Fix a reference counting bug in cgroupfs

As part of the extraction of cpusetfs to cgroupfs, a call to
cpuset_get_dentry() was lost (justified by the fact that the dentry in
question was now being passed down by the caller).  Since
cpuset_get_dentry() called lookup_one_len(), this resulted in a reference
count being missed from the directory dentry.

This patch removes cgroup_get_dentry() and replaces it with direct calls
to lookup_one_len(); the initialization of cgroupfs dentry ops is done
now in cgroup_create_file() at dentry creation time.

Signed-off-by: Paul Menage <[EMAIL PROTECTED]>

---
 kernel/cgroup.c |   24 +++++++-----------------
 1 file changed, 7 insertions(+), 17 deletions(-)

Index: linux-2.6.23-rc4-mm1-new/kernel/cgroup.c
===================================================================
--- linux-2.6.23-rc4-mm1-new.orig/kernel/cgroup.c
+++ linux-2.6.23-rc4-mm1-new/kernel/cgroup.c
@@ -604,19 +604,6 @@ static void cgroup_diput(struct dentry *
        iput(inode);
 }
 
-static struct dentry *cgroup_get_dentry(struct dentry *parent,
-                                          const char *name)
-{
-       struct dentry *d = lookup_one_len(name, parent, strlen(name));
-       static struct dentry_operations cgroup_dops = {
-               .d_iput = cgroup_diput,
-       };
-
-       if (!IS_ERR(d))
-               d->d_op = &cgroup_dops;
-       return d;
-}
-
 static void remove_dir(struct dentry *d)
 {
        struct dentry *parent = dget(d->d_parent);
@@ -1507,6 +1494,10 @@ static struct inode_operations cgroup_di
 static int cgroup_create_file(struct dentry *dentry, int mode,
                                struct super_block *sb)
 {
+       static struct dentry_operations cgroup_dops = {
+               .d_iput = cgroup_diput,
+       };
+
        struct inode *inode;
 
        if (!dentry)
@@ -1532,7 +1523,7 @@ static int cgroup_create_file(struct den
                inode->i_size = 0;
                inode->i_fop = &cgroup_file_operations;
        }
-
+       dentry->d_op = &cgroup_dops;
        d_instantiate(dentry, inode);
        dget(dentry);   /* Extra count - pin the dentry in core */
        return 0;
@@ -1553,13 +1544,12 @@ static int cgroup_create_dir(struct cgro
        int error = 0;
 
        parent = cont->parent->dentry;
-       if (IS_ERR(dentry))
-               return PTR_ERR(dentry);
        error = cgroup_create_file(dentry, S_IFDIR | mode, cont->root->sb);
        if (!error) {
                dentry->d_fsdata = cont;
                inc_nlink(parent->d_inode);
                cont->dentry = dentry;
+               dget(dentry);
        }
        dput(dentry);
 
@@ -1581,7 +1571,7 @@ int cgroup_add_file(struct cgroup *cont,
        }
        strcat(name, cft->name);
        BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex));
-       dentry = cgroup_get_dentry(dir, name);
+       dentry = lookup_one_len(name, dir, strlen(name));
        if (!IS_ERR(dentry)) {
                error = cgroup_create_file(dentry, 0644 | S_IFREG,
                                                cont->root->sb);

--
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