From: John Wolfe <jwolfe@vmware.com>
Date: Thu, 8 Sep 2022 21:51:39 +0000 (-0700)
Subject: lib/file: Clarify why File_GetSize opens and closes the file.
X-Git-Tag: stable-12.2.0~119
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a2299e2022718f7fd833714a2252252c07249745;p=thirdparty%2Fopen-vm-tools.git

lib/file: Clarify why File_GetSize opens and closes the file.

Spell out what's going on.
---

diff --git a/open-vm-tools/lib/file/file.c b/open-vm-tools/lib/file/file.c
index aabe983a2..10403be27 100644
--- a/open-vm-tools/lib/file/file.c
+++ b/open-vm-tools/lib/file/file.c
@@ -1,5 +1,5 @@
 /*********************************************************
- * Copyright (C) 1998-2021 VMware, Inc. All rights reserved.
+ * Copyright (C) 1998-2022 VMware, Inc. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU Lesser General Public License as published
@@ -1499,6 +1499,14 @@ File_GetModTimeString(const char *pathName)  // IN:
  *
  *      Get size of file. Try File_GetSizeEx to get size of directory/symlink.
  *
+ *      For performance reasons, whenever a file grows, many file systems elect
+ *      to not update the on-storage inode information until close or when
+ *      forced to write a dirty page. This is done to avoid wasting I/O
+ *      throughput.
+ *
+ *      The only way to determine the exact, up-to-date size of a file is to
+ *      open it and query the file size.
+ *
  * Results:
  *      Size of file or -1.
  *