cgroup: factor out cgroup_setup_root() from cgroup_mount()
Factor out new root initialization into cgroup_setup_root() from cgroup_mount(). This makes it easier to follow and will ease kernfs conversion. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
This commit is contained in:
Tejun Heo
parent
8e30e2b8ba
commit
d427dfeb12
211
kernel/cgroup.c
211
kernel/cgroup.c
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@ -1455,17 +1455,126 @@ static int cgroup_get_rootdir(struct super_block *sb)
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return 0;
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}
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static int cgroup_setup_root(struct cgroupfs_root *root)
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{
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LIST_HEAD(tmp_links);
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struct super_block *sb = root->sb;
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struct cgroup *root_cgrp = &root->top_cgroup;
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struct cgroupfs_root *existing_root;
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struct css_set *cset;
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struct inode *inode;
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const struct cred *cred;
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int i, ret;
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lockdep_assert_held(&cgroup_tree_mutex);
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lockdep_assert_held(&cgroup_mutex);
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BUG_ON(sb->s_root != NULL);
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mutex_unlock(&cgroup_mutex);
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mutex_unlock(&cgroup_tree_mutex);
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ret = cgroup_get_rootdir(sb);
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if (ret) {
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mutex_lock(&cgroup_tree_mutex);
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mutex_lock(&cgroup_mutex);
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return ret;
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}
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inode = sb->s_root->d_inode;
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mutex_lock(&inode->i_mutex);
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mutex_lock(&cgroup_tree_mutex);
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mutex_lock(&cgroup_mutex);
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ret = idr_alloc(&root->cgroup_idr, root_cgrp, 0, 1, GFP_KERNEL);
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if (ret < 0)
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goto out_unlock;
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root_cgrp->id = ret;
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/* check for name clashes with existing mounts */
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ret = -EBUSY;
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if (strlen(root->name))
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for_each_active_root(existing_root)
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if (!strcmp(existing_root->name, root->name))
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goto out_unlock;
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/*
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* We're accessing css_set_count without locking css_set_lock here,
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* but that's OK - it can only be increased by someone holding
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* cgroup_lock, and that's us. The worst that can happen is that we
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* have some link structures left over
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*/
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ret = allocate_cgrp_cset_links(css_set_count, &tmp_links);
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if (ret)
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goto out_unlock;
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/* ID 0 is reserved for dummy root, 1 for unified hierarchy */
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ret = cgroup_init_root_id(root, 2, 0);
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if (ret)
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goto out_unlock;
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sb->s_root->d_fsdata = root_cgrp;
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root_cgrp->dentry = sb->s_root;
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/*
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* We're inside get_sb() and will call lookup_one_len() to create
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* the root files, which doesn't work if SELinux is in use. The
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* following cred dancing somehow works around it. See 2ce9738ba
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* ("cgroupfs: use init_cred when populating new cgroupfs mount")
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* for more details.
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*/
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cred = override_creds(&init_cred);
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ret = cgroup_addrm_files(root_cgrp, cgroup_base_files, true);
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if (ret)
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goto rm_base_files;
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ret = rebind_subsystems(root, root->subsys_mask, 0);
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if (ret)
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goto rm_base_files;
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revert_creds(cred);
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/*
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* There must be no failure case after here, since rebinding takes
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* care of subsystems' refcounts, which are explicitly dropped in
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* the failure exit path.
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*/
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list_add(&root->root_list, &cgroup_roots);
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cgroup_root_count++;
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/*
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* Link the top cgroup in this hierarchy into all the css_set
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* objects.
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*/
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write_lock(&css_set_lock);
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hash_for_each(css_set_table, i, cset, hlist)
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link_css_set(&tmp_links, cset, root_cgrp);
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write_unlock(&css_set_lock);
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BUG_ON(!list_empty(&root_cgrp->children));
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BUG_ON(root->number_of_cgroups != 1);
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ret = 0;
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goto out_unlock;
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rm_base_files:
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cgroup_addrm_files(&root->top_cgroup, cgroup_base_files, false);
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revert_creds(cred);
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cgroup_exit_root_id(root);
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out_unlock:
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mutex_unlock(&inode->i_mutex);
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free_cgrp_cset_links(&tmp_links);
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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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{
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LIST_HEAD(tmp_links);
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struct super_block *sb = NULL;
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struct inode *inode = NULL;
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struct cgroupfs_root *root = NULL;
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struct cgroup_sb_opts opts;
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struct cgroupfs_root *new_root;
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const struct cred *cred;
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int ret;
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mutex_lock(&cgroup_tree_mutex);
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@ -1502,94 +1611,9 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
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root = sb->s_fs_info;
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BUG_ON(!root);
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if (root == opts.new_root) {
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/* We used the new root structure, so this is a new hierarchy */
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struct cgroup *root_cgrp = &root->top_cgroup;
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struct cgroupfs_root *existing_root;
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int i;
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struct css_set *cset;
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BUG_ON(sb->s_root != NULL);
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mutex_unlock(&cgroup_mutex);
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mutex_unlock(&cgroup_tree_mutex);
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ret = cgroup_get_rootdir(sb);
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ret = cgroup_setup_root(root);
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if (ret)
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goto out_unlock;
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inode = sb->s_root->d_inode;
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mutex_lock(&inode->i_mutex);
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mutex_lock(&cgroup_tree_mutex);
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mutex_lock(&cgroup_mutex);
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ret = idr_alloc(&root->cgroup_idr, root_cgrp, 0, 1, GFP_KERNEL);
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if (ret < 0)
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goto out_unlock;
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root_cgrp->id = ret;
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/* Check for name clashes with existing mounts */
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ret = -EBUSY;
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if (strlen(root->name))
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for_each_active_root(existing_root)
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if (!strcmp(existing_root->name, root->name))
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goto out_unlock;
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/*
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* We're accessing css_set_count without locking
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* css_set_lock here, but that's OK - it can only be
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* increased by someone holding cgroup_lock, and
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* that's us. The worst that can happen is that we
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* have some link structures left over
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*/
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ret = allocate_cgrp_cset_links(css_set_count, &tmp_links);
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if (ret)
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goto out_unlock;
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/* ID 0 is reserved for dummy root, 1 for unified hierarchy */
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ret = cgroup_init_root_id(root, 2, 0);
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if (ret)
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goto out_unlock;
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sb->s_root->d_fsdata = root_cgrp;
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root_cgrp->dentry = sb->s_root;
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/*
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* We're inside get_sb() and will call lookup_one_len() to
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* create the root files, which doesn't work if SELinux is
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* in use. The following cred dancing somehow works around
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* it. See 2ce9738ba ("cgroupfs: use init_cred when
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* populating new cgroupfs mount") for more details.
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*/
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cred = override_creds(&init_cred);
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ret = cgroup_addrm_files(root_cgrp, cgroup_base_files, true);
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if (ret)
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goto rm_base_files;
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ret = rebind_subsystems(root, root->subsys_mask, 0);
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if (ret)
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goto rm_base_files;
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revert_creds(cred);
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/*
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* There must be no failure case after here, since rebinding
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* takes care of subsystems' refcounts, which are explicitly
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* dropped in the failure exit path.
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*/
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list_add(&root->root_list, &cgroup_roots);
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cgroup_root_count++;
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/* Link the top cgroup in this hierarchy into all
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* the css_set objects */
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write_lock(&css_set_lock);
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hash_for_each(css_set_table, i, cset, hlist)
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link_css_set(&tmp_links, cset, root_cgrp);
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write_unlock(&css_set_lock);
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BUG_ON(!list_empty(&root_cgrp->children));
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BUG_ON(root->number_of_cgroups != 1);
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} else {
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/*
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* We re-used an existing hierarchy - the new root (if
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@ -1609,22 +1633,13 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
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}
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ret = 0;
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goto out_unlock;
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rm_base_files:
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cgroup_addrm_files(&root->top_cgroup, cgroup_base_files, false);
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revert_creds(cred);
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cgroup_exit_root_id(root);
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out_unlock:
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mutex_unlock(&cgroup_mutex);
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mutex_unlock(&cgroup_tree_mutex);
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if (inode)
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mutex_unlock(&inode->i_mutex);
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if (ret && !IS_ERR_OR_NULL(sb))
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deactivate_locked_super(sb);
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free_cgrp_cset_links(&tmp_links);
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kfree(opts.release_agent);
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kfree(opts.name);
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