cpusets, hotplug: Implement cpuset tree traversal in a helper function

[cascardo/linux.git] / kernel / cgroup.c

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 72fcd30..b303dfc 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -255,12 +255,17 @@ int cgroup_lock_is_held(void)
 
 EXPORT_SYMBOL_GPL(cgroup_lock_is_held);
 
+static int css_unbias_refcnt(int refcnt)
+{
+       return refcnt >= 0 ? refcnt : refcnt - CSS_DEACT_BIAS;
+}
+
 /* the current nr of refs, always >= 0 whether @css is deactivated or not */
 static int css_refcnt(struct cgroup_subsys_state *css)
 {
        int v = atomic_read(&css->refcnt);
 
-       return v >= 0 ? v : v - CSS_DEACT_BIAS;
+       return css_unbias_refcnt(v);
 }
 
 /* convenient tests for these bits */
@@ -896,13 +901,10 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode)
                mutex_unlock(&cgroup_mutex);
 
                /*
-                * We want to drop the active superblock reference from the
-                * cgroup creation after all the dentry refs are gone -
-                * kill_sb gets mighty unhappy otherwise.  Mark
-                * dentry->d_fsdata with cgroup_diput() to tell
-                * cgroup_d_release() to call deactivate_super().
+                * Drop the active superblock reference that we took when we
+                * created the cgroup
                 */
-               dentry->d_fsdata = cgroup_diput;
+               deactivate_super(cgrp->root->sb);
 
                /*
                 * if we're getting rid of the cgroup, refcount should ensure
@@ -928,13 +930,6 @@ static int cgroup_delete(const struct dentry *d)
        return 1;
 }
 
-static void cgroup_d_release(struct dentry *dentry)
-{
-       /* did cgroup_diput() tell me to deactivate super? */
-       if (dentry->d_fsdata == cgroup_diput)
-               deactivate_super(dentry->d_sb);
-}
-
 static void remove_dir(struct dentry *d)
 {
        struct dentry *parent = dget(d->d_parent);
@@ -1542,7 +1537,6 @@ static int cgroup_get_rootdir(struct super_block *sb)
        static const struct dentry_operations cgroup_dops = {
                .d_iput = cgroup_diput,
                .d_delete = cgroup_delete,
-               .d_release = cgroup_d_release,
        };
 
        struct inode *inode =
@@ -3889,8 +3883,12 @@ static void css_dput_fn(struct work_struct *work)
 {
        struct cgroup_subsys_state *css =
                container_of(work, struct cgroup_subsys_state, dput_work);
+       struct dentry *dentry = css->cgroup->dentry;
+       struct super_block *sb = dentry->d_sb;
 
-       dput(css->cgroup->dentry);
+       atomic_inc(&sb->s_active);
+       dput(dentry);
+       deactivate_super(sb);
 }
 
 static void init_cgroup_css(struct cgroup_subsys_state *css,
@@ -4982,10 +4980,12 @@ EXPORT_SYMBOL_GPL(__css_tryget);
 void __css_put(struct cgroup_subsys_state *css)
 {
        struct cgroup *cgrp = css->cgroup;
+       int v;
 
        rcu_read_lock();
-       atomic_dec(&css->refcnt);
-       switch (css_refcnt(css)) {
+       v = css_unbias_refcnt(atomic_dec_return(&css->refcnt));
+
+       switch (v) {
        case 1:
                if (notify_on_release(cgrp)) {
                        set_bit(CGRP_RELEASABLE, &cgrp->flags);