[Ocfs2-devel] [PATCH 1/4] ocfs2: Fix freeing uninitialized resource on ocfs2_dlm_shutdown

[heming.zhao at suse.com]

On 8/10/22 09:31, Joseph Qi wrote:
> 
> 
> On 8/8/22 8:09 PM, Heming Zhao wrote:
>> On Mon, Aug 08, 2022 at 02:51:12PM +0800, Joseph Qi wrote:
>>>
>>>
>>> On 7/30/22 9:14 AM, Heming Zhao wrote:
>>>> On local mount mode, there is no dlm resource initalized. If
>>>> ocfs2_mount_volume() fails in ocfs2_find_slot(), error handling
>>>> flow will call ocfs2_dlm_shutdown(), then does dlm resource
>>>> cleanup job, which will trigger kernel crash.
>>>>
>>>> Fixes: 0737e01de9c4 ("ocfs2: ocfs2_mount_volume does cleanup job before
>>>> return error")
>>>
>>> Should be put at the same line.
>> OK
>>
>>>
>>>> Signed-off-by: Heming Zhao <heming.zhao at suse.com>
>>>> ---
>>>>   fs/ocfs2/dlmglue.c | 3 +++
>>>>   1 file changed, 3 insertions(+)
>>>>
>>>> diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
>>>> index 801e60bab955..1438ac14940b 100644
>>>> --- a/fs/ocfs2/dlmglue.c
>>>> +++ b/fs/ocfs2/dlmglue.c
>>>> @@ -3385,6 +3385,9 @@ int ocfs2_dlm_init(struct ocfs2_super *osb)
>>>>   void ocfs2_dlm_shutdown(struct ocfs2_super *osb,
>>>>   			int hangup_pending)
>>>>   {
>>>> +	if (ocfs2_mount_local(osb))
>>>> +		return;
>>>> +
>>>
>>> IMO, we have to do part of ocfs2_dlm_shutdown() jobs such as
>>> ocfs2_lock_res_free(), which will remove lockres from d_lockres_tracking
>>> added by ocfs2_xxx_lock_res_init().
>>>
>>
>> ocfs2_dlm_shutdown does the cleanup job for ocfs2_dlm_init.
>> This patch fixed crash in local mount error flow.
>> In local mount mode, ocfs2_dlm_init does nothing, which should make
>> ocfs2_dlm_shutdown do nothing.
>>
> Not exactly, even in local mount we have to initialize lockres like
> super lock.

Thank you for your patient explaination, I understood your meaning, will change it in
next version.
I am very busy these days, it makes my brain stop working.

> 
> 
>> And I checked all calling ocfs2_dlm_shutdown cases:
>> 1. mount flow:
>>
>>     ocfs2_fill_super
>>      + xxx =fails=> label:out_super (checked, work fine)
>>      |
>>      + ocfs2_mount_volume =fails=> label:out_debugfs (checked, work fine)
>>      |  |
>>      |  + xxx =fails=> cleanup everything before returning
>>      |
>>      + xxx =fails=> label:out_dismout
>>           At this time, dlm has been init successfully, we can call all lines
>>           of ocfs2_dlm_shutdown.
>>      
>>     
>> 2. ocfs2_dismount_volume => 'osb->cconn' is true.
>>     this MUST be dlm successfully init case. everything looks fine.
>>
>> In previous mail/patch: [PATCH] test error handling during mount stage, I may
>> forget to test local mount mode. So this crash didn't be triggered.
>>
>>> Before commit 0737e01de9c4, it seems this issue also exists since
>>> osb->cconn is already set under local mount mode.
>>
>> Yes. The bug exists since local mount feature was introduced, commit number:
>> c271c5c22b0a7ca45fda15f1f4d258bca36a5b94.  I will change 'Fixes' on next version.
>>
> This patch can be a separate fix and we don't have to bind with
> nocluster mount feature, even though you've triggered it by related
> local mount.

OK.

> 
> Thanks,
> Joseph
> 
>> (Hope 'CC' list takes effect for this mail. -_-# )
>>
>> Thanks,
>> Heming

Thanks,
Heming