ocfs2: add locking filter debugfs file

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.

[akpm@linux-foundation.org: fix undefined reference to `__udivdi3']
Link: http://lkml.kernel.org/r/20190611015414.27754-2-ghe@suse.com
Signed-off-by: Gang He <ghe@suse.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>	[build-tested]
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 40 insertions, 0 deletions

diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 5f696be267e7..4089daba4c6f 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -2991,6 +2991,8 @@ 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;
 }
@@ -3090,10 +3092,34 @@ static int ocfs2_dlm_seq_show(struct seq_file *m, void *v)
         int i;
         char *lvb;
         struct ocfs2_lock_res *lockres = v;
+#ifdef CONFIG_OCFS2_FS_STATS
+        u64 now, last;
+        struct ocfs2_dlm_debug *dlm_debug =
+                        ((struct ocfs2_dlm_seq_priv *)m->private)->p_dlm_debug;
+#endif
 
         if (!lockres)
                 return -EINVAL;
 
+#ifdef CONFIG_OCFS2_FS_STATS
+        if (dlm_debug->d_filter_secs) {
+                now = ktime_to_us(ktime_get_real());
+                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;
+                /*
+                 * 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 (div_u64(now - last, 1000000) > dlm_debug->d_filter_secs)
+                        return 0;
+        }
+#endif
+
         seq_printf(m, "0x%x\t", OCFS2_DLM_DEBUG_STR_VERSION);
 
         if (lockres->l_type == OCFS2_LOCK_TYPE_DENTRY)
@@ -3243,6 +3269,17 @@ 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;
@@ -3254,6 +3291,7 @@ 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 5c111eabaa1d..c7539601555b 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -223,6 +223,8 @@ 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;
 };