selftests: ublk: kublk: tie sqe allocation to io instead of queue

We currently have a helper ublk_queue_alloc_sqes which the ublk targets
use to allocate SQEs for their own operations. However, as we move
towards decoupled ublk_queues and ublk server threads, this helper does
not make sense anymore. SQEs are allocated from rings, and we will have
one ring per thread to avoid locking. Change the SQE allocation helper
to ublk_io_alloc_sqes. Currently this still allocates SQEs from the io's
queue's ring, but when we fully decouple threads and queues, it will
allocate from the io's thread's ring instead.

Signed-off-by: Uday Shankar <[email protected]>
Reviewed-by: Ming Lei <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

Author: ps-ushankar

tools/testing/selftests/ublk/fault_inject.c

@@ -46,7 +46,7 @@ static int ublk_fault_inject_queue_io(struct ublk_queue *q, int tag)
 		.tv_nsec = (long long)q->dev->private_data,
 	};
 
-	ublk_queue_alloc_sqes(q, &sqe, 1);
+	ublk_io_alloc_sqes(ublk_get_io(q, tag), &sqe, 1);
 	io_uring_prep_timeout(sqe, &ts, 1, 0);
 	sqe->user_data = build_user_data(tag, ublksrv_get_op(iod), 0, q->q_id, 1);
 

tools/testing/selftests/ublk/file_backed.c

@@ -18,7 +18,7 @@ static int loop_queue_flush_io(struct ublk_queue *q, const struct ublksrv_io_des
 	unsigned ublk_op = ublksrv_get_op(iod);
 	struct io_uring_sqe *sqe[1];
 
-	ublk_queue_alloc_sqes(q, sqe, 1);
+	ublk_io_alloc_sqes(ublk_get_io(q, tag), sqe, 1);
 	io_uring_prep_fsync(sqe[0], 1 /*fds[1]*/, IORING_FSYNC_DATASYNC);
 	io_uring_sqe_set_flags(sqe[0], IOSQE_FIXED_FILE);
 	/* bit63 marks us as tgt io */
@@ -36,7 +36,7 @@ static int loop_queue_tgt_rw_io(struct ublk_queue *q, const struct ublksrv_io_de
 	void *addr = (zc | auto_zc) ? NULL : (void *)iod->addr;
 
 	if (!zc || auto_zc) {
-		ublk_queue_alloc_sqes(q, sqe, 1);
+		ublk_io_alloc_sqes(ublk_get_io(q, tag), sqe, 1);
 		if (!sqe[0])
 			return -ENOMEM;
 
@@ -52,7 +52,7 @@ static int loop_queue_tgt_rw_io(struct ublk_queue *q, const struct ublksrv_io_de
 		return 1;
 	}
 
-	ublk_queue_alloc_sqes(q, sqe, 3);
+	ublk_io_alloc_sqes(ublk_get_io(q, tag), sqe, 3);
 
 	io_uring_prep_buf_register(sqe[0], 0, tag, q->q_id, tag);
 	sqe[0]->flags |= IOSQE_CQE_SKIP_SUCCESS | IOSQE_IO_HARDLINK;

tools/testing/selftests/ublk/kublk.c

@@ -599,7 +599,7 @@ int ublk_queue_io_cmd(struct ublk_queue *q, struct ublk_io *io, unsigned tag)
 	if (io_uring_sq_space_left(&q->ring) < 1)
 		io_uring_submit(&q->ring);
 
-	ublk_queue_alloc_sqes(q, sqe, 1);
+	ublk_io_alloc_sqes(ublk_get_io(q, tag), sqe, 1);
 	if (!sqe[0]) {
 		ublk_err("%s: run out of sqe %d, tag %d\n",
 				__func__, q->q_id, tag);

tools/testing/selftests/ublk/kublk.h

@@ -124,6 +124,8 @@ struct ublk_io {
 	unsigned short flags;
 	unsigned short refs;		/* used by target code only */
 
+	int tag;
+
 	int result;
 
 	unsigned short tgt_ios;
@@ -289,17 +291,23 @@ static inline void ublk_dbg(int level, const char *fmt, ...)
 	}
 }
 
-static inline int ublk_queue_alloc_sqes(struct ublk_queue *q,
+static inline struct ublk_queue *ublk_io_to_queue(const struct ublk_io *io)
+{
+	return container_of(io, struct ublk_queue, ios[io->tag]);
+}
+
+static inline int ublk_io_alloc_sqes(struct ublk_io *io,
 		struct io_uring_sqe *sqes[], int nr_sqes)
 {
-	unsigned left = io_uring_sq_space_left(&q->ring);
+	struct io_uring *ring = &ublk_io_to_queue(io)->ring;
+	unsigned left = io_uring_sq_space_left(ring);
 	int i;
 
 	if (left < nr_sqes)
-		io_uring_submit(&q->ring);
+		io_uring_submit(ring);
 
 	for (i = 0; i < nr_sqes; i++) {
-		sqes[i] = io_uring_get_sqe(&q->ring);
+		sqes[i] = io_uring_get_sqe(ring);
 		if (!sqes[i])
 			return i;
 	}

tools/testing/selftests/ublk/null.c

@@ -60,7 +60,7 @@ static int null_queue_zc_io(struct ublk_queue *q, int tag)
 	const struct ublksrv_io_desc *iod = ublk_get_iod(q, tag);
 	struct io_uring_sqe *sqe[3];
 
-	ublk_queue_alloc_sqes(q, sqe, 3);
+	ublk_io_alloc_sqes(ublk_get_io(q, tag), sqe, 3);
 
 	io_uring_prep_buf_register(sqe[0], 0, tag, q->q_id, tag);
 	sqe[0]->user_data = build_user_data(tag,
@@ -82,7 +82,7 @@ static int null_queue_auto_zc_io(struct ublk_queue *q, int tag)
 	const struct ublksrv_io_desc *iod = ublk_get_iod(q, tag);
 	struct io_uring_sqe *sqe[1];
 
-	ublk_queue_alloc_sqes(q, sqe, 1);
+	ublk_io_alloc_sqes(ublk_get_io(q, tag), sqe, 1);
 	__setup_nop_io(tag, iod, sqe[0], q->q_id);
 	return 1;
 }

tools/testing/selftests/ublk/stripe.c

@@ -138,7 +138,7 @@ static int stripe_queue_tgt_rw_io(struct ublk_queue *q, const struct ublksrv_io_
 	io->private_data = s;
 	calculate_stripe_array(conf, iod, s, base);
 
-	ublk_queue_alloc_sqes(q, sqe, s->nr + extra);
+	ublk_io_alloc_sqes(ublk_get_io(q, tag), sqe, s->nr + extra);
 
 	if (zc) {
 		io_uring_prep_buf_register(sqe[0], 0, tag, q->q_id, tag);
@@ -182,7 +182,7 @@ static int handle_flush(struct ublk_queue *q, const struct ublksrv_io_desc *iod,
 	struct io_uring_sqe *sqe[NR_STRIPE];
 	int i;
 
-	ublk_queue_alloc_sqes(q, sqe, conf->nr_files);
+	ublk_io_alloc_sqes(ublk_get_io(q, tag), sqe, conf->nr_files);
 	for (i = 0; i < conf->nr_files; i++) {
 		io_uring_prep_fsync(sqe[i], i + 1, IORING_FSYNC_DATASYNC);
 		io_uring_sqe_set_flags(sqe[i], IOSQE_FIXED_FILE);