[PATCH] vfs: O_* bit numbers uniqueness check fix 2

[Wu Fengguang <fengguang.wu@intel.com>]

Follow the comment by Andreas:

	It's non-obvious why there are 18 flags listed here, but the hweight
	is only 17?  Presumably this is because O_RDONLY has value 0, but that
	should at least be
	listed in a comment, or the test could be written more explicitly, like:

		  BUILD_BUG_ON(18 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(


CC: Andreas Dilger <adilger@sun.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
 fs/fcntl.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- linux-mm.orig/fs/fcntl.c	2010-03-12 21:39:01.000000000 +0800
+++ linux-mm/fs/fcntl.c	2010-03-12 21:38:42.000000000 +0800
@@ -742,7 +742,7 @@ EXPORT_SYMBOL(kill_fasync);
 static int __init fcntl_init(void)
 {
 	/* please add new bits here to ensure allocation uniqueness */
-	BUILD_BUG_ON(17 != HWEIGHT32(
+	BUILD_BUG_ON(18 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(
 		O_RDONLY	| O_WRONLY	| O_RDWR	|
 		O_CREAT		| O_EXCL	| O_NOCTTY	|
 		O_TRUNC		| O_APPEND	| O_NONBLOCK	|