[PATCH 11/12] io_uring: refactor io_req_defer()

Pavel Begunkov
2021-06-14T22:38:05Z

Rename io_req_defer() into io_drain_req() and refactor it uncoupling it
from io_queue_sqe() error handling and preparing for coming
optimisations. Also, prioritise non IOSQE_ASYNC path.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
fs/io_uring.c | 39 +++++++++++++++++++--------------------
1 file changed, 19 insertions(+), 20 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 1b6cfc6b79c5..29b705201ca3 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5998,7 +5998,7 @@ static u32 io_get_sequence(struct io_kiocb *req)
return ctx->cached_sq_head - nr_reqs;
}

-static int io_req_defer(struct io_kiocb *req)
+static bool io_drain_req(struct io_kiocb *req)
{
struct io_ring_ctx *ctx = req->ctx;
struct io_defer_entry *de;
@@ -6008,27 +6008,29 @@ static int io_req_defer(struct io_kiocb *req)
/* Still need defer if there is pending req in defer list. */
if (likely(list_empty_careful(&ctx->defer_list) &&
!(req->flags & REQ_F_IO_DRAIN)))
- return 0;
+ return false;

seq = io_get_sequence(req);
/* Still a chance to pass the sequence check */
if (!req_need_defer(req, seq) && list_empty_careful(&ctx->defer_list))
- return 0;
+ return false;

ret = io_req_prep_async(req);
if (ret)
return ret;
io_prep_async_link(req);
de = kmalloc(sizeof(*de), GFP_KERNEL);
- if (!de)
- return -ENOMEM;
+ if (!de) {
+ io_req_complete_failed(req, ret);
+ return true;
+ }

spin_lock_irq(&ctx->completion_lock);
if (!req_need_defer(req, seq) && list_empty(&ctx->defer_list)) {
spin_unlock_irq(&ctx->completion_lock);
kfree(de);
io_queue_async_work(req);
- return -EIOCBQUEUED;
+ return true;
}

trace_io_uring_defer(ctx, req, req->user_data);
@@ -6036,7 +6038,7 @@ static int io_req_defer(struct io_kiocb *req)
de->seq = seq;
list_add_tail(&de->list, &ctx->defer_list);
spin_unlock_irq(&ctx->completion_lock);
- return -EIOCBQUEUED;
+ return true;
}

static void io_clean_op(struct io_kiocb *req)
@@ -6447,21 +6449,18 @@ static void __io_queue_sqe(struct io_kiocb *req)

static void io_queue_sqe(struct io_kiocb *req)
{
- int ret;
+ if (io_drain_req(req))
+ return;

- ret = io_req_defer(req);
- if (ret) {
- if (ret != -EIOCBQUEUED) {
-fail_req:
- io_req_complete_failed(req, ret);
- }
- } else if (req->flags & REQ_F_FORCE_ASYNC) {
- ret = io_req_prep_async(req);
- if (unlikely(ret))
- goto fail_req;
- io_queue_async_work(req);
- } else {
+ if (likely(!(req->flags & REQ_F_FORCE_ASYNC))) {
__io_queue_sqe(req);
+ } else {
+ int ret = io_req_prep_async(req);
+
+ if (unlikely(ret))
+ io_req_complete_failed(req, ret);
+ else
+ io_queue_async_work(req);
}
}

--
2.31.1