From 2d8dd38a5aa0cc2490bbad9b75e77fa154e1d145 Mon Sep 17 00:00:00 2001
From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Date: Thu, 6 Aug 2009 15:07:39 -0700
Subject: [PATCH] vfs: mnt_want_write_file(): fix special file handling

I suspect that mnt_want_write_file() may have wrong assumption.  I think
mnt_want_write_file() is assuming it increments ->mnt_writers if
(file->f_mode & FMODE_WRITE).  But, if it's special_file(), it is false?

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Acked-by: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 fs/namespace.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index 277c28a63ea..7230787d18b 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -316,7 +316,8 @@ EXPORT_SYMBOL_GPL(mnt_clone_write);
  */
 int mnt_want_write_file(struct file *file)
 {
-	if (!(file->f_mode & FMODE_WRITE))
+	struct inode *inode = file->f_dentry->d_inode;
+	if (!(file->f_mode & FMODE_WRITE) || special_file(inode->i_mode))
 		return mnt_want_write(file->f_path.mnt);
 	else
 		return mnt_clone_write(file->f_path.mnt);
-- 
2.32.0.93.g670b81a890