On 11/16/20 3:22 PM, Zihao Chang wrote:
Hi all,When using qemu-pr-helper，"sg_persist" in guest return Aborted Command after iscsiadm logout & login. My confusion: Is this problem caused by bugs of libvirt/qemu-pr-helper? Or iscsiadm logout & login should be forbidden when using qemu-pr-helper? Or There is something wrong with my config. Steps to Reproduce: 1. setup multipath env 1) set /etc/iscsi/initiatorname.iscsi 2) iscsiadm discovery & login 3) start multipathd 2. add the following xml to guest <disk type='block' device='lun'> <driver name='qemu' type='raw' cache='none' io='native'/> <source dev='/dev/mapper/XXXXXXXXXXXXXXXXX'> **<reservations managed='yes'/>** </source> <target dev='sdc' bus='scsi'/> </disk> 3. start the guest 1) "sg_persist -v -i -n -k -d /dev/sdc" works well in the guest 2) here /dev/sdc(guest) -> /dev/sdht(host) 4. iscsiadm logout & login on host 1) iscsiadm -m node -u (host) 2) iscsiadm -m node -l (host) 3) here /dev/sdc(guest) -(change)-> /dev/sdfo(host) 5. exec "sg_persist -v -i -n -k -d /dev/sdc" in the guest 1) command return: Persistent Reservation In cmd: 5e 00 00 00 00 00 00 20 00 00 persistent reservation in: Fixed format, current; Sense key: Aborted Command Additional sense: Logical unit communication failure PR in (Read keys): Aborted command sense key, other than protection related (asc=0x10) 2) strace qemu-pr-helper show: openat(AT_FDCWD, "/dev/sdht", O_RDONLY) = -1 ENOENT (No such file or directory) Additional info: 1. strace qemu-pr-helper show: openat(AT_FDCWD, "/dev/sdht", O_RDONLY) = -1 ENOENT (No such file or directory) 2. This problem may be related to mnt(namespace). I try to set mnt of qemu-pr-helper as pid 1, sg_persist works well after logout & login.
Yeah, this smells like a libvirt bug. But I'm not sure how to solve it. Because from security POV we want to run qemu-pr-helper inside the same namespace as qemu is running (so that it doesn't see more devices than needed). But at the same time, when a /dev node changes from outside libvirt does not reflect that in the namespace.
BTW: is /dev/mapper/XXX updated on re-login? Becuase if not, then you'd get the same error in qemu, if it wasn't for pr-helper hitting the issue first.
A possible work around might be to use unmanaged pr-helper (reservations managed='no') and just start it by hand.
Michal
