From a6cfd2e03c77fb54c384d66681900e32a80efdb7 Mon Sep 17 00:00:00 2001
Message-Id: <a6cfd2e03c77fb54c384d66681900e32a80efdb7@dist-git>
From: Michal Privoznik <mprivozn@redhat.com>
Date: Mon, 11 May 2020 16:40:11 +0200
Subject: [PATCH] virDevMapperGetTargetsImpl: Be tolerant to kernels without DM
 support
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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>
(cherry picked from commit 170d1e31df064108d064910c77f6316eb6726985)

https://bugzilla.redhat.com/show_bug.cgi?id=1823976

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Message-Id: <46a1c183bae2cf5070b54883d7a7540124822049.1589207928.git.mprivozn@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
---
 src/util/virdevmapper.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

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) {
-- 
2.26.2