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Date: Sun, 22 Feb 2009 20:23:36 -0500
From: Theodore Tso <tytso@mit.edu>
To: Jeff Garzik <jeff@garzik.org>
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Subject: Re: vfs: Add MS_FLUSHONFSYNC mount flag
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On Sun, Feb 22, 2009 at 06:46:51PM -0500, Jeff Garzik wrote:
>
> To be more clear / precise, this means actually performing the  
> guarantees we claim to the user.  For example,
>
> fsync(2) on ext2 should trigger a storage device writeback cache flush  
> [or equivalent guarantee via FUA].
>
> fsync(2) or journal commit on ext3 should trigger a flush [or equivalent  
> guarantee via FUA].
>
> Though, certainly, the user should be able to disable this strict  
> behavior and trade correctness for performance.

No argument here.  The *default* should be that we respect fsync().
However, the user should be able to configure with a reasonable amount
of granularity tradeoffs between safety and performance and/or battery
usage.

						- Ted