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Subject: Re: [PATCH V3 2/2] ocfs2: add locking filter debugfs file
To:     Gang He <ghe@suse.com>, mark@fasheh.com, jlbec@evilplan.org
Cc:     linux-kernel@vger.kernel.org, ocfs2-devel@oss.oracle.com,
        akpm@linux-foundation.org
References: <20190505101316.17601-1-ghe@suse.com>
From:   Joseph Qi <jiangqi903@gmail.com>
Message-ID: <70129725-0a7e-64a5-9583-81e268e26c21@gmail.com>
Date:   Sun, 5 May 2019 19:00:05 +0800
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On 19/5/5 18:13, 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@suse.com>

Reviewed-by: Joseph Qi <joseph.qi@linux.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;
>  };
>  
>