Re: The INN/mmap bug

From: Linus Torvalds (torvalds@transmeta.com)
Date: Sun Sep 17 2000 - 22:33:54 EST


On Sun, 17 Sep 2000, Alexander Viro wrote:
>
> Ugh. OK, first of all, patch is _not_ correct. Doesn't zero out the end of
> partial block.
> <note to myself: no patches before the first cup of coffee>

Yeah. See my other mail - I don't think the patch is needed at all,
although I'm convinced that it would actually hide the problem for the
particular case of INN (zeroing out the partial block is not an issue
there, as truncate will have done it - it's really only protection against
badly behaved software and shouldn't matter to any "regular" use).

> We know that ->writepage() is called and we know that data doesn't get
> to the disk. How can it happen? If we can... Oh, fsck. Linus, we could
> very well lose the buffers since the moment when page had been read.
> See what happens? We recreate the buffer ring for the page and it's
> nowhere near "everything uptodate" state.

Yeah. See my suggested fix in the other mail. We just must not read in
buffers for pages that are already up-to-date.

                Linus

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