fix_XLogFileNameP_v2.patch

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 5f0ee50092..fb1262a175 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -2499,14 +2499,21 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible)
 				pgstat_report_wait_end();
 				if (written <= 0)
 				{
+					char xlogfname[MAXFNAMELEN];
+					int	save_errno;
+
 					if (errno == EINTR)
 						continue;
+
+					save_errno = errno;
+					XLogFileName(xlogfname, ThisTimeLineID, openLogSegNo,
+								 wal_segment_size);
+					errno = save_errno;
 					ereport(PANIC,
 							(errcode_for_file_access(),
 							 errmsg("could not write to log file %s "
 									"at offset %u, length %zu: %m",
-									XLogFileNameP(ThisTimeLineID, openLogSegNo),
-									startoffset, nleft)));
+									xlogfname, startoffset, nleft)));
 				}
 				nleft -= written;
 				from += written;
@@ -3792,10 +3799,17 @@ XLogFileClose(void)
 #endif
 
 	if (close(openLogFile) != 0)
+	{
+		char xlogfname[MAXFNAMELEN];
+		int	save_errno = errno;
+
+		XLogFileName(xlogfname, ThisTimeLineID, openLogSegNo, wal_segment_size);
+		errno = save_errno;
 		ereport(PANIC,
 				(errcode_for_file_access(),
-				 errmsg("could not close file \"%s\": %m",
-						XLogFileNameP(ThisTimeLineID, openLogSegNo))));
+				 errmsg("could not close file \"%s\": %m", xlogfname)));
+	}
+
 	openLogFile = -1;
 }
 
@@ -5510,10 +5524,17 @@ exitArchiveRecovery(TimeLineID endTLI, XLogRecPtr endOfLog)
 		fd = XLogFileInit(startLogSegNo, &use_existent, true);
 
 		if (close(fd) != 0)
+		{
+			char xlogfname[MAXFNAMELEN];
+			int	save_errno = errno;
+
+			XLogFileName(xlogfname, ThisTimeLineID, openLogSegNo,
+						 wal_segment_size);
+			errno = save_errno;
 			ereport(ERROR,
 					(errcode_for_file_access(),
-					 errmsg("could not close file \"%s\": %m",
-							XLogFileNameP(ThisTimeLineID, startLogSegNo))));
+					 errmsg("could not close file \"%s\": %m", xlogfname)));
+		}
 	}
 
 	/*
@@ -10079,10 +10100,18 @@ assign_xlog_sync_method(int new_sync_method, void *extra)
 		{
 			pgstat_report_wait_start(WAIT_EVENT_WAL_SYNC_METHOD_ASSIGN);
 			if (pg_fsync(openLogFile) != 0)
+			{
+				char xlogfname[MAXFNAMELEN];
+				int	save_errno;
+
+				save_errno = errno;
+				XLogFileName(xlogfname, ThisTimeLineID, openLogSegNo,
+							 wal_segment_size);
 				ereport(PANIC,
 						(errcode_for_file_access(),
-						 errmsg("could not fsync file \"%s\": %m",
-								XLogFileNameP(ThisTimeLineID, openLogSegNo))));
+						 errmsg("could not fsync file \"%s\": %m", xlogfname)));
+			}
+
 			pgstat_report_wait_end();
 			if (get_sync_bit(sync_method) != get_sync_bit(new_sync_method))
 				XLogFileClose();
@@ -10100,32 +10129,25 @@ assign_xlog_sync_method(int new_sync_method, void *extra)
 void
 issue_xlog_fsync(int fd, XLogSegNo segno)
 {
+	char *msg = NULL;
+
 	pgstat_report_wait_start(WAIT_EVENT_WAL_SYNC);
 	switch (sync_method)
 	{
 		case SYNC_METHOD_FSYNC:
 			if (pg_fsync_no_writethrough(fd) != 0)
-				ereport(PANIC,
-						(errcode_for_file_access(),
-						 errmsg("could not fsync file \"%s\": %m",
-								XLogFileNameP(ThisTimeLineID, segno))));
+				msg = _("could not fsync file \"%s\": %m");
 			break;
 #ifdef HAVE_FSYNC_WRITETHROUGH
 		case SYNC_METHOD_FSYNC_WRITETHROUGH:
 			if (pg_fsync_writethrough(fd) != 0)
-				ereport(PANIC,
-						(errcode_for_file_access(),
-						 errmsg("could not fsync write-through file \"%s\": %m",
-								XLogFileNameP(ThisTimeLineID, segno))));
+				msg = _("could not fsync write-through file \"%s\": %m");
 			break;
 #endif
 #ifdef HAVE_FDATASYNC
 		case SYNC_METHOD_FDATASYNC:
 			if (pg_fdatasync(fd) != 0)
-				ereport(PANIC,
-						(errcode_for_file_access(),
-						 errmsg("could not fdatasync file \"%s\": %m",
-								XLogFileNameP(ThisTimeLineID, segno))));
+				msg = _("could not fdatasync file \"%s\": %m");
 			break;
 #endif
 		case SYNC_METHOD_OPEN:
@@ -10136,19 +10158,22 @@ issue_xlog_fsync(int fd, XLogSegNo segno)
 			elog(PANIC, "unrecognized wal_sync_method: %d", sync_method);
 			break;
 	}
-	pgstat_report_wait_end();
-}
 
-/*
- * Return the filename of given log segment, as a palloc'd string.
- */
-char *
-XLogFileNameP(TimeLineID tli, XLogSegNo segno)
-{
-	char	   *result = palloc(MAXFNAMELEN);
+	/* PANIC if failed to fsync */
+	if (msg)
+	{
+		char	xlogfname[MAXFNAMELEN];
+		int		save_errno = errno;
 
-	XLogFileName(result, tli, segno, wal_segment_size);
-	return result;
+		XLogFileName(xlogfname, ThisTimeLineID, openLogSegNo,
+					 wal_segment_size);
+		errno = save_errno;
+		ereport(PANIC,
+				(errcode_for_file_access(),
+				 errmsg(msg, xlogfname)));
+	}
+
+	pgstat_report_wait_end();
 }
 
 /*
diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index 446760ed6e..ca73ef5131 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -944,7 +944,9 @@ void
 WALReadRaiseError(WALReadError *errinfo)
 {
 	WALOpenSegment *seg = &errinfo->wre_seg;
-	char	   *fname = XLogFileNameP(seg->ws_tli, seg->ws_segno);
+	char	   fname[MAXFNAMELEN];
+
+	XLogFileName(fname, seg->ws_tli, seg->ws_segno, wal_segment_size);
 
 	if (errinfo->wre_read < 0)
 	{
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 72acb10767..9214ca6526 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -576,17 +576,17 @@ WalReceiverMain(void)
 			char		xlogfname[MAXFNAMELEN];
 
 			XLogWalRcvFlush(false);
+			XLogFileName(xlogfname, recvFileTLI, recvSegNo, wal_segment_size);
 			if (close(recvFile) != 0)
 				ereport(PANIC,
 						(errcode_for_file_access(),
 						 errmsg("could not close log segment %s: %m",
-								XLogFileNameP(recvFileTLI, recvSegNo))));
+								xlogfname)));
 
 			/*
 			 * Create .done file forcibly to prevent the streamed segment from
 			 * being archived later.
 			 */
-			XLogFileName(xlogfname, recvFileTLI, recvSegNo, wal_segment_size);
 			if (XLogArchiveMode != ARCHIVE_MODE_ALWAYS)
 				XLogArchiveForceDone(xlogfname);
 			else
@@ -900,6 +900,8 @@ XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
 
 				XLogWalRcvFlush(false);
 
+				XLogFileName(xlogfname, recvFileTLI, recvSegNo, wal_segment_size);
+
 				/*
 				 * XLOG segment files will be re-read by recovery in startup
 				 * process soon, so we don't advise the OS to release cache
@@ -909,13 +911,12 @@ XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
 					ereport(PANIC,
 							(errcode_for_file_access(),
 							 errmsg("could not close log segment %s: %m",
-									XLogFileNameP(recvFileTLI, recvSegNo))));
+									xlogfname)));
 
 				/*
 				 * Create .done file forcibly to prevent the streamed segment
 				 * from being archived later.
 				 */
-				XLogFileName(xlogfname, recvFileTLI, recvSegNo, wal_segment_size);
 				if (XLogArchiveMode != ARCHIVE_MODE_ALWAYS)
 					XLogArchiveForceDone(xlogfname);
 				else
@@ -943,11 +944,18 @@ XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
 		if (recvOff != startoff)
 		{
 			if (lseek(recvFile, (off_t) startoff, SEEK_SET) < 0)
+			{
+				char xlogfname[MAXFNAMELEN];
+				int	save_errno = errno;
+
+				XLogFileName(xlogfname, recvFileTLI, recvSegNo, wal_segment_size);
+				errno = save_errno;
 				ereport(PANIC,
 						(errcode_for_file_access(),
 						 errmsg("could not seek in log segment %s to offset %u: %m",
-								XLogFileNameP(recvFileTLI, recvSegNo),
-								startoff)));
+								xlogfname, startoff)));
+			}
+
 			recvOff = startoff;
 		}
 
@@ -957,15 +965,21 @@ XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
 		byteswritten = write(recvFile, buf, segbytes);
 		if (byteswritten <= 0)
 		{
+			char xlogfname[MAXFNAMELEN];
+			int	save_errno;
+
 			/* if write didn't set errno, assume no disk space */
 			if (errno == 0)
 				errno = ENOSPC;
+
+			save_errno = errno;
+			XLogFileName(xlogfname, recvFileTLI, recvSegNo, wal_segment_size);
+			errno = save_errno;
 			ereport(PANIC,
 					(errcode_for_file_access(),
 					 errmsg("could not write to log segment %s "
 							"at offset %u, length %lu: %m",
-							XLogFileNameP(recvFileTLI, recvSegNo),
-							recvOff, (unsigned long) segbytes)));
+							xlogfname, recvOff, (unsigned long) segbytes)));
 		}
 
 		/* Update state for write */
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 8bafa65e50..5fcdec5f21 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -2434,10 +2434,17 @@ WalSndSegmentOpen(XLogSegNo nextSegNo, WALSegmentContext *segcxt,
 	 * too old WAL segment that has already been removed or recycled.
 	 */
 	if (errno == ENOENT)
+	{
+		char xlogfname[MAXFNAMELEN];
+		int	save_errno = errno;
+
+		XLogFileName(xlogfname, *tli_p, nextSegNo, wal_segment_size);
+		errno = save_errno;
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("requested WAL segment %s has already been removed",
-						XLogFileNameP(*tli_p, nextSegNo))));
+						xlogfname)));
+	}
 	else
 		ereport(ERROR,
 				(errcode_for_file_access(),
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index d519252aad..9b588c87a5 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -288,7 +288,6 @@ extern bool RecoveryIsPaused(void);
 extern void SetRecoveryPause(bool recoveryPause);
 extern TimestampTz GetLatestXTime(void);
 extern TimestampTz GetCurrentChunkReplayStartTime(void);
-extern char *XLogFileNameP(TimeLineID tli, XLogSegNo segno);
 
 extern void UpdateControlFile(void);
 extern uint64 GetSystemIdentifier(void);
diff --git a/src/include/access/xlog_internal.h b/src/include/access/xlog_internal.h
index e7e10beb4c..ba8e0f8d9f 100644
--- a/src/include/access/xlog_internal.h
+++ b/src/include/access/xlog_internal.h
@@ -152,6 +152,12 @@ typedef XLogLongPageHeaderData *XLogLongPageHeader;
 /* Length of XLog file name */
 #define XLOG_FNAME_LEN	   24
 
+/*
+ * Write xlog file name to fname. We used to have a helper function that returns
+ * the xlog file name as a palloc'd string. But we will never need such a function
+ * because it cannot be used during the critical section and it is hard to fix so
+ * that it is never misused.
+ */
 #define XLogFileName(fname, tli, logSegNo, wal_segsz_bytes)	\
 	snprintf(fname, MAXFNAMELEN, "%08X%08X%08X", tli,		\
 			 (uint32) ((logSegNo) / XLogSegmentsPerXLogId(wal_segsz_bytes)), \