remove-exclusive-backup-v2.patch

From 035153589f47047d38cbb2ffef89d7f1f67e85cc Mon Sep 17 00:00:00 2001
From: David Steele <david@pgmasters.net>
Date: Tue, 30 Jun 2020 17:23:51 -0400
Subject: [PATCH] Remove Deprecated Exclusive Backup Mode.

Remove the exclusive backup mode which has been deprecated since 
PostgreSQL 9.6.

---
 doc/src/sgml/backup.sgml                      | 150 +-----
 doc/src/sgml/func.sgml                        |  82 +--
 src/backend/access/transam/xlog.c             | 476 ++----------------
 src/backend/access/transam/xlogfuncs.c        | 245 ++-------
 src/backend/catalog/system_views.sql          |   3 +-
 src/backend/postmaster/postmaster.c           |  46 +-
 src/backend/replication/basebackup.c          |   6 +-
 src/backend/utils/init/postinit.c             |   2 +-
 src/bin/pg_basebackup/t/010_pg_basebackup.pl  |   4 +
 src/bin/pg_rewind/filemap.c                   |   6 +-
 src/include/access/xlog.h                     |   3 +-
 src/include/catalog/pg_proc.dat               |  12 +-
 src/include/libpq/libpq-be.h                  |   3 +-
 src/include/miscadmin.h                       |   4 -
 src/test/perl/PostgresNode.pm                 |  56 +--
 .../t/010_logical_decoding_timelines.pl       |   4 +-
 16 files changed, 128 insertions(+), 974 deletions(-)

diff --git a/doc/src/sgml/backup.sgml b/doc/src/sgml/backup.sgml
index bdc9026c62..c544d79a1b 100644
--- a/doc/src/sgml/backup.sgml
+++ b/doc/src/sgml/backup.sgml
@@ -819,16 +819,9 @@ test ! -f /mnt/server/archivedir/00000001000000A900000065 &amp;&amp; cp pg_wal/0
     sequence, and that the success of a step is verified before
     proceeding to the next step.
    </para>
-   <para>
-    Low level base backups can be made in a non-exclusive or an exclusive
-    way. The non-exclusive method is recommended and the exclusive one is
-    deprecated and will eventually be removed.
-   </para>
 
-   <sect3 id="backup-lowlevel-base-backup-nonexclusive">
-    <title>Making a Non-Exclusive Low-Level Backup</title>
     <para>
-     A non-exclusive low level backup is one that allows other
+     A low level backup allows other
      concurrent backups to be running (both those started using
      the same backup API and those started using
      <xref linkend="app-pgbasebackup"/>).
@@ -868,8 +861,9 @@ SELECT pg_start_backup('label', false, false);
     </para>
 
     <para>
-     The third parameter being <literal>false</literal> tells
-     <function>pg_start_backup</function> to initiate a non-exclusive base backup.
+     The third parameter must always be set to <literal>false</literal>. The
+     default of <literal>true</literal> requests an exclusive backup, which is
+     no longer supported.
     </para>
    </listitem>
    <listitem>
@@ -946,142 +940,6 @@ SELECT * FROM pg_stop_backup(false, true);
    </listitem>
   </orderedlist>
     </para>
-   </sect3>
-   <sect3 id="backup-lowlevel-base-backup-exclusive">
-    <title>Making an Exclusive Low-Level Backup</title>
-
-    <note>
-     <para>
-      The exclusive backup method is deprecated and should be avoided.
-      Prior to <productname>PostgreSQL</productname> 9.6, this was the only
-      low-level method available, but it is now recommended that all users
-      upgrade their scripts to use non-exclusive backups.
-     </para>
-    </note>
-
-    <para>
-     The process for an exclusive backup is mostly the same as for a
-     non-exclusive one, but it differs in a few key steps. This type of
-     backup can only be taken on a primary and does not allow concurrent
-     backups.  Moreover, because it creates a backup label file, as
-     described below, it can block automatic restart of the master server
-     after a crash.  On the other hand, the erroneous removal of this
-     file from a backup or standby is a common mistake, which can result
-     in serious data corruption.  If it is necessary to use this method,
-     the following steps may be used.
-    </para>
-    <para>
-  <orderedlist>
-   <listitem>
-    <para>
-     Ensure that WAL archiving is enabled and working.
-    </para>
-   </listitem>
-   <listitem>
-    <para>
-     Connect to the server (it does not matter which database) as a user with
-     rights to run pg_start_backup (superuser, or a user who has been granted
-     EXECUTE on the function) and issue the command:
-<programlisting>
-SELECT pg_start_backup('label');
-</programlisting>
-     where <literal>label</literal> is any string you want to use to uniquely
-     identify this backup operation.
-     <function>pg_start_backup</function> creates a <firstterm>backup label</firstterm> file,
-     called <filename>backup_label</filename>, in the cluster directory with
-     information about your backup, including the start time and label string.
-     The function also creates a <firstterm>tablespace map</firstterm> file,
-     called <filename>tablespace_map</filename>, in the cluster directory with
-     information about tablespace symbolic links in <filename>pg_tblspc/</filename> if
-     one or more such link is present.  Both files are critical to the
-     integrity of the backup, should you need to restore from it.
-    </para>
-
-    <para>
-     By default, <function>pg_start_backup</function> can take a long time to finish.
-     This is because it performs a checkpoint, and the I/O
-     required for the checkpoint will be spread out over a significant
-     period of time, by default half your inter-checkpoint interval
-     (see the configuration parameter
-     <xref linkend="guc-checkpoint-completion-target"/>).  This is
-     usually what you want, because it minimizes the impact on query
-     processing.  If you want to start the backup as soon as
-     possible, use:
-<programlisting>
-SELECT pg_start_backup('label', true);
-</programlisting>
-     This forces the checkpoint to be done as quickly as possible.
-    </para>
-   </listitem>
-   <listitem>
-    <para>
-     Perform the backup, using any convenient file-system-backup tool
-     such as <application>tar</application> or <application>cpio</application> (not
-     <application>pg_dump</application> or
-     <application>pg_dumpall</application>).  It is neither
-     necessary nor desirable to stop normal operation of the database
-     while you do this. See
-     <xref linkend="backup-lowlevel-base-backup-data"/> for things to
-     consider during this backup.
-    </para>
-    <para>
-     As noted above, if the server crashes during the backup it may not be
-     possible to restart until the <filename>backup_label</filename> file has
-     been manually deleted from the <envar>PGDATA</envar> directory.  Note
-     that it is very important to never remove the
-     <filename>backup_label</filename> file when restoring a backup, because
-     this will result in corruption.  Confusion about when it is appropriate
-     to remove this file is a common cause of data corruption when using this
-     method; be very certain that you remove the file only on an existing
-     master and never when building a standby or restoring a backup, even if
-     you are building a standby that will subsequently be promoted to a new
-     master.
-    </para>
-   </listitem>
-   <listitem>
-    <para>
-     Again connect to the database as a user with rights to run
-     pg_stop_backup (superuser, or a user who has been granted EXECUTE on
-     the function), and issue the command:
-<programlisting>
-SELECT pg_stop_backup();
-</programlisting>
-     This function terminates backup mode and
-     performs an automatic switch to the next WAL segment. The reason for the
-     switch is to arrange for the last WAL segment written during the backup
-     interval to be ready to archive.
-    </para>
-   </listitem>
-   <listitem>
-    <para>
-     Once the WAL segment files active during the backup are archived, you are
-     done.  The file identified by <function>pg_stop_backup</function>'s result is
-     the last segment that is required to form a complete set of backup files.
-     If <varname>archive_mode</varname> is enabled,
-     <function>pg_stop_backup</function> does not return until the last segment has
-     been archived.
-     Archiving of these files happens automatically since you have
-     already configured <varname>archive_command</varname>. In most cases this
-     happens quickly, but you are advised to monitor your archive
-     system to ensure there are no delays.
-     If the archive process has fallen behind
-     because of failures of the archive command, it will keep retrying
-     until the archive succeeds and the backup is complete.
-    </para>
-
-    <para>
-     When using exclusive backup mode, it is absolutely imperative to ensure
-     that <function>pg_stop_backup</function> completes successfully at the
-     end of the backup.  Even if the backup itself fails, for example due to
-     lack of disk space, failure to call <function>pg_stop_backup</function>
-     will leave the server in backup mode indefinitely, causing future backups
-     to fail and increasing the risk of a restart failure during the time that
-     <filename>backup_label</filename> exists.
-    </para>
-   </listitem>
-  </orderedlist>
-    </para>
-   </sect3>
    <sect3 id="backup-lowlevel-base-backup-data">
    <title>Backing Up the Data Directory</title>
    <para>
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index f065856535..9e262fab3b 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -23990,9 +23990,7 @@ SELECT collation for ('foo' COLLATE "de_DE");
     The functions shown in <xref
     linkend="functions-admin-backup-table"/> assist in making on-line backups.
     These functions cannot be executed during recovery (except
-    non-exclusive <function>pg_start_backup</function>,
-    non-exclusive <function>pg_stop_backup</function>,
-    <function>pg_is_in_backup</function>, <function>pg_backup_start_time</function>
+    <function>pg_start_backup</function>, <function>pg_stop_backup</function>,
     and <function>pg_wal_lsn_diff</function>).
    </para>
 
@@ -24099,20 +24097,9 @@ SELECT collation for ('foo' COLLATE "de_DE");
         it specifies executing <function>pg_start_backup</function> as quickly
         as possible.  This forces an immediate checkpoint which will cause a
         spike in I/O operations, slowing any concurrently executing queries.
-        The optional third parameter specifies whether to perform an exclusive
-        or non-exclusive backup (default is exclusive).
-       </para>
-       <para>
-        When used in exclusive mode, this function writes a backup label file
-        (<filename>backup_label</filename>) and, if there are any links in
-        the <filename>pg_tblspc/</filename> directory, a tablespace map file
-        (<filename>tablespace_map</filename>) into the database cluster's data
-        directory, then performs a checkpoint, and then returns the backup's
-        starting write-ahead log location.  (The user can ignore this
-        result value, but it is provided in case it is useful.)  When used in
-        non-exclusive mode, the contents of these files are instead returned
-        by the <function>pg_stop_backup</function> function, and should be
-        copied to the backup area by the user.
+        The third parameter must be set explicitly <literal>false</literal>.
+        The default of <literal>true</literal> for an exclusive backup is no
+        longer supported.
        </para>
        <para>
         This function is restricted to superusers by default, but other users
@@ -24135,15 +24122,10 @@ SELECT collation for ('foo' COLLATE "de_DE");
         <parameter>spcmapfile</parameter> <type>text</type> )
        </para>
        <para>
-        Finishes performing an exclusive or non-exclusive on-line backup.
-        The <parameter>exclusive</parameter> parameter must match the
+        Finishes performing an on-line backup. The
+        <parameter>exclusive</parameter> parameter must be
+        <literal>false</literal> false to match the
         previous <function>pg_start_backup</function> call.
-        In an exclusive backup, <function>pg_stop_backup</function> removes
-        the backup label file and, if it exists, the tablespace map file
-        created by <function>pg_start_backup</function>.  In a non-exclusive
-        backup, the desired contents of these files are returned as part of
-        the result of the function, and should be written to files in the
-        backup area (not in the data directory).
        </para>
        <para>
         There is an optional second parameter of type <type>boolean</type>.
@@ -24174,9 +24156,9 @@ SELECT collation for ('foo' COLLATE "de_DE");
         The result of the function is a single record.
         The <parameter>lsn</parameter> column holds the backup's ending
         write-ahead log location (which again can be ignored).  The second and
-        third columns are <literal>NULL</literal> when ending an exclusive
-        backup; after a non-exclusive backup they hold the desired contents of
-        the label and tablespace map files.
+        third columns hold the contents of the label and tablespace map files,
+        which should be written to files in the backup area (not in the data
+        directory).
        </para>
        <para>
         This function is restricted to superusers by default, but other users
@@ -24184,50 +24166,6 @@ SELECT collation for ('foo' COLLATE "de_DE");
        </para></entry>
       </row>
 
-      <row>
-       <entry role="func_table_entry"><para role="func_signature">
-        <function>pg_stop_backup</function> ()
-        <returnvalue>pg_lsn</returnvalue>
-       </para>
-       <para>
-        Finishes performing an exclusive on-line backup.  This simplified
-        version is equivalent to <literal>pg_stop_backup(true,
-        true)</literal>, except that it only returns the <type>pg_lsn</type>
-        result.
-       </para>
-       <para>
-        This function is restricted to superusers by default, but other users
-        can be granted EXECUTE to run the function.
-       </para></entry>
-      </row>
-
-      <row>
-       <entry role="func_table_entry"><para role="func_signature">
-        <indexterm>
-         <primary>pg_is_in_backup</primary>
-        </indexterm>
-        <function>pg_is_in_backup</function> ()
-        <returnvalue>boolean</returnvalue>
-       </para>
-       <para>
-        Returns true if an on-line exclusive backup is in progress.
-       </para></entry>
-      </row>
-
-      <row>
-       <entry role="func_table_entry"><para role="func_signature">
-        <indexterm>
-         <primary>pg_backup_start_time</primary>
-        </indexterm>
-        <function>pg_backup_start_time</function> ()
-        <returnvalue>timestamp with time zone</returnvalue>
-       </para>
-       <para>
-        Returns the start time of the current on-line exclusive backup if one
-        is in progress, otherwise <literal>NULL</literal>.
-       </para></entry>
-      </row>
-
       <row>
        <entry role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index fd93bcfaeb..3f3902fddf 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -506,29 +506,6 @@ typedef union WALInsertLockPadded
 	char		pad[PG_CACHE_LINE_SIZE];
 } WALInsertLockPadded;
 
-/*
- * State of an exclusive backup, necessary to control concurrent activities
- * across sessions when working on exclusive backups.
- *
- * EXCLUSIVE_BACKUP_NONE means that there is no exclusive backup actually
- * running, to be more precise pg_start_backup() is not being executed for
- * an exclusive backup and there is no exclusive backup in progress.
- * EXCLUSIVE_BACKUP_STARTING means that pg_start_backup() is starting an
- * exclusive backup.
- * EXCLUSIVE_BACKUP_IN_PROGRESS means that pg_start_backup() has finished
- * running and an exclusive backup is in progress. pg_stop_backup() is
- * needed to finish it.
- * EXCLUSIVE_BACKUP_STOPPING means that pg_stop_backup() is stopping an
- * exclusive backup.
- */
-typedef enum ExclusiveBackupState
-{
-	EXCLUSIVE_BACKUP_NONE = 0,
-	EXCLUSIVE_BACKUP_STARTING,
-	EXCLUSIVE_BACKUP_IN_PROGRESS,
-	EXCLUSIVE_BACKUP_STOPPING
-} ExclusiveBackupState;
-
 /*
  * Session status of running backup, used for sanity checks in SQL-callable
  * functions to start and stop backups.
@@ -576,15 +553,12 @@ typedef struct XLogCtlInsert
 	bool		fullPageWrites;
 
 	/*
-	 * exclusiveBackupState indicates the state of an exclusive backup (see
-	 * comments of ExclusiveBackupState for more details). nonExclusiveBackups
-	 * is a counter indicating the number of streaming base backups currently
-	 * in progress. forcePageWrites is set to true when either of these is
-	 * non-zero. lastBackupStart is the latest checkpoint redo location used
-	 * as a starting point for an online backup.
+	 * runningBackups is a counter indicating the number of backups currently in
+	 * progress. forcePageWrites is set to true when either of these is
+	 * non-zero. lastBackupStart is the latest checkpoint redo location used as
+	 * a starting point for an online backup.
 	 */
-	ExclusiveBackupState exclusiveBackupState;
-	int			nonExclusiveBackups;
+	int			runningBackups;
 	XLogRecPtr	lastBackupStart;
 
 	/*
@@ -944,7 +918,6 @@ static void xlog_outrec(StringInfo buf, XLogReaderState *record);
 #endif
 static void xlog_outdesc(StringInfo buf, XLogReaderState *record);
 static void pg_start_backup_callback(int code, Datum arg);
-static void pg_stop_backup_callback(int code, Datum arg);
 static bool read_backup_label(XLogRecPtr *checkPointLoc,
 							  bool *backupEndRequired, bool *backupFromStandby);
 static bool read_tablespace_map(List **tablespaces);
@@ -9371,7 +9344,7 @@ CreateRestartPoint(int flags)
 		 * Ensure minRecoveryPoint is past the checkpoint record.  Normally,
 		 * this will have happened already while writing out dirty buffers,
 		 * but not necessarily - e.g. because no buffers were dirtied.  We do
-		 * this because a non-exclusive base backup uses minRecoveryPoint to
+		 * this because a backup performed in recovery uses minRecoveryPoint to
 		 * determine which WAL files must be included in the backup, and the
 		 * file (or files) containing the checkpoint record must be included,
 		 * at a minimum. Note that for an ordinary restart of recovery there's
@@ -10444,25 +10417,14 @@ issue_xlog_fsync(int fd, XLogSegNo segno)
 }
 
 /*
- * do_pg_start_backup
- *
- * Utility function called at the start of an online backup. It creates the
- * necessary starting checkpoint and constructs the backup label file.
+ * do_pg_start_backup is the workhorse of the user-visible pg_start_backup()
+ * function. It creates the necessary starting checkpoint and constructs the
+ * backup label and tablespace map.
  *
- * There are two kind of backups: exclusive and non-exclusive. An exclusive
- * backup is started with pg_start_backup(), and there can be only one active
- * at a time. The backup and tablespace map files of an exclusive backup are
- * written to $PGDATA/backup_label and $PGDATA/tablespace_map, and they are
- * removed by pg_stop_backup().
- *
- * A non-exclusive backup is used for the streaming base backups (see
- * src/backend/replication/basebackup.c). The difference to exclusive backups
- * is that the backup label and tablespace map files are not written to disk.
- * Instead, their would-be contents are returned in *labelfile and *tblspcmapfile,
- * and the caller is responsible for including them in the backup archive as
- * 'backup_label' and 'tablespace_map'. There can be many non-exclusive backups
- * active at the same time, and they don't conflict with an exclusive backup
- * either.
+ * The backup label and tablespace map contents are returned in *labelfile and
+ * *tblspcmapfile, and the caller is responsible for including them in the
+ * backup archive as 'backup_label' and 'tablespace_map'. There can be many
+ * backups active at the same time.
  *
  * tablespaces is required only when this function is called while
  * the streaming base backup requested by pg_basebackup is running.
@@ -10472,15 +10434,14 @@ issue_xlog_fsync(int fd, XLogSegNo segno)
  * utilities are not able to create symlinks while extracting files from tar.
  * However for consistency, the same is used for all platforms.
  *
- * needtblspcmapfile is true for the cases (exclusive backup and for
- * non-exclusive backup only when tar format is used for taking backup)
- * when backup needs to generate tablespace_map file, it is used to
- * embed escape character before newline character in tablespace path.
+ * needtblspcmapfile is true for the cases (only when tar format is used for
+ * taking backup) when backup needs to generate tablespace_map file, it is used
+ * to embed escape character before newline character in tablespace path.
  *
  * Returns the minimum WAL location that must be present to restore from this
  * backup, and the corresponding timeline ID in *starttli_p.
  *
- * Every successfully started non-exclusive backup must be stopped by calling
+ * Every successfully started backup must be stopped by calling
  * do_pg_stop_backup() or do_pg_abort_backup().
  *
  * It is the responsibility of the caller of this function to verify the
@@ -10491,7 +10452,6 @@ do_pg_start_backup(const char *backupidstr, bool fast, TimeLineID *starttli_p,
 				   StringInfo labelfile, List **tablespaces,
 				   StringInfo tblspcmapfile, bool needtblspcmapfile)
 {
-	bool		exclusive = (labelfile == NULL);
 	bool		backup_started_in_recovery = false;
 	XLogRecPtr	checkpointloc;
 	XLogRecPtr	startpoint;
@@ -10500,20 +10460,9 @@ do_pg_start_backup(const char *backupidstr, bool fast, TimeLineID *starttli_p,
 	char		strfbuf[128];
 	char		xlogfilename[MAXFNAMELEN];
 	XLogSegNo	_logSegNo;
-	struct stat stat_buf;
-	FILE	   *fp;
 
 	backup_started_in_recovery = RecoveryInProgress();
 
-	/*
-	 * Currently only non-exclusive backup can be taken during recovery.
-	 */
-	if (backup_started_in_recovery && exclusive)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("recovery is in progress"),
-				 errhint("WAL control functions cannot be executed during recovery.")));
-
 	/*
 	 * During recovery, we don't need to check WAL level. Because, if WAL
 	 * level is not sufficient, it's impossible to get here during recovery.
@@ -10552,30 +10501,12 @@ do_pg_start_backup(const char *backupidstr, bool fast, TimeLineID *starttli_p,
 	 * XLogInsertRecord().
 	 */
 	WALInsertLockAcquireExclusive();
-	if (exclusive)
-	{
-		/*
-		 * At first, mark that we're now starting an exclusive backup, to
-		 * ensure that there are no other sessions currently running
-		 * pg_start_backup() or pg_stop_backup().
-		 */
-		if (XLogCtl->Insert.exclusiveBackupState != EXCLUSIVE_BACKUP_NONE)
-		{
-			WALInsertLockRelease();
-			ereport(ERROR,
-					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-					 errmsg("a backup is already in progress"),
-					 errhint("Run pg_stop_backup() and try again.")));
-		}
-		XLogCtl->Insert.exclusiveBackupState = EXCLUSIVE_BACKUP_STARTING;
-	}
-	else
-		XLogCtl->Insert.nonExclusiveBackups++;
+	XLogCtl->Insert.runningBackups++;
 	XLogCtl->Insert.forcePageWrites = true;
 	WALInsertLockRelease();
 
 	/* Ensure we release forcePageWrites if fail below */
-	PG_ENSURE_ERROR_CLEANUP(pg_start_backup_callback, (Datum) BoolGetDatum(exclusive));
+	PG_ENSURE_ERROR_CLEANUP(pg_start_backup_callback, (Datum) 0);
 	{
 		bool		gotUniqueStartpoint = false;
 		DIR		   *tblspcdir;
@@ -10702,11 +10633,8 @@ do_pg_start_backup(const char *backupidstr, bool fast, TimeLineID *starttli_p,
 		XLogFileName(xlogfilename, starttli, _logSegNo, wal_segment_size);
 
 		/*
-		 * Construct tablespace_map file
+		 * Construct tablespace_map
 		 */
-		if (exclusive)
-			tblspcmapfile = makeStringInfo();
-
 		datadirpathlen = strlen(DataDir);
 
 		/* Collect information about all tablespaces */
@@ -10796,11 +10724,8 @@ do_pg_start_backup(const char *backupidstr, bool fast, TimeLineID *starttli_p,
 		FreeDir(tblspcdir);
 
 		/*
-		 * Construct backup label file
+		 * Construct backup_label
 		 */
-		if (exclusive)
-			labelfile = makeStringInfo();
-
 		/* Use the log timezone here, not the session timezone */
 		stamp_time = (pg_time_t) time(NULL);
 		pg_strftime(strfbuf, sizeof(strfbuf),
@@ -10810,122 +10735,19 @@ do_pg_start_backup(const char *backupidstr, bool fast, TimeLineID *starttli_p,
 						 (uint32) (startpoint >> 32), (uint32) startpoint, xlogfilename);
 		appendStringInfo(labelfile, "CHECKPOINT LOCATION: %X/%X\n",
 						 (uint32) (checkpointloc >> 32), (uint32) checkpointloc);
-		appendStringInfo(labelfile, "BACKUP METHOD: %s\n",
-						 exclusive ? "pg_start_backup" : "streamed");
+		appendStringInfo(labelfile, "BACKUP METHOD: streamed\n");
 		appendStringInfo(labelfile, "BACKUP FROM: %s\n",
 						 backup_started_in_recovery ? "standby" : "master");
 		appendStringInfo(labelfile, "START TIME: %s\n", strfbuf);
 		appendStringInfo(labelfile, "LABEL: %s\n", backupidstr);
 		appendStringInfo(labelfile, "START TIMELINE: %u\n", starttli);
-
-		/*
-		 * Okay, write the file, or return its contents to caller.
-		 */
-		if (exclusive)
-		{
-			/*
-			 * Check for existing backup label --- implies a backup is already
-			 * running.  (XXX given that we checked exclusiveBackupState
-			 * above, maybe it would be OK to just unlink any such label
-			 * file?)
-			 */
-			if (stat(BACKUP_LABEL_FILE, &stat_buf) != 0)
-			{
-				if (errno != ENOENT)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not stat file \"%s\": %m",
-									BACKUP_LABEL_FILE)));
-			}
-			else
-				ereport(ERROR,
-						(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-						 errmsg("a backup is already in progress"),
-						 errhint("If you're sure there is no backup in progress, remove file \"%s\" and try again.",
-								 BACKUP_LABEL_FILE)));
-
-			fp = AllocateFile(BACKUP_LABEL_FILE, "w");
-
-			if (!fp)
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not create file \"%s\": %m",
-								BACKUP_LABEL_FILE)));
-			if (fwrite(labelfile->data, labelfile->len, 1, fp) != 1 ||
-				fflush(fp) != 0 ||
-				pg_fsync(fileno(fp)) != 0 ||
-				ferror(fp) ||
-				FreeFile(fp))
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not write file \"%s\": %m",
-								BACKUP_LABEL_FILE)));
-			/* Allocated locally for exclusive backups, so free separately */
-			pfree(labelfile->data);
-			pfree(labelfile);
-
-			/* Write backup tablespace_map file. */
-			if (tblspcmapfile->len > 0)
-			{
-				if (stat(TABLESPACE_MAP, &stat_buf) != 0)
-				{
-					if (errno != ENOENT)
-						ereport(ERROR,
-								(errcode_for_file_access(),
-								 errmsg("could not stat file \"%s\": %m",
-										TABLESPACE_MAP)));
-				}
-				else
-					ereport(ERROR,
-							(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-							 errmsg("a backup is already in progress"),
-							 errhint("If you're sure there is no backup in progress, remove file \"%s\" and try again.",
-									 TABLESPACE_MAP)));
-
-				fp = AllocateFile(TABLESPACE_MAP, "w");
-
-				if (!fp)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not create file \"%s\": %m",
-									TABLESPACE_MAP)));
-				if (fwrite(tblspcmapfile->data, tblspcmapfile->len, 1, fp) != 1 ||
-					fflush(fp) != 0 ||
-					pg_fsync(fileno(fp)) != 0 ||
-					ferror(fp) ||
-					FreeFile(fp))
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not write file \"%s\": %m",
-									TABLESPACE_MAP)));
-			}
-
-			/* Allocated locally for exclusive backups, so free separately */
-			pfree(tblspcmapfile->data);
-			pfree(tblspcmapfile);
-		}
 	}
-	PG_END_ENSURE_ERROR_CLEANUP(pg_start_backup_callback, (Datum) BoolGetDatum(exclusive));
+	PG_END_ENSURE_ERROR_CLEANUP(pg_start_backup_callback, (Datum) 0);
 
 	/*
-	 * Mark that start phase has correctly finished for an exclusive backup.
-	 * Session-level locks are updated as well to reflect that state.
-	 *
-	 * Note that CHECK_FOR_INTERRUPTS() must not occur while updating backup
-	 * counters and session-level lock. Otherwise they can be updated
-	 * inconsistently, and which might cause do_pg_abort_backup() to fail.
+	 * Mark that the start phase has correctly finished for the backup.
 	 */
-	if (exclusive)
-	{
-		WALInsertLockAcquireExclusive();
-		XLogCtl->Insert.exclusiveBackupState = EXCLUSIVE_BACKUP_IN_PROGRESS;
-
-		/* Set session-level lock */
-		sessionBackupState = SESSION_BACKUP_EXCLUSIVE;
-		WALInsertLockRelease();
-	}
-	else
-		sessionBackupState = SESSION_BACKUP_NON_EXCLUSIVE;
+	sessionBackupState = SESSION_BACKUP_RUNNING;
 
 	/*
 	 * We're done.  As a convenience, return the starting WAL location.
@@ -10939,43 +10761,15 @@ do_pg_start_backup(const char *backupidstr, bool fast, TimeLineID *starttli_p,
 static void
 pg_start_backup_callback(int code, Datum arg)
 {
-	bool		exclusive = DatumGetBool(arg);
-
 	/* Update backup counters and forcePageWrites on failure */
 	WALInsertLockAcquireExclusive();
-	if (exclusive)
-	{
-		Assert(XLogCtl->Insert.exclusiveBackupState == EXCLUSIVE_BACKUP_STARTING);
-		XLogCtl->Insert.exclusiveBackupState = EXCLUSIVE_BACKUP_NONE;
-	}
-	else
-	{
-		Assert(XLogCtl->Insert.nonExclusiveBackups > 0);
-		XLogCtl->Insert.nonExclusiveBackups--;
-	}
 
-	if (XLogCtl->Insert.exclusiveBackupState == EXCLUSIVE_BACKUP_NONE &&
-		XLogCtl->Insert.nonExclusiveBackups == 0)
-	{
-		XLogCtl->Insert.forcePageWrites = false;
-	}
-	WALInsertLockRelease();
-}
+	Assert(XLogCtl->Insert.runningBackups > 0);
+	XLogCtl->Insert.runningBackups--;
 
-/*
- * Error cleanup callback for pg_stop_backup
- */
-static void
-pg_stop_backup_callback(int code, Datum arg)
-{
-	bool		exclusive = DatumGetBool(arg);
-
-	/* Update backup status on failure */
-	WALInsertLockAcquireExclusive();
-	if (exclusive)
+	if (XLogCtl->Insert.runningBackups == 0)
 	{
-		Assert(XLogCtl->Insert.exclusiveBackupState == EXCLUSIVE_BACKUP_STOPPING);
-		XLogCtl->Insert.exclusiveBackupState = EXCLUSIVE_BACKUP_IN_PROGRESS;
+		XLogCtl->Insert.forcePageWrites = false;
 	}
 	WALInsertLockRelease();
 }
@@ -10995,9 +10789,6 @@ get_backup_status(void)
  * Utility function called at the end of an online backup. It cleans up the
  * backup state and can optionally wait for WAL segments to be archived.
  *
- * If labelfile is NULL, this stops an exclusive backup. Otherwise this stops
- * the non-exclusive backup specified by 'labelfile'.
- *
  * Returns the last WAL location that must be present to restore from this
  * backup, and the corresponding timeline ID in *stoptli_p.
  *
@@ -11007,7 +10798,6 @@ get_backup_status(void)
 XLogRecPtr
 do_pg_stop_backup(char *labelfile, bool waitforarchive, TimeLineID *stoptli_p)
 {
-	bool		exclusive = (labelfile == NULL);
 	bool		backup_started_in_recovery = false;
 	XLogRecPtr	startpoint;
 	XLogRecPtr	stoppoint;
@@ -11021,7 +10811,6 @@ do_pg_stop_backup(char *labelfile, bool waitforarchive, TimeLineID *stoptli_p)
 	char		histfilename[MAXFNAMELEN];
 	char		backupfrom[20];
 	XLogSegNo	_logSegNo;
-	FILE	   *lfp;
 	FILE	   *fp;
 	char		ch;
 	int			seconds_before_warning;
@@ -11034,15 +10823,6 @@ do_pg_stop_backup(char *labelfile, bool waitforarchive, TimeLineID *stoptli_p)
 
 	backup_started_in_recovery = RecoveryInProgress();
 
-	/*
-	 * Currently only non-exclusive backup can be taken during recovery.
-	 */
-	if (backup_started_in_recovery && exclusive)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("recovery is in progress"),
-				 errhint("WAL control functions cannot be executed during recovery.")));
-
 	/*
 	 * During recovery, we don't need to check WAL level. Because, if WAL
 	 * level is not sufficient, it's impossible to get here during recovery.
@@ -11053,106 +10833,23 @@ do_pg_stop_backup(char *labelfile, bool waitforarchive, TimeLineID *stoptli_p)
 				 errmsg("WAL level not sufficient for making an online backup"),
 				 errhint("wal_level must be set to \"replica\" or \"logical\" at server start.")));
 
-	if (exclusive)
-	{
-		/*
-		 * At first, mark that we're now stopping an exclusive backup, to
-		 * ensure that there are no other sessions currently running
-		 * pg_start_backup() or pg_stop_backup().
-		 */
-		WALInsertLockAcquireExclusive();
-		if (XLogCtl->Insert.exclusiveBackupState != EXCLUSIVE_BACKUP_IN_PROGRESS)
-		{
-			WALInsertLockRelease();
-			ereport(ERROR,
-					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-					 errmsg("exclusive backup not in progress")));
-		}
-		XLogCtl->Insert.exclusiveBackupState = EXCLUSIVE_BACKUP_STOPPING;
-		WALInsertLockRelease();
-
-		/*
-		 * Remove backup_label. In case of failure, the state for an exclusive
-		 * backup is switched back to in-progress.
-		 */
-		PG_ENSURE_ERROR_CLEANUP(pg_stop_backup_callback, (Datum) BoolGetDatum(exclusive));
-		{
-			/*
-			 * Read the existing label file into memory.
-			 */
-			struct stat statbuf;
-			int			r;
-
-			if (stat(BACKUP_LABEL_FILE, &statbuf))
-			{
-				/* should not happen per the upper checks */
-				if (errno != ENOENT)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not stat file \"%s\": %m",
-									BACKUP_LABEL_FILE)));
-				ereport(ERROR,
-						(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-						 errmsg("a backup is not in progress")));
-			}
-
-			lfp = AllocateFile(BACKUP_LABEL_FILE, "r");
-			if (!lfp)
-			{
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not read file \"%s\": %m",
-								BACKUP_LABEL_FILE)));
-			}
-			labelfile = palloc(statbuf.st_size + 1);
-			r = fread(labelfile, statbuf.st_size, 1, lfp);
-			labelfile[statbuf.st_size] = '\0';
-
-			/*
-			 * Close and remove the backup label file
-			 */
-			if (r != 1 || ferror(lfp) || FreeFile(lfp))
-				ereport(ERROR,
-						(errcode_for_file_access(),
-						 errmsg("could not read file \"%s\": %m",
-								BACKUP_LABEL_FILE)));
-			durable_unlink(BACKUP_LABEL_FILE, ERROR);
-
-			/*
-			 * Remove tablespace_map file if present, it is created only if
-			 * there are tablespaces.
-			 */
-			durable_unlink(TABLESPACE_MAP, DEBUG1);
-		}
-		PG_END_ENSURE_ERROR_CLEANUP(pg_stop_backup_callback, (Datum) BoolGetDatum(exclusive));
-	}
-
 	/*
-	 * OK to update backup counters, forcePageWrites and session-level lock.
+	 * OK to update backup counters and forcePageWrites.
 	 *
 	 * Note that CHECK_FOR_INTERRUPTS() must not occur while updating them.
 	 * Otherwise they can be updated inconsistently, and which might cause
 	 * do_pg_abort_backup() to fail.
 	 */
 	WALInsertLockAcquireExclusive();
-	if (exclusive)
-	{
-		XLogCtl->Insert.exclusiveBackupState = EXCLUSIVE_BACKUP_NONE;
-	}
-	else
-	{
-		/*
-		 * The user-visible pg_start/stop_backup() functions that operate on
-		 * exclusive backups can be called at any time, but for non-exclusive
-		 * backups, it is expected that each do_pg_start_backup() call is
-		 * matched by exactly one do_pg_stop_backup() call.
-		 */
-		Assert(XLogCtl->Insert.nonExclusiveBackups > 0);
-		XLogCtl->Insert.nonExclusiveBackups--;
-	}
 
-	if (XLogCtl->Insert.exclusiveBackupState == EXCLUSIVE_BACKUP_NONE &&
-		XLogCtl->Insert.nonExclusiveBackups == 0)
+	/*
+	 * It is expected that each do_pg_start_backup() call is matched by exactly
+	 * one do_pg_stop_backup() call.
+	 */
+	Assert(XLogCtl->Insert.runningBackups > 0);
+	XLogCtl->Insert.runningBackups--;
+
+	if (XLogCtl->Insert.runningBackups == 0)
 	{
 		XLogCtl->Insert.forcePageWrites = false;
 	}
@@ -11410,10 +11107,6 @@ do_pg_stop_backup(char *labelfile, bool waitforarchive, TimeLineID *stoptli_p)
  * The caller can pass 'arg' as 'true' or 'false' to control whether a warning
  * is emitted.
  *
- * NB: This is only for aborting a non-exclusive backup that doesn't write
- * backup_label. A backup started with pg_start_backup() needs to be finished
- * with pg_stop_backup().
- *
  * NB: This gets used as a before_shmem_exit handler, hence the odd-looking
  * signature.
  */
@@ -11423,18 +11116,16 @@ do_pg_abort_backup(int code, Datum arg)
 	bool		emit_warning = DatumGetBool(arg);
 
 	/*
-	 * Quick exit if session is not keeping around a non-exclusive backup
-	 * already started.
+	 * Quick exit if session does not have a running backup.
 	 */
-	if (sessionBackupState != SESSION_BACKUP_NON_EXCLUSIVE)
+	if (sessionBackupState != SESSION_BACKUP_RUNNING)
 		return;
 
 	WALInsertLockAcquireExclusive();
-	Assert(XLogCtl->Insert.nonExclusiveBackups > 0);
-	XLogCtl->Insert.nonExclusiveBackups--;
+	Assert(XLogCtl->Insert.runningBackups > 0);
+	XLogCtl->Insert.runningBackups--;
 
-	if (XLogCtl->Insert.exclusiveBackupState == EXCLUSIVE_BACKUP_NONE &&
-		XLogCtl->Insert.nonExclusiveBackups == 0)
+	if (XLogCtl->Insert.runningBackups == 0)
 	{
 		XLogCtl->Insert.forcePageWrites = false;
 	}
@@ -11756,87 +11447,6 @@ rm_redo_error_callback(void *arg)
 	pfree(buf.data);
 }
 
-/*
- * BackupInProgress: check if online backup mode is active
- *
- * This is done by checking for existence of the "backup_label" file.
- */
-bool
-BackupInProgress(void)
-{
-	struct stat stat_buf;
-
-	return (stat(BACKUP_LABEL_FILE, &stat_buf) == 0);
-}
-
-/*
- * CancelBackup: rename the "backup_label" and "tablespace_map"
- *				 files to cancel backup mode
- *
- * If the "backup_label" file exists, it will be renamed to "backup_label.old".
- * Similarly, if the "tablespace_map" file exists, it will be renamed to
- * "tablespace_map.old".
- *
- * Note that this will render an online backup in progress
- * useless. To correctly finish an online backup, pg_stop_backup must be
- * called.
- */
-void
-CancelBackup(void)
-{
-	struct stat stat_buf;
-
-	/* if the backup_label file is not there, return */
-	if (stat(BACKUP_LABEL_FILE, &stat_buf) < 0)
-		return;
-
-	/* remove leftover file from previously canceled backup if it exists */
-	unlink(BACKUP_LABEL_OLD);
-
-	if (durable_rename(BACKUP_LABEL_FILE, BACKUP_LABEL_OLD, DEBUG1) != 0)
-	{
-		ereport(WARNING,
-				(errcode_for_file_access(),
-				 errmsg("online backup mode was not canceled"),
-				 errdetail("File \"%s\" could not be renamed to \"%s\": %m.",
-						   BACKUP_LABEL_FILE, BACKUP_LABEL_OLD)));
-		return;
-	}
-
-	/* if the tablespace_map file is not there, return */
-	if (stat(TABLESPACE_MAP, &stat_buf) < 0)
-	{
-		ereport(LOG,
-				(errmsg("online backup mode canceled"),
-				 errdetail("File \"%s\" was renamed to \"%s\".",
-						   BACKUP_LABEL_FILE, BACKUP_LABEL_OLD)));
-		return;
-	}
-
-	/* remove leftover file from previously canceled backup if it exists */
-	unlink(TABLESPACE_MAP_OLD);
-
-	if (durable_rename(TABLESPACE_MAP, TABLESPACE_MAP_OLD, DEBUG1) == 0)
-	{
-		ereport(LOG,
-				(errmsg("online backup mode canceled"),
-				 errdetail("Files \"%s\" and \"%s\" were renamed to "
-						   "\"%s\" and \"%s\", respectively.",
-						   BACKUP_LABEL_FILE, TABLESPACE_MAP,
-						   BACKUP_LABEL_OLD, TABLESPACE_MAP_OLD)));
-	}
-	else
-	{
-		ereport(WARNING,
-				(errcode_for_file_access(),
-				 errmsg("online backup mode canceled"),
-				 errdetail("File \"%s\" was renamed to \"%s\", but "
-						   "file \"%s\" could not be renamed to \"%s\": %m.",
-						   BACKUP_LABEL_FILE, BACKUP_LABEL_OLD,
-						   TABLESPACE_MAP, TABLESPACE_MAP_OLD)));
-	}
-}
-
 /*
  * Read the XLOG page containing RecPtr into readBuf (if not read already).
  * Returns number of bytes read, if the page is read successfully, or -1
diff --git a/src/backend/access/transam/xlogfuncs.c b/src/backend/access/transam/xlogfuncs.c
index 290658b22c..ec3669b4ae 100644
--- a/src/backend/access/transam/xlogfuncs.c
+++ b/src/backend/access/transam/xlogfuncs.c
@@ -39,7 +39,7 @@
 #include "utils/tuplestore.h"
 
 /*
- * Store label file and tablespace map during non-exclusive backups.
+ * Store label file and tablespace map during backups.
  */
 static StringInfo label_file;
 static StringInfo tblspc_map_file;
@@ -61,101 +61,46 @@ pg_start_backup(PG_FUNCTION_ARGS)
 {
 	text	   *backupid = PG_GETARG_TEXT_PP(0);
 	bool		fast = PG_GETARG_BOOL(1);
-	bool		exclusive = PG_GETARG_BOOL(2);
 	char	   *backupidstr;
 	XLogRecPtr	startpoint;
 	SessionBackupState status = get_backup_status();
+	MemoryContext oldcontext;
 
 	backupidstr = text_to_cstring(backupid);
 
-	if (status == SESSION_BACKUP_NON_EXCLUSIVE)
+	/* Error if exclusive backup mode is requested */
+	if (PG_GETARG_BOOL(2))
 		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("a backup is already in progress in this session")));
-
-	if (exclusive)
-	{
-		startpoint = do_pg_start_backup(backupidstr, fast, NULL, NULL,
-										NULL, NULL, true);
-	}
-	else
-	{
-		MemoryContext oldcontext;
-
-		/*
-		 * Label file and tablespace map file need to be long-lived, since
-		 * they are read in pg_stop_backup.
-		 */
-		oldcontext = MemoryContextSwitchTo(TopMemoryContext);
-		label_file = makeStringInfo();
-		tblspc_map_file = makeStringInfo();
-		MemoryContextSwitchTo(oldcontext);
-
-		register_persistent_abort_backup_handler();
-
-		startpoint = do_pg_start_backup(backupidstr, fast, NULL, label_file,
-										NULL, tblspc_map_file, true);
-	}
-
-	PG_RETURN_LSN(startpoint);
-}
-
-/*
- * pg_stop_backup: finish taking an on-line backup dump
- *
- * We write an end-of-backup WAL record, and remove the backup label file
- * created by pg_start_backup, creating a backup history file in pg_wal
- * instead (whence it will immediately be archived). The backup history file
- * contains the same info found in the label file, plus the backup-end time
- * and WAL location. Before 9.0, the backup-end time was read from the backup
- * history file at the beginning of archive recovery, but we now use the WAL
- * record for that and the file is for informational and debug purposes only.
- *
- * Note: different from CancelBackup which just cancels online backup mode.
- *
- * Note: this version is only called to stop an exclusive backup. The function
- *		 pg_stop_backup_v2 (overloaded as pg_stop_backup in SQL) is called to
- *		 stop non-exclusive backups.
- *
- * Permission checking for this function is managed through the normal
- * GRANT system.
- */
-Datum
-pg_stop_backup(PG_FUNCTION_ARGS)
-{
-	XLogRecPtr	stoppoint;
-	SessionBackupState status = get_backup_status();
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("exclusive backup mode is no longer supported")));
 
-	if (status == SESSION_BACKUP_NON_EXCLUSIVE)
+	if (status == SESSION_BACKUP_RUNNING)
 		ereport(ERROR,
 				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("non-exclusive backup in progress"),
-				 errhint("Did you mean to use pg_stop_backup('f')?")));
+				 errmsg("a backup is already in progress in this session")));
 
 	/*
-	 * Exclusive backups were typically started in a different connection, so
-	 * don't try to verify that status of backup is set to
-	 * SESSION_BACKUP_EXCLUSIVE in this function. Actual verification that an
-	 * exclusive backup is in fact running is handled inside
-	 * do_pg_stop_backup.
+	 * Label file and tablespace map file need to be long-lived, since
+	 * they are read in pg_stop_backup.
 	 */
-	stoppoint = do_pg_stop_backup(NULL, true, NULL);
+	oldcontext = MemoryContextSwitchTo(TopMemoryContext);
+	label_file = makeStringInfo();
+	tblspc_map_file = makeStringInfo();
+	MemoryContextSwitchTo(oldcontext);
 
-	PG_RETURN_LSN(stoppoint);
+	register_persistent_abort_backup_handler();
+
+	startpoint = do_pg_start_backup(backupidstr, fast, NULL, label_file,
+									NULL, tblspc_map_file, true);
+
+	PG_RETURN_LSN(startpoint);
 }
 
 
 /*
- * pg_stop_backup_v2: finish taking exclusive or nonexclusive on-line backup.
+ * pg_stop_backup: finish taking an on-line backup.
  *
- * Works the same as pg_stop_backup, except for non-exclusive backups it returns
- * the backup label and tablespace map files as text fields in as part of the
- * resultset.
- *
- * The first parameter (variable 'exclusive') allows the user to tell us if
- * this is an exclusive or a non-exclusive backup.
- *
- * The second parameter (variable 'waitforarchive'), which is optional,
+ * The first parameter (variable 'waitforarchive'), which is optional,
  * allows the user to choose if they want to wait for the WAL to be archived
  * or if we should just return as soon as the WAL record is written.
  *
@@ -163,7 +108,7 @@ pg_stop_backup(PG_FUNCTION_ARGS)
  * GRANT system.
  */
 Datum
-pg_stop_backup_v2(PG_FUNCTION_ARGS)
+pg_stop_backup(PG_FUNCTION_ARGS)
 {
 	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
 	TupleDesc	tupdesc;
@@ -173,11 +118,16 @@ pg_stop_backup_v2(PG_FUNCTION_ARGS)
 	Datum		values[3];
 	bool		nulls[3];
 
-	bool		exclusive = PG_GETARG_BOOL(0);
 	bool		waitforarchive = PG_GETARG_BOOL(1);
 	XLogRecPtr	stoppoint;
 	SessionBackupState status = get_backup_status();
 
+	/* Error if exclusive backup mode is requested */
+	if (PG_GETARG_BOOL(0))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("exclusive backup mode is no longer supported")));
+
 	/* check to see if caller supports us returning a tuplestore */
 	if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
 		ereport(ERROR,
@@ -205,51 +155,29 @@ pg_stop_backup_v2(PG_FUNCTION_ARGS)
 	MemSet(values, 0, sizeof(values));
 	MemSet(nulls, 0, sizeof(nulls));
 
-	if (exclusive)
-	{
-		if (status == SESSION_BACKUP_NON_EXCLUSIVE)
-			ereport(ERROR,
-					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-					 errmsg("non-exclusive backup in progress"),
-					 errhint("Did you mean to use pg_stop_backup('f')?")));
-
-		/*
-		 * Stop the exclusive backup, and since we're in an exclusive backup
-		 * return NULL for both backup_label and tablespace_map.
-		 */
-		stoppoint = do_pg_stop_backup(NULL, waitforarchive, NULL);
-
-		nulls[1] = true;
-		nulls[2] = true;
-	}
-	else
-	{
-		if (status != SESSION_BACKUP_NON_EXCLUSIVE)
-			ereport(ERROR,
-					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-					 errmsg("non-exclusive backup is not in progress"),
-					 errhint("Did you mean to use pg_stop_backup('t')?")));
+	if (status != SESSION_BACKUP_RUNNING)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("backup is not in progress"),
+				 errhint("Did you call pg_start_backup()?")));
 
-		/*
-		 * Stop the non-exclusive backup. Return a copy of the backup label
-		 * and tablespace map so they can be written to disk by the caller.
-		 */
-		stoppoint = do_pg_stop_backup(label_file->data, waitforarchive, NULL);
-
-		values[1] = CStringGetTextDatum(label_file->data);
-		values[2] = CStringGetTextDatum(tblspc_map_file->data);
-
-		/* Free structures allocated in TopMemoryContext */
-		pfree(label_file->data);
-		pfree(label_file);
-		label_file = NULL;
-		pfree(tblspc_map_file->data);
-		pfree(tblspc_map_file);
-		tblspc_map_file = NULL;
-	}
+	/*
+	 * Stop the backup. Return a copy of the backup label and tablespace map so
+	 * they can be written to disk by the caller.
+	 */
+	stoppoint = do_pg_stop_backup(label_file->data, waitforarchive, NULL);
 
-	/* Stoppoint is included on both exclusive and nonexclusive backups */
 	values[0] = LSNGetDatum(stoppoint);
+	values[1] = CStringGetTextDatum(label_file->data);
+	values[2] = CStringGetTextDatum(tblspc_map_file->data);
+
+	/* Free structures allocated in TopMemoryContext */
+	pfree(label_file->data);
+	pfree(label_file);
+	label_file = NULL;
+	pfree(tblspc_map_file->data);
+	pfree(tblspc_map_file);
+	tblspc_map_file = NULL;
 
 	tuplestore_putvalues(tupstore, tupdesc, values, nulls);
 	tuplestore_donestoring(tupstore);
@@ -627,81 +555,6 @@ pg_wal_lsn_diff(PG_FUNCTION_ARGS)
 	PG_RETURN_NUMERIC(result);
 }
 
-/*
- * Returns bool with current on-line backup mode, a global state.
- */
-Datum
-pg_is_in_backup(PG_FUNCTION_ARGS)
-{
-	PG_RETURN_BOOL(BackupInProgress());
-}
-
-/*
- * Returns start time of an online exclusive backup.
- *
- * When there's no exclusive backup in progress, the function
- * returns NULL.
- */
-Datum
-pg_backup_start_time(PG_FUNCTION_ARGS)
-{
-	Datum		xtime;
-	FILE	   *lfp;
-	char		fline[MAXPGPATH];
-	char		backup_start_time[30];
-
-	/*
-	 * See if label file is present
-	 */
-	lfp = AllocateFile(BACKUP_LABEL_FILE, "r");
-	if (lfp == NULL)
-	{
-		if (errno != ENOENT)
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read file \"%s\": %m",
-							BACKUP_LABEL_FILE)));
-		PG_RETURN_NULL();
-	}
-
-	/*
-	 * Parse the file to find the START TIME line.
-	 */
-	backup_start_time[0] = '\0';
-	while (fgets(fline, sizeof(fline), lfp) != NULL)
-	{
-		if (sscanf(fline, "START TIME: %25[^\n]\n", backup_start_time) == 1)
-			break;
-	}
-
-	/* Check for a read error. */
-	if (ferror(lfp))
-		ereport(ERROR,
-				(errcode_for_file_access(),
-				 errmsg("could not read file \"%s\": %m", BACKUP_LABEL_FILE)));
-
-	/* Close the backup label file. */
-	if (FreeFile(lfp))
-		ereport(ERROR,
-				(errcode_for_file_access(),
-				 errmsg("could not close file \"%s\": %m", BACKUP_LABEL_FILE)));
-
-	if (strlen(backup_start_time) == 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("invalid data in file \"%s\"", BACKUP_LABEL_FILE)));
-
-	/*
-	 * Convert the time string read from file to TimestampTz form.
-	 */
-	xtime = DirectFunctionCall3(timestamptz_in,
-								CStringGetDatum(backup_start_time),
-								ObjectIdGetDatum(InvalidOid),
-								Int32GetDatum(-1));
-
-	PG_RETURN_DATUM(xtime);
-}
-
 /*
  * Promotes a standby server.
  *
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 5314e9348f..cce0e504a0 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1214,7 +1214,7 @@ CREATE OR REPLACE FUNCTION
 CREATE OR REPLACE FUNCTION pg_stop_backup (
         exclusive boolean, wait_for_archive boolean DEFAULT true,
         OUT lsn pg_lsn, OUT labelfile text, OUT spcmapfile text)
-  RETURNS SETOF record STRICT VOLATILE LANGUAGE internal as 'pg_stop_backup_v2'
+  RETURNS SETOF record STRICT VOLATILE LANGUAGE internal as 'pg_stop_backup'
   PARALLEL RESTRICTED;
 
 CREATE OR REPLACE FUNCTION
@@ -1427,7 +1427,6 @@ AS 'unicode_is_normalized';
 -- available to superuser / cluster owner, if they choose.
 --
 REVOKE EXECUTE ON FUNCTION pg_start_backup(text, boolean, boolean) FROM public;
-REVOKE EXECUTE ON FUNCTION pg_stop_backup() FROM public;
 REVOKE EXECUTE ON FUNCTION pg_stop_backup(boolean, boolean) FROM public;
 REVOKE EXECUTE ON FUNCTION pg_create_restore_point(text) FROM public;
 REVOKE EXECUTE ON FUNCTION pg_switch_wal() FROM public;
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index b4d475bb0b..05c44c7ec3 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -300,8 +300,7 @@ static bool FatalError = false; /* T if recovering from backend crash */
  * and we switch to PM_RUN state.
  *
  * Normal child backends can only be launched when we are in PM_RUN or
- * PM_HOT_STANDBY state.  (We also allow launch of normal
- * child backends in PM_WAIT_BACKUP state, but only for superusers.)
+ * PM_HOT_STANDBY state.
  * In other states we handle connection requests by launching "dead_end"
  * child processes, which will simply send the client an error message and
  * quit.  (We track these in the BackendList so that we can know when they
@@ -327,7 +326,6 @@ typedef enum
 	PM_RECOVERY,				/* in archive recovery mode */
 	PM_HOT_STANDBY,				/* in hot standby mode */
 	PM_RUN,						/* normal "database is alive" state */
-	PM_WAIT_BACKUP,				/* waiting for online backup mode to end */
 	PM_WAIT_READONLY,			/* waiting for read only backends to exit */
 	PM_WAIT_BACKENDS,			/* waiting for live backends to exit */
 	PM_SHUTDOWN,				/* waiting for checkpointer to do shutdown
@@ -2320,9 +2318,6 @@ retry1:
 					(errcode(ERRCODE_TOO_MANY_CONNECTIONS),
 					 errmsg("sorry, too many clients already")));
 			break;
-		case CAC_WAITBACKUP:
-			/* OK for now, will check in InitPostgres */
-			break;
 		case CAC_OK:
 			break;
 	}
@@ -2440,19 +2435,11 @@ canAcceptConnections(int backend_type)
 	 * state.  We treat autovac workers the same as user backends for this
 	 * purpose.  However, bgworkers are excluded from this test; we expect
 	 * bgworker_should_start_now() decided whether the DB state allows them.
-	 *
-	 * In state PM_WAIT_BACKUP only superusers can connect (this must be
-	 * allowed so that a superuser can end online backup mode); we return
-	 * CAC_WAITBACKUP code to indicate that this must be checked later. Note
-	 * that neither CAC_OK nor CAC_WAITBACKUP can safely be returned until we
-	 * have checked for too many children.
 	 */
 	if (pmState != PM_RUN &&
 		backend_type != BACKEND_TYPE_BGWORKER)
 	{
-		if (pmState == PM_WAIT_BACKUP)
-			result = CAC_WAITBACKUP;	/* allow superusers only */
-		else if (Shutdown > NoShutdown)
+		if (Shutdown > NoShutdown)
 			return CAC_SHUTDOWN;	/* shutdown is pending */
 		else if (!FatalError &&
 				 (pmState == PM_STARTUP ||
@@ -2817,7 +2804,7 @@ pmdie(SIGNAL_ARGS)
 				 * and walreceiver processes.
 				 */
 				pmState = (pmState == PM_RUN) ?
-					PM_WAIT_BACKUP : PM_WAIT_READONLY;
+					PM_WAIT_BACKENDS : PM_WAIT_READONLY;
 			}
 
 			/*
@@ -2867,7 +2854,6 @@ pmdie(SIGNAL_ARGS)
 				pmState = PM_WAIT_BACKENDS;
 			}
 			else if (pmState == PM_RUN ||
-					 pmState == PM_WAIT_BACKUP ||
 					 pmState == PM_WAIT_READONLY ||
 					 pmState == PM_WAIT_BACKENDS ||
 					 pmState == PM_HOT_STANDBY)
@@ -3709,7 +3695,6 @@ HandleChildCrash(int pid, int exitstatus, const char *procname)
 	if (pmState == PM_RECOVERY ||
 		pmState == PM_HOT_STANDBY ||
 		pmState == PM_RUN ||
-		pmState == PM_WAIT_BACKUP ||
 		pmState == PM_WAIT_READONLY ||
 		pmState == PM_SHUTDOWN)
 		pmState = PM_WAIT_BACKENDS;
@@ -3793,15 +3778,6 @@ LogChildExit(int lev, const char *procname, int pid, int exitstatus)
 static void
 PostmasterStateMachine(void)
 {
-	if (pmState == PM_WAIT_BACKUP)
-	{
-		/*
-		 * PM_WAIT_BACKUP state ends when online backup mode is not active.
-		 */
-		if (!BackupInProgress())
-			pmState = PM_WAIT_BACKENDS;
-	}
-
 	if (pmState == PM_WAIT_READONLY)
 	{
 		/*
@@ -3967,18 +3943,6 @@ PostmasterStateMachine(void)
 		}
 		else
 		{
-			/*
-			 * Terminate exclusive backup mode to avoid recovery after a clean
-			 * fast shutdown.  Since an exclusive backup can only be taken
-			 * during normal running (and not, for example, while running
-			 * under Hot Standby) it only makes sense to do this if we reached
-			 * normal running. If we're still in recovery, the backup file is
-			 * one we're recovering *from*, and we must keep it around so that
-			 * recovery restarts from the right place.
-			 */
-			if (ReachedNormalRunning)
-				CancelBackup();
-
 			/* Normal exit from the postmaster is here */
 			ExitPostmaster(0);
 		}
@@ -4180,8 +4144,7 @@ BackendStartup(Port *port)
 
 	/* Pass down canAcceptConnections state */
 	port->canAcceptConnections = canAcceptConnections(BACKEND_TYPE_NORMAL);
-	bn->dead_end = (port->canAcceptConnections != CAC_OK &&
-					port->canAcceptConnections != CAC_WAITBACKUP);
+	bn->dead_end = port->canAcceptConnections != CAC_OK;
 
 	/*
 	 * Unless it's a dead_end child, assign it a child slot number
@@ -5898,7 +5861,6 @@ bgworker_should_start_now(BgWorkerStartTime start_time)
 		case PM_SHUTDOWN:
 		case PM_WAIT_BACKENDS:
 		case PM_WAIT_READONLY:
-		case PM_WAIT_BACKUP:
 			break;
 
 		case PM_RUN:
diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
index 096b0fcef0..1440180cc4 100644
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -206,10 +206,8 @@ static const struct exclude_list_item excludeFiles[] =
 	{RELCACHE_INIT_FILENAME, true},
 
 	/*
-	 * If there's a backup_label or tablespace_map file, it belongs to a
-	 * backup started by the user with pg_start_backup().  It is *not* correct
-	 * for this backup.  Our backup_label/tablespace_map is injected into the
-	 * tar separately.
+	 * backup_label and tablespace_map should not exist in in a running cluster
+	 * capable of doing an online backup, but exclude them just in case.
 	 */
 	{BACKUP_LABEL_FILE, false},
 	{TABLESPACE_MAP, false},
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index f4247ea70d..2e1d4e1c40 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -791,7 +791,7 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 	 */
 	if ((!am_superuser || am_walsender) &&
 		MyProcPort != NULL &&
-		MyProcPort->canAcceptConnections == CAC_WAITBACKUP)
+		MyProcPort->canAcceptConnections == CAC_SHUTDOWN)
 	{
 		if (am_walsender)
 			ereport(FATAL,
diff --git a/src/bin/pg_basebackup/t/010_pg_basebackup.pl b/src/bin/pg_basebackup/t/010_pg_basebackup.pl
index 208df557b8..90af0d6272 100644
--- a/src/bin/pg_basebackup/t/010_pg_basebackup.pl
+++ b/src/bin/pg_basebackup/t/010_pg_basebackup.pl
@@ -159,6 +159,10 @@ isnt(slurp_file("$tempdir/backup/backup_label"),
 	'DONOTCOPY', 'existing backup_label not copied');
 rmtree("$tempdir/backup");
 
+# Now delete the bogus backup_label file since it will interfere with startup
+unlink("$pgdata/backup_label")
+  or BAIL_OUT("unable to unlink $pgdata/backup_label");
+
 $node->command_ok(
 	[
 		'pg_basebackup',    '-D',
diff --git a/src/bin/pg_rewind/filemap.c b/src/bin/pg_rewind/filemap.c
index 36a2d62341..1485eff3e1 100644
--- a/src/bin/pg_rewind/filemap.c
+++ b/src/bin/pg_rewind/filemap.c
@@ -106,9 +106,9 @@ static const struct exclude_list_item excludeFiles[] =
 	{"pg_internal.init", true}, /* defined as RELCACHE_INIT_FILENAME */
 
 	/*
-	 * If there's a backup_label or tablespace_map file, it belongs to a
-	 * backup started by the user with pg_start_backup().  It is *not* correct
-	 * for this backup.  Our backup_label is written later on separately.
+	 * If there is a backup_label or tablespace_map file, it indicates that
+	 * a recovery failed and this cluster probably can't be rewound, but
+	 * exclude them anyway if they are found.
 	 */
 	{"backup_label", false},	/* defined as BACKUP_LABEL_FILE */
 	{"tablespace_map", false},	/* defined as TABLESPACE_MAP */
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 77ac4e785f..b99ef3ecb4 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -368,8 +368,7 @@ extern void assign_checkpoint_completion_target(double newval, void *extra);
 typedef enum SessionBackupState
 {
 	SESSION_BACKUP_NONE,
-	SESSION_BACKUP_EXCLUSIVE,
-	SESSION_BACKUP_NON_EXCLUSIVE
+	SESSION_BACKUP_RUNNING,
 } SessionBackupState;
 
 extern XLogRecPtr do_pg_start_backup(const char *backupidstr, bool fast,
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 61f2c2f5b4..4135e588fd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6051,23 +6051,13 @@
   proname => 'pg_start_backup', provolatile => 'v', proparallel => 'r',
   prorettype => 'pg_lsn', proargtypes => 'text bool bool',
   prosrc => 'pg_start_backup' },
-{ oid => '2173', descr => 'finish taking an online backup',
-  proname => 'pg_stop_backup', provolatile => 'v', proparallel => 'r',
-  prorettype => 'pg_lsn', proargtypes => '', prosrc => 'pg_stop_backup' },
 { oid => '2739', descr => 'finish taking an online backup',
   proname => 'pg_stop_backup', prorows => '1', proretset => 't',
   provolatile => 'v', proparallel => 'r', prorettype => 'record',
   proargtypes => 'bool bool', proallargtypes => '{bool,bool,pg_lsn,text,text}',
   proargmodes => '{i,i,o,o,o}',
   proargnames => '{exclusive,wait_for_archive,lsn,labelfile,spcmapfile}',
-  prosrc => 'pg_stop_backup_v2' },
-{ oid => '3813', descr => 'true if server is in online backup',
-  proname => 'pg_is_in_backup', provolatile => 'v', prorettype => 'bool',
-  proargtypes => '', prosrc => 'pg_is_in_backup' },
-{ oid => '3814', descr => 'start time of an online backup',
-  proname => 'pg_backup_start_time', provolatile => 's',
-  prorettype => 'timestamptz', proargtypes => '',
-  prosrc => 'pg_backup_start_time' },
+  prosrc => 'pg_stop_backup' },
 { oid => '3436', descr => 'promote standby server',
   proname => 'pg_promote', provolatile => 'v', prorettype => 'bool',
   proargtypes => 'bool int4', proargnames => '{wait,wait_seconds}',
diff --git a/src/include/libpq/libpq-be.h b/src/include/libpq/libpq-be.h
index 179ebaa104..66e527dec8 100644
--- a/src/include/libpq/libpq-be.h
+++ b/src/include/libpq/libpq-be.h
@@ -70,8 +70,7 @@ typedef struct
 
 typedef enum CAC_state
 {
-	CAC_OK, CAC_STARTUP, CAC_SHUTDOWN, CAC_RECOVERY, CAC_TOOMANY,
-	CAC_WAITBACKUP
+	CAC_OK, CAC_STARTUP, CAC_SHUTDOWN, CAC_RECOVERY, CAC_TOOMANY
 } CAC_state;
 
 
diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h
index 18bc8a7b90..ddea0c9f33 100644
--- a/src/include/miscadmin.h
+++ b/src/include/miscadmin.h
@@ -465,8 +465,4 @@ extern void process_session_preload_libraries(void);
 extern void pg_bindtextdomain(const char *domain);
 extern bool has_rolreplication(Oid roleid);
 
-/* in access/transam/xlog.c */
-extern bool BackupInProgress(void);
-extern void CancelBackup(void);
-
 #endif							/* MISCADMIN_H */
diff --git a/src/test/perl/PostgresNode.pm b/src/test/perl/PostgresNode.pm
index 1407359aef..f580090e9a 100644
--- a/src/test/perl/PostgresNode.pm
+++ b/src/test/perl/PostgresNode.pm
@@ -557,25 +557,6 @@ sub backup
 	return;
 }
 
-=item $node->backup_fs_hot(backup_name)
-
-Create a backup with a filesystem level copy in subdirectory B<backup_name> of
-B<< $node->backup_dir >>, including WAL.
-
-Archiving must be enabled, as B<pg_start_backup()> and B<pg_stop_backup()> are
-used. This is not checked or enforced.
-
-The backup name is passed as the backup label to B<pg_start_backup()>.
-
-=cut
-
-sub backup_fs_hot
-{
-	my ($self, $backup_name) = @_;
-	$self->_backup_fs($backup_name, 1);
-	return;
-}
-
 =item $node->backup_fs_cold(backup_name)
 
 Create a backup with a filesystem level copy in subdirectory B<backup_name> of
@@ -589,53 +570,18 @@ Use B<backup> or B<backup_fs_hot> if you want to back up a running server.
 sub backup_fs_cold
 {
 	my ($self, $backup_name) = @_;
-	$self->_backup_fs($backup_name, 0);
-	return;
-}
-
-
-# Common sub of backup_fs_hot and backup_fs_cold
-sub _backup_fs
-{
-	my ($self, $backup_name, $hot) = @_;
-	my $backup_path = $self->backup_dir . '/' . $backup_name;
-	my $port        = $self->port;
-	my $name        = $self->name;
-
-	print "# Taking filesystem backup $backup_name from node \"$name\"\n";
-
-	if ($hot)
-	{
-		my $stdout = $self->safe_psql('postgres',
-			"SELECT * FROM pg_start_backup('$backup_name');");
-		print "# pg_start_backup: $stdout\n";
-	}
 
 	RecursiveCopy::copypath(
 		$self->data_dir,
-		$backup_path,
+		$self->backup_dir . '/' . $backup_name,
 		filterfn => sub {
 			my $src = shift;
 			return ($src ne 'log' and $src ne 'postmaster.pid');
 		});
 
-	if ($hot)
-	{
-
-		# We ignore pg_stop_backup's return value. We also assume archiving
-		# is enabled; otherwise the caller will have to copy the remaining
-		# segments.
-		my $stdout =
-		  $self->safe_psql('postgres', 'SELECT * FROM pg_stop_backup();');
-		print "# pg_stop_backup: $stdout\n";
-	}
-
-	print "# Backup finished\n";
 	return;
 }
 
-
-
 =pod
 
 =item $node->init_from_backup(root_node, backup_name)
diff --git a/src/test/recovery/t/010_logical_decoding_timelines.pl b/src/test/recovery/t/010_logical_decoding_timelines.pl
index 11f5595e2b..b556d7a654 100644
--- a/src/test/recovery/t/010_logical_decoding_timelines.pl
+++ b/src/test/recovery/t/010_logical_decoding_timelines.pl
@@ -66,7 +66,9 @@ $node_master->safe_psql('dropme',
 $node_master->safe_psql('postgres', 'CHECKPOINT;');
 
 my $backup_name = 'b1';
-$node_master->backup_fs_hot($backup_name);
+$node_master->stop();
+$node_master->backup_fs_cold($backup_name);
+$node_master->start();
 
 $node_master->safe_psql('postgres',
 	q[SELECT pg_create_physical_replication_slot('phys_slot');]);
-- 
2.21.0 (Apple Git-122.2)