20:48, Hillf Danton wrote:
> On Thu, Mar 1, 2012 at 2:17 PM, Li Zefan <lizf@xxxxxxxxxxxxxx> wrote:
>>
>> -static void cgroup_clear_directory(struct dentry *dentry)
>> +static void cgroup_clear_directory(struct dentry *dentry, bool remove_all,
>> + unsigned long removed_bits)
>> {
>> - struct list_head *node;
>> + LIST_HEAD(head);
>> + struct dentry *d, *node;
>>
>> BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
>> +
>> spin_lock(&dentry->d_lock);
>> - node = dentry->d_subdirs.next;
>> - while (node != &dentry->d_subdirs) {
>> - struct dentry *d = list_entry(node, struct dentry, d_u.d_child);
>> + list_for_each_entry_safe(d, node, &dentry->d_subdirs, d_u.d_child) {
>> + struct cftype *cft = d->d_fsdata;
>> +
>> + if (!remove_all && cft->subsys &&
>> + !test_bit(cft->subsys->subsys_id, &removed_bits))
>> + continue;
>>
>> spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
>> - list_del_init(node);
>> + list_move(&d->d_u.d_child, &head);
>> if (d->d_inode) {
>> /* This should never be called on a cgroup
>> * directory with child cgroups */
>> BUG_ON(d->d_inode->i_mode & S_IFDIR);
>> dget_dlock(d);
>> - spin_unlock(&d->d_lock);
>> - spin_unlock(&dentry->d_lock);
>> + }
>> + spin_unlock(&d->d_lock);
>> + }
>> + spin_unlock(&dentry->d_lock);
>> +
>
> Safe to process isolated entries without dentry->d_lock held?
>
no vfs expert, I need to check into the vfs code.
> -hd
>
>> + list_for_each_entry_safe(d, node, &head, d_u.d_child) {
>> + spin_lock(&d->d_lock);
>> + list_del_init(&d->d_u.d_child);
>> + spin_unlock(&d->d_lock);
>> + if (d->d_inode) {
>> d_delete(d);
>> simple_unlink(dentry->d_inode, d);
>> dput(d);
>> - spin_lock(&dentry->d_lock);
>> - } else
>> - spin_unlock(&d->d_lock);
>> - node = dentry->d_subdirs.next;
>> + }
>> }
>> - spin_unlock(&dentry->d_lock);
>> }
>>
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