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| author | Tejun Heo <tj@kernel.org> | 2014-02-11 11:52:49 -0500 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2014-02-11 11:52:49 -0500 |
| commit | b1664924062393bb048203bd4622e0b1c9e1d328 (patch) | |
| tree | 4fbbb4a62793e72d9dbe44c71db0ea75f54cc21b | |
| parent | 2da440a26ce4743bd3e71ba964ba3f983d09bba5 (diff) | |
| download | lwn-b1664924062393bb048203bd4622e0b1c9e1d328.tar.gz lwn-b1664924062393bb048203bd4622e0b1c9e1d328.zip | |
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>
| -rw-r--r-- | include/linux/cgroup.h | 9 | ||||
| -rw-r--r-- | kernel/cgroup.c | 5 | ||||
| -rw-r--r-- | mm/memory-failure.c | 8 |
3 files changed, 15 insertions, 7 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 63feaed83bc6..06f577764414 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -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; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 42e588ef62d1..11f7a05e791e 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -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(); diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 4f08a2d61487..9b5933c66c16 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -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; |