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cgroups: make it extremely obvious that we're transitioning from a fl…
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…ag to a type

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
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Christian Brauner committed Feb 17, 2021
1 parent cca7d40 commit bd09ee9
Showing 1 changed file with 27 additions and 23 deletions.
50 changes: 27 additions & 23 deletions src/lxc/cgroups/cgfsng.c
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Expand Up @@ -1770,9 +1770,9 @@ __cgfsng_ops static void cgfsng_payload_finalize(struct cgroup_ops *ops)
}

/* cgroup-full:* is done, no need to create subdirs */
static inline bool cg_mount_needs_subdirs(int cg_flags)
static inline bool cg_mount_needs_subdirs(int cgroup_automount_type)
{
switch (cg_flags) {
switch (cgroup_automount_type) {
case LXC_AUTO_CGROUP_RO:
return true;
case LXC_AUTO_CGROUP_RW:
Expand All @@ -1788,15 +1788,16 @@ static inline bool cg_mount_needs_subdirs(int cg_flags)
* remount controller ro if needed and bindmount the cgroupfs onto
* control/the/cg/path.
*/
static int cg_legacy_mount_controllers(int cg_flags, struct hierarchy *h,
static int cg_legacy_mount_controllers(int cgroup_automount_type, struct hierarchy *h,
char *controllerpath, char *cgpath,
const char *container_cgroup)
{
__do_free char *sourcepath = NULL;
int ret, remount_flags;
int flags = MS_BIND;

if ((cg_flags == LXC_AUTO_CGROUP_RO) || (cg_flags == LXC_AUTO_CGROUP_MIXED)) {
if ((cgroup_automount_type == LXC_AUTO_CGROUP_RO) ||
(cgroup_automount_type == LXC_AUTO_CGROUP_MIXED)) {
ret = mount(controllerpath, controllerpath, "cgroup", MS_BIND, NULL);
if (ret < 0)
return log_error_errno(-1, errno, "Failed to bind mount \"%s\" onto \"%s\"",
Expand All @@ -1816,7 +1817,7 @@ static int cg_legacy_mount_controllers(int cg_flags, struct hierarchy *h,

sourcepath = must_make_path(h->mountpoint, h->container_base_path,
container_cgroup, NULL);
if (cg_flags == LXC_AUTO_CGROUP_RO)
if (cgroup_automount_type == LXC_AUTO_CGROUP_RO)
flags |= MS_RDONLY;

ret = mount(sourcepath, cgpath, "cgroup", flags, NULL);
Expand Down Expand Up @@ -1844,7 +1845,7 @@ static int cg_legacy_mount_controllers(int cg_flags, struct hierarchy *h,
* uses-cases are mounting cgroup hierarchies in cgroup namespaces and mounting
* cgroups for the LXC_AUTO_CGROUP_FULL option.
*/
static int __cgroupfs_mount(int cg_flags, struct hierarchy *h,
static int __cgroupfs_mount(int cgroup_automount_type, struct hierarchy *h,
struct lxc_rootfs *rootfs, int dfd_mnt_cgroupfs,
const char *hierarchy_mnt)
{
Expand All @@ -1861,15 +1862,14 @@ static int __cgroupfs_mount(int cg_flags, struct hierarchy *h,
flags |= MOUNT_ATTR_NODEV;
flags |= MOUNT_ATTR_RELATIME;

if ((cg_flags == LXC_AUTO_CGROUP_RO) ||
(cg_flags == LXC_AUTO_CGROUP_FULL_RO))
if ((cgroup_automount_type == LXC_AUTO_CGROUP_RO) ||
(cgroup_automount_type == LXC_AUTO_CGROUP_FULL_RO))
flags |= MOUNT_ATTR_RDONLY;

if (is_unified_hierarchy(h)) {
if (is_unified_hierarchy(h))
fstype = "cgroup2";
} else {
else
fstype = "cgroup";
}

if (can_use_mount_api()) {
fd_fs = fs_prepare(fstype, -EBADF, "", 0, 0);
Expand Down Expand Up @@ -1918,19 +1918,20 @@ static int __cgroupfs_mount(int cg_flags, struct hierarchy *h,
return 0;
}

static inline int cgroupfs_mount(int cg_flags, struct hierarchy *h,
static inline int cgroupfs_mount(int cgroup_automount_type, struct hierarchy *h,
struct lxc_rootfs *rootfs,
int dfd_mnt_cgroupfs, const char *hierarchy_mnt)
{
return __cgroupfs_mount(cg_flags, h, rootfs, dfd_mnt_cgroupfs, hierarchy_mnt);
return __cgroupfs_mount(cgroup_automount_type, h, rootfs,
dfd_mnt_cgroupfs, hierarchy_mnt);
}

static inline int cgroupfs_bind_mount(int cg_flags, struct hierarchy *h,
static inline int cgroupfs_bind_mount(int cgroup_automount_type, struct hierarchy *h,
struct lxc_rootfs *rootfs,
int dfd_mnt_cgroupfs,
const char *hierarchy_mnt)
{
switch (cg_flags) {
switch (cgroup_automount_type) {
case LXC_AUTO_CGROUP_FULL_RO:
break;
case LXC_AUTO_CGROUP_FULL_RW:
Expand All @@ -1941,14 +1942,16 @@ static inline int cgroupfs_bind_mount(int cg_flags, struct hierarchy *h,
return 0;
}

return __cgroupfs_mount(cg_flags, h, rootfs, dfd_mnt_cgroupfs, hierarchy_mnt);
return __cgroupfs_mount(cgroup_automount_type, h, rootfs,
dfd_mnt_cgroupfs, hierarchy_mnt);
}

__cgfsng_ops static bool cgfsng_mount(struct cgroup_ops *ops,
struct lxc_handler *handler, int cg_flags)
{
__do_close int dfd_mnt_tmpfs = -EBADF, fd_fs = -EBADF;
__do_free char *cgroup_root = NULL;
int cgroup_automount_type;
bool in_cgroup_ns = false, wants_force_mount = false;
struct lxc_conf *conf = handler->conf;
struct lxc_rootfs *rootfs = &conf->rootfs;
Expand Down Expand Up @@ -1994,6 +1997,7 @@ __cgfsng_ops static bool cgfsng_mount(struct cgroup_ops *ops,
default:
return log_error_errno(false, EINVAL, "Invalid cgroup mount options specified");
}
cgroup_automount_type = cg_flags;

if (!wants_force_mount) {
wants_force_mount = !lxc_wants_cap(CAP_SYS_ADMIN, conf);
Expand Down Expand Up @@ -2021,8 +2025,8 @@ __cgfsng_ops static bool cgfsng_mount(struct cgroup_ops *ops,
* since the parent directory of the container's cgroup is not
* accessible to the container.
*/
cg_flags &= ~LXC_AUTO_CGROUP_MIXED;
cg_flags &= ~LXC_AUTO_CGROUP_FULL_MIXED;
cgroup_automount_type &= ~LXC_AUTO_CGROUP_MIXED;
cgroup_automount_type &= ~LXC_AUTO_CGROUP_FULL_MIXED;
}

if (in_cgroup_ns && !wants_force_mount)
Expand Down Expand Up @@ -2067,7 +2071,7 @@ __cgfsng_ops static bool cgfsng_mount(struct cgroup_ops *ops,
* 11. cgroup-full:ro:force -> Not supported.
* 12. cgroup-full:mixed:force -> Not supported.
*/
ret = cgroupfs_mount(cg_flags, ops->unified, rootfs, dfd_mnt_unified, "");
ret = cgroupfs_mount(cgroup_automount_type, ops->unified, rootfs, dfd_mnt_unified, "");
if (ret < 0)
return syserrno(false, "Failed to force mount cgroup filesystem in cgroup namespace");

Expand Down Expand Up @@ -2160,19 +2164,19 @@ __cgfsng_ops static bool cgfsng_mount(struct cgroup_ops *ops,
* will not have CAP_SYS_ADMIN after it has started we
* need to mount the cgroups manually.
*/
ret = cgroupfs_mount(cg_flags, h, rootfs, dfd_mnt_tmpfs, controller);
ret = cgroupfs_mount(cgroup_automount_type, h, rootfs, dfd_mnt_tmpfs, controller);
if (ret < 0)
return false;

continue;
}

/* Here is where the ancient kernel section begins. */
ret = cgroupfs_bind_mount(cg_flags, h, rootfs, dfd_mnt_tmpfs, controller);
ret = cgroupfs_bind_mount(cgroup_automount_type, h, rootfs, dfd_mnt_tmpfs, controller);
if (ret < 0)
return false;

if (!cg_mount_needs_subdirs(cg_flags))
if (!cg_mount_needs_subdirs(cgroup_automount_type))
continue;

if (!cgroup_root)
Expand All @@ -2184,7 +2188,7 @@ __cgfsng_ops static bool cgfsng_mount(struct cgroup_ops *ops,
if (ret < 0 && (errno != EEXIST))
return false;

ret = cg_legacy_mount_controllers(cg_flags, h, controllerpath, path2, ops->container_cgroup);
ret = cg_legacy_mount_controllers(cgroup_automount_type, h, controllerpath, path2, ops->container_cgroup);
if (ret < 0)
return false;
}
Expand Down

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