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Track symlinks for co-mounted cgroup controllers

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If a cgroup controller is co-mounted with another, eg

   /sys/fs/cgroup/cpu,cpuacct

Then it is a requirement that there exist symlinks at

   /sys/fs/cgroup/cpu
   /sys/fs/cgroup/cpuacct

pointing to the real mount point. Add support to virCgroupPtr
to detect and track these symlinks

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
This commit is contained in:
Daniel P. Berrange 2013-04-05 11:28:04 +01:00
parent 767596bdb4
commit 83336118db
4 changed files with 143 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

56
src/util/vircgroup.c
View File

@ -75,6 +75,7 @@ void virCgroupFree(virCgroupPtr *group)
for (i = 0 ; i < VIR_CGROUP_CONTROLLER_LAST ; i++) {
VIR_FREE((*group)->controllers[i].mountPoint);
VIR_FREE((*group)->controllers[i].linkPoint);
VIR_FREE((*group)->controllers[i].placement);
}
@ -114,6 +115,14 @@ static int virCgroupCopyMounts(virCgroupPtr group,
if (!group->controllers[i].mountPoint)
return -ENOMEM;
if (parent->controllers[i].linkPoint) {
group->controllers[i].linkPoint =
strdup(parent->controllers[i].linkPoint);
if (!group->controllers[i].linkPoint)
return -ENOMEM;
}
}
return 0;
}
@ -157,9 +166,46 @@ static int virCgroupDetectMounts(virCgroupPtr group)
* first entry only
*/
if (typelen == len && STREQLEN(typestr, tmp, len) &&
!group->controllers[i].mountPoint &&
!(group->controllers[i].mountPoint = strdup(entry.mnt_dir)))
goto no_memory;
!group->controllers[i].mountPoint) {
char *linksrc;
struct stat sb;
char *tmp2;
if (!(group->controllers[i].mountPoint = strdup(entry.mnt_dir)))
goto no_memory;
tmp2 = strrchr(entry.mnt_dir, '/');
if (!tmp2) {
errno = EINVAL;
goto error;
}
*tmp2 = '\0';
/* If it is a co-mount it has a filename like "cpu,cpuacct"
* and we must identify the symlink path */
if (strchr(tmp2 + 1, ',')) {
if (virAsprintf(&linksrc, "%s/%s",
entry.mnt_dir, typestr) < 0)
goto no_memory;
*tmp2 = '/';
if (lstat(linksrc, &sb) < 0) {
if (errno == ENOENT) {
VIR_WARN("Controller %s co-mounted at %s is missing symlink at %s",
typestr, entry.mnt_dir, linksrc);
VIR_FREE(linksrc);
} else {
goto error;
}
} else {
if (!S_ISLNK(sb.st_mode)) {
VIR_WARN("Expecting a symlink at %s for controller %s",
linksrc, typestr);
} else {
group->controllers[i].linkPoint = linksrc;
}
}
}
}
tmp = next;
}
}
@ -170,8 +216,10 @@ static int virCgroupDetectMounts(virCgroupPtr group)
return 0;
no_memory:
errno = ENOMEM;
error:
VIR_FORCE_FCLOSE(mounts);
return -ENOMEM;
return -errno;
}

5
src/util/vircgrouppriv.h
View File

@ -34,6 +34,11 @@
struct virCgroupController {
int type;
char *mountPoint;
/* If mountPoint holds several controllers co-mounted,
* then linkPoint is path of the symlink to the mountPoint
* for just the one controller
*/
char *linkPoint;
char *placement;
};

58
tests/vircgroupmock.c
View File

@ -34,6 +34,8 @@
static int (*realopen)(const char *path, int flags, ...);
static FILE *(*realfopen)(const char *path, const char *mode);
static int (*realaccess)(const char *path, int mode);
static int (*reallstat)(const char *path, struct stat *sb);
static int (*real__lxstat)(int ver, const char *path, struct stat *sb);
static int (*realmkdir)(const char *path, mode_t mode);
static char *fakesysfsdir;
@ -310,8 +312,18 @@ static void init_syms(void)
} \
} while (0)
# define LOAD_SYM_ALT(name1, name2) \
do { \
if (!(real ## name1 = dlsym(RTLD_NEXT, #name1)) && \
!(real ## name2 = dlsym(RTLD_NEXT, #name2))) { \
fprintf(stderr, "Cannot find real '%s' or '%s' symbol\n", #name1, #name2); \
abort(); \
} \
} while (0)
LOAD_SYM(fopen);
LOAD_SYM(access);
LOAD_SYM_ALT(lstat, __lxstat);
LOAD_SYM(mkdir);
LOAD_SYM(open);
}
@ -395,6 +407,52 @@ int access(const char *path, int mode)
return ret;
}
int __lxstat(int ver, const char *path, struct stat *sb)
{
int ret;
init_syms();
if (STRPREFIX(path, SYSFS_PREFIX)) {
init_sysfs();
char *newpath;
if (asprintf(&newpath, "%s/%s",
fakesysfsdir,
path + strlen(SYSFS_PREFIX)) < 0) {
errno = ENOMEM;
return -1;
}
ret = real__lxstat(ver, newpath, sb);
free(newpath);
} else {
ret = real__lxstat(ver, path, sb);
}
return ret;
}
int lstat(const char *path, struct stat *sb)
{
int ret;
init_syms();
if (STRPREFIX(path, SYSFS_PREFIX)) {
init_sysfs();
char *newpath;
if (asprintf(&newpath, "%s/%s",
fakesysfsdir,
path + strlen(SYSFS_PREFIX)) < 0) {
errno = ENOMEM;
return -1;
}
ret = reallstat(newpath, sb);
free(newpath);
} else {
ret = reallstat(path, sb);
}
return ret;
}
int mkdir(const char *path, mode_t mode)
{
int ret;

36
tests/vircgrouptest.c
View File

@ -38,6 +38,7 @@
static int validateCgroup(virCgroupPtr cgroup,
const char *expectPath,
const char **expectMountPoint,
const char **expectLinkPoint,
const char **expectPlacement)
{
int i;
@ -57,6 +58,14 @@ static int validateCgroup(virCgroupPtr cgroup,
virCgroupControllerTypeToString(i));
return -1;
}
if (STRNEQ_NULLABLE(expectLinkPoint[i],
cgroup->controllers[i].linkPoint)) {
fprintf(stderr, "Wrong link '%s', expected '%s' for '%s'\n",
cgroup->controllers[i].linkPoint,
expectLinkPoint[i],
virCgroupControllerTypeToString(i));
return -1;
}
if (STRNEQ_NULLABLE(expectPlacement[i],
cgroup->controllers[i].placement)) {
fprintf(stderr, "Wrong placement '%s', expected '%s' for '%s'\n",
@ -89,6 +98,17 @@ const char *mountsFull[VIR_CGROUP_CONTROLLER_LAST] = {
[VIR_CGROUP_CONTROLLER_BLKIO] = "/not/really/sys/fs/cgroup/blkio",
};
const char *links[VIR_CGROUP_CONTROLLER_LAST] = {
[VIR_CGROUP_CONTROLLER_CPU] = "/not/really/sys/fs/cgroup/cpu",
[VIR_CGROUP_CONTROLLER_CPUACCT] = "/not/really/sys/fs/cgroup/cpuacct",
[VIR_CGROUP_CONTROLLER_CPUSET] = NULL,
[VIR_CGROUP_CONTROLLER_MEMORY] = NULL,
[VIR_CGROUP_CONTROLLER_DEVICES] = NULL,
[VIR_CGROUP_CONTROLLER_FREEZER] = NULL,
[VIR_CGROUP_CONTROLLER_BLKIO] = NULL,
};
static int testCgroupNewForSelf(const void *args ATTRIBUTE_UNUSED)
{
virCgroupPtr cgroup = NULL;
@ -108,7 +128,7 @@ static int testCgroupNewForSelf(const void *args ATTRIBUTE_UNUSED)
goto cleanup;
}
ret = validateCgroup(cgroup, "", mountsFull, placement);
ret = validateCgroup(cgroup, "", mountsFull, links, placement);
cleanup:
virCgroupFree(&cgroup);
@ -170,14 +190,14 @@ static int testCgroupNewForDriver(const void *args ATTRIBUTE_UNUSED)
fprintf(stderr, "Cannot create LXC cgroup: %d\n", -rv);
goto cleanup;
}
ret = validateCgroup(cgroup, "libvirt/lxc", mountsSmall, placementSmall);
ret = validateCgroup(cgroup, "libvirt/lxc", mountsSmall, links, placementSmall);
virCgroupFree(&cgroup);
if ((rv = virCgroupNewDriver("lxc", true, -1, &cgroup)) != 0) {
fprintf(stderr, "Cannot create LXC cgroup: %d\n", -rv);
goto cleanup;
}
ret = validateCgroup(cgroup, "libvirt/lxc", mountsFull, placementFull);
ret = validateCgroup(cgroup, "libvirt/lxc", mountsFull, links, placementFull);
cleanup:
virCgroupFree(&cgroup);
@ -211,7 +231,7 @@ static int testCgroupNewForDriverDomain(const void *args ATTRIBUTE_UNUSED)
goto cleanup;
}
ret = validateCgroup(domaincgroup, "libvirt/lxc/wibble", mountsFull, placement);
ret = validateCgroup(domaincgroup, "libvirt/lxc/wibble", mountsFull, links, placement);
cleanup:
virCgroupFree(&drivercgroup);
@ -274,14 +294,14 @@ static int testCgroupNewForPartition(const void *args ATTRIBUTE_UNUSED)
fprintf(stderr, "Cannot create /virtualmachines cgroup: %d\n", -rv);
goto cleanup;
}
ret = validateCgroup(cgroup, "/virtualmachines", mountsSmall, placementSmall);
ret = validateCgroup(cgroup, "/virtualmachines", mountsSmall, links, placementSmall);
virCgroupFree(&cgroup);
if ((rv = virCgroupNewPartition("/virtualmachines", true, -1, &cgroup)) != 0) {
fprintf(stderr, "Cannot create /virtualmachines cgroup: %d\n", -rv);
goto cleanup;
}
ret = validateCgroup(cgroup, "/virtualmachines", mountsFull, placementFull);
ret = validateCgroup(cgroup, "/virtualmachines", mountsFull, links, placementFull);
cleanup:
virCgroupFree(&cgroup);
@ -326,7 +346,7 @@ static int testCgroupNewForPartitionNested(const void *args ATTRIBUTE_UNUSED)
goto cleanup;
}
ret = validateCgroup(cgroup, "/users/berrange", mountsFull, placementFull);
ret = validateCgroup(cgroup, "/users/berrange", mountsFull, links, placementFull);
cleanup:
virCgroupFree(&cgroup);
@ -361,7 +381,7 @@ static int testCgroupNewForPartitionDomain(const void *args ATTRIBUTE_UNUSED)
goto cleanup;
}
ret = validateCgroup(domaincgroup, "/production/foo.lxc.libvirt", mountsFull, placement);
ret = validateCgroup(domaincgroup, "/production/foo.lxc.libvirt", mountsFull, links, placement);
cleanup:
virCgroupFree(&partitioncgroup);