From: Michal Privoznik <mprivozn@redhat.com>
Date: Fri, 13 Jul 2018 12:31:16 +0000 (+0200)
Subject: virDevMapperGetTargetsImpl: Be tolerant to kernels without DM support
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=170d1e31df064108d064910c77f6316eb6726985;p=libvirt.git

virDevMapperGetTargetsImpl: Be tolerant to kernels without DM support

https://bugzilla.redhat.com/show_bug.cgi?id=1591732

If kernel is compiled without CONFIG_BLK_DEV_DM enabled, there is
no /dev/mapper/control device and since dm_task_create() actually
does some ioctl() over it creating a task may fail.
To cope with this handle ENOENT and ENODEV gracefully.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
---

diff --git a/src/util/virdevmapper.c b/src/util/virdevmapper.c
index b365f20145..7da0dba911 100644
--- a/src/util/virdevmapper.c
+++ b/src/util/virdevmapper.c
@@ -87,8 +87,14 @@ virDevMapperGetTargetsImpl(const char *path,
         return ret;
     }
 
-    if (!(dmt = dm_task_create(DM_DEVICE_DEPS)))
+    if (!(dmt = dm_task_create(DM_DEVICE_DEPS))) {
+        if (errno == ENOENT || errno == ENODEV) {
+            /* It's okay. Kernel is probably built without
+             * devmapper support. */
+            ret = 0;
+        }
         return ret;
+    }
 
     if (!dm_task_set_name(dmt, path)) {
         if (errno == ENOENT) {