ublk_mark_io_ready() tracks whether all the ublk_device's I/Os have been
fetched by incrementing ublk_queue's nr_io_ready count and incrementing
ublk_device's nr_queues_ready count if the whole queue is ready.
Simplify the logic by just tracking the total number of fetched I/Os on
each ublk_device. When this count reaches nr_hw_queues * queue_depth,
the ublk_device is ready to receive I/O.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
---
 drivers/block/ublk_drv.c | 28 ++++++++++++----------------
 1 file changed, 12 insertions(+), 16 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 3cf6d344d1c0..aa64f530d5e9 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -199,11 +199,10 @@ struct ublk_queue {
 	struct ublksrv_io_desc *io_cmd_buf;
 
 	bool force_abort;
 	bool canceling;
 	bool fail_io; /* copy of dev->state == UBLK_S_DEV_FAIL_IO */
-	unsigned short nr_io_ready;	/* how many ios setup */
 	spinlock_t		cancel_lock;
 	struct ublk_device *dev;
 	struct ublk_io ios[];
 };
 
@@ -232,11 +231,11 @@ struct ublk_device {
 	struct mm_struct	*mm;
 
 	struct ublk_params	params;
 
 	struct completion	completion;
-	unsigned int		nr_queues_ready;
+	u32			nr_io_ready;
 	bool 			unprivileged_daemons;
 	struct mutex cancel_mutex;
 	bool canceling;
 	pid_t 	ublksrv_tgid;
 };
@@ -1497,13 +1496,10 @@ static const struct blk_mq_ops ublk_mq_ops = {
 
 static void ublk_queue_reinit(struct ublk_device *ub, struct ublk_queue *ubq)
 {
 	int i;
 
-	/* All old ioucmds have to be completed */
-	ubq->nr_io_ready = 0;
-
 	for (i = 0; i < ubq->q_depth; i++) {
 		struct ublk_io *io = &ubq->ios[i];
 
 		/*
 		 * UBLK_IO_FLAG_CANCELED is kept for avoiding to touch
@@ -1548,11 +1544,11 @@ static void ublk_reset_ch_dev(struct ublk_device *ub)
 	for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
 		ublk_queue_reinit(ub, ublk_get_queue(ub, i));
 
 	/* set to NULL, otherwise new tasks cannot mmap io_cmd_buf */
 	ub->mm = NULL;
-	ub->nr_queues_ready = 0;
+	ub->nr_io_ready = 0;
 	ub->unprivileged_daemons = false;
 	ub->ublksrv_tgid = -1;
 }
 
 static struct gendisk *ublk_get_disk(struct ublk_device *ub)
@@ -1846,13 +1842,15 @@ static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd,
 
 	WARN_ON_ONCE(io->cmd != cmd);
 	ublk_cancel_cmd(ubq, pdu->tag, issue_flags);
 }
 
-static inline bool ublk_queue_ready(struct ublk_queue *ubq)
+static inline bool ublk_dev_ready(const struct ublk_device *ub)
 {
-	return ubq->nr_io_ready == ubq->q_depth;
+	u32 total = (u32)ub->dev_info.nr_hw_queues * ub->dev_info.queue_depth;
+
+	return ub->nr_io_ready == total;
 }
 
 static void ublk_cancel_queue(struct ublk_queue *ubq)
 {
 	int i;
@@ -1972,20 +1970,18 @@ static void ublk_reset_io_flags(struct ublk_device *ub)
 	ublk_set_canceling(ub, false);
 	mutex_unlock(&ub->cancel_mutex);
 }
 
 /* device can only be started after all IOs are ready */
-static void ublk_mark_io_ready(struct ublk_device *ub, struct ublk_queue *ubq)
+static void ublk_mark_io_ready(struct ublk_device *ub)
 	__must_hold(&ub->mutex)
 {
-	ubq->nr_io_ready++;
-	if (ublk_queue_ready(ubq))
-		ub->nr_queues_ready++;
 	if (!ub->unprivileged_daemons && !capable(CAP_SYS_ADMIN))
 		ub->unprivileged_daemons = true;
 
-	if (ub->nr_queues_ready == ub->dev_info.nr_hw_queues) {
+	ub->nr_io_ready++;
+	if (ublk_dev_ready(ub)) {
 		/* now we are ready for handling ublk io request */
 		ublk_reset_io_flags(ub);
 		complete_all(&ub->completion);
 	}
 }
@@ -2187,12 +2183,12 @@ static int ublk_fetch(struct io_uring_cmd *cmd, struct ublk_queue *ubq,
 	 * When handling FETCH command for setting up ublk uring queue,
 	 * ub->mutex is the innermost lock, and we won't block for handling
 	 * FETCH, so it is fine even for IO_URING_F_NONBLOCK.
 	 */
 	mutex_lock(&ub->mutex);
-	/* UBLK_IO_FETCH_REQ is only allowed before queue is setup */
-	if (ublk_queue_ready(ubq)) {
+	/* UBLK_IO_FETCH_REQ is only allowed before dev is setup */
+	if (ublk_dev_ready(ub)) {
 		ret = -EBUSY;
 		goto out;
 	}
 
 	/* allow each command to be FETCHed at most once */
@@ -2207,11 +2203,11 @@ static int ublk_fetch(struct io_uring_cmd *cmd, struct ublk_queue *ubq,
 	ret = ublk_config_io_buf(ubq, io, cmd, buf_addr, NULL);
 	if (ret)
 		goto out;
 
 	WRITE_ONCE(io->task, get_task_struct(current));
-	ublk_mark_io_ready(ub, ubq);
+	ublk_mark_io_ready(ub);
 out:
 	mutex_unlock(&ub->mutex);
 	return ret;
 }
 
-- 
2.45.2