On 05/09/2011 12:53 PM, Jan Kara wrote:

On Sat 07-05-11 23:04:22, Surbhi Palande wrote:

quoted

+void jbd2_journal_thaw(journal_t * journal)
+{
+	write_lock(&journal->j_state_lock);
+	journal->j_flags = journal->j_flags&= ~JBD2_FROZEN;
+	write_unlock(&journal->j_state_lock);
+	smp_wmb();

   Why is here the smp_wmb()? The write is inside a rw-lock so it cannot be
reordered. Also wake_up() is protected by queue->lock so I don't see the
need for a barrier.

Ok, thanks for letting me know. I was under the impression that a 
reorder was possible in case of SMP. I will rewrite the patch with this 
change and the one that Marco Stornelli suggested as well.

Thanks a lot!

Warm Regards,
Surbhi.

quoted

+	wake_up(&journal->j_wait_frozen);
+}
+EXPORT_SYMBOL(jbd2_journal_thaw);

								Honza