Commit 0a950f65 authored by Tejun Heo's avatar Tejun Heo
Browse files

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: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
Acked-by: default avatarNeil Horman <nhorman@tuxdriver.com>
parent 033fa1c5

include/linux/cgroup.h

+2 −0
Original line number Diff line number Diff line
@@ -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'.

kernel/cgroup.c

+14 −1
Original line number Diff line number Diff line
@@ -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;

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