From: Serge Hallyn <serge.hallyn@xxxxxxxxxx>
When showing a cgroupfs entry in mountinfo, show the
path of the mount root dentry relative to the reader's
cgroup namespace root.
Signed-off-by: Serge Hallyn <serge.hallyn@xxxxxxxxxx>
---
fs/kernfs/mount.c | 14 ++++++++++++++
include/linux/kernfs.h | 2 ++
kernel/cgroup.c | 35 +++++++++++++++++++++++++++++++++++
3 files changed, 51 insertions(+)
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index f73541f..3b78724 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -15,6 +15,7 @@
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/namei.h>
+#include <linux/seq_file.h>
#include "kernfs-internal.h"
@@ -40,6 +41,18 @@ static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry)
return 0;
}
+static int kernfs_sop_show_path(struct seq_file *sf, struct dentry *dentry)
+{
+ struct kernfs_node *node = dentry->d_fsdata;
+ struct kernfs_root *root = kernfs_root(node);
+ struct kernfs_syscall_ops *scops = root->syscall_ops;
+
+ if (scops && scops->show_path)
+ return scops->show_path(sf, node, root);
+
+ return seq_dentry(sf, dentry, " \t\n\\");
+}
+
const struct super_operations kernfs_sops = {
.statfs = simple_statfs,
.drop_inode = generic_delete_inode,
@@ -47,6 +60,7 @@ const struct super_operations kernfs_sops = {
.remount_fs = kernfs_sop_remount_fs,
.show_options = kernfs_sop_show_options,
+ .show_path = kernfs_sop_show_path,
};
/**
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index c06c442..30f089e 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -152,6 +152,8 @@ struct kernfs_syscall_ops {
int (*rmdir)(struct kernfs_node *kn);
int (*rename)(struct kernfs_node *kn, struct kernfs_node *new_parent,
const char *new_name);
+ int (*show_path)(struct seq_file *sf, struct kernfs_node *kn,
+ struct kernfs_root *root);
};
struct kernfs_root {
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 671dc05..9a0d7b3 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1593,6 +1593,40 @@ static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
return 0;
}
+static int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
+ struct kernfs_root *kf_root)
+{
+ int len = 0, ret = 0;
+ char *buf = NULL;
+ struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;
+ struct cgroup_root *kf_cgroot = cgroup_root_from_kf(kf_root);
+ struct cgroup *ns_cgroup;
+
+ mutex_lock(&cgroup_mutex);
+ spin_lock_bh(&css_set_lock);
+ ns_cgroup = cset_cgroup_from_root(ns->root_cset, kf_cgroot);
+ len = kernfs_path_from_node(kf_node, ns_cgroup->kn, NULL, 0);
+ if (len > 0)
+ buf = kmalloc(len + 1, GFP_ATOMIC);
+ if (buf)
+ ret = kernfs_path_from_node(kf_node, ns_cgroup->kn, buf, len + 1);
+
+ spin_unlock_bh(&css_set_lock);
+ mutex_unlock(&cgroup_mutex);
+
+ if (len <= 0)
+ return len;
+ if (!buf)
+ return -ENOMEM;
+ if (ret == len) {
+ seq_escape(sf, buf, " \t\n\\");
+ ret = 0;
+ } else if (ret >= 0)
+ ret = -EINVAL;
+ kfree(buf);
+ return ret;
+}
+
static int cgroup_show_options(struct seq_file *seq,
struct kernfs_root *kf_root)
{
@@ -5430,6 +5464,7 @@ static struct kernfs_syscall_ops cgroup_kf_syscall_ops = {
.mkdir = cgroup_mkdir,
.rmdir = cgroup_rmdir,
.rename = cgroup_rename,
+ .show_path = cgroup_show_path,
};
static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early)
--
2.7.4
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