Date: Fri, 22 Apr 2011 22:34:34 +0200
From: Jan Kara <jack@suse.cz>
To: Chris Mason <chris.mason@oracle.com>
Cc: djwong <djwong@us.ibm.com>, Mingming Cao <cmm@us.ibm.com>,
        Christoph Hellwig <hch@infradead.org>,
        Jeff Layton <jlayton@redhat.com>, Jan Kara <jack@suse.cz>,
        Dave Chinner <david@fromorbit.com>, Joel Becker <jlbec@evilplan.org>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Jens Axboe <axboe@kernel.dk>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Mingming Cao <mcao@us.ibm.com>,
        linux-scsi <linux-scsi@vger.kernel.org>,
        Dave Hansen <dave@linux.vnet.ibm.com>
Subject: Re: [RFC v2] block integrity: Stabilize(?) pages during writeback
Message-ID: <20110422203434.GA2977@quack.suse.cz>
References: <20110406232938.GF1110@tux1.beaverton.ibm.com>
 <20110407165700.GB7363@quack.suse.cz>
 <20110408203135.GH1110@tux1.beaverton.ibm.com>
 <20110411124229.47bc28f6@corrin.poochiereds.net>
 <1302543595-sup-4352@think>
 <1302569212.2580.13.camel@mingming-laptop>
 <20110412005719.GA23077@infradead.org>
 <1302742128.2586.274.camel@mingming-laptop>
 <20110422000226.GA22189@tux1.beaverton.ibm.com>
 <1303476503-sup-4141@think>
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On Fri 22-04-11 08:50:01, Chris Mason wrote:
> Excerpts from Darrick J. Wong's message of 2011-04-21 20:02:26 -0400:
> > Hi everyone,
> > 
> > I've finally managed to get together a patch that seems to provide stable pages
> > during writeback, or at least gets us to the point that after several days of
> > running tests I don't see DIF checksum errors anymore. :)
> > 
> > The last two pieces to go into this puzzle were (a) bio_integrity_prep needs to
> > walk the process tree to find all userland ptes that map to a particular memory
> > page and revoke write access, and
> 
> Hmm, did you need the bio_integrity_prep change for all the filesystems?
> This should be happening already as part of using page_mkwrite.
  Or more precisely page_mkclean() should do what you try to do in
bio_integrity_prep()... It would certainly be interesting (bug) if you
could write to the page after calling page_mkclean() without page_mkwrite()
being called.

									Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR
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