About 'nvme-pci: fix DMA direction of unmapping integrity data'

[Ming Lei]

On Wed, Nov 29, 2023 at 11:56:50AM -0300, Raphael S. Carvalho wrote:
> I am observing a problem where disk writes are apparently being
> misdirected. File system metadata ends up in file data range for
> example.

Please raise one report in linux-block or linux-nvme if you are asking
for help, and include the following info:

1) kernel release version

2) related drivers or device, nvme or scsi, or dm/md, and how to setup
the device

3) filesystem

4) exact reproduction steps

5) expected result

6) actual result, such as how you conclude that WRITE is misdirected

BTW, is it similar with the following one?

https://bugzilla.kernel.org/show_bug.cgi?id=218158

> 
> I am not completely certain about the problem "nvme-pci: fix DMA
> direction of unmapping integrity data" is trying to fix, could you
> please describe a bit more what the problem is?

dma_unmap_page() should use DMA_TO_DEVICE or DMA_FROM_DEVICE, instead
of block request dir(READ or WRITE), and the issue is actually one
dma-debug warning.

And block request buffer or IO direction isn't supposed to change in its
lifetime, and dma-debug code check if page map & unmap direction is same.

> 
> Can it cause silent data corruption?

No.

Thanks,
Ming