fix_do_pg_abort_backup_v9.patch

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e729180..f547c0e 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -10636,8 +10636,14 @@ do_pg_start_backup(const char *backupidstr, bool fast, TimeLineID *starttli_p,
 	{
 		WALInsertLockAcquireExclusive();
 		XLogCtl->Insert.exclusiveBackupState = EXCLUSIVE_BACKUP_IN_PROGRESS;
-		WALInsertLockRelease();
+
+		/*
+		 * Set session-level lock. To avoid calling CHECK_FOR_INTERRUPTS by
+		 * LWLockReleaseClearVar before changing the backup state we change
+		 * it while holding the WAL insert lock.
+		 */
 		sessionBackupState = SESSION_BACKUP_EXCLUSIVE;
+		WALInsertLockRelease();
 	}
 	else
 		sessionBackupState = SESSION_BACKUP_NON_EXCLUSIVE;
@@ -10865,11 +10871,18 @@ do_pg_stop_backup(char *labelfile, bool waitforarchive, TimeLineID *stoptli_p)
 	{
 		XLogCtl->Insert.forcePageWrites = false;
 	}
-	WALInsertLockRelease();
 
-	/* Clean up session-level lock */
+	/*
+	 * Clean up session-level lock. To avoid calling CHECK_FOR_INTERRUPTS by
+	 * LWLockReleaseClearVar before changing the backup state we change it
+	 * while holding the WAL insert lock as this allows to keep backup counters
+	 * kept in shared memory consistent with the state of the session starting
+	 * or stopping a backup.
+	 */
 	sessionBackupState = SESSION_BACKUP_NONE;
 
+	WALInsertLockRelease();
+
 	/*
 	 * Read and parse the START WAL LOCATION line (this code is pretty crude,
 	 * but we are not expecting any variability in the file format).
@@ -11107,8 +11120,16 @@ do_pg_stop_backup(char *labelfile, bool waitforarchive, TimeLineID *stoptli_p)
 void
 do_pg_abort_backup(void)
 {
+	/*
+	 * Quick exit if session is not keeping around a non-exclusive backup
+	 * already started.
+	 */
+	if (sessionBackupState == SESSION_BACKUP_NONE)
+		return;
+
 	WALInsertLockAcquireExclusive();
 	Assert(XLogCtl->Insert.nonExclusiveBackups > 0);
+	Assert(sessionBackupState == SESSION_BACKUP_NON_EXCLUSIVE);
 	XLogCtl->Insert.nonExclusiveBackups--;
 
 	if (XLogCtl->Insert.exclusiveBackupState == EXCLUSIVE_BACKUP_NONE &&
diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
index cbcb3db..9598b53 100644
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -214,8 +214,8 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
 	/*
 	 * Once do_pg_start_backup has been called, ensure that any failure causes
 	 * us to abort the backup so we don't "leak" a backup counter. For this
-	 * reason, *all* functionality between do_pg_start_backup() and
-	 * do_pg_stop_backup() should be inside the error cleanup block!
+	 * reason, *all* functionality between do_pg_start_backup() until
+	 * do_pg_stop_backup() is done should be inside the error cleanup block!
 	 */
 
 	PG_ENSURE_ERROR_CLEANUP(base_backup_cleanup, (Datum) 0);
@@ -324,10 +324,16 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
 			else
 				pq_putemptymessage('c');	/* CopyDone */
 		}
+
+		/*
+		 * Finish the backup while still holding the cleanup callback to
+		 * avoid inconsistent in-memory data should the this call fail
+		 * before sessionBackupState is updated.
+		 */
+		endptr = do_pg_stop_backup(labelfile->data, !opt->nowait, &endtli);
 	}
 	PG_END_ENSURE_ERROR_CLEANUP(base_backup_cleanup, (Datum) 0);
 
-	endptr = do_pg_stop_backup(labelfile->data, !opt->nowait, &endtli);
 
 	if (opt->includewal)
 	{