io_uring: force_nonspin

We don't really need to pass the number of requests to complete into
io_do_iopoll(), a flag whether to enforce non-spin mode is enough.

Should be straightforward, maybe except io_iopoll_check(). We pass !min
there, because we do never enter with the number of already reaped
requests is larger than the specified @min, apart from the first
iteration, where nr_events is 0 and so the final check should be
identical.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/782b39d1d8ec584eae15bca0a1feb6f0571fe5b8.1632516769.git.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 bda302b..d605954 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2453,7 +2453,7 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
 }
 
 static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
-                       long min)
+                       bool force_nonspin)
 {
        struct io_kiocb *req, *tmp;
        unsigned int poll_flags = BLK_POLL_NOSLEEP;
@@ -2462,9 +2462,9 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
 
        /*
         * Only spin for completions if we don't have multiple devices hanging
-        * off our complete list, and we're under the requested amount.
+        * off our complete list.
         */
-       if (ctx->poll_multi_queue || *nr_events >= min)
+       if (ctx->poll_multi_queue || force_nonspin)
                poll_flags |= BLK_POLL_ONESHOT;
 
        list_for_each_entry_safe(req, tmp, &ctx->iopoll_list, inflight_entry) {
@@ -2516,7 +2516,7 @@ static void io_iopoll_try_reap_events(struct io_ring_ctx *ctx)
        while (!list_empty(&ctx->iopoll_list)) {
                unsigned int nr_events = 0;
 
-               io_do_iopoll(ctx, &nr_events, 0);
+               io_do_iopoll(ctx, &nr_events, true);
 
                /* let it sleep and repeat later if can't complete a request */
                if (nr_events == 0)
@@ -2578,7 +2578,7 @@ static int io_iopoll_check(struct io_ring_ctx *ctx, long min)
                            list_empty(&ctx->iopoll_list))
                                break;
                }
-               ret = io_do_iopoll(ctx, &nr_events, min);
+               ret = io_do_iopoll(ctx, &nr_events, !min);
        } while (!ret && nr_events < min && !need_resched());
 out:
        mutex_unlock(&ctx->uring_lock);
@@ -7347,7 +7347,7 @@ static int __io_sq_thread(struct io_ring_ctx *ctx, bool cap_entries)
 
                mutex_lock(&ctx->uring_lock);
                if (!list_empty(&ctx->iopoll_list))
-                       io_do_iopoll(ctx, &nr_events, 0);
+                       io_do_iopoll(ctx, &nr_events, true);
 
                /*
                 * Don't submit if refs are dying, good for io_uring_register(),