Re: [RFC] block layer support for DMA IOMMU bypass mode II

[Jeff Garzik]

On Tue, Jul 08, 2003 at 09:34:27PM +0200, Andi Kleen wrote:
> Overflow is typically deadly because the API does not allow proper
> error handling and most drivers don't check for it. That's especially
> risky for block devices: while pci_map_sg can at least return an error
> not everybody checks for it and when you get an overflow the next
> super block write with such an unchecked error will destroy the file 
> system.

Personally, I've always thought we were kidding ourselves by not doing
the error checking you describe.  From my somewhat-narrow perspective of
network drivers and the libata storage driver, you have to deal with
atomic allocations _anyway_ ...  so why not make sure IOMMU overflow
properly fails at the pci_map_foo level?

	Jeff