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