linux-kernel - Re: [Ocfs2-devel] [PATCH V3 2/2] ocfs2: add locking filter debugfs file

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Date:   Thu, 23 May 2019 20:15:07 -0600
From:   "Gang He" <ghe@...e.com>
To:     "Wengang" <wen.gang.wang@...cle.com>
Cc:     <jlbec@...lplan.org>, <mark@...heh.com>, <jiangqi903@...il.com>,
        <ocfs2-devel@....oracle.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [Ocfs2-devel] [PATCH V3 2/2] ocfs2: add locking filter
 debugfs file

Hello Wengang,

This patch is used to add a filter attribute(the default value is 0), the kernel module can use this attribute value to filter the lock resources dumping.
By default(the value is 0), the kernel module does not filter any lock resources dumping, the behavior is like before.
If the user set a value(N) of this attribute, the kernel module will only dump the latest N seconds active lock resources, this will avoid dumping lots of inactive lock resources.

Thanks
Gang

>>> On 2019/5/24 at 0:43, in message
<da93442d-3333-5bd6-ce0a-edb66a58109d@...cle.com>, Wengang
<wen.gang.wang@...cle.com> wrote:
> Hi Gang,
> 
> Could you paste an example of outputs before patch VS that after patch?
> I think that would directly show what the patch does.
> 
> thanks,
> wengang
> 
> On 05/23/2019 03:40 AM, Gang He wrote:
>> Add locking filter debugfs file, which is used to filter lock
>> resources dump from locking_state debugfs file.
>> We use d_filter_secs field to filter lock resources dump,
>> the default d_filter_secs(0) value filters nothing,
>> otherwise, only dump the last N seconds active lock resources.
>> This enhancement can avoid dumping lots of old records.
>> The d_filter_secs value can be changed via locking_filter file.
>>
>> Compared with v2, ocfs2_dlm_init_debug() returns directly with
>> error when creating locking filter debugfs file is failed, since
>> ocfs2_dlm_shutdown_debug() will handle this failure perfectly.
>> Compared with v1, the main change is to add CONFIG_OCFS2_FS_STATS
>> macro definition judgment.
>>
>> Signed-off-by: Gang He <ghe@...e.com>
>> Reviewed-by: Joseph Qi <joseph.qi@...ux.alibaba.com>
>> ---
>>   fs/ocfs2/dlmglue.c | 36 ++++++++++++++++++++++++++++++++++++
>>   fs/ocfs2/ocfs2.h   |  2 ++
>>   2 files changed, 38 insertions(+)
>>
>> diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
>> index dccf4136f8c1..fbe4562cf4fe 100644
>> --- a/fs/ocfs2/dlmglue.c
>> +++ b/fs/ocfs2/dlmglue.c
>> @@ -3006,6 +3006,8 @@ struct ocfs2_dlm_debug *ocfs2_new_dlm_debug(void)
>>   	kref_init(&dlm_debug->d_refcnt);
>>   	INIT_LIST_HEAD(&dlm_debug->d_lockres_tracking);
>>   	dlm_debug->d_locking_state = NULL;
>> +	dlm_debug->d_locking_filter = NULL;
>> +	dlm_debug->d_filter_secs = 0;
>>   out:
>>   	return dlm_debug;
>>   }
>> @@ -3104,11 +3106,33 @@ static int ocfs2_dlm_seq_show(struct seq_file *m, 
> void *v)
>>   {
>>   	int i;
>>   	char *lvb;
>> +	u32 now, last = 0;
>>   	struct ocfs2_lock_res *lockres = v;
>> +	struct ocfs2_dlm_debug *dlm_debug =
>> +			((struct ocfs2_dlm_seq_priv *)m->private)->p_dlm_debug;
>>   
>>   	if (!lockres)
>>   		return -EINVAL;
>>   
>> +	if (dlm_debug->d_filter_secs) {
>> +		now = ktime_to_timespec(ktime_get()).tv_sec;
>> +#ifdef CONFIG_OCFS2_FS_STATS
>> +		if (lockres->l_lock_prmode.ls_last >
>> +		    lockres->l_lock_exmode.ls_last)
>> +			last = lockres->l_lock_prmode.ls_last;
>> +		else
>> +			last = lockres->l_lock_exmode.ls_last;
>> +#endif
>> +		/*
>> +		 * Use d_filter_secs field to filter lock resources dump,
>> +		 * the default d_filter_secs(0) value filters nothing,
>> +		 * otherwise, only dump the last N seconds active lock
>> +		 * resources.
>> +		 */
>> +		if ((now - last) > dlm_debug->d_filter_secs)
>> +			return 0;
>> +	}
>> +
>>   	seq_printf(m, "0x%x\t", OCFS2_DLM_DEBUG_STR_VERSION);
>>   
>>   	if (lockres->l_type == OCFS2_LOCK_TYPE_DENTRY)
>> @@ -3258,6 +3282,17 @@ static int ocfs2_dlm_init_debug(struct ocfs2_super 
> *osb)
>>   		goto out;
>>   	}
>>   
>> +	dlm_debug->d_locking_filter = debugfs_create_u32("locking_filter",
>> +						0600,
>> +						osb->osb_debug_root,
>> +						&dlm_debug->d_filter_secs);
>> +	if (!dlm_debug->d_locking_filter) {
>> +		ret = -EINVAL;
>> +		mlog(ML_ERROR,
>> +		     "Unable to create locking filter debugfs file.\n");
>> +		goto out;
>> +	}
>> +
>>   	ocfs2_get_dlm_debug(dlm_debug);
>>   out:
>>   	return ret;
>> @@ -3269,6 +3304,7 @@ static void ocfs2_dlm_shutdown_debug(struct 
> ocfs2_super *osb)
>>   
>>   	if (dlm_debug) {
>>   		debugfs_remove(dlm_debug->d_locking_state);
>> +		debugfs_remove(dlm_debug->d_locking_filter);
>>   		ocfs2_put_dlm_debug(dlm_debug);
>>   	}
>>   }
>> diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
>> index 8efa022684f4..f4da51099889 100644
>> --- a/fs/ocfs2/ocfs2.h
>> +++ b/fs/ocfs2/ocfs2.h
>> @@ -237,6 +237,8 @@ struct ocfs2_orphan_scan {
>>   struct ocfs2_dlm_debug {
>>   	struct kref d_refcnt;
>>   	struct dentry *d_locking_state;
>> +	struct dentry *d_locking_filter;
>> +	u32 d_filter_secs;
>>   	struct list_head d_lockres_tracking;
>>   };
>>