commit 7ecb10d515980f592a3bd7fb27f883af8404d762
Author:     Alvaro Herrera <alvherre@alvh.no-ip.org>
AuthorDate: Tue May 24 19:09:37 2016 -0400
CommitDate: Tue May 24 19:10:01 2016 -0400

    fix PageAddItem BRIN bug

diff --git a/src/backend/access/brin/brin_pageops.c b/src/backend/access/brin/brin_pageops.c
index d0ca485..a49eccd 100644
--- a/src/backend/access/brin/brin_pageops.c
+++ b/src/backend/access/brin/brin_pageops.c
@@ -179,8 +179,9 @@ brin_doupdate(Relation idxrel, BlockNumber pagesPerRange,
 
 		START_CRIT_SECTION();
 		PageIndexDeleteNoCompact(oldpage, &oldoff, 1);
-		if (PageAddItem(oldpage, (Item) newtup, newsz, oldoff, true,
-						false) == InvalidOffsetNumber)
+		if (PageAddItemFlags(oldpage, (Item) newtup, newsz, oldoff,
+							 PAI_OVERWRITE | PAI_ALLOW_LARGE_OFFSET) ==
+			InvalidOffsetNumber)
 			elog(ERROR, "failed to add BRIN tuple");
 		MarkBufferDirty(oldbuf);
 
diff --git a/src/backend/storage/page/bufpage.c b/src/backend/storage/page/bufpage.c
index 0189bc9..cc7a4d8 100644
--- a/src/backend/storage/page/bufpage.c
+++ b/src/backend/storage/page/bufpage.c
@@ -153,12 +153,12 @@ PageIsVerified(Page page, BlockNumber blkno)
 
 
 /*
- *	PageAddItem
+ *	PageAddItemFlags
  *
  *	Add an item to a page.  Return value is offset at which it was
  *	inserted, or InvalidOffsetNumber if there's not room to insert.
  *
- *	If overwrite is true, we just store the item at the specified
+ *	If flag PAI_OVERWRITE is set, we just store the item at the specified
  *	offsetNumber (which must be either a currently-unused item pointer,
  *	or one past the last existing item).  Otherwise,
  *	if offsetNumber is valid and <= current max offset in the page,
@@ -167,18 +167,20 @@ PageIsVerified(Page page, BlockNumber blkno)
  *	If offsetNumber is not valid, then assign one by finding the first
  *	one that is both unused and deallocated.
  *
- *	If is_heap is true, we enforce that there can't be more than
+ *	If flag PAI_IS_HEAP is set, we enforce that there can't be more than
  *	MaxHeapTuplesPerPage line pointers on the page.
  *
+ *	If flag PAI_ALLOW_LARGE_OFFSET is not set, we disallow placing items
+ *	beyond one past the last existing item.
+ *
  *	!!! EREPORT(ERROR) IS DISALLOWED HERE !!!
  */
 OffsetNumber
-PageAddItem(Page page,
-			Item item,
-			Size size,
-			OffsetNumber offsetNumber,
-			bool overwrite,
-			bool is_heap)
+PageAddItemFlags(Page page,
+				 Item item,
+				 Size size,
+				 OffsetNumber offsetNumber,
+				 int flags)
 {
 	PageHeader	phdr = (PageHeader) page;
 	Size		alignedSize;
@@ -209,7 +211,7 @@ PageAddItem(Page page,
 	if (OffsetNumberIsValid(offsetNumber))
 	{
 		/* yes, check it */
-		if (overwrite)
+		if ((flags & PAI_OVERWRITE) != 0)
 		{
 			if (offsetNumber < limit)
 			{
@@ -257,13 +259,18 @@ PageAddItem(Page page,
 		}
 	}
 
-	if (offsetNumber > limit)
+	/*
+	 * Reject placing items beyond the first unused line pointer, unless
+	 * caller explicitely asked for that.
+	 */
+	if (((flags & PAI_ALLOW_LARGE_OFFSET) == 0) && offsetNumber > limit)
 	{
 		elog(WARNING, "specified item offset is too large");
 		return InvalidOffsetNumber;
 	}
 
-	if (is_heap && offsetNumber > MaxHeapTuplesPerPage)
+	/* Reject placing items beyond heap boundary, if heap */
+	if (((flags & PAI_IS_HEAP) != 0) && offsetNumber > MaxHeapTuplesPerPage)
 	{
 		elog(WARNING, "can't put more than MaxHeapTuplesPerPage items in a heap page");
 		return InvalidOffsetNumber;
@@ -324,6 +331,21 @@ PageAddItem(Page page,
 }
 
 /*
+ * PageAddItemFlags shim, for compatibility.
+ */
+OffsetNumber
+PageAddItem(Page page, Item item, Size size, OffsetNumber offsetNumber,
+			bool overwrite, bool is_heap)
+{
+	int		flags = 0;
+
+	flags |= overwrite ? PAI_OVERWRITE : 0;
+	flags |= is_heap ? PAI_IS_HEAP : 0;
+
+	return PageAddItemFlags(page, item, size, offsetNumber, flags);
+}
+
+/*
  * PageGetTempPage
  *		Get a temporary page in local memory for special processing.
  *		The returned page is not initialized at all; caller must do that.
diff --git a/src/include/storage/bufpage.h b/src/include/storage/bufpage.h
index 63053d4..5ca1db7 100644
--- a/src/include/storage/bufpage.h
+++ b/src/include/storage/bufpage.h
@@ -407,11 +407,16 @@ do { \
  *		extern declarations
  * ----------------------------------------------------------------
  */
+#define PAI_OVERWRITE			(1 << 0)
+#define PAI_IS_HEAP				(1 << 1)
+#define PAI_ALLOW_LARGE_OFFSET	(1 << 2)
 
 extern void PageInit(Page page, Size pageSize, Size specialSize);
 extern bool PageIsVerified(Page page, BlockNumber blkno);
 extern OffsetNumber PageAddItem(Page page, Item item, Size size,
 			OffsetNumber offsetNumber, bool overwrite, bool is_heap);
+extern OffsetNumber PageAddItemFlags(Page page, Item item, Size size,
+				 OffsetNumber offsetNumber, int flags);
 extern Page PageGetTempPage(Page page);
 extern Page PageGetTempPageCopy(Page page);
 extern Page PageGetTempPageCopySpecial(Page page);