ovl: Copy up meta inode data from lowest data inode

So far lower could not be a meta inode.  So whenever it was time to copy up
data of a meta inode, we could copy it up from top most lower dentry.

But now lower itself can be a metacopy inode.  That means data copy up
needs to take place from a data inode in metacopy inode chain.  Find lower
data inode in the chain and use that for data copy up.

Introduced a helper called ovl_path_lowerdata() to find the lower data
inode chain.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index ab9a8fae0f99..32ff67fa0bfb 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -164,6 +164,18 @@ void ovl_path_lower(struct dentry *dentry, struct path *path)
         }
 }
 
+void ovl_path_lowerdata(struct dentry *dentry, struct path *path)
+{
+        struct ovl_entry *oe = dentry->d_fsdata;
+
+        if (oe->numlower) {
+                path->mnt = oe->lowerstack[oe->numlower - 1].layer->mnt;
+                path->dentry = oe->lowerstack[oe->numlower - 1].dentry;
+        } else {
+                *path = (struct path) { };
+        }
+}
+
 enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
 {
         enum ovl_path_type type = ovl_path_type(dentry);