When setting up mount namespace for a qemu domain the following
steps are executed:
1) get list of mountpoints under /dev/
2) move them to /var/run/libvirt/qemu/$domName.ext
3) start constructing new device tree under /var/run/libvirt/qemu/$domName.dev
4) move the mountpoint of the new device tree to /dev
5) restore original mountpoints from step 2)
Not the problem with this approach is that if some device in step
3) requires access to a mountpoint from step 2) it will fail as
the mountpoint is not there anymore. For instance consider the
following domain disk configuration:
<disk type='file' device='disk'>
<driver name='qemu' type='raw'/>
<source file='/dev/shm/vhostmd0'/>
<target dev='vdb' bus='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x0a' function='0x0'/>
</disk>
In this case operation fails as we are unable to create vhostmd0
in the new device tree because after step 2) there is no /dev/shm
anymore. Leave aside fact that we shouldn't try to create devices
living in other mountpoints. That's a separate bug that will be
addressed later.
Currently, the order described above is rearranged to:
1) get list of mountpoints under /dev/
2) start constructing new device tree under /var/run/libvirt/qemu/$domName.dev
3) move them to /var/run/libvirt/qemu/$domName.ext
4) move the mountpoint of the new device tree to /dev
5) restore original mountpoints from step 3)
Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx>
---
src/qemu/qemu_domain.c | 54 +++++++++++++++++++++++++-------------------------
1 file changed, 27 insertions(+), 27 deletions(-)
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 00b0b4a..be02d54 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -7950,33 +7950,6 @@ qemuDomainBuildNamespace(virQEMUDriverConfigPtr cfg,
if (qemuDomainSetupDev(cfg, mgr, vm, devPath) < 0)
goto cleanup;
- /* Save some mount points because we want to share them with the host */
- for (i = 0; i < ndevMountsPath; i++) {
- struct stat sb;
-
- if (devMountsSavePath[i] == devPath)
- continue;
-
- if (stat(devMountsPath[i], &sb) < 0) {
- virReportSystemError(errno,
- _("Unable to stat: %s"),
- devMountsPath[i]);
- goto cleanup;
- }
-
- /* At this point, devMountsPath is either a regular file or a directory. */
- if ((S_ISDIR(sb.st_mode) && virFileMakePath(devMountsSavePath[i]) < 0) ||
- (S_ISREG(sb.st_mode) && virFileTouch(devMountsSavePath[i], sb.st_mode) < 0)) {
- virReportSystemError(errno,
- _("Failed to create %s"),
- devMountsSavePath[i]);
- goto cleanup;
- }
-
- if (virFileMoveMount(devMountsPath[i], devMountsSavePath[i]) < 0)
- goto cleanup;
- }
-
if (qemuDomainSetupAllDisks(cfg, vm, devPath) < 0)
goto cleanup;
@@ -8001,6 +7974,33 @@ qemuDomainBuildNamespace(virQEMUDriverConfigPtr cfg,
if (qemuDomainSetupAllRNGs(cfg, vm, devPath) < 0)
goto cleanup;
+ /* Save some mount points because we want to share them with the host */
+ for (i = 0; i < ndevMountsPath; i++) {
+ struct stat sb;
+
+ if (devMountsSavePath[i] == devPath)
+ continue;
+
+ if (stat(devMountsPath[i], &sb) < 0) {
+ virReportSystemError(errno,
+ _("Unable to stat: %s"),
+ devMountsPath[i]);
+ goto cleanup;
+ }
+
+ /* At this point, devMountsPath is either a regular file or a directory. */
+ if ((S_ISDIR(sb.st_mode) && virFileMakePath(devMountsSavePath[i]) < 0) ||
+ (S_ISREG(sb.st_mode) && virFileTouch(devMountsSavePath[i], sb.st_mode) < 0)) {
+ virReportSystemError(errno,
+ _("Failed to create %s"),
+ devMountsSavePath[i]);
+ goto cleanup;
+ }
+
+ if (virFileMoveMount(devMountsPath[i], devMountsSavePath[i]) < 0)
+ goto cleanup;
+ }
+
if (virFileMoveMount(devPath, "/dev") < 0)
goto cleanup;
--
2.10.2
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