Re: [PATCH]: ufs: ufs_get_locked_patch race fix
From: Andrew Morton
Date: Tue Aug 01 2006 - 03:38:01 EST
On Tue, 1 Aug 2006 11:30:43 +0400
Evgeniy Dushistov <dushistov@xxxxxxx> wrote:
> On Mon, Jul 31, 2006 at 11:02:51PM -0700, Andrew Morton wrote:
> > On Mon, 31 Jul 2006 16:57:02 +0400
> > Evgeniy Dushistov <dushistov@xxxxxxx> wrote:
> > Looks good to me.
> > Is there any need to be checking ->index? Normally we simply use the
> > sequence:
> > lock_page(page);
> > if (page->mapping == NULL)
> > /* truncate got there first */
> > to handle this case.
> Yes, I made it in analogy with `find_lock_page' and missed fact
> that if we increment usage counter of page, we have no need to check
OK. find_lock_page() has the splice stuff in it.
> Need another patch?
Is OK, I updated it.
I'm not sure that the `goto repeat' is needed if truncate got there first,
really - if truncate took the page down then it's now outside i_size and
shouldn't be coming back.
If the page _can_ come back then this code is all rather problematic.
Because this means that the page can come back (via an extending write())
one nanosecond after ufs_get_locked_page() returns NULL. Won't the callers
of ufs_get_locked_page() get confused by that?
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