ovl: fix open in stacked overlay

If two overlayfs filesystems are stacked on top of each other, then we need
recursion in ovl_d_select_inode().

I guess d_backing_inode() is supposed to do that.  But currently it doesn't
and that functionality is open coded in vfs_open().  This is now copied
into ovl_d_select_inode() to fix this regression.

Reported-by: Alban Crequy <alban.crequy@gmail.com>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay...")
Cc: David Howells <dhowells@redhat.com>
Cc: <stable@vger.kernel.org> # v4.2+
Orabug: 26401569

(backport upstream commit 1c8a47df36d72ace8cf78eb6c228aa0f8027d3c2)

Signed-off-by: Shan Hai <shan.hai@oracle.com>
Reviewed-by: Somasundaram Krishnasamy <somasundaram.krishnasamy@oracle.com>

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 9934bd993e786a5e972bfad0372b4d4554e5a092..9d41fc376bc9d9d6663de8e486403dd4c33bd163 100644 (file)
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -404,6 +404,9 @@ struct inode *ovl_d_select_inode(struct dentry *dentry, unsigned file_flags)
                ovl_path_upper(dentry, &realpath);
        }
 
+       if (realpath.dentry->d_flags & DCACHE_OP_SELECT_INODE)
+               return realpath.dentry->d_op->d_select_inode(realpath.dentry, file_flags);
+
        return d_backing_inode(realpath.dentry);
 }