Re: [PATCH v3 00/20] Userspace P2PDMA with O_DIRECT NVMe devices

On Wed, Sep 29, 2021 at 03:50:02PM -0600, Logan Gunthorpe wrote:

On 2021-09-28 2:02 p.m., Jason Gunthorpe wrote:

quoted

On Thu, Sep 16, 2021 at 05:40:40PM -0600, Logan Gunthorpe wrote:

quoted

Hi,

This patchset continues my work to add userspace P2PDMA access using
O_DIRECT NVMe devices. My last posting[1] just included the first 13
patches in this series, but the early P2PDMA cleanup and map_sg error
changes from that series have been merged into v5.15-rc1. To address
concerns that that series did not add any new functionality, I've added
back the userspcae functionality from the original RFC[2] (but improved
based on the original feedback).

I really think this is the best series yet, it really looks nice
overall. I know the sg flag was a bit of a debate at the start, but it
serves an undeniable purpose and the resulting standard DMA APIs 'just
working' is really clean.

Actually, so far, nobody has said anything negative about using the SG flag.

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There is more possible here, we could also pass the new GUP flag in the
ib_umem code..

Yes, that would be very useful.

You might actually prefer to do that then the bio changes to get the
infrastructur merged as it seems less "core"

Jason