On 2/22/22 04:59, Gabriel Krisman Bertazi wrote: > I'd like to discuss an interface to implement user space block devices, > while avoiding local network NBD solutions. There has been reiterated > interest in the topic, both from researchers [1] and from the community, > including a proposed session in LSFMM2018 [2] (though I don't think it > happened). > > I've been working on top of the Google iblock implementation to find > something upstreamable and would like to present my design and gather > feedback on some points, in particular zero-copy and overall user space > interface. > > The design I'm pending towards uses special fds opened by the driver to > transfer data to/from the block driver, preferably through direct > splicing as much as possible, to keep data only in kernel space. This > is because, in my use case, the driver usually only manipulates > metadata, while data is forwarded directly through the network, or > similar. It would be neat if we can leverage the existing > splice/copy_file_range syscalls such that we don't ever need to bring > disk data to user space, if we can avoid it. I've also experimented > with regular pipes, But I found no way around keeping a lot of pipes > opened, one for each possible command 'slot'. > > [1] https://dl.acm.org/doi/10.1145/3456727.3463768 This is $15 for non ACM members... Any public download available ? > [2] https://www.spinics.net/lists/linux-fsdevel/msg120674.html > -- Damien Le Moal Western Digital Research
