[libvirt] [PATCH V2 2/2] libxl: fix disk detach when <driver> not specified
When a user does not explicitly set a <driver> in the disk config,
libvirt defers selection of a default to libxl. This approach works
fine when starting a domain with such configuration or attaching a
disk to a running domain. But when detaching such a disk, libxl
will fail with "unrecognized disk backend type: 0". libxl makes no
attempt to recalculate a default backend (driver) on detach and
simply fails when uninitialized.
This patch updates the libvirt disk config with the backend selected
by libxl when starting a domain or attaching a disk to a running
domain. Another benefit of this approach is that the live XML is
also updated with the backend driver selected by libxl.
Signed-off-by: Jim Fehlig <jfehlig(a)suse.com>
---
src/libxl/libxl_conf.c | 32 ++++++++++++++++++++++++++++++++
src/libxl/libxl_conf.h | 4 ++++
src/libxl/libxl_domain.c | 25 +++++++++++++++++++++++++
src/libxl/libxl_driver.c | 1 +
4 files changed, 62 insertions(+)
diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
index da63105..4e38676 100644
--- a/src/libxl/libxl_conf.c
+++ b/src/libxl/libxl_conf.c
@@ -907,6 +907,38 @@ libxlMakeDiskList(virDomainDefPtr def, libxl_domain_config
*d_config)
return -1;
}
+/*
+ * Update libvirt disk config with libxl disk config.
+ *
+ * This function can be used to update the libvirt disk config with default
+ * values selected by libxl. Currently only the backend type is selected by
+ * libxl when not explicitly specified by the user.
+ */
+void
+libxlUpdateDiskDef(virDomainDiskDefPtr l_disk, libxl_device_disk *x_disk)
+{
+ const char *driver = NULL;
+
+ if (virDomainDiskGetDriver(l_disk))
+ return;
+
+ switch (x_disk->backend) {
+ case LIBXL_DISK_BACKEND_QDISK:
+ driver = "qemu";
+ break;
+ case LIBXL_DISK_BACKEND_TAP:
+ driver = "tap";
+ break;
+ case LIBXL_DISK_BACKEND_PHY:
+ driver = "phy";
+ break;
+ case LIBXL_DISK_BACKEND_UNKNOWN:
+ break;
+ }
+ if (driver)
+ ignore_value(virDomainDiskSetDriver(l_disk, driver));
+}
+
int
libxlMakeNic(virDomainDefPtr def,
virDomainNetDefPtr l_nic,
diff --git a/src/libxl/libxl_conf.h b/src/libxl/libxl_conf.h
index 69d7885..b944f6c 100644
--- a/src/libxl/libxl_conf.h
+++ b/src/libxl/libxl_conf.h
@@ -175,6 +175,10 @@ int libxlDriverConfigLoadFile(libxlDriverConfigPtr cfg,
int
libxlMakeDisk(virDomainDiskDefPtr l_dev, libxl_device_disk *x_dev);
+
+void
+libxlUpdateDiskDef(virDomainDiskDefPtr l_dev, libxl_device_disk *x_dev);
+
int
libxlMakeNic(virDomainDefPtr def,
virDomainNetDefPtr l_nic,
diff --git a/src/libxl/libxl_domain.c b/src/libxl/libxl_domain.c
index c0ace33..57ec661 100644
--- a/src/libxl/libxl_domain.c
+++ b/src/libxl/libxl_domain.c
@@ -1072,6 +1072,30 @@ libxlDomainCreateIfaceNames(virDomainDefPtr def,
libxl_domain_config *d_config)
}
}
+static void
+libxlDomainUpdateDiskParams(virDomainDefPtr def, libxl_ctx *ctx)
+{
+ libxl_device_disk *disks;
+ int num_disks = 0;
+ size_t i;
+ int idx;
+
+ disks = libxl_device_disk_list(ctx, def->id, &num_disks);
+ if (!disks)
+ return;
+
+ for (i = 0; i < num_disks; i++) {
+ if ((idx = virDomainDiskIndexByName(def, disks[i].vdev, false)) < 0)
+ continue;
+
+ libxlUpdateDiskDef(def->disks[idx], &disks[i]);
+ }
+
+ for (i = 0; i < num_disks; i++)
+ libxl_device_disk_dispose(&disks[i]);
+ VIR_FREE(disks);
+}
+
#ifdef LIBXL_HAVE_DEVICE_CHANNEL
static void
libxlDomainCreateChannelPTY(virDomainDefPtr def, libxl_ctx *ctx)
@@ -1315,6 +1339,7 @@ libxlDomainStart(libxlDriverPrivatePtr driver,
goto destroy_dom;
libxlDomainCreateIfaceNames(vm->def, &d_config);
+ libxlDomainUpdateDiskParams(vm->def, cfg->ctx);
#ifdef LIBXL_HAVE_DEVICE_CHANNEL
if (vm->def->nchannels > 0)
diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c
index 3a69720..e7827cc 100644
--- a/src/libxl/libxl_driver.c
+++ b/src/libxl/libxl_driver.c
@@ -3028,6 +3028,7 @@ libxlDomainAttachDeviceDiskLive(virDomainObjPtr vm,
virDomainDeviceDefPtr dev)
goto cleanup;
}
+ libxlUpdateDiskDef(l_disk, &x_disk);
virDomainDiskInsertPreAlloced(vm->def, l_disk);
} else {
--
2.9.2