We have to add each submitted polled request to the io_ring_ctx
poll_submitted list, which means we have to grab the poll_lock. We
already use the block plug to batch submissions if we're doing a batch
of IO submissions, extend that to cover the poll requests internally as
well.
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
fs/io_uring.c | 121 +++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 106 insertions(+), 15 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index fb1b04ccc12a..62f31f20f3d5 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -126,6 +126,21 @@ struct io_kiocb {
#define IO_PLUG_THRESHOLD 2
#define IO_IOPOLL_BATCH 8
+struct io_submit_state {
+ struct io_ring_ctx *ctx;
+
+ struct blk_plug plug;
+#ifdef CONFIG_BLOCK
+ struct blk_plug_cb plug_cb;
+#endif
+
+ /*
+ * Polled iocbs that have been submitted, but not added to the ctx yet
+ */
+ struct list_multi req_list;
+ unsigned int req_count;
+};
+
static struct kmem_cache *req_cachep;
static const struct file_operations io_uring_fops;
@@ -288,6 +303,12 @@ static void io_multi_list_add(struct io_kiocb *req, struct list_multi *list)
list_add_tail(&req->list, &list->list);
}
+static void io_multi_list_splice(struct list_multi *src, struct list_multi *dst)
+{
+ list_splice_tail_init(&src->list, &dst->list);
+ dst->multi |= src->multi;
+}
+
/*
* Find and free completed poll iocbs
*/
@@ -459,17 +480,46 @@ static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2)
}
}
+/*
+ * Called either at the end of IO submission, or through a plug callback
+ * because we're going to schedule. Moves out local batch of requests to
+ * the ctx poll list, so they can be found for polling + reaping.
+ */
+static void io_flush_state_reqs(struct io_ring_ctx *ctx,
+ struct io_submit_state *state)
+{
+ io_multi_list_splice(&state->req_list, &ctx->poll_list);
+ state->req_count = 0;
+}
+
+static void io_iopoll_req_add_list(struct io_kiocb *req)
+{
+ struct io_ring_ctx *ctx = req->ctx;
+
+ io_multi_list_add(req, &ctx->poll_list);
+}
+
+static void io_iopoll_req_add_state(struct io_submit_state *state,
+ struct io_kiocb *req)
+{
+ io_multi_list_add(req, &state->req_list);
+ if (++state->req_count >= IO_IOPOLL_BATCH)
+ io_flush_state_reqs(state->ctx, state);
+}
+
/*
* After the iocb has been issued, it's safe to be found on the poll list.
* Adding the kiocb to the list AFTER submission ensures that we don't
* find it from a io_getevents() thread before the issuer is done accessing
* the kiocb cookie.
*/
-static void io_iopoll_req_issued(struct io_kiocb *req)
+static void io_iopoll_req_issued(struct io_submit_state *state,
+ struct io_kiocb *req)
{
- struct io_ring_ctx *ctx = req->ctx;
-
- io_multi_list_add(req, &ctx->poll_list);
+ if (!state || !IS_ENABLED(CONFIG_BLOCK))
+ io_iopoll_req_add_list(req);
+ else
+ io_iopoll_req_add_state(state, req);
}
static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
@@ -701,7 +751,8 @@ static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe,
}
static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
- struct sqe_submit *s, bool force_nonblock)
+ struct sqe_submit *s, bool force_nonblock,
+ struct io_submit_state *state)
{
const struct io_uring_sqe *sqe = s->sqe;
ssize_t ret;
@@ -739,7 +790,7 @@ static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
if (ctx->flags & IORING_SETUP_IOPOLL) {
if (req->flags & REQ_F_IOPOLL_EAGAIN)
return -EAGAIN;
- io_iopoll_req_issued(req);
+ io_iopoll_req_issued(state, req);
}
return 0;
@@ -771,7 +822,7 @@ static void io_sq_wq_submit_work(struct work_struct *work)
use_mm(ctx->sqo_mm);
set_fs(USER_DS);
- ret = __io_submit_sqe(ctx, req, &req->work.submit, false);
+ ret = __io_submit_sqe(ctx, req, &req->work.submit, false, NULL);
set_fs(old_fs);
unuse_mm(ctx->sqo_mm);
@@ -784,7 +835,8 @@ static void io_sq_wq_submit_work(struct work_struct *work)
current->files = old_files;
}
-static int io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s)
+static int io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s,
+ struct io_submit_state *state)
{
struct io_kiocb *req;
ssize_t ret;
@@ -793,7 +845,7 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s)
if (unlikely(!req))
return -EAGAIN;
- ret = __io_submit_sqe(ctx, req, s, true);
+ ret = __io_submit_sqe(ctx, req, s, true, state);
if (ret == -EAGAIN) {
memcpy(&req->work.submit, s, sizeof(*s));
INIT_WORK(&req->work.work, io_sq_wq_submit_work);
@@ -806,6 +858,43 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s)
return ret;
}
+#ifdef CONFIG_BLOCK
+static void io_state_unplug(struct blk_plug_cb *cb, bool from_schedule)
+{
+ struct io_submit_state *state;
+
+ state = container_of(cb, struct io_submit_state, plug_cb);
+ if (!list_empty(&state->req_list.list))
+ io_flush_state_reqs(state->ctx, state);
+}
+#endif
+
+/*
+ * Batched submission is done, ensure local IO is flushed out.
+ */
+static void io_submit_state_end(struct io_submit_state *state)
+{
+ blk_finish_plug(&state->plug);
+ if (!list_empty(&state->req_list.list))
+ io_flush_state_reqs(state->ctx, state);
+}
+
+/*
+ * Start submission side cache.
+ */
+static void io_submit_state_start(struct io_submit_state *state,
+ struct io_ring_ctx *ctx)
+{
+ state->ctx = ctx;
+ INIT_LIST_HEAD(&state->req_list.list);
+ state->req_count = 0;
+#ifdef CONFIG_BLOCK
+ state->plug_cb.callback = io_state_unplug;
+ blk_start_plug(&state->plug);
+ list_add(&state->plug_cb.list, &state->plug.cb_list);
+#endif
+}
+
static void io_inc_sqring(struct io_ring_ctx *ctx)
{
struct io_sq_ring *ring = ctx->sq_ring;
@@ -840,11 +929,13 @@ static bool io_peek_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s)
static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
{
+ struct io_submit_state state, *statep = NULL;
int i, ret = 0, submit = 0;
- struct blk_plug plug;
- if (to_submit > IO_PLUG_THRESHOLD)
- blk_start_plug(&plug);
+ if (to_submit > IO_PLUG_THRESHOLD) {
+ io_submit_state_start(&state, ctx);
+ statep = &state;
+ }
for (i = 0; i < to_submit; i++) {
struct sqe_submit s;
@@ -852,7 +943,7 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
if (!io_peek_sqring(ctx, &s))
break;
- ret = io_submit_sqe(ctx, &s);
+ ret = io_submit_sqe(ctx, &s, statep);
if (ret)
break;
@@ -860,8 +951,8 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
io_inc_sqring(ctx);
}
- if (to_submit > IO_PLUG_THRESHOLD)
- blk_finish_plug(&plug);
+ if (statep)
+ io_submit_state_end(statep);
return submit ? submit : ret;
}
--
2.17.1
