Re: 2.6.19 file content corruption on ext3

From: Linus Torvalds
Date: Thu Dec 28 2006 - 18:55:12 EST




On Thu, 28 Dec 2006, Anton Altaparmakov wrote:
>
> But are chunks 3 and 4 in separate buffer heads? Sorry could not see it
> immediately from the output you showed...

No, this is a 4kB filesystem. A single bh per page.

> It is just that there may be a different cause rather than buffer dirty
> state...

Sure.

> A shot in the dark I know but it could perhaps be that a "COW for
> MAP_PRIVATE" like event happens when the page is dirty already thus the
> second write never actually makes it to the shared page thus it never gets
> written out.

There are no private mappings anywhere, and no forks. Just a single mmap
(well, we unmap and remap in order to force the page cache to be
invalidated properly with the posix_fadvise() thing, but that's literally
the only user).

Linus
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