ovl: fix may_write_real() for overlayfs directories

Overlayfs directory file_inode() is the overlay inode whether the real
inode is upper or lower.

This fixes a regression in xfstest generic/158.

Fixes: 7c6893e3c9ab ("ovl: don't allow writing ioctl on lower layer")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index 54059b142d6b..3b601f115b6c 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -468,7 +468,9 @@ static inline int may_write_real(struct file *file)
 
         /* File refers to upper, writable layer? */
         upperdentry = d_real(dentry, NULL, 0, D_REAL_UPPER);
-        if (upperdentry && file_inode(file) == d_inode(upperdentry))
+        if (upperdentry &&
+            (file_inode(file) == d_inode(upperdentry) ||
+             file_inode(file) == d_inode(dentry)))
                 return 0;
 
         /* Lower layer: can't write to real file, sorry... */