Switch to new, more scalable, metadata cache entry tagging.

13 files changed, 381 insertions, 325 deletions

diff --git a/src/H5AC.c b/src/H5AC.c
index 8433e77..3b19db4 100644
--- a/src/H5AC.c
+++ b/src/H5AC.c
@@ -2269,7 +2269,6 @@ done:
 herr_t
 H5AC_tag(hid_t dxpl_id, haddr_t metadata_tag, haddr_t *prev_tag)
 {
-    H5C_tag_t tag;                  /* Tag structure */
     H5P_genplist_t *dxpl;           /* Dataset transfer property list */
     herr_t ret_value = SUCCEED;     /* Return value */
 
@@ -2281,32 +2280,16 @@ H5AC_tag(hid_t dxpl_id, haddr_t metadata_tag, haddr_t *prev_tag)
 
     /* Get the current tag value and return that (if prev_tag is NOT null) */
     if(prev_tag) {
-        if((H5P_get(dxpl, "H5C_tag", &tag)) < 0)
+        haddr_t tag;                    /* Tag value */
+
+        if((H5P_get(dxpl, H5AC_TAG_NAME, &tag)) < 0)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to query dxpl")
-        *prev_tag = tag.value;
+        *prev_tag = tag;
     } /* end if */
 
-    /* Add metadata_tag to tag structure */
-    tag.value = metadata_tag;
-
-    /* Determine globality of tag */
-    switch(metadata_tag) {
-        case H5AC__SUPERBLOCK_TAG:
-        case H5AC__SOHM_TAG:
-        case H5AC__GLOBALHEAP_TAG:
-            tag.globality = H5C_GLOBALITY_MAJOR;
-            break;
-        case H5AC__FREESPACE_TAG:
-            tag.globality = H5C_GLOBALITY_MINOR;
-            break;
-        default:
-            tag.globality = H5C_GLOBALITY_NONE;
-            break;
-    } /* end switch */
-
     /* Set the provided tag in the dxpl_id. */
-    if(H5P_set(dxpl, "H5C_tag", &tag) < 0)
-        HGOTO_ERROR(H5E_CACHE, H5E_CANTSET, FAIL, "can't set property in dxpl")
+    if(H5P_set(dxpl, H5AC_TAG_NAME, &metadata_tag) < 0)
+        HGOTO_ERROR(H5E_CACHE, H5E_CANTSET, FAIL, "can't set tag in dxpl")
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -2506,7 +2489,7 @@ static herr_t
 H5AC__verify_tag(hid_t dxpl_id, const H5AC_class_t *type)
 {
     H5P_genplist_t *dxpl;               /* DXPL for operation */
-    H5C_tag_t tag;                      /* Entry tag to validate */
+    haddr_t tag;                        /* Entry tag to validate */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_STATIC
@@ -2516,11 +2499,11 @@ H5AC__verify_tag(hid_t dxpl_id, const H5AC_class_t *type)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list")
 
     /* Get the tag from the DXPL */
-    if((H5P_get(dxpl, "H5C_tag", &tag)) < 0)
+    if((H5P_get(dxpl, H5AC_TAG_NAME, &tag)) < 0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to query property value")
 
     /* Verify legal tag value */
-    if(H5C_verify_tag(type->id, tag.value, tag.globality) < 0)
+    if(H5C_verify_tag(type->id, tag) < 0)
         HGOTO_ERROR(H5E_CACHE, H5E_CANTGET, FAIL, "tag verification failed")
 
 done:
diff --git a/src/H5ACpkg.h b/src/H5ACpkg.h
index a689ffd..a298f85 100644
--- a/src/H5ACpkg.h
+++ b/src/H5ACpkg.h
@@ -42,7 +42,6 @@
 /* Get needed headers */
 #include "H5Cprivate.h"         /* Cache                                */
 #include "H5FLprivate.h"        /* Free Lists                           */
-#include "H5SLprivate.h"        /* Skip lists */
 
 /*****************************/
 /* Package Private Variables */
diff --git a/src/H5ACprivate.h b/src/H5ACprivate.h
index 739cbce..abd1af0 100644
--- a/src/H5ACprivate.h
+++ b/src/H5ACprivate.h
@@ -35,6 +35,7 @@
 #include "H5Cprivate.h"		/* Cache				*/
 #include "H5Fprivate.h"		/* File access				*/
 #include "H5Pprivate.h"		/* Property lists			*/
+#include "H5SLprivate.h"        /* Skip lists 				*/
 
 #ifdef H5_METADATA_TRACE_FILE
 #define H5AC__TRACE_FILE_ENABLED	1
@@ -45,11 +46,16 @@
 /* Global metadata tag values */
 #define H5AC__INVALID_TAG      (haddr_t)0
 #define H5AC__IGNORE_TAG       (haddr_t)1
-#define H5AC__SUPERBLOCK_TAG   (haddr_t)2
-#define H5AC__FREESPACE_TAG    (haddr_t)3
-#define H5AC__SOHM_TAG         (haddr_t)4
-#define H5AC__GLOBALHEAP_TAG   (haddr_t)5
-#define H5AC__COPIED_TAG       (haddr_t)6
+#define H5AC__COPIED_TAG       (haddr_t)2
+#define H5AC__SUPERBLOCK_TAG   (haddr_t)3
+#define H5AC__FREESPACE_TAG    (haddr_t)4
+#define H5AC__SOHM_TAG         (haddr_t)5
+#define H5AC__GLOBALHEAP_TAG   (haddr_t)6
+
+/* Definitions for cache "tag" property */
+#define H5AC_TAG_NAME          "H5AC_tag"
+#define H5AC_TAG_SIZE          sizeof(haddr_t)
+#define H5AC_TAG_DEF           (H5AC__INVALID_TAG)
 
 /* Types of metadata objects cached */
 typedef enum {
diff --git a/src/H5C.c b/src/H5C.c
index 8b11755..6b3ad73 100644
--- a/src/H5C.c
+++ b/src/H5C.c
@@ -197,6 +197,9 @@ static void H5C__assert_flush_dep_nocycle(const H5C_cache_entry_t * entry,
 /* Package initialization variable */
 hbool_t H5_PKG_INIT_VAR = FALSE;
 
+/* Declare a free list to manage the tag info struct */
+H5FL_DEFINE(H5C_tag_info_t);
+
 
 /*****************************/
 /* Library Private Variables */
@@ -216,9 +219,6 @@ H5FL_BLK_DEFINE_STATIC(parent);
 /* Declare extern free list to manage the H5C_collective_write_t struct */
 H5FL_EXTERN(H5C_collective_write_t);
 
-/* Declare a free list to manage corked object addresses */
-H5FL_DEFINE_STATIC(haddr_t);
-
 
 
 /*-------------------------------------------------------------------------
@@ -280,8 +280,8 @@ H5C_create(size_t		      max_cache_size,
     if(NULL == (cache_ptr->slist_ptr = H5SL_create(H5SL_TYPE_HADDR, NULL)))
         HGOTO_ERROR(H5E_CACHE, H5E_CANTCREATE, NULL, "can't create skip list.")
 
-    if ( (cache_ptr->cork_list_ptr = H5SL_create(H5SL_TYPE_HADDR, NULL)) == NULL )
-        HGOTO_ERROR(H5E_CACHE, H5E_CANTCREATE, NULL, "can't create skip list for corked object addresses.")
+    if(NULL == (cache_ptr->tag_list = H5SL_create(H5SL_TYPE_HADDR, NULL)))
+        HGOTO_ERROR(H5E_CACHE, H5E_CANTCREATE, NULL, "can't create skip list for tagged entry addresses.")
 
     /* If we get this far, we should succeed.  Go ahead and initialize all
      * the fields.
@@ -457,8 +457,8 @@ done:
             if(cache_ptr->slist_ptr != NULL)
                 H5SL_close(cache_ptr->slist_ptr);
 
-            if ( cache_ptr->cork_list_ptr != NULL )
-                H5SL_close(cache_ptr->cork_list_ptr);
+            if(cache_ptr->tag_list != NULL)
+                H5SL_close(cache_ptr->tag_list);
 
             cache_ptr->magic = 0;
             cache_ptr = H5FL_FREE(H5C_t, cache_ptr);
@@ -656,10 +656,9 @@ H5C_def_auto_resize_rpt_fcn(H5C_t * cache_ptr,
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5C_free_cork_list_cb
+ * Function:    H5C_free_tag_list_cb
  *
- * Purpose:     Callback function to free the list of object addresses 
- *		on the skip list.
+ * Purpose:     Callback function to free tag nodes from the skip list.
  *
  * Return:      Non-negative on success/Negative on failure
  *
@@ -669,19 +668,19 @@ H5C_def_auto_resize_rpt_fcn(H5C_t * cache_ptr,
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5C_free_cork_list_cb(void *_item, void H5_ATTR_UNUSED *key, void H5_ATTR_UNUSED *op_data)
+H5C_free_tag_list_cb(void *_item, void H5_ATTR_UNUSED *key, void H5_ATTR_UNUSED *op_data)
 {
-    haddr_t *addr = (haddr_t *)_item;
+    H5C_tag_info_t *tag_info = (H5C_tag_info_t *)_item;
 
     FUNC_ENTER_NOAPI_NOINIT_NOERR
 
-    HDassert(addr);
+    HDassert(tag_info);
 
     /* Release the item */
-    addr = H5FL_FREE(haddr_t, addr);
+    tag_info = H5FL_FREE(H5C_tag_info_t, tag_info);
 
     FUNC_LEAVE_NOAPI(0)
-}  /* H5C_free_cork_list_cb() */
+}  /* H5C_free_tag_list_cb() */
 
 
 /*-------------------------------------------------------------------------
@@ -729,9 +728,9 @@ H5C_dest(H5F_t * f, hid_t dxpl_id)
         cache_ptr->slist_ptr = NULL;
     } /* end if */
 
-    if(cache_ptr->cork_list_ptr != NULL) {
-        H5SL_destroy(cache_ptr->cork_list_ptr, H5C_free_cork_list_cb, NULL);
-        cache_ptr->cork_list_ptr = NULL;
+    if(cache_ptr->tag_list != NULL) {
+        H5SL_destroy(cache_ptr->tag_list, H5C_free_tag_list_cb, NULL);
+        cache_ptr->tag_list = NULL;
     } /* end if */
 
 #ifndef NDEBUG
@@ -1284,14 +1283,6 @@ H5C_insert_entry(H5F_t *             f,
     entry_ptr->image_ptr = NULL;
     entry_ptr->image_up_to_date = FALSE;
 
-    /* Apply tag to newly inserted entry */
-    if(H5C__tag_entry(cache_ptr, entry_ptr, dxpl_id) < 0)
-        HGOTO_ERROR(H5E_CACHE, H5E_CANTTAG, FAIL, "Cannot tag metadata entry")
-
-    /* Set the entry's cork status */
-    if(H5C_cork(cache_ptr, entry_ptr->tag, H5C__GET_CORKED, &entry_ptr->is_corked) < 0)
-        HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "Cannot retrieve entry's cork status")
-
     entry_ptr->is_protected = FALSE;
     entry_ptr->is_read_only = FALSE;
     entry_ptr->ro_ref_count = 0;
@@ -1359,6 +1350,10 @@ H5C_insert_entry(H5F_t *             f,
     entry_ptr->coll_prev = NULL;
 #endif /* H5_HAVE_PARALLEL */
 
+    /* Apply tag to newly inserted entry */
+    if(H5C__tag_entry(cache_ptr, entry_ptr, dxpl_id) < 0)
+        HGOTO_ERROR(H5E_CACHE, H5E_CANTTAG, FAIL, "Cannot tag metadata entry")
+
     H5C__RESET_CACHE_ENTRY_STATS(entry_ptr)
 
     if(cache_ptr->flash_size_increase_possible &&
@@ -1858,8 +1853,9 @@ H5C_resize_entry(void *thing, size_t new_size)
         if(!entry_ptr->in_slist)
             H5C__INSERT_ENTRY_IN_SLIST(cache_ptr, entry_ptr, FAIL)
 
-        if(entry_ptr->is_pinned)
+        if(entry_ptr->is_pinned) {
             H5C__UPDATE_STATS_FOR_DIRTY_PIN(cache_ptr, entry_ptr)
+        } /* end if */
     } /* end if */
 
 done:
@@ -2190,22 +2186,21 @@ H5C_protect(H5F_t *		f,
 
 #if H5C_DO_TAGGING_SANITY_CHECKS
 {
-        H5C_tag_t tag;              /* Tag structure */
+        /* Verify tag value */
+        if(cache_ptr->ignore_tags != TRUE) {
+            haddr_t tag;              /* Tag value */
 
-        /* The entry is already in the cache, but make sure that the tag value 
-           being passed in via dxpl is still legal. This will ensure that had
-           the entry NOT been in the cache, tagging was still set up correctly
-           and it would have received a legal tag value after getting loaded
-           from disk. */
+            /* The entry is already in the cache, but make sure that the tag value 
+               being passed in via dxpl is still legal. This will ensure that had
+               the entry NOT been in the cache, tagging was still set up correctly
+               and it would have received a legal tag value after getting loaded
+               from disk. */
 
-        /* Get the tag from the DXPL */
-        if((H5P_get(dxpl, "H5C_tag", &tag)) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "unable to query property value");
+            /* Get the tag from the DXPL */
+            if((H5P_get(dxpl, H5AC_TAG_NAME, &tag)) < 0)
+                HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "unable to query property value");
     
-        /* Verify tag value */
-        if(cache_ptr->ignore_tags != TRUE) {
-            /* Verify legal tag value */
-            if(H5C_verify_tag(entry_ptr->type->id, tag.value, tag.globality) < 0)
+            if(H5C_verify_tag(entry_ptr->type->id, tag) < 0)
                 HGOTO_ERROR(H5E_CACHE, H5E_CANTGET, NULL, "tag verification failed")
         } /* end if */
 }
@@ -2238,10 +2233,6 @@ H5C_protect(H5F_t *		f,
         if(H5C__tag_entry(cache_ptr, entry_ptr, dxpl_id) < 0)
             HGOTO_ERROR(H5E_CACHE, H5E_CANTTAG, NULL, "Cannot tag metadata entry")
 
-	/* Set the entry's cork status */
-	if(H5C_cork(cache_ptr, entry_ptr->tag, H5C__GET_CORKED, &entry_ptr->is_corked) < 0)
-	    HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, NULL, "Cannot retrieve entry's cork status")
-
         /* If the entry is very large, and we are configured to allow it,
          * we may wish to perform a flash cache size increase.
          */
@@ -4342,31 +4333,30 @@ H5C__autoadjust__ageout__evict_aged_out_entries(H5F_t * f,
 	    if(prev_ptr != NULL)
                 prev_is_dirty = prev_ptr->is_dirty;
 
-	    /* dirty corked entry is skipped */
-	    if(entry_ptr->is_corked && entry_ptr->is_dirty)
-		corked = TRUE;
-            else if ( entry_ptr->is_dirty ) {
-
-                /* reset entries_removed_counter and
-                 * last_entry_removed_ptr prior to the call to
-                 * H5C__flush_single_entry() so that we can spot
-                 * unexpected removals of entries from the cache,
-                 * and set the restart_scan flag if proceeding
-                 * would be likely to cause us to scan an entry
-                 * that is no longer in the cache.
-                 */
-                cache_ptr->entries_removed_counter = 0;
-                cache_ptr->last_entry_removed_ptr  = NULL;
-
-                if(H5C__flush_single_entry(f, dxpl_id, entry_ptr, H5C__NO_FLAGS_SET, NULL, NULL) < 0)
-                    HGOTO_ERROR(H5E_CACHE, H5E_CANTFLUSH, FAIL, "unable to flush entry")
-
-                if ( ( cache_ptr->entries_removed_counter > 1 ) ||
-                     ( cache_ptr->last_entry_removed_ptr == prev_ptr ) )
+            if(entry_ptr->is_dirty ) {
+                /* dirty corked entry is skipped */
+                if(entry_ptr->tag_info && entry_ptr->tag_info->corked)
+                    corked = TRUE;
+                else {
+                    /* reset entries_removed_counter and
+                     * last_entry_removed_ptr prior to the call to
+                     * H5C__flush_single_entry() so that we can spot
+                     * unexpected removals of entries from the cache,
+                     * and set the restart_scan flag if proceeding
+                     * would be likely to cause us to scan an entry
+                     * that is no longer in the cache.
+                     */
+                    cache_ptr->entries_removed_counter = 0;
+                    cache_ptr->last_entry_removed_ptr  = NULL;
 
-                    restart_scan = TRUE;
+                    if(H5C__flush_single_entry(f, dxpl_id, entry_ptr, H5C__NO_FLAGS_SET, NULL, NULL) < 0)
+                        HGOTO_ERROR(H5E_CACHE, H5E_CANTFLUSH, FAIL, "unable to flush entry")
 
-            } else {
+                    if(cache_ptr->entries_removed_counter > 1 || cache_ptr->last_entry_removed_ptr == prev_ptr)
+                        restart_scan = TRUE;
+                } /* end else */
+            } /* end if */
+            else {
 
                 bytes_evicted += entry_ptr->size;
 
@@ -6143,6 +6133,8 @@ H5C__flush_single_entry(const H5F_t *f, hid_t dxpl_id, H5C_cache_entry_t *entry_
          *
          * 3) Update the replacement policy for eviction
          *
+         * 4) Remove it from the tag list for this object
+         *
          * Finally, if the destroy_entry flag is set, discard the 
          * entry.
          */
@@ -6154,6 +6146,10 @@ H5C__flush_single_entry(const H5F_t *f, hid_t dxpl_id, H5C_cache_entry_t *entry_
 
         H5C__UPDATE_RP_FOR_EVICTION(cache_ptr, entry_ptr, FAIL)
 
+        /* Remove entry from tag list */
+        if(H5C__untag_entry(cache_ptr, entry_ptr) < 0)
+            HGOTO_ERROR(H5E_CACHE, H5E_CANTREMOVE, FAIL, "can't remove entry from tag list")
+
 	/* verify that the entry is no longer part of any flush dependencies */
         HDassert(entry_ptr->flush_dep_nparents == 0);
 	HDassert(entry_ptr->flush_dep_nchildren == 0);
@@ -6890,7 +6886,8 @@ H5C_make_space_in_cache(H5F_t *	f,
 	    if(prev_ptr != NULL)
 		prev_is_dirty = prev_ptr->is_dirty;
 
-	    if (entry_ptr->is_corked && entry_ptr->is_dirty) {
+	    if(entry_ptr->is_dirty &&
+                    (entry_ptr->tag_info && entry_ptr->tag_info->corked)) {
 
                 /* Skip "dirty" corked entries.  */
 		++num_corked_entries;
@@ -7615,8 +7612,8 @@ done:
 herr_t
 H5C_cork(H5C_t *cache_ptr, haddr_t obj_addr, unsigned action, hbool_t *corked) 
 {
-    haddr_t *ptr;		/* Points to an address */
-    herr_t ret_value = SUCCEED;	/* Return value */
+    H5C_tag_info_t *tag_info;	/* Points to a tag info struct */
+    herr_t              ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI_NOINIT
 
@@ -7626,61 +7623,69 @@ H5C_cork(H5C_t *cache_ptr, haddr_t obj_addr, unsigned action, hbool_t *corked)
     HDassert(action == H5C__SET_CORK || action == H5C__UNCORK || action == H5C__GET_CORKED);
 
     /* Search the list of corked object addresses in the cache */
-    ptr = (haddr_t *)H5SL_search(cache_ptr->cork_list_ptr, &obj_addr);
+    tag_info = (H5C_tag_info_t *)H5SL_search(cache_ptr->tag_list, &obj_addr);
 
     if(H5C__GET_CORKED == action) {
         HDassert(corked);
-        if(ptr != NULL && *ptr == obj_addr)
+        if(tag_info != NULL && tag_info->corked)
             *corked = TRUE;
         else
             *corked = FALSE;
     } /* end if */
     else {
-        hbool_t is_corked;		/* Cork status for an entry */
-
         /* Sanity check */
         HDassert(H5C__SET_CORK == action || H5C__UNCORK == action);
 
         /* Perform appropriate action */
         if(H5C__SET_CORK == action) {
-            haddr_t *addr_ptr = NULL;	/* Points to an address */
-
-            if(ptr != NULL && *ptr == obj_addr)
-                HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "Can't cork an already corked object")
-
-            /* Allocate address */
-            if(NULL == (addr_ptr = H5FL_MALLOC(haddr_t)))
-                HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
-
-            /* Insert into the list */
-            *addr_ptr = obj_addr;
-            if(H5SL_insert(cache_ptr->cork_list_ptr, addr_ptr, addr_ptr) < 0) {
-                addr_ptr = H5FL_FREE(haddr_t, addr_ptr);
-                HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "Can't insert address into cork list")
+            /* Check if this is the first entry for this tagged object */
+            if(NULL == tag_info) {
+                /* Allocate new tag info struct */
+                if(NULL == (tag_info = H5FL_CALLOC(H5C_tag_info_t)))
+                    HGOTO_ERROR(H5E_CACHE, H5E_CANTALLOC, FAIL, "can't allocate tag info for cache entry")
+
+                /* Set the tag for all entries */
+                tag_info->tag = obj_addr;
+
+                /* Insert tag info into skip list */
+                if(H5SL_insert(cache_ptr->tag_list, tag_info, &(tag_info->tag)) < 0 )
+                    HGOTO_ERROR(H5E_CACHE, H5E_CANTINSERT, FAIL, "can't insert tag info in skip list")
             } /* end if */
+            else {
+                /* Check for object already corked */
+                if(tag_info->corked)
+                    HGOTO_ERROR(H5E_CACHE, H5E_CANTCORK, FAIL, "object already corked")
+                HDassert(tag_info->entry_cnt > 0 && tag_info->head);
+            } /* end else */
 
-            /* Set the entry's cork status */
-            is_corked = TRUE;
+            /* Set the corked status for the entire object */
+            tag_info->corked = TRUE;
         } /* end if */
         else {
-            if(ptr == NULL)
-                HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "Can't uncork an object that is not corked ")
+            /* Sanity check */
+            HDassert(tag_info);
 
-            /* Remove the object address from the list */
-            ptr = (haddr_t *)H5SL_remove(cache_ptr->cork_list_ptr, &obj_addr);
-            if(ptr == NULL || *ptr != obj_addr)
-                HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "Can't remove address from list")
+            /* Check for already uncorked */
+            if(!tag_info->corked)
+                HGOTO_ERROR(H5E_CACHE, H5E_CANTUNCORK, FAIL, "object already uncorked")
 
-            /* Free address */
-            ptr = H5FL_FREE(haddr_t, ptr);
+            /* Set the corked status for the entire object */
+            tag_info->corked = FALSE;
 
-            /* Set the entry's cork status */
-            is_corked = FALSE;
-        } /* end else */
+            /* Remove the tag info from the tag list, if there's no more entries with this tag */
+            if(0 == tag_info->entry_cnt) {
+                /* Sanity check */
+                HDassert(NULL == tag_info->head);
+
+                if(H5SL_remove(cache_ptr->tag_list, &(tag_info->tag)) != tag_info)
+                    HGOTO_ERROR(H5E_CACHE, H5E_CANTREMOVE, FAIL, "can't remove tag info from list")
 
-        /* Mark existing cache entries with tag (obj_addr) to the cork status */
-        if(H5C__mark_tagged_entries_cork(cache_ptr, obj_addr, is_corked) < 0)
-            HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "can't mark cork status on entry")
+                /* Release the tag info */
+                tag_info = H5FL_FREE(H5C_tag_info_t, tag_info);
+            } /* end if */
+            else
+                HDassert(NULL != tag_info->head);
+        } /* end else */
     } /* end else */
 
 done:
diff --git a/src/H5Cdbg.c b/src/H5Cdbg.c
index 08a7068..3961aa4 100644
--- a/src/H5Cdbg.c
+++ b/src/H5Cdbg.c
@@ -923,7 +923,7 @@ H5C__dump_children_cb(H5C_cache_entry_t *entry_ptr, void *_ctx)
 {
     H5C__dump_child_ctx_t *ctx = (H5C__dump_child_ctx_t *)_ctx;
 
-    if(entry_ptr->tag != entry_ptr->addr) {
+    if(entry_ptr->tag_info->tag != entry_ptr->addr) {
         unsigned u;
 
         HDassert(entry_ptr->flush_dep_nparents);
@@ -941,12 +941,14 @@ H5C__dump_children(H5C_t *cache_ptr, const H5C_cache_entry_t *entry_ptr,
 {
     H5C__dump_child_ctx_t ctx;
 
+    HDassert(entry_ptr->tag_info);
+
     ctx.cache_ptr = cache_ptr;
     ctx.parent = entry_ptr;
     ctx.dump_parents = dump_parents;
     ctx.prefix = prefix;
     ctx.indent = indent;
-    H5C__iter_tagged_entries(cache_ptr, entry_ptr->tag, FALSE, H5C__dump_children_cb, &ctx);
+    H5C__iter_tagged_entries(cache_ptr, entry_ptr->tag_info->tag, FALSE, H5C__dump_children_cb, &ctx);
 }
 
 void
@@ -956,7 +958,7 @@ H5C__dump_entry(H5C_t *cache_ptr, const H5C_cache_entry_t *entry_ptr,
     HDassert(cache_ptr);
     HDassert(entry_ptr);
 
-    HDfprintf(stderr, "%*s%s: entry_ptr = (%a, '%s', %a, %t, %u, %u/%u)\n", indent, "", prefix, entry_ptr->addr, entry_ptr->type->name, entry_ptr->tag, entry_ptr->is_dirty, entry_ptr->flush_dep_nparents, entry_ptr->flush_dep_nchildren, entry_ptr->flush_dep_ndirty_children);
+    HDfprintf(stderr, "%*s%s: entry_ptr = (%a, '%s', %a, %t, %u, %u/%u)\n", indent, "", prefix, entry_ptr->addr, entry_ptr->type->name, entry_ptr->tag_info ? entry_ptr->tag_info->tag : HADDR_UNDEF, entry_ptr->is_dirty, entry_ptr->flush_dep_nparents, entry_ptr->flush_dep_nchildren, entry_ptr->flush_dep_ndirty_children);
     if(dump_parents && entry_ptr->flush_dep_nparents)
         H5C__dump_parents(cache_ptr, entry_ptr, "Parent", indent);
     if(entry_ptr->flush_dep_nchildren)
diff --git a/src/H5Cpkg.h b/src/H5Cpkg.h
index c8f5c00..2967361 100644
--- a/src/H5Cpkg.h
+++ b/src/H5Cpkg.h
@@ -3112,6 +3112,14 @@ if ( ( (entry_ptr) == NULL ) ||                                                \
 /* Package Private Typedefs */
 /****************************/
 
+/* Info about each set of tagged entries */
+typedef struct H5C_tag_info_t {
+    haddr_t tag;                /* Tag (address) of the entries (must be first, for skiplist) */
+    H5C_cache_entry_t *head;    /* Head of the list of entries for this tag */
+    size_t entry_cnt;           /* Number of entries on list */
+    hbool_t corked;             /* Whether this object is corked */
+} H5C_tag_info_t;
+
 /****************************************************************************
  *
  * structure H5C_t
@@ -4096,7 +4104,8 @@ struct H5C_t {
     int64_t			slist_size_increase;
 #endif /* H5C_DO_SANITY_CHECKS */
 
-    H5SL_t *                    cork_list_ptr; /* list of corked object addresses */
+    /* Fields for maintaining list of tagged entries */
+    H5SL_t *                    tag_list;
 
     /* Fields for tracking protected entries */
     int32_t                     pl_len;
@@ -4263,14 +4272,13 @@ H5_DLLVAR const H5C_class_t H5C__epoch_marker_class;
 H5_DLL herr_t H5C__flush_single_entry(const H5F_t *f, hid_t dxpl_id,
     H5C_cache_entry_t *entry_ptr, unsigned flags, int64_t *entry_size_change_ptr, H5SL_t *collective_write_list);
 H5_DLL herr_t H5C__flush_marked_entries(H5F_t * f, hid_t dxpl_id);
-H5_DLL int H5C__iter_tagged_entries(H5C_t *cache, haddr_t tag, hbool_t match_global,
+H5_DLL herr_t H5C__iter_tagged_entries(H5C_t *cache, haddr_t tag, hbool_t match_global,
     H5C_tag_iter_cb_t cb, void *cb_ctx);
 
 /* Routines for operating on entry tags */
 H5_DLL herr_t H5C__tag_entry(H5C_t * cache_ptr, H5C_cache_entry_t * entry_ptr,
     hid_t dxpl_id);
-H5_DLL herr_t H5C__mark_tagged_entries_cork(H5C_t *cache_ptr, haddr_t obj_addr,
-    hbool_t val);
+H5_DLL herr_t H5C__untag_entry(H5C_t *cache, H5C_cache_entry_t *entry);
 
 /* Testing functions */
 #ifdef H5C_TESTING
diff --git a/src/H5Cprivate.h b/src/H5Cprivate.h
index 9b0dbd4..294d3a0b 100644
--- a/src/H5Cprivate.h
+++ b/src/H5Cprivate.h
@@ -204,11 +204,6 @@
 #define H5C__EVICT_ALLOW_LAST_PINS_FLAG         0x4000
 #define H5C__DEL_FROM_SLIST_ON_DESTROY_FLAG     0x8000
 
-/* Definitions for cache "tag" property */
-#define H5C_TAG_NAME           "H5C_tag"
-#define H5C_TAG_SIZE           sizeof(H5C_tag_t)
-#define H5C_TAG_DEF            {(haddr_t)0, H5C_GLOBALITY_NONE}
-
 /* Debugging/sanity checking/statistics settings */
 #ifndef NDEBUG
 #define H5C_DO_SANITY_CHECKS		1
@@ -271,19 +266,6 @@
 /* Typedef for the main structure for the cache (defined in H5Cpkg.h) */
 typedef struct H5C_t H5C_t;
 
-/* Define enum for cache entry tag 'globality' value */
-typedef enum {
-    H5C_GLOBALITY_NONE=0, /* Non-global tag */
-    H5C_GLOBALITY_MINOR,  /* global, not flushed during single object flush */
-    H5C_GLOBALITY_MAJOR   /* global, needs flushed during single obect flush */
-} H5C_tag_globality_t;
-
-/* Cache entry tag structure */
-typedef struct H5C_tag_t {
-    haddr_t value;
-    H5C_tag_globality_t globality;
-} H5C_tag_t;
-
 /*
  *
  * Struct H5C_class_t
@@ -1288,9 +1270,6 @@ typedef int H5C_ring_t;
  *		The name is not particularly descriptive, but is retained
  *		to avoid changes in existing code.
  *
- * is_corked:	Boolean flag indicating whether the cache entry associated
- *		with an object is corked or not corked.
- *
  * is_dirty:	Boolean flag indicating whether the contents of the cache
  *		entry has been modified since the last time it was written
  *		to disk.
@@ -1609,9 +1588,6 @@ typedef struct H5C_cache_entry_t {
     void  		      *	image_ptr;
     hbool_t			image_up_to_date;
     const H5C_class_t	      *	type;
-    haddr_t		        tag;
-    H5C_tag_globality_t		globality;
-    hbool_t			is_corked;
     hbool_t			is_dirty;
     hbool_t			dirtied;
     hbool_t			is_protected;
@@ -1655,6 +1631,11 @@ typedef struct H5C_cache_entry_t {
     struct H5C_cache_entry_t  *	coll_prev;
 #endif /* H5_HAVE_PARALLEL */
 
+    /* fields supporting tag lists */
+    struct H5C_cache_entry_t  *	tl_next;
+    struct H5C_cache_entry_t  *	tl_prev;
+    struct H5C_tag_info_t     * tag_info;
+
 #if H5C_COLLECT_CACHE_ENTRY_STATS
     /* cache entry stats fields */
     int32_t			accesses;
@@ -1980,7 +1961,7 @@ H5_DLL herr_t H5C_flush_tagged_entries(H5F_t * f, hid_t dxpl_id, haddr_t tag);
 H5_DLL herr_t H5C_evict_tagged_entries(H5F_t * f, hid_t dxpl_id, haddr_t tag, hbool_t match_global);
 H5_DLL herr_t H5C_expunge_tag_type_metadata(H5F_t *f, hid_t dxpl_id, haddr_t tag, int type_id, unsigned flags);
 #if H5C_DO_TAGGING_SANITY_CHECKS
-herr_t H5C_verify_tag(int id, haddr_t tag, H5C_tag_globality_t globality);
+herr_t H5C_verify_tag(int id, haddr_t tag);
 #endif
 H5_DLL herr_t H5C_flush_to_min_clean(H5F_t *f, hid_t dxpl_id);
 H5_DLL herr_t H5C_get_cache_auto_resize_config(const H5C_t *cache_ptr,
diff --git a/src/H5Cquery.c b/src/H5Cquery.c
index 874b12f..be0d4fa 100644
--- a/src/H5Cquery.c
+++ b/src/H5Cquery.c
@@ -275,7 +275,7 @@ H5C_get_entry_status(const H5F_t *f,
         if(is_pinned_ptr != NULL)
             *is_pinned_ptr = entry_ptr->is_pinned;
         if(is_corked_ptr != NULL)
-            *is_corked_ptr = entry_ptr->is_corked;
+            *is_corked_ptr = entry_ptr->tag_info ? entry_ptr->tag_info->corked : FALSE;
         if(is_flush_dep_parent_ptr != NULL)
             *is_flush_dep_parent_ptr = (entry_ptr->flush_dep_nchildren > 0);
         if(is_flush_dep_child_ptr != NULL)
diff --git a/src/H5Ctag.c b/src/H5Ctag.c
index 8ee287c..b03d2a6 100644
--- a/src/H5Ctag.c
+++ b/src/H5Ctag.c
@@ -62,11 +62,6 @@ typedef struct {
     hbool_t pinned_entries_need_evicted;        /* Flag to indicate that a pinned entry was attempted to be evicted */
 } H5C_tag_iter_evict_ctx_t;
 
-/* Typedef for tagged entry iterator callback context - retag tagged entries */
-typedef struct {
-    haddr_t dest_tag;                   /* New tag value for matching entries */
-} H5C_tag_iter_retag_ctx_t;
-
 /* Typedef for tagged entry iterator callback context - expunge tag type metadata */
 typedef struct {
     H5F_t * f;                          /* File pointer for evicting entry */
@@ -91,6 +86,9 @@ static herr_t H5C__mark_tagged_entries(H5C_t *cache_ptr, haddr_t tag);
 /* Package Variables */
 /*********************/
 
+/* Declare extern free list to manage the tag info struct */
+H5FL_EXTERN(H5C_tag_info_t);
+
 
 /*****************************/
 /* Library Private Variables */
@@ -188,7 +186,8 @@ herr_t
 H5C__tag_entry(H5C_t *cache, H5C_cache_entry_t *entry, hid_t dxpl_id)
 {
     H5P_genplist_t *dxpl;       /* dataset transfer property list */
-    H5C_tag_t tag;              /* Tag structure */
+    H5C_tag_info_t *tag_info;	/* Points to a tag info struct */
+    haddr_t tag;                /* Tag value */
     herr_t ret_value = SUCCEED;  /* Return value */
 
     FUNC_ENTER_PACKAGE
@@ -203,7 +202,7 @@ H5C__tag_entry(H5C_t *cache, H5C_cache_entry_t *entry, hid_t dxpl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list")
 
     /* Get the tag from the DXPL */
-    if((H5P_get(dxpl, "H5C_tag", &tag)) < 0)
+    if((H5P_get(dxpl, H5AC_TAG_NAME, &tag)) < 0)
 	HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to query property value")
 
     if(cache->ignore_tags) {
@@ -214,24 +213,48 @@ H5C__tag_entry(H5C_t *cache, H5C_cache_entry_t *entry, hid_t dxpl_id)
            arbitrarily set it to something for the sake of passing the tests. 
            If the tag value is set, then we'll just let it get assigned without
            additional checking for correctness. */
-        if(!tag.value) {
-            tag.value = H5AC__IGNORE_TAG;
-            tag.globality = H5C_GLOBALITY_NONE;
-        } /* end if */
+        if(!H5F_addr_defined(tag))
+            tag = H5AC__IGNORE_TAG;
     } /* end if */
 #if H5C_DO_TAGGING_SANITY_CHECKS
     else {
         /* Perform some sanity checks to ensure that a correct tag is being applied */
-        if(H5C_verify_tag(entry->type->id, tag.value, tag.globality) < 0)
+        if(H5C_verify_tag(entry->type->id, tag) < 0)
             HGOTO_ERROR(H5E_CACHE, H5E_CANTTAG, FAIL, "tag verification failed")
     } /* end else */
 #endif
 
-    /* Apply the tag to the entry */
-    entry->tag = tag.value;
+    /* Search the list of tagged object addresses in the cache */
+    tag_info = (H5C_tag_info_t *)H5SL_search(cache->tag_list, &tag);
+
+    /* Check if this is the first entry for this tagged object */
+    if(NULL == tag_info) {
+        /* Allocate new tag info struct */
+        if(NULL == (tag_info = H5FL_CALLOC(H5C_tag_info_t)))
+            HGOTO_ERROR(H5E_CACHE, H5E_CANTALLOC, FAIL, "can't allocate tag info for cache entry")
+
+        /* Set the tag for all entries */
+        tag_info->tag = tag;
+
+        /* Insert tag info into skip list */
+        if(H5SL_insert(cache->tag_list, tag_info, &(tag_info->tag)) < 0 )
+            HGOTO_ERROR(H5E_CACHE, H5E_CANTINSERT, FAIL, "can't insert tag info in skip list")
+    } /* end if */
+    else
+        HDassert(tag_info->corked || (tag_info->entry_cnt > 0 && tag_info->head));
+
+    /* Sanity check entry, to avoid double insertions, etc */
+    HDassert(entry->tl_next == NULL);
+    HDassert(entry->tl_prev == NULL);
+    HDassert(entry->tag_info == NULL);
 
-    /* Apply the tag globality to the entry */
-    entry->globality = tag.globality;
+    /* Add the entry to the list for the tagged object */
+    entry->tl_next = tag_info->head;
+    entry->tag_info = tag_info;
+    if(tag_info->head)
+        tag_info->head->tl_prev = entry;
+    tag_info->head = entry;
+    tag_info->entry_cnt++;
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -240,7 +263,70 @@ done:
 
 /*-------------------------------------------------------------------------
  *
- * Function:    H5C_iter_tagged_entries
+ * Function:    H5C__untag_entry
+ *
+ * Purpose:     Removes an entry from a tag list, possibly removing the tag
+ *		info from the list of tagged objects with entries.
+ *
+ * Return:      FAIL if error is detected, SUCCEED otherwise.
+ *
+ * Programmer:  Quincey Koziol
+ *              July 8, 2016
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5C__untag_entry(H5C_t *cache, H5C_cache_entry_t *entry)
+{
+    H5C_tag_info_t *tag_info;	/* Points to a tag info struct */
+    herr_t ret_value = SUCCEED;  /* Return value */
+
+    FUNC_ENTER_PACKAGE
+
+    /* Assertions */
+    HDassert(cache != NULL);
+    HDassert(entry != NULL);
+    HDassert(cache->magic == H5C__H5C_T_MAGIC);
+
+    /* Get the entry's tag info struct */
+    if(NULL != (tag_info = entry->tag_info)) {
+        /* Remove the entry from the list */
+        if(entry->tl_next)
+            entry->tl_next->tl_prev = entry->tl_prev;
+        if(entry->tl_prev)
+            entry->tl_prev->tl_next = entry->tl_next;
+        if(tag_info->head == entry)
+            tag_info->head = entry->tl_next;
+        tag_info->entry_cnt--;
+
+        /* Reset pointers, to avoid confusion */
+        entry->tl_next = NULL;
+        entry->tl_prev = NULL;
+        entry->tag_info = NULL;
+
+        /* Remove the tag info from the tag list, if there's no more entries with this tag */
+        if(!tag_info->corked && 0 == tag_info->entry_cnt) {
+            /* Sanity check */
+            HDassert(NULL == tag_info->head);
+
+            if(H5SL_remove(cache->tag_list, &(tag_info->tag)) != tag_info)
+                HGOTO_ERROR(H5E_CACHE, H5E_CANTREMOVE, FAIL, "can't remove tag info from list")
+
+            /* Release the tag info */
+            tag_info = H5FL_FREE(H5C_tag_info_t, tag_info);
+        } /* end if */
+        else
+            HDassert(tag_info->corked || NULL != tag_info->head);
+    } /* end if */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5C__untag_entry */
+
+
+/*-------------------------------------------------------------------------
+ *
+ * Function:    H5C__iter_tagged_entries_real
  *
  * Purpose:     Iterate over tagged entries, making a callback for matches
  *
@@ -251,39 +337,92 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-int
-H5C__iter_tagged_entries(H5C_t *cache, haddr_t tag, hbool_t match_global,
-    H5C_tag_iter_cb_t cb, void *cb_ctx)
+static herr_t
+H5C__iter_tagged_entries_real(H5C_t *cache, haddr_t tag, H5C_tag_iter_cb_t cb,
+    void *cb_ctx)
 {
-    unsigned u;                         /* Local index variable */
-    int ret_value = H5_ITER_CONT;       /* Return value */
+    H5C_tag_info_t *tag_info;	        /* Points to a tag info struct */
+    herr_t ret_value = SUCCEED;         /* Return value */
 
     /* Function enter macro */
-    FUNC_ENTER_PACKAGE
+    FUNC_ENTER_STATIC
 
     /* Sanity checks */
     HDassert(cache != NULL);
     HDassert(cache->magic == H5C__H5C_T_MAGIC);
 
-    /* Iterate through entries in the index. */
-    for(u = 0; u < H5C__HASH_TABLE_LEN; u++) {
+    /* Search the list of tagged object addresses in the cache */
+    tag_info = (H5C_tag_info_t *)H5SL_search(cache->tag_list, &tag);
+
+    /* If there's any entries for this tag, iterate over them */
+    if(tag_info) {
         H5C_cache_entry_t *entry;       /* Pointer to current entry */
         H5C_cache_entry_t *next_entry;  /* Pointer to next entry in hash bucket chain */
 
-        next_entry = cache->index[u];
-        while(next_entry != NULL) {
-            /* Acquire pointer to current entry and to next entry */
+        /* Sanity check */
+        HDassert(tag_info->head);
+        HDassert(tag_info->entry_cnt > 0);
+
+        /* Iterate over the entries for this tag */
+        entry = tag_info->head;
+        while(entry) {
+            /* Acquire pointer to next entry */
+            next_entry = entry->tl_next;
+
+            /* Make callback for entry */
+            if((cb)(entry, cb_ctx) != H5_ITER_CONT)
+                HGOTO_ERROR(H5E_CACHE, H5E_BADITER, FAIL, "tagged entry iteration callback failed")
+            
+            /* Advance to next entry */
             entry = next_entry;
-            next_entry = entry->ht_next;
-
-            /* Check for entry matching tag and/or globality */
-            if((entry->tag == tag) || (match_global && entry->globality == H5C_GLOBALITY_MAJOR)) {
-                /* Make callback for entry */
-                if((ret_value = (cb)(entry, cb_ctx)) != H5_ITER_CONT)
-                    HGOTO_ERROR(H5E_CACHE, H5E_BADITER, H5_ITER_ERROR, "Iteration of tagged entries failed")
-            } /* end if */
         } /* end while */
-    } /* end for */
+    } /* end if */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5C__iter_tagged_entries_real() */
+
+
+/*-------------------------------------------------------------------------
+ *
+ * Function:    H5C__iter_tagged_entries
+ *
+ * Purpose:     Iterate over tagged entries, making a callback for matches
+ *
+ * Return:      FAIL if error is detected, SUCCEED otherwise.
+ *
+ * Programmer:  Quincey Koziol
+ *              June 7, 2016
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5C__iter_tagged_entries(H5C_t *cache, haddr_t tag, hbool_t match_global,
+    H5C_tag_iter_cb_t cb, void *cb_ctx)
+{
+    herr_t ret_value = SUCCEED;       /* Return value */
+
+    /* Function enter macro */
+    FUNC_ENTER_PACKAGE
+
+    /* Sanity checks */
+    HDassert(cache != NULL);
+    HDassert(cache->magic == H5C__H5C_T_MAGIC);
+
+    /* Iterate over the entries for this tag */
+    if(H5C__iter_tagged_entries_real(cache, tag, cb, cb_ctx) < 0)
+        HGOTO_ERROR(H5E_CACHE, H5E_BADITER, FAIL, "iteration of tagged entries failed")
+
+    /* Check for iterating over global metadata */
+    if(match_global) { 
+        /* Iterate over the entries for SOHM entries */
+        if(H5C__iter_tagged_entries_real(cache, H5AC__SOHM_TAG, cb, cb_ctx) < 0)
+            HGOTO_ERROR(H5E_CACHE, H5E_BADITER, FAIL, "iteration of tagged entries failed")
+    
+        /* Iterate over the entries for global heap entries */
+        if(H5C__iter_tagged_entries_real(cache, H5AC__GLOBALHEAP_TAG, cb, cb_ctx) < 0)
+            HGOTO_ERROR(H5E_CACHE, H5E_BADITER, FAIL, "iteration of tagged entries failed")
+    } /* end if */
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -476,7 +615,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5C_verify_tag(int id, haddr_t tag, H5C_tag_globality_t globality)
+H5C_verify_tag(int id, haddr_t tag)
 {
     herr_t ret_value = SUCCEED;
 
@@ -498,8 +637,6 @@ H5C_verify_tag(int id, haddr_t tag, H5C_tag_globality_t globality)
         if((id == H5AC_SUPERBLOCK_ID) || (id == H5AC_DRVRINFO_ID)) {
             if(tag != H5AC__SUPERBLOCK_TAG)
                 HGOTO_ERROR(H5E_CACHE, H5E_CANTTAG, FAIL, "superblock not tagged with H5AC__SUPERBLOCK_TAG")
-            if(globality != H5C_GLOBALITY_MAJOR)
-                HGOTO_ERROR(H5E_CACHE, H5E_CANTTAG, FAIL, "superblock/driver-info globality not marked with H5C_GLOBALITY_MAJOR")
         } /* end if */
         else {
             if(tag == H5AC__SUPERBLOCK_TAG)
@@ -510,8 +647,6 @@ H5C_verify_tag(int id, haddr_t tag, H5C_tag_globality_t globality)
         if((id == H5AC_FSPACE_HDR_ID) || (id == H5AC_FSPACE_SINFO_ID)) {
             if(tag != H5AC__FREESPACE_TAG)
                 HGOTO_ERROR(H5E_CACHE, H5E_CANTTAG, FAIL, "freespace entry not tagged with H5AC__FREESPACE_TAG")
-            if(globality != H5C_GLOBALITY_MINOR)
-                HGOTO_ERROR(H5E_CACHE, H5E_CANTTAG, FAIL, "freespace entry globality not marked with H5C_GLOBALITY_MINOR")
         } /* end if */
         else {
             if(tag == H5AC__FREESPACE_TAG)
@@ -522,16 +657,12 @@ H5C_verify_tag(int id, haddr_t tag, H5C_tag_globality_t globality)
         if((id == H5AC_SOHM_TABLE_ID) || (id == H5AC_SOHM_LIST_ID)) { 
             if(tag != H5AC__SOHM_TAG)
                 HGOTO_ERROR(H5E_CACHE, H5E_CANTTAG, FAIL, "sohm entry not tagged with H5AC__SOHM_TAG")
-            if(globality != H5C_GLOBALITY_MAJOR)
-                HGOTO_ERROR(H5E_CACHE, H5E_CANTTAG, FAIL, "sohm entry globality not marked with H5C_GLOBALITY_MAJOR")
         } /* end if */
     
         /* Global Heap */
         if(id == H5AC_GHEAP_ID) {
             if(tag != H5AC__GLOBALHEAP_TAG)
                 HGOTO_ERROR(H5E_CACHE, H5E_CANTTAG, FAIL, "global heap not tagged with H5AC__GLOBALHEAP_TAG")
-            if(globality != H5C_GLOBALITY_MAJOR)
-                HGOTO_ERROR(H5E_CACHE, H5E_CANTTAG, FAIL, "global heap entry globality not marked with H5C_GLOBALITY_MAJOR")
         } /* end if */
         else {
             if(tag == H5AC__GLOBALHEAP_TAG)
@@ -589,37 +720,6 @@ done:
 
 /*-------------------------------------------------------------------------
  *
- * Function:    H5C__retag_entries_cb
- *
- * Purpose:     Change tag for entries that match current tag
- *
- * Return:      H5_ITER_CONT (can't fail)
- *
- * Programmer:  Mike McGreevy
- *              March 17, 2010
- *
- *-------------------------------------------------------------------------
- */
-static int
-H5C__retag_entries_cb(H5C_cache_entry_t *entry, void *_ctx)
-{
-    H5C_tag_iter_retag_ctx_t *ctx = (H5C_tag_iter_retag_ctx_t *)_ctx; /* Get pointer to iterator context */
-
-    /* Function enter macro */
-    FUNC_ENTER_STATIC_NOERR
-
-    /* Santify checks */
-    HDassert(entry);
-    HDassert(ctx);
-
-    entry->tag = ctx->dest_tag;
-
-    FUNC_LEAVE_NOAPI(H5_ITER_CONT)
-} /* H5C_retag_entries_cb() */
-
-
-/*-------------------------------------------------------------------------
- *
  * Function:    H5C_retag_entries
  *
  * Purpose:     Searches through cache index for all entries with the
@@ -636,7 +736,7 @@ H5C__retag_entries_cb(H5C_cache_entry_t *entry, void *_ctx)
 herr_t
 H5C_retag_entries(H5C_t *cache, haddr_t src_tag, haddr_t dest_tag) 
 {
-    H5C_tag_iter_retag_ctx_t ctx;       /* Iterator callback context */
+    H5C_tag_info_t *tag_info;	        /* Points to a tag info struct */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     /* Function enter macro */
@@ -645,12 +745,15 @@ H5C_retag_entries(H5C_t *cache, haddr_t src_tag, haddr_t dest_tag)
     /* Sanity check */
     HDassert(cache);
 
-    /* Construct context for iterator callbacks */
-    ctx.dest_tag = dest_tag;
+    /* Remove tag info from tag list */
+    if(NULL != (tag_info = (H5C_tag_info_t *)H5SL_remove(cache->tag_list, &src_tag))) {
+        /* Change to new tag */
+        tag_info->tag = dest_tag;
 
-    /* Iterate through entries, retagging those with the src_tag tag */
-    if(H5C__iter_tagged_entries(cache, src_tag, FALSE, H5C__retag_entries_cb, &ctx) < 0)
-        HGOTO_ERROR(H5E_CACHE, H5E_BADITER, FAIL, "Iteration of tagged entries failed")
+        /* Re-insert tag info into skip list */
+        if(H5SL_insert(cache->tag_list, tag_info, &(tag_info->tag)) < 0)
+            HGOTO_ERROR(H5E_CACHE, H5E_CANTINSERT, FAIL, "can't insert tag info in skip list")
+    } /* end if */
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -740,73 +843,3 @@ done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* H5C_expunge_tag_type_metadata() */
 
-
-/*-------------------------------------------------------------------------
- * Function:    H5C__mark_tagged_entries_cork_cb
- *		
- * Purpose:     The "is_corked" field to "val" for en entry
- *
- * Return:      H5_ITER_ERROR if error is detected, H5_ITER_CONT otherwise.
- *
- * Programmer:  Vailin Choi
- *		January 2014
- *
- *-------------------------------------------------------------------------
- */
-static int
-H5C__mark_tagged_entries_cork_cb(H5C_cache_entry_t *entry, void *_ctx)
-{
-    H5C_tag_iter_cork_ctx_t *ctx = (H5C_tag_iter_cork_ctx_t *)_ctx; /* Get pointer to iterator context */
-
-    /* Function enter macro */
-    FUNC_ENTER_STATIC_NOERR
-
-    /* Santify checks */
-    HDassert(entry);
-    HDassert(ctx);
-
-    /* Set the entry's "corked" field to "val" */
-    entry->is_corked = ctx->cork_val;
-
-    FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5C__mark_tagged_entries_cork_cb() */
-
-
-/*-------------------------------------------------------------------------
- * Function:    H5C__mark_tagged_entries_cork
- *		
- * Purpose:     To set the "is_corked" field to "val" for entries in cache 
- *		with the entry's tag equals to "obj_addr".
- *
- * Return:      FAIL if error is detected, SUCCEED otherwise.
- *
- * Programmer:  Vailin Choi
- *		January 2014
- *
- *-------------------------------------------------------------------------
- */
-herr_t 
-H5C__mark_tagged_entries_cork(H5C_t *cache, haddr_t obj_addr, hbool_t val)
-{
-    H5C_tag_iter_cork_ctx_t ctx;        /* Context for iterator callback */
-    herr_t ret_value = SUCCEED;         /* Return value */
-
-    /* Function enter macro */
-    FUNC_ENTER_PACKAGE
-
-    /* Sanity checks */
-    HDassert(cache);
-    HDassert(cache->magic == H5C__H5C_T_MAGIC);
-
-    /* Construct context for iterator callbacks */
-    ctx.cork_val = val;
-
-    /* Iterate through entries, find each entry with the specified tag */
-    /* and set the entry's "corked" field to "val" */
-    if(H5C__iter_tagged_entries(cache, obj_addr, FALSE, H5C__mark_tagged_entries_cork_cb, &ctx) < 0)
-        HGOTO_ERROR(H5E_CACHE, H5E_BADITER, FAIL, "Iteration of tagged entries failed")
-
-done:
-    FUNC_LEAVE_NOAPI(ret_value)
-} /* H5C__mark_tagged_entries_cork() */
-
diff --git a/src/H5Ctest.c b/src/H5Ctest.c
index b049a75..876b63a 100644
--- a/src/H5Ctest.c
+++ b/src/H5Ctest.c
@@ -97,6 +97,7 @@ static int
 H5C__verify_cork_tag_test_cb(H5C_cache_entry_t *entry, void *_ctx)
 {
     H5C_tag_iter_vct_ctx_t *ctx = (H5C_tag_iter_vct_ctx_t *)_ctx; /* Get pointer to iterator context */
+    hbool_t is_corked;                  /* Corked status for entry */
     int ret_value = H5_ITER_CONT;       /* Return value */
 
     /* Function enter macro */
@@ -106,8 +107,11 @@ H5C__verify_cork_tag_test_cb(H5C_cache_entry_t *entry, void *_ctx)
     HDassert(entry);
     HDassert(ctx);
 
+    /* Retrieve corked status for entry */
+    is_corked = entry->tag_info ? entry->tag_info->corked : FALSE;
+
     /* Verify corked status for entry */
-    if(entry->is_corked != ctx->status)
+    if(is_corked != ctx->status)
         HGOTO_ERROR(H5E_CACHE, H5E_BADVALUE, H5_ITER_ERROR, "bad cork status")
 
 done:
diff --git a/src/H5Fpkg.h b/src/H5Fpkg.h
index 4d324d1..8d7dcbd 100644
--- a/src/H5Fpkg.h
+++ b/src/H5Fpkg.h
@@ -404,6 +404,7 @@ H5_DLL herr_t H5F_get_sohm_mesg_count_test(hid_t fid, unsigned type_id,
     size_t *mesg_count);
 H5_DLL herr_t H5F_check_cached_stab_test(hid_t file_id);
 H5_DLL herr_t H5F_get_maxaddr_test(hid_t file_id, haddr_t *maxaddr);
+H5_DLL herr_t H5F_get_sbe_addr_test(hid_t file_id, haddr_t *sbe_addr);
 #endif /* H5F_TESTING */
 
 #endif /* _H5Fpkg_H */
diff --git a/src/H5Ftest.c b/src/H5Ftest.c
index 344d7c1..e3760b7 100644
--- a/src/H5Ftest.c
+++ b/src/H5Ftest.c
@@ -186,3 +186,37 @@ done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5F_get_maxaddr_test() */
 
+
+/*-------------------------------------------------------------------------
+ * Function:	H5F_get_sbe_addr_test
+ *
+ * Purpose:     Retrieve the address of a superblock extension's object header
+ *		for a file
+ *
+ * Return:	Success:        Non-negative
+ *		Failure:	Negative
+ *
+ * Programmer:	Quincey Koziol
+ *	        Jul 10, 2016
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5F_get_sbe_addr_test(hid_t file_id, haddr_t *sbe_addr)
+{
+    H5F_t	*file;                  /* File info */
+    herr_t	ret_value = SUCCEED;    /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT
+
+    /* Check arguments */
+    if(NULL == (file = (H5F_t *)H5I_object_verify(file_id, H5I_FILE)))
+	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file")
+
+    /* Retrieve maxaddr for file */
+    *sbe_addr = file->shared->sblock->ext_addr;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5F_get_sbe_addr_test() */
+
diff --git a/src/H5Pdxpl.c b/src/H5Pdxpl.c
index e685c65..c094c20 100644
--- a/src/H5Pdxpl.c
+++ b/src/H5Pdxpl.c
@@ -273,7 +273,7 @@ static const void *H5D_def_vlen_alloc_info_g = H5D_XFER_VLEN_ALLOC_INFO_DEF;   /
 static const H5MM_free_t H5D_def_vlen_free_g = H5D_XFER_VLEN_FREE_DEF;         /* Default value for vlen free function */
 static const void *H5D_def_vlen_free_info_g = H5D_XFER_VLEN_FREE_INFO_DEF;     /* Default value for vlen free information */
 static const size_t H5D_def_hyp_vec_size_g = H5D_XFER_HYPER_VECTOR_SIZE_DEF;   /* Default value for vector size */
-static const H5C_tag_t H5D_def_tag_g = H5C_TAG_DEF;                            /* Default value for cache entry tag */
+static const haddr_t H5D_def_tag_g = H5AC_TAG_DEF;                              /* Default value for cache entry tag */
 static const H5FD_mpio_xfer_t H5D_def_io_xfer_mode_g = H5D_XFER_IO_XFER_MODE_DEF;      /* Default value for I/O transfer mode */
 static const H5FD_mpio_chunk_opt_t H5D_def_mpio_chunk_opt_mode_g = H5D_XFER_MPIO_CHUNK_OPT_HARD_DEF;
 static const H5FD_mpio_collective_opt_t H5D_def_mpio_collective_opt_mode_g = H5D_XFER_MPIO_COLLECTIVE_OPT_DEF;
@@ -326,7 +326,7 @@ H5P__dxfr_reg_prop(H5P_genclass_t *pclass)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, FAIL, "can't insert property into class")
 
     /* Register the cache tag property */
-    if(H5P_register_real(pclass, H5C_TAG_NAME, H5C_TAG_SIZE, &H5D_def_tag_g,
+    if(H5P_register_real(pclass, H5AC_TAG_NAME, H5AC_TAG_SIZE, &H5D_def_tag_g,
             NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL) < 0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, FAIL, "can't insert property into class")