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cgroup: introduce cgroup_ino()

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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>
This commit is contained in:
Tejun Heo 2014-02-11 11:52:49 -05:00
parent 2da440a26c
commit b166492406
3 changed files with 15 additions and 7 deletions
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9
include/linux/cgroup.h
View file

@ -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;

5
kernel/cgroup.c
View file

@ -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) {
inode->i_ino = get_next_ino();
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();

8
mm/memory-failure.c
View file

@ -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;