linux-ext4 - Re: [PATCH] Make non-journal fsync work properly.

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Message-ID: <20090910065747.GC8690@skywalker.linux.vnet.ibm.com>
Date:	Thu, 10 Sep 2009 12:27:47 +0530
From:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:	Frank Mayhar <fmayhar@...gle.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH] Make non-journal fsync work properly.

On Fri, Sep 04, 2009 at 07:55:00PM -0700, Frank Mayhar wrote:
> Teach ext4_write_inode() and ext4_do_update_inode() about non-journal
> mode:  If we're not using a journal, ext4_write_inode() now calls
> ext4_do_update_inode() (after getting the iloc via ext4_get_inode_loc())
> with a new "do_sync" parameter.  If that parameter is nonzero
> ext4_do_update_inode() calls sync_dirty_buffer() instead of
> ext4_handle_dirty_metadata().
> 
> This problem was found in power-fail testing, checking the amount of
> loss of files and blocks after a power failure when using fsync() and
> when not using fsync().  It turned out that using fsync() was actually
> worse than not doing so, possibly because it increased the likelihood
> that the inodes would remain unflushed and would therefore be lost at
> the power failure.
> 

I think this is related to the other thread discussing the extent leak
with non journal mode. I don't find ext4 without journal adding meta
data blocks to the inode's address space mapping private_list. That 
would mean sync_mapping_buffers -> fsync_buffers_list won't sync 
the related metadata blocks.Tell me what i am missing 

-aneesh
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