ovl: Initialize ovl_inode->redirect in ovl_get_inode()

ovl_inode->redirect is an inode property and should be initialized in
ovl_get_inode() only when we are adding a new inode to cache.  If inode is
already in cache, it is already initialized and we should not be touching
ovl_inode->redirect field.

As of now this is not a problem as redirects are used only for directories
which don't share inode.  But soon I want to use redirects for regular
files also and there it can become an issue.

Hence, move ->redirect initialization in ovl_get_inode().

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

fs/overlayfs/inode.c

@@ -844,6 +844,7 @@ struct inode *ovl_get_inode(struct super_block *sb,
 			}
 
 			dput(upperdentry);
+			kfree(oip->redirect);
 			goto out;
 		}
 
@@ -867,6 +868,8 @@ struct inode *ovl_get_inode(struct super_block *sb,
 	if (oip->index)
 		ovl_set_flag(OVL_INDEX, inode);
 
+	OVL_I(inode)->redirect = oip->redirect;
+
 	/* Check for non-merge dir that may have whiteouts */
 	if (is_dir) {
 		if (((upperdentry && lowerdentry) || oip->numlower > 1) ||

fs/overlayfs/namei.c

@@ -1009,19 +1009,13 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 			.lowerpath = stack,
 			.index = index,
 			.numlower = ctr,
+			.redirect = upperredirect,
 		};
 
 		inode = ovl_get_inode(dentry->d_sb, &oip);
 		err = PTR_ERR(inode);
 		if (IS_ERR(inode))
 			goto out_free_oe;
-
-		/*
-		 * NB: handle redirected hard links when non-dir redirects
-		 * become possible
-		 */
-		WARN_ON(OVL_I(inode)->redirect);
-		OVL_I(inode)->redirect = upperredirect;
 	}
 
 	revert_creds(old_cred);

fs/overlayfs/overlayfs.h

@@ -335,6 +335,7 @@ struct ovl_inode_params {
 	struct ovl_path *lowerpath;
 	struct dentry *index;
 	unsigned int numlower;
+	char *redirect;
 };
 struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev);
 struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,