From 0a950f65e1e64f4e82b4b5507773848ea88bcb8e Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 19 Nov 2012 09:02:12 -0800 Subject: [PATCH] cgroup: add cgroup->id With the introduction of generic cgroup hierarchy iterators, css_id is being phased out. It was unnecessarily complex, id'ing the wrong thing (cgroups need IDs, not CSSes) and has other oddities like not being available at ->css_alloc(). This patch adds cgroup->id, which is a simple per-hierarchy ida-allocated ID which is assigned before ->css_alloc() and released after ->css_free(). Signed-off-by: Tejun Heo Acked-by: Li Zefan Acked-by: Neil Horman --- include/linux/cgroup.h | 2 ++ kernel/cgroup.c | 15 ++++++++++++++- 2 files changed, 16 insertions(+), 1 deletion(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index c798997e501..82cf9e6fc77 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -159,6 +159,8 @@ struct cgroup { */ atomic_t count; + int id; /* ida allocated in-hierarchy ID */ + /* * We link our 'sibling' struct into our parent's 'children'. * Our children link their 'sibling' into our 'children'. diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 96719f73e95..6db01417d39 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -138,6 +138,9 @@ struct cgroupfs_root { /* Hierarchy-specific flags */ unsigned long flags; + /* IDs for cgroups in this hierarchy */ + struct ida cgroup_ida; + /* The path to use for release notifications. */ char release_agent_path[PATH_MAX]; @@ -890,6 +893,7 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode) simple_xattrs_free(&cgrp->xattrs); + ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id); kfree_rcu(cgrp, rcu_head); } else { struct cfent *cfe = __d_cfe(dentry); @@ -1465,6 +1469,7 @@ static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) root->subsys_mask = opts->subsys_mask; root->flags = opts->flags; + ida_init(&root->cgroup_ida); if (opts->release_agent) strcpy(root->release_agent_path, opts->release_agent); if (opts->name) @@ -1483,6 +1488,7 @@ static void cgroup_drop_root(struct cgroupfs_root *root) spin_lock(&hierarchy_id_lock); ida_remove(&hierarchy_ida, root->hierarchy_id); spin_unlock(&hierarchy_id_lock); + ida_destroy(&root->cgroup_ida); kfree(root); } @@ -4093,10 +4099,15 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, struct cgroup_subsys *ss; struct super_block *sb = root->sb; + /* allocate the cgroup and its ID, 0 is reserved for the root */ cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); if (!cgrp) return -ENOMEM; + cgrp->id = ida_simple_get(&root->cgroup_ida, 1, 0, GFP_KERNEL); + if (cgrp->id < 0) + goto err_free_cgrp; + /* * Only live parents can have children. Note that the liveliness * check isn't strictly necessary because cgroup_mkdir() and @@ -4106,7 +4117,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, */ if (!cgroup_lock_live_group(parent)) { err = -ENODEV; - goto err_free_cgrp; + goto err_free_id; } /* Grab a reference on the superblock so the hierarchy doesn't @@ -4198,6 +4209,8 @@ err_free_all: mutex_unlock(&cgroup_mutex); /* Release the reference count that we took on the superblock */ deactivate_super(sb); +err_free_id: + ida_simple_remove(&root->cgroup_ida, cgrp->id); err_free_cgrp: kfree(cgrp); return err;