Mark the plug with nowait == true, which will cause requests to avoid
blocking on request allocation. If they do, we catch them and add them
to the plug list. Once we finish the plug, re-issue requests that got
caught.
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
Since v1:
- Properly re-prep on resubmit
- Sanity check for io_wq_current_is_worker()
- Sanity check we're just doing read/write for re-issue
- Ensure iov state is sane for resubmit
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 625578715d37..942984bda2f8 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1947,12 +1947,31 @@ static void io_complete_rw_common(struct kiocb *kiocb, long res)
__io_cqring_add_event(req, res, cflags);
}
+static bool io_rw_reissue(struct io_kiocb *req, long res)
+{
+#ifdef CONFIG_BLOCK
+ struct blk_plug *plug;
+
+ if ((res != -EAGAIN && res != -EOPNOTSUPP) || io_wq_current_is_worker())
+ return false;
+
+ plug = current->plug;
+ if (plug && plug->nowait) {
+ list_add_tail(&req->list, &plug->nowait_list);
+ return true;
+ }
+#endif
+ return false;
+}
+
static void io_complete_rw(struct kiocb *kiocb, long res, long res2)
{
struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw.kiocb);
- io_complete_rw_common(kiocb, res);
- io_put_req(req);
+ if (!io_rw_reissue(req, res)) {
+ io_complete_rw_common(kiocb, res);
+ io_put_req(req);
+ }
}
static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2)
@@ -2629,6 +2648,7 @@ static int io_read(struct io_kiocb *req, bool force_nonblock)
iov_count = iov_iter_count(&iter);
ret = rw_verify_area(READ, req->file, &kiocb->ki_pos, iov_count);
if (!ret) {
+ unsigned long nr_segs = iter.nr_segs;
ssize_t ret2 = 0;
if (req->file->f_op->read_iter)
@@ -2640,6 +2660,8 @@ static int io_read(struct io_kiocb *req, bool force_nonblock)
if (!force_nonblock || (ret2 != -EAGAIN && ret2 != -EIO)) {
kiocb_done(kiocb, ret2);
} else {
+ iter.count = iov_count;
+ iter.nr_segs = nr_segs;
copy_iov:
ret = io_setup_async_rw(req, io_size, iovec,
inline_vecs, &iter);
@@ -2726,6 +2748,7 @@ static int io_write(struct io_kiocb *req, bool force_nonblock)
iov_count = iov_iter_count(&iter);
ret = rw_verify_area(WRITE, req->file, &kiocb->ki_pos, iov_count);
if (!ret) {
+ unsigned long nr_segs = iter.nr_segs;
ssize_t ret2;
/*
@@ -2763,6 +2786,8 @@ static int io_write(struct io_kiocb *req, bool force_nonblock)
if (!force_nonblock || ret2 != -EAGAIN) {
kiocb_done(kiocb, ret2);
} else {
+ iter.count = iov_count;
+ iter.nr_segs = nr_segs;
copy_iov:
ret = io_setup_async_rw(req, io_size, iovec,
inline_vecs, &iter);
@@ -5789,12 +5814,70 @@ static int io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
return 0;
}
+#ifdef CONFIG_BLOCK
+static bool io_resubmit_prep(struct io_kiocb *req)
+{
+ struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
+ struct iov_iter iter;
+ ssize_t ret;
+ int rw;
+
+ switch (req->opcode) {
+ case IORING_OP_READV:
+ case IORING_OP_READ_FIXED:
+ case IORING_OP_READ:
+ rw = READ;
+ break;
+ case IORING_OP_WRITEV:
+ case IORING_OP_WRITE_FIXED:
+ case IORING_OP_WRITE:
+ rw = WRITE;
+ break;
+ default:
+ printk_once(KERN_WARNING "io_uring: bad opcode in resubmit %d\n",
+ req->opcode);
+ goto end_req;
+ }
+
+ ret = io_import_iovec(rw, req, &iovec, &iter, false);
+ if (ret < 0)
+ goto end_req;
+ ret = io_setup_async_rw(req, ret, iovec, inline_vecs, &iter);
+ if (!ret)
+ return true;
+ kfree(iovec);
+end_req:
+ io_cqring_add_event(req, ret);
+ req_set_fail_links(req);
+ io_put_req(req);
+ return false;
+}
+
+static void io_resubmit_rw(struct list_head *list)
+{
+ struct io_kiocb *req;
+
+ while (!list_empty(list)) {
+ req = list_first_entry(list, struct io_kiocb, list);
+ list_del(&req->list);
+ if (io_resubmit_prep(req)) {
+ refcount_inc(&req->refs);
+ io_queue_async_work(req);
+ }
+ }
+}
+#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);
+#ifdef CONFIG_BLOCK
+ if (unlikely(!list_empty(&state->plug.nowait_list)))
+ io_resubmit_rw(&state->plug.nowait_list);
+#endif
io_state_file_put(state);
if (state->free_reqs)
kmem_cache_free_bulk(req_cachep, state->free_reqs, state->reqs);
@@ -5807,6 +5890,10 @@ static void io_submit_state_start(struct io_submit_state *state,
unsigned int max_ios)
{
blk_start_plug(&state->plug);
+#ifdef CONFIG_BLOCK
+ INIT_LIST_HEAD(&state->plug.nowait_list);
+ state->plug.nowait = true;
+#endif
state->free_reqs = 0;
state->file = NULL;
state->ios_left = max_ios;
--
Jens Axboe
