On Fri, Aug 08, 2025 at 09:52:15AM -0600, Caleb Sander Mateos wrote:
> 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@xxxxxxxxxxxxxxx>
> Fixes: ab03a61c6614 ("ublk: have a per-io daemon instead of a per-queue daemon")
Nice catch!
> ---
> 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;
Shorter:
ub->unprivileged_daemons |= !capable(CAP_SYS_ADMIN);
>
> 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
>
