Add API of io_uring_cmd_lease_kbuf() for driver to lease its kernel
buffer to io_uring.
The leased buffer can only be consumed by io_uring OPs in group wide,
and the uring_cmd has to be one group leader.
This way can support generic device zero copy over device buffer in
userspace:
- create one sqe group
- lease one device buffer to io_uring by the group leader of uring_cmd
- io_uring member OPs consume this kernel buffer by passing IOSQE_IO_DRAIN
which isn't used for group member, and mapped to GROUP_KBUF.
- the kernel buffer is returned back after all member OPs are completed
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
include/linux/io_uring/cmd.h | 7 +++++++
io_uring/uring_cmd.c | 13 +++++++++++++
2 files changed, 20 insertions(+)
diff --git a/include/linux/io_uring/cmd.h b/include/linux/io_uring/cmd.h
index c189d36ad55e..bdf7abfa0d8a 100644
--- a/include/linux/io_uring/cmd.h
+++ b/include/linux/io_uring/cmd.h
@@ -60,6 +60,8 @@ void io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd,
/* Execute the request from a blocking context */
void io_uring_cmd_issue_blocking(struct io_uring_cmd *ioucmd);
+int io_uring_cmd_lease_kbuf(struct io_uring_cmd *ioucmd,
+ const struct io_uring_kernel_buf *grp_kbuf);
#else
static inline int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
struct iov_iter *iter, void *ioucmd)
@@ -82,6 +84,11 @@ static inline void io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd,
static inline void io_uring_cmd_issue_blocking(struct io_uring_cmd *ioucmd)
{
}
+static inline int io_uring_cmd_lease_kbuf(struct io_uring_cmd *ioucmd,
+ const struct io_uring_kernel_buf *grp_kbuf)
+{
+ return -EOPNOTSUPP;
+}
#endif
/*
diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index 39c3c816ec78..cf9ab37cf8cc 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -15,6 +15,7 @@
#include "alloc_cache.h"
#include "rsrc.h"
#include "uring_cmd.h"
+#include "kbuf.h"
static struct uring_cache *io_uring_async_get(struct io_kiocb *req)
{
@@ -175,6 +176,18 @@ void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, ssize_t res2,
}
EXPORT_SYMBOL_GPL(io_uring_cmd_done);
+int io_uring_cmd_lease_kbuf(struct io_uring_cmd *ioucmd,
+ const struct io_uring_kernel_buf *grp_kbuf)
+{
+ struct io_kiocb *req = cmd_to_io_kiocb(ioucmd);
+
+ if (unlikely(ioucmd->flags & IORING_URING_CMD_FIXED))
+ return -EINVAL;
+
+ return io_lease_group_kbuf(req, grp_kbuf);
+}
+EXPORT_SYMBOL_GPL(io_uring_cmd_lease_kbuf);
+
static int io_uring_cmd_prep_setup(struct io_kiocb *req,
const struct io_uring_sqe *sqe)
{
--
2.46.0
