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Subject[RFC v2 15/19] io_uring: sendzc with fixed buffers
Date
Allow zerocopy sends to use fixed buffers.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
fs/io_uring.c | 19 +++++++++++++++++--
include/uapi/linux/io_uring.h | 1 +
2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 40a8d7799be3..654023ba0b91 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5048,7 +5048,7 @@ static int io_send(struct io_kiocb *req, unsigned int issue_flags)
return 0;
}

-#define IO_SENDZC_VALID_FLAGS IORING_SENDZC_FLUSH
+#define IO_SENDZC_VALID_FLAGS (IORING_SENDZC_FLUSH | IORING_SENDZC_FIXED_BUF)

static int io_sendzc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
@@ -5078,6 +5078,15 @@ static int io_sendzc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
if (req->msgzc.zc_flags & ~IO_SENDZC_VALID_FLAGS)
return -EINVAL;

+ if (req->msgzc.zc_flags & IORING_SENDZC_FIXED_BUF) {
+ idx = READ_ONCE(sqe->buf_index);
+ if (unlikely(idx >= ctx->nr_user_bufs))
+ return -EFAULT;
+ idx = array_index_nospec(idx, ctx->nr_user_bufs);
+ req->imu = READ_ONCE(ctx->user_bufs[idx]);
+ io_req_set_rsrc_node(req, ctx);
+ }
+
#ifdef CONFIG_COMPAT
if (req->ctx->compat)
sr->msg_flags |= MSG_CMSG_COMPAT;
@@ -5101,7 +5110,13 @@ static int io_sendzc(struct io_kiocb *req, unsigned int issue_flags)
if (unlikely(!sock))
return -ENOTSOCK;

- ret = import_single_range(WRITE, sr->buf, sr->len, &iov, &msg.msg_iter);
+ if (req->msgzc.zc_flags & IORING_SENDZC_FIXED_BUF) {
+ ret = __io_import_fixed(WRITE, &msg.msg_iter, req->imu,
+ (u64)sr->buf, sr->len);
+ } else {
+ ret = import_single_range(WRITE, sr->buf, sr->len, &iov,
+ &msg.msg_iter);
+ }
if (unlikely(ret))
return ret;

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index ac18e8e6f86f..740af1d0409f 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -189,6 +189,7 @@ enum {

enum {
IORING_SENDZC_FLUSH = (1U << 0),
+ IORING_SENDZC_FIXED_BUF = (1U << 1),
};

/*
--
2.34.1
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