io_uring/net: support bundles for send

If IORING_OP_SEND is used with provided buffers, the caller may also
set IORING_RECVSEND_BUNDLE to turn it into a multi-buffer send. The idea
is that an application can fill outgoing buffers in a provided buffer
group, and then arm a single send that will service them all. Once
there are no more buffers to send, or if the requested length has
been sent, the request posts a single completion for all the buffers.

This only enables it for IORING_OP_SEND, IORING_OP_SENDMSG is coming
in a separate patch. However, this patch does do a lot of the prep
work that makes wiring up the sendmsg variant pretty trivial. They
share the prep side.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index a7f847543a7f19ad83a18640d2eae5fa408f43f5..7f583927c908d364d2f7423b433a7fe693d8b704 100644 (file)
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -351,11 +351,20 @@ enum io_uring_op {
  *                             0 is reported if zerocopy was actually possible.
  *                             IORING_NOTIF_USAGE_ZC_COPIED if data was copied
  *                             (at least partially).
+ *
+ * IORING_RECVSEND_BUNDLE      Used with IOSQE_BUFFER_SELECT. If set, send will
+ *                             grab as many buffers from the buffer group ID
+ *                             given and send them all. The completion result
+ *                             will be the number of buffers send, with the
+ *                             starting buffer ID in cqe->flags as per usual
+ *                             for provided buffer usage. The buffers will be
+ *                             contigious from the starting buffer ID.
  */
 #define IORING_RECVSEND_POLL_FIRST     (1U << 0)
 #define IORING_RECV_MULTISHOT          (1U << 1)
 #define IORING_RECVSEND_FIXED_BUF      (1U << 2)
 #define IORING_SEND_ZC_REPORT_USAGE    (1U << 3)
+#define IORING_RECVSEND_BUNDLE         (1U << 4)
 
 /*
  * cqe.res for IORING_CQE_F_NOTIF if

diff --git a/io_uring/net.c b/io_uring/net.c
index 13685d13358225a446e4f846df982bfe56d14348..3e326576254be710f753767fbf320d5e8ad86399 100644 (file)
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -57,7 +57,7 @@ struct io_sr_msg {
                struct user_msghdr __user       *umsg;
                void __user                     *buf;
        };
-       unsigned                        len;
+       int                             len;
        unsigned                        done_io;
        unsigned                        msg_flags;
        unsigned                        nr_multishot_loops;
@@ -389,6 +389,8 @@ static int io_sendmsg_prep_setup(struct io_kiocb *req, int is_msg)
        return ret;
 }
 
+#define SENDMSG_FLAGS (IORING_RECVSEND_POLL_FIRST | IORING_RECVSEND_BUNDLE)
+
 int io_sendmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
@@ -407,11 +409,20 @@ int io_sendmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
        sr->umsg = u64_to_user_ptr(READ_ONCE(sqe->addr));
        sr->len = READ_ONCE(sqe->len);
        sr->flags = READ_ONCE(sqe->ioprio);
-       if (sr->flags & ~IORING_RECVSEND_POLL_FIRST)
+       if (sr->flags & ~SENDMSG_FLAGS)
                return -EINVAL;
        sr->msg_flags = READ_ONCE(sqe->msg_flags) | MSG_NOSIGNAL;
        if (sr->msg_flags & MSG_DONTWAIT)
                req->flags |= REQ_F_NOWAIT;
+       if (sr->flags & IORING_RECVSEND_BUNDLE) {
+               if (req->opcode == IORING_OP_SENDMSG)
+                       return -EINVAL;
+               if (!(req->flags & REQ_F_BUFFER_SELECT))
+                       return -EINVAL;
+               sr->msg_flags |= MSG_WAITALL;
+               sr->buf_group = req->buf_index;
+               req->buf_list = NULL;
+       }
 
 #ifdef CONFIG_COMPAT
        if (req->ctx->compat)
@@ -427,6 +438,79 @@ static void io_req_msg_cleanup(struct io_kiocb *req,
        io_netmsg_recycle(req, issue_flags);
 }
 
+/*
+ * For bundle completions, we need to figure out how many segments we consumed.
+ * A bundle could be using a single ITER_UBUF if that's all we mapped, or it
+ * could be using an ITER_IOVEC. If the latter, then if we consumed all of
+ * the segments, then it's a trivial questiont o answer. If we have residual
+ * data in the iter, then loop the segments to figure out how much we
+ * transferred.
+ */
+static int io_bundle_nbufs(struct io_async_msghdr *kmsg, int ret)
+{
+       struct iovec *iov;
+       int nbufs;
+
+       /* no data is always zero segments, and a ubuf is always 1 segment */
+       if (ret <= 0)
+               return 0;
+       if (iter_is_ubuf(&kmsg->msg.msg_iter))
+               return 1;
+
+       iov = kmsg->free_iov;
+       if (!iov)
+               iov = &kmsg->fast_iov;
+
+       /* if all data was transferred, it's basic pointer math */
+       if (!iov_iter_count(&kmsg->msg.msg_iter))
+               return iter_iov(&kmsg->msg.msg_iter) - iov;
+
+       /* short transfer, count segments */
+       nbufs = 0;
+       do {
+               int this_len = min_t(int, iov[nbufs].iov_len, ret);
+
+               nbufs++;
+               ret -= this_len;
+       } while (ret);
+
+       return nbufs;
+}
+
+static inline bool io_send_finish(struct io_kiocb *req, int *ret,
+                                 struct io_async_msghdr *kmsg,
+                                 unsigned issue_flags)
+{
+       struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
+       bool bundle_finished = *ret <= 0;
+       unsigned int cflags;
+
+       if (!(sr->flags & IORING_RECVSEND_BUNDLE)) {
+               cflags = io_put_kbuf(req, issue_flags);
+               goto finish;
+       }
+
+       cflags = io_put_kbufs(req, io_bundle_nbufs(kmsg, *ret), issue_flags);
+
+       if (bundle_finished || req->flags & REQ_F_BL_EMPTY)
+               goto finish;
+
+       /*
+        * Fill CQE for this receive and see if we should keep trying to
+        * receive from this socket.
+        */
+       if (io_req_post_cqe(req, *ret, cflags | IORING_CQE_F_MORE)) {
+               io_mshot_prep_retry(req, kmsg);
+               return false;
+       }
+
+       /* Otherwise stop bundle and use the current result. */
+finish:
+       io_req_set_res(req, *ret, cflags);
+       *ret = IOU_OK;
+       return true;
+}
+
 int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
 {
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
@@ -482,7 +566,6 @@ int io_send(struct io_kiocb *req, unsigned int issue_flags)
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
        struct io_async_msghdr *kmsg = req->async_data;
        struct socket *sock;
-       unsigned int cflags;
        unsigned flags;
        int min_ret = 0;
        int ret;
@@ -495,21 +578,47 @@ int io_send(struct io_kiocb *req, unsigned int issue_flags)
            (sr->flags & IORING_RECVSEND_POLL_FIRST))
                return -EAGAIN;
 
+       flags = sr->msg_flags;
+       if (issue_flags & IO_URING_F_NONBLOCK)
+               flags |= MSG_DONTWAIT;
+
+retry_bundle:
        if (io_do_buffer_select(req)) {
-               size_t len = sr->len;
-               void __user *buf;
+               struct buf_sel_arg arg = {
+                       .iovs = &kmsg->fast_iov,
+                       .max_len = min_not_zero(sr->len, INT_MAX),
+                       .nr_iovs = 1,
+                       .mode = KBUF_MODE_EXPAND,
+               };
+
+               if (kmsg->free_iov) {
+                       arg.nr_iovs = kmsg->free_iov_nr;
+                       arg.iovs = kmsg->free_iov;
+                       arg.mode |= KBUF_MODE_FREE;
+               }
 
-               buf = io_buffer_select(req, &len, issue_flags);
-               if (unlikely(!buf))
-                       return -ENOBUFS;
-               sr->buf = buf;
-               sr->len = len;
+               if (!(sr->flags & IORING_RECVSEND_BUNDLE))
+                       arg.nr_iovs = 1;
+
+               ret = io_buffers_select(req, &arg, issue_flags);
+               if (unlikely(ret < 0))
+                       return ret;
+
+               sr->len = arg.out_len;
+               iov_iter_init(&kmsg->msg.msg_iter, ITER_SOURCE, arg.iovs, ret,
+                               arg.out_len);
+               if (arg.iovs != &kmsg->fast_iov && arg.iovs != kmsg->free_iov) {
+                       kmsg->free_iov_nr = ret;
+                       kmsg->free_iov = arg.iovs;
+               }
        }
 
-       flags = sr->msg_flags;
-       if (issue_flags & IO_URING_F_NONBLOCK)
-               flags |= MSG_DONTWAIT;
-       if (flags & MSG_WAITALL)
+       /*
+        * If MSG_WAITALL is set, or this is a bundle send, then we need
+        * the full amount. If just bundle is set, if we do a short send
+        * then we complete the bundle sequence rather than continue on.
+        */
+       if (flags & MSG_WAITALL || sr->flags & IORING_RECVSEND_BUNDLE)
                min_ret = iov_iter_count(&kmsg->msg.msg_iter);
 
        flags &= ~MSG_INTERNAL_SENDMSG_FLAGS;
@@ -534,10 +643,12 @@ int io_send(struct io_kiocb *req, unsigned int issue_flags)
                ret += sr->done_io;
        else if (sr->done_io)
                ret = sr->done_io;
+
+       if (!io_send_finish(req, &ret, kmsg, issue_flags))
+               goto retry_bundle;
+
        io_req_msg_cleanup(req, issue_flags);
-       cflags = io_put_kbuf(req, issue_flags);
-       io_req_set_res(req, ret, cflags);
-       return IOU_OK;
+       return ret;
 }
 
 static int io_recvmsg_mshot_prep(struct io_kiocb *req,