maintaining frontend state in libxl

maintaining frontend state in libxl

[Olaf Hering]

While testing 'xl scsi-detach' I noticed that nothing removes the
frontend directory from xenstore. In the example below
/local/domain/8/device/vscsi/1/vscsi-devs/dev-2 becomes stale. Should xl
actively remove also frontend related entries from xenstore, or is that
all up to the frontend itself?

Later I removed also the dev-3 related entry with 'scsi-detach', and
reattached both devices. The result is that dev-2 and dev-3 are reused
and the frontend worked just fine. So I think this is all just
cosmetics.

Also I think vscsi (and maybe pci) are the only ones affected, other
types will most likely just wipe the entire device from xenstore because
they handle just a single device.


Olaf

root@optiplex:~ # xenstore-ls -f |sort  > 1
root@optiplex:~ # xl scsi-detach fv-13.1-pvscsi 2:0:0:2
root@optiplex:~ # xenstore-ls -f |sort  > 2
root@optiplex:~ # diff -u 1 2
--- 1   2015-05-06 13:11:34.000000000 +0200
+++ 2   2015-05-06 13:11:46.000000000 +0200
@@ -138,11 +138,6 @@
 /local/domain/0/backend/vscsi/8/1/vscsi-devs/dev-1/p-devname = "/dev/shm/Fileio.2.1.link"
 /local/domain/0/backend/vscsi/8/1/vscsi-devs/dev-1/state = "4"
 /local/domain/0/backend/vscsi/8/1/vscsi-devs/dev-1/v-dev = "2:0:0:1"
-/local/domain/0/backend/vscsi/8/1/vscsi-devs/dev-2 = ""
-/local/domain/0/backend/vscsi/8/1/vscsi-devs/dev-2/p-dev = "naa.f3653dd5a6f244b9:2"
-/local/domain/0/backend/vscsi/8/1/vscsi-devs/dev-2/p-devname = "/dev/shm/Fileio.2.2.link"
-/local/domain/0/backend/vscsi/8/1/vscsi-devs/dev-2/state = "4"
-/local/domain/0/backend/vscsi/8/1/vscsi-devs/dev-2/v-dev = "2:0:0:2"
 /local/domain/0/backend/vscsi/8/1/vscsi-devs/dev-3 = ""
 /local/domain/0/backend/vscsi/8/1/vscsi-devs/dev-3/p-dev = "naa.f3653dd5a6f244b9:3"
 /local/domain/0/backend/vscsi/8/1/vscsi-devs/dev-3/p-devname = "/dev/shm/Fileio.2.3.link"
@@ -306,7 +301,7 @@
 /local/domain/8/device/vscsi/1/vscsi-devs/dev-1 = ""
 /local/domain/8/device/vscsi/1/vscsi-devs/dev-1/state = "4"
 /local/domain/8/device/vscsi/1/vscsi-devs/dev-2 = ""
-/local/domain/8/device/vscsi/1/vscsi-devs/dev-2/state = "4"
+/local/domain/8/device/vscsi/1/vscsi-devs/dev-2/state = "6"
 /local/domain/8/device/vscsi/1/vscsi-devs/dev-3 = ""
 /local/domain/8/device/vscsi/1/vscsi-devs/dev-3/state = "4"
 /local/domain/8/device/vscsi/2 = ""