ovl: do not set overlay.opaque for new directories

Enable optimizations only if user opted-in for any of extended features.
If optimization is enabled, it breaks existing use case when a lower layer
directory appears after directory was created on a merged layer. If
overlay.opaque is applied, new files on lower layer are not visible.

Consider the following scenario:
- /lower and /upper are mounted to /merged
- directory /merged/new-dir is created with a file test1
- overlay is unmounted
- directory /lower/new-dir is created with a file test2
- overlay is mounted again

If opaque is applied by default, file test2 is not going to be visible
without explicitly clearing the overlay.opaque attribute

Signed-off-by: Vyacheslav Yurkov <Vyacheslav.Yurkov@bruker.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 2584345..9154222 100644 (file)
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -321,6 +321,7 @@ static bool ovl_type_origin(struct dentry *dentry)
 static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
                            struct ovl_cattr *attr)
 {
+       struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
        struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
        struct inode *udir = upperdir->d_inode;
        struct dentry *newdentry;
@@ -339,7 +340,8 @@ static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
        if (IS_ERR(newdentry))
                goto out_unlock;
 
-       if (ovl_type_merge(dentry->d_parent) && d_is_dir(newdentry)) {
+       if (ovl_type_merge(dentry->d_parent) && d_is_dir(newdentry) &&
+           !ovl_allow_offline_changes(ofs)) {
                /* Setting opaque here is just an optimization, allow to fail */
                ovl_set_opaque(dentry, newdentry);
        }