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SubjectRe: page_mkwrite caller is racy?
On Mon, 29 Jan 2007, Mark Fasheh wrote:
> On Tue, Jan 30, 2007 at 12:14:24PM +1100, Nick Piggin wrote:
> > This is another discussion, but do we want the page locked here? Or
> > are the filesystems happy to exclude truncate themselves?
>
> No page lock please. Generally, Ocfs2 wants to order cluster locks outside
> of page locks. Also, the sparse b-tree support I'm working on right now will
> need to be able to allocate in ->page_mkwrite() which would become very
> nasty if we came in with the page lock - aside from the additional cluster
> locks taken, ocfs2 will want to zero some adjacent pages (because we support
> atomic allocation up to 1 meg).

Ditto for NTFS. I will need to lock pages on both sides of the page for
large volume cluster sizes thus I will have to drop the page lock if it is
already taken so it might as well not be... Although I do not feel
strongly about it. If the page is locked I will just drop the lock and
then take it again. If possible to not have the page locked that would
make my code a little easier/more efficient I expect...

Best regards,

Anton
--
Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)
Unix Support, Computing Service, University of Cambridge, CB2 3QH, UK
Linux NTFS maintainer, http://www.linux-ntfs.org/
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