linux-kernel - [RFC PATCH 20/35] vfs: don't open real

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Date:   Thu, 12 Apr 2018 17:08:11 +0200
From:   Miklos Szeredi <mszeredi@...hat.com>
To:     linux-unionfs@...r.kernel.org
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [RFC PATCH 20/35] vfs: don't open real

Let overlayfs do its thing when opening a file.

This enables stacking and fixes the corner case when a file is opened for
read, modified through a writable open, and data is read from the read-only
file.  After this patch the read-only open will not return stale data even
in this case.

Signed-off-by: Miklos Szeredi <mszeredi@...hat.com>
---
 fs/open.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/fs/open.c b/fs/open.c
index d509705d5740..1d1a52908b0f 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -857,13 +857,8 @@ EXPORT_SYMBOL(file_path);
 int vfs_open(const struct path *path, struct file *file,
 	     const struct cred *cred)
 {
-	struct dentry *dentry = d_real(path->dentry, NULL, file->f_flags, 0);
-
-	if (IS_ERR(dentry))
-		return PTR_ERR(dentry);
-
 	file->f_path = *path;
-	return do_dentry_open(file, d_backing_inode(dentry), NULL, cred);
+	return do_dentry_open(file, d_backing_inode(path->dentry), NULL, cred);
 }
 
 struct file *path_open(const struct path *path, int flags, struct inode *inode,
-- 
2.14.3