Remove _hash_chgbufaccess().

This is basically for the same reasons I got rid of _hash_wrtbuf()
in commit 25216c98: it's not
convenient to have a function which encapsulates MarkBufferDirty(),
especially as we move towards having hash indexes be WAL-logged.

Patch by me, reviewed (but not entirely endorsed) by Amit Kapila.

src/backend/access/hash/hash.c

@@ -274,7 +274,7 @@ hashgettuple(IndexScanDesc scan, ScanDirection dir)
 	 * Reacquire the read lock here.
 	 */
 	if (BufferIsValid(so->hashso_curbuf))
-		_hash_chgbufaccess(rel, so->hashso_curbuf, HASH_NOLOCK, HASH_READ);
+		LockBuffer(so->hashso_curbuf, BUFFER_LOCK_SHARE);
 
 	/*
 	 * If we've already initialized this scan, we can just advance it in the
@@ -354,7 +354,7 @@ hashgettuple(IndexScanDesc scan, ScanDirection dir)
 
 	/* Release read lock on current buffer, but keep it pinned */
 	if (BufferIsValid(so->hashso_curbuf))
-		_hash_chgbufaccess(rel, so->hashso_curbuf, HASH_READ, HASH_NOLOCK);
+		LockBuffer(so->hashso_curbuf, BUFFER_LOCK_UNLOCK);
 
 	/* Return current heap TID on success */
 	scan->xs_ctup.t_self = so->hashso_heappos;
@@ -524,7 +524,7 @@ hashbulkdelete(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
 	orig_ntuples = metap->hashm_ntuples;
 	memcpy(&local_metapage, metap, sizeof(local_metapage));
 	/* release the lock, but keep pin */
-	_hash_chgbufaccess(rel, metabuf, HASH_READ, HASH_NOLOCK);
+	LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
 
 	/* Scan the buckets that we know exist */
 	cur_bucket = 0;
@@ -576,9 +576,9 @@ loop_top:
 			 * (and thus can't be further split), update our cached metapage
 			 * data.
 			 */
-			_hash_chgbufaccess(rel, metabuf, HASH_NOLOCK, HASH_READ);
+			LockBuffer(metabuf, BUFFER_LOCK_SHARE);
 			memcpy(&local_metapage, metap, sizeof(local_metapage));
-			_hash_chgbufaccess(rel, metabuf, HASH_READ, HASH_NOLOCK);
+			LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
 		}
 
 		bucket_buf = buf;
@@ -597,7 +597,7 @@ loop_top:
 	}
 
 	/* Write-lock metapage and check for split since we started */
-	_hash_chgbufaccess(rel, metabuf, HASH_NOLOCK, HASH_WRITE);
+	LockBuffer(metabuf, BUFFER_LOCK_EXCLUSIVE);
 	metap = HashPageGetMeta(BufferGetPage(metabuf));
 
 	if (cur_maxbucket != metap->hashm_maxbucket)
@@ -605,7 +605,7 @@ loop_top:
 		/* There's been a split, so process the additional bucket(s) */
 		cur_maxbucket = metap->hashm_maxbucket;
 		memcpy(&local_metapage, metap, sizeof(local_metapage));
-		_hash_chgbufaccess(rel, metabuf, HASH_READ, HASH_NOLOCK);
+		LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
 		goto loop_top;
 	}
 
@@ -821,7 +821,7 @@ hashbucketcleanup(Relation rel, Bucket cur_bucket, Buffer bucket_buf,
 		 * page
 		 */
 		if (retain_pin)
-			_hash_chgbufaccess(rel, buf, HASH_READ, HASH_NOLOCK);
+			LockBuffer(buf, BUFFER_LOCK_UNLOCK);
 		else
 			_hash_relbuf(rel, buf);
 
@@ -836,7 +836,7 @@ hashbucketcleanup(Relation rel, Bucket cur_bucket, Buffer bucket_buf,
 	if (buf != bucket_buf)
 	{
 		_hash_relbuf(rel, buf);
-		_hash_chgbufaccess(rel, bucket_buf, HASH_NOLOCK, HASH_WRITE);
+		LockBuffer(bucket_buf, BUFFER_LOCK_EXCLUSIVE);
 	}
 
 	/*
@@ -866,7 +866,7 @@ hashbucketcleanup(Relation rel, Bucket cur_bucket, Buffer bucket_buf,
 		_hash_squeezebucket(rel, cur_bucket, bucket_blkno, bucket_buf,
 							bstrategy);
 	else
-		_hash_chgbufaccess(rel, bucket_buf, HASH_READ, HASH_NOLOCK);
+		LockBuffer(bucket_buf, BUFFER_LOCK_UNLOCK);
 }
 
 void

src/backend/access/hash/hashinsert.c

@@ -104,7 +104,7 @@ restart_insert:
 		lowmask = metap->hashm_lowmask;
 
 		/* Release metapage lock, but keep pin. */
-		_hash_chgbufaccess(rel, metabuf, HASH_READ, HASH_NOLOCK);
+		LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
 
 		/*
 		 * If the previous iteration of this loop locked the primary page of
@@ -125,7 +125,7 @@ restart_insert:
 		 * Reacquire metapage lock and check that no bucket split has taken
 		 * place while we were awaiting the bucket lock.
 		 */
-		_hash_chgbufaccess(rel, metabuf, HASH_NOLOCK, HASH_READ);
+		LockBuffer(metabuf, BUFFER_LOCK_SHARE);
 		oldblkno = blkno;
 		retry = true;
 	}
@@ -149,7 +149,7 @@ restart_insert:
 	if (H_BUCKET_BEING_SPLIT(pageopaque) && IsBufferCleanupOK(buf))
 	{
 		/* release the lock on bucket buffer, before completing the split. */
-		_hash_chgbufaccess(rel, buf, HASH_READ, HASH_NOLOCK);
+		LockBuffer(buf, BUFFER_LOCK_UNLOCK);
 
 		_hash_finish_split(rel, metabuf, buf, pageopaque->hasho_bucket,
 						   maxbucket, highmask, lowmask);
@@ -180,7 +180,7 @@ restart_insert:
 			if (buf != bucket_buf)
 				_hash_relbuf(rel, buf);
 			else
-				_hash_chgbufaccess(rel, buf, HASH_READ, HASH_NOLOCK);
+				LockBuffer(buf, BUFFER_LOCK_UNLOCK);
 			buf = _hash_getbuf(rel, nextblkno, HASH_WRITE, LH_OVERFLOW_PAGE);
 			page = BufferGetPage(buf);
 		}
@@ -192,7 +192,7 @@ restart_insert:
 			 */
 
 			/* release our write lock without modifying buffer */
-			_hash_chgbufaccess(rel, buf, HASH_READ, HASH_NOLOCK);
+			LockBuffer(buf, BUFFER_LOCK_UNLOCK);
 
 			/* chain to a new overflow page */
 			buf = _hash_addovflpage(rel, metabuf, buf, (buf == bucket_buf) ? true : false);
@@ -223,7 +223,7 @@ restart_insert:
 	 * Write-lock the metapage so we can increment the tuple count. After
 	 * incrementing it, check to see if it's time for a split.
 	 */
-	_hash_chgbufaccess(rel, metabuf, HASH_NOLOCK, HASH_WRITE);
+	LockBuffer(metabuf, BUFFER_LOCK_EXCLUSIVE);
 
 	metap->hashm_ntuples += 1;
 
@@ -232,7 +232,8 @@ restart_insert:
 		(double) metap->hashm_ffactor * (metap->hashm_maxbucket + 1);
 
 	/* Write out the metapage and drop lock, but keep pin */
-	_hash_chgbufaccess(rel, metabuf, HASH_WRITE, HASH_NOLOCK);
+	MarkBufferDirty(metabuf);
+	LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
 
 	/* Attempt to split if a split is needed */
 	if (do_expand)

src/backend/access/hash/hashovfl.c

@@ -110,7 +110,7 @@ _hash_addovflpage(Relation rel, Buffer metabuf, Buffer buf, bool retain_pin)
 	 * Write-lock the tail page.  It is okay to hold two buffer locks here
 	 * since there cannot be anyone else contending for access to ovflbuf.
 	 */
-	_hash_chgbufaccess(rel, buf, HASH_NOLOCK, HASH_WRITE);
+	LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
 
 	/* probably redundant... */
 	_hash_checkpage(rel, buf, LH_BUCKET_PAGE | LH_OVERFLOW_PAGE);
@@ -129,7 +129,7 @@ _hash_addovflpage(Relation rel, Buffer metabuf, Buffer buf, bool retain_pin)
 
 		/* we assume we do not need to write the unmodified page */
 		if ((pageopaque->hasho_flag & LH_BUCKET_PAGE) && retain_pin)
-			_hash_chgbufaccess(rel, buf, HASH_READ, HASH_NOLOCK);
+			LockBuffer(buf, BUFFER_LOCK_UNLOCK);
 		else
 			_hash_relbuf(rel, buf);
 
@@ -151,7 +151,7 @@ _hash_addovflpage(Relation rel, Buffer metabuf, Buffer buf, bool retain_pin)
 	pageopaque->hasho_nextblkno = BufferGetBlockNumber(ovflbuf);
 	MarkBufferDirty(buf);
 	if ((pageopaque->hasho_flag & LH_BUCKET_PAGE) && retain_pin)
-		_hash_chgbufaccess(rel, buf, HASH_READ, HASH_NOLOCK);
+		LockBuffer(buf, BUFFER_LOCK_UNLOCK);
 	else
 		_hash_relbuf(rel, buf);
 
@@ -187,7 +187,7 @@ _hash_getovflpage(Relation rel, Buffer metabuf)
 				j;
 
 	/* Get exclusive lock on the meta page */
-	_hash_chgbufaccess(rel, metabuf, HASH_NOLOCK, HASH_WRITE);
+	LockBuffer(metabuf, BUFFER_LOCK_EXCLUSIVE);
 
 	_hash_checkpage(rel, metabuf, LH_META_PAGE);
 	metap = HashPageGetMeta(BufferGetPage(metabuf));
@@ -225,7 +225,7 @@ _hash_getovflpage(Relation rel, Buffer metabuf)
 			last_inpage = BMPGSZ_BIT(metap) - 1;
 
 		/* Release exclusive lock on metapage while reading bitmap page */
-		_hash_chgbufaccess(rel, metabuf, HASH_READ, HASH_NOLOCK);
+		LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
 
 		mapbuf = _hash_getbuf(rel, mapblkno, HASH_WRITE, LH_BITMAP_PAGE);
 		mappage = BufferGetPage(mapbuf);
@@ -244,7 +244,7 @@ _hash_getovflpage(Relation rel, Buffer metabuf)
 		bit = 0;
 
 		/* Reacquire exclusive lock on the meta page */
-		_hash_chgbufaccess(rel, metabuf, HASH_NOLOCK, HASH_WRITE);
+		LockBuffer(metabuf, BUFFER_LOCK_EXCLUSIVE);
 	}
 
 	/*
@@ -295,7 +295,8 @@ _hash_getovflpage(Relation rel, Buffer metabuf)
 		metap->hashm_firstfree = bit + 1;
 
 	/* Write updated metapage and release lock, but not pin */
-	_hash_chgbufaccess(rel, metabuf, HASH_WRITE, HASH_NOLOCK);
+	MarkBufferDirty(metabuf);
+	LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
 
 	return newbuf;
 
@@ -309,7 +310,7 @@ found:
 	_hash_relbuf(rel, mapbuf);
 
 	/* Reacquire exclusive lock on the meta page */
-	_hash_chgbufaccess(rel, metabuf, HASH_NOLOCK, HASH_WRITE);
+	LockBuffer(metabuf, BUFFER_LOCK_EXCLUSIVE);
 
 	/* convert bit to absolute bit number */
 	bit += (i << BMPG_SHIFT(metap));
@@ -326,12 +327,13 @@ found:
 		metap->hashm_firstfree = bit + 1;
 
 		/* Write updated metapage and release lock, but not pin */
-		_hash_chgbufaccess(rel, metabuf, HASH_WRITE, HASH_NOLOCK);
+		MarkBufferDirty(metabuf);
+		LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
 	}
 	else
 	{
 		/* We didn't change the metapage, so no need to write */
-		_hash_chgbufaccess(rel, metabuf, HASH_READ, HASH_NOLOCK);
+		LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
 	}
 
 	/* Fetch, init, and return the recycled page */
@@ -483,7 +485,7 @@ _hash_freeovflpage(Relation rel, Buffer ovflbuf, Buffer wbuf,
 	blkno = metap->hashm_mapp[bitmappage];
 
 	/* Release metapage lock while we access the bitmap page */
-	_hash_chgbufaccess(rel, metabuf, HASH_READ, HASH_NOLOCK);
+	LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
 
 	/* Clear the bitmap bit to indicate that this overflow page is free */
 	mapbuf = _hash_getbuf(rel, blkno, HASH_WRITE, LH_BITMAP_PAGE);
@@ -495,7 +497,7 @@ _hash_freeovflpage(Relation rel, Buffer ovflbuf, Buffer wbuf,
 	_hash_relbuf(rel, mapbuf);
 
 	/* Get write-lock on metapage to update firstfree */
-	_hash_chgbufaccess(rel, metabuf, HASH_NOLOCK, HASH_WRITE);
+	LockBuffer(metabuf, BUFFER_LOCK_EXCLUSIVE);
 
 	/* if this is now the first free page, update hashm_firstfree */
 	if (ovflbitno < metap->hashm_firstfree)
@@ -633,7 +635,7 @@ _hash_squeezebucket(Relation rel,
 	 */
 	if (!BlockNumberIsValid(wopaque->hasho_nextblkno))
 	{
-		_hash_chgbufaccess(rel, wbuf, HASH_READ, HASH_NOLOCK);
+		LockBuffer(wbuf, BUFFER_LOCK_UNLOCK);
 		return;
 	}
 
@@ -721,7 +723,7 @@ _hash_squeezebucket(Relation rel,
 				if (wbuf_dirty)
 					MarkBufferDirty(wbuf);
 				if (retain_pin)
-					_hash_chgbufaccess(rel, wbuf, HASH_READ, HASH_NOLOCK);
+					LockBuffer(wbuf, BUFFER_LOCK_UNLOCK);
 				else
 					_hash_relbuf(rel, wbuf);
 
@@ -784,7 +786,7 @@ _hash_squeezebucket(Relation rel,
 		{
 			/* retain the pin on primary bucket page till end of bucket scan */
 			if (wblkno == bucket_blkno)
-				_hash_chgbufaccess(rel, wbuf, HASH_READ, HASH_NOLOCK);
+				LockBuffer(wbuf, BUFFER_LOCK_UNLOCK);
 			else
 				_hash_relbuf(rel, wbuf);
 			return;

src/backend/access/hash/hashpage.c

@@ -289,32 +289,6 @@ _hash_dropscanbuf(Relation rel, HashScanOpaque so)
 	so->hashso_buc_split = false;
 }
 
-/*
- * _hash_chgbufaccess() -- Change the lock type on a buffer, without
- *			dropping our pin on it.
- *
- * from_access and to_access may be HASH_READ, HASH_WRITE, or HASH_NOLOCK,
- * the last indicating that no buffer-level lock is held or wanted.
- *
- * When from_access == HASH_WRITE, we assume the buffer is dirty and tell
- * bufmgr it must be written out.  If the caller wants to release a write
- * lock on a page that's not been modified, it's okay to pass from_access
- * as HASH_READ (a bit ugly, but handy in some places).
- */
-void
-_hash_chgbufaccess(Relation rel,
-				   Buffer buf,
-				   int from_access,
-				   int to_access)
-{
-	if (from_access == HASH_WRITE)
-		MarkBufferDirty(buf);
-	if (from_access != HASH_NOLOCK)
-		LockBuffer(buf, BUFFER_LOCK_UNLOCK);
-	if (to_access != HASH_NOLOCK)
-		LockBuffer(buf, to_access);
-}
-
 
 /*
  *	_hash_metapinit() -- Initialize the metadata page of a hash index,
@@ -446,7 +420,8 @@ _hash_metapinit(Relation rel, double num_tuples, ForkNumber forkNum)
 	 * won't accomplish anything.  It's a bad idea to hold buffer locks for
 	 * long intervals in any case, since that can block the bgwriter.
 	 */
-	_hash_chgbufaccess(rel, metabuf, HASH_WRITE, HASH_NOLOCK);
+	MarkBufferDirty(metabuf);
+	LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
 
 	/*
 	 * Initialize the first N buckets
@@ -469,7 +444,7 @@ _hash_metapinit(Relation rel, double num_tuples, ForkNumber forkNum)
 	}
 
 	/* Now reacquire buffer lock on metapage */
-	_hash_chgbufaccess(rel, metabuf, HASH_NOLOCK, HASH_WRITE);
+	LockBuffer(metabuf, BUFFER_LOCK_EXCLUSIVE);
 
 	/*
 	 * Initialize first bitmap page
@@ -528,7 +503,7 @@ restart_expand:
 	 * Write-lock the meta page.  It used to be necessary to acquire a
 	 * heavyweight lock to begin a split, but that is no longer required.
 	 */
-	_hash_chgbufaccess(rel, metabuf, HASH_NOLOCK, HASH_WRITE);
+	LockBuffer(metabuf, BUFFER_LOCK_EXCLUSIVE);
 
 	_hash_checkpage(rel, metabuf, LH_META_PAGE);
 	metap = HashPageGetMeta(BufferGetPage(metabuf));
@@ -609,8 +584,8 @@ restart_expand:
 		 * Release the lock on metapage and old_bucket, before completing the
 		 * split.
 		 */
-		_hash_chgbufaccess(rel, metabuf, HASH_READ, HASH_NOLOCK);
-		_hash_chgbufaccess(rel, buf_oblkno, HASH_READ, HASH_NOLOCK);
+		LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
+		LockBuffer(buf_oblkno, BUFFER_LOCK_UNLOCK);
 
 		_hash_finish_split(rel, metabuf, buf_oblkno, old_bucket, maxbucket,
 						   highmask, lowmask);
@@ -646,7 +621,7 @@ restart_expand:
 		lowmask = metap->hashm_lowmask;
 
 		/* Release the metapage lock. */
-		_hash_chgbufaccess(rel, metabuf, HASH_READ, HASH_NOLOCK);
+		LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
 
 		hashbucketcleanup(rel, old_bucket, buf_oblkno, start_oblkno, NULL,
 						  maxbucket, highmask, lowmask, NULL, NULL, true,
@@ -753,7 +728,8 @@ restart_expand:
 	lowmask = metap->hashm_lowmask;
 
 	/* Write out the metapage and drop lock, but keep pin */
-	_hash_chgbufaccess(rel, metabuf, HASH_WRITE, HASH_NOLOCK);
+	MarkBufferDirty(metabuf);
+	LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
 
 	/* Relocate records to the new bucket */
 	_hash_splitbucket(rel, metabuf,
@@ -767,7 +743,7 @@ restart_expand:
 fail:
 
 	/* We didn't write the metapage, so just drop lock */
-	_hash_chgbufaccess(rel, metabuf, HASH_READ, HASH_NOLOCK);
+	LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
 }
 
 
@@ -1001,7 +977,8 @@ _hash_splitbucket_guts(Relation rel,
 				if (PageGetFreeSpace(npage) < itemsz)
 				{
 					/* write out nbuf and drop lock, but keep pin */
-					_hash_chgbufaccess(rel, nbuf, HASH_WRITE, HASH_NOLOCK);
+					MarkBufferDirty(nbuf);
+					LockBuffer(nbuf, BUFFER_LOCK_UNLOCK);
 					/* chain to a new overflow page */
 					nbuf = _hash_addovflpage(rel, metabuf, nbuf, (nbuf == bucket_nbuf) ? true : false);
 					npage = BufferGetPage(nbuf);
@@ -1033,7 +1010,7 @@ _hash_splitbucket_guts(Relation rel,
 
 		/* retain the pin on the old primary bucket */
 		if (obuf == bucket_obuf)
-			_hash_chgbufaccess(rel, obuf, HASH_READ, HASH_NOLOCK);
+			LockBuffer(obuf, BUFFER_LOCK_UNLOCK);
 		else
 			_hash_relbuf(rel, obuf);
 
@@ -1056,18 +1033,21 @@ _hash_splitbucket_guts(Relation rel,
 	 * bucket and then the new bucket.
 	 */
 	if (nbuf == bucket_nbuf)
-		_hash_chgbufaccess(rel, bucket_nbuf, HASH_WRITE, HASH_NOLOCK);
+	{
+		MarkBufferDirty(bucket_nbuf);
+		LockBuffer(bucket_nbuf, BUFFER_LOCK_UNLOCK);
+	}
 	else
 	{
 		MarkBufferDirty(nbuf);
 		_hash_relbuf(rel, nbuf);
 	}
 
-	_hash_chgbufaccess(rel, bucket_obuf, HASH_NOLOCK, HASH_WRITE);
+	LockBuffer(bucket_obuf, BUFFER_LOCK_EXCLUSIVE);
 	opage = BufferGetPage(bucket_obuf);
 	oopaque = (HashPageOpaque) PageGetSpecialPointer(opage);
 
-	_hash_chgbufaccess(rel, bucket_nbuf, HASH_NOLOCK, HASH_WRITE);
+	LockBuffer(bucket_nbuf, BUFFER_LOCK_EXCLUSIVE);
 	npage = BufferGetPage(bucket_nbuf);
 	nopaque = (HashPageOpaque) PageGetSpecialPointer(npage);
 
@@ -1172,7 +1152,7 @@ _hash_finish_split(Relation rel, Buffer metabuf, Buffer obuf, Bucket obucket,
 		 * retain the pin on primary bucket.
 		 */
 		if (nbuf == bucket_nbuf)
-			_hash_chgbufaccess(rel, nbuf, HASH_READ, HASH_NOLOCK);
+			LockBuffer(nbuf, BUFFER_LOCK_UNLOCK);
 		else
 			_hash_relbuf(rel, nbuf);
 
@@ -1194,7 +1174,7 @@ _hash_finish_split(Relation rel, Buffer metabuf, Buffer obuf, Bucket obucket,
 	}
 	if (!ConditionalLockBufferForCleanup(bucket_nbuf))
 	{
-		_hash_chgbufaccess(rel, obuf, HASH_READ, HASH_NOLOCK);
+		LockBuffer(obuf, BUFFER_LOCK_UNLOCK);
 		hash_destroy(tidhtab);
 		return;
 	}
@@ -1208,6 +1188,6 @@ _hash_finish_split(Relation rel, Buffer metabuf, Buffer obuf, Bucket obucket,
 						   maxbucket, highmask, lowmask);
 
 	_hash_relbuf(rel, bucket_nbuf);
-	_hash_chgbufaccess(rel, obuf, HASH_READ, HASH_NOLOCK);
+	LockBuffer(obuf, BUFFER_LOCK_UNLOCK);
 	hash_destroy(tidhtab);
 }

src/backend/access/hash/hashsearch.c

@@ -83,7 +83,7 @@ _hash_readnext(IndexScanDesc scan,
 	 * comments in _hash_first to know the reason of retaining pin.
 	 */
 	if (*bufp == so->hashso_bucket_buf || *bufp == so->hashso_split_bucket_buf)
-		_hash_chgbufaccess(rel, *bufp, HASH_READ, HASH_NOLOCK);
+		LockBuffer(*bufp, BUFFER_LOCK_UNLOCK);
 	else
 		_hash_relbuf(rel, *bufp);
 
@@ -109,7 +109,7 @@ _hash_readnext(IndexScanDesc scan,
 		 */
 		Assert(BufferIsValid(*bufp));
 
-		_hash_chgbufaccess(rel, *bufp, HASH_NOLOCK, HASH_READ);
+		LockBuffer(*bufp, BUFFER_LOCK_SHARE);
 
 		/*
 		 * setting hashso_buc_split to true indicates that we are scanning
@@ -147,7 +147,7 @@ _hash_readprev(IndexScanDesc scan,
 	 * comments in _hash_first to know the reason of retaining pin.
 	 */
 	if (*bufp == so->hashso_bucket_buf || *bufp == so->hashso_split_bucket_buf)
-		_hash_chgbufaccess(rel, *bufp, HASH_READ, HASH_NOLOCK);
+		LockBuffer(*bufp, BUFFER_LOCK_UNLOCK);
 	else
 		_hash_relbuf(rel, *bufp);
 
@@ -182,7 +182,7 @@ _hash_readprev(IndexScanDesc scan,
 		 */
 		Assert(BufferIsValid(*bufp));
 
-		_hash_chgbufaccess(rel, *bufp, HASH_NOLOCK, HASH_READ);
+		LockBuffer(*bufp, BUFFER_LOCK_SHARE);
 		*pagep = BufferGetPage(*bufp);
 		*opaquep = (HashPageOpaque) PageGetSpecialPointer(*pagep);
 
@@ -298,7 +298,7 @@ _hash_first(IndexScanDesc scan, ScanDirection dir)
 		blkno = BUCKET_TO_BLKNO(metap, bucket);
 
 		/* Release metapage lock, but keep pin. */
-		_hash_chgbufaccess(rel, metabuf, HASH_READ, HASH_NOLOCK);
+		LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
 
 		/*
 		 * If the previous iteration of this loop locked what is still the
@@ -319,7 +319,7 @@ _hash_first(IndexScanDesc scan, ScanDirection dir)
 		 * Reacquire metapage lock and check that no bucket split has taken
 		 * place while we were awaiting the bucket lock.
 		 */
-		_hash_chgbufaccess(rel, metabuf, HASH_NOLOCK, HASH_READ);
+		LockBuffer(metabuf, BUFFER_LOCK_SHARE);
 		oldblkno = blkno;
 		retry = true;
 	}
@@ -359,7 +359,7 @@ _hash_first(IndexScanDesc scan, ScanDirection dir)
 		 * release the lock on new bucket and re-acquire it after acquiring
 		 * the lock on old bucket.
 		 */
-		_hash_chgbufaccess(rel, buf, HASH_READ, HASH_NOLOCK);
+		LockBuffer(buf, BUFFER_LOCK_UNLOCK);
 
 		old_buf = _hash_getbuf(rel, old_blkno, HASH_READ, LH_BUCKET_PAGE);
 
@@ -368,9 +368,9 @@ _hash_first(IndexScanDesc scan, ScanDirection dir)
 		 * scanning.
 		 */
 		so->hashso_split_bucket_buf = old_buf;
-		_hash_chgbufaccess(rel, old_buf, HASH_READ, HASH_NOLOCK);
+		LockBuffer(old_buf, BUFFER_LOCK_UNLOCK);
 
-		_hash_chgbufaccess(rel, buf, HASH_NOLOCK, HASH_READ);
+		LockBuffer(buf, BUFFER_LOCK_SHARE);
 		page = BufferGetPage(buf);
 		opaque = (HashPageOpaque) PageGetSpecialPointer(page);
 		Assert(opaque->hasho_bucket == bucket);

src/include/access/hash.h

@@ -336,8 +336,6 @@ extern Buffer _hash_getbuf_with_strategy(Relation rel, BlockNumber blkno,
 extern void _hash_relbuf(Relation rel, Buffer buf);
 extern void _hash_dropbuf(Relation rel, Buffer buf);
 extern void _hash_dropscanbuf(Relation rel, HashScanOpaque so);
-extern void _hash_chgbufaccess(Relation rel, Buffer buf, int from_access,
-				   int to_access);
 extern uint32 _hash_metapinit(Relation rel, double num_tuples,
 				ForkNumber forkNum);
 extern void _hash_pageinit(Page page, Size size);