ublk: honor IO_URING_F_NONBLOCK for handling control command

Most of control command handlers may sleep, so return -EAGAIN in case
of IO_URING_F_NONBLOCK to defer the handling into io wq context.

Fixes: 71f28f3136af ("ublk_drv: add io_uring based userspace block driver")
Reported-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230104133235.836536-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index e9de9d846b730359623d5b451015c169937f9685..17b677b5d3b221fac658268958730dbc71dade52 100644 (file)
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -1992,6 +1992,9 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd,
        struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
        int ret = -EINVAL;
 
+       if (issue_flags & IO_URING_F_NONBLOCK)
+               return -EAGAIN;
+
        ublk_ctrl_cmd_dump(cmd);
 
        if (!(issue_flags & IO_URING_F_SQE128))