[libvirt] [PATCH] xen-xs: fix uuid of renamed domain
When the XenStore tdb lives persistently and is not cleared between host
reboots, Xend (version 3.4 and 4.1) re-creates the domain information
located in XenStore below /vm/$UUID. (According to the xen-3.2-commit
hg265950e3df69 to fix a problem when locally migrating a domain to the
host itself.)
When doing so a version number is added to the UUID separated by one
dash, which confuses xenStoreDomainIntroduced(): It iterates over all
domains and tries to lookup all inactive domains using
xenStoreDomainGetUUID(), which fails if the running domain is renamed:
virUUIDParse() fails to parse the versioned UUID and the domain is
flagged as missing. When this happens the function delays .2s and
re-tries 20 times again, multiplied by the number of renamed VMs.
14:48:38.878: 4285: debug : xenStoreDomainIntroduced:1354 : Some domains were missing,
trying again
This adds a significant delay:
# time virsh list >/dev/null
real 0m6.529s
# xenstore-list /vm
00000000-0000-0000-0000-000000000000
00000000-0000-0000-0000-000000000000-1
00000000-0000-0000-0000-000000000000-2
00000000-0000-0000-0000-000000000000-3
00000000-0000-0000-0000-000000000000-4
00000000-0000-0000-0000-000000000000-5
7c06121e-90c3-93d4-0126-50481d485cca
00000000-0000-0000-0000-000000000000-6
00000000-0000-0000-0000-000000000000-7
144ad19d-dfb4-2f80-8045-09196bb8784f
00000000-0000-0000-0000-000000000000-8
144ad19d-dfb4-2f80-8045-09196bb8784f-1
00000000-0000-0000-0000-000000000000-9
00000000-0000-0000-0000-000000000000-10
00000000-0000-0000-0000-000000000000-11
00000000-0000-0000-0000-000000000000-12
00000000-0000-0000-0000-000000000000-13
00000000-0000-0000-0000-000000000000-14
144ad19d-dfb4-2f80-8045-09196bb8784f-2
00000000-0000-0000-0000-000000000000-15
144ad19d-dfb4-2f80-8045-09196bb8784f-3
00000000-0000-0000-0000-000000000000-16
The patch adds truncation of the UUID as read from the XenStore path
before passing it to virUUIDParse().
The same issue is reported at
<http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=666135>
Signed-off-by: Philipp Hahn <hahn(a)univention.de>
---
src/xen/xs_internal.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)
diff --git a/src/xen/xs_internal.c b/src/xen/xs_internal.c
index e56d1a4..cdaef17 100644
--- a/src/xen/xs_internal.c
+++ b/src/xen/xs_internal.c
@@ -1115,8 +1115,11 @@ int xenStoreDomainGetUUID(virConnectPtr conn,
snprintf(prop, 199, "/local/domain/%d/vm", id);
prop[199] = 0;
/* This will return something like
- * /vm/00000000-0000-0000-0000-000000000000 */
+ * /vm/00000000-0000-0000-0000-000000000000[-*] */
uuidstr = xs_read(priv->xshandle, 0, prop, &len);
+ /* Strip optional version suffix when VM was renamed */
+ if (len > 40) /* strlen('/vm/') + VIR_UUID_STRING_BUFLEN -
sizeof('\0') */
+ uuidstr[40] = '\0';
/* remove "/vm/" */
ret = virUUIDParse(uuidstr + 4, uuid);
--
1.7.1