ext4: fix assertion in ext4_add_complete_io()

It doesn't make sense to require io_end->handle when we are in
nojournal mode. So update the assertion accordingly to avoid false
warnings from ext4_add_complete_io().
Reported-by: NEric Whitney <enwlinux@gmail.com>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/page-io.c

@@ -197,14 +197,15 @@ static void dump_completed_IO(struct inode *inode, struct list_head *head)
 static void ext4_add_complete_io(ext4_io_end_t *io_end)
 {
 	struct ext4_inode_info *ei = EXT4_I(io_end->inode);
+	struct ext4_sb_info *sbi = EXT4_SB(io_end->inode->i_sb);
 	struct workqueue_struct *wq;
 	unsigned long flags;
 
 	/* Only reserved conversions from writeback should enter here */
 	WARN_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
-	WARN_ON(!io_end->handle);
+	WARN_ON(!io_end->handle && sbi->s_journal);
 	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
-	wq = EXT4_SB(io_end->inode->i_sb)->rsv_conversion_wq;
+	wq = sbi->rsv_conversion_wq;
 	if (list_empty(&ei->i_rsv_conversion_list))
 		queue_work(wq, &ei->i_rsv_conversion_work);
 	list_add_tail(&io_end->list, &ei->i_rsv_conversion_list);