Re: [Lsf10-pc] [LFS/VM TOPIC] Stable pages while IO (was Wrong DIF guard tag on ext2 write)

["J. Bruce Fields" <bfields@fieldses.org>]

On Fri, Jun 04, 2010 at 06:23:32PM +0200, Jan Kara wrote:
> On Thu 03-06-10 19:09:52, Boaz Harrosh wrote:
> > [Topic]
> > How to not let pages change while in IO
> > 
> > [Abstract]
> > As seen in a long thread on the fsdvel scsi mailing lists. Lots of
> > people have headaches and sleep less nights because individual pages
> > can change while in IO and/or DMA. Though each one as slightly different
> > needs, the mechanics look to be the same.
>   Hmm, I don't think it's really about "how to not let pages change" - that
> is doable by using wait_on_page_writeback() in ->page_mkwrite and
> ->write_begin.

Will the same work for the NFS server checksumming page data in read
replies?

--b.

> I think the discussion is more about whether we should do it
> or whether we should rechecksum and resubmit IO in case of checksum failure
> as Nick proposed...
> 
> 								Honza
> > People that care:
> > - Mirror and RAID people that need on disk consistency.
> > - Network storage that wants data checksum.
> > - DIF/DIX people
> > - ...
> > 
> > I for one know nothing of the subject but am a RAID person and would
> > like a solution that does not force me to copy the complete data load.
> > 
> > Please lets get all the VM VFS and drivers people in one room and see
> > if we can have a Linux solution to this problem
> -- 
> Jan Kara <jack@suse.cz>
> SUSE Labs, CR
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