Partially revert "locks: fix file locking on overlayfs"

This partially reverts commit c568d68341be7030f5647def68851e469b21ca11.

Overlayfs files will now automatically get the correct locks, no need to
hack overlay support in VFS.

It is a partial revert, because it leaves the locks_inode() calls in place
and defines locks_inode() to file_inode().  We could revert those as well,
but it would be unnecessary code churn and it makes sense to document that
we are getting the inode for locking purposes.

Don't revert MS_NOREMOTELOCK yet since that has been part of the userspace
API for some time (though not in a useful way).  Will try to remove
internal flags later when the dust around the new mount API settles.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Acked-by: Jeff Layton <jlayton@kernel.org>
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 5bc261d..c63becc 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1456,7 +1456,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_op = &ovl_super_operations;
 	sb->s_xattr = ovl_xattr_handlers;
 	sb->s_fs_info = ofs;
-	sb->s_flags |= SB_POSIXACL | SB_NOREMOTELOCK;
+	sb->s_flags |= SB_POSIXACL;
 
 	err = -ENOMEM;
 	root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, 0));