io_uring: return hint on whether more data is available after receive

For now just use a CQE flag for this, with big CQE support we could
return the actual number of bytes left.

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

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 5a0388b..20c5d29 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5948,6 +5948,7 @@ static int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
        struct io_sr_msg *sr = &req->sr_msg;
        struct socket *sock;
        struct io_buffer *kbuf;
+       unsigned int cflags;
        unsigned flags;
        int ret, min_ret = 0;
        bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
@@ -5981,6 +5982,8 @@ static int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
        if (flags & MSG_WAITALL)
                min_ret = iov_iter_count(&kmsg->msg.msg_iter);
 
+       kmsg->msg.msg_get_inq = 1;
+
        ret = __sys_recvmsg_sock(sock, &kmsg->msg, req->sr_msg.umsg,
                                        kmsg->uaddr, flags);
        if (ret < min_ret) {
@@ -6006,7 +6009,10 @@ static int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
                ret += sr->done_io;
        else if (sr->done_io)
                ret = sr->done_io;
-       __io_req_complete(req, issue_flags, ret, io_put_kbuf(req, issue_flags));
+       cflags = io_put_kbuf(req, issue_flags);
+       if (kmsg->msg.msg_inq)
+               cflags |= IORING_CQE_F_SOCK_NONEMPTY;
+       __io_req_complete(req, issue_flags, ret, cflags);
        return 0;
 }
 
@@ -6018,6 +6024,7 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags)
        void __user *buf = sr->buf;
        struct socket *sock;
        struct iovec iov;
+       unsigned int cflags;
        unsigned flags;
        int ret, min_ret = 0;
        bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
@@ -6038,11 +6045,12 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags)
                goto out_free;
 
        msg.msg_name = NULL;
+       msg.msg_namelen = 0;
        msg.msg_control = NULL;
+       msg.msg_get_inq = 1;
+       msg.msg_flags = 0;
        msg.msg_controllen = 0;
-       msg.msg_namelen = 0;
        msg.msg_iocb = NULL;
-       msg.msg_flags = 0;
 
        flags = req->sr_msg.msg_flags;
        if (force_nonblock)
@@ -6073,7 +6081,10 @@ out_free:
                ret += sr->done_io;
        else if (sr->done_io)
                ret = sr->done_io;
-       __io_req_complete(req, issue_flags, ret, io_put_kbuf(req, issue_flags));
+       cflags = io_put_kbuf(req, issue_flags);
+       if (msg.msg_inq)
+               cflags |= IORING_CQE_F_SOCK_NONEMPTY;
+       __io_req_complete(req, issue_flags, ret, cflags);
        return 0;
 }
 

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 49d1f39..92d1799 100644 (file)
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -220,9 +220,11 @@ struct io_uring_cqe {
  *
  * IORING_CQE_F_BUFFER If set, the upper 16 bits are the buffer ID
  * IORING_CQE_F_MORE   If set, parent SQE will generate more CQE entries
+ * IORING_CQE_F_SOCK_NONEMPTY  If set, more data to read after socket recv
  */
 #define IORING_CQE_F_BUFFER            (1U << 0)
 #define IORING_CQE_F_MORE              (1U << 1)
+#define IORING_CQE_F_SOCK_NONEMPTY     (1U << 2)
 
 enum {
        IORING_CQE_BUFFER_SHIFT         = 16,