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Date: Thu, 16 Mar 2006 19:44:29 -0500
From: "Theodore Ts'o" <tytso@mit.edu>
To: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Jan Kara <jack@suse.cz>, Andrew Morton <akpm@osdl.org>, sct@redhat.com,
       lkml <linux-kernel@vger.kernel.org>,
       linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: ext3_ordered_writepage() questions
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On Thu, Mar 16, 2006 at 03:45:21PM -0800, Badari Pulavarty wrote:
> Yep. I wasn't expecting to see buffers in the transaction/log. I was
> expecting to see some "dummy" transaction - which these buffers are
> attached to provide ordering. (even though we are not doing metadata
> updates). In fact, I was expecting to see "ctime" update in the
> transaction.

What you're missing is that journal_start() and journal_stop() don't
create a transaction.  They delimit an operation, yes, but multiple
operations are grouped together to form a transaction.  Transactions
are only closed when after the commit_internal or if the journal runs
out of space.  So you're not going to see a dummy transaction which
the buffers are attached to; instead, all of the various operations
happening within commit_interval are grouped into a single transaction.

This is all explained in Stephen's paper; see page #4 in:

http://ftp.kernel.org/pub/linux/kernel/people/sct/ext3/journal-design.ps.gz

						- Ted
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