On Thursday, 9 November 2006 00:32, Luca Tettamanti wrote:
> On 11/8/06, Rafael J. Wysocki <[EMAIL PROTECTED]> wrote:
> > Hi,
> >
> > On Wednesday, 8 November 2006 18:58, Luca wrote:
> > > I've been working on a small program to find the first valid block of a
> > > swapfile. If I understand it correctly we need the first contiguos cluster
> > > of blocks (not counting the header) which is at least PAGE_SIZE big and
> > > the starting block must be page aligned.
> > > The block number must then be converted in an offset from the start of
> > > the device and the number must be expressed in multiple of PAGE_SIZE.
> > >
> > > This is what I've come up with ;)
> >
> > It doesn't look bad, but you shouldn't skip the header, actually. The
> > header
> > is what we need. ;-)
>
> Oh, right.. you print the offset of page_no == 0. Hum, I think I don't
> understand the layout of a swapfile then; reading swapfile.c I see
> that even the header should be a PAGE_SIZE continuous block, but I
> have test cases where the header is not contiguous on disk (ext2,
> 1024b per block, with artificial fragmentation) - which is why I
> thought that first-page-after-header was needed.
Ouch, that's bad. The swsusp (and ours) swap-writing code will corrupt
the filesystem in such a case, because it assumes the header to be
continuous.
I think we have to understand your test cases at this point. Can you please
post some numbers?
Rafael
--
You never change things by fighting the existing reality.
R. Buckminster Fuller
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