[PATCH] ublk: check for unprivileged daemon on each I/O fetch

[Caleb Sander Mateos <csander@purestorage.com>]

Commit ab03a61c6614 ("ublk: have a per-io daemon instead of a per-queue
daemon") allowed each ublk I/O to have an independent daemon task.
However, nr_privileged_daemon is only computed based on whether the last
I/O fetched in each ublk queue has an unprivileged daemon task.
Fix this by checking whether every fetched I/O's daemon is privileged.
Change nr_privileged_daemon from a count of queues to a boolean
indicating whether any I/Os have an unprivileged daemon.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Fixes: ab03a61c6614 ("ublk: have a per-io daemon instead of a per-queue daemon")
---
 drivers/block/ublk_drv.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 6561d2a561fa..a035070dd690 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -233,11 +233,11 @@ struct ublk_device {
 
 	struct ublk_params	params;
 
 	struct completion	completion;
 	unsigned int		nr_queues_ready;
-	unsigned int		nr_privileged_daemon;
+	bool 			unprivileged_daemons;
 	struct mutex cancel_mutex;
 	bool canceling;
 	pid_t 	ublksrv_tgid;
 };
 
@@ -1548,11 +1548,11 @@ static void ublk_reset_ch_dev(struct ublk_device *ub)
 		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_privileged_daemon = 0;
+	ub->unprivileged_daemons = false;
 	ub->ublksrv_tgid = -1;
 }
 
 static struct gendisk *ublk_get_disk(struct ublk_device *ub)
 {
@@ -1978,16 +1978,14 @@ static void ublk_reset_io_flags(struct ublk_device *ub)
 /* device can only be started after all IOs are ready */
 static void ublk_mark_io_ready(struct ublk_device *ub, struct ublk_queue *ubq)
 	__must_hold(&ub->mutex)
 {
 	ubq->nr_io_ready++;
-	if (ublk_queue_ready(ubq)) {
+	if (ublk_queue_ready(ubq))
 		ub->nr_queues_ready++;
-
-		if (capable(CAP_SYS_ADMIN))
-			ub->nr_privileged_daemon++;
-	}
+	if (!ub->unprivileged_daemons && !capable(CAP_SYS_ADMIN))
+		ub->unprivileged_daemons = true;
 
 	if (ub->nr_queues_ready == ub->dev_info.nr_hw_queues) {
 		/* now we are ready for handling ublk io request */
 		ublk_reset_io_flags(ub);
 		complete_all(&ub->completion);
@@ -2878,12 +2876,12 @@ static int ublk_ctrl_start_dev(struct ublk_device *ub,
 	ub->dev_info.ublksrv_pid = ublksrv_pid;
 	ub->ub_disk = disk;
 
 	ublk_apply_params(ub);
 
-	/* don't probe partitions if any one ubq daemon is un-trusted */
-	if (ub->nr_privileged_daemon != ub->nr_queues_ready)
+	/* don't probe partitions if any daemon task is un-trusted */
+	if (ub->unprivileged_daemons)
 		set_bit(GD_SUPPRESS_PART_SCAN, &disk->state);
 
 	ublk_get_device(ub);
 	ub->dev_info.state = UBLK_S_DEV_LIVE;
 
-- 
2.45.2