From: Jan Kara Subject: Re: [PATCH v2 6/7] VFS: Document s_frozen state through freeze_super Date: Fri, 6 Jan 2012 01:36:04 +0100 Message-ID: <20120106003604.GD3790@quack.suse.cz> References: <1323367477-21685-1-git-send-email-kamal@canonical.com> <1323367477-21685-7-git-send-email-kamal@canonical.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jan Kara , Alexander Viro , Andreas Dilger , Matthew Wilcox , Randy Dunlap , Theodore Tso , linux-doc@vger.kernel.org, linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Surbhi Palande , Valerie Aurora , Christopher Chaltain , "Peter M. Petrakis" , Mikulas Patocka To: Kamal Mostafa Return-path: Received: from cantor2.suse.de ([195.135.220.15]:41891 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964847Ab2AFAgG (ORCPT ); Thu, 5 Jan 2012 19:36:06 -0500 Content-Disposition: inline In-Reply-To: <1323367477-21685-7-git-send-email-kamal@canonical.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu 08-12-11 10:04:36, Kamal Mostafa wrote: > From: Valerie Aurora Looks good. You can add: Acked-by: Jan Kara Honza > BugLink: https://bugs.launchpad.net/bugs/897421 > Signed-off-by: Valerie Aurora > Cc: Kamal Mostafa > Tested-by: Peter M. Petrakis > [kamal@canonical.com: patch restructure] > Signed-off-by: Kamal Mostafa > --- > fs/super.c | 18 ++++++++++++++++++ > 1 files changed, 18 insertions(+), 0 deletions(-) > > diff --git a/fs/super.c b/fs/super.c > index 5629d06..a56696b 100644 > --- a/fs/super.c > +++ b/fs/super.c > @@ -1140,6 +1140,24 @@ out: > * Syncs the super to make sure the filesystem is consistent and calls the fs's > * freeze_fs. Subsequent calls to this without first thawing the fs will return > * -EBUSY. > + * > + * During this function, sb->s_frozen goes through these values: > + * > + * SB_UNFROZEN: File system is normal, all writes progress as usual. > + * > + * SB_FREEZE_WRITE: The file system is in the process of being frozen > + * and any remaining out-standing writes are being synced. Writes > + * that complete in-process writes should be permitted but new ones > + * should be blocked. > + * > + * SB_FREEZE_TRANS: The file system is frozen. The ->freeze_fs and > + * ->unfreeze_fs ops are the only operations permitted to write to the > + * file system in this state. > + * > + * sb->s_frozen is protected by sb->s_umount. Additionally, > + * SB_FREEZE_WRITE is only temporarily set during freeze/thaw while > + * holding sb->s_umount for writing, so any other callers holding > + * sb->s_umount will never see this state. > */ > int freeze_super(struct super_block *sb) > { > -- > 1.7.5.4 > -- Jan Kara SUSE Labs, CR