A disk generated some I/O error, after it, I hitted
J_ASSERT(transaction->t_updates > 0) in journal_stop().
It seems to happened on ext3_truncate() path from stack trace. Then,
maybe the following case may trigger J_ASSERT(transaction->t_updates > 0).
ext3_truncate()
    -> ext3_free_branches()
        -> ext3_journal_test_restart()
	    -> ext3_journal_restart()
                -> journal_restart()
                transaction->t_updates--;
                /* another process aborted journal */
                    -> start_this_handle()
		    returns -EROFS without transaction->t_updates++;
    -> ext3_journal_stop()
        -> journal_stop()
	J_ASSERT(transaction->t_updates > 0)
If journal was aborted in middle of journal_restart(), ext3_truncate()
may trigger J_ASSERT().
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
        int old_handle_count, err;
        pid_t pid;
 
-       J_ASSERT(transaction->t_updates > 0);
        J_ASSERT(journal_current_handle() == handle);
 
        if (is_handle_aborted(handle))
                err = -EIO;
-       else
+       else {
+               J_ASSERT(transaction->t_updates > 0);
                err = 0;
+       }
 
        if (--handle->h_ref > 0) {
                jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
 
        int old_handle_count, err;
        pid_t pid;
 
-       J_ASSERT(transaction->t_updates > 0);
        J_ASSERT(journal_current_handle() == handle);
 
        if (is_handle_aborted(handle))
                err = -EIO;
-       else
+       else {
+               J_ASSERT(transaction->t_updates > 0);
                err = 0;
+       }
 
        if (--handle->h_ref > 0) {
                jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,