From mboxrd@z Thu Jan 1 00:00:00 1970 From: serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA@public.gmane.org Subject: [PATCH 2/2] mountinfo: implement show_path for kernfs and cgroup Date: Sun, 17 Apr 2016 15:04:32 -0500 Message-ID: <1460923472-29370-3-git-send-email-serge.hallyn@ubuntu.com> References: <1460923472-29370-1-git-send-email-serge.hallyn@ubuntu.com> Return-path: In-Reply-To: <1460923472-29370-1-git-send-email-serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: adityakali-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org, gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org, Serge Hallyn List-Id: linux-api@vger.kernel.org From: Serge Hallyn 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 --- 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 #include #include +#include #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