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 36a2d623415938529983e903adf023ee286732d4..fbb97b5cf1ac2ffd999a46c529e89d882ce041b9 100644 (file)
--- a/src/bin/pg_rewind/filemap.c
+++ b/src/bin/pg_rewind/filemap.c
@@ -349,8 +349,6 @@ 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;
@@ -362,16 +360,6 @@ process_target_file(const char *path, file_type_t type, size_t oldsize,
     * the source data folder when processing the source files.
     */
 
-   snprintf(localpath, sizeof(localpath), "%s/%s", datadir_target, path);
-   if (lstat(localpath, &statbuf) < 0)
-   {
-       if (errno != ENOENT)
-           pg_fatal("could not stat file \"%s\": %m",
-                    localpath);
-
-       exists = false;
-   }
-
    if (map->array == NULL)
    {
        /* on first call, initialize lookup array */