ovl: Store lower data inode in ovl_inode

Right now ovl_inode stores inode pointer for lower inode.  This helps with
quickly getting lower inode given overlay inode (ovl_inode_lower()).

Now with metadata only copy-up, we can have metacopy inode in middle layer
as well and inode containing data can be different from ->lower.  I need to
be able to open the real file in ovl_open_realfile() and for that I need to
quickly find the lower data inode.

Hence store lower data inode also in ovl_inode.  Also provide an helper
ovl_inode_lowerdata() to access this field.

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, 4 insertions, 1 deletions

diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index ea4134e97d0d..ec237035333a 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -89,7 +89,10 @@ static inline struct ovl_entry *OVL_E(struct dentry *dentry)
 }
 
 struct ovl_inode {
-	struct ovl_dir_cache *cache;
+	union {
+		struct ovl_dir_cache *cache;	/* directory */
+		struct inode *lowerdata;	/* regular file */
+	};
 	const char *redirect;
 	u64 version;
 	unsigned long flags;