encode the driver information block. */
-        H5_ASSIGN_OVERFLOW(driver_size, H5FD_sb_size(f->shared->lf), hsize_t, size_t);
-
-        /* Checking whether driver block address is defined here is to handle backward
-         * compatibility.  If the file was created with v1.6 library or earlier and no
-         * driver info block was written in the superblock, we don't write it either even
-         * though there's some driver info.  Otherwise, the driver block extended will
-         * overwrite the (meta)data right after the superblock. This situation happens to
-         * the family driver particularly.  SLU - 2009/3/24 
-         */
-        if(driver_size > 0 && H5F_addr_defined(f->shared->driver_addr)) {
-            char driver_name[9];    /* Name of driver, for driver info block */
-            uint8_t *dbuf = p;      /* Pointer to beginning of driver info */
-
-            /* Encode the driver information block */
-            *p++ = HDF5_DRIVERINFO_VERSION_0; /* Version */
-            *p++ = 0; /* reserved */
-            *p++ = 0; /* reserved */
-            *p++ = 0; /* reserved */
-
-            /* Driver info size, excluding header */
-            UINT32ENCODE(p, driver_size);
-
-            /* Encode driver-specific data */
-            if(H5FD_sb_encode(f->shared->lf, driver_name, dbuf + H5F_DRVINFOBLOCK_HDR_SIZE) < 0)
-                HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to encode driver information")
-
-            /* Store driver name (set in 'H5FD_sb_encode' call above) */
-            HDmemcpy(p, driver_name, (size_t)8);
-
-            /* Advance buffer pointer past name & variable-sized portion of driver info */
-            /* (for later use in computing the superblock size) */
-            p += 8 + driver_size;
-        } /* end if */
-    } /* end if */
-    else {
-        uint32_t        chksum;                 /* Checksum temporary variable      */
-        H5O_loc_t       *root_oloc;             /* Pointer to root group's object location */
-
-        /* Size of file addresses & offsets, and status flags */
-        HDassert(H5F_SIZEOF_ADDR(f) <= 255);
-        *p++ = (uint8_t)H5F_SIZEOF_ADDR(f);
-        HDassert(H5F_SIZEOF_SIZE(f) <= 255);
-        *p++ = (uint8_t)H5F_SIZEOF_SIZE(f);
-        *p++ = f->shared->status_flags;
-
-        /* Base, superblock extension & end of file addresses */
-        H5F_addr_encode(f, &p, f->shared->base_addr);
-        H5F_addr_encode(f, &p, f->shared->extension_addr);
-        rel_eoa = H5FD_get_eoa(f->shared->lf, H5FD_MEM_SUPER);
-        H5F_addr_encode(f, &p, (rel_eoa + f->shared->base_addr));
-
-        /* Retrieve information for root group */
-        if(NULL == (root_oloc = H5G_oloc(f->shared->root_grp)))
-            HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to retrieve root group information")
-
-        /* Encode address of root group's object header */
-        H5F_addr_encode(f, &p, root_oloc->addr);
-
-        /* Compute superblock checksum */
-        chksum = H5_checksum_metadata(buf, (H5F_SUPERBLOCK_SIZE(super_vers, f) - H5F_SIZEOF_CHKSUM), 0);
-
-        /* Superblock checksum */
-        UINT32ENCODE(p, chksum);
-
-        /* Sanity check */
-        HDassert((size_t)(p - buf) == H5F_SUPERBLOCK_SIZE(super_vers, f));
-    } /* end else */
-
-    /* Retrieve the total size of the superblock info */
-    H5_ASSIGN_OVERFLOW(superblock_size, (p - buf), int, size_t);
-
-    /* Double check we didn't overrun the block (unlikely) */
-    HDassert(superblock_size <= sizeof(buf));
-
-    /* Write superblock (always at relative offset 0) */
-    if(H5FD_write(f->shared->lf, dxpl_id, H5FD_MEM_SUPER, (haddr_t)0, superblock_size, buf) < 0)
-        HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "unable to write superblock")
-
-    /* Check for newer version of superblock format & superblock extension */
-    if(super_vers >= HDF5_SUPERBLOCK_VERSION_2 && H5F_addr_defined(f->shared->extension_addr)) {
-        /* Check for driver info message */
-        H5_ASSIGN_OVERFLOW(driver_size, H5FD_sb_size(f->shared->lf), hsize_t, size_t);
-        if(driver_size > 0) {
-            H5O_drvinfo_t drvinfo;      /* Driver info */
-            uint8_t dbuf[H5F_MAX_DRVINFOBLOCK_SIZE];  /* Driver info block encoding buffer */
+    herr_t ret_value = SUCCEED;         /* Return value */
 
-            /* Sanity check */
-            HDassert(driver_size <= H5F_MAX_DRVINFOBLOCK_SIZE);
+    FUNC_ENTER_NOAPI(H5F_super_dirty, FAIL)
 
-            /* Encode driver-specific data */
-            if(H5FD_sb_encode(f->shared->lf, drvinfo.name, dbuf) < 0)
-                HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to encode driver information")
+    /* Sanity check */
+    HDassert(f);
+    HDassert(f->shared);
+    HDassert(f->shared->sblock);
 
-            /* Write driver info information to the superblock extension */
-            drvinfo.len = driver_size;
-            drvinfo.buf = dbuf;
-	    if(H5F_super_ext_write_msg(f, dxpl_id, &drvinfo, H5O_DRVINFO_ID, FALSE) < 0)
-                HGOTO_ERROR(H5E_FILE, H5E_WRITEERROR, FAIL, "unable to update driver info header message")
-        } /* end if */
-    } /* end if */
+    /* Mark superblock dirty in cache, so change to EOA will get encoded */
+    if(H5AC_mark_pinned_or_protected_entry_dirty(f, f->shared->sblock) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTMARKDIRTY, FAIL, "unable to mark superblock as dirty")
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5F_super_write() */
+} /* H5F_super_dirty() */
 
 
 /*-------------------------------------------------------------------------
@@ -1143,6 +638,7 @@ done:
  *
  * Programmer:  Vailin Choi
  *              July 11, 2007
+ *
  *-------------------------------------------------------------------------
  */
 herr_t
@@ -1154,34 +650,23 @@ H5F_super_size(H5F_t *f, hid_t dxpl_id, hsize_t *super_size, hsize_t *super_ext_
 
     /* Sanity check */
     HDassert(f);
+    HDassert(f->shared);
+    HDassert(f->shared->sblock);
 
     /* Set the superblock size */
-    if(super_size) {
-        H5P_genplist_t *plist;           	/* File creation property list */
-        unsigned        super_vers;       	/* Superblock version          */
-
-        /* Get the shared file creation property list */
-        if(NULL == (plist = (H5P_genplist_t *)H5I_object(f->shared->fcpl_id)))
-            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list")
-
-        /* Grab values from property list */
-        if(H5P_get(plist, H5F_CRT_SUPER_VERS_NAME, &super_vers) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get superblock version")
-
-        /* Set the superblock size */
-	*super_size = H5F_SUPERBLOCK_SIZE(super_vers, f);
-    } /* end if */
+    if(super_size)
+	*super_size = H5F_SUPERBLOCK_SIZE(f->shared->sblock->super_vers, f);
 
     /* Set the superblock extension size */
     if(super_ext_size) {
-        if(H5F_addr_defined(f->shared->extension_addr)) {
+        if(H5F_addr_defined(f->shared->sblock->ext_addr)) {
             H5O_loc_t ext_loc;                  /* "Object location" for superblock extension */
             H5O_info_t oinfo;                   /* Object info for superblock extension */
 
             /* Set up "fake" object location for superblock extension */
             H5O_loc_reset(&ext_loc);
             ext_loc.file = f;
-            ext_loc.addr = f->shared->extension_addr;
+            ext_loc.addr = f->shared->sblock->ext_addr;
 
             /* Get object header info for superblock extension */
             if(H5O_get_info(&ext_loc, dxpl_id, FALSE, &oinfo) < 0)
@@ -1211,24 +696,31 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
+herr_t
 H5F_super_ext_write_msg(H5F_t *f, hid_t dxpl_id, void *mesg, unsigned id, hbool_t may_create)
 {
+    hbool_t     sblock_dirty = FALSE;   /* Whether superblock was dirtied */
     H5O_loc_t 	ext_loc; 	/* "Object location" for superblock extension */
     htri_t 	status;       	/* Indicate whether the message exists or not */
     herr_t 	ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT(H5F_super_ext_write_msg)
 
+    /* Sanity checks */
+    HDassert(f);
+    HDassert(f->shared);
+    HDassert(f->shared->sblock);
+
     /* Open/create the superblock extension object header */
-    if(H5F_addr_defined(f->shared->extension_addr)) {
-	if(H5F_super_ext_open(f, &ext_loc) < 0)
+    if(H5F_addr_defined(f->shared->sblock->ext_addr)) {
+	if(H5F_super_ext_open(f, f->shared->sblock->ext_addr, &ext_loc) < 0)
 	    HGOTO_ERROR(H5E_FILE, H5E_CANTOPENOBJ, FAIL, "unable to open file's superblock extension")
     } /* end if */
     else {
         HDassert(may_create);
 	if(H5F_super_ext_create(f, dxpl_id, &ext_loc) < 0)
 	    HGOTO_ERROR(H5E_FILE, H5E_CANTCREATE, FAIL, "unable to create file's superblock extension")
+        sblock_dirty = TRUE;
     } /* end else */
     HDassert(H5F_addr_defined(ext_loc.addr));
 
@@ -1259,6 +751,11 @@ H5F_super_ext_write_msg(H5F_t *f, hid_t dxpl_id, void *mesg, unsigned id, hbool_
 	HGOTO_ERROR(H5E_FILE, H5E_CANTRELEASE, FAIL, "unable to close file's superblock extension")
 
 done:
+    /* Mark superblock dirty in cache, if necessary */
+    if(sblock_dirty)
+        if(H5AC_mark_pinned_or_protected_entry_dirty(f, f->shared->sblock) < 0)
+            HDONE_ERROR(H5E_FILE, H5E_CANTMARKDIRTY, FAIL, "unable to mark superblock as dirty")
+
     FUNC_LEAVE_NOAPI(ret_value)
 } /* H5F_super_ext_write_msg() */
 
diff --git a/src/H5Fsuper_cache.c b/src/H5Fsuper_cache.c
new file mode 100644
index 0000000..7df8f31
--- /dev/null
+++ b/src/H5Fsuper_cache.c
@@ -0,0 +1,854 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by The HDF Group.                                               *
+ * Copyright by the Board of Trustees of the University of Illinois.         *
+ * All rights reserved.                                                      *
+ *                                                                           *
+ * This file is part of HDF5.  The full HDF5 copyright notice, including     *
+ * terms governing use, modification, and redistribution, is contained in    *
+ * the files COPYING and Copyright.html.  COPYING can be found at the root   *
+ * of the source code distribution tree; Copyright.html can be found at the  *
+ * root level of an installed copy of the electronic HDF5 document set and   *
+ * is linked from the top-level documents page.  It can also be found at     *
+ * http://hdfgroup.org/HDF5/doc/Copyright.html.  If you do not have          *
+ * access to either file, you may request a copy from help@hdfgroup.org.     *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/****************/
+/* Module Setup */
+/****************/
+
+#define H5F_PACKAGE		/*suppress error about including H5Fpkg	  */
+#define H5G_PACKAGE		/*suppress error about including H5Gpkg	  */
+
+
+/***********/
+/* Headers */
+/***********/
+#include "H5private.h"		/* Generic Functions			*/
+#include "H5Eprivate.h"		/* Error handling		  	*/
+#include "H5Fpkg.h"             /* File access				*/
+#include "H5FDprivate.h"	/* File drivers				*/
+#include "H5FLprivate.h"        /* Free Lists                           */
+#include "H5Gpkg.h"		/* Groups		  		*/
+#include "H5Iprivate.h"		/* IDs			  		*/
+#include "H5MMprivate.h"        /* Memory management                    */
+#include "H5Pprivate.h"		/* Property lists			*/
+#include "H5SMprivate.h"        /* Shared Object Header Messages        */
+
+
+/****************/
+/* Local Macros */
+/****************/
+
+/* Maximum size of super-block buffers */
+#define H5F_MAX_SUPERBLOCK_SIZE  134
+
+
+/******************/
+/* Local Typedefs */
+/******************/
+
+
+/********************/
+/* Package Typedefs */
+/********************/
+
+
+/********************/
+/* Local Prototypes */
+/********************/
+
+/* Metadata cache (H5AC) callbacks */
+static H5F_super_t *H5F_sblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void *udata1, void *udata2);
+static herr_t H5F_sblock_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5F_super_t *sblock);
+static herr_t H5F_sblock_dest(H5F_t *f, H5F_super_t * sblock);
+static herr_t H5F_sblock_clear(H5F_t *f, H5F_super_t *sblock, hbool_t destroy);
+static herr_t H5F_sblock_size(const H5F_t *f, const H5F_super_t *sblock, size_t *size_ptr);
+
+
+/*********************/
+/* Package Variables */
+/*********************/
+
+/* H5F inherits cache-like properties from H5AC */
+const H5AC_class_t H5AC_SUPERBLOCK[1] = {{
+    H5AC_SUPERBLOCK_ID,
+    (H5AC_load_func_t)H5F_sblock_load,
+    (H5AC_flush_func_t)H5F_sblock_flush,
+    (H5AC_dest_func_t)H5F_sblock_dest,
+    (H5AC_clear_func_t)H5F_sblock_clear,
+    (H5AC_notify_func_t)NULL,
+    (H5AC_size_func_t)H5F_sblock_size,
+}};
+
+/*****************************/
+/* Library Private Variables */
+/*****************************/
+
+/* Declare extern the free list to manage the H5F_super_t struct */
+H5FL_EXTERN(H5F_super_t);
+
+
+/*******************/
+/* Local Variables */
+/*******************/
+
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5F_sblock_load
+ *
+ * Purpose:     Loads the superblock from the file, and deserializes
+ *              its information into the H5F_super_t structure.
+ *
+ * Return:      Success:        SUCCEED
+ *              Failure:        NULL
+ *
+ * Programmer:  Mike McGreevy
+ *              mamcgree@hdfgroup.org
+ *              April 8, 2009
+ *
+ *-------------------------------------------------------------------------
+ */
+static H5F_super_t *
+H5F_sblock_load(H5F_t *f, hid_t dxpl_id, haddr_t UNUSED addr, const void UNUSED *udata1, void *udata2/*out*/)
+{
+    H5F_super_t        *sblock = NULL;      /* File's superblock */
+    uint8_t             sbuf[H5F_MAX_SUPERBLOCK_SIZE];     /* Buffer for superblock */
+    H5P_genplist_t     *c_plist;            /* File creation property list  */
+    H5F_file_t         *shared;             /* shared part of `file'        */
+    H5FD_t             *lf;                 /* file driver part of `shared' */
+    haddr_t             stored_eoa;         /*relative end-of-addr in file  */
+    haddr_t             eof;                /*end of file address           */
+    size_t              sizeof_addr;        /* Size of offsets in the file (in bytes) */
+    size_t              sizeof_size;        /* Size of lengths in the file (in bytes) */
+    const size_t        fixed_size = H5F_SUPERBLOCK_FIXED_SIZE; /*fixed sizeof superblock   */
+    size_t              variable_size;      /*variable sizeof superblock    */
+    uint8_t            *p;                  /* Temporary pointer into encoding buffer */
+    unsigned            super_vers;         /* Superblock version          */
+    hbool_t            *dirtied = (hbool_t *)udata2;  /* Set up dirtied out value */
+    H5F_super_t        *ret_value;          /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT(H5F_sblock_load)
+
+    /* Short cuts */
+    shared = f->shared;
+    lf = shared->lf;
+
+    /* Get the shared file creation property list */
+    if(NULL == (c_plist = (H5P_genplist_t *)H5I_object(shared->fcpl_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "can't get property list")
+
+    /* Allocate space for the superblock */
+    if(NULL == (sblock = H5FL_CALLOC(H5F_super_t)))
+        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
+    
+    /* Read fixed-size portion of the superblock */
+    p = sbuf;
+    if(H5FD_set_eoa(lf, H5FD_MEM_SUPER, f->shared->super_addr + fixed_size) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, NULL, "set end of space allocation request failed")
+    if(H5FD_read(lf, dxpl_id, H5FD_MEM_SUPER, f->shared->super_addr, fixed_size, p) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_READERROR, NULL, "unable to read superblock")
+
+    /* Skip over signature (already checked when locating the superblock) */
+    p += H5F_SIGNATURE_LEN;
+
+    /* Superblock version */
+    super_vers = *p++;
+    if(super_vers > HDF5_SUPERBLOCK_VERSION_LATEST)
+        HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad superblock version number")
+    if(H5P_set(c_plist, H5F_CRT_SUPER_VERS_NAME, &super_vers) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "unable to set superblock version")
+
+    /* Record the superblock version */
+    sblock->super_vers = super_vers;
+
+    /* Sanity check */
+    HDassert(((size_t)(p - sbuf)) == fixed_size);
+
+    /* Determine the size of the variable-length part of the superblock */
+    variable_size = H5F_SUPERBLOCK_VARLEN_SIZE(super_vers, f);
+    HDassert(variable_size > 0);
+    HDassert(fixed_size + variable_size <= sizeof(sbuf));
+
+    /* Read in variable-sized portion of superblock */
+    if(H5FD_set_eoa(lf, H5FD_MEM_SUPER, f->shared->super_addr + fixed_size + variable_size) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, NULL, "set end of space allocation request failed")
+    if(H5FD_read(lf, dxpl_id, H5FD_MEM_SUPER, f->shared->super_addr + fixed_size, variable_size, p) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "unable to read superblock")
+    /* Check for older version of superblock format */
+    if(super_vers < HDF5_SUPERBLOCK_VERSION_2) {
+        uint32_t	status_flags;	    /* File status flags	   */
+        unsigned        btree_k[H5B_NUM_BTREE_ID];  /* B-tree internal node 'K' values */
+        unsigned        sym_leaf_k;         /* Symbol table leaf node's 'K' value */
+
+        /* Freespace version (hard-wired) */
+        if(HDF5_FREESPACE_VERSION != *p++)
+            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad free space version number")
+
+        /* Root group version number (hard-wired) */
+        if(HDF5_OBJECTDIR_VERSION != *p++)
+            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad object directory version number")
+
+        /* Skip over reserved byte */
+        p++;
+
+        /* Shared header version number (hard-wired) */
+        if(HDF5_SHAREDHEADER_VERSION != *p++)
+            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad shared-header format version number")
+
+        /* Size of file addresses */
+        sizeof_addr = *p++;
+        if(sizeof_addr != 2 && sizeof_addr != 4 &&
+                sizeof_addr != 8 && sizeof_addr != 16 && sizeof_addr != 32)
+            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad byte number in an address")
+        if(H5P_set(c_plist, H5F_CRT_ADDR_BYTE_NUM_NAME, &sizeof_addr) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "unable to set byte number in an address")
+        shared->sizeof_addr = sizeof_addr;  /* Keep a local copy also */
+
+        /* Size of file sizes */
+        sizeof_size = *p++;
+        if(sizeof_size != 2 && sizeof_size != 4 &&
+                sizeof_size != 8 && sizeof_size != 16 && sizeof_size != 32)
+            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad byte number for object size")
+        if(H5P_set(c_plist, H5F_CRT_OBJ_BYTE_NUM_NAME, &sizeof_size) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "unable to set byte number for object size")
+        shared->sizeof_size = sizeof_size;  /* Keep a local copy also */
+
+        /* Skip over reserved byte */
+        p++;
+
+        /* Various B-tree sizes */
+        UINT16DECODE(p, sym_leaf_k);
+        if(sym_leaf_k == 0)
+            HGOTO_ERROR(H5E_FILE, H5E_BADRANGE, NULL, "bad symbol table leaf node 1/2 rank")
+        if(H5P_set(c_plist, H5F_CRT_SYM_LEAF_NAME, &sym_leaf_k) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "unable to set rank for symbol table leaf nodes")
+        sblock->sym_leaf_k = sym_leaf_k;    /* Keep a local copy also */
+
+        /* Need 'get' call to set other array values */
+        if(H5P_get(c_plist, H5F_CRT_BTREE_RANK_NAME, btree_k) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "unable to get rank for btree internal nodes")
+        UINT16DECODE(p, btree_k[H5B_SNODE_ID]);
+        if(btree_k[H5B_SNODE_ID] == 0)
+            HGOTO_ERROR(H5E_FILE, H5E_BADRANGE, NULL, "bad 1/2 rank for btree internal nodes")
+        /*
+         * Delay setting the value in the property list until we've checked
+         * for the indexed storage B-tree internal 'K' value later.
+         */
+
+        /* File status flags (not really used yet) */
+        UINT32DECODE(p, status_flags);
+        HDassert(status_flags <= 255);
+        sblock->status_flags = (uint8_t)status_flags;
+        if(sblock->status_flags & ~H5F_SUPER_ALL_FLAGS)
+            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad flag value for superblock")
+
+        /*
+         * If the superblock version # is greater than 0, read in the indexed
+         * storage B-tree internal 'K' value
+         */
+        if(super_vers > HDF5_SUPERBLOCK_VERSION_DEF) {
+            UINT16DECODE(p, btree_k[H5B_CHUNK_ID]);
+            /* Reserved bytes are present only in version 1 */
+            if(super_vers == HDF5_SUPERBLOCK_VERSION_1)
+                p += 2;   /* reserved */
+        } /* end if */
+        else
+            btree_k[H5B_CHUNK_ID] = HDF5_BTREE_CHUNK_IK_DEF;
+
+        /* Set the B-tree internal node values, etc */
+        if(H5P_set(c_plist, H5F_CRT_BTREE_RANK_NAME, btree_k) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "unable to set rank for btree internal nodes")
+        HDmemcpy(sblock->btree_k, btree_k, sizeof(unsigned) * (size_t)H5B_NUM_BTREE_ID);    /* Keep a local copy also */
+
+        /* Remainder of "variable-sized" portion of superblock */
+        H5F_addr_decode(f, (const uint8_t **)&p, &sblock->base_addr/*out*/);
+        H5F_addr_decode(f, (const uint8_t **)&p, &sblock->ext_addr/*out*/);
+        H5F_addr_decode(f, (const uint8_t **)&p, &stored_eoa/*out*/);
+        H5F_addr_decode(f, (const uint8_t **)&p, &sblock->driver_addr/*out*/);
+
+        /* Allocate space for the root group symbol table entry */
+        HDassert(!sblock->root_ent);
+        if(NULL == (sblock->root_ent = (H5G_entry_t *)H5MM_calloc(sizeof(H5G_entry_t))))
+            HGOTO_ERROR(H5E_FILE, H5E_CANTALLOC, NULL, "can't allocate space for root group symbol table entry")
+
+        /* decode the root group symbol table entry */
+        if(H5G_ent_decode(f, (const uint8_t **)&p, sblock->root_ent) < 0)
+            HGOTO_ERROR(H5E_FILE, H5E_CANTDECODE, NULL, "can't decode root group symbol table entry")
+
+        /* Set the root group address to the correct value */
+        sblock->root_addr = sblock->root_ent->header;
+
+        /*
+         * Check if superblock address is different from base address and
+         * adjust base address and "end of address" address if so.
+         */
+        if(!H5F_addr_eq(f->shared->super_addr, sblock->base_addr)) {
+            /* Check if the superblock moved earlier in the file */
+            if(H5F_addr_lt(f->shared->super_addr, sblock->base_addr))
+                stored_eoa -= (sblock->base_addr - f->shared->super_addr);
+            else
+                /* The superblock moved later in the file */
+                stored_eoa += (f->shared->super_addr - sblock->base_addr);
+
+            sblock->base_addr = f->shared->super_addr;
+        } /* end if */
+
+        /* Set the base address for the file in the VFD now, after adjusting
+         *  space for possible offsets of the HDF5 data in the file.
+         */
+        if(H5FD_set_base_addr(lf, sblock->base_addr) < 0)
+            HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, NULL, "failed to set base address for file driver")
+
+        /* This step is for h5repart tool only. If user wants to change file driver
+         *  from family to sec2 while using h5repart, set the driver address to
+         *  undefined to let the library ignore the family driver information saved
+         *  in the superblock.
+         */
+        if(H5F_HAS_FEATURE(f, H5FD_FEAT_IGNORE_DRVRINFO)) {
+            /* Eliminate the driver info */
+            sblock->driver_addr = HADDR_UNDEF;
+
+            /* Indicate that the superblock should be marked dirty */
+            *dirtied = TRUE;
+        } /* end if */
+
+        /* Decode the optional driver information block */
+        if(H5F_addr_defined(sblock->driver_addr)) {
+            uint8_t dbuf[H5F_MAX_DRVINFOBLOCK_SIZE];     /* Buffer for driver info block */
+            char drv_name[9];       /* Name of driver */
+            unsigned drv_vers;      /* Version of driver info block */
+            size_t drv_variable_size; /* Size of variable-length portion of driver info block, in bytes */
+
+            /* Read in fixed-sized portion of driver info block */
+            p = dbuf;
+            if(H5FD_set_eoa(lf, H5FD_MEM_SUPER, sblock->driver_addr + H5F_DRVINFOBLOCK_HDR_SIZE) < 0)
+                HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, NULL, "set end of space allocation request failed")
+            if(H5FD_read(lf, dxpl_id, H5FD_MEM_SUPER, sblock->driver_addr, (size_t)H5F_DRVINFOBLOCK_HDR_SIZE, p) < 0)
+                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "unable to read driver information block")
+
+            /* Version number */
+            drv_vers = *p++;
+            if(drv_vers != HDF5_DRIVERINFO_VERSION_0)
+                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "bad driver information block version number")
+
+            p += 3; /* reserved bytes */
+
+            /* Driver info size */
+            UINT32DECODE(p, drv_variable_size);
+
+            /* Sanity check */
+            HDassert(H5F_DRVINFOBLOCK_HDR_SIZE + drv_variable_size <= sizeof(dbuf));
+
+            /* Driver name and/or version */
+            HDstrncpy(drv_name, (const char *)p, (size_t)8);
+            drv_name[8] = '\0';
+            p += 8; /* advance past name/version */
+
+            /* Check if driver matches driver information saved. Unfortunately, we can't push this
+             * function to each specific driver because we're checking if the driver is correct.
+             */
+            if(!HDstrncmp(drv_name, "NCSAfami", (size_t)8) && HDstrcmp(lf->cls->name, "family"))
+                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "family driver should be used")
+            if(!HDstrncmp(drv_name, "NCSAmult", (size_t)8) && HDstrcmp(lf->cls->name, "multi"))
+                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "multi driver should be used")
+
+            /* Read in variable-sized portion of driver info block */
+            if(H5FD_set_eoa(lf, H5FD_MEM_SUPER, sblock->driver_addr + H5F_DRVINFOBLOCK_HDR_SIZE + drv_variable_size) < 0)
+                HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, NULL, "set end of space allocation request failed")
+            if(H5FD_read(lf, dxpl_id, H5FD_MEM_SUPER, sblock->driver_addr + H5F_DRVINFOBLOCK_HDR_SIZE, drv_variable_size, p) < 0)
+                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "unable to read file driver information")
+
+            /* Decode driver information */
+            if(H5FD_sb_decode(lf, drv_name, p) < 0)
+                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "unable to decode driver information")
+        } /* end if */
+    } /* end if */
+    else {
+        uint32_t computed_chksum;       /* Computed checksum  */
+        uint32_t read_chksum;           /* Checksum read from file  */
+
+        /* Size of file addresses */
+        sizeof_addr = *p++;
+        if(sizeof_addr != 2 && sizeof_addr != 4 &&
+                sizeof_addr != 8 && sizeof_addr != 16 && sizeof_addr != 32)
+            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad byte number in an address")
+        if(H5P_set(c_plist, H5F_CRT_ADDR_BYTE_NUM_NAME, &sizeof_addr) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "unable to set byte number in an address")
+        shared->sizeof_addr = sizeof_addr;  /* Keep a local copy also */
+
+        /* Size of file sizes */
+        sizeof_size = *p++;
+        if(sizeof_size != 2 && sizeof_size != 4 &&
+                sizeof_size != 8 && sizeof_size != 16 && sizeof_size != 32)
+            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad byte number for object size")
+        if(H5P_set(c_plist, H5F_CRT_OBJ_BYTE_NUM_NAME, &sizeof_size) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "unable to set byte number for object size")
+        shared->sizeof_size = sizeof_size;  /* Keep a local copy also */
+
+        /* File status flags (not really used yet) */
+        sblock->status_flags = *p++;
+        if(sblock->status_flags & ~H5F_SUPER_ALL_FLAGS)
+            HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad flag value for superblock")
+
+        /* Base, superblock extension, end of file & root group object header addresses */
+        H5F_addr_decode(f, (const uint8_t **)&p, &sblock->base_addr/*out*/);
+        H5F_addr_decode(f, (const uint8_t **)&p, &sblock->ext_addr/*out*/);
+        H5F_addr_decode(f, (const uint8_t **)&p, &stored_eoa/*out*/);
+        H5F_addr_decode(f, (const uint8_t **)&p, &sblock->root_addr/*out*/);
+
+        /* Compute checksum for superblock */
+        computed_chksum = H5_checksum_metadata(sbuf, (size_t)(p - sbuf), 0);
+
+        /* Decode checksum */
+        UINT32DECODE(p, read_chksum);
+
+        /* Verify correct checksum */
+        if(read_chksum != computed_chksum)
+            HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "bad checksum on driver information block")
+
+        /*
+         * Check if superblock address is different from base address and
+         * adjust base address and "end of address" address if so.
+         */
+        if(!H5F_addr_eq(f->shared->super_addr, sblock->base_addr)) {
+            /* Check if the superblock moved earlier in the file */
+            if(H5F_addr_lt(f->shared->super_addr, sblock->base_addr))
+                stored_eoa -= (sblock->base_addr - f->shared->super_addr);
+            else
+                /* The superblock moved later in the file */
+                stored_eoa += (f->shared->super_addr - sblock->base_addr);
+
+            sblock->base_addr = f->shared->super_addr;
+        } /* end if */
+
+        /* Set the base address for the file in the VFD now, after adjusting
+         *  space for possible offsets of the HDF5 data in the file.
+         */
+        if(H5FD_set_base_addr(lf, sblock->base_addr) < 0)
+            HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, NULL, "failed to set base address for file driver")
+
+        /* Get the B-tree internal node values, etc */
+        if(H5P_get(c_plist, H5F_CRT_BTREE_RANK_NAME, sblock->btree_k) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "unable to get rank for btree internal nodes")
+    } /* end else */
+
+    /*
+     * The user-defined data is the area of the file before the base
+     * address.
+     */
+    if(H5P_set(c_plist, H5F_CRT_USER_BLOCK_NAME, &sblock->base_addr) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "unable to set userblock size")
+
+    /*
+     * Make sure that the data is not truncated. One case where this is
+     * possible is if the first file of a family of files was opened
+     * individually.
+     */
+    if(HADDR_UNDEF == (eof = H5FD_get_eof(lf)))
+        HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "unable to determine file size")
+
+    /* (Account for the stored EOA being absolute offset -QAK) */
+    if((eof + sblock->base_addr) < stored_eoa)
+        HGOTO_ERROR(H5E_FILE, H5E_TRUNCATED, NULL, "truncated file")
+
+    /*
+     * Tell the file driver how much address space has already been
+     * allocated so that it knows how to allocate additional memory.
+     */
+    /* (Account for the stored EOA being absolute offset -NAF) */
+    if(H5FD_set_eoa(lf, H5FD_MEM_SUPER, stored_eoa - sblock->base_addr) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "unable to set end-of-address marker for file")
+
+    /* Read the file's superblock extension, if there is one. */
+    if(H5F_addr_defined(sblock->ext_addr)) {
+        H5O_loc_t ext_loc;      /* "Object location" for superblock extension */
+        H5O_btreek_t btreek;    /* v1 B-tree 'K' value message from superblock extension */
+        H5O_drvinfo_t drvinfo;  /* Driver info message from superblock extension */
+        htri_t status;          /* Status for message existing */
+
+        /* Sanity check - superblock extension should only be defined for
+         *      superblock version >= 2.
+         */
+        HDassert(super_vers >= HDF5_SUPERBLOCK_VERSION_2);
+
+        /* Check for superblock extension being located "outside" the stored
+         *      'eoa' value, which can occur with the split/multi VFD.
+         */
+        if(H5F_addr_gt(sblock->ext_addr, stored_eoa)) {
+            /* Set the 'eoa' for the object header memory type large enough
+             *  to give some room for a reasonably sized superblock extension.
+             *  (This is _rather_ a kludge -QAK)
+             */
+            if(H5FD_set_eoa(lf, H5FD_MEM_OHDR, (haddr_t)(sblock->ext_addr + 1024)) < 0)
+                HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "unable to set end-of-address marker for file")
+        } /* end if */
+
+        /* Open the superblock extension */
+	if(H5F_super_ext_open(f, sblock->ext_addr, &ext_loc) < 0)
+            HGOTO_ERROR(H5E_FILE, H5E_CANTOPENOBJ, NULL, "unable to open file's superblock extension")
+
+        /* Check for the extension having a 'driver info' message */
+        if((status = H5O_msg_exists(&ext_loc, H5O_DRVINFO_ID, dxpl_id)) < 0)
+            HGOTO_ERROR(H5E_FILE, H5E_CANTGET, NULL, "unable to read object header")
+        if(status) {
+            /* Check for ignoring the driver info for this file */
+            if(H5F_HAS_FEATURE(f, H5FD_FEAT_IGNORE_DRVRINFO)) {
+                /* Indicate that the superblock should be marked dirty */
+                *dirtied = TRUE;
+            } /* end if */
+            else {
+                /* Retrieve the 'driver info' structure */
+                if(NULL == H5O_msg_read(&ext_loc, H5O_DRVINFO_ID, &drvinfo, dxpl_id))
+                    HGOTO_ERROR(H5E_FILE, H5E_CANTGET, NULL, "driver info message not present")
+
+                /* Check if driver matches driver information saved. Unfortunately, we can't push this
+                 * function to each specific driver because we're checking if the driver is correct.
+                 */
+                if(!HDstrncmp(drvinfo.name, "NCSAfami", (size_t)8) && HDstrcmp(lf->cls->name, "family"))
+                    HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "family driver should be used")
+                if(!HDstrncmp(drvinfo.name, "NCSAmult", (size_t)8) && HDstrcmp(lf->cls->name, "multi"))
+                    HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "multi driver should be used")
+
+                /* Decode driver information */
+                if(H5FD_sb_decode(lf, drvinfo.name, drvinfo.buf) < 0)
+                    HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "unable to decode driver information")
+
+                /* Reset driver info message */
+                H5O_msg_reset(H5O_DRVINFO_ID, &drvinfo);
+            } /* end else */
+        } /* end if */
+
+        /* Read in the shared OH message information if there is any */
+        if(H5SM_get_info(&ext_loc, c_plist, dxpl_id) < 0)
+            HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "unable to read SOHM table information")
+
+        /* Check for the extension having a 'v1 B-tree "K"' message */
+        if((status = H5O_msg_exists(&ext_loc, H5O_BTREEK_ID, dxpl_id)) < 0)
+            HGOTO_ERROR(H5E_FILE, H5E_CANTGET, NULL, "unable to read object header")
+        if(status) {
+            /* Retrieve the 'v1 B-tree "K"' structure */
+            if(NULL == H5O_msg_read(&ext_loc, H5O_BTREEK_ID, &btreek, dxpl_id))
+                HGOTO_ERROR(H5E_FILE, H5E_CANTGET, NULL, "v1 B-tree 'K' info message not present")
+
+            /* Set non-default v1 B-tree 'K' value info from file */
+            sblock->btree_k[H5B_CHUNK_ID] = btreek.btree_k[H5B_CHUNK_ID];
+            sblock->btree_k[H5B_SNODE_ID] = btreek.btree_k[H5B_SNODE_ID];
+            sblock->sym_leaf_k = btreek.sym_leaf_k;
+
+            /* Set non-default v1 B-tree 'K' values in the property list */
+            if(H5P_set(c_plist, H5F_CRT_BTREE_RANK_NAME, btreek.btree_k) < 0)
+                HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "unable to set rank for btree internal nodes")
+            if(H5P_set(c_plist, H5F_CRT_SYM_LEAF_NAME, &btreek.sym_leaf_k) < 0)
+                HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "unable to set rank for symbol table leaf nodes")
+        } /* end if */
+        else {
+            /* No non-default v1 B-tree 'K' value info in file, use defaults */
+            sblock->btree_k[H5B_CHUNK_ID] = HDF5_BTREE_CHUNK_IK_DEF;
+            sblock->btree_k[H5B_SNODE_ID] = HDF5_BTREE_SNODE_IK_DEF;
+            sblock->sym_leaf_k = H5F_CRT_SYM_LEAF_DEF;
+        } /* end if */
+
+        /* Close superblock extension */
+	if(H5F_super_ext_close(f, &ext_loc) < 0)
+	    HGOTO_ERROR(H5E_FILE, H5E_CANTRELEASE, NULL, "unable to close file's superblock extension")
+    } /* end if */
+
+    /* Set return value */
+    ret_value = sblock;
+
+done:
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5F_sblock_load() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5F_sblock_flush
+ *
+ * Purpose:     Flushes the superblock.
+ *
+ * Return:      Success:        SUCCEED
+ *              Failure:        NULL
+ *
+ * Programmer:  Mike McGreevy
+ *              mamcgree@hdfgroup.org
+ *              April 8, 2009
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5F_sblock_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5F_super_t *sblock)
+{
+    herr_t          ret_value = SUCCEED;
+
+    FUNC_ENTER_NOAPI_NOINIT(H5F_sblock_flush)
+
+    /* check arguments */
+    HDassert(f);
+    HDassert(sblock);
+
+    if(sblock->cache_info.is_dirty) {
+        uint8_t         buf[H5F_MAX_SUPERBLOCK_SIZE + H5F_MAX_DRVINFOBLOCK_SIZE];  /* Superblock & driver info blockencoding buffer */
+        uint8_t        *p;                          /* Ptr into encoding buffer */
+        haddr_t         rel_eoa;                    /* Relative EOA for file */
+        size_t          superblock_size;            /* Size of superblock, in bytes */
+        size_t          driver_size;                /* Size of driver info block (bytes)*/
+
+        /* Encode the common portion of the file superblock for all versions */
+        p = buf;
+        HDmemcpy(p, H5F_SIGNATURE, (size_t)H5F_SIGNATURE_LEN);
+        p += H5F_SIGNATURE_LEN;
+        *p++ = (uint8_t)sblock->super_vers;
+    
+        /* Check for older version of superblock format */
+        if(sblock->super_vers < HDF5_SUPERBLOCK_VERSION_2) {
+            *p++ = (uint8_t)HDF5_FREESPACE_VERSION;     /* (hard-wired) */
+            *p++ = (uint8_t)HDF5_OBJECTDIR_VERSION;     /* (hard-wired) */
+            *p++ = 0;   /* reserved*/
+    
+            *p++ = (uint8_t)HDF5_SHAREDHEADER_VERSION;  /* (hard-wired) */
+            HDassert(H5F_SIZEOF_ADDR(f) <= 255);
+            *p++ = (uint8_t)H5F_SIZEOF_ADDR(f);
+            HDassert(H5F_SIZEOF_SIZE(f) <= 255);
+            *p++ = (uint8_t)H5F_SIZEOF_SIZE(f);
+            *p++ = 0;   /* reserved */
+    
+            UINT16ENCODE(p, sblock->sym_leaf_k);
+            UINT16ENCODE(p, sblock->btree_k[H5B_SNODE_ID]);
+            UINT32ENCODE(p, (uint32_t)sblock->status_flags);
+    
+            /*
+             * Versions of the superblock >0 have the indexed storage B-tree
+             * internal 'K' value stored
+             */
+            if(sblock->super_vers > HDF5_SUPERBLOCK_VERSION_DEF) {
+                UINT16ENCODE(p, sblock->btree_k[H5B_CHUNK_ID]);
+                *p++ = 0;   /*reserved */
+                *p++ = 0;   /*reserved */
+            } /* end if */
+    
+            H5F_addr_encode(f, &p, sblock->base_addr);
+            H5F_addr_encode(f, &p, sblock->ext_addr);
+            rel_eoa = H5FD_get_eoa(f->shared->lf, H5FD_MEM_SUPER);
+            H5F_addr_encode(f, &p, (rel_eoa + sblock->base_addr));
+            H5F_addr_encode(f, &p, sblock->driver_addr);
+            
+            /* Encode the root group object entry, including the cached stab info */
+            if(H5G_ent_encode(f, &p, sblock->root_ent) < 0)
+                HGOTO_ERROR(H5E_FILE, H5E_CANTENCODE, FAIL, "can't encode root group symbol table entry")
+    
+            /* Encode the driver information block. */
+            H5_ASSIGN_OVERFLOW(driver_size, H5FD_sb_size(f->shared->lf), hsize_t, size_t);
+    
+            /* Checking whether driver block address is defined here is to handle backward
+             * compatibility.  If the file was created with v1.6 library or earlier and no
+             * driver info block was written in the superblock, we don't write it either even
+             * though there's some driver info.  Otherwise, the driver block extended will
+             * overwrite the (meta)data right after the superblock. This situation happens to
+             * the family driver particularly.  SLU - 2009/3/24 
+             */
+            if(driver_size > 0 && H5F_addr_defined(sblock->driver_addr)) {
+                char driver_name[9];    /* Name of driver, for driver info block */
+                uint8_t *dbuf = p;      /* Pointer to beginning of driver info */
+    
+                /* Encode the driver information block */
+                *p++ = HDF5_DRIVERINFO_VERSION_0; /* Version */
+                *p++ = 0; /* reserved */
+                *p++ = 0; /* reserved */
+                *p++ = 0; /* reserved */
+    
+                /* Driver info size, excluding header */
+                UINT32ENCODE(p, driver_size);
+
+                /* Encode driver-specific data */
+                if(H5FD_sb_encode(f->shared->lf, driver_name, dbuf + H5F_DRVINFOBLOCK_HDR_SIZE) < 0)
+                    HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to encode driver information")
+
+                /* Store driver name (set in 'H5FD_sb_encode' call above) */
+                HDmemcpy(p, driver_name, (size_t)8);
+    
+                /* Advance buffer pointer past name & variable-sized portion of driver info */
+                /* (for later use in computing the superblock size) */
+                p += 8 + driver_size;
+            } /* end if */
+        } /* end if */
+        else {
+            uint32_t        chksum;                 /* Checksum temporary variable      */
+            H5O_loc_t       *root_oloc;             /* Pointer to root group's object location */
+    
+            /* Size of file addresses & offsets, and status flags */
+            HDassert(H5F_SIZEOF_ADDR(f) <= 255);
+            *p++ = (uint8_t)H5F_SIZEOF_ADDR(f);
+            HDassert(H5F_SIZEOF_SIZE(f) <= 255);
+            *p++ = (uint8_t)H5F_SIZEOF_SIZE(f);
+            *p++ = sblock->status_flags;
+    
+            /* Base, superblock extension & end of file addresses */
+            H5F_addr_encode(f, &p, sblock->base_addr);
+            H5F_addr_encode(f, &p, sblock->ext_addr);
+            rel_eoa = H5FD_get_eoa(f->shared->lf, H5FD_MEM_SUPER);
+            H5F_addr_encode(f, &p, (rel_eoa + sblock->base_addr));
+    
+            /* Retrieve information for root group */
+            if(NULL == (root_oloc = H5G_oloc(f->shared->root_grp)))
+                HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to retrieve root group information")
+    
+            /* Encode address of root group's object header */
+            H5F_addr_encode(f, &p, root_oloc->addr);
+    
+            /* Compute superblock checksum */
+            chksum = H5_checksum_metadata(buf, (H5F_SUPERBLOCK_SIZE(sblock->super_vers, f) - H5F_SIZEOF_CHKSUM), 0);
+    
+            /* Superblock checksum */
+            UINT32ENCODE(p, chksum);
+    
+            /* Sanity check */
+            HDassert((size_t)(p - buf) == H5F_SUPERBLOCK_SIZE(sblock->super_vers, f));
+        } /* end else */
+    
+        /* Retrieve the total size of the superblock info */
+        H5_ASSIGN_OVERFLOW(superblock_size, (p - buf), int, size_t);
+    
+        /* Double check we didn't overrun the block (unlikely) */
+        HDassert(superblock_size <= sizeof(buf));
+
+        /* Write superblock */
+        /* (always at relative address 0) */
+        if(H5FD_write(f->shared->lf, dxpl_id, H5FD_MEM_SUPER, (haddr_t)0, superblock_size, buf) < 0)
+            HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "unable to write superblock")
+    
+        /* Check for newer version of superblock format & superblock extension */
+        if(sblock->super_vers >= HDF5_SUPERBLOCK_VERSION_2 && H5F_addr_defined(sblock->ext_addr)) {
+            /* Check for ignoring the driver info for this file */
+            if(!H5F_HAS_FEATURE(f, H5FD_FEAT_IGNORE_DRVRINFO)) {
+                /* Check for driver info message */
+                H5_ASSIGN_OVERFLOW(driver_size, H5FD_sb_size(f->shared->lf), hsize_t, size_t);
+                if(driver_size > 0) {
+                    H5O_drvinfo_t drvinfo;      /* Driver info */
+                    uint8_t dbuf[H5F_MAX_DRVINFOBLOCK_SIZE];  /* Driver info block encoding buffer */
+        
+                    /* Sanity check */
+                    HDassert(driver_size <= H5F_MAX_DRVINFOBLOCK_SIZE);
+        
+                    /* Encode driver-specific data */
+                    if(H5FD_sb_encode(f->shared->lf, drvinfo.name, dbuf) < 0)
+                        HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to encode driver information")
+        
+                    /* Write driver info information to the superblock extension */
+                    drvinfo.len = driver_size;
+                    drvinfo.buf = dbuf;
+                    if(H5F_super_ext_write_msg(f, dxpl_id, &drvinfo, H5O_DRVINFO_ID, FALSE) < 0)
+                        HGOTO_ERROR(H5E_FILE, H5E_WRITEERROR, FAIL, "unable to update driver info header message")
+                } /* end if */
+            } /* end if */
+        } /* end if */
+
+        /* Reset the dirty flag.  */
+        sblock->cache_info.is_dirty = FALSE;
+    } /* end if */
+
+    if(destroy)
+        if(H5F_sblock_dest(f, sblock) < 0)
+            HGOTO_ERROR(H5E_FSPACE, H5E_CLOSEERROR, FAIL, "can't close superblock")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5F_sblock_flush() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5F_sblock_dest
+ *
+ * Purpose:     Frees memory used by the superblock.
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *
+ * Programmer:  Mike McGreevy
+ *              April 8, 2009
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5F_sblock_dest(H5F_t UNUSED *f, H5F_super_t* sblock)
+{
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5F_sblock_dest)
+
+    /* Sanity check */
+    HDassert(sblock);
+
+    /* Free root group symbol table entry, if any */
+    sblock->root_ent = (H5G_entry_t *)H5MM_xfree(sblock->root_ent);
+
+    /* Free superblock */
+    sblock = (H5F_super_t *)H5FL_FREE(H5F_super_t, sblock);
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5F_sblock_dest() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5F_sblock_clear
+ *
+ * Purpose:     Mark the superblock as no longer being dirty.
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *
+ * Programmer:  Mike McGreevy
+ *              April 8, 2009
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5F_sblock_clear(H5F_t *f, H5F_super_t *sblock, hbool_t destroy)
+{
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT(H5F_sblock_clear)
+
+    /*
+     * Check arguments.
+     */
+    HDassert(sblock);
+
+    /* Reset the dirty flag.  */
+    sblock->cache_info.is_dirty = FALSE;
+
+    if(destroy)
+        if(H5F_sblock_dest(f, sblock) < 0)
+            HGOTO_ERROR(H5E_FILE, H5E_CANTFREE, FAIL, "unable to delete superblock")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5F_sblock_clear() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5F_sblock_size
+ *
+ * Purpose:     Returns the size of the superblock encoded on disk.
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *
+ * Programmer:  Mike McGreevy
+ *              April 8, 2009
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5F_sblock_size(const H5F_t *f, const H5F_super_t *sblock, size_t *size_ptr)
+{
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5F_sblock_size)
+
+    /* check arguments */
+    HDassert(f);
+    HDassert(sblock);
+    HDassert(size_ptr);
+
+    /* Set size value */
+    *size_ptr = H5F_SUPERBLOCK_SIZE(sblock->super_vers, f);
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5F_sblock_size() */
+
diff --git a/src/H5Ftest.c b/src/H5Ftest.c
index 72fee96..e2ee606 100644
--- a/src/H5Ftest.c
+++ b/src/H5Ftest.c
@@ -146,7 +146,7 @@ H5F_check_cached_stab_test(hid_t file_id)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file")
 
     /* Verify the cached stab info */
-    if(H5G_verify_cached_stab_test(H5G_oloc(file->shared->root_grp), file->shared->root_ent) < 0)
+    if(H5G_verify_cached_stab_test(H5G_oloc(file->shared->root_grp), file->shared->sblock->root_ent) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTGET, FAIL, "unable to verify cached symbol table info")
 
 done:
diff --git a/src/H5Gent.c b/src/H5Gent.c
index 7a9e9e5..65f302c 100644
--- a/src/H5Gent.c
+++ b/src/H5Gent.c
@@ -28,15 +28,10 @@
 #include "H5FLprivate.h"	/* Free Lists                           */
 #include "H5Gpkg.h"		/* Groups		  		*/
 #include "H5HLprivate.h"	/* Local Heaps				*/
-#include "H5Iprivate.h"		/* IDs			  		*/
-#include "H5MMprivate.h"        /* Memory Management                    */
 
 /* Private macros */
 
 /* Private prototypes */
-static herr_t H5G_ent_encode(H5F_t *f, uint8_t **pp, const H5G_entry_t *ent);
-static herr_t H5G_ent_decode(H5F_t *f, const uint8_t **pp,
-			      H5G_entry_t *ent/*out*/);
 
 /* Declare extern the PQ free list for the wrapped strings */
 H5FL_BLK_EXTERN(str_buf);
@@ -48,9 +43,6 @@ H5FL_BLK_EXTERN(str_buf);
  * Purpose:     Same as H5G_ent_decode() except it does it for an array of
  *              symbol table entries.
  *
- * Errors:
- *              SYM       CANTDECODE    Can't decode.
- *
  * Return:      Success:        Non-negative, with *pp pointing to the first byte
  *                              after the last symbol.
  *
@@ -60,31 +52,29 @@ H5FL_BLK_EXTERN(str_buf);
  *              matzke@llnl.gov
  *              Jul 18 1997
  *
- * Modifications:
- *
  *-------------------------------------------------------------------------
  */
 herr_t
 H5G_ent_decode_vec(H5F_t *f, const uint8_t **pp, H5G_entry_t *ent, unsigned n)
 {
-    unsigned    u;
-    herr_t      ret_value=SUCCEED;       /* Return value */
+    unsigned    u;                      /* Local index variable */
+    herr_t      ret_value = SUCCEED;    /* Return value */
 
-    FUNC_ENTER_NOAPI(H5G_ent_decode_vec, FAIL);
+    FUNC_ENTER_NOAPI(H5G_ent_decode_vec, FAIL)
 
     /* check arguments */
-    assert(f);
-    assert(pp);
-    assert(ent);
+    HDassert(f);
+    HDassert(pp);
+    HDassert(ent);
 
     /* decode entries */
-    for (u = 0; u < n; u++)
-        if (H5G_ent_decode(f, pp, ent + u) < 0)
+    for(u = 0; u < n; u++)
+        if(H5G_ent_decode(f, pp, ent + u) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTDECODE, FAIL, "can't decode")
 
 done:
-    FUNC_LEAVE_NOAPI(ret_value);
-}
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5G_ent_decode_vec() */
 
 
 /*-------------------------------------------------------------------------
@@ -92,8 +82,6 @@ done:
  *
  * Purpose:     Decodes a symbol table entry pointed to by `*pp'.
  *
- * Errors:
- *
  * Return:      Success:        Non-negative with *pp pointing to the first byte
  *                              following the symbol table entry.
  *
@@ -103,25 +91,23 @@ done:
  *              matzke@llnl.gov
  *              Jul 18 1997
  *
- * Modifications:
- *	Robb Matzke, 17 Jul 1998
- * 	Added a 4-byte padding field for alignment and future expansion.
- *
  *-------------------------------------------------------------------------
  */
-static herr_t
+herr_t
 H5G_ent_decode(H5F_t *f, const uint8_t **pp, H5G_entry_t *ent)
 {
     const uint8_t	*p_ret = *pp;
     uint32_t		tmp;
+    herr_t      ret_value = SUCCEED;       /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5G_ent_decode)
+    FUNC_ENTER_NOAPI(H5G_ent_decode, FAIL)
 
     /* check arguments */
     HDassert(f);
     HDassert(pp);
     HDassert(ent);
 
+    /* Set the entry's file pointer */
     ent->file = f;
 
     /* decode header */
@@ -129,31 +115,31 @@ H5G_ent_decode(H5F_t *f, const uint8_t **pp, H5G_entry_t *ent)
     H5F_addr_decode(f, pp, &(ent->header));
     UINT32DECODE(*pp, tmp);
     *pp += 4; /*reserved*/
-    ent->type=(H5G_cache_type_t)tmp;
+    ent->type = (H5G_cache_type_t)tmp;
 
     /* decode scratch-pad */
-    switch (ent->type) {
+    switch(ent->type) {
         case H5G_NOTHING_CACHED:
             break;
 
         case H5G_CACHED_STAB:
-            assert(2 * H5F_SIZEOF_ADDR(f) <= H5G_SIZEOF_SCRATCH);
+            HDassert(2 * H5F_SIZEOF_ADDR(f) <= H5G_SIZEOF_SCRATCH);
             H5F_addr_decode(f, pp, &(ent->cache.stab.btree_addr));
             H5F_addr_decode(f, pp, &(ent->cache.stab.heap_addr));
             break;
 
         case H5G_CACHED_SLINK:
-            UINT32DECODE (*pp, ent->cache.slink.lval_offset);
+            UINT32DECODE(*pp, ent->cache.slink.lval_offset);
             break;
 
         default:
-            /* Error or unknown type. Bail out. */
-            return -1;
-    }
+            HGOTO_ERROR(H5E_SYM, H5E_BADVALUE, FAIL, "unknown symbol table entry cache type")
+    } /* end switch */
 
     *pp = p_ret + H5G_SIZEOF_ENTRY(f);
 
-    FUNC_LEAVE_NOAPI(SUCCEED)
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5G_ent_decode() */
 
 
@@ -163,9 +149,6 @@ H5G_ent_decode(H5F_t *f, const uint8_t **pp, H5G_entry_t *ent)
  * Purpose:     Same as H5G_ent_encode() except it does it for an array of
  *              symbol table entries.
  *
- * Errors:
- *              SYM       CANTENCODE    Can't encode.
- *
  * Return:      Success:        Non-negative, with *pp pointing to the first byte
  *                              after the last symbol.
  *
@@ -175,31 +158,29 @@ H5G_ent_decode(H5F_t *f, const uint8_t **pp, H5G_entry_t *ent)
  *              matzke@llnl.gov
  *              Jul 18 1997
  *
- * Modifications:
- *
  *-------------------------------------------------------------------------
  */
 herr_t
 H5G_ent_encode_vec(H5F_t *f, uint8_t **pp, const H5G_entry_t *ent, unsigned n)
 {
-    unsigned    u;
-    herr_t      ret_value=SUCCEED;       /* Return value */
+    unsigned    u;                      /* Local index variable */
+    herr_t      ret_value = SUCCEED;    /* Return value */
 
-    FUNC_ENTER_NOAPI(H5G_ent_encode_vec, FAIL);
+    FUNC_ENTER_NOAPI(H5G_ent_encode_vec, FAIL)
 
     /* check arguments */
-    assert(f);
-    assert(pp);
-    assert(ent);
+    HDassert(f);
+    HDassert(pp);
+    HDassert(ent);
 
     /* encode entries */
-    for (u = 0; u < n; u++)
-        if (H5G_ent_encode(f, pp, ent + u) < 0)
-            HGOTO_ERROR(H5E_SYM, H5E_CANTENCODE, FAIL, "can't encode");
+    for(u = 0; u < n; u++)
+        if(H5G_ent_encode(f, pp, ent + u) < 0)
+            HGOTO_ERROR(H5E_SYM, H5E_CANTENCODE, FAIL, "can't encode")
 
 done:
-    FUNC_LEAVE_NOAPI(ret_value);
-}
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5G_ent_encode_vec() */
 
 
 /*-------------------------------------------------------------------------
@@ -208,8 +189,6 @@ done:
  * Purpose:     Encodes the specified symbol table entry into the buffer
  *              pointed to by *pp.
  *
- * Errors:
- *
  * Return:      Success:        Non-negative, with *pp pointing to the first byte
  *                              after the symbol table entry.
  *
@@ -219,26 +198,22 @@ done:
  *              matzke@llnl.gov
  *              Jul 18 1997
  *
- * Modifications:
- *
- *      Robb Matzke, 8 Aug 1997
- *      Writes zeros for the bytes that aren't used so the file doesn't
- *      contain junk.
- *
  *-------------------------------------------------------------------------
  */
-static herr_t
-H5G_ent_encode(H5F_t *f, uint8_t **pp, const H5G_entry_t *ent)
+herr_t
+H5G_ent_encode(const H5F_t *f, uint8_t **pp, const H5G_entry_t *ent)
 {
-    uint8_t		*p_ret = *pp + H5G_SIZEOF_ENTRY(f);
+    uint8_t	*p_ret = *pp + H5G_SIZEOF_ENTRY(f);
+    herr_t      ret_value = SUCCEED;    /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5G_ent_encode);
+    FUNC_ENTER_NOAPI(H5G_ent_encode, FAIL)
 
     /* check arguments */
-    assert(f);
-    assert(pp);
+    HDassert(f);
+    HDassert(pp);
 
-    if (ent) {
+    /* Check for actual entry to encode */
+    if(ent) {
         /* encode header */
         H5F_ENCODE_LENGTH(f, *pp, ent->name_off);
         H5F_addr_encode(f, pp, ent->header);
@@ -246,37 +221,39 @@ H5G_ent_encode(H5F_t *f, uint8_t **pp, const H5G_entry_t *ent)
 	UINT32ENCODE(*pp, 0); /*reserved*/
 
         /* encode scratch-pad */
-        switch (ent->type) {
+        switch(ent->type) {
             case H5G_NOTHING_CACHED:
                 break;
 
             case H5G_CACHED_STAB:
-                assert(2 * H5F_SIZEOF_ADDR(f) <= H5G_SIZEOF_SCRATCH);
+                HDassert(2 * H5F_SIZEOF_ADDR(f) <= H5G_SIZEOF_SCRATCH);
                 H5F_addr_encode(f, pp, ent->cache.stab.btree_addr);
                 H5F_addr_encode(f, pp, ent->cache.stab.heap_addr);
                 break;
 
             case H5G_CACHED_SLINK:
-                UINT32ENCODE (*pp, ent->cache.slink.lval_offset);
+                UINT32ENCODE(*pp, ent->cache.slink.lval_offset);
                 break;
 
             default:
-                /* Unknown cached type. Bail out. */
-                return -1;
-        }
-    } else {
+                HGOTO_ERROR(H5E_SYM, H5E_BADVALUE, FAIL, "unknown symbol table entry cache type")
+        } /* end switch */
+    } /* end if */
+    else {
         H5F_ENCODE_LENGTH(f, *pp, 0);
         H5F_addr_encode(f, pp, HADDR_UNDEF);
         UINT32ENCODE(*pp, H5G_NOTHING_CACHED);
 	UINT32ENCODE(*pp, 0); /*reserved*/
-    }
+    } /* end else */
 
     /* fill with zero */
-    while (*pp < p_ret) *(*pp)++ = 0;
+    while(*pp < p_ret)
+        *(*pp)++ = 0;
     *pp = p_ret;
 
-    FUNC_LEAVE_NOAPI(SUCCEED);
-}
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5G_ent_encode() */
 
 
 /*-------------------------------------------------------------------------
diff --git a/src/H5Gprivate.h b/src/H5Gprivate.h
index 7f001e0..ff20fe6 100644
--- a/src/H5Gprivate.h
+++ b/src/H5Gprivate.h
@@ -129,10 +129,8 @@ typedef struct {
 } H5G_name_t;
 
 /* Forward declarations (for prototypes & struct definitions) */
-struct H5P_genplist_t;
 struct H5O_loc_t;
 struct H5O_link_t;
-struct H5O_t;
 
 /*
  * The "location" of an object in a group hierarchy.  This points to an object
@@ -181,8 +179,9 @@ H5_DLL herr_t H5G_node_debug(H5F_t *f, hid_t dxpl_id, haddr_t addr, FILE *stream
 /*
  * These functions operate on group object locations.
  */
-H5_DLL herr_t H5G_root_ent_decode(H5F_t *f, const uint8_t **pp);
-H5_DLL herr_t H5G_root_ent_encode(H5F_t *f, uint8_t **pp);
+H5_DLL herr_t H5G_ent_encode(const H5F_t *f, uint8_t **pp,
+    const H5G_entry_t *ent);
+H5_DLL herr_t H5G_ent_decode(H5F_t *f, const uint8_t **pp, H5G_entry_t *ent/*out*/);
 
 /*
  * These functions operate on group hierarchy names.
diff --git a/src/H5Groot.c b/src/H5Groot.c
index 9d3fc6f..5d07142 100644
--- a/src/H5Groot.c
+++ b/src/H5Groot.c
@@ -76,99 +76,6 @@ H5G_rootof(H5F_t *f)
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5G_root_ent_decode
- *
- * Purpose:     Decodes the root group symbol table entry into the file
- *              structure, and updates the root group address in the file
- *              structure.
- *
- * Return:      Success:        Non-negative with *pp pointing to the first byte
- *                              following the symbol table entry.
- *
- *              Failure:        Negative
- *
- * Programmer:  Quincey Koziol
- *              koziol@ncsa.uiuc.edu
- *              Sep 26 2005
- *
- *-------------------------------------------------------------------------
- */
-herr_t
-H5G_root_ent_decode(H5F_t *f, const uint8_t **pp)
-{
-    const uint8_t	*p_ret = *pp + H5G_SIZEOF_ENTRY(f);
-    herr_t          ret_value = SUCCEED;         /* Return value */
-
-    FUNC_ENTER_NOAPI(H5G_root_ent_decode, FAIL)
-
-    /* check arguments */
-    HDassert(f);
-    HDassert(pp);
-
-    /* Allocate space for the root group symbol table entry */
-    HDassert(!f->shared->root_ent);
-    if(NULL == (f->shared->root_ent = (H5G_entry_t *)H5MM_calloc(sizeof(H5G_entry_t))))
-        HGOTO_ERROR(H5E_RESOURCE, H5E_CANTALLOC, FAIL, "can't allocate space for symbol table entry")
-
-    /* decode the root group symbol table entry */
-    if(H5G_ent_decode_vec(f, pp, f->shared->root_ent, 1) < 0)
-        HGOTO_ERROR(H5E_SYM, H5E_CANTDECODE, FAIL, "can't decode symbol table entry")
-
-    /* Set the root group address to the correct value */
-    f->shared->root_addr = f->shared->root_ent->header;
-
-    /* Set decode pointer */
-    *pp = p_ret;
-
-done:
-    FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5G_root_ent_decode() */
-
-
-/*-------------------------------------------------------------------------
- * Function:    H5G_root_ent_encode
- *
- * Purpose:     Encodes the root group symbol table entry into the buffer
- *              pointed to by *pp.
- *
- * Return:      Success:        Non-negative, with *pp pointing to the first byte
- *                              after the symbol table entry.
- *
- *              Failure:        Negative
- *
- * Programmer:  Quincey Koziol
- *              koziol@ncsa.uiuc.edu
- *              Sep 26 2005
- *
- *-------------------------------------------------------------------------
- */
-herr_t
-H5G_root_ent_encode(H5F_t *f, uint8_t **pp)
-{
-    uint8_t		*p_ret = *pp + H5G_SIZEOF_ENTRY(f);
-    herr_t              ret_value = SUCCEED;         /* Return value */
-
-    FUNC_ENTER_NOAPI(H5G_root_ent_encode, FAIL)
-
-    /* check arguments */
-    HDassert(f);
-    HDassert(f->shared);
-    HDassert(f->shared->root_ent);
-    HDassert(pp);
-
-    /* Encode entry */
-    if(H5G_ent_encode_vec(f, pp, f->shared->root_ent, 1) < 0)
-        HGOTO_ERROR(H5E_SYM, H5E_CANTENCODE, FAIL, "can't encode symbol table entry")
-
-    /* Set encode pointer */
-    *pp = p_ret;
-
-done:
-    FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5G_root_ent_encode() */
-
-
-/*-------------------------------------------------------------------------
  * Function:	H5G_mkroot
  *
  * Purpose:	Creates a root group in an empty file and opens it.  If a
@@ -191,12 +98,15 @@ H5G_mkroot(H5F_t *f, hid_t dxpl_id, hbool_t create_root)
 {
     H5G_loc_t   root_loc;               /* Root location information */
     htri_t      stab_exists = -1;       /* Whether the symbol table exists */
-    herr_t ret_value = SUCCEED;         /* Return value */
+    hbool_t     sblock_dirty = FALSE;   /* Whether superblock was dirtied */
+    herr_t      ret_value = SUCCEED;    /* Return value */
 
     FUNC_ENTER_NOAPI(H5G_mkroot, FAIL)
 
     /* check args */
     HDassert(f);
+    HDassert(f->shared);
+    HDassert(f->shared->sblock);
 
     /* Check if the root group is already initialized */
     if(f->shared->root_grp)
@@ -230,7 +140,6 @@ H5G_mkroot(H5F_t *f, hid_t dxpl_id, hbool_t create_root)
         H5P_genplist_t *fc_plist;       /* File creation property list */
         H5O_ginfo_t     ginfo;          /* Group info parameters */
         H5O_linfo_t     linfo;          /* Link info parameters */
-        unsigned        super_vers;     /* Superblock version */
 
         /* Get the file creation property list */
         /* (Which is a sub-class of the group creation property class) */
@@ -245,34 +154,33 @@ H5G_mkroot(H5F_t *f, hid_t dxpl_id, hbool_t create_root)
         if(H5P_get(fc_plist, H5G_CRT_LINK_INFO_NAME, &linfo) < 0)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get link info")
 
-        /* Get the superblock version */
-        if(H5P_get(fc_plist, H5F_CRT_SUPER_VERS_NAME, &super_vers) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get superblock version")
-
         /* Create root group */
 	if(H5G_obj_create(f, dxpl_id, &ginfo, &linfo, f->shared->fcpl_id, root_loc.oloc/*out*/) < 0)
 	    HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create group entry")
 	if(1 != H5O_link(root_loc.oloc, 1, dxpl_id))
 	    HGOTO_ERROR(H5E_SYM, H5E_LINKCOUNT, FAIL, "internal error (wrong link count)")
 
+        /* Mark superblock dirty, so root group info is flushed */
+        sblock_dirty = TRUE;
+
         /* Create the root group symbol table entry */
-        HDassert(!f->shared->root_ent);
-        if(super_vers < HDF5_SUPERBLOCK_VERSION_2) {
+        HDassert(!f->shared->sblock->root_ent);
+        if(f->shared->sblock->super_vers < HDF5_SUPERBLOCK_VERSION_2) {
             /* Allocate space for the root group symbol table entry */
-            if(NULL == (f->shared->root_ent = (H5G_entry_t *) H5MM_calloc(sizeof(H5G_entry_t))))
+            if(NULL == (f->shared->sblock->root_ent = (H5G_entry_t *)H5MM_calloc(sizeof(H5G_entry_t))))
                 HGOTO_ERROR(H5E_RESOURCE, H5E_CANTALLOC, FAIL, "can't allocate space for symbol table entry")
 
             /* Initialize the root group symbol table entry */
-            f->shared->root_ent->dirty = TRUE;
-            f->shared->root_ent->type = H5G_NOTHING_CACHED; /* We will cache the stab later */
-            f->shared->root_ent->name_off = 0;  /* No name (yet) */
-            f->shared->root_ent->header = root_loc.oloc->addr;
-            f->shared->root_ent->file = root_loc.oloc->file;
+            f->shared->sblock->root_ent->dirty = TRUE;
+            f->shared->sblock->root_ent->type = H5G_NOTHING_CACHED; /* We will cache the stab later */
+            f->shared->sblock->root_ent->name_off = 0;  /* No name (yet) */
+            f->shared->sblock->root_ent->header = root_loc.oloc->addr;
+            f->shared->sblock->root_ent->file = root_loc.oloc->file;
         } /* end if */
     } /* end if */
     else {
         /* Create root group object location from f */
-        root_loc.oloc->addr = f->shared->root_addr;
+        root_loc.oloc->addr = f->shared->sblock->root_addr;
         root_loc.oloc->file = f;
 
 	/*
@@ -282,7 +190,7 @@ H5G_mkroot(H5F_t *f, hid_t dxpl_id, hbool_t create_root)
 	    HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open root group")
 
         /* Actions to take if the symbol table information is cached */
-        if(f->shared->root_ent && f->shared->root_ent->type == H5G_CACHED_STAB) {
+        if(f->shared->sblock->root_ent && f->shared->sblock->root_ent->type == H5G_CACHED_STAB) {
             /* Check for the situation where the symbol table is cached but does
              * not exist.  This can happen if, for example, an external link is
              * added to the root group. */
@@ -291,7 +199,7 @@ H5G_mkroot(H5F_t *f, hid_t dxpl_id, hbool_t create_root)
 
             /* Remove the cache if the stab does not exist */
             if(!stab_exists)
-                f->shared->root_ent->type = H5G_NOTHING_CACHED;
+                f->shared->sblock->root_ent->type = H5G_NOTHING_CACHED;
 #ifndef H5_STRICT_FORMAT_CHECKS
             /* If symbol table information is cached, check if we should replace the
             * symbol table message with the cached symbol table information */
@@ -299,8 +207,8 @@ H5G_mkroot(H5F_t *f, hid_t dxpl_id, hbool_t create_root)
                 H5O_stab_t      cached_stab;
 
                 /* Retrieve the cached symbol table information */
-                cached_stab.btree_addr = f->shared->root_ent->cache.stab.btree_addr;
-                cached_stab.heap_addr = f->shared->root_ent->cache.stab.heap_addr;
+                cached_stab.btree_addr = f->shared->sblock->root_ent->cache.stab.btree_addr;
+                cached_stab.heap_addr = f->shared->sblock->root_ent->cache.stab.heap_addr;
 
                 /* Check if the symbol table message is valid, and replace with the
                 * cached symbol table if necessary */
@@ -316,8 +224,8 @@ H5G_mkroot(H5F_t *f, hid_t dxpl_id, hbool_t create_root)
      * present, so we don't need to check the superblock version.  We do this if
      * we have write access, the root entry has been allocated (i.e.
      * super_vers < 2) and the stab info is not already cached. */
-    if((H5F_INTENT(f) & H5F_ACC_RDWR) && stab_exists != FALSE && f->shared->root_ent
-            && f->shared->root_ent->type != H5G_CACHED_STAB) {
+    if((H5F_INTENT(f) & H5F_ACC_RDWR) && stab_exists != FALSE && f->shared->sblock->root_ent
+            && f->shared->sblock->root_ent->type != H5G_CACHED_STAB) {
         H5O_stab_t      stab;           /* Symbol table */
 
         /* Check if the stab message exists.  It's possible for the root group
@@ -332,9 +240,12 @@ H5G_mkroot(H5F_t *f, hid_t dxpl_id, hbool_t create_root)
                 HGOTO_ERROR(H5E_SYM, H5E_BADMESG, FAIL, "unable to read symbol table message")
 
             /* Update the root group symbol table entry */
-            f->shared->root_ent->type = H5G_CACHED_STAB;
-            f->shared->root_ent->cache.stab.btree_addr = stab.btree_addr;
-            f->shared->root_ent->cache.stab.heap_addr = stab.heap_addr;
+            f->shared->sblock->root_ent->type = H5G_CACHED_STAB;
+            f->shared->sblock->root_ent->cache.stab.btree_addr = stab.btree_addr;
+            f->shared->sblock->root_ent->cache.stab.heap_addr = stab.heap_addr;
+
+            /* Mark superblock dirty, so root group info is flushed */
+            sblock_dirty = TRUE;
         } /* end if */
     } /* end if */
 
@@ -347,7 +258,7 @@ H5G_mkroot(H5F_t *f, hid_t dxpl_id, hbool_t create_root)
      * in the number of open objects in the file.
      */
     HDassert((1 == f->nopen_objs) ||
-            (2 == f->nopen_objs && HADDR_UNDEF != f->shared->extension_addr));
+            (2 == f->nopen_objs && HADDR_UNDEF != f->shared->sblock->ext_addr));
     f->nopen_objs--;
 
 done:
@@ -359,10 +270,16 @@ done:
                 f->shared->root_grp->shared = H5FL_FREE(H5G_shared_t, f->shared->root_grp->shared);
             f->shared->root_grp = H5FL_FREE(H5G_t, f->shared->root_grp);
         } /* end if */
-        f->shared->root_ent = (H5G_entry_t *) H5MM_xfree(f->shared->root_ent);
+        if(f->shared->sblock)
+            f->shared->sblock->root_ent = (H5G_entry_t *)H5MM_xfree(f->shared->sblock->root_ent);
         H5G_name_free(root_loc.path);
     } /* end if */
 
+    /* Mark superblock dirty in cache, if necessary */
+    if(sblock_dirty)
+        if(H5AC_mark_pinned_or_protected_entry_dirty(f, f->shared->sblock) < 0)
+            HDONE_ERROR(H5E_FILE, H5E_CANTMARKDIRTY, FAIL, "unable to mark superblock as dirty")
+
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5G_mkroot() */
 
diff --git a/src/H5MF.c b/src/H5MF.c
index dfd1547..639a65f 100644
--- a/src/H5MF.c
+++ b/src/H5MF.c
@@ -719,11 +719,15 @@ H5MF_try_extend(H5F_t *f, hid_t dxpl_id, H5FD_mem_t alloc_type, haddr_t addr,
 HDfprintf(stderr, "%s: Entering: alloc_type = %u, addr = %a, size = %Hu, extra_requested = %Hu\n", FUNC, (unsigned)alloc_type, addr, size, extra_requested);
 #endif /* H5MF_ALLOC_DEBUG */
 
+    /* Sanity check */
+    HDassert(f);
+    HDassert(H5F_INTENT(f) & H5F_ACC_RDWR);
+
     /* Compute end of block to extend */
     end = addr + size;
 
     /* Check if the block is exactly at the end of the file */
-    if((ret_value = H5FD_try_extend(f->shared->lf, alloc_type, end, extra_requested)) < 0)
+    if((ret_value = H5FD_try_extend(f->shared->lf, alloc_type, f, end, extra_requested)) < 0)
         HGOTO_ERROR(H5E_RESOURCE, H5E_CANTEXTEND, FAIL, "error extending file")
     else if(ret_value == FALSE) {
         H5F_blk_aggr_t *aggr;   /* Aggregator to use */
@@ -757,6 +761,7 @@ HDfprintf(stderr, "%s: Leaving: ret_value = %t\n", FUNC, ret_value);
 #ifdef H5MF_ALLOC_DEBUG_DUMP
 H5MF_sects_dump(f, dxpl_id, stderr);
 #endif /* H5MF_ALLOC_DEBUG_DUMP */
+
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5MF_try_extend() */
 
diff --git a/src/H5MFaggr.c b/src/H5MFaggr.c
index 616d705..0b1bc91 100644
--- a/src/H5MFaggr.c
+++ b/src/H5MFaggr.c
@@ -155,8 +155,7 @@ H5MF_aggr_alloc(H5F_t *f, hid_t dxpl_id, H5F_blk_aggr_t *aggr,
     hsize_t 	alignment = 0, mis_align = 0;
     haddr_t	frag_addr = 0, eoa_frag_addr = 0;
     hsize_t	frag_size = 0, eoa_frag_size = 0;
-    haddr_t	eoa = 0, new_space = 0;
-    htri_t  	extended = 0;
+    haddr_t	eoa = 0;                /* Initial EOA for the file */
     H5FD_mem_t 	alloc_type, other_alloc_type;
     haddr_t 	ret_value;              /* Return value */
 
@@ -202,6 +201,7 @@ HDfprintf(stderr, "%s: aggr = {%a, %Hu, %Hu}\n", FUNC, aggr->addr, aggr->tot_siz
 
         /* Check if the space requested is larger than the space left in the block */
         if((size + frag_size) > aggr->size) {
+            htri_t  	extended = FALSE;   /* Whether the file was extended */
 
             /* Check if the block asked for is too large for 'normal' aggregator block */
             if(size >= aggr->alloc_size) {
@@ -211,7 +211,7 @@ HDfprintf(stderr, "%s: aggr = {%a, %Hu, %Hu}\n", FUNC, aggr->addr, aggr->tot_siz
                 if(H5F_addr_gt((aggr->addr + aggr->size + ext_size), f->shared->tmp_addr))
                     HGOTO_ERROR(H5E_RESOURCE, H5E_BADRANGE, HADDR_UNDEF, "'normal' file space allocation request will overlap into 'temporary' file space")
 
-		if ((aggr->addr > 0) && (extended = H5FD_try_extend(f->shared->lf, alloc_type, aggr->addr + aggr->size, ext_size)) < 0)
+		if ((aggr->addr > 0) && (extended = H5FD_try_extend(f->shared->lf, alloc_type, f, aggr->addr + aggr->size, ext_size)) < 0)
 		    HGOTO_ERROR(H5E_RESOURCE, H5E_CANTALLOC, HADDR_UNDEF, "can't extending space")
 		else if (extended) {
 		    /* aggr->size is unchanged */
@@ -226,7 +226,7 @@ HDfprintf(stderr, "%s: aggr = {%a, %Hu, %Hu}\n", FUNC, aggr->addr, aggr->tot_siz
 		    if ((other_aggr->size > 0) && (H5F_addr_eq((other_aggr->addr + other_aggr->size), eoa)) &&
 			((other_aggr->tot_size - other_aggr->size) >= other_aggr->alloc_size)) {
 
-                            if(H5FD_free(f->shared->lf, dxpl_id, other_alloc_type, other_aggr->addr, other_aggr->size) < 0)
+                            if(H5FD_free(f->shared->lf, dxpl_id, other_alloc_type, f, other_aggr->addr, other_aggr->size) < 0)
                                 HGOTO_ERROR(H5E_VFL, H5E_CANTFREE, HADDR_UNDEF, "can't free aggregation block")
 
                             other_aggr->addr = 0;
@@ -235,11 +235,8 @@ HDfprintf(stderr, "%s: aggr = {%a, %Hu, %Hu}\n", FUNC, aggr->addr, aggr->tot_siz
 		    } /* end if */
 
                     /* Allocate space from the VFD (i.e. at the end of the file) */
-		    if(HADDR_UNDEF == (new_space = H5FD_alloc(f->shared->lf, dxpl_id, type, size, &eoa_frag_addr, &eoa_frag_size)))
+		    if(HADDR_UNDEF == (ret_value = H5FD_alloc(f->shared->lf, dxpl_id, type, f, size, &eoa_frag_addr, &eoa_frag_size)))
 			HGOTO_ERROR(H5E_VFL, H5E_CANTALLOC, HADDR_UNDEF, "can't allocate aggregation block")
-
-                    /* Use the new space allocated, leaving the old block */
-                    ret_value = new_space;
                 } /* end else */
             } /* end if */
 	    else {
@@ -257,13 +254,15 @@ HDfprintf(stderr, "%s: Allocating block\n", FUNC);
                 if(H5F_addr_gt((aggr->addr + aggr->size + ext_size), f->shared->tmp_addr))
                     HGOTO_ERROR(H5E_RESOURCE, H5E_BADRANGE, HADDR_UNDEF, "'normal' file space allocation request will overlap into 'temporary' file space")
 
-		if((aggr->addr > 0) && (extended = H5FD_try_extend(f->shared->lf, alloc_type, aggr->addr + aggr->size, ext_size)) < 0)
+		if((aggr->addr > 0) && (extended = H5FD_try_extend(f->shared->lf, alloc_type, f, aggr->addr + aggr->size, ext_size)) < 0)
 		    HGOTO_ERROR(H5E_RESOURCE, H5E_CANTALLOC, HADDR_UNDEF, "can't extending space")
 		else if (extended) {
 		    aggr->addr += frag_size;
 		    aggr->size += (ext_size - frag_size);
 		    aggr->tot_size += ext_size;
 		} else {
+                    haddr_t new_space;          /* Address of new space allocated */
+
                     /* Check for overlapping into file's temporary allocation space */
                     if(H5F_addr_gt((eoa + aggr->alloc_size), f->shared->tmp_addr))
                         HGOTO_ERROR(H5E_RESOURCE, H5E_BADRANGE, HADDR_UNDEF, "'normal' file space allocation request will overlap into 'temporary' file space")
@@ -271,7 +270,7 @@ HDfprintf(stderr, "%s: Allocating block\n", FUNC);
 		    if((other_aggr->size > 0) && (H5F_addr_eq((other_aggr->addr + other_aggr->size), eoa)) &&
 			((other_aggr->tot_size - other_aggr->size) >= other_aggr->alloc_size)) {
 
-                            if(H5FD_free(f->shared->lf, dxpl_id, other_alloc_type, other_aggr->addr, other_aggr->size) < 0)
+                            if(H5FD_free(f->shared->lf, dxpl_id, other_alloc_type, f, other_aggr->addr, other_aggr->size) < 0)
                                 HGOTO_ERROR(H5E_VFL, H5E_CANTFREE, HADDR_UNDEF, "can't free aggregation block")
                             other_aggr->addr = 0;
                             other_aggr->tot_size = 0;
@@ -279,7 +278,7 @@ HDfprintf(stderr, "%s: Allocating block\n", FUNC);
 		    } /* end if */
 
                     /* Allocate space from the VFD (i.e. at the end of the file) */
-		    if(HADDR_UNDEF == (new_space = H5FD_alloc(f->shared->lf, dxpl_id, alloc_type, aggr->alloc_size, &eoa_frag_addr, &eoa_frag_size)))
+		    if(HADDR_UNDEF == (new_space = H5FD_alloc(f->shared->lf, dxpl_id, alloc_type, f, aggr->alloc_size, &eoa_frag_addr, &eoa_frag_size)))
 			HGOTO_ERROR(H5E_VFL, H5E_CANTALLOC, HADDR_UNDEF, "can't allocate aggregation block")
 
                     /* Return the unused portion of the block to a free list */
@@ -327,8 +326,9 @@ HDfprintf(stderr, "%s: Allocating block\n", FUNC);
             HGOTO_ERROR(H5E_RESOURCE, H5E_BADRANGE, HADDR_UNDEF, "'normal' file space allocation request will overlap into 'temporary' file space")
 
         /* Allocate data from the file */
-        if(HADDR_UNDEF == (ret_value = H5FD_alloc(f->shared->lf, dxpl_id, type, size, &eoa_frag_addr, &eoa_frag_size)))
+        if(HADDR_UNDEF == (ret_value = H5FD_alloc(f->shared->lf, dxpl_id, type, f, size, &eoa_frag_addr, &eoa_frag_size)))
             HGOTO_ERROR(H5E_RESOURCE, H5E_CANTALLOC, HADDR_UNDEF, "can't allocate file space")
+
         /* Check if fragment was generated */
 	if(eoa_frag_size)
             /* Put fragment on the free list */
@@ -343,6 +343,7 @@ done:
 #ifdef H5MF_AGGR_DEBUG
 HDfprintf(stderr, "%s: ret_value = %a\n", FUNC, ret_value);
 #endif /* H5MF_AGGR_DEBUG */
+
     if(alignment)
 	HDassert(!(ret_value % alignment));
     FUNC_LEAVE_NOAPI(ret_value)
@@ -386,7 +387,7 @@ H5MF_aggr_try_extend(const H5F_t *f, H5F_blk_aggr_t *aggr, H5FD_mem_t type,
             /* If the aggregator block is at the end of the file, extend the
              * file and "bubble" the aggregator up
              */
-            if((ret_value = H5FD_try_extend(f->shared->lf, type, (aggr->addr + aggr->size), extra_requested)) < 0)
+            if((ret_value = H5FD_try_extend(f->shared->lf, type, f, (aggr->addr + aggr->size), extra_requested)) < 0)
                 HGOTO_ERROR(H5E_RESOURCE, H5E_CANTEXTEND, FAIL, "error extending file")
             else if(ret_value == TRUE) {
                 /* Shift the aggregator block by the extra requested */
@@ -638,8 +639,8 @@ HDfprintf(stderr, "%s: tmp_addr = %a, tmp_size = %Hu\n", FUNC, tmp_addr, tmp_siz
         aggr->size = 0;
 
         /* Return the unused portion of the metadata block to the file */
-        if(tmp_size > 0)
-            if(H5FD_free(f->shared->lf, dxpl_id, alloc_type, tmp_addr, tmp_size) < 0)
+        if(tmp_size > 0 && (H5F_INTENT(f) & H5F_ACC_RDWR))
+            if(H5FD_free(f->shared->lf, dxpl_id, alloc_type, f, tmp_addr, tmp_size) < 0)
                 HGOTO_ERROR(H5E_RESOURCE, H5E_CANTFREE, FAIL, "can't free space")
     } /* end if */
 
diff --git a/src/H5MFsection.c b/src/H5MFsection.c
index 0dc43c3..d10b6b1 100644
--- a/src/H5MFsection.c
+++ b/src/H5MFsection.c
@@ -404,8 +404,11 @@ H5MF_sect_simple_shrink(H5FS_section_info_t **_sect, void *_udata)
 
     /* Check for shrinking file */
     if(H5MF_SHRINK_EOA == udata->shrink) {
+        /* Sanity check */
+        HDassert(H5F_INTENT(udata->f) & H5F_ACC_RDWR);
+
         /* Release section's space at EOA with file driver */
-        if(H5FD_free(udata->f->shared->lf, udata->dxpl_id, udata->alloc_type, (*sect)->sect_info.addr, (*sect)->sect_info.size) < 0)
+        if(H5FD_free(udata->f->shared->lf, udata->dxpl_id, udata->alloc_type, udata->f, (*sect)->sect_info.addr, (*sect)->sect_info.size) < 0)
             HGOTO_ERROR(H5E_RESOURCE, H5E_CANTFREE, FAIL, "driver free request failed")
     } /* end if */
     else {
diff --git a/src/Makefile.am b/src/Makefile.am
index eb264f2..fb73bbf 100755
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -54,7 +54,7 @@ libhdf5_la_SOURCES= H5.c H5checksum.c H5dbg.c H5system.c H5timer.c H5trace.c \
         H5EA.c H5EAcache.c H5EAdbg.c H5EAdblkpage.c H5EAdblock.c H5EAhdr.c \
         H5EAiblock.c H5EAint.c H5EAsblock.c H5EAstat.c H5EAtest.c \
         H5F.c H5Faccum.c H5Fdbg.c H5Ffake.c H5Fio.c H5Fmount.c H5Fmpi.c H5Fquery.c \
-        H5Fsfile.c H5Fsuper.c H5Ftest.c \
+        H5Fsfile.c H5Fsuper.c H5Fsuper_cache.c H5Ftest.c \
         H5FA.c H5FAcache.c H5FAdbg.c H5FAdblock.c H5FAdblkpage.c H5FAhdr.c \
         H5FAstat.c H5FAtest.c \
         H5FD.c H5FDcore.c  \
diff --git a/src/Makefile.in b/src/Makefile.in
index 3126c7b..cc096cf 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -107,34 +107,35 @@ am_libhdf5_la_OBJECTS = H5.lo H5checksum.lo H5dbg.lo H5system.lo \
 	H5EAdblkpage.lo H5EAdblock.lo H5EAhdr.lo H5EAiblock.lo \
 	H5EAint.lo H5EAsblock.lo H5EAstat.lo H5EAtest.lo H5F.lo \
 	H5Faccum.lo H5Fdbg.lo H5Ffake.lo H5Fio.lo H5Fmount.lo \
-	H5Fmpi.lo H5Fquery.lo H5Fsfile.lo H5Fsuper.lo H5Ftest.lo \
-	H5FA.lo H5FAcache.lo H5FAdbg.lo H5FAdblock.lo H5FAdblkpage.lo \
-	H5FAhdr.lo H5FAstat.lo H5FAtest.lo H5FD.lo H5FDcore.lo \
-	H5FDdirect.lo H5FDfamily.lo H5FDint.lo H5FDlog.lo H5FDmpi.lo \
-	H5FDmpio.lo H5FDmpiposix.lo H5FDmulti.lo H5FDsec2.lo \
-	H5FDspace.lo H5FDstdio.lo H5FL.lo H5FO.lo H5FS.lo H5FScache.lo \
-	H5FSdbg.lo H5FSsection.lo H5FSstat.lo H5FStest.lo H5G.lo \
-	H5Gbtree2.lo H5Gcache.lo H5Gcompact.lo H5Gdense.lo \
-	H5Gdeprec.lo H5Gent.lo H5Gint.lo H5Glink.lo H5Gloc.lo \
-	H5Gname.lo H5Gnode.lo H5Gobj.lo H5Goh.lo H5Groot.lo H5Gstab.lo \
-	H5Gtest.lo H5Gtraverse.lo H5HF.lo H5HFbtree2.lo H5HFcache.lo \
-	H5HFdbg.lo H5HFdblock.lo H5HFdtable.lo H5HFhdr.lo H5HFhuge.lo \
-	H5HFiblock.lo H5HFiter.lo H5HFman.lo H5HFsection.lo \
-	H5HFspace.lo H5HFstat.lo H5HFtest.lo H5HFtiny.lo H5HG.lo \
-	H5HGcache.lo H5HGdbg.lo H5HL.lo H5HLcache.lo H5HLdbg.lo \
-	H5HP.lo H5I.lo H5L.lo H5Lexternal.lo H5MF.lo H5MFaggr.lo \
-	H5MFdbg.lo H5MFsection.lo H5MM.lo H5MP.lo H5MPtest.lo H5O.lo \
-	H5Oainfo.lo H5Oalloc.lo H5Oattr.lo H5Oattribute.lo H5Obogus.lo \
-	H5Obtreek.lo H5Ocache.lo H5Ocont.lo H5Ocopy.lo H5Odbg.lo \
-	H5Odrvinfo.lo H5Odtype.lo H5Oefl.lo H5Ofill.lo H5Oginfo.lo \
-	H5Olayout.lo H5Olinfo.lo H5Olink.lo H5Omessage.lo H5Omtime.lo \
-	H5Oname.lo H5Onull.lo H5Opline.lo H5Orefcount.lo H5Osdspace.lo \
-	H5Oshared.lo H5Ostab.lo H5Oshmesg.lo H5Otest.lo H5Ounknown.lo \
-	H5P.lo H5Pacpl.lo H5Pdapl.lo H5Pdcpl.lo H5Pdeprec.lo \
-	H5Pdxpl.lo H5Pfapl.lo H5Pfcpl.lo H5Pfmpl.lo H5Pgcpl.lo \
-	H5Pint.lo H5Plapl.lo H5Plcpl.lo H5Pocpl.lo H5Pocpypl.lo \
-	H5Pstrcpl.lo H5Ptest.lo H5R.lo H5Rdeprec.lo H5RC.lo H5RS.lo \
-	H5S.lo H5Sall.lo H5Sdbg.lo H5Shyper.lo H5Smpio.lo H5Snone.lo \
+	H5Fmpi.lo H5Fquery.lo H5Fsfile.lo H5Fsuper.lo \
+	H5Fsuper_cache.lo H5Ftest.lo H5FA.lo H5FAcache.lo H5FAdbg.lo \
+	H5FAdblock.lo H5FAdblkpage.lo H5FAhdr.lo H5FAstat.lo \
+	H5FAtest.lo H5FD.lo H5FDcore.lo H5FDdirect.lo H5FDfamily.lo \
+	H5FDint.lo H5FDlog.lo H5FDmpi.lo H5FDmpio.lo H5FDmpiposix.lo \
+	H5FDmulti.lo H5FDsec2.lo H5FDspace.lo H5FDstdio.lo H5FL.lo \
+	H5FO.lo H5FS.lo H5FScache.lo H5FSdbg.lo H5FSsection.lo \
+	H5FSstat.lo H5FStest.lo H5G.lo H5Gbtree2.lo H5Gcache.lo \
+	H5Gcompact.lo H5Gdense.lo H5Gdeprec.lo H5Gent.lo H5Gint.lo \
+	H5Glink.lo H5Gloc.lo H5Gname.lo H5Gnode.lo H5Gobj.lo H5Goh.lo \
+	H5Groot.lo H5Gstab.lo H5Gtest.lo H5Gtraverse.lo H5HF.lo \
+	H5HFbtree2.lo H5HFcache.lo H5HFdbg.lo H5HFdblock.lo \
+	H5HFdtable.lo H5HFhdr.lo H5HFhuge.lo H5HFiblock.lo H5HFiter.lo \
+	H5HFman.lo H5HFsection.lo H5HFspace.lo H5HFstat.lo H5HFtest.lo \
+	H5HFtiny.lo H5HG.lo H5HGcache.lo H5HGdbg.lo H5HL.lo \
+	H5HLcache.lo H5HLdbg.lo H5HP.lo H5I.lo H5L.lo H5Lexternal.lo \
+	H5MF.lo H5MFaggr.lo H5MFdbg.lo H5MFsection.lo H5MM.lo H5MP.lo \
+	H5MPtest.lo H5O.lo H5Oainfo.lo H5Oalloc.lo H5Oattr.lo \
+	H5Oattribute.lo H5Obogus.lo H5Obtreek.lo H5Ocache.lo \
+	H5Ocont.lo H5Ocopy.lo H5Odbg.lo H5Odrvinfo.lo H5Odtype.lo \
+	H5Oefl.lo H5Ofill.lo H5Oginfo.lo H5Olayout.lo H5Olinfo.lo \
+	H5Olink.lo H5Omessage.lo H5Omtime.lo H5Oname.lo H5Onull.lo \
+	H5Opline.lo H5Orefcount.lo H5Osdspace.lo H5Oshared.lo \
+	H5Ostab.lo H5Oshmesg.lo H5Otest.lo H5Ounknown.lo H5P.lo \
+	H5Pacpl.lo H5Pdapl.lo H5Pdcpl.lo H5Pdeprec.lo H5Pdxpl.lo \
+	H5Pfapl.lo H5Pfcpl.lo H5Pfmpl.lo H5Pgcpl.lo H5Pint.lo \
+	H5Plapl.lo H5Plcpl.lo H5Pocpl.lo H5Pocpypl.lo H5Pstrcpl.lo \
+	H5Ptest.lo H5R.lo H5Rdeprec.lo H5RC.lo H5RS.lo H5S.lo \
+	H5Sall.lo H5Sdbg.lo H5Shyper.lo H5Smpio.lo H5Snone.lo \
 	H5Spoint.lo H5Sselect.lo H5Stest.lo H5SL.lo H5SM.lo \
 	H5SMbtree2.lo H5SMcache.lo H5SMtest.lo H5ST.lo H5T.lo \
 	H5Tarray.lo H5Tbit.lo H5Tcommit.lo H5Tcompound.lo H5Tconv.lo \
@@ -460,7 +461,7 @@ libhdf5_la_SOURCES = H5.c H5checksum.c H5dbg.c H5system.c H5timer.c H5trace.c \
         H5EA.c H5EAcache.c H5EAdbg.c H5EAdblkpage.c H5EAdblock.c H5EAhdr.c \
         H5EAiblock.c H5EAint.c H5EAsblock.c H5EAstat.c H5EAtest.c \
         H5F.c H5Faccum.c H5Fdbg.c H5Ffake.c H5Fio.c H5Fmount.c H5Fmpi.c H5Fquery.c \
-        H5Fsfile.c H5Fsuper.c H5Ftest.c \
+        H5Fsfile.c H5Fsuper.c H5Fsuper_cache.c H5Ftest.c \
         H5FA.c H5FAcache.c H5FAdbg.c H5FAdblock.c H5FAdblkpage.c H5FAhdr.c \
         H5FAstat.c H5FAtest.c \
         H5FD.c H5FDcore.c  \
@@ -736,6 +737,7 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5Fquery.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5Fsfile.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5Fsuper.Plo@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5Fsuper_cache.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5Ftest.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5G.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5Gbtree2.Plo@am__quote@
diff --git a/test/tfile.c b/test/tfile.c
index 2116a2c..07ccfb2 100644
--- a/test/tfile.c
+++ b/test/tfile.c
@@ -1351,7 +1351,7 @@ test_file_ishdf5(void)
 
     /* Create non-HDF5 file and check it */
     fd=HDopen(FILE1, O_RDWR|O_CREAT|O_TRUNC, 0666);
-    CHECK(ret, FAIL, "HDopen");
+    CHECK(fd, FAIL, "HDopen");
 
     /* Initialize information to write */
     for(u=0; u<1024; u++)
@@ -2026,6 +2026,59 @@ test_cached_stab_info(void)
 
 /****************************************************************
 **
+**  test_rw_noupdate(): low-level file test routine.
+**      This test checks to ensure that opening and closing a file 
+**      with read/write permissions does not write anything to the 
+**      file if the file does not change.
+**
+**  Programmer: Mike McGreevy
+**              mamcgree@hdfgroup.org
+**              June 29, 2009
+**
+*****************************************************************/
+static void
+test_rw_noupdate(void)
+{
+    hid_t file_id;      /* HDF5 File ID */
+    h5_stat_t sb1, sb2; /* Info from 'stat' call */
+    double diff;        /* Difference in modification times */
+    herr_t ret;         /* Generic return value */
+
+    /* Output message about test being performed */
+    MESSAGE(5, ("Testing to verify that nothing is written if nothing is changed.\n"));
+
+    /* Create and Close File */
+    file_id = H5Fcreate(FILE1, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
+    CHECK(file_id, FAIL, "H5Fcreate");
+    ret = H5Fclose(file_id);
+    CHECK(ret, FAIL, "H5Fclose");
+
+    /* Determine File's Initial Timestamp */
+    ret = HDstat(FILE1, &sb1);
+    VERIFY(ret, 0, "HDfstat");
+
+    /* Wait for 2 seconds */
+    /* This ensures a system time difference between the two file accesses */
+    HDsleep(2);
+
+    /* Open and Close File With Read/Write Permission */
+    file_id = H5Fopen(FILE1, H5F_ACC_RDWR, H5P_DEFAULT);
+    CHECK(file_id, FAIL, "H5Fopen");
+    ret = H5Fclose(file_id);
+    CHECK(ret, FAIL, "H5Fclose");
+
+    /* Determine File's New Timestamp */
+    ret = HDstat(FILE1, &sb2);
+    VERIFY(ret, 0, "HDstat");
+
+    /* Ensure That Timestamps Are Equal */
+    diff = HDdifftime(sb2.st_mtime, sb1.st_mtime);
+    ret = (diff > 0.0);
+    VERIFY(ret, 0, "Timestamp");
+} /* end test_rw_noupdate() */
+
+/****************************************************************
+**
 **  test_file(): Main low-level file I/O test routine.
 **
 ****************************************************************/
@@ -2057,6 +2110,7 @@ test_file(void)
 #endif /*H5_CANNOT_OPEN_TWICE*/
     test_userblock_file_size(); /* Tests that files created with a userblock have the correct size */
     test_cached_stab_info();    /* Tests that files are created with cached stab info in the superblock */
+    test_rw_noupdate();         /* Test to ensure that RW permissions don't write the file unless dirtied */
 } /* test_file() */
 
 
diff --git a/testpar/t_cache.c b/testpar/t_cache.c
index 0b94170..4e1e5ba 100644
--- a/testpar/t_cache.c
+++ b/testpar/t_cache.c
@@ -704,6 +704,10 @@ addr_to_datum_index(haddr_t base_addr)
  *		JRM -- 2/4/09
  *		Added initialization for the cleared and flushed fields.
  *
+ *              Mike McGreevy, July 2, 2009
+ *              Changed base address from 0 to 512 since the superblock will
+ *              always be at address 0.
+ *
  *****************************************************************************/
 
 static void
@@ -724,7 +728,7 @@ init_data(void)
                                       1974, 3194, 5168, 8362, 13539};
     int i;
     int j = 0;
-    haddr_t addr = 0;
+    haddr_t addr = 512;
 
     /* this must hold so renames don't change entry size. */
     HDassert( (NUM_DATA_ENTRIES / 2) % 20 == 0 );
diff --git a/tools/h5copy/testfiles/h5copytst.out.ls b/tools/h5copy/testfiles/h5copytst.out.ls
index 9cad76f..5ff1e90 100644
--- a/tools/h5copy/testfiles/h5copytst.out.ls
+++ b/tools/h5copy/testfiles/h5copytst.out.ls
@@ -6,57 +6,57 @@ Opened "../testfiles/h5copytst.out.h5" with sec2 driver.
     Location:  1:96
     Links:     1
 /A                       Group
-    Location:  1:89936
+    Location:  1:90032
     Links:     1
 /A/B1                    Group
-    Location:  1:90640
+    Location:  1:90736
     Links:     1
 /A/B1/simple             Dataset {6/6}
-    Location:  1:89808
+    Location:  1:89904
     Links:     1
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /A/B2                    Group
-    Location:  1:94176
+    Location:  1:94272
     Links:     1
 /A/B2/simple2            Dataset {6/6}
-    Location:  1:94048
+    Location:  1:94144
     Links:     1
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /C                       Group
-    Location:  1:97384
+    Location:  1:97480
     Links:     1
 /C/D                     Group
-    Location:  1:98088
+    Location:  1:98184
     Links:     1
 /C/D/simple              Dataset {6/6}
-    Location:  1:97256
+    Location:  1:97352
     Links:     1
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /E                       Group
-    Location:  1:112000
+    Location:  1:112096
     Links:     1
 /E/F                     Group
-    Location:  1:112704
+    Location:  1:112800
     Links:     1
 /E/F/grp_dsets           Group
-    Location:  1:100200
+    Location:  1:100296
     Links:     1
 /E/F/grp_dsets/chunk     Dataset {6/6}
-    Location:  1:104384
+    Location:  1:104480
     Links:     1
     Chunks:    {2} 8 bytes
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /E/F/grp_dsets/compact   Dataset {6/6}
-    Location:  1:104840
+    Location:  1:104936
     Links:     1
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /E/F/grp_dsets/compound  Dataset {2/2}
-    Location:  1:104976
+    Location:  1:105072
     Links:     1
     Storage:   <details removed for portability>
     Type:      struct {
@@ -64,60 +64,60 @@ Opened "../testfiles/h5copytst.out.h5" with sec2 driver.
                    "str2"             +20   20-byte null-terminated ASCII string
                } 40 bytes
 /E/F/grp_dsets/compressed Dataset {6/6}
-    Location:  1:107288
+    Location:  1:107384
     Links:     1
     Chunks:    {2} 8 bytes
     Storage:   <details removed for portability>
     Filter-0:  deflate-1 OPT {1}
     Type:      32-bit little-endian integer
 /E/F/grp_dsets/named_vl  Dataset {2/2}
-    Location:  1:111600
+    Location:  1:111696
     Links:     1
     Storage:   <details removed for portability>
-    Type:      shared-1:107456 variable length of
+    Type:      shared-1:107552 variable length of
                    32-bit little-endian integer
 /E/F/grp_dsets/nested_vl Dataset {2/2}
-    Location:  1:111728
+    Location:  1:111824
     Links:     1
     Storage:   <details removed for portability>
     Type:      variable length of
                    variable length of
                        32-bit little-endian integer
 /E/F/grp_dsets/simple    Dataset {6/6}
-    Location:  1:111872
+    Location:  1:111968
     Links:     1
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /E/F/grp_dsets/vl        Type
-    Location:  1:107456
+    Location:  1:107552
     Links:     2
-    Type:      shared-1:107456 variable length of
+    Type:      shared-1:107552 variable length of
                    32-bit little-endian integer
 /G                       Group
-    Location:  1:127648
+    Location:  1:127744
     Links:     1
 /G/H                     Group
-    Location:  1:128352
+    Location:  1:128448
     Links:     1
 /G/H/grp_nested          Group
-    Location:  1:114728
+    Location:  1:114824
     Links:     1
 /G/H/grp_nested/grp_dsets Group
-    Location:  1:115520
+    Location:  1:115616
     Links:     1
 /G/H/grp_nested/grp_dsets/chunk Dataset {6/6}
-    Location:  1:119704
+    Location:  1:119800
     Links:     1
     Chunks:    {2} 8 bytes
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /G/H/grp_nested/grp_dsets/compact Dataset {6/6}
-    Location:  1:120160
+    Location:  1:120256
     Links:     1
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /G/H/grp_nested/grp_dsets/compound Dataset {2/2}
-    Location:  1:120296
+    Location:  1:120392
     Links:     1
     Storage:   <details removed for portability>
     Type:      struct {
@@ -125,48 +125,48 @@ Opened "../testfiles/h5copytst.out.h5" with sec2 driver.
                    "str2"             +20   20-byte null-terminated ASCII string
                } 40 bytes
 /G/H/grp_nested/grp_dsets/compressed Dataset {6/6}
-    Location:  1:122608
+    Location:  1:122704
     Links:     1
     Chunks:    {2} 8 bytes
     Storage:   <details removed for portability>
     Filter-0:  deflate-1 OPT {1}
     Type:      32-bit little-endian integer
 /G/H/grp_nested/grp_dsets/named_vl Dataset {2/2}
-    Location:  1:126920
+    Location:  1:127016
     Links:     1
     Storage:   <details removed for portability>
-    Type:      shared-1:122776 variable length of
+    Type:      shared-1:122872 variable length of
                    32-bit little-endian integer
 /G/H/grp_nested/grp_dsets/nested_vl Dataset {2/2}
-    Location:  1:127048
+    Location:  1:127144
     Links:     1
     Storage:   <details removed for portability>
     Type:      variable length of
                    variable length of
                        32-bit little-endian integer
 /G/H/grp_nested/grp_dsets/simple Dataset {6/6}
-    Location:  1:127192
+    Location:  1:127288
     Links:     1
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /G/H/grp_nested/grp_dsets/vl Type
-    Location:  1:122776
+    Location:  1:122872
     Links:     2
-    Type:      shared-1:122776 variable length of
+    Type:      shared-1:122872 variable length of
                    32-bit little-endian integer
 /chunk                   Dataset {6/6}
-    Location:  1:6216
+    Location:  1:6312
     Links:     1
     Chunks:    {2} 8 bytes
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /compact                 Dataset {6/6}
-    Location:  1:6344
+    Location:  1:6440
     Links:     1
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /compound                Dataset {2/2}
-    Location:  1:8528
+    Location:  1:8624
     Links:     1
     Storage:   <details removed for portability>
     Type:      struct {
@@ -174,28 +174,28 @@ Opened "../testfiles/h5copytst.out.h5" with sec2 driver.
                    "str2"             +20   20-byte null-terminated ASCII string
                } 40 bytes
 /compressed              Dataset {6/6}
-    Location:  1:12888
+    Location:  1:12984
     Links:     1
     Chunks:    {2} 8 bytes
     Storage:   <details removed for portability>
     Filter-0:  deflate-1 OPT {1}
     Type:      32-bit little-endian integer
 /grp_dsets               Group
-    Location:  1:33760
+    Location:  1:33856
     Links:     1
 /grp_dsets/chunk         Dataset {6/6}
-    Location:  1:37944
+    Location:  1:38040
     Links:     1
     Chunks:    {2} 8 bytes
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /grp_dsets/compact       Dataset {6/6}
-    Location:  1:38400
+    Location:  1:38496
     Links:     1
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /grp_dsets/compound      Dataset {2/2}
-    Location:  1:38536
+    Location:  1:38632
     Links:     1
     Storage:   <details removed for portability>
     Type:      struct {
@@ -203,62 +203,62 @@ Opened "../testfiles/h5copytst.out.h5" with sec2 driver.
                    "str2"             +20   20-byte null-terminated ASCII string
                } 40 bytes
 /grp_dsets/compressed    Dataset {6/6}
-    Location:  1:40848
+    Location:  1:40944
     Links:     1
     Chunks:    {2} 8 bytes
     Storage:   <details removed for portability>
     Filter-0:  deflate-1 OPT {1}
     Type:      32-bit little-endian integer
 /grp_dsets/named_vl      Dataset {2/2}
-    Location:  1:45160
+    Location:  1:45256
     Links:     1
     Storage:   <details removed for portability>
-    Type:      shared-1:41016 variable length of
+    Type:      shared-1:41112 variable length of
                    32-bit little-endian integer
 /grp_dsets/nested_vl     Dataset {2/2}
-    Location:  1:45288
+    Location:  1:45384
     Links:     1
     Storage:   <details removed for portability>
     Type:      variable length of
                    variable length of
                        32-bit little-endian integer
 /grp_dsets/simple        Dataset {6/6}
-    Location:  1:45432
+    Location:  1:45528
     Links:     1
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /grp_dsets/simple_group  Dataset {6/6}
-    Location:  1:61544
+    Location:  1:61640
     Links:     1
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /grp_dsets/vl            Type
-    Location:  1:41016
+    Location:  1:41112
     Links:     2
-    Type:      shared-1:41016 variable length of
+    Type:      shared-1:41112 variable length of
                    32-bit little-endian integer
 /grp_empty               Group
-    Location:  1:32968
+    Location:  1:33064
     Links:     1
 /grp_nested              Group
-    Location:  1:46224
+    Location:  1:46320
     Links:     1
 /grp_nested/grp_dsets    Group
-    Location:  1:47016
+    Location:  1:47112
     Links:     1
 /grp_nested/grp_dsets/chunk Dataset {6/6}
-    Location:  1:51200
+    Location:  1:51296
     Links:     1
     Chunks:    {2} 8 bytes
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /grp_nested/grp_dsets/compact Dataset {6/6}
-    Location:  1:51656
+    Location:  1:51752
     Links:     1
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /grp_nested/grp_dsets/compound Dataset {2/2}
-    Location:  1:51792
+    Location:  1:51888
     Links:     1
     Storage:   <details removed for portability>
     Type:      struct {
@@ -266,51 +266,51 @@ Opened "../testfiles/h5copytst.out.h5" with sec2 driver.
                    "str2"             +20   20-byte null-terminated ASCII string
                } 40 bytes
 /grp_nested/grp_dsets/compressed Dataset {6/6}
-    Location:  1:54104
+    Location:  1:54200
     Links:     1
     Chunks:    {2} 8 bytes
     Storage:   <details removed for portability>
     Filter-0:  deflate-1 OPT {1}
     Type:      32-bit little-endian integer
 /grp_nested/grp_dsets/named_vl Dataset {2/2}
-    Location:  1:58416
+    Location:  1:58512
     Links:     1
     Storage:   <details removed for portability>
-    Type:      shared-1:54272 variable length of
+    Type:      shared-1:54368 variable length of
                    32-bit little-endian integer
 /grp_nested/grp_dsets/nested_vl Dataset {2/2}
-    Location:  1:58544
+    Location:  1:58640
     Links:     1
     Storage:   <details removed for portability>
     Type:      variable length of
                    variable length of
                        32-bit little-endian integer
 /grp_nested/grp_dsets/simple Dataset {6/6}
-    Location:  1:58688
+    Location:  1:58784
     Links:     1
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /grp_nested/grp_dsets/vl Type
-    Location:  1:54272
+    Location:  1:54368
     Links:     2
-    Type:      shared-1:54272 variable length of
+    Type:      shared-1:54368 variable length of
                    32-bit little-endian integer
 /grp_rename              Group
-    Location:  1:62752
+    Location:  1:62848
     Links:     1
 /grp_rename/chunk        Dataset {6/6}
-    Location:  1:66936
+    Location:  1:67032
     Links:     1
     Chunks:    {2} 8 bytes
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /grp_rename/compact      Dataset {6/6}
-    Location:  1:67392
+    Location:  1:67488
     Links:     1
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /grp_rename/compound     Dataset {2/2}
-    Location:  1:67528
+    Location:  1:67624
     Links:     1
     Storage:   <details removed for portability>
     Type:      struct {
@@ -318,28 +318,28 @@ Opened "../testfiles/h5copytst.out.h5" with sec2 driver.
                    "str2"             +20   20-byte null-terminated ASCII string
                } 40 bytes
 /grp_rename/compressed   Dataset {6/6}
-    Location:  1:69840
+    Location:  1:69936
     Links:     1
     Chunks:    {2} 8 bytes
     Storage:   <details removed for portability>
     Filter-0:  deflate-1 OPT {1}
     Type:      32-bit little-endian integer
 /grp_rename/grp_dsets    Group
-    Location:  1:75632
+    Location:  1:75728
     Links:     1
 /grp_rename/grp_dsets/chunk Dataset {6/6}
-    Location:  1:79816
+    Location:  1:79912
     Links:     1
     Chunks:    {2} 8 bytes
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /grp_rename/grp_dsets/compact Dataset {6/6}
-    Location:  1:80272
+    Location:  1:80368
     Links:     1
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /grp_rename/grp_dsets/compound Dataset {2/2}
-    Location:  1:80408
+    Location:  1:80504
     Links:     1
     Storage:   <details removed for portability>
     Type:      struct {
@@ -347,73 +347,73 @@ Opened "../testfiles/h5copytst.out.h5" with sec2 driver.
                    "str2"             +20   20-byte null-terminated ASCII string
                } 40 bytes
 /grp_rename/grp_dsets/compressed Dataset {6/6}
-    Location:  1:82720
+    Location:  1:82816
     Links:     1
     Chunks:    {2} 8 bytes
     Storage:   <details removed for portability>
     Filter-0:  deflate-1 OPT {1}
     Type:      32-bit little-endian integer
 /grp_rename/grp_dsets/named_vl Dataset {2/2}
-    Location:  1:87032
+    Location:  1:87128
     Links:     1
     Storage:   <details removed for portability>
-    Type:      shared-1:82888 variable length of
+    Type:      shared-1:82984 variable length of
                    32-bit little-endian integer
 /grp_rename/grp_dsets/nested_vl Dataset {2/2}
-    Location:  1:87160
+    Location:  1:87256
     Links:     1
     Storage:   <details removed for portability>
     Type:      variable length of
                    variable length of
                        32-bit little-endian integer
 /grp_rename/grp_dsets/simple Dataset {6/6}
-    Location:  1:87304
+    Location:  1:87400
     Links:     1
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /grp_rename/grp_dsets/vl Type
-    Location:  1:82888
+    Location:  1:82984
     Links:     2
-    Type:      shared-1:82888 variable length of
+    Type:      shared-1:82984 variable length of
                    32-bit little-endian integer
 /grp_rename/named_vl     Dataset {2/2}
-    Location:  1:74152
+    Location:  1:74248
     Links:     1
     Storage:   <details removed for portability>
-    Type:      shared-1:70008 variable length of
+    Type:      shared-1:70104 variable length of
                    32-bit little-endian integer
 /grp_rename/nested_vl    Dataset {2/2}
-    Location:  1:74280
+    Location:  1:74376
     Links:     1
     Storage:   <details removed for portability>
     Type:      variable length of
                    variable length of
                        32-bit little-endian integer
 /grp_rename/simple       Dataset {6/6}
-    Location:  1:74424
+    Location:  1:74520
     Links:     1
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /grp_rename/vl           Type
-    Location:  1:70008
+    Location:  1:70104
     Links:     2
-    Type:      shared-1:70008 variable length of
+    Type:      shared-1:70104 variable length of
                    32-bit little-endian integer
 /named_vl                Dataset {2/2}
-    Location:  1:13104
+    Location:  1:13200
     Links:     1
     Storage:   <details removed for portability>
-    Type:      shared-1:13056 variable length of
+    Type:      shared-1:13152 variable length of
                    32-bit little-endian integer
 /nested_vl               Dataset {2/2}
-    Location:  1:27392
+    Location:  1:27488
     Links:     1
     Storage:   <details removed for portability>
     Type:      variable length of
                    variable length of
                        32-bit little-endian integer
 /rename                  Dataset {2/2}
-    Location:  1:31760
+    Location:  1:31856
     Links:     1
     Storage:   <details removed for portability>
     Type:      struct {
@@ -426,7 +426,7 @@ Opened "../testfiles/h5copytst.out.h5" with sec2 driver.
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer
 /simple_top              Dataset {6/6}
-    Location:  1:29584
+    Location:  1:29680
     Links:     1
     Storage:   <details removed for portability>
     Type:      32-bit little-endian integer