LXC implement memory control APIs

The patch implements the missing memory control APIs for lxc, i.e.,
domainGetMaxMemory, domainSetMaxMemory, domainSetMemory, and improves
domainGetInfo to return proper amount of used memory via cgroup.

* src/libvirt_private.syms: Export virCgroupGetMemoryUsage
  and add missing virCgroupSetMemory
* src/lxc/lxc_driver.c: Implement missing memory functions
* src/util/cgroup.c, src/util/cgroup.h: Add the function
  to get used memory

src/libvirt_private.syms

@@ -53,6 +53,8 @@ virCgroupForDriver;
 virCgroupRemove;
 virCgroupFree;
 virCgroupAddTask;
+virCgroupSetMemory;
+virCgroupGetMemoryUsage;
 virCgroupSetCpuShares;
 virCgroupGetCpuShares;
 virCgroupDenyDevicePath;

src/lxc/lxc_driver.c

@@ -450,6 +450,7 @@ static int lxcDomainGetInfo(virDomainPtr dom,
 
     if (!virDomainIsActive(vm) || driver->cgroup == NULL) {
         info->cpuTime = 0;
+        info->memory = vm->def->memory;
     } else {
         if (virCgroupForDomain(driver->cgroup, vm->def->name, &cgroup, 0) != 0) {
             lxcError(dom->conn, dom, VIR_ERR_INTERNAL_ERROR,
@@ -458,13 +459,18 @@ static int lxcDomainGetInfo(virDomainPtr dom,
         }
 
         if (virCgroupGetCpuacctUsage(cgroup, &(info->cpuTime)) < 0) {
-            lxcError(dom->conn, dom, VIR_ERR_OPERATION_FAILED, ("cannot read cputime for domain"));
+            lxcError(dom->conn, dom, VIR_ERR_OPERATION_FAILED,
+                     "%s", _("cannot read cputime for domain"));
+            goto cleanup;
+        }
+        if (virCgroupGetMemoryUsage(cgroup, &(info->memory)) < 0) {
+            lxcError(dom->conn, dom, VIR_ERR_OPERATION_FAILED,
+                     "%s", _("cannot read memory usage for domain"));
             goto cleanup;
         }
     }
 
     info->maxMem = vm->def->maxmem;
-    info->memory = vm->def->memory;
     info->nrVirtCpu = 1;
     ret = 0;
 
@@ -501,6 +507,112 @@ cleanup:
     return ret;
 }
 
+/* Returns max memory in kb, 0 if error */
+static unsigned long lxcDomainGetMaxMemory(virDomainPtr dom) {
+    lxc_driver_t *driver = dom->conn->privateData;
+    virDomainObjPtr vm;
+    unsigned long ret = 0;
+
+    lxcDriverLock(driver);
+    vm = virDomainFindByUUID(&driver->domains, dom->uuid);
+    lxcDriverUnlock(driver);
+
+    if (!vm) {
+        char uuidstr[VIR_UUID_STRING_BUFLEN];
+        virUUIDFormat(dom->uuid, uuidstr);
+        lxcError(dom->conn, dom, VIR_ERR_NO_DOMAIN,
+                         _("no domain with matching uuid '%s'"), uuidstr);
+        goto cleanup;
+    }
+
+    ret = vm->def->maxmem;
+
+cleanup:
+    if (vm)
+        virDomainObjUnlock(vm);
+    return ret;
+}
+
+static int lxcDomainSetMaxMemory(virDomainPtr dom, unsigned long newmax) {
+    lxc_driver_t *driver = dom->conn->privateData;
+    virDomainObjPtr vm;
+    int ret = -1;
+
+    lxcDriverLock(driver);
+    vm = virDomainFindByUUID(&driver->domains, dom->uuid);
+    lxcDriverUnlock(driver);
+
+    if (!vm) {
+        char uuidstr[VIR_UUID_STRING_BUFLEN];
+        virUUIDFormat(dom->uuid, uuidstr);
+        lxcError(dom->conn, dom, VIR_ERR_NO_DOMAIN,
+                         _("no domain with matching uuid '%s'"), uuidstr);
+        goto cleanup;
+    }
+
+    if (newmax < vm->def->memory) {
+        lxcError(dom->conn, dom, VIR_ERR_INVALID_ARG,
+                         "%s", _("cannot set max memory lower than current memory"));
+        goto cleanup;
+    }
+
+    vm->def->maxmem = newmax;
+    ret = 0;
+
+cleanup:
+    if (vm)
+        virDomainObjUnlock(vm);
+    return ret;
+}
+
+static int lxcDomainSetMemory(virDomainPtr dom, unsigned long newmem) {
+    lxc_driver_t *driver = dom->conn->privateData;
+    virDomainObjPtr vm;
+    virCgroupPtr cgroup = NULL;
+    int ret = -1;
+
+    lxcDriverLock(driver);
+    vm = virDomainFindByUUID(&driver->domains, dom->uuid);
+    lxcDriverUnlock(driver);
+    if (!vm) {
+        char uuidstr[VIR_UUID_STRING_BUFLEN];
+        virUUIDFormat(dom->uuid, uuidstr);
+        lxcError(dom->conn, dom, VIR_ERR_NO_DOMAIN,
+                 _("no domain with matching uuid '%s'"), uuidstr);
+        goto cleanup;
+    }
+
+    if (newmem > vm->def->maxmem) {
+        lxcError(dom->conn, dom, VIR_ERR_INVALID_ARG,
+                 "%s", _("cannot set memory higher than max memory"));
+        goto cleanup;
+    }
+
+    if (virDomainIsActive(vm)) {
+        if (virCgroupForDomain(driver->cgroup, vm->def->name, &cgroup, 0) != 0) {
+            lxcError(dom->conn, dom, VIR_ERR_INTERNAL_ERROR,
+                     _("Unable to get cgroup for %s\n"), vm->def->name);
+            goto cleanup;
+        }
+
+        if (virCgroupSetMemory(cgroup, newmem) < 0) {
+            lxcError(dom->conn, dom, VIR_ERR_OPERATION_FAILED,
+                     "%s", _("cannot set memory for domain"));
+            goto cleanup;
+        }
+    } else {
+        vm->def->memory = newmem;
+    }
+    ret = 0;
+
+cleanup:
+    if (vm)
+        virDomainObjUnlock(vm);
+    if (cgroup)
+        virCgroupFree(&cgroup);
+    return ret;
+}
+
 static char *lxcDomainDumpXML(virDomainPtr dom,
                               int flags)
 {
@@ -2103,9 +2215,9 @@ static virDriver lxcDriver = {
     NULL, /* domainReboot */
     lxcDomainDestroy, /* domainDestroy */
     lxcGetOSType, /* domainGetOSType */
-    NULL, /* domainGetMaxMemory */
+    lxcDomainGetMaxMemory, /* domainGetMaxMemory */
-    NULL, /* domainSetMaxMemory */
+    lxcDomainSetMaxMemory, /* domainSetMaxMemory */
-    NULL, /* domainSetMemory */
+    lxcDomainSetMemory, /* domainSetMemory */
     lxcDomainGetInfo, /* domainGetInfo */
     NULL, /* domainSave */
     NULL, /* domainRestore */

src/util/cgroup.c

@@ -701,6 +701,26 @@ int virCgroupSetMemory(virCgroupPtr group, unsigned long kb)
                                 kb << 10);
 }
 
+/**
+ * virCgroupGetMemoryUsage:
+ *
+ * @group: The cgroup to change memory for
+ * @kb: Pointer to returned used memory in kilobytes
+ *
+ * Returns: 0 on success
+ */
+int virCgroupGetMemoryUsage(virCgroupPtr group, unsigned long *kb)
+{
+    uint64_t usage_in_bytes;
+    int ret;
+    ret = virCgroupGetValueU64(group,
+                               VIR_CGROUP_CONTROLLER_MEMORY,
+                               "memory.usage_in_bytes", &usage_in_bytes);
+    if (ret == 0)
+        *kb = (unsigned long) usage_in_bytes >> 10;
+    return ret;
+}
+
 /**
  * virCgroupDenyAllDevices:
  *

src/util/cgroup.h

@@ -41,6 +41,7 @@ int virCgroupForDomain(virCgroupPtr driver,
 int virCgroupAddTask(virCgroupPtr group, pid_t pid);
 
 int virCgroupSetMemory(virCgroupPtr group, unsigned long kb);
+int virCgroupGetMemoryUsage(virCgroupPtr group, unsigned long *kb);
 
 int virCgroupDenyAllDevices(virCgroupPtr group);