Add forgotten cgroup.{c,h} and ChangeLog

ChangeLog

+Thu Oct  3 09:32:42 PDT 2008 Dan Smith <danms@us.ibm.com>
+	* src/lxc_container.h src/lxc_container.c
+	  src/lxc_controller.c src/lxc_driver.c: Use internal cgroup
+	  API to manipulate cgroups for LXC resource control
+
+Thu Oct  3 09:32:42 PDT 2008 Dan Smith <danms@us.ibm.com>
+	* src/cgroup.c src/cgroup.h: Add internal cgroup manipulation API
+
 Thu Oct  2 17:01:32 CEST 2008 Daniel Veillard <veillard@redhat.com>
 
 	* libvirt.spec.in: fix bug #465274 to build on RHEL

src/cgroup.c

+/*
+ * cgroup.c: Tools for managing cgroups
+ *
+ * Copyright IBM Corp. 2008
+ *
+ * See COPYING.LIB for the License of this software
+ *
+ * Authors:
+ *  Dan Smith <danms@us.ibm.com>
+ */
+#include <config.h>
+
+#include <stdio.h>
+#include <stdint.h>
+#include <inttypes.h>
+#include <mntent.h>
+#include <fcntl.h>
+#include <string.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <libgen.h>
+
+#include "internal.h"
+#include "util.h"
+#include "memory.h"
+#include "cgroup.h"
+
+#define DEBUG(fmt,...) VIR_DEBUG(__FILE__, fmt, __VA_ARGS__)
+#define DEBUG0(msg) VIR_DEBUG(__FILE__, "%s", msg)
+
+#define CGROUP_MAX_VAL 512
+
+struct virCgroup {
+    char *path;
+};
+
+const char *supported_controllers[] = {
+    "memory",
+    "devices",
+    NULL
+};
+
+/**
+ * virCgroupFree:
+ *
+ * @group: The group structure to free
+ */
+void virCgroupFree(virCgroupPtr *group)
+{
+    if (*group != NULL) {
+        VIR_FREE((*group)->path);
+        VIR_FREE(*group);
+        *group = NULL;
+    }
+}
+
+static virCgroupPtr virCgroupGetMount(const char *controller)
+{
+    FILE *mounts;
+    struct mntent entry;
+    char buf[CGROUP_MAX_VAL];
+    virCgroupPtr root = NULL;
+
+    if (VIR_ALLOC(root) != 0)
+        return NULL;
+
+    mounts = fopen("/proc/mounts", "r");
+    if (mounts == NULL) {
+        DEBUG0("Unable to open /proc/mounts: %m");
+        goto err;
+    }
+
+    while (getmntent_r(mounts, &entry, buf, sizeof(buf)) != NULL) {
+        if (STREQ(entry.mnt_type, "cgroup") &&
+            (strstr(entry.mnt_opts, controller))) {
+            root->path = strdup(entry.mnt_dir);
+            break;
+        }
+    }
+
+    DEBUG("Mount for %s is %s\n", controller, root->path);
+
+    if (root->path == NULL) {
+        DEBUG0("Did not find cgroup mount");
+        goto err;
+    }
+
+    fclose(mounts);
+
+    return root;
+err:
+    virCgroupFree(&root);
+
+    return NULL;
+}
+
+/**
+ * virCgroupHaveSupport:
+ *
+ * Returns 0 if support is present, negative if not
+ */
+int virCgroupHaveSupport(void)
+{
+    virCgroupPtr root;
+    int i;
+
+    for (i = 0; supported_controllers[i] != NULL; i++) {
+        root = virCgroupGetMount(supported_controllers[i]);
+        if (root == NULL)
+            return -1;
+        virCgroupFree(&root);
+    }
+
+    return 0;
+}
+
+static int virCgroupPathOfGroup(const char *group,
+                                const char *controller,
+                                char **path)
+{
+    virCgroupPtr root = NULL;
+    int rc = 0;
+
+    root = virCgroupGetMount(controller);
+    if (root == NULL) {
+        rc = -ENOTDIR;
+        goto out;
+    }
+
+    if (asprintf(path, "%s/%s", root->path, group) == -1)
+        rc = -ENOMEM;
+out:
+    virCgroupFree(&root);
+
+    return rc;
+}
+
+static int virCgroupPathOf(const char *grppath,
+                           const char *key,
+                           char **path)
+{
+    virCgroupPtr root;
+    int rc = 0;
+    char *controller = NULL;
+
+    if (strchr(key, '.') == NULL)
+        return -EINVAL;
+
+    if (sscanf(key, "%a[^.]", &controller) != 1)
+        return -EINVAL;
+
+    root = virCgroupGetMount(controller);
+    if (root == NULL) {
+        rc = -ENOTDIR;
+        goto out;
+    }
+
+    if (asprintf(path, "%s/%s/%s", root->path, grppath, key) == -1)
+        rc = -ENOMEM;
+out:
+    virCgroupFree(&root);
+    VIR_FREE(controller);
+
+    return rc;
+}
+
+static int virCgroupSetValueStr(virCgroupPtr group,
+                                const char *key,
+                                const char *value)
+{
+    int fd = -1;
+    int rc = 0;
+    char *keypath = NULL;
+
+    rc = virCgroupPathOf(group->path, key, &keypath);
+    if (rc != 0)
+        return rc;
+
+    fd = open(keypath, O_WRONLY);
+    if (fd < 0) {
+        DEBUG("Unable to open %s: %m", keypath);
+        rc = -ENOENT;
+        goto out;
+    }
+
+    DEBUG("Writing '%s' to '%s'", value, keypath);
+
+    rc = safewrite(fd, value, strlen(value));
+    if (rc < 0) {
+        DEBUG("Failed to write value '%s': %m", value);
+        rc = -errno;
+        goto out;
+    } else if (rc != strlen(value)) {
+        DEBUG("Short write of value '%s'", value);
+        rc = -ENOSPC;
+        goto out;
+    }
+
+    rc = 0;
+out:
+    VIR_FREE(keypath);
+    close(fd);
+
+    return rc;
+}
+
+static int virCgroupSetValueU64(virCgroupPtr group,
+                                const char *key,
+                                uint64_t value)
+{
+    char *strval = NULL;
+    int rc;
+
+    if (asprintf(&strval, "%" PRIu64, value) == -1)
+        return -ENOMEM;
+
+    rc = virCgroupSetValueStr(group, key, strval);
+
+    VIR_FREE(strval);
+
+    return rc;
+}
+
+#if 0
+/* This is included for completeness, but not yet used */
+
+static int virCgroupSetValueI64(virCgroupPtr group,
+                                const char *key,
+                                int64_t value)
+{
+    char *strval = NULL;
+    int rc;
+
+    if (asprintf(&strval, "%" PRIi64, value) == -1)
+        return -ENOMEM;
+
+    rc = virCgroupSetValueStr(group, key, strval);
+
+    VIR_FREE(strval);
+
+    return rc;
+}
+
+static int virCgroupGetValueStr(virCgroupPtr group,
+                                const char *key,
+                                char **value)
+{
+    int fd = -1;
+    int rc;
+    char *keypath = NULL;
+    char buf[CGROUP_MAX_VAL];
+
+    memset(buf, 0, sizeof(buf));
+
+    rc = virCgroupPathOf(group->path, key, &keypath);
+    if (rc != 0) {
+        DEBUG("No path of %s, %s", group->path, key);
+        return rc;
+    }
+
+    fd = open(keypath, O_RDONLY);
+    if (fd < 0) {
+        DEBUG("Unable to open %s: %m", keypath);
+        rc = -ENOENT;
+        goto out;
+    }
+
+    rc = saferead(fd, buf, sizeof(buf));
+    if (rc < 0) {
+        DEBUG("Failed to read %s: %m\n", keypath);
+        rc = -errno;
+        goto out;
+    } else if (rc == 0) {
+        DEBUG("Short read of %s\n", keypath);
+        rc = -EIO;
+        goto out;
+    }
+
+    *value = strdup(buf);
+    if (*value == NULL) {
+        rc = -ENOMEM;
+        goto out;
+    }
+
+    rc = 0;
+out:
+    VIR_FREE(keypath);
+    close(fd);
+
+    return rc;
+}
+
+static int virCgroupGetValueU64(virCgroupPtr group,
+                                const char *key,
+                                uint64_t *value)
+{
+    char *strval = NULL;
+    int rc = 0;
+
+    rc = virCgroupGetValueStr(group, key, &strval);
+    if (rc != 0)
+        goto out;
+
+    if (sscanf(strval, "%" SCNu64, value) != 1)
+        rc = -EINVAL;
+out:
+    VIR_FREE(strval);
+
+    return rc;
+}
+
+static int virCgroupGetValueI64(virCgroupPtr group,
+                                const char *key,
+                                int64_t *value)
+{
+    char *strval = NULL;
+    int rc = 0;
+
+    rc = virCgroupGetValueStr(group, key, &strval);
+    if (rc != 0)
+        goto out;
+
+    if (sscanf(strval, "%" SCNi64, value) != 1)
+        rc = -EINVAL;
+out:
+    VIR_FREE(strval);
+
+    return rc;
+}
+#endif
+
+static int _virCgroupInherit(const char *path,
+                             const char *key)
+{
+    int rc = 0;
+    int fd = -1;
+    char buf[CGROUP_MAX_VAL];
+    char *keypath = NULL;
+    char *pkeypath = NULL;
+
+    memset(buf, 0, sizeof(buf));
+
+    if (asprintf(&keypath, "%s/%s", path, key) == -1) {
+        rc = -ENOMEM;
+        goto out;
+    }
+
+    if (access(keypath, F_OK) != 0) {
+        DEBUG("Group %s has no key %s\n", path, key);
+        goto out;
+    }
+
+    if (asprintf(&pkeypath, "%s/../%s", path, key) == -1) {
+        rc = -ENOMEM;
+        VIR_FREE(keypath);
+        goto out;
+    }
+
+    fd = open(pkeypath, O_RDONLY);
+    if (fd < 0) {
+        rc = -errno;
+        goto out;
+    }
+
+    if (saferead(fd, buf, sizeof(buf)) <= 0) {
+        rc = -errno;
+        goto out;
+    }
+
+    close(fd);
+
+    fd = open(keypath, O_WRONLY);
+    if (fd < 0) {
+        rc = -errno;
+        goto out;
+    }
+
+    if (safewrite(fd, buf, strlen(buf)) != strlen(buf)) {
+        rc = -errno;
+        goto out;
+    }
+
+out:
+    VIR_FREE(keypath);
+    VIR_FREE(pkeypath);
+    close(fd);
+
+    return rc;
+}
+
+static int virCgroupInherit(const char *grppath)
+{
+    int i;
+    int rc = 0;
+    const char *inherit_values[] = {
+        "cpuset.cpus",
+        "cpuset.mems",
+        NULL
+    };
+
+    for (i = 0; inherit_values[i] != NULL; i++) {
+        const char *key = inherit_values[i];
+
+        rc = _virCgroupInherit(grppath, key);
+        if (rc != 0) {
+            DEBUG("inherit of %s failed\n", key);
+            break;
+        }
+    }
+
+    return rc;
+}
+
+static int virCgroupMakeGroup(const char *name)
+{
+    int i;
+    int rc = 0;
+
+    for (i = 0; supported_controllers[i] != NULL; i++) {
+        char *path = NULL;
+        virCgroupPtr root;
+
+        root = virCgroupGetMount(supported_controllers[i]);
+        if (root == NULL)
+            continue;
+
+        rc = virCgroupPathOfGroup(name, supported_controllers[i], &path);
+        if (rc != 0) {
+            virCgroupFree(&root);
+            break;
+        }
+
+        virCgroupFree(&root);
+
+        if (access(path, F_OK) != 0) {
+            if (mkdir(path, 0655) < 0) {
+                rc = -errno;
+                VIR_FREE(path);
+                break;
+            }
+            virCgroupInherit(path);
+        }
+
+        VIR_FREE(path);
+    }
+
+    return rc;
+}
+
+static int virCgroupRoot(virCgroupPtr *root)
+{
+    int rc = 0;
+    char *grppath = NULL;
+
+    if (VIR_ALLOC((*root)) != 0) {
+        rc = -ENOMEM;
+        goto out;
+    }
+
+    (*root)->path = strdup("libvirt");
+    if ((*root)->path == NULL) {
+        rc = -ENOMEM;
+        goto out;
+    }
+
+    rc = virCgroupMakeGroup((*root)->path);
+out:
+    if (rc != 0)
+        virCgroupFree(root);
+    VIR_FREE(grppath);
+
+    return rc;
+}
+
+static int virCgroupNew(virCgroupPtr *parent,
+                        const char *group,
+                        virCgroupPtr *newgroup)
+{
+    int rc = 0;
+    char *typpath = NULL;
+
+    *newgroup = NULL;
+
+    if (*parent == NULL) {
+        rc = virCgroupRoot(parent);
+        if (rc != 0)
+            goto err;
+    }
+
+    if (VIR_ALLOC((*newgroup)) != 0) {
+        rc = -ENOMEM;
+        goto err;
+    }
+
+    rc = asprintf(&((*newgroup)->path),
+                  "%s/%s",
+                  (*parent)->path,
+                  group);
+    if (rc == -1) {
+        rc = -ENOMEM;
+        goto err;
+    }
+
+    rc = 0;
+
+    return rc;
+err:
+    virCgroupFree(newgroup);
+    *newgroup = NULL;
+
+    VIR_FREE(typpath);
+
+    return rc;
+}
+
+static int virCgroupOpen(virCgroupPtr parent,
+                         const char *group,
+                         virCgroupPtr *newgroup)
+{
+    int rc = 0;
+    char *grppath = NULL;
+    bool free_parent = (parent == NULL);
+
+    rc = virCgroupNew(&parent, group, newgroup);
+    if (rc != 0)
+        goto err;
+
+    if (free_parent)
+        virCgroupFree(&parent);
+
+    rc = virCgroupPathOfGroup((*newgroup)->path,
+                              supported_controllers[0],
+                              &grppath);
+    if (rc != 0)
+        goto err;
+
+    if (access(grppath, F_OK) != 0) {
+        rc = -ENOENT;
+        goto err;
+    }
+
+    return rc;
+err:
+    virCgroupFree(newgroup);
+    *newgroup = NULL;
+
+    return rc;
+}
+
+static int virCgroupCreate(virCgroupPtr parent,
+                           const char *group,
+                           virCgroupPtr *newgroup)
+{
+    int rc = 0;
+    bool free_parent = (parent == NULL);
+
+    rc = virCgroupNew(&parent, group, newgroup);
+    if (rc != 0) {
+        DEBUG0("Unable to allocate new virCgroup structure");
+        goto err;
+    }
+
+    rc = virCgroupMakeGroup((*newgroup)->path);
+    if (rc != 0)
+        goto err;
+
+    if (free_parent)
+        virCgroupFree(&parent);
+
+    return rc;
+err:
+    virCgroupFree(newgroup);
+    *newgroup = NULL;
+
+    if (free_parent)
+        virCgroupFree(&parent);
+
+    return rc;
+}
+
+/**
+ * virCgroupRemove:
+ *
+ * @group: The group to be removed
+ *
+ * Returns: 0 on success
+ */
+int virCgroupRemove(virCgroupPtr group)
+{
+    int rc = 0;
+    int i;
+    char *grppath = NULL;
+
+    for (i = 0; supported_controllers[i] != NULL; i++) {
+        if (virCgroupPathOfGroup(group->path,
+                                 supported_controllers[i],
+                                 &grppath) != 0)
+            continue;
+
+        if (rmdir(grppath) != 0)
+            rc = -errno;
+
+        VIR_FREE(grppath);
+    }
+
+    return rc;
+}
+
+/**
+ * virCgroupAddTask:
+ *
+ * @group: The cgroup to add a task to
+ * @pid: The pid of the task to add
+ *
+ * Returns: 0 on success
+ */
+int virCgroupAddTask(virCgroupPtr group, pid_t pid)
+{
+    int rc = 0;
+    int fd = -1;
+    int i;
+    char *grppath = NULL;
+    char *taskpath = NULL;
+    char *pidstr = NULL;
+
+    for (i = 0; supported_controllers[i] != NULL; i++) {
+        rc = virCgroupPathOfGroup(group->path,
+                                  supported_controllers[i],
+                                  &grppath);
+        if (rc != 0)
+            goto done;
+
+        if (asprintf(&taskpath, "%s/tasks", grppath) == -1) {
+            rc = -ENOMEM;
+            goto done;
+        }
+
+        fd = open(taskpath, O_WRONLY);
+        if (fd < 0) {
+            rc = -errno;
+            goto done;
+        }
+
+        if (asprintf(&pidstr, "%lu", (unsigned long)pid) == -1) {
+            rc = -ENOMEM;
+            goto done;
+        }
+
+        if (write(fd, pidstr, strlen(pidstr)) <= 0) {
+            rc = -errno;
+            goto done;
+        }
+
+    done:
+        VIR_FREE(grppath);
+        VIR_FREE(taskpath);
+        VIR_FREE(pidstr);
+        close(fd);
+
+        if (rc != 0)
+            break;
+    }
+
+    return rc;
+}
+
+/**
+ * virCgroupForDomain:
+ *
+ * @def: Domain definition to create cgroup for
+ * @driverName: Classification of this domain type (e.g., xen, qemu, lxc)
+ * @group: Pointer to returned virCgroupPtr
+ *
+ * Returns 0 on success
+ */
+int virCgroupForDomain(virDomainDefPtr def,
+                       const char *driverName,
+                       virCgroupPtr *group)
+{
+    int rc;
+    virCgroupPtr typegrp = NULL;
+
+    rc = virCgroupOpen(NULL, driverName, &typegrp);
+    if (rc == -ENOENT) {
+        rc = virCgroupCreate(NULL, driverName, &typegrp);
+        if (rc != 0)
+            goto out;
+    } else if (rc != 0)
+        goto out;
+
+    rc = virCgroupOpen(typegrp, def->name, group);
+    if (rc == -ENOENT)
+        rc = virCgroupCreate(typegrp, def->name, group);
+out:
+    virCgroupFree(&typegrp);
+
+    return rc;
+}
+
+/**
+ * virCgroupSetMemory:
+ *
+ * @group: The cgroup to change memory for
+ * @kb: The memory amount in kilobytes
+ *
+ * Returns: 0 on success
+ */
+int virCgroupSetMemory(virCgroupPtr group, unsigned long kb)
+{
+    return virCgroupSetValueU64(group,
+                                "memory.limit_in_bytes",
+                                kb << 10);
+}
+
+/**
+ * virCgroupDenyAllDevices:
+ *
+ * @group: The cgroup to deny devices for
+ *
+ * Returns: 0 on success
+ */
+int virCgroupDenyAllDevices(virCgroupPtr group)
+{
+    return virCgroupSetValueStr(group,
+                              "devices.deny",
+                              "a");
+}
+
+/**
+ * virCgroupAllowDevice:
+ *
+ * @group: The cgroup to allow a device for
+ * @type: The device type (i.e., 'c' or 'b')
+ * @major: The major number of the device
+ * @minor: The minor number of the device
+ *
+ * Returns: 0 on success
+ */
+int virCgroupAllowDevice(virCgroupPtr group,
+                         char type,
+                         int major,
+                         int minor)
+{
+    int rc;
+    char *devstr = NULL;
+
+    if (asprintf(&devstr, "%c %i:%i rwm", type, major, minor) == -1) {
+        rc = -ENOMEM;
+        goto out;
+    }
+
+    rc = virCgroupSetValueStr(group,
+                              "devices.allow",
+                              devstr);
+out:
+    VIR_FREE(devstr);
+
+    return rc;
+}

src/cgroup.h

+/*
+ * cgroup.h: Interface to tools for managing cgroups
+ *
+ * Copyright IBM Corp. 2008
+ *
+ * See COPYING.LIB for the License of this software
+ *
+ * Authors:
+ *  Dan Smith <danms@us.ibm.com>
+ */
+
+#ifndef CGROUP_H
+#define CGROUP_H
+
+#include <stdint.h>
+
+struct virCgroup;
+typedef struct virCgroup *virCgroupPtr;
+
+#include "domain_conf.h"
+
+int virCgroupHaveSupport(void);
+
+int virCgroupForDomain(virDomainDefPtr def,
+                       const char *driverName,
+                       virCgroupPtr *group);
+
+int virCgroupAddTask(virCgroupPtr group, pid_t pid);
+
+int virCgroupSetMemory(virCgroupPtr group, unsigned long kb);
+
+int virCgroupDenyAllDevices(virCgroupPtr group);
+
+int virCgroupAllowDevice(virCgroupPtr group,
+                         char type,
+                         int major,
+                         int minor);
+
+int virCgroupRemove(virCgroupPtr group);
+
+void virCgroupFree(virCgroupPtr *group);
+
+#endif /* CGROUP_H */