We have to add each submitted polled request to the io_context
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 | 122 +++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 106 insertions(+), 16 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 02eab2f42c63..9f36eb728208 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -121,6 +121,21 @@ struct io_kiocb {
#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_head req_list;
+ unsigned int req_count;
+};
+
static struct kmem_cache *kiocb_cachep, *ioctx_cachep;
static const struct file_operations io_scqring_fops;
@@ -494,21 +509,29 @@ static inline void io_rw_done(struct kiocb *req, ssize_t ret)
}
/*
- * 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.
+ * 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_iopoll_iocb_issued(struct io_kiocb *kiocb)
+static void io_flush_state_reqs(struct io_ring_ctx *ctx,
+ struct io_submit_state *state)
{
+ spin_lock(&ctx->poll_lock);
+ list_splice_tail_init(&state->req_list, &ctx->poll_submitted);
+ spin_unlock(&ctx->poll_lock);
+ state->req_count = 0;
+}
+
+static void io_iopoll_iocb_add_list(struct io_kiocb *kiocb)
+{
+ const int front = test_bit(KIOCB_F_IOPOLL_COMPLETED, &kiocb->ki_flags);
+ struct io_ring_ctx *ctx = kiocb->ki_ctx;
+
/*
* For fast devices, IO may have already completed. If it has, add
* it to the front so we find it first. We can't add to the poll_done
* list as that's unlocked from the completion side.
*/
- const int front = test_bit(KIOCB_F_IOPOLL_COMPLETED, &kiocb->ki_flags);
- struct io_ring_ctx *ctx = kiocb->ki_ctx;
-
spin_lock(&ctx->poll_lock);
if (front)
list_add(&kiocb->ki_list, &ctx->poll_submitted);
@@ -517,6 +540,33 @@ static void io_iopoll_iocb_issued(struct io_kiocb *kiocb)
spin_unlock(&ctx->poll_lock);
}
+static void io_iopoll_iocb_add_state(struct io_submit_state *state,
+ struct io_kiocb *kiocb)
+{
+ if (test_bit(KIOCB_F_IOPOLL_COMPLETED, &kiocb->ki_flags))
+ list_add(&kiocb->ki_list, &state->req_list);
+ else
+ list_add_tail(&kiocb->ki_list, &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_iocb_issued(struct io_submit_state *state,
+ struct io_kiocb *kiocb)
+{
+ if (!state || !IS_ENABLED(CONFIG_BLOCK))
+ io_iopoll_iocb_add_list(kiocb);
+ else
+ io_iopoll_iocb_add_state(state, kiocb);
+}
+
static ssize_t io_read(struct io_kiocb *kiocb, const struct io_uring_iocb *iocb)
{
struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
@@ -632,7 +682,8 @@ static int io_fsync(struct fsync_iocb *req, const struct io_uring_iocb *iocb,
static int __io_submit_one(struct io_ring_ctx *ctx,
const struct io_uring_iocb *iocb,
- unsigned long ki_index)
+ unsigned long ki_index,
+ struct io_submit_state *state)
{
struct io_kiocb *req;
ssize_t ret;
@@ -684,7 +735,7 @@ static int __io_submit_one(struct io_ring_ctx *ctx,
ret = -EAGAIN;
goto out_put_req;
}
- io_iopoll_iocb_issued(req);
+ io_iopoll_iocb_issued(state, req);
}
return 0;
out_put_req:
@@ -692,6 +743,43 @@ static int __io_submit_one(struct io_ring_ctx *ctx,
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))
+ 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))
+ 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);
+ 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.ring;
@@ -726,11 +814,13 @@ static const struct io_uring_iocb *io_peek_sqring(struct io_ring_ctx *ctx,
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++) {
const struct io_uring_iocb *iocb;
@@ -740,7 +830,7 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
if (!iocb)
break;
- ret = __io_submit_one(ctx, iocb, iocb_index);
+ ret = __io_submit_one(ctx, iocb, iocb_index, statep);
if (ret)
break;
@@ -748,8 +838,8 @@ 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
