v2-0001-skip-copydir-if-either-src-directory-or-dst-direc.patch

From 650221d14c1c34023aa66b1c22398eeae00dbcb8 Mon Sep 17 00:00:00 2001
From: Paul Guo <paulguo@gmail.com>
Date: Tue, 30 Apr 2019 13:30:49 +0800
Subject: [PATCH v2] skip copydir() if either src directory or dst directory is
 missing due to re-redoing create database but the tablespace is dropped.

---
 src/backend/access/rmgrdesc/dbasedesc.c | 14 ++++++----
 src/backend/commands/dbcommands.c       | 35 ++++++++++++++++++++++++-
 src/backend/commands/tablespace.c       | 28 +-------------------
 3 files changed, 44 insertions(+), 33 deletions(-)

diff --git a/src/backend/access/rmgrdesc/dbasedesc.c b/src/backend/access/rmgrdesc/dbasedesc.c
index c7d60ce10d..35092ffb0e 100644
--- a/src/backend/access/rmgrdesc/dbasedesc.c
+++ b/src/backend/access/rmgrdesc/dbasedesc.c
@@ -23,21 +23,25 @@ dbase_desc(StringInfo buf, XLogReaderState *record)
 {
 	char	   *rec = XLogRecGetData(record);
 	uint8		info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
+	char	   *dbpath1, *dbpath2;
 
 	if (info == XLOG_DBASE_CREATE)
 	{
 		xl_dbase_create_rec *xlrec = (xl_dbase_create_rec *) rec;
 
-		appendStringInfo(buf, "copy dir %u/%u to %u/%u",
-						 xlrec->src_tablespace_id, xlrec->src_db_id,
-						 xlrec->tablespace_id, xlrec->db_id);
+		dbpath1 = GetDatabasePath(xlrec->src_db_id,  xlrec->src_tablespace_id);
+		dbpath2 = GetDatabasePath(xlrec->db_id, xlrec->tablespace_id);
+		appendStringInfo(buf, "copy dir %s to %s", dbpath1, dbpath2);
+		pfree(dbpath2);
+		pfree(dbpath1);
 	}
 	else if (info == XLOG_DBASE_DROP)
 	{
 		xl_dbase_drop_rec *xlrec = (xl_dbase_drop_rec *) rec;
 
-		appendStringInfo(buf, "dir %u/%u",
-						 xlrec->tablespace_id, xlrec->db_id);
+		dbpath1 = GetDatabasePath(xlrec->db_id, xlrec->tablespace_id);
+		appendStringInfo(buf, "dir %s", dbpath1);
+		pfree(dbpath1);
 	}
 }
 
diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index 9707afabd9..b7943529be 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -45,6 +45,7 @@
 #include "commands/defrem.h"
 #include "commands/seclabel.h"
 #include "commands/tablespace.h"
+#include "common/file_perm.h"
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
 #include "pgstat.h"
@@ -2089,7 +2090,9 @@ dbase_redo(XLogReaderState *record)
 		xl_dbase_create_rec *xlrec = (xl_dbase_create_rec *) XLogRecGetData(record);
 		char	   *src_path;
 		char	   *dst_path;
+		char	   *parent_path;
 		struct stat st;
+		bool	    do_copydir = true;
 
 		src_path = GetDatabasePath(xlrec->src_db_id, xlrec->src_tablespace_id);
 		dst_path = GetDatabasePath(xlrec->db_id, xlrec->tablespace_id);
@@ -2107,6 +2110,35 @@ dbase_redo(XLogReaderState *record)
 						(errmsg("some useless files may be left behind in old database directory \"%s\"",
 								dst_path)));
 		}
+		else
+		{
+			/*
+			 * It is possible that the tablespace was later dropped, but we are
+			 * re-redoing database create before that. In that case,
+			 * the directory are missing, we simply skip the copydir step.
+			 */
+			parent_path = pstrdup(dst_path);
+			get_parent_directory(parent_path);
+			if (!(stat(parent_path, &st) == 0 && S_ISDIR(st.st_mode)))
+			{
+				do_copydir = false;
+				ereport(WARNING,
+						(errmsg("directory \"%s\" for copydir() does not exists."
+								"It is possibly expected. Skip copydir().",
+								parent_path)));
+			}
+			pfree(parent_path);
+		}
+
+		/* src directory is possibly missing also. See previous comment. */
+		if (!(stat(src_path, &st) == 0 && S_ISDIR(st.st_mode)))
+		{
+			do_copydir = false;
+			ereport(WARNING,
+					(errmsg("source directory \"%s\" for copydir() does not exists."
+							"It is possibly expected. Skip copydir().",
+							src_path)));
+		}
 
 		/*
 		 * Force dirty buffers out to disk, to ensure source database is
@@ -2119,7 +2151,8 @@ dbase_redo(XLogReaderState *record)
 		 *
 		 * We don't need to copy subdirectories
 		 */
-		copydir(src_path, dst_path, false);
+		if (do_copydir)
+			copydir(src_path, dst_path, false);
 	}
 	else if (info == XLOG_DBASE_DROP)
 	{
diff --git a/src/backend/commands/tablespace.c b/src/backend/commands/tablespace.c
index 8ec963f1cf..798c4586b8 100644
--- a/src/backend/commands/tablespace.c
+++ b/src/backend/commands/tablespace.c
@@ -154,8 +154,6 @@ TablespaceCreateDbspace(Oid spcNode, Oid dbNode, bool isRedo)
 				/* Directory creation failed? */
 				if (MakePGDirectory(dir) < 0)
 				{
-					char	   *parentdir;
-
 					/* Failure other than not exists or not in WAL replay? */
 					if (errno != ENOENT || !isRedo)
 						ereport(ERROR,
@@ -168,32 +166,8 @@ TablespaceCreateDbspace(Oid spcNode, Oid dbNode, bool isRedo)
 					 * continue by creating simple parent directories rather
 					 * than a symlink.
 					 */
-
-					/* create two parents up if not exist */
-					parentdir = pstrdup(dir);
-					get_parent_directory(parentdir);
-					get_parent_directory(parentdir);
-					/* Can't create parent and it doesn't already exist? */
-					if (MakePGDirectory(parentdir) < 0 && errno != EEXIST)
-						ereport(ERROR,
-								(errcode_for_file_access(),
-								 errmsg("could not create directory \"%s\": %m",
-										parentdir)));
-					pfree(parentdir);
-
-					/* create one parent up if not exist */
-					parentdir = pstrdup(dir);
-					get_parent_directory(parentdir);
-					/* Can't create parent and it doesn't already exist? */
-					if (MakePGDirectory(parentdir) < 0 && errno != EEXIST)
-						ereport(ERROR,
-								(errcode_for_file_access(),
-								 errmsg("could not create directory \"%s\": %m",
-										parentdir)));
-					pfree(parentdir);
-
 					/* Create database directory */
-					if (MakePGDirectory(dir) < 0)
+					if (pg_mkdir_p(dir, pg_dir_create_mode) < 0)
 						ereport(ERROR,
 								(errcode_for_file_access(),
 								 errmsg("could not create directory \"%s\": %m",
-- 
2.17.2