cgroup: minor updates around cgroup_clear_directory()

* Rename it to cgroup_clear_dir() and make it take the pointer to the
  target cgroup instead of the the dentry.  This makes the function
  consistent with its counterpart - cgroup_populate_dir().

* Move cgroup_clear_directory() invocation from cgroup_d_remove_dir()
  to cgroup_remount() so that the function doesn't have to determine
  the cgroup pointer back from the dentry.  cgroup_d_remove_dir() now
  only deals with vfs, which is slightly cleaner.

This patch doesn't introduce any functional differences.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index e5583d1..09bfa87 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -957,15 +957,14 @@ static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
 }
 
 /**
- * cgroup_clear_directory - selective removal of base and subsystem files
- * @dir: directory containing the files
+ * cgroup_clear_dir - selective removal of base and subsystem files
+ * @cgrp: target cgroup
  * @base_files: true if the base files should be removed
  * @subsys_mask: mask of the subsystem ids whose files should be removed
  */
-static void cgroup_clear_directory(struct dentry *dir, bool base_files,
-                                  unsigned long subsys_mask)
+static void cgroup_clear_dir(struct cgroup *cgrp, bool base_files,
+                            unsigned long subsys_mask)
 {
-       struct cgroup *cgrp = __d_cgrp(dir);
        struct cgroup_subsys *ss;
 
        for_each_root_subsys(cgrp->root, ss) {
@@ -987,9 +986,6 @@ static void cgroup_clear_directory(struct dentry *dir, bool base_files,
 static void cgroup_d_remove_dir(struct dentry *dentry)
 {
        struct dentry *parent;
-       struct cgroupfs_root *root = dentry->d_sb->s_fs_info;
-
-       cgroup_clear_directory(dentry, true, root->subsys_mask);
 
        parent = dentry->d_parent;
        spin_lock(&parent->d_lock);
@@ -1376,7 +1372,7 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data)
         * this before rebind_subsystems, since rebind_subsystems may
         * change this hierarchy's subsys_list.
         */
-       cgroup_clear_directory(cgrp->dentry, false, removed_mask);
+       cgroup_clear_dir(cgrp, false, removed_mask);
 
        ret = rebind_subsystems(root, added_mask, removed_mask);
        if (ret) {
@@ -4541,9 +4537,10 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
        raw_spin_unlock(&release_list_lock);
 
        /*
-        * Remove @cgrp directory.  The removal puts the base ref but we
-        * aren't quite done with @cgrp yet, so hold onto it.
+        * Clear and remove @cgrp directory.  The removal puts the base ref
+        * but we aren't quite done with @cgrp yet, so hold onto it.
         */
+       cgroup_clear_dir(cgrp, true, cgrp->root->subsys_mask);
        dget(d);
        cgroup_d_remove_dir(d);