ext4: Always set dx_node's fake_dirent explicitly.

When ext4_dx_add_entry() has to split an index node, it has to ensure that
name_len of dx_node's fake_dirent is also zero, because otherwise e2fsck
won't recognise it as an intermediate htree node and consider the htree to
be corrupted.
Signed-off-by: NAndreas Schlick <schlick@lavabit.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/namei.c

@@ -1597,9 +1597,9 @@ static int ext4_dx_add_entry(handle_t *handle, struct dentry *dentry,
 			goto cleanup;
 		node2 = (struct dx_node *)(bh2->b_data);
 		entries2 = node2->entries;
+		memset(&node2->fake, 0, sizeof(struct fake_dirent));
 		node2->fake.rec_len = ext4_rec_len_to_disk(sb->s_blocksize,
 							   sb->s_blocksize);
-		node2->fake.inode = 0;
 		BUFFER_TRACE(frame->bh, "get_write_access");
 		err = ext4_journal_get_write_access(handle, frame->bh);
 		if (err)