Linux list all IROs currently in use

To list all the I/O requestors (IROs) currently in use on a Linux system, you can use the lsblk command with the -r option.

lsblk -r

The output will list all the block devices on the system, along with their IROs. The IROs are listed in the IRO column.

For example:

$ lsblk -r
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT IRO
sda      8:0    0  75.2G  0 disk 
├─sda1   8:1    0  74.2G  0 part /          0
└─sda2   8:2    0   100M  0 part /boot/efi  0
sdb      8:16   0 931.5G  0 disk 
└─sdb1   8:17   0 931.5G  0 part /mnt/hdd   1
sdc      8:32   0 931.5G  0 disk 
└─sdc1   8:33   0 931.5G  0 part /mnt/hdd2  2

In this example, the block devices sdb1 and sdc1 have IROs 1 and 2, respectively.