Revert no-op changes to BufferGetPage()

The reverted changes were intended to force a choice of whether any
newly-added BufferGetPage() calls needed to be accompanied by a
test of the snapshot age, to support the "snapshot too old"
feature.  Such an accompanying test is needed in about 7% of the
cases, where the page is being used as part of a scan rather than
positioning for other purposes (such as DML or vacuuming).  The
additional effort required for back-patching, and the doubt whether
the intended benefit would really be there, have indicated it is
best just to rely on developers to do the right thing based on
comments and existing usage, as we do with many other conventions.

This change should have little or no effect on generated executable
code.

Motivated by the back-patching pain of Tom Lane and Robert Haas

6 files changed, 35 insertions, 52 deletions

diff --git a/src/backend/access/gist/gist.c b/src/backend/access/gist/gist.c
index 999e71cafca..996363c2ded 100644
--- a/src/backend/access/gist/gist.c
+++ b/src/backend/access/gist/gist.c
@@ -211,8 +211,7 @@ gistplacetopage(Relation rel, Size freespace, GISTSTATE *giststate,
 				bool markfollowright)
 {
 	BlockNumber blkno = BufferGetBlockNumber(buffer);
-	Page		page = BufferGetPage(buffer, NULL, NULL,
-									 BGP_NO_SNAPSHOT_TEST);
+	Page		page = BufferGetPage(buffer);
 	bool		is_leaf = (GistPageIsLeaf(page)) ? true : false;
 	XLogRecPtr	recptr;
 	int			i;
@@ -317,9 +316,7 @@ gistplacetopage(Relation rel, Size freespace, GISTSTATE *giststate,
 
 			dist->buffer = buffer;
 			dist->block.blkno = BufferGetBlockNumber(buffer);
-			dist->page =
-				PageGetTempPageCopySpecial(BufferGetPage(buffer, NULL, NULL,
-														 BGP_NO_SNAPSHOT_TEST));
+			dist->page = PageGetTempPageCopySpecial(BufferGetPage(buffer));
 
 			/* clean all flags except F_LEAF */
 			GistPageGetOpaque(dist->page)->flags = (is_leaf) ? F_LEAF : 0;
@@ -331,7 +328,7 @@ gistplacetopage(Relation rel, Size freespace, GISTSTATE *giststate,
 			/* Allocate new page */
 			ptr->buffer = gistNewBuffer(rel);
 			GISTInitBuffer(ptr->buffer, (is_leaf) ? F_LEAF : 0);
-			ptr->page = BufferGetPage(ptr->buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+			ptr->page = BufferGetPage(ptr->buffer);
 			ptr->block.blkno = BufferGetBlockNumber(ptr->buffer);
 		}
 
@@ -357,10 +354,7 @@ gistplacetopage(Relation rel, Size freespace, GISTSTATE *giststate,
 			int			i;
 
 			rootpg.buffer = buffer;
-			rootpg.page =
-				PageGetTempPageCopySpecial(BufferGetPage(rootpg.buffer,
-														 NULL, NULL,
-														 BGP_NO_SNAPSHOT_TEST));
+			rootpg.page = PageGetTempPageCopySpecial(BufferGetPage(rootpg.buffer));
 			GistPageGetOpaque(rootpg.page)->flags = 0;
 
 			/* Prepare a vector of all the downlinks */
@@ -468,11 +462,8 @@ gistplacetopage(Relation rel, Size freespace, GISTSTATE *giststate,
 		 * The first page in the chain was a temporary working copy meant to
 		 * replace the old page. Copy it over the old page.
 		 */
-		PageRestoreTempPage(dist->page, BufferGetPage(dist->buffer,
-													  NULL, NULL,
-													  BGP_NO_SNAPSHOT_TEST));
-		dist->page = BufferGetPage(dist->buffer, NULL, NULL,
-								   BGP_NO_SNAPSHOT_TEST);
+		PageRestoreTempPage(dist->page, BufferGetPage(dist->buffer));
+		dist->page = BufferGetPage(dist->buffer);
 
 		/* Write the WAL record */
 		if (RelationNeedsWAL(rel))
@@ -563,8 +554,7 @@ gistplacetopage(Relation rel, Size freespace, GISTSTATE *giststate,
 	 */
 	if (BufferIsValid(leftchildbuf))
 	{
-		Page		leftpg = BufferGetPage(leftchildbuf, NULL, NULL,
-										   BGP_NO_SNAPSHOT_TEST);
+		Page		leftpg = BufferGetPage(leftchildbuf);
 
 		GistPageSetNSN(leftpg, recptr);
 		GistClearFollowRight(leftpg);
@@ -624,8 +614,7 @@ gistdoinsert(Relation r, IndexTuple itup, Size freespace, GISTSTATE *giststate)
 			gistcheckpage(state.r, stack->buffer);
 		}
 
-		stack->page = BufferGetPage(stack->buffer, NULL, NULL,
-									BGP_NO_SNAPSHOT_TEST);
+		stack->page = (Page) BufferGetPage(stack->buffer);
 		stack->lsn = PageGetLSN(stack->page);
 		Assert(!RelationNeedsWAL(state.r) || !XLogRecPtrIsInvalid(stack->lsn));
 
@@ -710,8 +699,7 @@ gistdoinsert(Relation r, IndexTuple itup, Size freespace, GISTSTATE *giststate)
 					LockBuffer(stack->buffer, GIST_UNLOCK);
 					LockBuffer(stack->buffer, GIST_EXCLUSIVE);
 					xlocked = true;
-					stack->page = BufferGetPage(stack->buffer, NULL, NULL,
-												BGP_NO_SNAPSHOT_TEST);
+					stack->page = (Page) BufferGetPage(stack->buffer);
 
 					if (PageGetLSN(stack->page) != stack->lsn)
 					{
@@ -775,8 +763,7 @@ gistdoinsert(Relation r, IndexTuple itup, Size freespace, GISTSTATE *giststate)
 				LockBuffer(stack->buffer, GIST_UNLOCK);
 				LockBuffer(stack->buffer, GIST_EXCLUSIVE);
 				xlocked = true;
-				stack->page = BufferGetPage(stack->buffer, NULL, NULL,
-											BGP_NO_SNAPSHOT_TEST);
+				stack->page = (Page) BufferGetPage(stack->buffer);
 				stack->lsn = PageGetLSN(stack->page);
 
 				if (stack->blkno == GIST_ROOT_BLKNO)
@@ -866,7 +853,7 @@ gistFindPath(Relation r, BlockNumber child, OffsetNumber *downlinkoffnum)
 		buffer = ReadBuffer(r, top->blkno);
 		LockBuffer(buffer, GIST_SHARE);
 		gistcheckpage(r, buffer);
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = (Page) BufferGetPage(buffer);
 
 		if (GistPageIsLeaf(page))
 		{
@@ -954,8 +941,7 @@ gistFindCorrectParent(Relation r, GISTInsertStack *child)
 	GISTInsertStack *parent = child->parent;
 
 	gistcheckpage(r, parent->buffer);
-	parent->page = BufferGetPage(parent->buffer, NULL, NULL,
-								 BGP_NO_SNAPSHOT_TEST);
+	parent->page = (Page) BufferGetPage(parent->buffer);
 
 	/* here we don't need to distinguish between split and page update */
 	if (child->downlinkoffnum == InvalidOffsetNumber ||
@@ -996,8 +982,7 @@ gistFindCorrectParent(Relation r, GISTInsertStack *child)
 			parent->buffer = ReadBuffer(r, parent->blkno);
 			LockBuffer(parent->buffer, GIST_EXCLUSIVE);
 			gistcheckpage(r, parent->buffer);
-			parent->page = BufferGetPage(parent->buffer, NULL, NULL,
-										 BGP_NO_SNAPSHOT_TEST);
+			parent->page = (Page) BufferGetPage(parent->buffer);
 		}
 
 		/*
@@ -1021,8 +1006,7 @@ gistFindCorrectParent(Relation r, GISTInsertStack *child)
 		while (ptr)
 		{
 			ptr->buffer = ReadBuffer(r, ptr->blkno);
-			ptr->page = BufferGetPage(ptr->buffer, NULL, NULL,
-									  BGP_NO_SNAPSHOT_TEST);
+			ptr->page = (Page) BufferGetPage(ptr->buffer);
 			ptr = ptr->parent;
 		}
 
@@ -1044,7 +1028,7 @@ static IndexTuple
 gistformdownlink(Relation rel, Buffer buf, GISTSTATE *giststate,
 				 GISTInsertStack *stack)
 {
-	Page		page = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+	Page		page = BufferGetPage(buf);
 	OffsetNumber maxoff;
 	OffsetNumber offset;
 	IndexTuple	downlink = NULL;
@@ -1125,7 +1109,7 @@ gistfixsplit(GISTInsertState *state, GISTSTATE *giststate)
 		GISTPageSplitInfo *si = palloc(sizeof(GISTPageSplitInfo));
 		IndexTuple	downlink;
 
-		page = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = BufferGetPage(buf);
 
 		/* Form the new downlink tuples to insert to parent */
 		downlink = gistformdownlink(state->r, buf, giststate, stack);
diff --git a/src/backend/access/gist/gistbuild.c b/src/backend/access/gist/gistbuild.c
index 8e7389c05f3..4e43a6932a4 100644
--- a/src/backend/access/gist/gistbuild.c
+++ b/src/backend/access/gist/gistbuild.c
@@ -169,7 +169,7 @@ gistbuild(Relation heap, Relation index, IndexInfo *indexInfo)
 	/* initialize the root page */
 	buffer = gistNewBuffer(index);
 	Assert(BufferGetBlockNumber(buffer) == GIST_ROOT_BLKNO);
-	page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+	page = BufferGetPage(buffer);
 
 	START_CRIT_SECTION();
 
@@ -589,7 +589,7 @@ gistProcessItup(GISTBuildState *buildstate, IndexTuple itup,
 		buffer = ReadBuffer(indexrel, blkno);
 		LockBuffer(buffer, GIST_EXCLUSIVE);
 
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = (Page) BufferGetPage(buffer);
 		childoffnum = gistchoose(indexrel, page, itup, giststate);
 		iid = PageGetItemId(page, childoffnum);
 		idxtuple = (IndexTuple) PageGetItem(page, iid);
@@ -699,8 +699,7 @@ gistbufferinginserttuples(GISTBuildState *buildstate, Buffer buffer, int level,
 	 */
 	if (is_split && BufferGetBlockNumber(buffer) == GIST_ROOT_BLKNO)
 	{
-		Page		page = BufferGetPage(buffer, NULL, NULL,
-										 BGP_NO_SNAPSHOT_TEST);
+		Page		page = BufferGetPage(buffer);
 		OffsetNumber off;
 		OffsetNumber maxoff;
 
@@ -867,7 +866,7 @@ gistBufferingFindCorrectParent(GISTBuildState *buildstate,
 	}
 
 	buffer = ReadBuffer(buildstate->indexrel, parent);
-	page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+	page = BufferGetPage(buffer);
 	LockBuffer(buffer, GIST_EXCLUSIVE);
 	gistcheckpage(buildstate->indexrel, buffer);
 	maxoff = PageGetMaxOffsetNumber(page);
@@ -1068,7 +1067,7 @@ gistGetMaxLevel(Relation index)
 		 * pro forma.
 		 */
 		LockBuffer(buffer, GIST_SHARE);
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = (Page) BufferGetPage(buffer);
 
 		if (GistPageIsLeaf(page))
 		{
@@ -1168,8 +1167,7 @@ gistMemorizeAllDownlinks(GISTBuildState *buildstate, Buffer parentbuf)
 	OffsetNumber maxoff;
 	OffsetNumber off;
 	BlockNumber parentblkno = BufferGetBlockNumber(parentbuf);
-	Page		page = BufferGetPage(parentbuf, NULL, NULL,
-									 BGP_NO_SNAPSHOT_TEST);
+	Page		page = BufferGetPage(parentbuf);
 
 	Assert(!GistPageIsLeaf(page));
 
diff --git a/src/backend/access/gist/gistget.c b/src/backend/access/gist/gistget.c
index 24af868466d..affd63535ad 100644
--- a/src/backend/access/gist/gistget.c
+++ b/src/backend/access/gist/gistget.c
@@ -54,7 +54,7 @@ gistkillitems(IndexScanDesc scan)
 
 	LockBuffer(buffer, GIST_SHARE);
 	gistcheckpage(scan->indexRelation, buffer);
-	page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+	page = BufferGetPage(buffer);
 
 	/*
 	 * If page LSN differs it means that the page was modified since the last read.
@@ -336,7 +336,8 @@ gistScanPage(IndexScanDesc scan, GISTSearchItem *pageItem, double *myDistances,
 	buffer = ReadBuffer(scan->indexRelation, pageItem->blkno);
 	LockBuffer(buffer, GIST_SHARE);
 	gistcheckpage(scan->indexRelation, buffer);
-	page = BufferGetPage(buffer, scan->xs_snapshot, r, BGP_TEST_FOR_OLD_SNAPSHOT);
+	page = BufferGetPage(buffer);
+	TestForOldSnapshot(scan->xs_snapshot, r, page);
 	opaque = GistPageGetOpaque(page);
 
 	/*
diff --git a/src/backend/access/gist/gistutil.c b/src/backend/access/gist/gistutil.c
index 5d16cf51e8f..fac166d4c29 100644
--- a/src/backend/access/gist/gistutil.c
+++ b/src/backend/access/gist/gistutil.c
@@ -701,7 +701,7 @@ GISTInitBuffer(Buffer b, uint32 f)
 	Size		pageSize;
 
 	pageSize = BufferGetPageSize(b);
-	page = BufferGetPage(b, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+	page = BufferGetPage(b);
 	PageInit(page, pageSize, sizeof(GISTPageOpaqueData));
 
 	opaque = GistPageGetOpaque(page);
@@ -718,7 +718,7 @@ GISTInitBuffer(Buffer b, uint32 f)
 void
 gistcheckpage(Relation rel, Buffer buf)
 {
-	Page		page = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+	Page		page = BufferGetPage(buf);
 
 	/*
 	 * ReadBuffer verifies that every newly-read page passes
@@ -776,7 +776,7 @@ gistNewBuffer(Relation r)
 		 */
 		if (ConditionalLockBuffer(buffer))
 		{
-			Page		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+			Page		page = BufferGetPage(buffer);
 
 			if (PageIsNew(page))
 				return buffer;	/* OK to use, if never initialized */
diff --git a/src/backend/access/gist/gistvacuum.c b/src/backend/access/gist/gistvacuum.c
index 9d9f5dcf41c..7947ff9dbe6 100644
--- a/src/backend/access/gist/gistvacuum.c
+++ b/src/backend/access/gist/gistvacuum.c
@@ -75,7 +75,7 @@ gistvacuumcleanup(IndexVacuumInfo *info, IndexBulkDeleteResult *stats)
 		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL,
 									info->strategy);
 		LockBuffer(buffer, GIST_SHARE);
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = (Page) BufferGetPage(buffer);
 
 		if (PageIsNew(page) || GistPageIsDeleted(page))
 		{
@@ -166,7 +166,7 @@ gistbulkdelete(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
 									RBM_NORMAL, info->strategy);
 		LockBuffer(buffer, GIST_SHARE);
 		gistcheckpage(rel, buffer);
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = (Page) BufferGetPage(buffer);
 
 		if (GistPageIsLeaf(page))
 		{
@@ -176,7 +176,7 @@ gistbulkdelete(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
 			LockBuffer(buffer, GIST_UNLOCK);
 			LockBuffer(buffer, GIST_EXCLUSIVE);
 
-			page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+			page = (Page) BufferGetPage(buffer);
 			if (stack->blkno == GIST_ROOT_BLKNO && !GistPageIsLeaf(page))
 			{
 				/* only the root can become non-leaf during relock */
diff --git a/src/backend/access/gist/gistxlog.c b/src/backend/access/gist/gistxlog.c
index 8ef6e98e7d4..b48e97cc66e 100644
--- a/src/backend/access/gist/gistxlog.c
+++ b/src/backend/access/gist/gistxlog.c
@@ -46,7 +46,7 @@ gistRedoClearFollowRight(XLogReaderState *record, uint8 block_id)
 	action = XLogReadBufferForRedo(record, block_id, &buffer);
 	if (action == BLK_NEEDS_REDO || action == BLK_RESTORED)
 	{
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = BufferGetPage(buffer);
 
 		GistPageSetNSN(page, lsn);
 		GistClearFollowRight(page);
@@ -78,7 +78,7 @@ gistRedoPageUpdateRecord(XLogReaderState *record)
 
 		data = begin = XLogRecGetBlockData(record, 0, &datalen);
 
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = (Page) BufferGetPage(buffer);
 
 		/* Delete old tuples */
 		if (xldata->ntodelete > 0)
@@ -199,7 +199,7 @@ gistRedoPageSplitRecord(XLogReaderState *record)
 		}
 
 		buffer = XLogInitBufferForRedo(record, i + 1);
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = (Page) BufferGetPage(buffer);
 		data = XLogRecGetBlockData(record, i + 1, &datalen);
 
 		tuples = decodePageSplitRecord(data, datalen, &num);
@@ -265,7 +265,7 @@ gistRedoCreateIndex(XLogReaderState *record)
 
 	buffer = XLogInitBufferForRedo(record, 0);
 	Assert(BufferGetBlockNumber(buffer) == GIST_ROOT_BLKNO);
-	page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+	page = (Page) BufferGetPage(buffer);
 
 	GISTInitBuffer(buffer, F_LEAF);