> On May 19, 2021, at 7:13 AM, Pavel Begunkov <asml.silence@xxxxxxxxx> wrote:
>
> Add a BPF_FUNC_iouring_queue_sqe BPF function as a demonstration of
> submmiting a new request by a BPF request.
>
> Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
> ---
> fs/io_uring.c | 51 ++++++++++++++++++++++++++++++++++++----
> include/uapi/linux/bpf.h | 1 +
> 2 files changed, 48 insertions(+), 4 deletions(-)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 20fddc5945f2..aae786291c57 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -882,6 +882,7 @@ struct io_defer_entry {
> };
>
> struct io_bpf_ctx {
> + struct io_ring_ctx *ctx;
> };
>
> struct io_op_def {
> @@ -6681,7 +6682,8 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
> ret = -EBADF;
> }
>
> - state->ios_left--;
> + if (state->ios_left > 1)
> + state->ios_left--;
> return ret;
> }
>
> @@ -10345,10 +10347,50 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
> return ret;
> }
>
> +BPF_CALL_3(io_bpf_queue_sqe, struct io_bpf_ctx *, bpf_ctx,
> + const struct io_uring_sqe *, sqe,
> + u32, sqe_len)
> +{
> + struct io_ring_ctx *ctx = bpf_ctx->ctx;
> + struct io_kiocb *req;
> +
> + if (sqe_len != sizeof(struct io_uring_sqe))
> + return -EINVAL;
> +
> + req = io_alloc_req(ctx);
> + if (unlikely(!req))
> + return -ENOMEM;
> + if (!percpu_ref_tryget_many(&ctx->refs, 1)) {
> + kmem_cache_free(req_cachep, req);
> + return -EAGAIN;
> + }
> + percpu_counter_add(¤t->io_uring->inflight, 1);
> + refcount_add(1, ¤t->usage);
> +
> + /* returns number of submitted SQEs or an error */
> + return !io_submit_sqe(ctx, req, sqe);
> +}
> +
> +const struct bpf_func_proto io_bpf_queue_sqe_proto = {
> + .func = io_bpf_queue_sqe,
> + .gpl_only = false,
> + .ret_type = RET_INTEGER,
> + .arg1_type = ARG_PTR_TO_CTX,
> + .arg2_type = ARG_PTR_TO_MEM,
> + .arg3_type = ARG_CONST_SIZE,
> +};
> +
> static const struct bpf_func_proto *
> io_bpf_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> {
> - return bpf_base_func_proto(func_id);
> + switch (func_id) {
> + case BPF_FUNC_copy_from_user:
> + return prog->aux->sleepable ? &bpf_copy_from_user_proto : NULL;
> + case BPF_FUNC_iouring_queue_sqe:
> + return prog->aux->sleepable ? &io_bpf_queue_sqe_proto : NULL;
> + default:
> + return bpf_base_func_proto(func_id);
> + }
> }
>
> static bool io_bpf_is_valid_access(int off, int size,
> @@ -10379,9 +10421,10 @@ static void io_bpf_run(struct io_kiocb *req, unsigned int issue_flags)
> atomic_read(&req->task->io_uring->in_idle)))
> goto done;
>
> - memset(&bpf_ctx, 0, sizeof(bpf_ctx));
> + bpf_ctx.ctx = ctx;
> prog = req->bpf.prog;
>
> + io_submit_state_start(&ctx->submit_state, 1);
> if (prog->aux->sleepable) {
> rcu_read_lock();
> bpf_prog_run_pin_on_cpu(req->bpf.prog, &bpf_ctx);
> @@ -10389,7 +10432,7 @@ static void io_bpf_run(struct io_kiocb *req, unsigned int issue_flags)
> } else {
> bpf_prog_run_pin_on_cpu(req->bpf.prog, &bpf_ctx);
> }
> -
> + io_submit_state_end(&ctx->submit_state, ctx);
> ret = 0;
> done:
> __io_req_complete(req, issue_flags, ret, 0);
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index de544f0fbeef..cc268f749a7d 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -4082,6 +4082,7 @@ union bpf_attr {
> FN(ima_inode_hash), \
> FN(sock_from_file), \
> FN(check_mtu), \
> + FN(iouring_queue_sqe), \
We need to describe this function in the comment above, just like 20/23 does.
> /* */
>
> /* integer value in 'imm' field of BPF_CALL instruction selects which helper
> --
> 2.31.1
>
