From: Keith Busch <kbusch@xxxxxxxxxx> Changes since v2: Fixed incorrect io_uring io_fixed_file index validit checksy: this should have been validating the file_ptr (Ammar) Various micro-optimizations: move up dma in iov type checks, skip iov_iter_advance on async IO (Jens). NVMe driver cleanups splitting the fast and slow paths. NVMe driver prp list setup fixes when using the slow path. Summary: A user address undergoes various represenations for a typical read or write command. Each consumes memory and CPU cycles. When the backing storage is NVMe, the sequence looks something like the following: __user void * struct iov_iter struct pages[] struct bio_vec[] struct scatterlist[] __le64[] Applications will often use the same buffer for many IO, so these potentially costly per-IO transformations to reach the exact same hardware descriptor can be skipped. The io_uring interface already provides a way for users to register buffers to get to 'struct bio_vec[]'. That still leaves the scatterlist needed for the repeated dma_map_sg(), then transform to nvme's PRP list format. This series takes the registered buffers a step further. A block driver can implement a new .dma_map() callback to reach the hardware's DMA mapped address format, and return a cookie so a user can reference it later for any given IO. When used, the block stack can skip significant amounts of code, improving CPU utilization and IOPs. The implementation is currently limited to mapping a registered buffer to a single io_uring fixed file. Keith Busch (7): blk-mq: add ops to dma map bvec file: add ops to dma map bvec iov_iter: introduce type for preregistered dma tags block: add dma tag bio type io_uring: introduce file slot release helper io_uring: add support for dma pre-mapping nvme-pci: implement dma_map support block/bdev.c | 20 +++ block/bio.c | 24 ++- block/blk-merge.c | 19 ++ block/fops.c | 24 ++- drivers/nvme/host/pci.c | 314 +++++++++++++++++++++++++++++++-- fs/file.c | 15 ++ include/linux/bio.h | 22 ++- include/linux/blk-mq.h | 24 +++ include/linux/blk_types.h | 6 +- include/linux/blkdev.h | 16 ++ include/linux/fs.h | 20 +++ include/linux/io_uring_types.h | 2 + include/linux/uio.h | 9 + include/uapi/linux/io_uring.h | 12 ++ io_uring/filetable.c | 34 ++-- io_uring/filetable.h | 10 +- io_uring/io_uring.c | 139 +++++++++++++++ io_uring/net.c | 2 +- io_uring/rsrc.c | 27 +-- io_uring/rsrc.h | 10 +- io_uring/rw.c | 2 +- lib/iov_iter.c | 27 ++- 22 files changed, 724 insertions(+), 54 deletions(-) -- 2.30.2
