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

[Junxiao Bi]

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.

> 
>> 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)
>>>
>>
>>
>> .
>>
>