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

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")
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250808155216.296170-1-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 6b95cf48ae77fff5661f9a7a2c7efdbcbcff7493..99abd67b708bc2f267eb37baa1f6d8e653eba898 100644 (file)
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -235,7 +235,7 @@ struct ublk_device {
 
        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;
@@ -1551,7 +1551,7 @@ static void ublk_reset_ch_dev(struct ublk_device *ub)
        /* 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;
 }
 
@@ -1978,12 +1978,10 @@ 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 */
@@ -2878,8 +2876,8 @@ static int ublk_ctrl_start_dev(struct ublk_device *ub,
 
        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);