1 files changed, 27 insertions, 17 deletions

diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index da0e45bfcc6..cf04081c19e 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -287,9 +287,13 @@ XLogReadBufferForRedo(XLogRecPtr lsn, XLogRecord *record, int block_index,
  * XLogReadBufferForRedoExtended
  *		Like XLogReadBufferForRedo, but with extra options.
  *
- * If mode is RBM_ZERO or RBM_ZERO_ON_ERROR, if the page doesn't exist, the
- * relation is extended with all-zeroes pages up to the referenced block
- * number.  In RBM_ZERO mode, the return value is always BLK_NEEDS_REDO.
+ * In RBM_ZERO_* modes, if the page doesn't exist, the relation is extended
+ * with all-zeroes pages up to the referenced block number.  In
+ * RBM_ZERO_AND_LOCK and RBM_ZERO_AND_CLEANUP_LOCK modes, the return value
+ * is always BLK_NEEDS_REDO.
+ *
+ * (The RBM_ZERO_AND_CLEANUP_LOCK mode is redundant with the get_cleanup_lock
+ * parameter. Do not use an inconsistent combination!)
  *
  * If 'get_cleanup_lock' is true, a "cleanup lock" is acquired on the buffer
  * using LockBufferForCleanup(), instead of a regular exclusive lock.
@@ -312,10 +316,13 @@ XLogReadBufferForRedoExtended(XLogRecPtr lsn, XLogRecord *record,
 		*buf = XLogReadBufferExtended(rnode, forkno, blkno, mode);
 		if (BufferIsValid(*buf))
 		{
-			if (get_cleanup_lock)
-				LockBufferForCleanup(*buf);
-			else
-				LockBuffer(*buf, BUFFER_LOCK_EXCLUSIVE);
+			if (mode != RBM_ZERO_AND_LOCK && mode != RBM_ZERO_AND_CLEANUP_LOCK)
+			{
+				if (get_cleanup_lock)
+					LockBufferForCleanup(*buf);
+				else
+					LockBuffer(*buf, BUFFER_LOCK_EXCLUSIVE);
+			}
 			if (lsn <= PageGetLSN(BufferGetPage(*buf)))
 				return BLK_DONE;
 			else
@@ -341,7 +348,8 @@ XLogReadBufferForRedoExtended(XLogRecPtr lsn, XLogRecord *record,
  * The returned buffer is exclusively-locked.
  *
  * For historical reasons, instead of a ReadBufferMode argument, this only
- * supports RBM_ZERO (init == true) and RBM_NORMAL (init == false) modes.
+ * supports RBM_ZERO_AND_LOCK (init == true) and RBM_NORMAL (init == false)
+ * modes.
  */
 Buffer
 XLogReadBuffer(RelFileNode rnode, BlockNumber blkno, bool init)
@@ -349,8 +357,8 @@ XLogReadBuffer(RelFileNode rnode, BlockNumber blkno, bool init)
 	Buffer		buf;
 
 	buf = XLogReadBufferExtended(rnode, MAIN_FORKNUM, blkno,
-								 init ? RBM_ZERO : RBM_NORMAL);
-	if (BufferIsValid(buf))
+								 init ? RBM_ZERO_AND_LOCK : RBM_NORMAL);
+	if (BufferIsValid(buf) && !init)
 		LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
 
 	return buf;
@@ -369,8 +377,8 @@ XLogReadBuffer(RelFileNode rnode, BlockNumber blkno, bool init)
  * dropped or truncated. If we don't see evidence of that later in the WAL
  * sequence, we'll complain at the end of WAL replay.)
  *
- * In RBM_ZERO and RBM_ZERO_ON_ERROR modes, if the page doesn't exist, the
- * relation is extended with all-zeroes pages up to the given block number.
+ * In RBM_ZERO_* modes, if the page doesn't exist, the relation is extended
+ * with all-zeroes pages up to the given block number.
  *
  * In RBM_NORMAL_NO_LOG mode, we return InvalidBuffer if the page doesn't
  * exist, and we don't check for all-zeroes.  Thus, no log entry is made
@@ -424,7 +432,11 @@ XLogReadBufferExtended(RelFileNode rnode, ForkNumber forknum,
 		do
 		{
 			if (buffer != InvalidBuffer)
+			{
+				if (mode == RBM_ZERO_AND_LOCK || mode == RBM_ZERO_AND_CLEANUP_LOCK)
+					LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
 				ReleaseBuffer(buffer);
+			}
 			buffer = ReadBufferWithoutRelcache(rnode, forknum,
 											   P_NEW, mode, NULL);
 		}
@@ -432,6 +444,8 @@ XLogReadBufferExtended(RelFileNode rnode, ForkNumber forknum,
 		/* Handle the corner case that P_NEW returns non-consecutive pages */
 		if (BufferGetBlockNumber(buffer) != blkno)
 		{
+			if (mode == RBM_ZERO_AND_LOCK || mode == RBM_ZERO_AND_CLEANUP_LOCK)
+				LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
 			ReleaseBuffer(buffer);
 			buffer = ReadBufferWithoutRelcache(rnode, forknum, blkno,
 											   mode, NULL);
@@ -537,12 +551,8 @@ RestoreBackupBlockContents(XLogRecPtr lsn, BkpBlock bkpb, char *blk,
 	Page		page;
 
 	buffer = XLogReadBufferExtended(bkpb.node, bkpb.fork, bkpb.block,
-									RBM_ZERO);
+									get_cleanup_lock ? RBM_ZERO_AND_CLEANUP_LOCK : RBM_ZERO_AND_LOCK);
 	Assert(BufferIsValid(buffer));
-	if (get_cleanup_lock)
-		LockBufferForCleanup(buffer);
-	else
-		LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
 
 	page = (Page) BufferGetPage(buffer);