[Ocfs2-devel] [PATCH] ocfs2: check if the ocfs2 lock resource be initialized before calling ocfs2_dlm_lock

[alex chen]

On 2015/4/22 9:46, Junxiao Bi wrote:
> On 04/21/2015 10:54 AM, alex chen wrote:
>> Hi Junxiao,
>>
>> On 2015/4/16 15:28, Junxiao Bi wrote:
>>> Hi Alex,
>>>
>>> On 03/30/2015 11:22 AM, alex chen wrote:
>>>> If ocfs2 lockres has not been initialized before calling ocfs2_dlm_lock,
>>>> the lock won't be dropped and then will lead umount hung. The case is
>>>> described below:
>>>>
>>>> ocfs2_mknod
>>>>     ocfs2_mknod_locked
>>>>         __ocfs2_mknod_locked
>>>>             ocfs2_journal_access_di
>>>>             Failed because of -ENOMEM or other reasons, the inode lockres
>>>>             has not been initialized yet.
>>>
>>> If failed here, is OCFS2_I(inode)->ip_inode_lockres initialized?  If not
>>
>> The OCFS2_I(inode)->ip_inode_lockres is initialized as follows:
>> __ocfs2_mknod_locked
>>     ocfs2_populate_inode
>>         ocfs2_inode_lock_res_init
>>             ocfs2_lock_res_init_common
>> So if ocfs2_journal_access_di is failed, the ip_inode_lockres will not be
>> initialized.
>> In this situation, we should not allocate a new dlm lockres through calling
>> ocfs2_dlm_lock() in __ocfs2_cluster_lock(), otherwise it will lead umount
>> hung. So we need bread __ocfs2_cluster_lock() if the inode lockres is not
>> be initialized, that is the condition
>> (!(lockres->l_flags & OCFS2_LOCK_INITIALIZED)) is TRUE.
> 
> Looks good. Just didn't remind that inode_info is init once when it is
> allocated from "ocfs2_inode_cache". lockres->l_flags is init there.
> 
> Thanks,
> Junxiao.
> 

Thank you for your remind. If the subject is "check if lockres->l_flags be
initialized to OCFS2_LOCK_INITIALIZED before calling ocfs2_dlm_lock" will
be better.

>>
>>> how can you break __ocfs2_cluster_lock with the following condition?
>>>
>>> if (!(lockres->l_flags & OCFS2_LOCK_INITIALIZED))
>>>
>>> Thanks,
>>> Junxiao.
>>>
>>>>
>>>>     iput(inode)
>>>>         ocfs2_evict_inode
>>>>             ocfs2_delete_inode
>>>>                 ocfs2_inode_lock
>>>>                     ocfs2_inode_lock_full_nested
>>>>                         __ocfs2_cluster_lock
>>>>                         Succeeds and allocates a new dlm lockres.
>>>>             ocfs2_clear_inode
>>>>                 ocfs2_open_unlock
>>>>                     ocfs2_drop_inode_locks
>>>>                         ocfs2_drop_lock
>>>>                         Since lockres has not been initialized, the lock
>>>>                         can't be dropped and the lockres can't be
>>>>                         migrated, thus umount will hang forever.
>>>>
>>>> Signed-off-by: Alex Chen <alex.chen at huawei.com>
>>>> Reviewed-by: Joseph Qi <joseph.qi at huawei.com>
>>>> Reviewed-by: joyce.xue <xuejiufei at huawei.com>
>>>>
>>>> ---
>>>>  fs/ocfs2/dlmglue.c | 5 +++++
>>>>  1 file changed, 5 insertions(+)
>>>>
>>>> diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
>>>> index 11849a4..8b23aa2 100644
>>>> --- a/fs/ocfs2/dlmglue.c
>>>> +++ b/fs/ocfs2/dlmglue.c
>>>> @@ -1391,6 +1391,11 @@ static int __ocfs2_cluster_lock(struct ocfs2_super *osb,
>>>>  	int noqueue_attempted = 0;
>>>>  	int dlm_locked = 0;
>>>>
>>>> +	if (!(lockres->l_flags & OCFS2_LOCK_INITIALIZED)) {
>>>> +		mlog_errno(-EINVAL);
>>>> +		return -EINVAL;
>>>> +	}
>>>> +
>>>>  	ocfs2_init_mask_waiter(&mw);
>>>>
>>>>  	if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB)
>>>>
>>>
>>>
>>> .
>>>
>>
> 
> 
> .
>