linux-kernel - Re: [RFC PATCH 0/3] Stop clearing uptodate flag on write IO error

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Message-ID: <CA+55aFyUiLq7UZeQD=-MU5ppvEDULiBP8xV0mJqVLL6nFAi7VA@mail.gmail.com>
Date:	Mon, 16 Jan 2012 10:55:55 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Jan Kara <jack@...e.cz>
Cc:	linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Hellwig <hch@...radead.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	LKML <linux-kernel@...r.kernel.org>,
	Edward Shishkin <edward@...hat.com>
Subject: Re: [RFC PATCH 0/3] Stop clearing uptodate flag on write IO error

On Mon, Jan 16, 2012 at 8:01 AM, Jan Kara <jack@...e.cz> wrote:
>
>  Hum, let me understand this. I understand the meaning of buffer_uptodate
> bit as "the buffer has at least as new content as what is on disk". Now
> when storage cannot write the block under the buffer, the contents of the
> buffer is still "at least as new as what is (was) on disk".

No.

Stop making crap up.

If the write fails, the buffer contents have *nothing* to do with what
is on disk.

You don't know what the disk contents are.

So clearly the buffer cannot be up-to-date.

Now, feel free to use *other* arguments for why we shouldn't clear the
up-to-date bit, but using the disk contents as one is pure and utter
garbage. And it is *obviously* pure and utter garbage.

                   Linus
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