cgroup: refactor mount path and clearly distinguish v1 and v2 paths
While sharing some mechanisms, the mount paths of v1 and v2 are substantially different. Their implementations were mixed in cgroup_mount(). This patch splits them out so that they're easier to follow and organize. This patch causes one functional change - the WARN_ON(new_sb) gets lost. This is because the actual mounting gets moved to cgroup_do_mount() and thus @new_sb is no longer accessible by default to cgroup1_mount(). While we can add it as an explicit out parameter to cgroup_do_mount(), this part of code hasn't changed and the warning hasn't triggered for quite a while. Dropping it should be fine. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Acked-by: Zefan Li <lizefan@huawei.com>
This commit is contained in:
Tejun Heo
Родитель
0a268dbd79
Коммит
633feee310
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@ -1989,48 +1989,55 @@ out:
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return ret;
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}
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static struct dentry *cgroup_mount(struct file_system_type *fs_type,
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int flags, const char *unused_dev_name,
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void *data)
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static struct dentry *cgroup_do_mount(struct file_system_type *fs_type,
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int flags, struct cgroup_root *root,
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unsigned long magic,
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struct cgroup_namespace *ns)
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{
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bool is_v2 = fs_type == &cgroup2_fs_type;
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struct super_block *pinned_sb = NULL;
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struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;
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struct cgroup_subsys *ss;
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struct cgroup_root *root;
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struct cgroup_sb_opts opts;
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struct dentry *dentry;
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int ret;
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int i;
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bool new_sb;
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get_cgroup_ns(ns);
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/* Check if the caller has permission to mount. */
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if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN)) {
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put_cgroup_ns(ns);
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return ERR_PTR(-EPERM);
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}
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dentry = kernfs_mount(fs_type, flags, root->kf_root, magic, &new_sb);
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/*
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* The first time anyone tries to mount a cgroup, enable the list
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* linking each css_set to its tasks and fix up all existing tasks.
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* In non-init cgroup namespace, instead of root cgroup's dentry,
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* we return the dentry corresponding to the cgroupns->root_cgrp.
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*/
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if (!use_task_css_set_links)
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cgroup_enable_task_cg_lists();
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if (!IS_ERR(dentry) && ns != &init_cgroup_ns) {
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struct dentry *nsdentry;
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struct cgroup *cgrp;
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if (is_v2) {
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if (data) {
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pr_err("cgroup2: unknown option \"%s\"\n", (char *)data);
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put_cgroup_ns(ns);
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return ERR_PTR(-EINVAL);
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}
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cgrp_dfl_visible = true;
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root = &cgrp_dfl_root;
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cgroup_get(&root->cgrp);
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goto out_mount;
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mutex_lock(&cgroup_mutex);
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spin_lock_irq(&css_set_lock);
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cgrp = cset_cgroup_from_root(ns->root_cset, root);
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spin_unlock_irq(&css_set_lock);
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mutex_unlock(&cgroup_mutex);
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nsdentry = kernfs_node_dentry(cgrp->kn, dentry->d_sb);
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dput(dentry);
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dentry = nsdentry;
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}
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if (IS_ERR(dentry) || !new_sb)
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cgroup_put(&root->cgrp);
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return dentry;
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}
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static struct dentry *cgroup1_mount(struct file_system_type *fs_type,
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int flags, void *data,
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unsigned long magic,
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struct cgroup_namespace *ns)
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{
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struct super_block *pinned_sb = NULL;
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struct cgroup_sb_opts opts;
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struct cgroup_root *root;
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struct cgroup_subsys *ss;
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struct dentry *dentry;
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int i, ret;
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cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
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/* First find the desired set of subsystems */
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@ -2152,47 +2159,58 @@ out_free:
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kfree(opts.release_agent);
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kfree(opts.name);
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if (ret) {
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put_cgroup_ns(ns);
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if (ret)
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return ERR_PTR(ret);
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}
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out_mount:
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dentry = kernfs_mount(fs_type, flags, root->kf_root,
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is_v2 ? CGROUP2_SUPER_MAGIC : CGROUP_SUPER_MAGIC,
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&new_sb);
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/*
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* In non-init cgroup namespace, instead of root cgroup's
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* dentry, we return the dentry corresponding to the
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* cgroupns->root_cgrp.
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*/
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if (!IS_ERR(dentry) && ns != &init_cgroup_ns) {
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struct dentry *nsdentry;
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struct cgroup *cgrp;
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mutex_lock(&cgroup_mutex);
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spin_lock_irq(&css_set_lock);
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cgrp = cset_cgroup_from_root(ns->root_cset, root);
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spin_unlock_irq(&css_set_lock);
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mutex_unlock(&cgroup_mutex);
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nsdentry = kernfs_node_dentry(cgrp->kn, dentry->d_sb);
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dput(dentry);
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dentry = nsdentry;
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}
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if (IS_ERR(dentry) || !new_sb)
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cgroup_put(&root->cgrp);
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dentry = cgroup_do_mount(&cgroup_fs_type, flags, root,
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CGROUP_SUPER_MAGIC, ns);
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/*
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* If @pinned_sb, we're reusing an existing root and holding an
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* extra ref on its sb. Mount is complete. Put the extra ref.
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*/
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if (pinned_sb) {
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WARN_ON(new_sb);
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if (pinned_sb)
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deactivate_super(pinned_sb);
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return dentry;
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}
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static struct dentry *cgroup_mount(struct file_system_type *fs_type,
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int flags, const char *unused_dev_name,
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void *data)
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{
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struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;
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struct dentry *dentry;
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get_cgroup_ns(ns);
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/* Check if the caller has permission to mount. */
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if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN)) {
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put_cgroup_ns(ns);
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return ERR_PTR(-EPERM);
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}
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/*
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* The first time anyone tries to mount a cgroup, enable the list
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* linking each css_set to its tasks and fix up all existing tasks.
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*/
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if (!use_task_css_set_links)
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cgroup_enable_task_cg_lists();
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if (fs_type == &cgroup2_fs_type) {
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if (data) {
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pr_err("cgroup2: unknown option \"%s\"\n", (char *)data);
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put_cgroup_ns(ns);
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return ERR_PTR(-EINVAL);
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}
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cgrp_dfl_visible = true;
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cgroup_get(&cgrp_dfl_root.cgrp);
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dentry = cgroup_do_mount(&cgroup2_fs_type, flags, &cgrp_dfl_root,
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CGROUP2_SUPER_MAGIC, ns);
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} else {
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dentry = cgroup1_mount(&cgroup_fs_type, flags, data,
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CGROUP_SUPER_MAGIC, ns);
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}
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put_cgroup_ns(ns);
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