[PATCH 00/10] Read/Write with meta/integrity

[Kanchan Joshi <joshi.k@samsung.com>]

This adds a new io_uring interface to specify meta along with
read/write. Beyond reading/writing meta, the interface also enables
(a) flags to control data-integrity checks, (b) application tag.

Block path (direct IO) and NVMe driver are modified to support
this.

First 5 patches are enhancements/fixes in the block/nvme so that user meta buffer
(mostly when it gets split) is handled correctly.
Patch 8 adds the io_uring support.
Patch 9 adds the support for block direct IO, and patch 10 for NVMe.

Interface:
Two new opcodes in io_uring: IORING_OP_READ/WRITE_META.
The leftover space in SQE is used to send meta buffer, its length,
apptag, and meta flags (guard/reftag/apptag check for now). Example
program on how to use the interface is appended below [1]

Another design choice will be not to introduce the new opcodes, and add
new RWF_META flag instead. Open to that in next version.
As for new meta flags, RWF_* seemed a bit precious to use. Hence took the route
to carve those within the SQE itself.

Performance:
of non-meta io is not affected due to these patches.

Testing:
has been done by modifying fio to use this interface.
https://github.com/SamsungDS/fio/commits/feat/test-meta-v2

Changes since RFC:
- modify io_uring plumbing based on recent async handling state changes
- fixes/enhancements to correctly handle the split for meta buffer
- add flags to specify guard/reftag/apptag checks
- add support to send apptag

[1]
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <linux/io_uring.h>
#include <linux/types.h>
#include "liburing.h"

/* write data/meta. read both. compare. send apptag too.
* prerequisite:
* unprotected xfer: format namespace with 4KB + 8b, pi_type = 0
* protected xfer: format namespace with 4KB + 8b, pi_type = 1
*/

#define DATA_LEN 4096
#define META_LEN 8

struct t10_pi_tuple {
        __be16  guard;
        __be16  apptag;
        __be32  reftag;
};

int main(int argc, char *argv[])
{
         struct io_uring ring;
         struct io_uring_sqe *sqe = NULL;
         struct io_uring_cqe *cqe = NULL;
         void *wdb,*rdb;
         char wmb[META_LEN], rmb[META_LEN];
         char *data_str = "data buffer";
         char *meta_str = "meta";
         int fd, ret, blksize;
         struct stat fstat;
         unsigned long long offset = DATA_LEN;
         struct t10_pi_tuple *pi;

         if (argc != 2) {
                 fprintf(stderr, "Usage: %s <block-device>", argv[0]);
                 return 1;
         };

         if (stat(argv[1], &fstat) == 0) {
                 blksize = (int)fstat.st_blksize;
         } else {
                 perror("stat");
                 return 1;
         }

         if (posix_memalign(&wdb, blksize, DATA_LEN)) {
                 perror("posix_memalign failed");
                 return 1;
         }
         if (posix_memalign(&rdb, blksize, DATA_LEN)) {
                 perror("posix_memalign failed");
                 return 1;
         }

         strcpy(wdb, data_str);
         strcpy(wmb, meta_str);

         fd = open(argv[1], O_RDWR | O_DIRECT);
         if (fd < 0) {
                 printf("Error in opening device\n");
                 return 0;
         }

         ret = io_uring_queue_init(8, &ring, 0);
         if (ret) {
                 fprintf(stderr, "ring setup failed: %d\n", ret);
                 return 1;
         }

         /* write data + meta-buffer to device */
         sqe = io_uring_get_sqe(&ring);
         if (!sqe) {
                 fprintf(stderr, "get sqe failed\n");
                 return 1;
         }

         io_uring_prep_write(sqe, fd, wdb, DATA_LEN, offset);
         sqe->opcode = IORING_OP_WRITE_META;
         sqe->meta_addr = (__u64)wmb;
         sqe->meta_len = META_LEN;
         /* flags to ask for guard/reftag/apptag*/
         sqe->meta_flags = META_CHK_APPTAG;
         sqe->apptag = 0x1234;

         pi = (struct t10_pi_tuple *)wmb;
         pi->apptag = 0x3412;

         ret = io_uring_submit(&ring);
         if (ret <= 0) {
                 fprintf(stderr, "sqe submit failed: %d\n", ret);
                 return 1;
         }

         ret = io_uring_wait_cqe(&ring, &cqe);
         if (!cqe) {
                 fprintf(stderr, "cqe is NULL :%d\n", ret);
                 return 1;
         }
         if (cqe->res < 0) {
                 fprintf(stderr, "write cqe failure: %d", cqe->res);
                 return 1;
         }

         io_uring_cqe_seen(&ring, cqe);

         /* read data + meta-buffer back from device */
         sqe = io_uring_get_sqe(&ring);
         if (!sqe) {
                 fprintf(stderr, "get sqe failed\n");
                 return 1;
         }

         io_uring_prep_read(sqe, fd, rdb, DATA_LEN, offset);
         sqe->opcode = IORING_OP_READ_META;
         sqe->meta_addr = (__u64)rmb;
         sqe->meta_len = META_LEN;
         sqe->meta_flags = META_CHK_APPTAG;
         sqe->apptag = 0x1234;

         ret = io_uring_submit(&ring);
         if (ret <= 0) {
                 fprintf(stderr, "sqe submit failed: %d\n", ret);
                 return 1;
         }

         ret = io_uring_wait_cqe(&ring, &cqe);
         if (!cqe) {
                 fprintf(stderr, "cqe is NULL :%d\n", ret);
                 return 1;
         }

         if (cqe->res < 0) {
                 fprintf(stderr, "read cqe failure: %d", cqe->res);
                 return 1;
         }
         io_uring_cqe_seen(&ring, cqe);

         if (strncmp(wmb, rmb, META_LEN))
                 printf("Failure: meta mismatch!, wmb=%s, rmb=%s\n", wmb, rmb);

         if (strncmp(wdb, rdb, DATA_LEN))
                 printf("Failure: data mismatch!\n");

         io_uring_queue_exit(&ring);
         free(rdb);
         free(wdb);
         return 0;
}


Anuj Gupta (6):
  block: set bip_vcnt correctly
  block: copy bip_max_vcnt vecs instead of bip_vcnt during clone
  block: copy result back to user meta buffer correctly in case of split
  block: avoid unpinning/freeing the bio_vec incase of cloned bio
  block: modify bio_integrity_map_user argument
  io_uring/rw: add support to send meta along with read/write

Kanchan Joshi (4):
  block, nvme: modify rq_integrity_vec function
  block: define meta io descriptor
  block: add support to send meta buffer
  nvme: add separate handling for user integrity buffer

 block/bio-integrity.c         | 69 +++++++++++++++++++++++--------
 block/fops.c                  |  9 +++++
 block/t10-pi.c                |  6 +++
 drivers/nvme/host/core.c      | 36 ++++++++++++++++-
 drivers/nvme/host/ioctl.c     | 11 ++++-
 drivers/nvme/host/pci.c       |  9 +++--
 include/linux/bio.h           | 23 +++++++++--
 include/linux/blk-integrity.h | 13 +++---
 include/linux/fs.h            |  1 +
 include/uapi/linux/io_uring.h | 15 +++++++
 io_uring/io_uring.c           |  4 ++
 io_uring/opdef.c              | 30 ++++++++++++++
 io_uring/rw.c                 | 76 +++++++++++++++++++++++++++++++++--
 io_uring/rw.h                 | 11 ++++-
 14 files changed, 276 insertions(+), 37 deletions(-)


base-commit: 24c3fc5c75c5b9d471783b4a4958748243828613
-- 
2.25.1