[PATCH] ovl: clarify dget/dput in ovl_cleanup()

[Miklos Szeredi <mszeredi@redhat.com>]

Add a comment explaining the reason for the seemingly pointless extra
reference.

Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
 fs/overlayfs/dir.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index ab65e98a1def..9e97f7dffd90 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -28,6 +28,10 @@ int ovl_cleanup(struct ovl_fs *ofs, struct inode *wdir, struct dentry *wdentry)
 {
 	int err;
 
+	/*
+	 * Cached negative upper dentries are generally not useful, so grab a
+	 * ref to the victim to keep it from turning negative.
+	 */
 	dget(wdentry);
 	if (d_is_dir(wdentry))
 		err = ovl_do_rmdir(ofs, wdir, wdentry);
-- 
2.47.0