linux-ext4 - Re: [RFC][PATCH] ext3: don't read inode block if the buffer has a write error

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Message-Id: <200806232236.30961.nickpiggin@yahoo.com.au>
Date:	Mon, 23 Jun 2008 22:36:30 +1000
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	Jan Kara <jack@...e.cz>
Cc:	Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>,
	akpm@...ux-foundation.org, sct@...hat.com, adilger@....com,
	linux-kernel@...r.kernel.org, linux-ext4@...r.kernel.org,
	sugita <yumiko.sugita.yf@...achi.com>,
	Satoshi OSHIMA <satoshi.oshima.fk@...achi.com>
Subject: Re: [RFC][PATCH] ext3: don't read inode block if the buffer has a write error

On Monday 23 June 2008 22:31, Jan Kara wrote:
> On Mon 23-06-08 21:46:27, Nick Piggin wrote:

> > I don't know why it was done like this, or if anybody actually tested
> > any of it, but AFAIKS the best way to fix this is to simply not
> > clear any uptodate bits upon write errors.
>
>   That would be non-trivial effort because there are lots of places which
> do things like:
>   wait_on_buffer(bh);
>   if (!buffer_uptodate)
>     /* IO error handling */
>
>   But what you say sounds like a reasonable thing from a logical
> perspective.

For reads, that's obviously a common pattern, although even that's
broken in some cases where it is used. But definitely uptodate should
not be set on a read error (although does it need to be explicitly
cleared? I would hope we don't submit a read anyway if the page/buffer
is already uptodate).

But you're right, even changing this for writes would not be a trivial
effort.
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