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

From: J. Bruce Fields
Date: Thu Jun 03 2010 - 12:30:18 EST


On Thu, Jun 03, 2010 at 07:09:52PM +0300, 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.
>
> People that care:
> - Mirror and RAID people that need on disk consistency.
> - Network storage that wants data checksum.

Yes, nfs/rpcsec_gss code is an example of code that tries to sign pages
containing data that could change underneath us. I don't know if we've
seen it in practice.

--b.

> - 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
>
> Boaz
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