io_uring: iterate req cache backwards

Grab requests from cache-array from the end, so can get by only
free_reqs.

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 1580f1e7ba1c7a48432ea58d9d92342ec2ef2dcb..42b45c57c3f8561579d95e284c8480d80d6fa363 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -585,8 +585,7 @@ struct io_submit_state {
         * io_kiocb alloc cache
         */
        void                    *reqs[IO_IOPOLL_BATCH];
-       unsigned                int free_reqs;
-       unsigned                int cur_req;
+       unsigned int            free_reqs;
 
        /*
         * File reference cache
@@ -1190,12 +1189,10 @@ static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx,
                        ret = 1;
                }
                state->free_reqs = ret - 1;
-               state->cur_req = 1;
-               req = state->reqs[0];
+               req = state->reqs[ret - 1];
        } else {
-               req = state->reqs[state->cur_req];
                state->free_reqs--;
-               state->cur_req++;
+               req = state->reqs[state->free_reqs];
        }
 
 got_it:
@@ -4849,8 +4846,7 @@ static void io_submit_state_end(struct io_submit_state *state)
        blk_finish_plug(&state->plug);
        io_file_put(state);
        if (state->free_reqs)
-               kmem_cache_free_bulk(req_cachep, state->free_reqs,
-                                       &state->reqs[state->cur_req]);
+               kmem_cache_free_bulk(req_cachep, state->free_reqs, state->reqs);
 }
 
 /*