afs: Get the target vnode in afs_rmdir() and get a callback on it

Get the target vnode in afs_rmdir() and validate it before we attempt the
deletion, The vnode pointer will be passed through to the delivery function
in a later patch so that the delivery function can mark it deleted.
Signed-off-by: David Howells <dhowells@redhat.com>

fs/afs/dir.c

@@ -1174,7 +1174,7 @@ static void afs_dir_remove_subdir(struct dentry *dentry)
 static int afs_rmdir(struct inode *dir, struct dentry *dentry)
 {
 	struct afs_fs_cursor fc;
-	struct afs_vnode *dvnode = AFS_FS_I(dir);
+	struct afs_vnode *dvnode = AFS_FS_I(dir), *vnode = NULL;
 	struct key *key;
 	u64 data_version = dvnode->status.data_version;
 	int ret;
@@ -1188,6 +1188,14 @@ static int afs_rmdir(struct inode *dir, struct dentry *dentry)
 		goto error;
 	}
 
+	/* Try to make sure we have a callback promise on the victim. */
+	if (d_really_is_positive(dentry)) {
+		vnode = AFS_FS_I(d_inode(dentry));
+		ret = afs_validate(vnode, key);
+		if (ret < 0)
+			goto error_key;
+	}
+
 	ret = -ERESTARTSYS;
 	if (afs_begin_vnode_operation(&fc, dvnode, key)) {
 		while (afs_select_fileserver(&fc)) {
@@ -1206,6 +1214,7 @@ static int afs_rmdir(struct inode *dir, struct dentry *dentry)
 		}
 	}
 
+error_key:
 	key_put(key);
 error:
 	return ret;