From: Andreas Dilger <adilger@sun.com>
Subject: Re: barriers off by default?
Date: Thu, 15 May 2008 09:21:35 -0700
Message-ID: <20080515162135.GB3098@webber.adilger.int>
References: <482868A5.1000102@redhat.com>
 <20080515144355.GB19325@atrey.karlin.mff.cuni.cz> <482C5E14.9030004@redhat.com>
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Cc: ext4 development <linux-ext4@vger.kernel.org>,
	Jan Kara <jack@suse.cz>
To: Eric Sandeen <sandeen@redhat.com>
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On May 15, 2008  11:00 -0500, Eric Sandeen wrote:
> ... the fsync change seems sane too...
> 
> @@ -85,7 +86,10 @@ int ext3_sync_file(struct file * file, s
>                         .sync_mode = WB_SYNC_ALL,
>                         .nr_to_write = 0, /* sys_fsync did this */
>                 };
> +               journal_t *journal = EXT3_SB(inode->i_sb)->s_journal;
>                 ret = sync_inode(inode, &wbc);
> +               if (journal && (journal->j_flags & JFS_BARRIER))
> +                       blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
>         }
>  out:
> 
> I assume we need that for some power-plug-pull scenarios ... in fact I
> had just been meaning to do something similar after reading an old
> thread on barriers.  reiserfs & xfs do this already in their sync paths.

Wouldn't it make more sense to add this into the generic do_fsync()
routine?

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.