linux-kernel - Re: vfs: Add MS_FLUSHONFSYNC mount flag

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Date:	Sun, 22 Feb 2009 18:46:51 -0500
From:	Jeff Garzik <jeff@...zik.org>
To:	Theodore Tso <tytso@....edu>
CC:	Pavel Machek <pavel@....cz>, Eric Sandeen <sandeen@...hat.com>,
	Jan Kara <jack@...e.cz>,
	Fernando Luis V?zquez Cao <fernando@....ntt.co.jp>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	kernel list <linux-kernel@...r.kernel.org>,
	Jens Axboe <jens.axboe@...cle.com>, fernando@....ac.jp,
	Ric Wheeler <rwheeler@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: vfs: Add MS_FLUSHONFSYNC mount flag

Jeff Garzik wrote:
> Correctness should come before performance.  Linux has not had 
> credibility here, in the ATA+ext[23] space at least, and it is 
> embarrassing.

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.

	Jeff

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