[v2,1/3] ocfs2: add ocfs2_try_rw_lock and ocfs2_try_inode_lock
diff mbox

Message ID 1511944612-9629-2-git-send-email-ghe@suse.com
State New
Headers show

Commit Message

Gang He Nov. 29, 2017, 8:36 a.m. UTC
Add ocfs2_try_rw_lock and ocfs2_try_inode_lock functions, which
will be used in non-block IO scenarios.

Signed-off-by: Gang He <ghe@suse.com>
---
 fs/ocfs2/dlmglue.c | 21 +++++++++++++++++++++
 fs/ocfs2/dlmglue.h |  4 ++++
 2 files changed, 25 insertions(+)

Comments

piaojun Nov. 29, 2017, 9:05 a.m. UTC | #1
On 2017/11/29 16:36, Gang He wrote:
> Add ocfs2_try_rw_lock and ocfs2_try_inode_lock functions, which
> will be used in non-block IO scenarios.
> 
> Signed-off-by: Gang He <ghe@suse.com>
Reviewed-by: Jun Piao <piaojun@huawei.com>
> ---
>  fs/ocfs2/dlmglue.c | 21 +++++++++++++++++++++
>  fs/ocfs2/dlmglue.h |  4 ++++
>  2 files changed, 25 insertions(+)
> 
> diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
> index 4689940..a68efa3 100644
> --- a/fs/ocfs2/dlmglue.c
> +++ b/fs/ocfs2/dlmglue.c
> @@ -1742,6 +1742,27 @@ int ocfs2_rw_lock(struct inode *inode, int write)
>  	return status;
>  }
>  
> +int ocfs2_try_rw_lock(struct inode *inode, int write)
> +{
> +	int status, level;
> +	struct ocfs2_lock_res *lockres;
> +	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
> +
> +	mlog(0, "inode %llu try to take %s RW lock\n",
> +	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
> +	     write ? "EXMODE" : "PRMODE");
> +
> +	if (ocfs2_mount_local(osb))
> +		return 0;
> +
> +	lockres = &OCFS2_I(inode)->ip_rw_lockres;
> +
> +	level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
> +
> +	status = ocfs2_cluster_lock(osb, lockres, level, DLM_LKF_NOQUEUE, 0);
> +	return status;
> +}
> +
>  void ocfs2_rw_unlock(struct inode *inode, int write)
>  {
>  	int level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
> diff --git a/fs/ocfs2/dlmglue.h b/fs/ocfs2/dlmglue.h
> index a7fc18b..05910fc 100644
> --- a/fs/ocfs2/dlmglue.h
> +++ b/fs/ocfs2/dlmglue.h
> @@ -116,6 +116,7 @@ void ocfs2_refcount_lock_res_init(struct ocfs2_lock_res *lockres,
>  int ocfs2_create_new_inode_locks(struct inode *inode);
>  int ocfs2_drop_inode_locks(struct inode *inode);
>  int ocfs2_rw_lock(struct inode *inode, int write);
> +int ocfs2_try_rw_lock(struct inode *inode, int write);
>  void ocfs2_rw_unlock(struct inode *inode, int write);
>  int ocfs2_open_lock(struct inode *inode);
>  int ocfs2_try_open_lock(struct inode *inode, int write);
> @@ -140,6 +141,9 @@ int ocfs2_inode_lock_with_page(struct inode *inode,
>  /* 99% of the time we don't want to supply any additional flags --
>   * those are for very specific cases only. */
>  #define ocfs2_inode_lock(i, b, e) ocfs2_inode_lock_full_nested(i, b, e, 0, OI_LS_NORMAL)
> +#define ocfs2_try_inode_lock(i, b, e)\
> +		ocfs2_inode_lock_full_nested(i, b, e, OCFS2_META_LOCK_NOQUEUE,\
> +		OI_LS_NORMAL)
>  void ocfs2_inode_unlock(struct inode *inode,
>  		       int ex);
>  int ocfs2_super_lock(struct ocfs2_super *osb,
>
Changwei Ge Nov. 29, 2017, 12:02 p.m. UTC | #2
On 2017/11/29 16:38, Gang He wrote:
> Add ocfs2_try_rw_lock and ocfs2_try_inode_lock functions, which
> will be used in non-block IO scenarios.
> 
> Signed-off-by: Gang He <ghe@suse.com>
> ---
>   fs/ocfs2/dlmglue.c | 21 +++++++++++++++++++++
>   fs/ocfs2/dlmglue.h |  4 ++++
>   2 files changed, 25 insertions(+)
> 
> diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
> index 4689940..a68efa3 100644
> --- a/fs/ocfs2/dlmglue.c
> +++ b/fs/ocfs2/dlmglue.c
> @@ -1742,6 +1742,27 @@ int ocfs2_rw_lock(struct inode *inode, int write)
>   	return status;
>   }
>   
> +int ocfs2_try_rw_lock(struct inode *inode, int write)
> +{
> +	int status, level;
> +	struct ocfs2_lock_res *lockres;
> +	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
> +
> +	mlog(0, "inode %llu try to take %s RW lock\n",
> +	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
> +	     write ? "EXMODE" : "PRMODE");
> +
> +	if (ocfs2_mount_local(osb))
> +		return 0;
> +
> +	lockres = &OCFS2_I(inode)->ip_rw_lockres;
> +
> +	level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
> +
> +	status = ocfs2_cluster_lock(osb, lockres, level, DLM_LKF_NOQUEUE, 0);

Hi Gang,
Should we consider about passing a flag - OCFS2_LOCK_NONBLOCK to 
ocfs2_cluster_lock. Otherwise a cluster locking progress may be waiting 
for accomplishment of DC, which I think violates _NO_WAIT_ semantics.

Thanks,
Changwei.

> +	return status;
> +}
> +
>   void ocfs2_rw_unlock(struct inode *inode, int write)
>   {
>   	int level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
> diff --git a/fs/ocfs2/dlmglue.h b/fs/ocfs2/dlmglue.h
> index a7fc18b..05910fc 100644
> --- a/fs/ocfs2/dlmglue.h
> +++ b/fs/ocfs2/dlmglue.h
> @@ -116,6 +116,7 @@ void ocfs2_refcount_lock_res_init(struct ocfs2_lock_res *lockres,
>   int ocfs2_create_new_inode_locks(struct inode *inode);
>   int ocfs2_drop_inode_locks(struct inode *inode);
>   int ocfs2_rw_lock(struct inode *inode, int write);
> +int ocfs2_try_rw_lock(struct inode *inode, int write);
>   void ocfs2_rw_unlock(struct inode *inode, int write);
>   int ocfs2_open_lock(struct inode *inode);
>   int ocfs2_try_open_lock(struct inode *inode, int write);
> @@ -140,6 +141,9 @@ int ocfs2_inode_lock_with_page(struct inode *inode,
>   /* 99% of the time we don't want to supply any additional flags --
>    * those are for very specific cases only. */
>   #define ocfs2_inode_lock(i, b, e) ocfs2_inode_lock_full_nested(i, b, e, 0, OI_LS_NORMAL)
> +#define ocfs2_try_inode_lock(i, b, e)\
> +		ocfs2_inode_lock_full_nested(i, b, e, OCFS2_META_LOCK_NOQUEUE,\
> +		OI_LS_NORMAL)
>   void ocfs2_inode_unlock(struct inode *inode,
>   		       int ex);
>   int ocfs2_super_lock(struct ocfs2_super *osb,
>
Gang He Nov. 30, 2017, 2:44 a.m. UTC | #3
Hello Changwei,


>>> 
> On 2017/11/29 16:38, Gang He wrote:
>> Add ocfs2_try_rw_lock and ocfs2_try_inode_lock functions, which
>> will be used in non-block IO scenarios.
>> 
>> Signed-off-by: Gang He <ghe@suse.com>
>> ---
>>   fs/ocfs2/dlmglue.c | 21 +++++++++++++++++++++
>>   fs/ocfs2/dlmglue.h |  4 ++++
>>   2 files changed, 25 insertions(+)
>> 
>> diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
>> index 4689940..a68efa3 100644
>> --- a/fs/ocfs2/dlmglue.c
>> +++ b/fs/ocfs2/dlmglue.c
>> @@ -1742,6 +1742,27 @@ int ocfs2_rw_lock(struct inode *inode, int write)
>>   	return status;
>>   }
>>   
>> +int ocfs2_try_rw_lock(struct inode *inode, int write)
>> +{
>> +	int status, level;
>> +	struct ocfs2_lock_res *lockres;
>> +	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>> +
>> +	mlog(0, "inode %llu try to take %s RW lock\n",
>> +	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
>> +	     write ? "EXMODE" : "PRMODE");
>> +
>> +	if (ocfs2_mount_local(osb))
>> +		return 0;
>> +
>> +	lockres = &OCFS2_I(inode)->ip_rw_lockres;
>> +
>> +	level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
>> +
>> +	status = ocfs2_cluster_lock(osb, lockres, level, DLM_LKF_NOQUEUE, 0);
> 
> Hi Gang,
> Should we consider about passing a flag - OCFS2_LOCK_NONBLOCK to 
> ocfs2_cluster_lock. Otherwise a cluster locking progress may be waiting 
> for accomplishment of DC, which I think violates _NO_WAIT_ semantics.

If ocfs2 is a local file system, we should not wait for any condition, but for a cluster file system,
we cannot avoid this totally according to the current DLM lock design, we need to wait for a little to get lock for the first time.
Why do we not use OCFS2_LOCK_NONBLOCK flag to get a lock?
since this flag is not stable to get a lock no matter this lock is occupied by other nodes, or not.
If you use OCFS2_LOCK_NONBLOCK flag to get a fresh lock, you possibly fail or success, depends on when the lock acquisition callback happens.
So, I think DLM_LKF_NOQUEUE flag should be more matched to _NO_WAIT_ semantics.
we always get a fresh lock successfully, always failed if the lock is/was occupied by other nodes.
This flag can give us a consistent locking behavior.

Thanks
Gang



> 
> Thanks,
> Changwei.
> 
>> +	return status;
>> +}
>> +
>>   void ocfs2_rw_unlock(struct inode *inode, int write)
>>   {
>>   	int level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
>> diff --git a/fs/ocfs2/dlmglue.h b/fs/ocfs2/dlmglue.h
>> index a7fc18b..05910fc 100644
>> --- a/fs/ocfs2/dlmglue.h
>> +++ b/fs/ocfs2/dlmglue.h
>> @@ -116,6 +116,7 @@ void ocfs2_refcount_lock_res_init(struct ocfs2_lock_res 
> *lockres,
>>   int ocfs2_create_new_inode_locks(struct inode *inode);
>>   int ocfs2_drop_inode_locks(struct inode *inode);
>>   int ocfs2_rw_lock(struct inode *inode, int write);
>> +int ocfs2_try_rw_lock(struct inode *inode, int write);
>>   void ocfs2_rw_unlock(struct inode *inode, int write);
>>   int ocfs2_open_lock(struct inode *inode);
>>   int ocfs2_try_open_lock(struct inode *inode, int write);
>> @@ -140,6 +141,9 @@ int ocfs2_inode_lock_with_page(struct inode *inode,
>>   /* 99% of the time we don't want to supply any additional flags --
>>    * those are for very specific cases only. */
>>   #define ocfs2_inode_lock(i, b, e) ocfs2_inode_lock_full_nested(i, b, e, 0, 
> OI_LS_NORMAL)
>> +#define ocfs2_try_inode_lock(i, b, e)\
>> +		ocfs2_inode_lock_full_nested(i, b, e, OCFS2_META_LOCK_NOQUEUE,\
>> +		OI_LS_NORMAL)
>>   void ocfs2_inode_unlock(struct inode *inode,
>>   		       int ex);
>>   int ocfs2_super_lock(struct ocfs2_super *osb,
>>
Changwei Ge Nov. 30, 2017, 3:01 a.m. UTC | #4
Hi Gang,

On 2017/11/30 10:45, Gang He wrote:
> Hello Changwei,
> 
> 
>>>>
>> On 2017/11/29 16:38, Gang He wrote:
>>> Add ocfs2_try_rw_lock and ocfs2_try_inode_lock functions, which
>>> will be used in non-block IO scenarios.
>>>
>>> Signed-off-by: Gang He <ghe@suse.com>
>>> ---
>>>    fs/ocfs2/dlmglue.c | 21 +++++++++++++++++++++
>>>    fs/ocfs2/dlmglue.h |  4 ++++
>>>    2 files changed, 25 insertions(+)
>>>
>>> diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
>>> index 4689940..a68efa3 100644
>>> --- a/fs/ocfs2/dlmglue.c
>>> +++ b/fs/ocfs2/dlmglue.c
>>> @@ -1742,6 +1742,27 @@ int ocfs2_rw_lock(struct inode *inode, int write)
>>>    	return status;
>>>    }
>>>    
>>> +int ocfs2_try_rw_lock(struct inode *inode, int write)
>>> +{
>>> +	int status, level;
>>> +	struct ocfs2_lock_res *lockres;
>>> +	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>>> +
>>> +	mlog(0, "inode %llu try to take %s RW lock\n",
>>> +	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
>>> +	     write ? "EXMODE" : "PRMODE");
>>> +
>>> +	if (ocfs2_mount_local(osb))
>>> +		return 0;
>>> +
>>> +	lockres = &OCFS2_I(inode)->ip_rw_lockres;
>>> +
>>> +	level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
>>> +
>>> +	status = ocfs2_cluster_lock(osb, lockres, level, DLM_LKF_NOQUEUE, 0);
>>
>> Hi Gang,
>> Should we consider about passing a flag - OCFS2_LOCK_NONBLOCK to
>> ocfs2_cluster_lock. Otherwise a cluster locking progress may be waiting
>> for accomplishment of DC, which I think violates _NO_WAIT_ semantics.
> 
> If ocfs2 is a local file system, we should not wait for any condition, but for a cluster file system,
> we cannot avoid this totally according to the current DLM lock design, we need to wait for a little to get lock for the first time.
> Why do we not use OCFS2_LOCK_NONBLOCK flag to get a lock?
> since this flag is not stable to get a lock no matter this lock is occupied by other nodes, or not.
I suppose local node must be granted under the condition that it is 
marked with *OCFS2_LOCK_BLOCKED*. And the control flag 
_OCFS2_LOCK_NONBLOCK_ will make lock progress directly return -EAGAIN 
without any waiting.

> If you use OCFS2_LOCK_NONBLOCK flag to get a fresh lock, you possibly fail or success, depends on when the lock acquisition callback happens.
> So, I think DLM_LKF_NOQUEUE flag should be more matched to _NO_WAIT_ semantics.

I thinks OCFS2_LOCK_NONBLOCK doesn't conflict DLM_LKF_NOQUEUE, they are 
the forth and fifth argument respectively.

> we always get a fresh lock successfully, always failed if the lock is/was occupied by other nodes.

What do you mean by a fresh lock? A lock that is never granted or 
acquired? If a lock is marked with OCFS2_LOCK_BLOCKED, local node must 
has acquired it.

Thanks,
Changwei

> This flag can give us a consistent locking behavior.
> 
> Thanks
> Gang
> 
> 
> 
>>
>> Thanks,
>> Changwei.
>>
>>> +	return status;
>>> +}
>>> +
>>>    void ocfs2_rw_unlock(struct inode *inode, int write)
>>>    {
>>>    	int level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
>>> diff --git a/fs/ocfs2/dlmglue.h b/fs/ocfs2/dlmglue.h
>>> index a7fc18b..05910fc 100644
>>> --- a/fs/ocfs2/dlmglue.h
>>> +++ b/fs/ocfs2/dlmglue.h
>>> @@ -116,6 +116,7 @@ void ocfs2_refcount_lock_res_init(struct ocfs2_lock_res
>> *lockres,
>>>    int ocfs2_create_new_inode_locks(struct inode *inode);
>>>    int ocfs2_drop_inode_locks(struct inode *inode);
>>>    int ocfs2_rw_lock(struct inode *inode, int write);
>>> +int ocfs2_try_rw_lock(struct inode *inode, int write);
>>>    void ocfs2_rw_unlock(struct inode *inode, int write);
>>>    int ocfs2_open_lock(struct inode *inode);
>>>    int ocfs2_try_open_lock(struct inode *inode, int write);
>>> @@ -140,6 +141,9 @@ int ocfs2_inode_lock_with_page(struct inode *inode,
>>>    /* 99% of the time we don't want to supply any additional flags --
>>>     * those are for very specific cases only. */
>>>    #define ocfs2_inode_lock(i, b, e) ocfs2_inode_lock_full_nested(i, b, e, 0,
>> OI_LS_NORMAL)
>>> +#define ocfs2_try_inode_lock(i, b, e)\
>>> +		ocfs2_inode_lock_full_nested(i, b, e, OCFS2_META_LOCK_NOQUEUE,\
>>> +		OI_LS_NORMAL)
>>>    void ocfs2_inode_unlock(struct inode *inode,
>>>    		       int ex);
>>>    int ocfs2_super_lock(struct ocfs2_super *osb,
>>>
> 
>
Gang He Nov. 30, 2017, 3:21 a.m. UTC | #5
Hi Changwei,


>>> 
> Hi Gang,
> 
> On 2017/11/30 10:45, Gang He wrote:
>> Hello Changwei,
>> 
>> 
>>>>>
>>> On 2017/11/29 16:38, Gang He wrote:
>>>> Add ocfs2_try_rw_lock and ocfs2_try_inode_lock functions, which
>>>> will be used in non-block IO scenarios.
>>>>
>>>> Signed-off-by: Gang He <ghe@suse.com>
>>>> ---
>>>>    fs/ocfs2/dlmglue.c | 21 +++++++++++++++++++++
>>>>    fs/ocfs2/dlmglue.h |  4 ++++
>>>>    2 files changed, 25 insertions(+)
>>>>
>>>> diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
>>>> index 4689940..a68efa3 100644
>>>> --- a/fs/ocfs2/dlmglue.c
>>>> +++ b/fs/ocfs2/dlmglue.c
>>>> @@ -1742,6 +1742,27 @@ int ocfs2_rw_lock(struct inode *inode, int write)
>>>>    	return status;
>>>>    }
>>>>    
>>>> +int ocfs2_try_rw_lock(struct inode *inode, int write)
>>>> +{
>>>> +	int status, level;
>>>> +	struct ocfs2_lock_res *lockres;
>>>> +	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>>>> +
>>>> +	mlog(0, "inode %llu try to take %s RW lock\n",
>>>> +	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
>>>> +	     write ? "EXMODE" : "PRMODE");
>>>> +
>>>> +	if (ocfs2_mount_local(osb))
>>>> +		return 0;
>>>> +
>>>> +	lockres = &OCFS2_I(inode)->ip_rw_lockres;
>>>> +
>>>> +	level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
>>>> +
>>>> +	status = ocfs2_cluster_lock(osb, lockres, level, DLM_LKF_NOQUEUE, 0);
>>>
>>> Hi Gang,
>>> Should we consider about passing a flag - OCFS2_LOCK_NONBLOCK to
>>> ocfs2_cluster_lock. Otherwise a cluster locking progress may be waiting
>>> for accomplishment of DC, which I think violates _NO_WAIT_ semantics.
>> 
>> If ocfs2 is a local file system, we should not wait for any condition, but 
> for a cluster file system,
>> we cannot avoid this totally according to the current DLM lock design, we 
> need to wait for a little to get lock for the first time.
>> Why do we not use OCFS2_LOCK_NONBLOCK flag to get a lock?
>> since this flag is not stable to get a lock no matter this lock is occupied 
> by other nodes, or not.
> I suppose local node must be granted under the condition that it is 
> marked with *OCFS2_LOCK_BLOCKED*. And the control flag 
> _OCFS2_LOCK_NONBLOCK_ will make lock progress directly return -EAGAIN 
> without any waiting.
> 
>> If you use OCFS2_LOCK_NONBLOCK flag to get a fresh lock, you possibly fail 
> or success, depends on when the lock acquisition callback happens.
>> So, I think DLM_LKF_NOQUEUE flag should be more matched to _NO_WAIT_ 
> semantics.
> 
> I thinks OCFS2_LOCK_NONBLOCK doesn't conflict DLM_LKF_NOQUEUE, they are 
> the forth and fifth argument respectively.
Two arguments doesn't conflict, 
but the _OCFS2_LOCK_NONBLOCK_ flag will bring the uncertainty of lock acquisition, since depends on when the lock acquisition callback happens.
In the other words, you possibly do not get a lock for one time if passing the _OCFS2_LOCK_NONBLOCK_ flag.
I think that this flag is suitable to ocfs2_inode_lock_with_page case, since when we can not get the lock immediately, we can try it again and again.
In actually, introducing this flag is to avoid a dead-lock case, a very tricky case. 

Thanks
Gang 


> 
>> we always get a fresh lock successfully, always failed if the lock is/was 
> occupied by other nodes.
> 
> What do you mean by a fresh lock? A lock that is never granted or 
> acquired? If a lock is marked with OCFS2_LOCK_BLOCKED, local node must 
> has acquired it.
> 
> Thanks,
> Changwei
> 
>> This flag can give us a consistent locking behavior.
>> 
>> Thanks
>> Gang
>> 
>> 
>> 
>>>
>>> Thanks,
>>> Changwei.
>>>
>>>> +	return status;
>>>> +}
>>>> +
>>>>    void ocfs2_rw_unlock(struct inode *inode, int write)
>>>>    {
>>>>    	int level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
>>>> diff --git a/fs/ocfs2/dlmglue.h b/fs/ocfs2/dlmglue.h
>>>> index a7fc18b..05910fc 100644
>>>> --- a/fs/ocfs2/dlmglue.h
>>>> +++ b/fs/ocfs2/dlmglue.h
>>>> @@ -116,6 +116,7 @@ void ocfs2_refcount_lock_res_init(struct ocfs2_lock_res
>>> *lockres,
>>>>    int ocfs2_create_new_inode_locks(struct inode *inode);
>>>>    int ocfs2_drop_inode_locks(struct inode *inode);
>>>>    int ocfs2_rw_lock(struct inode *inode, int write);
>>>> +int ocfs2_try_rw_lock(struct inode *inode, int write);
>>>>    void ocfs2_rw_unlock(struct inode *inode, int write);
>>>>    int ocfs2_open_lock(struct inode *inode);
>>>>    int ocfs2_try_open_lock(struct inode *inode, int write);
>>>> @@ -140,6 +141,9 @@ int ocfs2_inode_lock_with_page(struct inode *inode,
>>>>    /* 99% of the time we don't want to supply any additional flags --
>>>>     * those are for very specific cases only. */
>>>>    #define ocfs2_inode_lock(i, b, e) ocfs2_inode_lock_full_nested(i, b, e, 
> 0,
>>> OI_LS_NORMAL)
>>>> +#define ocfs2_try_inode_lock(i, b, e)\
>>>> +		ocfs2_inode_lock_full_nested(i, b, e, OCFS2_META_LOCK_NOQUEUE,\
>>>> +		OI_LS_NORMAL)
>>>>    void ocfs2_inode_unlock(struct inode *inode,
>>>>    		       int ex);
>>>>    int ocfs2_super_lock(struct ocfs2_super *osb,
>>>>
>> 
>>

Patch
diff mbox

diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 4689940..a68efa3 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -1742,6 +1742,27 @@  int ocfs2_rw_lock(struct inode *inode, int write)
 	return status;
 }
 
+int ocfs2_try_rw_lock(struct inode *inode, int write)
+{
+	int status, level;
+	struct ocfs2_lock_res *lockres;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+	mlog(0, "inode %llu try to take %s RW lock\n",
+	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
+	     write ? "EXMODE" : "PRMODE");
+
+	if (ocfs2_mount_local(osb))
+		return 0;
+
+	lockres = &OCFS2_I(inode)->ip_rw_lockres;
+
+	level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
+
+	status = ocfs2_cluster_lock(osb, lockres, level, DLM_LKF_NOQUEUE, 0);
+	return status;
+}
+
 void ocfs2_rw_unlock(struct inode *inode, int write)
 {
 	int level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
diff --git a/fs/ocfs2/dlmglue.h b/fs/ocfs2/dlmglue.h
index a7fc18b..05910fc 100644
--- a/fs/ocfs2/dlmglue.h
+++ b/fs/ocfs2/dlmglue.h
@@ -116,6 +116,7 @@  void ocfs2_refcount_lock_res_init(struct ocfs2_lock_res *lockres,
 int ocfs2_create_new_inode_locks(struct inode *inode);
 int ocfs2_drop_inode_locks(struct inode *inode);
 int ocfs2_rw_lock(struct inode *inode, int write);
+int ocfs2_try_rw_lock(struct inode *inode, int write);
 void ocfs2_rw_unlock(struct inode *inode, int write);
 int ocfs2_open_lock(struct inode *inode);
 int ocfs2_try_open_lock(struct inode *inode, int write);
@@ -140,6 +141,9 @@  int ocfs2_inode_lock_with_page(struct inode *inode,
 /* 99% of the time we don't want to supply any additional flags --
  * those are for very specific cases only. */
 #define ocfs2_inode_lock(i, b, e) ocfs2_inode_lock_full_nested(i, b, e, 0, OI_LS_NORMAL)
+#define ocfs2_try_inode_lock(i, b, e)\
+		ocfs2_inode_lock_full_nested(i, b, e, OCFS2_META_LOCK_NOQUEUE,\
+		OI_LS_NORMAL)
 void ocfs2_inode_unlock(struct inode *inode,
 		       int ex);
 int ocfs2_super_lock(struct ocfs2_super *osb,