Quoting Dwight Engen (dwight.en...@oracle.com):
> This allows some special cgroup items such as memory.kmem.limit_in_bytes
> to be successfully set, since they must be set before any task is put
> into the cgroup.
>
> The devices cgroup is setup later giving the container a chance to mount
> file systems before the device it might want to mount from becomes
> unavailable.
>
> Signed-off-by: Dwight Engen <dwight.en...@oracle.com>
Acked-by: Serge E. Hallyn <serge.hal...@ubuntu.com>
thanks, Dwight.
-serge
> ---
> src/lxc/conf.c | 25 +++++++++++++++++++------
> src/lxc/conf.h | 3 +--
> src/lxc/start.c | 10 +++++++---
> 3 files changed, 27 insertions(+), 11 deletions(-)
>
> diff --git a/src/lxc/conf.c b/src/lxc/conf.c
> index 746a2db..9877cc3 100644
> --- a/src/lxc/conf.c
> +++ b/src/lxc/conf.c
> @@ -1401,7 +1401,8 @@ static int setup_kmsg(const struct lxc_rootfs *rootfs,
> return 0;
> }
>
> -int setup_cgroup(const char *cgpath, struct lxc_list *cgroups)
> +static int _setup_cgroup(const char *cgpath, struct lxc_list *cgroups,
> + int devices)
> {
> struct lxc_list *iterator;
> struct lxc_cgroup *cg;
> @@ -1411,13 +1412,15 @@ int setup_cgroup(const char *cgpath, struct lxc_list
> *cgroups)
> return 0;
>
> lxc_list_for_each(iterator, cgroups) {
> -
> cg = iterator->elem;
>
> - if (lxc_cgroup_set_bypath(cgpath, cg->subsystem, cg->value)) {
> - ERROR("Error setting %s to %s for %s\n", cg->subsystem,
> - cg->value, cgpath);
> - goto out;
> + if (devices == !strncmp("devices", cg->subsystem, 7)) {
> + if (lxc_cgroup_set_bypath(cgpath, cg->subsystem,
> + cg->value)) {
> + ERROR("Error setting %s to %s for %s\n",
> + cg->subsystem, cg->value, cgpath);
> + goto out;
> + }
> }
>
> DEBUG("cgroup '%s' set to '%s'", cg->subsystem, cg->value);
> @@ -1429,6 +1432,16 @@ out:
> return ret;
> }
>
> +int setup_cgroup_devices(const char *cgpath, struct lxc_list *cgroups)
> +{
> + return _setup_cgroup(cgpath, cgroups, 1);
> +}
> +
> +int setup_cgroup(const char *cgpath, struct lxc_list *cgroups)
> +{
> + return _setup_cgroup(cgpath, cgroups, 0);
> +}
> +
> static void parse_mntopt(char *opt, unsigned long *flags, char **data)
> {
> struct mount_opt *mo;
> diff --git a/src/lxc/conf.h b/src/lxc/conf.h
> index 465b1ec..8180e18 100644
> --- a/src/lxc/conf.h
> +++ b/src/lxc/conf.h
> @@ -287,6 +287,7 @@ struct lxc_conf {
> int run_lxc_hooks(const char *name, char *hook, struct lxc_conf *conf);
>
> extern int setup_cgroup(const char *cgpath, struct lxc_list *cgroups);
> +extern int setup_cgroup_devices(const char *cgpath, struct lxc_list
> *cgroups);
> extern int detect_shared_rootfs(void);
>
> /*
> @@ -313,8 +314,6 @@ extern int lxc_clear_cgroups(struct lxc_conf *c, const
> char *key);
> extern int lxc_clear_mount_entries(struct lxc_conf *c);
> extern int lxc_clear_hooks(struct lxc_conf *c, const char *key);
>
> -extern int setup_cgroup(const char *name, struct lxc_list *cgroups);
> -
> extern int uid_shift_ttys(int pid, struct lxc_conf *conf);
>
> /*
> diff --git a/src/lxc/start.c b/src/lxc/start.c
> index fd96d4f..cf5f9bd 100644
> --- a/src/lxc/start.c
> +++ b/src/lxc/start.c
> @@ -809,6 +809,11 @@ int lxc_spawn(struct lxc_handler *handler)
> if ((handler->cgroup = lxc_cgroup_path_create(NULL, name)) == NULL)
> goto out_delete_net;
>
> + if (setup_cgroup(handler->cgroup, &handler->conf->cgroup)) {
> + ERROR("failed to setup the cgroups for '%s'", name);
> + goto out_delete_net;
> + }
> +
> if (lxc_cgroup_enter(handler->cgroup, handler->pid) < 0)
> goto out_delete_net;
>
> @@ -839,12 +844,11 @@ int lxc_spawn(struct lxc_handler *handler)
> if (lxc_sync_barrier_child(handler, LXC_SYNC_POST_CONFIGURE))
> goto out_delete_net;
>
> - if (setup_cgroup(handler->cgroup, &handler->conf->cgroup)) {
> - ERROR("failed to setup the cgroups for '%s'", name);
> + if (setup_cgroup_devices(handler->cgroup, &handler->conf->cgroup)) {
> + ERROR("failed to setup the devices cgroup for '%s'", name);
> goto out_delete_net;
> }
>
> -
> /* Tell the child to complete its initialization and wait for
> * it to exec or return an error. (the child will never
> * return LXC_SYNC_POST_CGROUP+1. It will either close the
> --
> 1.8.1.4
>
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