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Commit b1664924 authored Feb 11, 2014 by Tejun Heo

cgroup: introduce cgroup_ino()



mm/memory-failure.c::hwpoison_filter_task() has been reaching into
cgroup to extract the associated ino to be used as a filtering
criterion.  This is an implementation detail which shouldn't be
depended upon from outside cgroup proper and is about to change with
the scheduled kernfs conversion.

This patch introduces a proper interface to determine the associated
ino, cgroup_ino(), and updates hwpoison_filter_task() to use it
instead of reaching directly into cgroup.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>

parent 2da440a2

include/linux/cgroup.h

+9 −0

Original line number	Diff line number	Diff line
		@@ -507,6 +507,15 @@ static inline const char cgroup_name(const struct cgroup cgrp)
		return rcu_dereference(cgrp->name)->name;
		}

		/* returns ino associated with a cgroup, 0 indicates unmounted root */
		static inline ino_t cgroup_ino(struct cgroup *cgrp)
		{
		if (cgrp->dentry)
		return cgrp->dentry->d_inode->i_ino;
		else
		return 0;
		}

		static inline struct cgroup_subsys_state seq_css(struct seq_file seq)
		{
		struct cgroup_open_file *of = seq->private;

kernel/cgroup.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -792,7 +792,10 @@ static struct inode cgroup_new_inode(umode_t mode, struct super_block sb)
		struct inode *inode = new_inode(sb);

		if (inode) {
		do {
		/* ino 0 is reserved for dummy_root */
		inode->i_ino = get_next_ino();
		} while (!inode->i_ino);
		inode->i_mode = mode;
		inode->i_uid = current_fsuid();
		inode->i_gid = current_fsgid();

mm/memory-failure.c

+2 −6

Original line number	Diff line number	Diff line
		@@ -145,14 +145,10 @@ static int hwpoison_filter_task(struct page *p)
		return -EINVAL;

		css = mem_cgroup_css(mem);
		/* root_mem_cgroup has NULL dentries */
		if (!css->cgroup->dentry)
		return -EINVAL;

		ino = css->cgroup->dentry->d_inode->i_ino;
		ino = cgroup_ino(css->cgroup);
		css_put(css);

		if (ino != hwpoison_filter_memcg)
		if (!ino \|\| ino != hwpoison_filter_memcg)
		return -EINVAL;

		return 0;