simplify_hash_bitmap_info_v3.patch

diff --git a/contrib/pageinspect/expected/hash.out b/contrib/pageinspect/expected/hash.out
index 7eb1537..fb0caee 100644
--- a/contrib/pageinspect/expected/hash.out
+++ b/contrib/pageinspect/expected/hash.out
@@ -30,23 +30,21 @@ hash_page_type | bitmap
 SELECT hash_page_type(get_raw_page('test_hash_a_idx', 6));
 ERROR:  block number 6 is out of range for relation "test_hash_a_idx"
 SELECT * FROM hash_bitmap_info('test_hash_a_idx', 0);
-ERROR:  page is not an overflow page
-DETAIL:  Expected 00000001, got 00000008.
+ERROR:  invalid overflow block number 0
 SELECT * FROM hash_bitmap_info('test_hash_a_idx', 1);
-ERROR:  page is not an overflow page
-DETAIL:  Expected 00000001, got 00000002.
+ERROR:  invalid overflow block number 1
 SELECT * FROM hash_bitmap_info('test_hash_a_idx', 2);
-ERROR:  page is not an overflow page
-DETAIL:  Expected 00000001, got 00000002.
+ERROR:  invalid overflow block number 2
 SELECT * FROM hash_bitmap_info('test_hash_a_idx', 3);
-ERROR:  page is not an overflow page
-DETAIL:  Expected 00000001, got 00000002.
+ERROR:  invalid overflow block number 3
 SELECT * FROM hash_bitmap_info('test_hash_a_idx', 4);
-ERROR:  page is not an overflow page
-DETAIL:  Expected 00000001, got 00000002.
+ERROR:  invalid overflow block number 4
 SELECT * FROM hash_bitmap_info('test_hash_a_idx', 5);
-ERROR:  page is not an overflow page
-DETAIL:  Expected 00000001, got 00000004.
+-[ RECORD 1 ]--
+bitmapblkno | 5
+bitmapbit   | 0
+bitstatus   | t
+
 SELECT magic, version, ntuples, bsize, bmsize, bmshift, maxbucket, highmask,
 lowmask, ovflpoint, firstfree, nmaps, procid, spares, mapp FROM
 hash_metapage_info(get_raw_page('test_hash_a_idx', 0));
diff --git a/contrib/pageinspect/hashfuncs.c b/contrib/pageinspect/hashfuncs.c
index 08663c1..a645e04 100644
--- a/contrib/pageinspect/hashfuncs.c
+++ b/contrib/pageinspect/hashfuncs.c
@@ -380,12 +380,11 @@ hash_bitmap_info(PG_FUNCTION_ARGS)
 	Oid			indexRelid = PG_GETARG_OID(0);
 	uint64		ovflblkno = PG_GETARG_INT64(1);
 	HashMetaPage metap;
-	Buffer		buf,
-				metabuf;
+	Buffer		metabuf,
+				mapbuf;
 	BlockNumber bitmapblkno;
-	Page		page;
+	Page		mappage;
 	bool		bit = false;
-	HashPageOpaque	opaque;
 	TupleDesc	tupleDesc;
 	Relation	indexRel;
 	uint32		ovflbitno;
@@ -395,6 +394,7 @@ hash_bitmap_info(PG_FUNCTION_ARGS)
 	int			j;
 	Datum		values[3];
 	bool		nulls[3];
+	uint32		*freep = NULL;
 
 	if (!superuser())
 		ereport(ERROR,
@@ -418,25 +418,6 @@ hash_bitmap_info(PG_FUNCTION_ARGS)
 				 errmsg("block number " UINT64_FORMAT " is out of range for relation \"%s\"",
 						ovflblkno, RelationGetRelationName(indexRel))));
 
-	buf = ReadBufferExtended(indexRel, MAIN_FORKNUM, (BlockNumber) ovflblkno,
-							 RBM_NORMAL, NULL);
-	LockBuffer(buf, BUFFER_LOCK_SHARE);
-	_hash_checkpage(indexRel, buf, LH_PAGE_TYPE);
-	page = BufferGetPage(buf);
-	opaque = (HashPageOpaque) PageGetSpecialPointer(page);
-
-	if (opaque->hasho_flag != LH_OVERFLOW_PAGE)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("page is not an overflow page"),
-				 errdetail("Expected %08x, got %08x.",
-							LH_OVERFLOW_PAGE, opaque->hasho_flag)));
-
-	if (BlockNumberIsValid(opaque->hasho_prevblkno))
-		bit = true;
-
-	UnlockReleaseBuffer(buf);
-
 	/* Read the metapage so we can determine which bitmap page to use */
 	metabuf = _hash_getbuf(indexRel, HASH_METAPAGE, HASH_READ, LH_META_PAGE);
 	metap = HashPageGetMeta(BufferGetPage(metabuf));
@@ -456,6 +437,14 @@ hash_bitmap_info(PG_FUNCTION_ARGS)
 
 	_hash_relbuf(indexRel, metabuf);
 
+	/* Check the status of bitmap bit for overflow page */
+	mapbuf = _hash_getbuf(indexRel, bitmapblkno, HASH_READ, LH_BITMAP_PAGE);
+	mappage = BufferGetPage(mapbuf);
+	freep = HashPageGetBitmap(mappage);
+
+	bit = ISSET(freep, bitmapbit) != 0;
+
+	_hash_relbuf(indexRel, mapbuf);
 	index_close(indexRel, AccessShareLock);
 
 	/* Build a tuple descriptor for our result type */
diff --git a/src/backend/access/hash/hashovfl.c b/src/backend/access/hash/hashovfl.c
index 753c8a6..9a13f6b 100644
--- a/src/backend/access/hash/hashovfl.c
+++ b/src/backend/access/hash/hashovfl.c
@@ -69,11 +69,20 @@ _hash_ovflblkno_to_bitno(HashMetaPage metap, BlockNumber ovflblkno)
 		if (ovflblkno <= (BlockNumber) (1 << i))
 			break;				/* oops */
 		bitnum = ovflblkno - (1 << i);
-		if (bitnum <= metap->hashm_spares[i])
+		/*
+		 * bitnum has to be greater than number of overflow
+		 * page added in previous split point. The overflow
+		 * page at this splitnum (i) if any should start from
+		 * ((2 ^ i) + metap->hashm_spares[i -1] + 1).
+		 */
+		if (bitnum > metap->hashm_spares[i -1] &&
+			bitnum <= metap->hashm_spares[i])
 			return bitnum - 1;	/* -1 to convert 1-based to 0-based */
 	}
 
-	elog(ERROR, "invalid overflow block number %u", ovflblkno);
+	ereport(ERROR,
+			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			 errmsg("invalid overflow block number %u", ovflblkno)));
 	return 0;					/* keep compiler quiet */
 }