On 2/27/20 12:53 AM, Christoph Hellwig wrote: > On Wed, Feb 26, 2020 at 08:58:46AM -0700, Jens Axboe wrote: >> Yeah, should probably be a RWF_ flag instead, and a 64-bit SQE field >> for the PI data. The 'last iovec is PI' is kind of icky. > > Abusing an iovec (although I though of the first once when looking > into it) looks really horrible, but has two huge advantages: > > - it doesn't require passing another argument all the way down > the I/O stack > - it works with all the vectored interfaces that take a flag > argument, so not just io_uring, but also preadv2/pwritev2 and aio. > And while I don't care too much about the last I think preadv2 > and pwritev2 are valuable to support. > Indeed, actually the 'last iovec is PI' idea was learned from Darrick's original patch which support PI passthrough via aio. https://www.mail-archive.com/linux-scsi@xxxxxxxxxxxxxxx/msg27537.html
