linux-kernel - Re: [PATCH] aio: propogate post-EIOCBQUEUED errors to completion event

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Message-ID: <20070220161948.GQ6133@think.oraclecorp.com>
Date:	Tue, 20 Feb 2007 11:19:48 -0500
From:	Chris Mason <chris.mason@...cle.com>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	Trond Myklebust <trond.myklebust@....uio.no>,
	Benjamin LaHaise <bcrl@...ck.org>,
	"Ananiev, Leonid I" <leonid.i.ananiev@...el.com>,
	Zach Brown <zach.brown@...cle.com>, linux-aio@...ck.org,
	linux-kernel@...r.kernel.org,
	Suparna bhattacharya <suparna@...ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] aio: propogate post-EIOCBQUEUED errors to completion event

On Tue, Feb 20, 2007 at 05:06:47PM +0100, Arjan van de Ven wrote:
> > We don't try to resolve "conflicting" writes between ordinary mmap() and
> > write(), so why should we be doing it for mmap and O_DIRECT?
> > 
> > mmap() is designed to violate the ordinary mutex locks for write(), so
> > if a conflict arises, whether it be with O_DIRECT or ordinary writes
> > then it is a case of "last writer wins".
> 
> but.. wouldn't an O_DIRECT *read* even cause this?

The O_DIRECT read is fine because it doesn't leave bad data in the page
cache.  The point of doing invalidate_inode_pages2_range is to purge
page cache data that has the old contents of the file before the
O_DIRECT write.

-chris

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