Re: [Lsf-pc] [LSF/MM/BPF TOPIC] File system checksum offload

Christoph Hellwig
2025-01-31T07:07:49Z

On Thu, Jan 30, 2025 at 08:40:15PM -0800, Theodore Ts'o wrote:
> On Thu, Jan 30, 2025 at 03:39:20PM -0500, Martin K. Petersen wrote:
> > It already works that way. If a device advertises being
> > integrity-capable, the block layer will automatically generate
> > protection information on write and verify received protection
> > information on read. Leveraging hardware-accelerated CRC calculation if
> > the CPU is capable (PCLMULQDQ, etc.).
>
> So I'm confused. If that's the case, why do we need Kanchan Joshi's
> patch to set some magic bio flag and adding a mount option to btrfs?

Well, as stated in reply to the series there really isn't. The
case with a buffer duplicates the existing auto-PI in the block layer,
and the no-buffer cases reduces the protection envelope compared to
using the auto PI.