[svn-r17786] Description:

	Bring r17749 & 17785 from trunk to 1.8 branch:

17749:
	Refactor v2 B-tree code to bring it further in line with how the fractal
heap code works, to make forthcoming modificaions easier.  Also minor tweaks to
the fractal heap code to clean it up a bit more also.

17785:
	Further refactor v2 B-tree code to bring it closer to modern data
structure designed in the library, mainly by introducing a H5B2_t type so that
the v2 B-tree could be held open, but not require the B-tree header to be
protected the whole time.  A few other minor tweaks as well.

	Also, remove unused 'dirty' flag from fractal heap header.

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 (jam) w/PGI compilers, w/default API=1.8.x,
                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 debug mode
        Linux/64-amd64 2.6 (abe) w/parallel, w/FORTRAN, in production mode
        Mac OS X/32 10.6.1 (amazon) in debug mode
        Mac OS X/32 10.6.1 (amazon) w/C++ & FORTRAN, w/threadsafe,
                in production mode

1 files changed, 295 insertions, 178 deletions

diff --git a/src/H5B2.c b/src/H5B2.c
index e15c11e..a30a6e2 100644
--- a/src/H5B2.c
+++ b/src/H5B2.c
@@ -41,7 +41,6 @@
 #include "H5private.h"		/* Generic Functions			*/
 #include "H5B2pkg.h"		/* v2 B-trees				*/
 #include "H5Eprivate.h"		/* Error handling		  	*/
-#include "H5MFprivate.h"	/* File memory management		*/
 
 
 /****************/
@@ -62,18 +61,15 @@
 /********************/
 /* Local Prototypes */
 /********************/
-static H5B2_hdr_t *H5B2_open(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type,
-    haddr_t addr, H5AC_protect_t rw);
-static herr_t H5B2_close(H5B2_hdr_t *hdr, hid_t dxpl_id);
+static H5B2_t *H5B2_open(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *cls,
+    haddr_t addr);
+static herr_t H5B2_close(H5B2_t *bt2, hid_t dxpl_id);
 
 
 /*********************/
 /* Package Variables */
 /*********************/
 
-/* Declare a free list to manage the H5B2_hdr_t struct */
-H5FL_DEFINE(H5B2_hdr_t);
-
 
 /*****************************/
 /* Library Private Variables */
@@ -84,6 +80,10 @@ H5FL_DEFINE(H5B2_hdr_t);
 /* Local Variables */
 /*******************/
 
+/* Declare a free list to manage the H5B2_t struct */
+H5FL_DEFINE_STATIC(H5B2_t);
+
+
 
 /*-------------------------------------------------------------------------
  * Function:	H5B2_create
@@ -103,7 +103,7 @@ herr_t
 H5B2_create(H5F_t *f, hid_t dxpl_id, const H5B2_create_t *cparam,
     haddr_t *addr_p)
 {
-    H5B2_hdr_t *hdr = NULL;             /* The new B-tree header information */
+    haddr_t hdr_addr;                   /* The new v2 B-tree header address */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI(H5B2_create, FAIL)
@@ -115,36 +115,14 @@ H5B2_create(H5F_t *f, hid_t dxpl_id, const H5B2_create_t *cparam,
     HDassert(cparam);
     HDassert(addr_p);
 
-    /*
-     * Allocate file and memory data structures.
-     */
-    if(NULL == (hdr = H5FL_CALLOC(H5B2_hdr_t)))
-	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for B-tree header")
-
-    /* Assign non-zero information */
-    hdr->root.addr = HADDR_UNDEF;
-
-    /* Initialize shared B-tree info */
-    if(H5B2_hdr_init(f, hdr, cparam, 0) < 0)
-	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't create shared B-tree info")
-
-    /* Allocate space for the header on disk */
-    if(HADDR_UNDEF == (hdr->addr = H5MF_alloc(f, H5FD_MEM_BTREE, dxpl_id, (hsize_t)H5B2_HEADER_SIZE(f))))
-	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "file allocation failed for B-tree header")
-
-    /* Cache the new B-tree node */
-    if(H5AC_set(f, dxpl_id, H5AC_BT2_HDR, hdr->addr, hdr, H5AC__NO_FLAGS_SET) < 0)
-	HGOTO_ERROR(H5E_BTREE, H5E_CANTINIT, FAIL, "can't add B-tree header to cache")
+    /* Create shared v2 B-tree header */
+    if(HADDR_UNDEF == (hdr_addr = H5B2_hdr_create(f, dxpl_id, cparam)))
+	HGOTO_ERROR(H5E_BTREE, H5E_CANTINIT, FAIL, "can't create v2 B-tree header")
 
     /* Set the B-tree's address to return */
-    *addr_p = hdr->addr;
+    *addr_p = hdr_addr;
 
 done:
-    if(ret_value < 0) {
-	if(hdr)
-            (void)H5B2_cache_hdr_dest(f, hdr);
-    } /* end if */
-
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5B2_create() */
 
@@ -163,35 +141,53 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-static H5B2_hdr_t *
-H5B2_open(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
-    H5AC_protect_t rw)
+static H5B2_t *
+H5B2_open(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *cls, haddr_t addr)
 {
+    H5B2_t	*bt2 = NULL;            /* Pointer to the B-tree */
     H5B2_hdr_t	*hdr = NULL;            /* Pointer to the B-tree header */
-    H5B2_hdr_t	*ret_value;             /* Return value */
+    H5B2_t	*ret_value;             /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT(H5B2_open)
 
     /* Check arguments. */
     HDassert(f);
-    HDassert(type);
+    HDassert(cls);
     HDassert(H5F_addr_defined(addr));
 
     /* Look up the B-tree header */
-    if(NULL == (hdr = (H5B2_hdr_t *)H5AC_protect(f, dxpl_id, H5AC_BT2_HDR, addr, type, NULL, rw)))
+    if(NULL == (hdr = (H5B2_hdr_t *)H5AC_protect(f, dxpl_id, H5AC_BT2_HDR, addr, cls, NULL, H5AC_READ)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTPROTECT, NULL, "unable to load B-tree header")
 
-    /* Set file pointer for this B-tree operation */
-    hdr->f = f;
+    /* Check for pending heap deletion */
+    if(hdr->pending_delete)
+        HGOTO_ERROR(H5E_BTREE, H5E_CANTOPENOBJ, NULL, "can't open v2 B-tree pending deletion")
+
+    /* Create v2 B-tree info */
+    if(NULL == (bt2 = H5FL_MALLOC(H5B2_t)))
+        HGOTO_ERROR(H5E_BTREE, H5E_CANTALLOC, NULL, "memory allocation failed for v2 B-tree info")
+
+    /* Point v2 B-tree wrapper at header */
+    bt2->hdr = hdr;
+    if(H5B2_hdr_incr(bt2->hdr) < 0)
+        HGOTO_ERROR(H5E_BTREE, H5E_CANTINC, NULL, "can't increment reference count on shared v2 B-tree header")
+
+    /* Increment # of files using this v2 B-tree header */
+    if(H5B2_hdr_fuse_incr(bt2->hdr) < 0)
+	HGOTO_ERROR(H5E_BTREE, H5E_CANTINC, NULL, "can't increment file reference count on shared v2 B-tree header")
+
+    /* Set file pointer for this v2 B-tree open context */
+    bt2->f = f;
 
     /* Set the return value */
-    ret_value = hdr;
+    ret_value = bt2;
 
 done:
-    if(!ret_value) {
-        if(hdr && H5B2_close(hdr, dxpl_id) < 0)
-            HDONE_ERROR(H5E_BTREE, H5E_CANTCLOSEOBJ, NULL, "unable to close B-tree")
-    } /* end if */
+    if(hdr && H5AC_unprotect(f, dxpl_id, H5AC_BT2_HDR, addr, hdr, H5AC__NO_FLAGS_SET) < 0)
+        HDONE_ERROR(H5E_BTREE, H5E_CANTUNPROTECT, NULL, "unable to release v2 B-tree header")
+    if(!ret_value && bt2) 
+        if(H5B2_close(bt2, dxpl_id) < 0)
+            HDONE_ERROR(H5E_BTREE, H5E_CANTCLOSEOBJ, NULL, "unable to close v2 B-tree")
 
     FUNC_LEAVE_NOAPI(ret_value)
 } /* H5B2_open() */
@@ -211,23 +207,30 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5B2_insert(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
+H5B2_insert(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *cls, haddr_t addr,
            void *udata)
 {
-    H5B2_hdr_t	*hdr = NULL;            /* Pointer to the B-tree header */
+    H5B2_t	*bt2 = NULL;            /* Pointer to the B-tree */
+    H5B2_hdr_t	*hdr;                   /* Pointer to the B-tree header */
     herr_t	ret_value = SUCCEED;    /* Return value */
 
     FUNC_ENTER_NOAPI(H5B2_insert, FAIL)
 
     /* Check arguments. */
     HDassert(f);
-    HDassert(type);
+    HDassert(cls);
     HDassert(H5F_addr_defined(addr));
 
-    /* Open the B-tree header */
-    if(NULL == (hdr = H5B2_open(f, dxpl_id, type, addr, H5AC_WRITE)))
+    /* Open the B-tree */
+    if(NULL == (bt2 = H5B2_open(f, dxpl_id, cls, addr)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTOPENOBJ, FAIL, "unable to open B-tree")
 
+    /* Set the shared v2 B-tree header's file context for this operation */
+    bt2->hdr->f = bt2->f;
+
+    /* Get the v2 B-tree header */
+    hdr = bt2->hdr;
+
     /* Check if the root node is allocated yet */
     if(!H5F_addr_defined(hdr->root.addr)) {
         /* Create root node as leaf node in B-tree */
@@ -257,7 +260,7 @@ H5B2_insert(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
 
 done:
     /* Close the B-tree */
-    if(hdr && H5B2_close(hdr, dxpl_id) < 0)
+    if(bt2 && H5B2_close(bt2, dxpl_id) < 0)
         HDONE_ERROR(H5E_BTREE, H5E_CANTCLOSEOBJ, FAIL, "unable to close B-tree")
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -282,24 +285,31 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5B2_iterate(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
+H5B2_iterate(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *cls, haddr_t addr,
     H5B2_operator_t op, void *op_data)
 {
-    H5B2_hdr_t	*hdr = NULL;            /* Pointer to the B-tree header */
+    H5B2_t	*bt2 = NULL;            /* Pointer to the B-tree */
+    H5B2_hdr_t	*hdr;                   /* Pointer to the B-tree header */
     herr_t	ret_value = SUCCEED;    /* Return value */
 
     FUNC_ENTER_NOAPI(H5B2_iterate, FAIL)
 
     /* Check arguments. */
     HDassert(f);
-    HDassert(type);
+    HDassert(cls);
     HDassert(H5F_addr_defined(addr));
     HDassert(op);
 
-    /* Open the B-tree header */
-    if(NULL == (hdr = H5B2_open(f, dxpl_id, type, addr, H5AC_READ)))
+    /* Open the B-tree */
+    if(NULL == (bt2 = H5B2_open(f, dxpl_id, cls, addr)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTOPENOBJ, FAIL, "unable to open B-tree")
 
+    /* Set the shared v2 B-tree header's file context for this operation */
+    bt2->hdr->f = bt2->f;
+
+    /* Get the v2 B-tree header */
+    hdr = bt2->hdr;
+
     /* Iterate through records */
     if(hdr->root.node_nrec > 0) {
         /* Iterate through nodes */
@@ -309,7 +319,7 @@ H5B2_iterate(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
 
 done:
     /* Close the B-tree */
-    if(hdr && H5B2_close(hdr, dxpl_id) < 0)
+    if(bt2 && H5B2_close(bt2, dxpl_id) < 0)
         HDONE_ERROR(H5E_BTREE, H5E_CANTCLOSEOBJ, FAIL, "unable to close B-tree")
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -340,10 +350,11 @@ done:
  *-------------------------------------------------------------------------
  */
 htri_t
-H5B2_find(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
+H5B2_find(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *cls, haddr_t addr,
     void *udata, H5B2_found_t op, void *op_data)
 {
-    H5B2_hdr_t	*hdr = NULL;            /* Pointer to the B-tree header */
+    H5B2_t	*bt2 = NULL;            /* Pointer to the B-tree */
+    H5B2_hdr_t	*hdr;                   /* Pointer to the B-tree header */
     H5B2_node_ptr_t curr_node_ptr;      /* Node pointer info for current node */
     unsigned    depth;                  /* Current depth of the tree */
     int         cmp;                    /* Comparison value of records */
@@ -354,13 +365,19 @@ H5B2_find(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
 
     /* Check arguments. */
     HDassert(f);
-    HDassert(type);
+    HDassert(cls);
     HDassert(H5F_addr_defined(addr));
 
-    /* Open the B-tree header */
-    if(NULL == (hdr = H5B2_open(f, dxpl_id, type, addr, H5AC_READ)))
+    /* Open the B-tree */
+    if(NULL == (bt2 = H5B2_open(f, dxpl_id, cls, addr)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTOPENOBJ, FAIL, "unable to open B-tree")
 
+    /* Set the shared v2 B-tree header's file context for this operation */
+    bt2->hdr->f = bt2->f;
+
+    /* Get the v2 B-tree header */
+    hdr = bt2->hdr;
+
     /* Make copy of the root node pointer to start search with */
     curr_node_ptr = hdr->root;
 
@@ -455,7 +472,7 @@ H5B2_find(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
 
 done:
     /* Close the B-tree */
-    if(hdr && H5B2_close(hdr, dxpl_id) < 0)
+    if(bt2 && H5B2_close(bt2, dxpl_id) < 0)
         HDONE_ERROR(H5E_BTREE, H5E_CANTCLOSEOBJ, FAIL, "unable to close B-tree")
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -481,10 +498,11 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5B2_index(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
+H5B2_index(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *cls, haddr_t addr,
     H5_iter_order_t order, hsize_t idx, H5B2_found_t op, void *op_data)
 {
-    H5B2_hdr_t	*hdr = NULL;            /* Pointer to the B-tree header */
+    H5B2_t	*bt2 = NULL;            /* Pointer to the B-tree */
+    H5B2_hdr_t	*hdr;                   /* Pointer to the B-tree header */
     H5B2_node_ptr_t curr_node_ptr;      /* Node pointer info for current node */
     unsigned    depth;                  /* Current depth of the tree */
     herr_t	ret_value = SUCCEED;    /* Return value */
@@ -493,14 +511,20 @@ H5B2_index(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
 
     /* Check arguments. */
     HDassert(f);
-    HDassert(type);
+    HDassert(cls);
     HDassert(H5F_addr_defined(addr));
     HDassert(op);
 
-    /* Open the B-tree header */
-    if(NULL == (hdr = H5B2_open(f, dxpl_id, type, addr, H5AC_READ)))
+    /* Open the B-tree */
+    if(NULL == (bt2 = H5B2_open(f, dxpl_id, cls, addr)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTOPENOBJ, FAIL, "unable to open B-tree")
 
+    /* Set the shared v2 B-tree header's file context for this operation */
+    bt2->hdr->f = bt2->f;
+
+    /* Get the v2 B-tree header */
+    hdr = bt2->hdr;
+
     /* Make copy of the root node pointer to start search with */
     curr_node_ptr = hdr->root;
 
@@ -620,7 +644,7 @@ H5B2_index(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
 
 done:
     /* Close the B-tree */
-    if(hdr && H5B2_close(hdr, dxpl_id) < 0)
+    if(bt2 && H5B2_close(bt2, dxpl_id) < 0)
         HDONE_ERROR(H5E_BTREE, H5E_CANTCLOSEOBJ, FAIL, "unable to close B-tree")
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -641,23 +665,30 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5B2_remove(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
+H5B2_remove(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *cls, haddr_t addr,
     void *udata, H5B2_remove_t op, void *op_data)
 {
-    H5B2_hdr_t	*hdr = NULL;            /* Pointer to the B-tree header */
+    H5B2_t	*bt2 = NULL;            /* Pointer to the B-tree */
+    H5B2_hdr_t	*hdr;                   /* Pointer to the B-tree header */
     herr_t	ret_value = SUCCEED;    /* Return value */
 
     FUNC_ENTER_NOAPI(H5B2_remove, FAIL)
 
     /* Check arguments. */
     HDassert(f);
-    HDassert(type);
+    HDassert(cls);
     HDassert(H5F_addr_defined(addr));
 
-    /* Open the B-tree header */
-    if(NULL == (hdr = H5B2_open(f, dxpl_id, type, addr, H5AC_WRITE)))
+    /* Open the B-tree */
+    if(NULL == (bt2 = H5B2_open(f, dxpl_id, cls, addr)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTOPENOBJ, FAIL, "unable to open B-tree")
 
+    /* Set the shared v2 B-tree header's file context for this operation */
+    bt2->hdr->f = bt2->f;
+
+    /* Get the v2 B-tree header */
+    hdr = bt2->hdr;
+
     /* Check for empty B-tree */
     if(0 == hdr->root.all_nrec)
         HGOTO_ERROR(H5E_BTREE, H5E_NOTFOUND, FAIL, "record is not in B-tree")
@@ -697,7 +728,7 @@ H5B2_remove(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
 
 done:
     /* Close the B-tree */
-    if(hdr && H5B2_close(hdr, dxpl_id) < 0)
+    if(bt2 && H5B2_close(bt2, dxpl_id) < 0)
         HDONE_ERROR(H5E_BTREE, H5E_CANTCLOSEOBJ, FAIL, "unable to close B-tree")
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -718,24 +749,31 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5B2_remove_by_idx(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type,
+H5B2_remove_by_idx(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *cls,
     haddr_t addr, H5_iter_order_t order, hsize_t idx, H5B2_remove_t op,
     void *op_data)
 {
-    H5B2_hdr_t	*hdr = NULL;            /* Pointer to the B-tree header */
+    H5B2_t	*bt2 = NULL;            /* Pointer to the B-tree */
+    H5B2_hdr_t	*hdr;                   /* Pointer to the B-tree header */
     herr_t	ret_value = SUCCEED;    /* Return value */
 
     FUNC_ENTER_NOAPI(H5B2_remove_by_idx, FAIL)
 
     /* Check arguments. */
     HDassert(f);
-    HDassert(type);
+    HDassert(cls);
     HDassert(H5F_addr_defined(addr));
 
-    /* Open the B-tree header */
-    if(NULL == (hdr = H5B2_open(f, dxpl_id, type, addr, H5AC_WRITE)))
+    /* Open the B-tree */
+    if(NULL == (bt2 = H5B2_open(f, dxpl_id, cls, addr)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTOPENOBJ, FAIL, "unable to open B-tree")
 
+    /* Set the shared v2 B-tree header's file context for this operation */
+    bt2->hdr->f = bt2->f;
+
+    /* Get the v2 B-tree header */
+    hdr = bt2->hdr;
+
     /* Check for empty B-tree */
     if(0 == hdr->root.all_nrec)
         HGOTO_ERROR(H5E_BTREE, H5E_NOTFOUND, FAIL, "record is not in B-tree")
@@ -783,7 +821,7 @@ H5B2_remove_by_idx(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type,
 
 done:
     /* Close the B-tree */
-    if(hdr && H5B2_close(hdr, dxpl_id) < 0)
+    if(bt2 && H5B2_close(bt2, dxpl_id) < 0)
         HDONE_ERROR(H5E_BTREE, H5E_CANTCLOSEOBJ, FAIL, "unable to close B-tree")
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -804,30 +842,37 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5B2_get_nrec(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
+H5B2_get_nrec(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *cls, haddr_t addr,
            hsize_t *nrec)
 {
-    H5B2_hdr_t	*hdr = NULL;            /* Pointer to the B-tree header */
+    H5B2_t	*bt2 = NULL;            /* Pointer to the B-tree */
+    H5B2_hdr_t	*hdr;                   /* Pointer to the B-tree header */
     herr_t	ret_value = SUCCEED;    /* Return value */
 
     FUNC_ENTER_NOAPI(H5B2_get_nrec, FAIL)
 
     /* Check arguments. */
     HDassert(f);
-    HDassert(type);
+    HDassert(cls);
     HDassert(H5F_addr_defined(addr));
     HDassert(nrec);
 
-    /* Open the B-tree header */
-    if(NULL == (hdr = H5B2_open(f, dxpl_id, type, addr, H5AC_READ)))
+    /* Open the B-tree */
+    if(NULL == (bt2 = H5B2_open(f, dxpl_id, cls, addr)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTOPENOBJ, FAIL, "unable to open B-tree")
 
+    /* Set the shared v2 B-tree header's file context for this operation */
+    bt2->hdr->f = bt2->f;
+
+    /* Get the v2 B-tree header */
+    hdr = bt2->hdr;
+
     /* Get B-tree number of records */
     *nrec = hdr->root.all_nrec;
 
 done:
     /* Close the B-tree */
-    if(hdr && H5B2_close(hdr, dxpl_id) < 0)
+    if(bt2 && H5B2_close(bt2, dxpl_id) < 0)
         HDONE_ERROR(H5E_BTREE, H5E_CANTCLOSEOBJ, FAIL, "unable to close B-tree")
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -860,24 +905,31 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5B2_neighbor(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
+H5B2_neighbor(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *cls, haddr_t addr,
     H5B2_compare_t range, void *udata, H5B2_found_t op, void *op_data)
 {
-    H5B2_hdr_t	*hdr = NULL;              /* Pointer to the B-tree header */
+    H5B2_t	*bt2 = NULL;            /* Pointer to the B-tree */
+    H5B2_hdr_t	*hdr;                   /* Pointer to the B-tree header */
     herr_t	ret_value = SUCCEED;    /* Return value */
 
     FUNC_ENTER_NOAPI(H5B2_neighbor, FAIL)
 
     /* Check arguments. */
     HDassert(f);
-    HDassert(type);
+    HDassert(cls);
     HDassert(H5F_addr_defined(addr));
     HDassert(op);
 
-    /* Open the B-tree header */
-    if(NULL == (hdr = H5B2_open(f, dxpl_id, type, addr, H5AC_READ)))
+    /* Open the B-tree */
+    if(NULL == (bt2 = H5B2_open(f, dxpl_id, cls, addr)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTOPENOBJ, FAIL, "unable to open B-tree")
 
+    /* Set the shared v2 B-tree header's file context for this operation */
+    bt2->hdr->f = bt2->f;
+
+    /* Get the v2 B-tree header */
+    hdr = bt2->hdr;
+
     /* Check for empty tree */
     if(!H5F_addr_defined(hdr->root.addr))
         HGOTO_ERROR(H5E_BTREE, H5E_NOTFOUND, FAIL, "B-tree has no records")
@@ -894,7 +946,7 @@ H5B2_neighbor(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
 
 done:
     /* Close the B-tree */
-    if(hdr && H5B2_close(hdr, dxpl_id) < 0)
+    if(bt2 && H5B2_close(bt2, dxpl_id) < 0)
         HDONE_ERROR(H5E_BTREE, H5E_CANTCLOSEOBJ, FAIL, "unable to close B-tree")
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -902,64 +954,6 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5B2_delete
- *
- * Purpose:	Delete an entire B-tree from a file.
- *
- *              The 'OP' routine is called for each record and the
- *              OP_DATA pointer, to allow caller to perform an operation as
- *              each record is removed from the B-tree.
- *
- *              If 'OP' is NULL, the records are just removed in the process
- *              of deleting the B-tree.
- *
- * Note:	The records are _not_ guaranteed to be visited in order.
- *
- * Return:	Non-negative on success, negative on failure.
- *
- * Programmer:	Quincey Koziol
- *		koziol@ncsa.uiuc.edu
- *		Mar  9 2005
- *
- *-------------------------------------------------------------------------
- */
-herr_t
-H5B2_delete(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
-    H5B2_remove_t op, void *op_data)
-{
-    H5B2_hdr_t	*hdr = NULL;            /* Pointer to the B-tree header */
-    herr_t	ret_value = SUCCEED;    /* Return value */
-
-    FUNC_ENTER_NOAPI(H5B2_delete, FAIL)
-
-    /* Check arguments. */
-    HDassert(f);
-    HDassert(type);
-    HDassert(H5F_addr_defined(addr));
-
-    /* Open the B-tree header */
-    if(NULL == (hdr = H5B2_open(f, dxpl_id, type, addr, H5AC_WRITE)))
-	HGOTO_ERROR(H5E_BTREE, H5E_CANTOPENOBJ, FAIL, "unable to open B-tree")
-
-    /* Delete all nodes in B-tree */
-    if(H5F_addr_defined(hdr->root.addr))
-        if(H5B2_delete_node(f, dxpl_id, hdr, hdr->depth, &hdr->root, op, op_data) < 0)
-            HGOTO_ERROR(H5E_BTREE, H5E_CANTDELETE, FAIL, "unable to delete B-tree nodes")
-
-    /* Mark B-tree header for deletion */
-    if(H5B2_hdr_delete(hdr) < 0)
-        HGOTO_ERROR(H5E_BTREE, H5E_CANTDELETE, FAIL, "unable to mark B-tree header for deletion")
-
-done:
-    /* Close the B-tree */
-    if(hdr && H5B2_close(hdr, dxpl_id) < 0)
-        HDONE_ERROR(H5E_BTREE, H5E_CANTCLOSEOBJ, FAIL, "unable to close B-tree")
-
-    FUNC_LEAVE_NOAPI(ret_value)
-} /* H5B2_delete() */
-
-
-/*-------------------------------------------------------------------------
  * Function:	H5B2_modify
  *
  * Purpose:	Locate the specified information in a B-tree and modify it.
@@ -980,10 +974,11 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5B2_modify(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
+H5B2_modify(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *cls, haddr_t addr,
     void *udata, H5B2_modify_t op, void *op_data)
 {
-    H5B2_hdr_t	*hdr = NULL;            /* Pointer to the B-tree header */
+    H5B2_t	*bt2 = NULL;            /* Pointer to the B-tree */
+    H5B2_hdr_t	*hdr;                   /* Pointer to the B-tree header */
     H5B2_node_ptr_t curr_node_ptr;      /* Node pointer info for current node */
     unsigned    depth;                  /* Current depth of the tree */
     int         cmp;                    /* Comparison value of records */
@@ -994,14 +989,20 @@ H5B2_modify(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
 
     /* Check arguments. */
     HDassert(f);
-    HDassert(type);
+    HDassert(cls);
     HDassert(H5F_addr_defined(addr));
     HDassert(op);
 
-    /* Open the B-tree header */
-    if(NULL == (hdr = H5B2_open(f, dxpl_id, type, addr, H5AC_READ)))
+    /* Open the B-tree */
+    if(NULL == (bt2 = H5B2_open(f, dxpl_id, cls, addr)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTOPENOBJ, FAIL, "unable to open B-tree")
 
+    /* Set the shared v2 B-tree header's file context for this operation */
+    bt2->hdr->f = bt2->f;
+
+    /* Get the v2 B-tree header */
+    hdr = bt2->hdr;
+
     /* Make copy of the root node pointer to start search with */
     curr_node_ptr = hdr->root;
 
@@ -1119,7 +1120,7 @@ H5B2_modify(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr,
 
 done:
     /* Close the B-tree */
-    if(hdr && H5B2_close(hdr, dxpl_id) < 0)
+    if(bt2 && H5B2_close(bt2, dxpl_id) < 0)
         HDONE_ERROR(H5E_BTREE, H5E_CANTCLOSEOBJ, FAIL, "unable to close B-tree")
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -1140,23 +1141,30 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5B2_iterate_size(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t addr, hsize_t *btree_size)
+H5B2_iterate_size(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *cls, haddr_t addr, hsize_t *btree_size)
 {
-    H5B2_hdr_t      	*hdr = NULL;        /* Pointer to the B-tree header */
-    herr_t      	ret_value = SUCCEED;/* Return value */
+    H5B2_t	*bt2 = NULL;            /* Pointer to the B-tree */
+    H5B2_hdr_t	*hdr;                   /* Pointer to the B-tree header */
+    herr_t      ret_value = SUCCEED;    /* Return value */
 
     FUNC_ENTER_NOAPI(H5B2_iterate_size, FAIL)
 
     /* Check arguments. */
     HDassert(f);
-    HDassert(type);
+    HDassert(cls);
     HDassert(H5F_addr_defined(addr));
     HDassert(btree_size);
 
-    /* Open the B-tree header */
-    if(NULL == (hdr = H5B2_open(f, dxpl_id, type, addr, H5AC_READ)))
+    /* Open the B-tree */
+    if(NULL == (bt2 = H5B2_open(f, dxpl_id, cls, addr)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTOPENOBJ, FAIL, "unable to open B-tree")
 
+    /* Set the shared v2 B-tree header's file context for this operation */
+    bt2->hdr->f = bt2->f;
+
+    /* Get the v2 B-tree header */
+    hdr = bt2->hdr;
+
     /* Add size of header to B-tree metadata total */
     *btree_size += H5B2_HEADER_SIZE(f);
 
@@ -1173,7 +1181,7 @@ H5B2_iterate_size(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *type, haddr_t add
 
 done:
     /* Close the B-tree */
-    if(hdr && H5B2_close(hdr, dxpl_id) < 0)
+    if(bt2 && H5B2_close(bt2, dxpl_id) < 0)
         HDONE_ERROR(H5E_BTREE, H5E_CANTCLOSEOBJ, FAIL, "unable to close B-tree")
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -1194,27 +1202,136 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5B2_close(H5B2_hdr_t *hdr, hid_t dxpl_id)
+H5B2_close(H5B2_t *bt2, hid_t dxpl_id)
 {
-    unsigned    hdr_flags = H5AC__NO_FLAGS_SET;   /* Metadata cache flags for unprotecting header */
-    herr_t	ret_value = SUCCEED;    /* Return value */
+    const H5B2_class_t *cls = NULL;     /* Class of v2 B-tree client */
+    haddr_t bt2_addr = HADDR_UNDEF;     /* Address of v2 B-tree (for deletion) */
+    hbool_t pending_delete = FALSE;     /* Whether the v2 B-tree is pending deletion */
+    herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT(H5B2_close)
 
     /* Check arguments. */
-    HDassert(hdr);
-    HDassert(hdr->f);
-    HDassert(H5F_addr_defined(hdr->addr));
+    HDassert(bt2);
+    HDassert(bt2->f);
+
+    /* Decrement file reference & check if this is the last open v2 B-tree using the shared B-tree header */
+    if(0 == H5B2_hdr_fuse_decr(bt2->hdr)) {
+        /* Set the shared v2 B-tree header's file context for this operation */
+        bt2->hdr->f = bt2->f;
+
+        /* Check for pending B-tree deletion */
+        if(bt2->hdr->pending_delete) {
+            /* Set local info, so B-tree deletion can occur after decrementing the
+             *  header's ref count
+             */
+            pending_delete = TRUE;
+            bt2_addr = bt2->hdr->addr;
+            cls = bt2->hdr->cls;
+        } /* end if */
+    } /* end if */
 
-    /* Check if we are supposed to delete the header */
-    if(hdr->pending_delete)
-        hdr_flags = H5AC__DIRTIED_FLAG | H5AC__DELETED_FLAG | H5AC__FREE_FILE_SPACE_FLAG;
+    /* Decrement the reference count on the B-tree header */
+    /* (don't put in H5B2_hdr_fuse_decr() as the B-tree header may be evicted
+     *  immediately -QAK)
+     */
+    if(H5B2_hdr_decr(bt2->hdr) < 0)
+        HGOTO_ERROR(H5E_BTREE, H5E_CANTDEC, FAIL, "can't decrement reference count on shared v2 B-tree header")
+
+    /* Check for pending v2 B-tree deletion */
+    if(pending_delete) {
+        H5B2_hdr_t *hdr;            /* Another pointer to v2 B-tree header */
+
+        /* Sanity check */
+        HDassert(H5F_addr_defined(bt2_addr));
+        HDassert(cls);
 
-    /* Release the B-tree header info */
-    if(H5AC_unprotect(hdr->f, dxpl_id, H5AC_BT2_HDR, hdr->addr, hdr, hdr_flags) < 0)
-        HGOTO_ERROR(H5E_BTREE, H5E_CANTUNPROTECT, FAIL, "unable to release B-tree header")
+        /* Lock the v2 B-tree header into memory */
+        if(NULL == (hdr = (H5B2_hdr_t *)H5AC_protect(bt2->f, dxpl_id, H5AC_BT2_HDR, bt2_addr, cls, NULL, H5AC_WRITE)))
+            HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load v2 B-tree header")
+
+        /* Set the shared v2 B-tree header's file context for this operation */
+        hdr->f = bt2->f;
+
+        /* Delete v2 B-tree, starting with header (unprotects header) */
+        if(H5B2_hdr_delete(hdr, dxpl_id) < 0)
+            HGOTO_ERROR(H5E_BTREE, H5E_CANTDELETE, FAIL, "unable to delete v2 B-tree")
+    } /* end if */
+
+    /* Release the v2 B-tree wrapper */
+    bt2 = H5FL_FREE(H5B2_t, bt2);
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* H5B2_close() */
 
+
+/*-------------------------------------------------------------------------
+ * Function:	H5B2_delete
+ *
+ * Purpose:	Delete an entire B-tree from a file.
+ *
+ *              The 'OP' routine is called for each record and the
+ *              OP_DATA pointer, to allow caller to perform an operation as
+ *              each record is removed from the B-tree.
+ *
+ *              If 'OP' is NULL, the records are just removed in the process
+ *              of deleting the B-tree.
+ *
+ * Note:	The records are _not_ guaranteed to be visited in order.
+ *
+ * Return:	Non-negative on success, negative on failure.
+ *
+ * Programmer:	Quincey Koziol
+ *		koziol@ncsa.uiuc.edu
+ *		Mar  9 2005
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5B2_delete(H5F_t *f, hid_t dxpl_id, const H5B2_class_t *cls, haddr_t addr,
+    H5B2_remove_t op, void *op_data)
+{
+    H5B2_hdr_t	*hdr = NULL;            /* Pointer to the B-tree header */
+    herr_t	ret_value = SUCCEED;    /* Return value */
+
+    FUNC_ENTER_NOAPI(H5B2_delete, FAIL)
+
+    /* Check arguments. */
+    HDassert(f);
+    HDassert(cls);
+    HDassert(H5F_addr_defined(addr));
+
+    /* Lock the v2 B-tree header into memory */
+#ifdef QAK
+HDfprintf(stderr, "%s: addr = %a\n", FUNC, addr);
+#endif /* QAK */
+    if(NULL == (hdr = (H5B2_hdr_t *)H5AC_protect(f, dxpl_id, H5AC_BT2_HDR, addr, cls, NULL, H5AC_WRITE)))
+        HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load v2 B-tree header")
+
+    /* Remember the callback & context for later */
+    hdr->remove_op = op;
+    hdr->remove_op_data = op_data;
+
+    /* Check for files using shared v2 B-tree header */
+    if(hdr->file_rc)
+        hdr->pending_delete = TRUE;
+    else {
+        /* Set the shared v2 B-tree header's file context for this operation */
+        hdr->f = f;
+
+        /* Delete v2 B-tree now, starting with header (unprotects header) */
+        if(H5B2_hdr_delete(hdr, dxpl_id) < 0)
+            HGOTO_ERROR(H5E_BTREE, H5E_CANTDELETE, FAIL, "unable to delete v2 B-tree")
+        hdr = NULL;
+    } /* end if */
+
+done:
+    /* Unprotect the header, if an error occurred */
+    if(hdr && H5AC_unprotect(f, dxpl_id, H5AC_BT2_HDR, addr, hdr, H5AC__NO_FLAGS_SET) < 0)
+        HDONE_ERROR(H5E_BTREE, H5E_CANTUNPROTECT, FAIL, "unable to release v2 B-tree header")
+
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5B2_delete() */
+