[Devel] [PATCH rh7 1/6] cgroup: add function to lookup a cgroup by pathname

[Vladimir Davydov]

Will be used later.

Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>
---
 fs/internal.h          |  2 --
 include/linux/cgroup.h |  2 ++
 include/linux/fs.h     |  2 ++
 kernel/cgroup.c        | 23 +++++++++++++++++++++++
 4 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/fs/internal.h b/fs/internal.h
index a592cd36971e..fc66b23c65db 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -47,8 +47,6 @@ extern void __init chrdev_init(void);
  */
 extern int __inode_permission(struct inode *, int);
 extern int user_path_mountpoint_at(int, const char __user *, unsigned int, struct path *);
-extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
-			   const char *, unsigned int, struct path *);
 
 /*
  * namespace.c
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 0108a98bb911..52fe02af71b5 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -50,6 +50,8 @@ enum cgroup_open_flags {
 
 struct vfsmount *cgroup_kernel_mount(struct cgroup_sb_opts *opts);
 struct cgroup *cgroup_get_root(struct vfsmount *mnt);
+struct cgroup *cgroup_kernel_lookup(struct vfsmount *mnt,
+				    const char *pathname);
 struct cgroup *cgroup_kernel_open(struct cgroup *parent,
 		enum cgroup_open_flags flags, const char *name);
 int cgroup_kernel_remove(struct cgroup *parent, const char *name);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9efd253c6da1..bc494a0d4616 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1596,6 +1596,8 @@ extern int vfs_link(struct dentry *, struct inode *, struct dentry *, struct ino
 extern int vfs_rmdir(struct inode *, struct dentry *);
 extern int vfs_unlink(struct inode *, struct dentry *, struct inode **);
 extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *, struct inode **);
+extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
+			   const char *, unsigned int, struct path *);
 
 /*
  * VFS dentry helper functions.
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 9b3d0e2ebbae..cca5b961ef37 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5547,6 +5547,29 @@ struct cgroup *cgroup_get_root(struct vfsmount *mnt)
 }
 EXPORT_SYMBOL(cgroup_get_root);
 
+struct cgroup *cgroup_kernel_lookup(struct vfsmount *mnt,
+				    const char *pathname)
+{
+	int err;
+	struct path path;
+	struct dentry *dentry;
+	struct cgroup *cgrp;
+
+	err = vfs_path_lookup(mnt->mnt_root, mnt, pathname,
+			      LOOKUP_DIRECTORY, &path);
+	if (err)
+		return ERR_PTR(err);
+	dentry = path.dentry;
+	if (dentry->d_inode) {
+		cgrp = __d_cgrp(dentry);
+		atomic_inc(&cgrp->count);
+	} else
+		cgrp = ERR_PTR(-ENOENT);
+	path_put(&path);
+	return cgrp;
+}
+EXPORT_SYMBOL(cgroup_kernel_lookup);
+
 struct cgroup *cgroup_kernel_open(struct cgroup *parent,
 		enum cgroup_open_flags flags, const char *name)
 {
-- 
2.1.4