io_uring: get rid of delayed mm check

Fail fast if can't grab mm, so past that requests always have an mm
when required. This allows us to remove req->user altogether.

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 77f22c3..1859e86 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -553,7 +553,6 @@ struct io_kiocb {
         * llist_node is only used for poll deferred completions
         */
        struct llist_node               llist_node;
-       bool                            has_user;
        bool                            in_async;
        bool                            needs_fixed_file;
        u8                              opcode;
@@ -2056,9 +2055,6 @@ static ssize_t io_import_iovec(int rw, struct io_kiocb *req,
                return iorw->size;
        }
 
-       if (!req->has_user)
-               return -EFAULT;
-
 #ifdef CONFIG_COMPAT
        if (req->ctx->compat)
                return compat_import_iovec(rw, buf, sqe_len, UIO_FASTIOV,
@@ -4446,7 +4442,6 @@ static void io_wq_submit_work(struct io_wq_work **workptr)
        }
 
        if (!ret) {
-               req->has_user = (work->flags & IO_WQ_WORK_HAS_MM) != 0;
                req->in_async = true;
                do {
                        ret = io_issue_sqe(req, NULL, &nxt, false);
@@ -4950,6 +4945,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
        for (i = 0; i < nr; i++) {
                const struct io_uring_sqe *sqe;
                struct io_kiocb *req;
+               int err;
 
                req = io_get_req(ctx, statep);
                if (unlikely(!req)) {
@@ -4966,20 +4962,23 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
                submitted++;
 
                if (unlikely(req->opcode >= IORING_OP_LAST)) {
-                       io_cqring_add_event(req, -EINVAL);
+                       err = -EINVAL;
+fail_req:
+                       io_cqring_add_event(req, err);
                        io_double_put_req(req);
                        break;
                }
 
                if (io_op_defs[req->opcode].needs_mm && !*mm) {
                        mm_fault = mm_fault || !mmget_not_zero(ctx->sqo_mm);
-                       if (!mm_fault) {
-                               use_mm(ctx->sqo_mm);
-                               *mm = ctx->sqo_mm;
+                       if (unlikely(mm_fault)) {
+                               err = -EFAULT;
+                               goto fail_req;
                        }
+                       use_mm(ctx->sqo_mm);
+                       *mm = ctx->sqo_mm;
                }
 
-               req->has_user = *mm != NULL;
                req->in_async = async;
                req->needs_fixed_file = async;
                trace_io_uring_submit_sqe(ctx, req->opcode, req->user_data,