Re: [libvirt] [PATCH v3 2/3] qemu_cgroup: Handle device mapper targets properly

4 Apr 2018


      On Tue, Apr 03, 2018 at 11:03:26 +0200, Michal Privoznik wrote:
...
https://bugzilla.redhat.com/show_bug.cgi?id=1557769
Problem with device mapper targets is that there can be several
other devices 'hidden' behind them. For instance, /dev/dm-1 can
consist of /dev/sda, /dev/sdb and /dev/sdc. Therefore, when
setting up devices CGroup and namespaces we have to take this
into account.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---
 libvirt.spec.in        |  2 ++
 src/qemu/qemu_cgroup.c | 69 +++++++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 62 insertions(+), 9 deletions(-)
[...]
...
@@ -71,12 +75,35 @@ qemuSetupImagePathCgroup(virDomainObjPtr vm,
     VIR_DEBUG("Allow path %s, perms: %s",
               path, virCgroupGetDevicePermsString(perms));
-    ret = virCgroupAllowDevicePath(priv->cgroup, path, perms, true);
+    rv = virCgroupAllowDevicePath(priv->cgroup, path, perms, true);
So this returns 1 if 'path' is not a char or block device ...
...
virDomainAuditCgroupPath(vm, priv->cgroup, "allow", path,
                              virCgroupGetDevicePermsString(perms),
-                             ret);
+                             rv);
+    if (rv < 0)
+        goto cleanup;
+    if (virDevMapperGetTargets(path, &targetPaths) < 0 &&
+        errno != ENOSYS && errno != EBADF) {
+        virReportSystemError(errno,
So in that case this is definitely not necessary and should be skipped.

    

Peter Krempa