io_uring: optimise io_init_req() flags setting

Invalid req->flags are tolerated by free/put well, avoid this dancing
needlessly presetting it to zero, and then not even resetting but
modifying it, i.e. "|=".

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 776531f..2e8cb73 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6806,14 +6806,15 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
 {
        struct io_submit_state *state;
        unsigned int sqe_flags;
-       int id, ret;
+       int id, ret = 0;
 
        req->opcode = READ_ONCE(sqe->opcode);
+       /* same numerical values with corresponding REQ_F_*, safe to copy */
+       req->flags = sqe_flags = READ_ONCE(sqe->flags);
        req->user_data = READ_ONCE(sqe->user_data);
        req->async_data = NULL;
        req->file = NULL;
        req->ctx = ctx;
-       req->flags = 0;
        req->link = NULL;
        req->fixed_rsrc_refs = NULL;
        /* one is dropped after submission, the other at completion */
@@ -6821,17 +6822,16 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
        req->task = current;
        req->result = 0;
 
+       /* enforce forwards compatibility on users */
+       if (unlikely(sqe_flags & ~SQE_VALID_FLAGS))
+               return -EINVAL;
+
        if (unlikely(req->opcode >= IORING_OP_LAST))
                return -EINVAL;
 
        if (unlikely(io_sq_thread_acquire_mm_files(ctx, req)))
                return -EFAULT;
 
-       sqe_flags = READ_ONCE(sqe->flags);
-       /* enforce forwards compatibility on users */
-       if (unlikely(sqe_flags & ~SQE_VALID_FLAGS))
-               return -EINVAL;
-
        if (unlikely(!io_check_restriction(ctx, req, sqe_flags)))
                return -EACCES;
 
@@ -6854,8 +6854,6 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
                req->work.flags |= IO_WQ_WORK_CREDS;
        }
 
-       /* same numerical values with corresponding REQ_F_*, safe to copy */
-       req->flags |= sqe_flags;
        state = &ctx->submit_state;
 
        /*
@@ -6868,7 +6866,6 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
                state->plug_started = true;
        }
 
-       ret = 0;
        if (io_op_defs[req->opcode].needs_file) {
                bool fixed = req->flags & REQ_F_FIXED_FILE;