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From: Zach Brown <zach.brown@oracle.com>
To: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Chris Mason <chris.mason@oracle.com>,
	Benjamin LaHaise <bcrl@kvack.org>,
	"Ananiev, Leonid I" <leonid.i.ananiev@intel.com>,
	linux-aio@kvack.org, linux-kernel@vger.kernel.org,
	Suparna bhattacharya <suparna@in.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] aio: propogate post-EIOCBQUEUED errors to completion event
Date: Tue, 20 Feb 2007 10:40:03 -0800	[thread overview]
Message-ID: <528148DD-0533-4D82-A242-25A4C5D1A977@oracle.com> (raw)
In-Reply-To: <1171988988.6271.26.camel@heimdal.trondhjem.org>

>> There are some strange O_DIRECT corner cases in here such that the  
>> 'last
>> writer' may actually be a 'last reader' and winning can mean have  
>> a copy
>> of the page in page cache older than the copy on disk.
>
> As long as it is marked dirty so that it eventually gets synced to  
> disk,
> it shouldn't matter.

No, Chris is pointing out that an an O_DIRECT write can leave clean  
read pages in the page cache.

All it takes is giving a source buffer for the write which is an mmap 
()ed apeture of the region that is being written to.  If you get the  
offsets right you can get the get_user_pages() down in fs/direct-io.c  
will populate the page cache before the actual O_DIRECT write gets to  
it.

- z

  parent reply	other threads:[~2007-02-20 18:41 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-19 20:35 [PATCH] aio: propogate post-EIOCBQUEUED errors to completion event Zach Brown
2007-02-19 20:47 ` Benjamin LaHaise
2007-02-19 21:07   ` Zach Brown
2007-02-19 20:58 ` Ananiev, Leonid I
2007-02-19 21:50   ` Chris Mason
2007-02-20  0:21     ` Benjamin LaHaise
2007-02-20  0:26       ` Zach Brown
2007-02-20  0:28       ` Chris Mason
2007-02-20 16:01       ` Trond Myklebust
2007-02-20 16:06         ` Benjamin LaHaise
2007-02-20 16:06         ` Arjan van de Ven
2007-02-20 16:19           ` Chris Mason
2007-02-20 16:08         ` Chris Mason
2007-02-20 16:29           ` Trond Myklebust
2007-02-20 16:38             ` Trond Myklebust
2007-02-20 18:40             ` Zach Brown [this message]
2007-02-21  0:05               ` Trond Myklebust
2007-02-20 14:08 ` Ananiev, Leonid I

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