Re: [Ocfs2-devel] [PATCH 1/2] ocfs2: dlmfs: not clear USER_LOCK_ATTACHED when destroy lock

[Joseph Qi via Ocfs2-devel <ocfs2-devel@oss.oracle.com>]

On 5/18/22 12:12 AM, Junxiao Bi wrote:
> 
> On 5/16/22 6:58 PM, Joseph Qi wrote:
>>
>> On 5/17/22 12:30 AM, Junxiao Bi wrote:
>>> On 5/15/22 7:57 AM, Joseph Qi wrote:
>>>> On 5/14/22 12:27 AM, Junxiao Bi wrote:
>>>>> On 5/12/22 7:05 PM, Joseph Qi wrote:
>>>>>
>>>>>> On 5/11/22 7:22 AM, Junxiao Bi wrote:
>>>>>>> The following function is the only place that check USER_LOCK_ATTACHED,
>>>>>>> this flag is set when lock request is granted through user_bast() and
>>>>>>> only the following function will clear it.
>>>>>>>
>>>>>> user_ast?
>>>>> Good catch, that's a typo, should be user_ast.
>>>>>>> Checking of this flag here is to make sure ocfs2_dlm_unlock is not
>>>>>>> issued if this lock is never granted. For example, lock file is created
>>>>>>> and then get removed, open file never happens.
>>>>>>>
>>>>>>> Clearing the flag here is not necessary because this is the only function
>>>>>>> that checks it, if another flow is executing user_dlm_destroy_lock(), it
>>>>>>> will bail out at the beginning because of USER_LOCK_IN_TEARDOWN and never
>>>>>>> check USER_LOCK_ATTACHED.
>>>>>>> Drop the clear, so we don't need take care it for the following
>>>>>>> error handling patch.
>>>>>>>
>>>>>> Seems it depends on initializing lockres every time, but it seems this
>>>>>> is not true for directory now.
>>>>> Sorry, i didn't get this. Can you elaborate this?
>>>>>
>>>> lockres may be reused and if we don't reinitialized, the left flag can
>>>> cause unexpected behavior.
>>> I don't know how it could get reused since it's going to be removed. Anyway USER_LOCK_IN_TEARDOWN is still set in lockres. All the flow will bail out because of this flag.
>>>
>> dlmfs_inode_private is allocated from kmem_cache.
>> The case I'm thinking about is, calling user_dlm_destroy_lock() without
>> a valid ast comming before. So checking USER_LOCK_ATTACHED here may be
>> incorrect.
>> But look more closer, it seems that lockres is unused for directories.
>> So it won't be a real issue.
> Yes, lock is only for file, not direcotry.
>> Could you please send a new version with update description?
> 
> Sorry, little confused, which part of description needs update?
> 

The typo that user_ast() is for granting lock request. And better to include
the information we discussed above.

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