From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeff Moyer <jmoyer@redhat.com>
Subject: Re: [RESEND][PATCH v2] block: remove plugging at buffered write time
Date: Mon, 09 Apr 2012 10:34:44 -0400
Message-ID: <x494nst7z3v.fsf@segfault.boston.devel.redhat.com>
References: <20120408010600.GA31377@localhost>
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Cc: Andrew Morton <akpm@linux-foundation.org>,
	Jens Axboe <axboe@kernel.dk>, linux-fsdevel@vger.kernel.org,
	LKML <linux-kernel@vger.kernel.org>,
	Dave Chinner <david@fromorbit.com>,
	Christoph Hellwig <hch@infradead.org>, Jan Kara <jack@suse.cz>,
	Chris Mason <chris.mason@oracle.com>,
	Shaohua Li <shli@fusionio.com>
To: Wu Fengguang <fengguang.wu@intel.com>
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In-Reply-To: <20120408010600.GA31377@localhost> (Wu Fengguang's message of
	"Sun, 8 Apr 2012 09:06:00 +0800")
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Wu Fengguang <fengguang.wu@intel.com> writes:

> Buffered write(2) is not directly tied to IO, so it's not suitable to
> handle plug in generic_file_aio_write().
[snip, moved]
> Note that plugging for O_SYNC writes is also removed. The user may pass
> arbitrary @size arguments, which may be much larger than the preferable
> I/O size, or may cross extent/device boundaries. Let the lower layers
> handle the plugging. Otherwise the plugging code here will turn the
> low level plugging into no-ops.

I assume you have some numbers to back this up, right?  Care to share
those?

> Also moves unplugging for direct I/O from around ->direct_IO() down to
> do_blockdev_direct_IO().

This could be handled in a separate patch.  Acked-by: Jeff Moyer
<jmoyer@redhat.com> for this part.

Cheers,
Jeff