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synced 2024-10-05 16:37:50 +00:00
cgroup: make cgrp_dfl_root mountable
cgrp_dfl_root will be used as the default unified hierarchy. This patch makes cgrp_dfl_root mountable by making the following changes. * cgroup_init_early() now initializes cgrp_dfl_root w/ CGRP_ROOT_SANE_BEHAVIOR. The default hierarchy is always sane. * parse_cgroupfs_options() and cgroup_mount() are updated such that cgrp_dfl_root is mounted if sane_behavior is specified w/o any subsystems. * rebind_subsystems() now populates the root directory of cgrp_dfl_root. Note that the function still guarantees success of rebinding subsystems to cgrp_dfl_root. If populating fails while rebinding to cgrp_dfl_root, it whines but ignores the error. * For backward compatibility, the default hierarchy shows up in /proc/$PID/cgroup only after it's explicitly mounted so that userland which doesn't make use of it doesn't see any change. * "current_css_set_cg_links" file of debug cgroup now treats the default hierarchy the same as other hierarchies. This is visible to userland. Given that it's for debug controller, this should be fine. * While at it, implement cgroup_on_dfl() which tests whether a give cgroup is on the default hierarchy or not. The above changes make cgrp_dfl_root mostly equivalent to other controllers but the actual unified hierarchy behaviors are not implemented yet. Let's plug child cgroup creation in cgrp_dfl_root from create_cgroup() for now. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
This commit is contained in:
parent
4d3bb511b5
commit
a2dd424750
2 changed files with 71 additions and 33 deletions
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@ -250,6 +250,9 @@ enum {
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*
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*
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* - "cgroup.clone_children" is removed.
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* - "cgroup.clone_children" is removed.
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*
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*
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* - If mount is requested with sane_behavior but without any
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* subsystem, the default unified hierarchy is mounted.
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*
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* - cpuset: tasks will be kept in empty cpusets when hotplug happens
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* - cpuset: tasks will be kept in empty cpusets when hotplug happens
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* and take masks of ancestors with non-empty cpus/mems, instead of
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* and take masks of ancestors with non-empty cpus/mems, instead of
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* being moved to an ancestor.
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* being moved to an ancestor.
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@ -468,6 +471,13 @@ struct cftype {
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#endif
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#endif
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};
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};
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extern struct cgroup_root cgrp_dfl_root;
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static inline bool cgroup_on_dfl(const struct cgroup *cgrp)
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{
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return cgrp->root == &cgrp_dfl_root;
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}
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/*
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/*
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* See the comment above CGRP_ROOT_SANE_BEHAVIOR for details. This
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* See the comment above CGRP_ROOT_SANE_BEHAVIOR for details. This
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* function can be called as long as @cgrp is accessible.
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* function can be called as long as @cgrp is accessible.
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@ -142,7 +142,13 @@ static const char *cgroup_subsys_name[] = {
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* unattached - it never has more than a single cgroup, and all tasks are
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* unattached - it never has more than a single cgroup, and all tasks are
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* part of that cgroup.
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* part of that cgroup.
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*/
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*/
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static struct cgroup_root cgrp_dfl_root;
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struct cgroup_root cgrp_dfl_root;
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/*
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* The default hierarchy always exists but is hidden until mounted for the
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* first time. This is for backward compatibility.
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*/
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static bool cgrp_dfl_root_visible;
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/* The list of hierarchy roots */
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/* The list of hierarchy roots */
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@ -999,10 +1005,22 @@ static int rebind_subsystems(struct cgroup_root *dst_root,
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return -EBUSY;
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return -EBUSY;
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}
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}
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if (dst_root != &cgrp_dfl_root) {
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ret = cgroup_populate_dir(&dst_root->cgrp, ss_mask);
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ret = cgroup_populate_dir(&dst_root->cgrp, ss_mask);
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if (ret) {
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if (ret)
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if (dst_root != &cgrp_dfl_root)
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return ret;
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return ret;
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/*
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* Rebinding back to the default root is not allowed to
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* fail. Using both default and non-default roots should
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* be rare. Moving subsystems back and forth even more so.
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* Just warn about it and continue.
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*/
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if (cgrp_dfl_root_visible) {
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pr_warning("cgroup: failed to create files (%d) while rebinding 0x%lx to default root\n",
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ret, ss_mask);
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pr_warning("cgroup: you may retry by moving them to a different hierarchy and unbinding\n");
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}
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}
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}
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/*
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/*
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@ -1011,7 +1029,7 @@ static int rebind_subsystems(struct cgroup_root *dst_root,
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*/
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*/
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mutex_unlock(&cgroup_mutex);
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mutex_unlock(&cgroup_mutex);
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for_each_subsys(ss, ssid)
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for_each_subsys(ss, ssid)
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if ((ss_mask & (1 << ssid)) && ss->root != &cgrp_dfl_root)
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if (ss_mask & (1 << ssid))
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cgroup_clear_dir(&ss->root->cgrp, 1 << ssid);
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cgroup_clear_dir(&ss->root->cgrp, 1 << ssid);
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mutex_lock(&cgroup_mutex);
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mutex_lock(&cgroup_mutex);
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@ -1039,8 +1057,7 @@ static int rebind_subsystems(struct cgroup_root *dst_root,
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ss->bind(css);
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ss->bind(css);
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}
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}
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if (dst_root != &cgrp_dfl_root)
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kernfs_activate(dst_root->cgrp.kn);
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kernfs_activate(dst_root->cgrp.kn);
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return 0;
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return 0;
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}
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}
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@ -1190,16 +1207,6 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
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return -ENOENT;
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return -ENOENT;
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}
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}
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/*
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* If the 'all' option was specified select all the subsystems,
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* otherwise if 'none', 'name=' and a subsystem name options
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* were not specified, let's default to 'all'
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*/
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if (all_ss || (!one_ss && !opts->none && !opts->name))
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for_each_subsys(ss, i)
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if (!ss->disabled)
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set_bit(i, &opts->subsys_mask);
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/* Consistency checks */
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/* Consistency checks */
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if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) {
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if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) {
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@ -1211,6 +1218,23 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
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pr_err("cgroup: sane_behavior: noprefix, xattr, clone_children, release_agent and name are not allowed\n");
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pr_err("cgroup: sane_behavior: noprefix, xattr, clone_children, release_agent and name are not allowed\n");
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return -EINVAL;
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return -EINVAL;
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}
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}
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} else {
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/*
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* If the 'all' option was specified select all the
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* subsystems, otherwise if 'none', 'name=' and a subsystem
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* name options were not specified, let's default to 'all'
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*/
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if (all_ss || (!one_ss && !opts->none && !opts->name))
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for_each_subsys(ss, i)
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if (!ss->disabled)
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set_bit(i, &opts->subsys_mask);
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/*
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* We either have to specify by name or by subsystems. (So
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* all empty hierarchies must have a name).
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*/
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if (!opts->subsys_mask && !opts->name)
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return -EINVAL;
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}
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}
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/*
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/*
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@ -1226,13 +1250,6 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
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if (opts->subsys_mask && opts->none)
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if (opts->subsys_mask && opts->none)
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return -EINVAL;
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return -EINVAL;
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/*
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* We either have to specify by name or by subsystems. (So all
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* empty hierarchies must have a name).
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*/
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if (!opts->subsys_mask && !opts->name)
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return -EINVAL;
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return 0;
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return 0;
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}
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}
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@ -1487,6 +1504,14 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
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goto out_unlock;
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goto out_unlock;
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/* look for a matching existing root */
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/* look for a matching existing root */
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if (!opts.subsys_mask && !opts.none && !opts.name) {
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cgrp_dfl_root_visible = true;
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root = &cgrp_dfl_root;
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cgroup_get(&root->cgrp);
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ret = 0;
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goto out_unlock;
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}
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for_each_root(root) {
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for_each_root(root) {
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bool name_match = false;
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bool name_match = false;
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@ -3622,6 +3647,13 @@ static long cgroup_create(struct cgroup *parent, const char *name,
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struct cgroup_subsys *ss;
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struct cgroup_subsys *ss;
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struct kernfs_node *kn;
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struct kernfs_node *kn;
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/*
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* XXX: The default hierarchy isn't fully implemented yet. Block
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* !root cgroup creation on it for now.
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*/
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if (root == &cgrp_dfl_root)
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return -EINVAL;
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/* allocate the cgroup and its ID, 0 is reserved for the root */
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/* allocate the cgroup and its ID, 0 is reserved for the root */
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cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL);
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cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL);
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if (!cgrp)
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if (!cgrp)
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@ -4061,7 +4093,8 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
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*/
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*/
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int __init cgroup_init_early(void)
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int __init cgroup_init_early(void)
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{
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{
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static struct cgroup_sb_opts __initdata opts = { };
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static struct cgroup_sb_opts __initdata opts =
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{ .flags = CGRP_ROOT_SANE_BEHAVIOR };
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struct cgroup_subsys *ss;
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struct cgroup_subsys *ss;
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int i;
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int i;
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@ -4198,7 +4231,7 @@ int proc_cgroup_show(struct seq_file *m, void *v)
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struct cgroup *cgrp;
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struct cgroup *cgrp;
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int ssid, count = 0;
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int ssid, count = 0;
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if (root == &cgrp_dfl_root)
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if (root == &cgrp_dfl_root && !cgrp_dfl_root_visible)
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continue;
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continue;
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seq_printf(m, "%d:", root->hierarchy_id);
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seq_printf(m, "%d:", root->hierarchy_id);
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@ -4631,15 +4664,10 @@ static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
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cset = rcu_dereference(current->cgroups);
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cset = rcu_dereference(current->cgroups);
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list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
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list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
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struct cgroup *c = link->cgrp;
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struct cgroup *c = link->cgrp;
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const char *name = "?";
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if (c != &cgrp_dfl_root.cgrp) {
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cgroup_name(c, name_buf, NAME_MAX + 1);
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name = name_buf;
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}
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cgroup_name(c, name_buf, NAME_MAX + 1);
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seq_printf(seq, "Root %d group %s\n",
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seq_printf(seq, "Root %d group %s\n",
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c->root->hierarchy_id, name);
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c->root->hierarchy_id, name_buf);
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}
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}
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rcu_read_unlock();
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rcu_read_unlock();
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up_read(&css_set_rwsem);
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up_read(&css_set_rwsem);
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