One quick question:

On Fri,  7 Oct 2011 00:11:05 -0700
Allison Henderson [off-list ref] wrote:

+	/* Secure delete any blocks still in our range */
+	if (jbd2_pblk_count > 0)
+		err = ext4_secure_delete_pblks(journal->j_inode,
+			jbd2_pblk_start, jbd2_pblk_count);
+
+out:
+	spin_unlock(&journal->j_pair_lock);

ext4_secure_delete_pblks() appears to do its job synchronously - it has
calls to things like sync_dirty_buffer() and such.  How can you do that
while holding ->j_pair_lock?

Thanks,

jon