On Sun, Apr 17, 2016 at 03:04:32PM -0500, serge.hallyn@xxxxxxxxxx wrote: > 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); Hm, I can't grab the cgroup mutex here because I already have the namespace_sem. But that's required by cset_cgroup_from_root(). Can I just call that under rcu_read_lock() instead? (Not without changing the lockdep_assert_help()). Is there another way to get the info needed here? > + 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 > > _______________________________________________ > Containers mailing list > Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx > https://lists.linuxfoundation.org/mailman/listinfo/containers -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html