linux-kernel - Re: [patch 1/2] mm: dont clear PG_uptodate in invalidate_complete

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Message-ID: <20080625161914.GB20236@2ka.mipt.ru>
Date:	Wed, 25 Jun 2008 20:19:15 +0400
From:	Evgeniy Polyakov <johnpol@....mipt.ru>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	jens.axboe@...cle.com, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	hugh@...itas.com, nickpiggin@...oo.com.au
Subject: Re: [patch 1/2] mm: dont clear PG_uptodate in invalidate_complete_page2()

On Wed, Jun 25, 2008 at 06:02:43PM +0200, Miklos Szeredi (miklos@...redi.hu) wrote:
> > I do not know fuse good enough, but it looks like if your patch only
> > fixes issue for pages which are in splice buffer during invalidation,
> > any subsequent call for splice() will get correct new data (at least
> > invoke readpage(s)), but in the description of error there was a
> > long timeout between reading and writing, so it was a fresh splice()
> > call, which suddenly started to return errors.
> > 
> > Is it possible that by having uptodate bit in place, but page was
> > actually freed but not removed from all trees and so on, so it
> > masked read errors? This may be not the right conclusion though :)
> 
> No, the mechanics of the problem are well understood.  Only the
> solution is problematic :)

Then why not fix filesystems to set error bit on all broken reads, if
you sure it is the case?

-- 
	Evgeniy Polyakov
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