From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 6 Sep 2020 15:50:41 +0000 (-0400)
Subject: Remove useless lstat() call in pg_rewind.
X-Git-Tag: REL9_5_24~60
X-Git-Url: http://git.postgresql.org/gitweb/?a=commitdiff_plain;h=be6667081e233d5868dd7e59ca2226348a489fb5;p=postgresql.git

Remove useless lstat() call in pg_rewind.

This is duplicative of an lstat that was just done by the calling
function (traverse_datadir), besides which we weren't really doing
anything with the results.  There's not much point in checking to
see if someone removed the file since the previous lstat, since the
FILE_ACTION_REMOVE code would have to deal with missing-file cases
anyway.  Moreover, the "exists = false" assignment was a dead store;
nothing was done with that value later.

A syscall saved is a syscall earned, so back-patch to 9.5
where this code was introduced.

Discussion: https://postgr.es/m/1221796.1599329320@sss.pgh.pa.us
---

diff --git a/src/bin/pg_rewind/filemap.c b/src/bin/pg_rewind/filemap.c
index 366b97de91f..f1190b6287b 100644
--- a/src/bin/pg_rewind/filemap.c
+++ b/src/bin/pg_rewind/filemap.c
@@ -254,23 +254,11 @@ process_target_file(const char *path, file_type_t type, size_t oldsize,
 					const char *link_target)
 {
 	bool		exists;
-	char		localpath[MAXPGPATH];
-	struct stat statbuf;
 	file_entry_t key;
 	file_entry_t *key_ptr;
 	filemap_t  *map = filemap;
 	file_entry_t *entry;
 
-	snprintf(localpath, sizeof(localpath), "%s/%s", datadir_target, path);
-	if (lstat(localpath, &statbuf) < 0)
-	{
-		if (errno != ENOENT)
-			pg_fatal("could not stat file \"%s\": %s\n",
-					 localpath, strerror(errno));
-
-		exists = false;
-	}
-
 	if (map->array == NULL)
 	{
 		/* on first call, initialize lookup array */