[PATCH V4 04/17] io_uring: support OP_READ/OP_WRITE for fused slave request

Ming Lei
2023-03-24T14:00:03Z

Start to allow fused slave request to support OP_READ/OP_WRITE, and
the buffer can be retrieved from master request.

Once the slave request is completed, the master buffer will be returned
back.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
io_uring/opdef.c | 4 ++++
io_uring/rw.c | 20 ++++++++++++++++++++
2 files changed, 24 insertions(+)

diff --git a/io_uring/opdef.c b/io_uring/opdef.c
index 63b90e8e65f8..9b376df91abd 100644
--- a/io_uring/opdef.c
+++ b/io_uring/opdef.c
@@ -235,6 +235,8 @@ const struct io_issue_def io_issue_defs[] = {
.ioprio = 1,
.iopoll = 1,
.iopoll_queue = 1,
+ .fused_slave = 1,
+ .buf_dir = WRITE,
.prep = io_prep_rw,
.issue = io_read,
},
@@ -248,6 +250,8 @@ const struct io_issue_def io_issue_defs[] = {
.ioprio = 1,
.iopoll = 1,
.iopoll_queue = 1,
+ .fused_slave = 1,
+ .buf_dir = READ,
.prep = io_prep_rw,
.issue = io_write,
},
diff --git a/io_uring/rw.c b/io_uring/rw.c
index 4c233910e200..0c292ef9a40f 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -19,6 +19,7 @@
#include "kbuf.h"
#include "rsrc.h"
#include "rw.h"
+#include "fused_cmd.h"

struct io_rw {
/* NOTE: kiocb has the file as the first member, so don't do it here */
@@ -371,6 +372,17 @@ static struct iovec *__io_import_iovec(int ddir, struct io_kiocb *req,
size_t sqe_len;
ssize_t ret;

+ /*
+ * SLAVE OP passes buffer offset from sqe->addr actually, since
+ * the fused cmd kbuf's mapped start address is zero.
+ */
+ if (req->flags & REQ_F_FUSED_SLAVE) {
+ ret = io_import_buf_for_slave(rw->addr, rw->len, ddir, iter, req);
+ if (ret)
+ return ERR_PTR(ret);
+ return NULL;
+ }
+
if (opcode == IORING_OP_READ_FIXED || opcode == IORING_OP_WRITE_FIXED) {
ret = io_import_fixed(ddir, iter, req->imu, rw->addr, rw->len);
if (ret)
@@ -428,11 +440,19 @@ static inline loff_t *io_kiocb_ppos(struct kiocb *kiocb)
*/
static ssize_t loop_rw_iter(int ddir, struct io_rw *rw, struct iov_iter *iter)
{
+ struct io_kiocb *req = cmd_to_io_kiocb(rw);
struct kiocb *kiocb = &rw->kiocb;
struct file *file = kiocb->ki_filp;
ssize_t ret = 0;
loff_t *ppos;

+ /*
+ * Fused slave req hasn't user buffer, so ->read/->write can't
+ * be supported
+ */
+ if (req->flags & REQ_F_FUSED_SLAVE)
+ return -EOPNOTSUPP;
+
/*
* Don't support polled IO through this interface, and we can't
* support non-blocking either. For the latter, this just causes
--
2.39.2