[libvirt] [PATCH 17/23] Add support for hotplug/unplug of disk devices in LXC
Daniel P. Berrange
berrange at redhat.com
Fri Nov 30 20:26:31 UTC 2012
From: "Daniel P. Berrange" <berrange at redhat.com>
Wire up the attach/detach device drivers in LXC to support the
hotplug/unplug of disks.
Signed-off-by: Daniel P. Berrange <berrange at redhat.com>
---
src/lxc/lxc_driver.c | 212 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 212 insertions(+)
diff --git a/src/lxc/lxc_driver.c b/src/lxc/lxc_driver.c
index daf32c7..a2bb497 100644
--- a/src/lxc/lxc_driver.c
+++ b/src/lxc/lxc_driver.c
@@ -30,6 +30,7 @@
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
+#include <sys/stat.h>
#include <sys/un.h>
#include <sys/poll.h>
#include <unistd.h>
@@ -2943,6 +2944,136 @@ cleanup:
static int
+lxcDomainAttachDeviceDiskLive(virLXCDriverPtr driver,
+ virDomainObjPtr vm,
+ virDomainDeviceDefPtr dev)
+{
+ virLXCDomainObjPrivatePtr priv = vm->privateData;
+ virDomainDiskDefPtr def = dev->data.disk;
+ virCgroupPtr group = NULL;
+ int ret = -1;
+ char *dst;
+ struct stat sb;
+ bool created = false;
+ mode_t mode = 0;
+ char *tmpsrc = def->src;
+
+ if (!priv->initpid) {
+ virReportError(VIR_ERR_OPERATION_INVALID, "%s",
+ _("Cannot attach disk until init PID is known"));
+ goto cleanup;
+ }
+
+ if (def->type != VIR_DOMAIN_DISK_TYPE_BLOCK) {
+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+ _("Can't setup disk for non-block device"));
+ goto cleanup;
+ }
+ if (def->src == NULL) {
+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+ _("Can't setup disk without media"));
+ goto cleanup;
+ }
+
+ if (virDomainDiskIndexByName(vm->def, def->dst, true) >= 0) {
+ virReportError(VIR_ERR_OPERATION_FAILED,
+ _("target %s already exists"), def->dst);
+ goto cleanup;
+ }
+
+ if (stat(def->src, &sb) < 0) {
+ virReportSystemError(errno,
+ _("Unable to access %s"), def->src);
+ goto cleanup;
+ }
+
+ if (!S_ISCHR(sb.st_mode) && !S_ISBLK(sb.st_mode)) {
+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+ _("Disk source %s must be a character/block device"),
+ def->src);
+ goto cleanup;
+ }
+
+ if (virAsprintf(&dst, "/proc/%llu/root/dev/%s",
+ (unsigned long long)priv->initpid, def->dst) < 0) {
+ virReportOOMError();
+ goto cleanup;
+ }
+
+ if (VIR_REALLOC_N(vm->def->disks, vm->def->ndisks+1) < 0) {
+ virReportOOMError();
+ goto cleanup;
+ }
+
+ mode = 0700;
+ if (S_ISCHR(sb.st_mode))
+ mode |= S_IFCHR;
+ else
+ mode |= S_IFBLK;
+
+ /* Yes, the device name we're creating may not
+ * actually correspond to the major:minor number
+ * we're using, but we've no other option at this
+ * time. Just have to hope that containerized apps
+ * don't get upset that the major:minor is different
+ * to that normally implied by the device name
+ */
+ VIR_DEBUG("Creating dev %s (%d,%d) from %s",
+ dst, major(sb.st_rdev), minor(sb.st_rdev), def->src);
+ if (mknod(dst, mode, sb.st_rdev) < 0) {
+ virReportSystemError(errno,
+ _("Unable to create device %s"),
+ dst);
+ goto cleanup;
+ }
+ created = true;
+
+ /* Labelling normally operates on src, but we need
+ * to actally label the dst here, so hack the config */
+ def->src = dst;
+ if (virSecurityManagerSetImageLabel(driver->securityManager,
+ vm->def, def) < 0)
+ goto cleanup;
+
+ if (!lxcCgroupControllerActive(driver, VIR_CGROUP_CONTROLLER_DEVICES)) {
+ virReportError(VIR_ERR_OPERATION_INVALID, "%s",
+ _("devices cgroup isn't mounted"));
+ goto cleanup;
+ }
+
+ if (virCgroupForDomain(driver->cgroup, vm->def->name, &group, 0) != 0) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("cannot find cgroup for domain %s"), vm->def->name);
+ goto cleanup;
+ }
+
+ if (virCgroupAllowDevicePath(group, def->src,
+ (def->readonly ?
+ VIR_CGROUP_DEVICE_READ :
+ VIR_CGROUP_DEVICE_RW) |
+ VIR_CGROUP_DEVICE_MKNOD) != 0) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("cannot allow device %s for domain %s"),
+ def->src, vm->def->name);
+ goto cleanup;
+ }
+
+ virDomainDiskInsertPreAlloced(vm->def, def);
+
+ ret = 0;
+
+cleanup:
+ def->src = tmpsrc;
+ virDomainAuditDisk(vm, NULL, def->src, "attach", ret == 0);
+ if (group)
+ virCgroupFree(&group);
+ if (dst && created && ret < 0)
+ unlink(dst);
+ return ret;
+}
+
+
+static int
lxcDomainAttachDeviceLive(virLXCDriverPtr driver ATTRIBUTE_UNUSED,
virDomainObjPtr vm ATTRIBUTE_UNUSED,
virDomainDeviceDefPtr dev)
@@ -2950,6 +3081,12 @@ lxcDomainAttachDeviceLive(virLXCDriverPtr driver ATTRIBUTE_UNUSED,
int ret = -1;
switch (dev->type) {
+ case VIR_DOMAIN_DEVICE_DISK:
+ ret = lxcDomainAttachDeviceDiskLive(driver, vm, dev);
+ if (!ret)
+ dev->data.disk = NULL;
+ break;
+
default:
virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
_("device type '%s' cannot be attached"),
@@ -2962,6 +3099,77 @@ lxcDomainAttachDeviceLive(virLXCDriverPtr driver ATTRIBUTE_UNUSED,
static int
+lxcDomainDetachDeviceDiskLive(virLXCDriverPtr driver,
+ virDomainObjPtr vm,
+ virDomainDeviceDefPtr dev)
+{
+ virLXCDomainObjPrivatePtr priv = vm->privateData;
+ virDomainDiskDefPtr def = NULL;
+ virCgroupPtr group = NULL;
+ int i, ret = -1;
+ char *dst;
+
+ if (!priv->initpid) {
+ virReportError(VIR_ERR_OPERATION_INVALID, "%s",
+ _("Cannot attach disk until init PID is known"));
+ goto cleanup;
+ }
+
+ if ((i = virDomainDiskIndexByName(vm->def,
+ dev->data.disk->dst,
+ false)) < 0) {
+ virReportError(VIR_ERR_OPERATION_FAILED,
+ _("disk %s not found"), dev->data.disk->dst);
+ goto cleanup;
+ }
+
+ def = vm->def->disks[i];
+
+ if (virAsprintf(&dst, "/proc/%llu/root/dev/%s",
+ (unsigned long long)priv->initpid, def->dst) < 0) {
+ virReportOOMError();
+ goto cleanup;
+ }
+
+ if (!lxcCgroupControllerActive(driver, VIR_CGROUP_CONTROLLER_DEVICES)) {
+ virReportError(VIR_ERR_OPERATION_INVALID, "%s",
+ _("devices cgroup isn't mounted"));
+ goto cleanup;
+ }
+
+ if (virCgroupForDomain(driver->cgroup, vm->def->name, &group, 0) != 0) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("cannot find cgroup for domain %s"), vm->def->name);
+ goto cleanup;
+ }
+
+ VIR_DEBUG("Unlinking %s (backed by %s)", dst, def->src);
+ if (unlink(dst) < 0 && errno != ENOENT) {
+ virDomainAuditDisk(vm, def->src, NULL, "detach", false);
+ virReportSystemError(errno,
+ _("Unable to remove device %s"), dst);
+ goto cleanup;
+ }
+ virDomainAuditDisk(vm, def->src, NULL, "detach", true);
+
+ if (virCgroupDenyDevicePath(group, def->src, VIR_CGROUP_DEVICE_RWM) != 0)
+ VIR_WARN("cannot deny device %s for domain %s",
+ def->src, vm->def->name);
+
+ virDomainDiskRemove(vm->def, i);
+ virDomainDiskDefFree(def);
+
+ ret = 0;
+
+cleanup:
+ VIR_FREE(dst);
+ if (group)
+ virCgroupFree(&group);
+ return ret;
+}
+
+
+static int
lxcDomainDetachDeviceLive(virLXCDriverPtr driver ATTRIBUTE_UNUSED,
virDomainObjPtr vm ATTRIBUTE_UNUSED,
virDomainDeviceDefPtr dev)
@@ -2969,6 +3177,10 @@ lxcDomainDetachDeviceLive(virLXCDriverPtr driver ATTRIBUTE_UNUSED,
int ret = -1;
switch (dev->type) {
+ case VIR_DOMAIN_DEVICE_DISK:
+ ret = lxcDomainDetachDeviceDiskLive(driver, vm, dev);
+ break;
+
default:
virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
_("device type '%s' cannot be detached"),
--
1.8.0.1
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