From 1b02be21f271db6bd3cd43abb23fa596fcb6bac3 Mon Sep 17 00:00:00 2001
From: Teodor Sigaev <teodor@sigaev.ru>
Date: Mon, 27 Mar 2017 19:33:01 +0300
Subject: Fsync directory after creating or unlinking file.

If file was created/deleted just before powerloss it's possible that
file system will miss that. To prevent it, call fsync() where creating/
unlinkg file is critical.

Author: Michael Paquier
Reviewed-by: Ashutosh Bapat, Takayuki Tsunakawa, me
---
 src/backend/storage/file/fd.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

(limited to 'src/backend/storage/file/fd.c')

diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index f0ed2e9b5f4..b14979496c7 100644
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -657,6 +657,43 @@ durable_rename(const char *oldfile, const char *newfile, int elevel)
 	return 0;
 }
 
+/*
+ * durable_unlink -- remove a file in a durable manner
+ *
+ * This routine ensures that, after returning, the effect of removing file
+ * persists in case of a crash. A crash while this routine is running will
+ * leave the system in no mixed state.
+ *
+ * It does so by using fsync on the parent directory of the file after the
+ * actual removal is done.
+ *
+ * Log errors with the severity specified by caller.
+ *
+ * Returns 0 if the operation succeeded, -1 otherwise. Note that errno is not
+ * valid upon return.
+ */
+int
+durable_unlink(const char *fname, int elevel)
+{
+	if (unlink(fname) < 0)
+	{
+		ereport(elevel,
+				(errcode_for_file_access(),
+				 errmsg("could not remove file \"%s\": %m",
+						fname)));
+		return -1;
+	}
+
+	/*
+	 * To guarantee that the removal of the file is persistent, fsync
+	 * its parent directory.
+	 */
+	if (fsync_parent_path(fname, elevel) != 0)
+		return -1;
+
+	return 0;
+}
+
 /*
  * durable_link_or_rename -- rename a file in a durable manner.
  *
-- 
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