From: Jan Kara Subject: Re: [PATCH v2] Adding support to freeze and unfreeze a journal Date: Mon, 9 May 2011 11:53:13 +0200 Message-ID: <20110509095313.GB4122@quack.suse.cz> References: <1304798662-3884-1-git-send-email-surbhi.palande@canonical.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: adilger.kernel@dilger.ca, jack@suse.cz, toshi.okajima@jp.fujitsu.com, tytso@mit.edu, m.mizuma@jp.fujitsu.com, linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, sandeen@redhat.com To: Surbhi Palande Return-path: Received: from cantor2.suse.de ([195.135.220.15]:50190 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750736Ab1EIJxQ (ORCPT ); Mon, 9 May 2011 05:53:16 -0400 Content-Disposition: inline In-Reply-To: <1304798662-3884-1-git-send-email-surbhi.palande@canonical.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Sat 07-05-11 23:04:22, Surbhi Palande wrote: > +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. > + wake_up(&journal->j_wait_frozen); > +} > +EXPORT_SYMBOL(jbd2_journal_thaw); Honza -- Jan Kara SUSE Labs, CR