On 4/2/2024 4:15 PM, Dongyang Li wrote: > Martin, Kanchan, >> >> Kanchan, >> >>> - Generic user interface that user-space can use to exchange meta. >>> A >>> new io_uring opcode IORING_OP_READ/WRITE_META - seems feasible for >>> direct IO. >> >> Yep. I'm interested in this too. Reviving this effort is near the top >> of >> my todo list so I'm happy to collaborate. > If we are going to have a interface to exchange meta/integrity to user- > space, we could also have a interface in kernel to do the same? Not sure if I follow. Currently when blk-integrity allocates/attaches the meta buffer, it decides what to put in it and how to go about integrity generation/verification. When user-space is sending the meta buffer, it will decide what to put/verify. Passed meta buffer will be used directly, and blk-integrity will only facilitate that without doing any in-kernel generation/verification. > It would be useful for some network filesystem/block device drivers > like nbd/drbd/NVMe-oF to use blk-integrity as network checksum, and the > same checksum covers the I/O on the server as well. > > The integrity can be generated on the client and send over network, > on server blk-integrity can just offload to storage. > Verify follows the same principle: on server blk-integrity gets > the PI from storage using the interface, and send over network, > on client we can do the usual verify. > > In the past we tried to achieve this, there's patch to add optional > generate/verify functions and they take priority over the ones from the > integrity profile, and the optional generate/verify functions does the > meta/PI exchange, but that didn't get traction. It would be much better > if we can have an bio interface for this. Any link to the patches? I am not sure what this bio interface is for. Does this mean verify/generate functions to be specified for each bio? Now also in-kernel users can add the meta buffer to the bio. It is up to the bio owner to implement any custom processing on this meta buffer.
