cgroup_fs: fix cgroup use of simple_lookup()

cgroup can't use simple_lookup(), since that'd override its desired ->d_op.

Tested-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 16 insertions, 1 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 5c5f4cc2e99a..ffb7bbad0638 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -764,6 +764,7 @@ EXPORT_SYMBOL_GPL(cgroup_unlock);
  */
 
 static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, int mode);
+static struct dentry *cgroup_lookup(struct inode *, struct dentry *, struct nameidata *);
 static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry);
 static int cgroup_populate_dir(struct cgroup *cgrp);
 static const struct inode_operations cgroup_dir_inode_operations;
@@ -860,6 +861,11 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode)
         iput(inode);
 }
 
+static int cgroup_delete(const struct dentry *d)
+{
+        return 1;
+}
+
 static void remove_dir(struct dentry *d)
 {
         struct dentry *parent = dget(d->d_parent);
@@ -1451,6 +1457,7 @@ static int cgroup_get_rootdir(struct super_block *sb)
 {
         static const struct dentry_operations cgroup_dops = {
                 .d_iput = cgroup_diput,
+                .d_delete = cgroup_delete,
         };
 
         struct inode *inode =
@@ -2195,12 +2202,20 @@ static const struct file_operations cgroup_file_operations = {
 };
 
 static const struct inode_operations cgroup_dir_inode_operations = {
-        .lookup = simple_lookup,
+        .lookup = cgroup_lookup,
         .mkdir = cgroup_mkdir,
         .rmdir = cgroup_rmdir,
         .rename = cgroup_rename,
 };
 
+static struct dentry *cgroup_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
+{
+        if (dentry->d_name.len > NAME_MAX)
+                return ERR_PTR(-ENAMETOOLONG);
+        d_add(dentry, NULL);
+        return NULL;
+}
+
 /*
  * Check if a file is a control file
  */